neplan user guide

NEPLAN® User’s Guide

Electrical

Version 5

Busarello + Cott + Partner Inc. ABB Utilities Gmbh Bahnhofstrasse 40 Käfertalerstrasse 250 CH-8703 Erlenbach D-68167 Mannheim Switzerland Germany Phone: +41 1 914 36 66 +49 621 386 27 86 Fax: +41 1 991 19 71 +49 621 386 27 85 E-mail: [email protected] [email protected] Internet: www.neplan.ch www.abb.de/neplan

mailto:[email protected]

mailto:[email protected]

http://www.neplan.ch/

http://www.abb.de/neplan

Contents

NEPLAN User's Guide V5 0-2

Contents TUTORIAL...............................................................................................................................1

INTRODUCTION ........................................................................................................................1 THE USER INTERFACE..............................................................................................................2

Toolbar ...............................................................................................................................2 Workspace ..........................................................................................................................3 Variant Manager ................................................................................................................3 Symbol Window ..................................................................................................................3 Message Window ................................................................................................................3

THE ONLINE HELP ...................................................................................................................4 DATA ORGANIZATION .............................................................................................................5 THE BASIC ELEMENTS OF NEPLAN........................................................................................6

Nodes ..................................................................................................................................6 Elements..............................................................................................................................7 Protection Devices, Current and Voltage Transformers....................................................7 Station.................................................................................................................................7 Symbol ................................................................................................................................8 Switches ..............................................................................................................................8 Zones and Areas .................................................................................................................8 Partial Networks.................................................................................................................8

STEP 1 – CREATE A NEW PROJECT .........................................................................................10 STEP 2 – ENTER A SMALL NETWORK......................................................................................12

Input data..........................................................................................................................12 Enter the network..............................................................................................................14 Test your network .............................................................................................................20

STEP 3 – INSERT HEADER, SAVE, PRINT, EXIT ......................................................................23 Insert Header ....................................................................................................................23 Save the network ...............................................................................................................25 Print the diagram..............................................................................................................26 Close and open projects ...................................................................................................27

STEP 4 – USE OF DIAGRAMS, LAYERS, AREAS AND ZONES...................................................29 Use of Diagrams...............................................................................................................29 Use of graphic layers........................................................................................................34 Define and assign Areas and Zones .................................................................................39

STEP 5 – CREATE AND USE LIBRARIES...................................................................................47 Create a new Library........................................................................................................47 Import data from a library................................................................................................51 Update your network data with a library type .................................................................52 Export data to a library ....................................................................................................53

STEP 6 – DEFINE VARIANTS ...................................................................................................56 Insert new Subvariants .....................................................................................................57 Save modifications to the variants....................................................................................60 Create and assign a Topology Data File..........................................................................63 Create and assign a Load Data File ................................................................................66

Contents


LOAD FLOW CALCULATION...................................................................................................69 SHORT CIRCUIT CALCULATION..............................................................................................77 TRANSIENT STABILITY ANALYSIS .........................................................................................85 INTERFACES TO NEPLAN ...................................................................................................107 TIPS FROM THE PRACTICE....................................................................................................109

Asymmetrical Network Structure....................................................................................109 Load Flow.......................................................................................................................109

MENU OPTIONS .....................................................................................................................1 FILE .........................................................................................................................................1

New .....................................................................................................................................1 Open ...................................................................................................................................1 Close ...................................................................................................................................1 Save.....................................................................................................................................1 Save As ...............................................................................................................................2 Print ... ................................................................................................................................2 Print Preview ... ..................................................................................................................2 Print Setup ... ......................................................................................................................2 Page Setup ... ......................................................................................................................2 Print on One Page ... ..........................................................................................................2 Import ... .............................................................................................................................2 Export ... .............................................................................................................................3 Exit......................................................................................................................................3

INSERT.....................................................................................................................................4 Edit Options........................................................................................................................4 Elements..............................................................................................................................5 AC-Line and Bus.................................................................................................................5 DC and Asym. Line/Bus......................................................................................................6 Nested Block .......................................................................................................................7 Link .....................................................................................................................................7 Map.....................................................................................................................................7 Calibration Symbol.............................................................................................................7 Header ................................................................................................................................8 Color Legend ......................................................................................................................8 Line Legend ........................................................................................................................8 Control Circuit ...................................................................................................................8 Function Block Menu..........................................................................................................9

EDIT.......................................................................................................................................10 Undo .................................................................................................................................10 Redo ..................................................................................................................................10 Cut ....................................................................................................................................10 Copy..................................................................................................................................10 Paste .................................................................................................................................10 Delete................................................................................................................................10 Data ..................................................................................................................................11 Graphics ...........................................................................................................................14 Search ...............................................................................................................................15 Statistics............................................................................................................................16 Diagram Properties ..........................................................................................................16 Variant Properties ............................................................................................................26

VIEW .....................................................................................................................................27

Contents


Redraw..............................................................................................................................27 Variant Manager ..............................................................................................................27 Message Window ..............................................................................................................27 Symbol Window ................................................................................................................27 Ruler .................................................................................................................................27 Page Bounds .....................................................................................................................27 Grid...................................................................................................................................27 Snap to Grid......................................................................................................................28 Snape to Angle ..................................................................................................................28 Grid Properties.................................................................................................................28 Zoom Normal....................................................................................................................28 Zoom Percent....................................................................................................................28 Zoom Custom....................................................................................................................28 Zoom to Fit .......................................................................................................................28 Show Full Screen ..............................................................................................................29

ANALYSIS ..............................................................................................................................30 Calculation .......................................................................................................................30 Partial Network ................................................................................................................30 Parameter .........................................................................................................................31 Results...............................................................................................................................31

LIBRARIES .............................................................................................................................32 Libraries ...........................................................................................................................32 Symbol Library .................................................................................................................32 Set Active Library .............................................................................................................32 Copy to Diagram Library .................................................................................................32 Past from Diagram Library..............................................................................................32 Edit Diagram Library.......................................................................................................32 Import Old CCT Library...................................................................................................33

OPTIONS ................................................................................................................................34 Header ..............................................................................................................................34 Project Description...........................................................................................................34 Measurement and Size ......................................................................................................34 Calibrate...........................................................................................................................34 Insert Calibration Symbol ................................................................................................34 Make Backup ....................................................................................................................35 License ..............................................................................................................................35

WINDOW................................................................................................................................36 New Window .....................................................................................................................36 Cascade ............................................................................................................................36 Tile ....................................................................................................................................36 Arrange Icons ...................................................................................................................36

HELP......................................................................................................................................37 Help Topics.......................................................................................................................37 About Neplan ....................................................................................................................37

VARIANT MANAGER..............................................................................................................38 Variants ............................................................................................................................38 Diagrams ..........................................................................................................................38 All Elements ......................................................................................................................38 Elements............................................................................................................................39

TOOLBAR...............................................................................................................................40 MOUSE BUTTONS ..................................................................................................................41

Contents


Left Mouse Button.............................................................................................................41 Right Mouse Button ..........................................................................................................41

ELEMENT DATA INPUT AND MODELS ..........................................................................1 DATA INPUT DIALOGS OF NETWORK ELEMENTS .....................................................................1

Classification of Data in the Data Input Dialog ................................................................1 Element - Info .....................................................................................................................2 Element - Reliability ...........................................................................................................3 Element - User Data ...........................................................................................................3 Element - More…................................................................................................................4

STATION ..................................................................................................................................7 NODE.......................................................................................................................................9 DC NODE ..............................................................................................................................11 LINE.......................................................................................................................................12 ASYMMETRICAL LINE............................................................................................................20 DC LINE ................................................................................................................................26 LINE-COUPLING.....................................................................................................................28 PYLON ...................................................................................................................................33 COUPLER ...............................................................................................................................34 REACTOR...............................................................................................................................36 TRANSFORMER ......................................................................................................................38 ASYMMETRICAL TRANSFORMER............................................................................................51 THREE WINDINGS TRANSFORMER .........................................................................................55 FOUR WINDINGS TRANSFORMER ...........................................................................................62 SHUNT ...................................................................................................................................66 CONVERTER...........................................................................................................................70 SVC (CONTROLLED STATIC VAR COMPENSATOR)...............................................................78 STATCOM (STATIC COMPENSATOR) ...................................................................................82 TCSC ....................................................................................................................................85 UPFC ....................................................................................................................................89 NETWORK FEEDER.................................................................................................................92 SYNCHRONOUS MACHINE......................................................................................................95 ASYNCHRONOUS MACHINE .................................................................................................116 PS-BLOCK ...........................................................................................................................130 LOAD...................................................................................................................................134 DC LOAD ............................................................................................................................144 LINE LOAD ..........................................................................................................................146 USER DEFINED SCALING FACTORS ......................................................................................151 FILTER .................................................................................................................................155 SERIE-R-L-C (WITHOUT EARTH CONNECTION) ...................................................................160 PARALLEL-RLC ..................................................................................................................163 SERIE-E-RLC (WITH EARTH CONNECTION) ........................................................................166 DISCONNECT-SWITCH..........................................................................................................169 LOAD-SWITCH .....................................................................................................................171 CIRCUITBREAKER ................................................................................................................173 FUSE ....................................................................................................................................175 OVERCURRENT RELAY ........................................................................................................176 DISTANCE RELAY ................................................................................................................178 FREQUENCY RELAY.............................................................................................................179 VOLTAGE RELAY.................................................................................................................180 POWER RELAY.....................................................................................................................181

Contents


CURRENT TRANSFORMER ....................................................................................................182 VOLTAGE TRANSFORMER ....................................................................................................183 HARMONIC CURRENT SOURCE.............................................................................................184 HARMONIC VOLTAGE SOURCE ............................................................................................185 SERIES EQUIVALENT LF ......................................................................................................186 SERIES EQUIVALENT SC ......................................................................................................188 SHUNT EQUIVALENT LF ......................................................................................................190 SHUNT EQUIVALENT SC ......................................................................................................192 EARTH SWITCH....................................................................................................................194 SURGE ARRESTER................................................................................................................195 MEASUREMENT DEVICE ......................................................................................................196 CONTROL CIRCUIT CCT ......................................................................................................198 FUNCTION BLOCKS ..............................................................................................................200

LOAD FLOW ...........................................................................................................................1 CALCULATION PARAMETERS (LF)...........................................................................................1 RESULTS (LF)..........................................................................................................................6

Select Results ......................................................................................................................6 Show Results .......................................................................................................................6

THEORY OF LOAD FLOW CALCULATION................................................................................10 VOLTAGE DROP CALCULATION .............................................................................................16 REFERENCE VOLTAGES ..........................................................................................................18 DESCRIPTION OF THE RESULTS ..............................................................................................18 CONTINGENCY (OUTAGE) ANALYSIS ....................................................................................19 CALCULATION WITH DISTRIBUTED SLACK ............................................................................19 CALCULATION WITH LOAD BALANCE....................................................................................19 AREA/ZONE CONTROL (LF)...................................................................................................20

Wheeling not allowed (option disabled) ...........................................................................22 Wheeling allowed (option enabled) ..................................................................................24

ASYMMETRICAL LOAD FLOW ................................................................................................26 LOAD FLOW WITH LOAD PROFILES........................................................................................28

Calculation Parameters....................................................................................................28 Results...............................................................................................................................29 Theory...............................................................................................................................31

OPTIMAL POWER FLOW (OPF, TRANSMISSION) .......................................................1 CALCULATION PARAMETERS (OPF) ........................................................................................1 RESULTS (OPF) .......................................................................................................................7

Select Results ......................................................................................................................7 Show Results .......................................................................................................................7

DESCRIPTION OF THE PROGRAM ..........................................................................11 OBJECTIVE FUNCTION ...........................................................................................................12 RUNNING THE OPF PROGRAM...............................................................................................13

SHORT CIRCUIT....................................................................................................................1 CALCULATION PARAMETERS (SC)...........................................................................................1

Parameter ...........................................................................................................................1 Faulted nodes .....................................................................................................................3 Faulted lines .......................................................................................................................5 Special fault ........................................................................................................................5

RESULTS (SC)..........................................................................................................................9

Contents


Show Results .......................................................................................................................9 THEORY OF SHORT CIRCUIT CALCULATION...........................................................................15

A Comparison of the Methods: .........................................................................................17 Network Type IEC ............................................................................................................18 The Initial Short Circuit Current Ik" ................................................................................20 The Initial Short Circuit Power Sk"..................................................................................20 The Peak Short Circuit Current Ip ...................................................................................20 The Short Circuit Breaking Current Ib.............................................................................21 The Steady State Current Ik..............................................................................................22 The Thermal Short Circuit Current Ith.............................................................................23 The D.C. Component of Short Circuit Current iDC.........................................................23 The Asymmetrical Breaking Current Iasy ........................................................................23 The ANSI/IEEE-currents ..................................................................................................24 The symmetrical 0.5 cycles current ..................................................................................24 The asymmetrical 0.5 cycle current..................................................................................24 The symmetrical interrupting current (x cycles current)..................................................24 The symmetrical steady state (30 cycles) current.............................................................25 ANSI Standard C37.013 ...................................................................................................25

CALCULATION OF PARTIAL NETWORKS (SC) ........................................................................27

SELECTIVITY ANALYSIS....................................................................................................1 THE SELECTIVITY MODULE ......................................................................................................1

Installation..........................................................................................................................1 Functions of the independent E_SelModul.exe module......................................................1 Functions of the interactive graphic E_E32.exe ................................................................2

GENERAL.................................................................................................................................3 The menus and icons...........................................................................................................3 The list of elements .............................................................................................................3 System parameters ..............................................................................................................4 Project information.............................................................................................................4

INTEGRATION IN THE INTERACTIVE GRAPHIC ...........................................................................5 General ...............................................................................................................................5 Editing of protection device data........................................................................................5 Protection device response.................................................................................................7 Creating selectivity diagrams.............................................................................................7 Editing selectivity diagrams ...............................................................................................9 Parameters..........................................................................................................................9

THE CURRENT-TIME DIAGRAMS .............................................................................................10 General .............................................................................................................................10 Diagram properties ..........................................................................................................10 Saving the diagram or copying to the clipboard ..............................................................12

THE CHARACTERISTIC EDITOR ...............................................................................................13 The dialog window............................................................................................................13 Graphical input and editing of characteristics.................................................................14 Numerical input of characteristic points ..........................................................................15 Specifying standard characteristics..................................................................................15 Creating tolerance characteristics ...................................................................................16

THE MODULE EDITOR.............................................................................................................17 Editing of protection modules...........................................................................................17 Characteristics..................................................................................................................18 Coding of the setting ranges.............................................................................................22

Contents


Tolerances ........................................................................................................................22 Setup of protection modules .............................................................................................23

THE DEVICE EDITOR...............................................................................................................25 General .............................................................................................................................25 Adding new protection devices, wizards...........................................................................25 Editing of protection devices ............................................................................................26

THE DIAGRAM EDITOR ...........................................................................................................35 The selectivity diagram dialog window............................................................................35 Editing selectivity diagrams .............................................................................................36

DOCUMENTATION, PRINT OUTPUT .........................................................................................38 General .............................................................................................................................38 Library data......................................................................................................................39 Protection device setting tables and selectivity diagrams................................................39

DISTANCE PROTECTION....................................................................................................1 OVERVIEW...............................................................................................................................1 MENU OPTIONS FOR RELAYS...................................................................................................2 STARTER..................................................................................................................................4

Overcurrent ........................................................................................................................4 Under Impedance ...............................................................................................................4 Starter Characteristic L-L ..................................................................................................6 Earth Faults Detection .......................................................................................................8 Starter Characteristic L-E ..................................................................................................9

TRIPPING ...............................................................................................................................10 Impedance Stages for User Defined Relay .......................................................................10 Tripping Characteristic L-L .............................................................................................11 Tripping Characteristic L-E .............................................................................................11 Setting Parameters for Predefined Relays........................................................................11 ABB REL316.....................................................................................................................12 Siemens 7SA511, 7SA513 .................................................................................................13 AEG PD531, PD551, SD36..............................................................................................14 Back-up Protection ...........................................................................................................15 Automatic Impedance Setting ...........................................................................................16

TRIPPING TIME ......................................................................................................................19 Input..................................................................................................................................19 Automatic Time Setting.....................................................................................................19

VIEW .....................................................................................................................................20 Starter ...............................................................................................................................20 Tripping ............................................................................................................................20 Tripping Schedule.............................................................................................................21 Network Impedances (Impedance Path)...........................................................................22 Dimensions .......................................................................................................................22

PARAMETER (DP) ..................................................................................................................24 Global Parameter (DP) ....................................................................................................24 Relay-Specific Parameters ...............................................................................................26

TRIPPING SCHEDULES ............................................................................................................27 Build-up ............................................................................................................................27 Edit....................................................................................................................................27 Scrolling forward/backward.............................................................................................28

PROCEDURE FOR ENTERING A RELAY....................................................................................29 RELAY DOCUMENTATION......................................................................................................30

Contents


CHECKING THE RELAY SETTINGS ..........................................................................................33 Fault Locations.................................................................................................................33 Line Faults........................................................................................................................33 Evaluation According to Fault Locations ........................................................................33 Evaluation According to Relay Location..........................................................................36

HARMONIC ANALYSIS........................................................................................................1 CALCULATION PARAMETERS (HA)..........................................................................................1 THEORY OF HARMONIC AND AUDIO FREQUENCY ANALYSIS...................................................3 RESULTS (HA).......................................................................................................................11

Select Results ....................................................................................................................11 Results Table.....................................................................................................................11 Graphical Results .............................................................................................................13

MOTOR STARTING...............................................................................................................1 CALCULATION PARAMETERS (MS)..........................................................................................1 THEORY OF MOTOR STARTING CALCULATION ........................................................................2

Voltage Drop ......................................................................................................................4 RESULTS (MS).........................................................................................................................5

Select Results ......................................................................................................................5 Results tables ......................................................................................................................5 Graphical Results ...............................................................................................................5

NETWORK REDUCTION .....................................................................................................1 INTRODUCTION ........................................................................................................................1 SELECTION OF THE NETWORK TO BE REDUCED .......................................................................1 NETWORK REDUCTION FOR LOAD FLOW.................................................................................2 NETWORK REDUCTION FOR SHORT CIRCUIT............................................................................2

VOLTAGE STABILITY .........................................................................................................1 CALCULATION PARAMETERS...................................................................................................1

Sensitivity Analysis / Modal Analysis .................................................................................1 U-Q Curves.........................................................................................................................2 P-U Curves .........................................................................................................................2 Result Files .........................................................................................................................3

RESULTS ..................................................................................................................................4 Graphical Results ...............................................................................................................4 Result Tables.......................................................................................................................5

THEORY...................................................................................................................................6 Introduction ........................................................................................................................6 U-Q Sensitivity Analysis .....................................................................................................6 Q-U Modal Analysis ...........................................................................................................7 U-Q Curves.........................................................................................................................8 P-U Curves .........................................................................................................................9

SMALL SIGNAL STABILITY...............................................................................................1 CALCULATION PARAMETERS...................................................................................................1

Calculation .........................................................................................................................1 Result Files .........................................................................................................................1

RESULTS ..................................................................................................................................2 Graphical Results ...............................................................................................................2 Result Tables.......................................................................................................................3

Contents


THEORY...................................................................................................................................4

TRANSIENT STABILITY ......................................................................................................1 GENERAL REMARKS ................................................................................................................1

Simulation method ..............................................................................................................1 TERMS AND DEFINITIONS, PER-UNIT SYSTEM.........................................................................4

Terms and Definitions ........................................................................................................4 Per-Unit System..................................................................................................................4

NETWORK ELEMENTS ..............................................................................................................7 Controlled Admittance........................................................................................................7 Simulation...........................................................................................................................9 Maximum-minimum relays ...............................................................................................10 Distance protection...........................................................................................................11 Pole slip protection...........................................................................................................15 Overcurrent protection .....................................................................................................17

PROGRAM CONTROL ..............................................................................................................21 Simulation run and table output .......................................................................................21 Simulation parameters......................................................................................................22

SYMBOL LIBRARY ...............................................................................................................1 OVERVIEW...............................................................................................................................1 BASIC CONCEPTS.....................................................................................................................1

Symbols of Network Elements.............................................................................................1 Symbols of Protection Devices and Switches .....................................................................2 Symbols for "General Elements" ........................................................................................2 Disconnection Symbol and Flow Indicator ........................................................................2 Drawing Symbols................................................................................................................3

MOUSE BUTTONS ....................................................................................................................3 Select Mode.........................................................................................................................3 Drawing Mode....................................................................................................................3 Double-Click.......................................................................................................................3

GRAPHICAL ELEMENTS............................................................................................................4 Line Width (Symbol Library)..............................................................................................4

REFERENCES .........................................................................................................................1 ADDITIONAL REFERENCES.......................................................................................................1

APPENDIX............................................................................................................................527 THE STRUCTURE OF THE IMPORT-/EXPORT-FILES ...............................................................527

EDT-File.........................................................................................................................527 NDT-File.........................................................................................................................533 Measurement Data / Load Factor Files .........................................................................535 Harmonic limit file..........................................................................................................536

Contents


Tutorial


Tutorial

Introduction

NEPLAN is a very user friendly planning and information system for electrical-, gas- and water-networks. All menu options and calculation modules are described in details in the following chapters. To get to know NEPLAN in a quick and easy way, we recommend you to follow this tutorial. The program will be explained by examples and we show how to start a new project and how to build a small power system. That means, that the user will learn how to enter the elements graphically, how to enter data, how to use libraries, how to run calculations and how to present the results in a manner adapted to the objectives of the analysis. As mentioned, the Tutorial is a first step to get used to the NEPLAN software. For details about models of elements, data input or calculation inputs, please consult the respective chapters of the User's Guide or use the context sensitive Online Help.

Tutorial

1-2 NEPLAN User's Guide V5

The User Interface

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Fig. 1.1 Window features in the user interface The numbers indicate the following window features: 1. Titlebar 5. Variant Manager 2. Menu option bar 6. Symbol Window 3. Toolbar 7. Message Window 4. Workspace with diagrams and data tables 8. Status bar

Toolbar All command buttons are equipped with balloon help texts, which pop up when the cursor is held still at the button for a moment without pressing any keys. Many commands, which can be accessed in the Toolbar, may be found as well in the respective menus. Others, mainly the graphical commands can only be accessed in the Toolbar.

Tutorial


Workspace In the Workspace the different diagrams can be opened. The same diagrams may be used for entering the network, building control circuits or sketching drawings.

Variant Manager The Variant Manager gives a good overview of the open projects and variants. New projects and variants may be managed, what means that they can be deleted, added, activated or deactivated. From the Variant Manager, the user can switch to the Diagram Manager, which administrates the open Diagrams with its graphic layers.

Symbol Window The Symbol Window contains all element symbols available. Apart from the standard symbol for some elements there exist other symbols with a different graphical appearance but exactly the same characteristics. New symbols also can be created or existing symbols may be modified with the Symbol Library.

Message Window The message window is the channel to communicate with the user. It supplies information about the executed processes, error messages and further information.

Tutorial


The Online Help

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Fig. 1.2 How to call the Online Help The figure above shows how to call the Online Help. With button 1) a context sensitive help is called, what means, that after pressing this button, the user may click on the feature or dialog for which he needs more information. Selecting the Help Topics in the menu Help or pressing F1, the user can get more information with a topic or with an index search.

Tutorial


Data Organization

Fig. 1.3 Data Organization of NEPLAN The figure above shows the data organization of NEPLAN. The NEPLAN directory contains the following folders:

Bin: contains executable and control files Dat: contains Examples and NEPLAN projects Hardlock: contains the executable file for the Hardlock driver HTML Help: contains the HTML Help files Lib: contains NEPLAN Libraries Manuals: contains the manuals as pdf files Ramses: contains files of the module Ramses temp: contains temporary files user: contains User files and projects

During the installation process, an entry in the operational system registry will be made by NEPLAN. It's the information about where the program can find the different folders to save and read data.

Tutorial


The Basic Elements of NEPLAN

To understand the NEPLAN environment, it is essential that certain concepts used in the system are described:

Network Feeder

Node Node Node

Disconnect, Load Switch

Load

Logical Switches

Station

Fig. 1.4 One line diagram with network components An electrical power system consists of nodes and elements.

Nodes A node is the connection point of two elements or a location, where electrical energy will be produced or consumed (generator, load). A node is described by its

• Name, • nominal system voltage in kV, • zone and area, • type of node (main bus bar, bus bar, sleeve, special node), • description,

The nominal system voltage Un is the line-to-line voltage, for which a power system is designated and on which several characteristics of the power system has been referred. In NEPLAN the nominal system voltage of the nodes must be entered during the node data input. Every voltage is given as a line-to-line voltage (delta voltage). It is not necessary to past a node in between all elements. They may also be connected directly with a link. In this case no node results will be presented and not more than two elements can be connected together in the same point.

Tutorial


Elements An element corresponds to a network component, like e.g. line, transformer or electrical machine. There are active elements and passive elements. An element is described topological by a starting and an ending node. For three windings transformers a third node must be given. The elements will be described electrical by

• the rated current, rated power and rated voltage and • its parameters, such as losses, reactances, ...

In NEPLAN these parameters are entered with input dialogs. The active elements are network feeders, asynchronous machines, synchronous machines and power station units. A network feeder represents a neighboring network. The passive elements are lines, couplings, switches, reactors, two and three windings transformers, shunts and loads. The loads can also be entered along a line without entering nodes (line loads).

Modeling of Active Elements For a short circuit calculation the active elements are modeled with the help of their subtransient reactance. For a load flow calculation these elements will be represented by resistive and reactive powers (PQ-nodes) or by voltage magnitude and angle (slack nodes) at the node. The network feeder usually will be modeled as a slack node.

Protection Devices, Current and Voltage Transformers Protection devices (overcurrent relays, distance protection relays, circuit breakers) and current or voltage transformers are associated with the built-in node and the switching element. They have no influence on the load flow and short circuit calculation. Only their limits are checked during the calculation. These elements are used in the relay coordination modules.

Station A station can contain several nodes and has no meaning for the calculations or for protection device coordination. It will only be used in relation to the database.

Tutorial


Symbol For each element type there are different symbols in the Symbol Window. Choose the one you want to past in the diagram. A Symbol Library is included in the NEPLAN package, where user defined symbols may be created.

Switches In NEPLAN the switches are used to change the network topology (switching on/off elements). There are two different types of switches:

• physical switch and • logical switch.

Physical switches are couplings, circuit breakers and disconnect or load switches. Logical switches are fictive switches, which are assigned to all elements by the system. A line, for example, has two logical switches, one at the starting and one at the ending node. A physical switch has no logical switch, because it will already be switchable. During the input of a network, the physical switches can be neglected, because switching can be done with the help of the logical switches. This has a disad-vantage, when a line leads to a double bus bar system. Switching from one bus bar to an other, the user has to change the starting or the ending node of the line. If the user enters two disconnect switches (one to each bus bar) with an additional node in between, the switching can be done with the disconnect switches. The physical switches can be reduced during the calculation (see the Parameters dialog of the respective calculation modules).

Zones and Areas Zones and areas are network groups, which may be defined. This means, that every element and node belongs to a zone and to an area. An area normally includes one or more zones. For load flow calculation it's possible to define transactions between zones and between areas. Each zone and area may be presented in a different color. In Step 4 - E it will be explained how to define zones and areas.

Partial Networks Unlike zones and areas, a partial network is an independent network. A partial network has no connections to any other networks. You can make partial networks by opening logical or physical switches. It is possible to color each partial network differently (see below).

Tutorial


Network feeder

Node NodeNode

Disconnect,Load switch

Line

logical switch "open"

Station

Partial network 2

Partial network 1

Fig. 1.2 Partial networks

Tutorial


Step 1 – Create a new project

To create a new project, after having started the program, click on the menu "File – New".

1. Enter the location or directory for saving the project. Pressing the button "…", you can choose the directory.

2. Enter the project name. 3. Choose the network type: Electric, Water or Gas. 4. If you wish, you may enter a project description. 5. Choose the diagram size and the page orientation. 6. Press the OK button.

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Fig. 1.5 Create a new project The figure below shows the user interface after having created the new project.

a. The titlebar shows the name of the active project. b. One diagram is open for the rootnet. c. The variant manager shows the project tree, which consists at the moment

of only one rootnet.

Tutorial


a

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Fig. 1.6 After creating a new project

Tutorial


Step 2 – Enter a small network

In this step, you'll enter nodes and elements to build a small electrical network. The Symbol window allows you to choose the desired element symbol in an easy way. You can start entering any element you want. It is not necessary to enter first the nodes, because the new philosophy of NEPLAN is to first enter the elements and nodes independently in the diagram, and then to connect them with a link. Only lines can't be entered independently. They need connection points, which are nodes or other elements. It's not necessary to enter a node between all elements, because the elements can be interconnected directly with a link. However, if the user wants to see the node results, he has to enter the node graphically.

Input data We will draw the following network:

Fig. 1.7 Network to be entered in NEPLAN The necessary parameters are all listed in the following tables.

Tutorial


Network Feeder: Name Sk''max Ik''max R(1)/X(1) Z(0)/Z(1) C1 Sk''min Ik''min R(1)/X(1) Z(0)/Z(1) LF- U oper Uw oper Poper Qoper

- MVA kA max max uF MVA kA min min Type % Deg MW Mvar

NETZ 1500 3.936 0.1 1.667 0 1500 3.936 0 0 SL 100 0 0 0

Lines: Name Length Numb Units R(1) X(1) C(1) G(1) R(0) X(0) C(0) Ir min Ir max Red. fact. Q mm2

km Ohm/.. Ohm/.. uF/... uS/... Ohm/.. Ohm/.. uF/... A A mm2

LEIT. 1 1.16 1 Ohm/km 0.103 0.403 0.009 0 0.150 1.400 0.005 0 90 1 0

LIN 2- 4 1.16 1 Ohm/km 0.103 0.403 0.009 0 0.140 1.499 0.005 0 90 1 0

LIN 2- 3 0.59 1 Ohm/km 0.103 0.403 0.009 0 0.140 1.599 0.005 0 70 1 0

LIN 4- 8 0.20 1 Ohm/km 0.113 0.410 0.009 0 0.150 1.599 0.004 0 100 1 0

LIN 3- 8 0.37 1 Ohm/km 0.113 0.413 0.009 0 0.153 1.619 0.004 0 75 1 0

LIN 3- 9 0.16 1 Ohm/km 0.113 0.413 0.009 0 0.154 1.639 0.004 0 60 1 0

LIN 7- 6 1.61 1 Ohm/km 0.066 0.382 0.010 0 0.085 1.459 0.004 0 400 1 0

LIN 5- 2 7.80 1 Ohm/km 0.091 0.415 0.009 0 0.130 1.659 0.004 0 200 1 0

LIN 5- 6 11.90 1 Ohm/km 0.141 0.413 0.009 0 0.160 1.649 0.004 0 190 1 0

LIN 8- 7 19.10 1 Ohm/km 0.112 0.400 0.009 0 0.144 1.587 0.005 0 200 1 0

Loads:

Name LF Type P Q Domestic Units Units

V_ZWOELF PQ 5 4 0 HV

V1 PQ 2 2 0 HV

Synchronous Machines:

Name Sr Ur pUr cosphi xd sat xd' sat xd'' sat x(2) x(0) Ufmax/ur Ikk - MVA kV % - % % % % % - kA

GEN 1 45 8.5 0 0.85 160 0 20 20 20 2 0

Name mue RG Turbo Amort. Winding Unit Geneator Motor LF-Type P oper Q oper

- - Ohm - - - - - MW Mvar

GEN 1 0 0 1 1 1 0 PQ 40 10

Transformers:

Name From To Vector Unit Comp. Sr Ur1 Ur2 ukr(1) uRr(1) ukr(0) uRr(0) Node Node Group Transf. Winding MVA kV kV % % % %

TRA8 -12 EIGHT TWELVE YD,05 0 0 60 65 16 10 0 10 0

TRA6 -13 SIX THIRTEEN YD,05 0 0 140 65 8.5 10 0 10 0

TRA8 -11 EIGHT ELEVEN YD,05 0 0 12 65 5.2 10 0 10 0

TRA9 -10 NINE TEN YD,05 0 0 6 65 5.2 8.46 0 8.46 0

TRA1-2 ONE TWO YY,00 0 0 200 220 65 9 0 9 0

Name I0 Pfe U01(0) U02(0) Earthing RE1 XE1 ZE1 active Earthing RE2 XE2 ZE2 active

% kW % % primary Ohm Ohm % secondary Ohm Ohm %

Tutorial


TRA8 -12 0 0 0 0 impedance 0.1 0 100 impedance 6 0 100

TRA6 -13 0 0 0 0 direct 0 0 100 direct 0 0 100



TRA1-2 0 0 0 0 direct 0 0 100 impedance 1 35 100

Name On-load Tap side Controlled Tap act Tap min Tapr Tap max Delta U Beta U Uset Pset Sr min Sr max

Tapchanger bus % ° % % MVA MVA

TRA8 -12 0 Primary Primary 0 0 0 0 0 0 0 0 60 60

TRA6 -13 0 Primary Secondary 0 0 0 0 0 0 0 0 140 140

TRA8 -11 0 Secondary Primary 0 0 0 0 0 0 0 0 12 12

TRA9 -10 0 Secondary Primary 0 0 0 0 0 0 0 0 6 6

TRA1-2 1 Primary Secondary 0 -10 0 10 2 0 100 0 200 200

Asynchronous Machines: Name From Pr Sr Ur Ir cosphi eta Ia/Ir Number Pole- Conv.- cosphi Ma/Mr Mk/Mr Rm sr

Node MW MVA kV A - - - - pairs Drive start - - Ohm %

U3 5.2 ELEVEN 5 6.6489 5.2 0.738 0.8 0.94 5 1 1 1 0.3 0.9 2.2 0 2

U1 5.2 TEN 5 6.6489 5.2 0.738 0.8 0.94 5 1 1 1 0.3 0.9 2.2 0 1.8

Name J H LF type P oper Q oper ANSI Load M0 M1 M2 M0,1,2 Model

kg*m2 s - MW Mvar factor torque in Nm

U3 5.2 100 0.742 PQ oper 2 1 1.5 Parabola 4500 0 7000 1 3. Order

U1 5.2 100 0.742 PQ oper 4 3 1.5 Parabola 3500 0 7000 1 3. Order

Nodes:

Name Node Un Frequ. Umin Umax Ir Ipmax Type kV Hz % % A kA

THREE Busbar 65 50 0 0 0 0

FOUR Busbar 65 50 0 0 0 0

TEN Busbar 5.2 50 0 0 0 0

TWELVE Busbar 16 50 0 0 0 0

SEVEN Busbar 65 50 0 0 0 0

ELEVEN Busbar 5.2 50 0 0 0 0

THIRTEEN Busbar 8.5 50 0 0 0 0

ONE Busbar 220 50 0 0 0 0

TWO Busbar 65 50 0 0 0 0

EIGHT Busbar 65 50 0 0 0 0

SIX Busbar 65 50 0 0 0 0

FIVE Busbar 65 50 0 0 0 0

NINE Busbar 65 50 0 0 0 0

Enter the network

Tutorial


Enter an element 1. To draw an element from the symbol window, click on it, hold the mouse

button pressed, drag the symbol to the diagram and drop it. 2. A data-input-dialog for the element appears. 3. Enter a name for the element. 4. Enter the element parameters. 5. Press the OK-button when finished.

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Fig. 1.8 Enter an element Enter a node

6. To enter nodes, click on one of the node button in the Toolbar. 7. Click once in the diagram for a round-point-node. To draw a bar-node, click

in the diagram, but hold the mouse button and move the mouse to define the length of the bar-node, then leave the mouse button.

8. A data-input-dialog for the node appears. 9. For the node data at least the nominal system voltage and frequency are

required. 10.Press the OK-button when finished.

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Fig. 1.9 Enter a node Enter a link

11.To interconnect elements with elements or with nodes, use the links. Press on the link-button.

12.First click on one end of the element. 13.Then click on the node to finalize the link.

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Fig. 1.10 Interconnecting the elements with Links Build up the whole network (Hint for entering lines)

14.Build up the network in the same manner as explained before. To enter lines you need nodes where to connect them.

15.For entering lines press on the Line-button. 16.Click on the starting-node. 17.Click in the diagram, wherever you wish to have supporting points. 18.Click on the ending-node 19.Enter the line data in the appearing dialog. 20.Press OK when finished.

Tutorial


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Fig. 1.11 Enter a line Enter a text field

21.Click on the text-button. 22.Click in the diagram. The text field will be inserted and you may enter a text.

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Fig. 1.12 Enter a text field

23.To change the properties of the text field, select it and press the right mouse button.

24.In the appearing pop-up menu choose Graphic Properties and the dialog appears.

25.You may change the text and the font or apply a frame and colors.

Tutorial


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Fig. 1.13 Change the text field properties

Test your network After having entered the network with all nodes and elements data, you should check if all elements are linked and all data is entered correctly. For this reason perform a load flow calculation with "Analysis – Load Flow - Calculation". Watch out for any error messages in the Message Window and correct your network, till the load flow calculation is running successfully. In case that you get an error message for a certain element, the elements ID will be indicated. There is a feature in NEPLAN to search this element in an easy way: Search for an element

1. Choose the Search-feature in the Edit-menu. 2. Select the search-criteria. In this case choose “Id”. 3. Enter the ID of the element you are looking for. 4. Press the button Find Next.

Tutorial


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Fig. 1.14 Search for an element

5. The program will move the view of the network, so that the searched element is displayed in the center with an orange frame around it.

6. Use the button Show Dialog to show the data input dialog of the marked element.

7. Enter an other ID to look for an other element. 8. Press Cancel to finish the Search.

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Fig. 1.15 Find the element

Tutorial


Step 3 – Insert Header, Save, Print, Exit

Insert Header In every diagram a header may be inserted and its data can be edited.

1. Insert a header with "Insert - Header". 2. Click in the diagram to past the header.

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Fig. 1.16 Insert a header into the diagram

3. With "Options – Header" a dialog with the header text lines appears. 4. The text lines may be modified.

Tutorial


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Fig. 1.17 Modify the header lines

5. With "Options – Project Description" a respective dialog appears. 6. You may modify the project description.

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Fig. 1.18 Modify the project description The project name and the variant name are displayed automatically in the header.

Save the network From time to time the network has to be saved to avoid data loss. Generally just do it by pressing the Save-Icon or with "File - Save". In the following it's shown how you save a network for the first time or how to save it with a different name.

1. Choose "File – Save as".

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Fig. 1.19 Save a project

2. Choose the directory, where the project should be saved. 3. Enter the file-name. 4. Click on the button "Save"

Tutorial


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Fig. 1.20 Enter the file-name

Print the diagram Use Page Setup, Print Setup and Print Preview to adjust all settings before you Print. To print the diagram on one page activate the option "Print on One Page". If this function is not activated, the diagram may be printed on several pages.

1. Use "Page Setup" for settings of the paper size and margins. 2. Use "Print Setup" for printer settings. 3. Make a print preview from the diagram. You may print from the preview

window. 4. Print the diagram.

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Fig. 1.21 Print the diagram

Tutorial


Close and open projects Projects may be opened and closed without quitting the program. Several projects can be open at the same time, they will be displayed in the variant manager.

1. Make a right-mouse-button click on the project symbol in the variant manager. A popup menu appears.

2. Choose "Close Project" to close the respective project. The same is possible with "File - Close".

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Fig. 1.22 Close a project

3. Open an other, already existing project with "File – Open"

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Tutorial


Fig. 1.23 Open a project

4. To exit the program use "File – Exit"

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Fig. 1.24 Exit the program

Tutorial


Step 4 – Use of Diagrams, Layers, Areas and Zones

In this step you will learn how to handle diagrams and graphic layers and you'll define areas and zones. We use the example network MyProject.nepprj, entered in Step 2.

Use of Diagrams For a certain project, the network may be entered in different diagrams. With the help of this function, the user can for instance enter the high voltage network in one diagram and the low voltage network in several other diagrams. The high voltage network could also be divided into several diagrams. An other use is zooming into stations. In the general diagram the station can be drawn as a "black box" and in an other diagram the station can be drawn in detail with all protection and switching devices. In this step, we will learn the handling of diagrams in a project.

Rename a Diagram The following figure explains the procedure to rename the single diagram in our project, which actually has the name Diagram 0.

1. Select the diagram manager. 2. Double click on the existing "Diagram 0" and the Diagram Properties dialog

appears. 3. The name can now be changed to "MV-Network". 4. If you wish, insert a diagram description.

Tutorial


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Fig. 1.25 Change of diagram name

Define a new diagram A low voltage network for the substation STAT-LV shall be inserted in an other diagram. We'll define this new diagram, like shown in the figure below:

1. Make a right-mouse-button click on the Diagram Manager and choose "Insert new Diagram". The Diagram Properties dialog appears.

2. Enter the name of the new diagram. 3. If you wish, insert a diagram description.

Tutorial


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Fig. 1.26 Insert a new diagram After having closed the Diagram Properties by clicking the OK-button, the following diagram structure is displayed.

Fig. 1.27 Rootnet with two diagrams

Tutorial


To display a diagram, check its checkbox and uncheck it for closing. The last checked diagram is the active one and can be edited.

Enter a low voltage network Activate the diagram "LV-network" and draw the following network.

Fig. 1.28 LV-Network, drawn in the new diagram The necessary parameters are all listed in the following tables. Lines: Name Type Length Number Units R(1) X(1) C(1) G(1) R(0) X(0) C(0) Ir min Ir max Red. Q

km Ohm/..

. Ohm/..

. uF/... uS/... Ohm/... Ohm/... uF/... A A fact. mm2

N-L2 KS 3x150/150 0.03 1 Ohm/km 0.1240 0.072 0 0 0.508 0.115 0 0 360 1 150

N-L1 KS 3x240/240 0.02 1 Ohm/km 0.0754 0.072 0 0 0.308 0.119 0 0 470 1 240

Loads:

Name From node LF Type P Q Domestic Units Units

N-V3 N3 PQ 20 10 0 LV

N-V2 N2 PQ 40 30 0 LV

Tutorial


Transformers:

Name Type From To Vector Unit Comp. Sr Ur1 Ur2 ukr(1) uRr(1) ukr(0) uRr(0)

Node Node Group Transf. Winding MVA kV kV % % % %

TRAFO-NS 16/0.4 KV 630 KVA TWELVE NS_SS_N1 DY,07 0 0 0.63 16 0.4 5.24 1.12 5.24 1.12

Name I0 Pfe U01(0) U02(0) Earthing RE1 XE1 ZE1 active Earthing RE2 XE2 ZE1 active

% kW % % primary Ohm Ohm % secondary Ohm Ohm %

TRAFO-NS 0 0 0 0 direct 0 0 100 direct 0 0 100

Name On-load Tap side Controlled Tap Tap Tapr Tap Delta U Beta U Uset Pset Sr min Sr max

Tapchanger bus act min max % ° % % MVA MVA

TRAFO-NS 0 Primary Secondary 0 0 0 0 0 0 0 0 0.63 0.63

Nodes:

Name Node Un Frequ. Umin Umax Ir Ipmax Type kV Hz % % A kA

N3 Sleeve 0.4 50 0 0 0 0

N2 Sleeve 0.4 50 0 0 0 0

NS_SS_N1 Busbar 0.4 50 0 0 0 0

Enter an element more than once in a project Elements may be represented graphically as many times as you want in the same project. Mainly this makes sense, when you wish to see the same element in different diagrams, like in our case. The substation STAT-LV, where the low voltage network is connected, shall be represented in the LV- and in the HV-diagram to connect the two networks. It concerns the substation symbol and the node TWELVE. To draw the node TWELVE a second time follow the instructions:

1. Select the node symbol as usual and draw the node in the diagram. 2. In the appearing Input-dialog, select the Info-tab. 3. Press the button beside the name field. 4. Select an already existing node from a list. 5. By pressing the OK-button, the data of the respective element will be

adopted.

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Fig. 1.29 Enter an already existing element again in the same project. After you entered the whole low voltage network, perform a Load Flow calculation to proof the entered data and the connections of the elements.

Use of graphic layers To each diagram, any number of graphic layers may be assigned. The user can decide, which graphic layers of a diagram shall be displayed simultaneously. The figure below shows the principle of diagrams and graphic layers.

Tutorial


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Graphic Layer 1-3 of Diagram 1

Diagram 2

Diagram 1

Graphic Layer 1-2 of Diagram 2

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Fig. 1.30 Assignment of graphic layers to diagrams In each graphic layer any number of graphic elements, electric elements or nodes can be entered or bitmaps imported. Before you insert a new component, you can choose the graphic layer, to which it should belong. The graphic layers can be displayed selectively. For example, it's possible to use different layers for current transformers and relays. If you are doing load flow calculation, you could switch off the layer for the relays. If you are doing relay coordination you can switch on the relay layer. In our example we'll introduce a second graphic layer for the HV-diagram with the name Areas/Zones. In the new graphic layer, we will draw the regions of network areas and zones. We then have the possibility to display or not this graphical input, by switching on or off the respective graphic layer.

Insert new graphic layers Follow the instructions to insert new graphic layers:

1. In the Diagram Manager make a right-mouse-button click on the diagram symbol "HV-Network".

2. In the menu choose "Insert new Graphic Layer".

Tutorial


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Fig. 1.31 Add a new graphic layer to the diagram "HV-Network" 3. In the "Graphic Layer Parameters" – dialog, enter the name of the graphic

layer. 4. If you wish, you may write a description.

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Fig. 1.32 Enter the graphic layer parameters Finally the Diagram Manager will look like this:

Tutorial


Fig. 1.33 Diagram Manager after entering the new graphic layer

Enter drawings in the new graphic layer To be able to edit a graphic layer, it has to be activated.

1. Activate the new graphic layer Areas/Zones of the diagram HV-Network, either by mouse click in the checkbox or by choosing the right option in the menu, which appears with a right-button mouse click.

2. Draw the regions for an area and a zone and write a text, like in the figure below, by using the graphical tools in the toolbar.

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Fig. 1.34 Input for the graphic layer "Areas/Zones" of the diagram "HV-Network" Actually, both graphic layers (GrLayer 0 and Areas/Zones) are shown. Switch off the graphic layer "Areas/Zones", so that only the network is displayed.

1. To be able to switch off the graphic layer Areas/Zones, it mustn't be active. For that reason, activate the other graphic layer.

2. Right-mouse-button click on the symbol of the "Areas/Zones" layer. 3. Unselect the "Show Graphic Layer" option.

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Fig. 1.35 Switch off the graphic layer "Areas/Zones" Now, the graphical elements we entered before disappeared and only the network is visible. A red cross over the graphic layer symbol indicates, that the "Areas/Zones" layer is not shown, respectively switched off:

Tutorial


Fig. 1.36 Only the graphic layer "GrLayer 0" is shown

Define and assign Areas and Zones Areas and zones are both network groups and can be defined by the user. Every element and node belongs to one zone and to one area. An area normally includes one or more zones. For load flow calculation it is possible to define transactions between different zones and between different areas. When creating a new project, there is one area and one zone predefined and every entered element is assigned to these network groups. After an element has been entered its area and zone may be changed. There are different possibilities to assign an area or/and a zone to network elements. They will be explained below. In general areas and zones have to be defined first, before they can be assigned to elements.

Define areas and zones To define areas and zones, choose "Edit – Variant Properties".

1. Select the "Areas" tab first. 2. In the list, there exists only the predefined area. To add a new area click on

the respective button. 3. Enter the name of the area 4. Choose a color. 5. Press the OK button.

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Fig. 1.37 Define a new area “Area_red” Let us change the color of Area 1.

1. Select Area 1 in the Area tab. 2. Click on the Properties button. 3. Change the color. 4. Press the OK button.

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Fig. 1.38 Change the properties of Area 1 In the same manner define the zone Zone_motors:

1. Select the "Zones" tab first. 2. To add a new zone click on the respective button. 3. Enter the name of the zone and the color. 4. Different scaling factors for a zone may be defined. 5. Press the OK button.

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Fig. 1.39 Define zones Now, zones and areas are defined and they can be assigned to the elements. You have several possibilities to do it.

Assign areas and zones to the elements, one by one As shown below, for every single element you may choose independently a zone and an area, which have been defined previously.

Tutorial


Fig. 1.40 Assign an area and a zone to an element

Assign areas and zones to a group of elements An other, much easier method is to mark a group of elements and to assign to all of them an area or/and a zone.

1. Mark a group of elements by using the mouse to put up a selection window or/and by clicking on different elements, while keeping the Shift-key pressed.

2. Choose "Assign Areas/Zones" and the "Assign Properties" – dialog will appear.

3. In the "Assign Properties" – dialog check the Area-box to assign an area to the elements. If you want to assign as well (or only) a zone to the elements, just mark the respective checkbox.

4. You now can select the name of the area, to which the element should belong to.

Tutorial


5. As we marked a group of elements for the assignment, we choose the option "Assign to graphical selection".

6. Press the OK button.

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Fig. 1.41 Assign an area (or/and a zone) to a group of elements As a control, you can now open the Info tab of a Data Input Dialog of an element that belongs to this area and you'll notice that the area name has been changed.

Assign areas and zones to all elements of a partial network For this procedure you first have to create a partial network. This means, a part of the network has to be disconnected from the rest.

1. Disconnect the part of the network, which you want to assign to an area or/and zone. A partial network is built.

2. Get to the Assign Properties dialog by the menu option "Edit - Data – Assign Areas/Zones".

3. Select Area (or/and Zone) and choose the respective name.

Tutorial


4. Check the box "Assign to all elements of selected partial network" and select the ID of the partial network. If you don't know this ID, open the Data Input dialog of one element of this partial network and get it of the Info tab.

5. By pressing the OK button, the assignment will be finalized. Don't forget to reconnect the partial network.

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Fig. 1.42 Assign an area (or/and a zone) to a partial network You now have the possibility to color the network according to the different areas or zones.

1. Get to the Colors tab of the Diagram Properties with "Edit – Diagram Properties".

2. Select "Network Areas" for a coloration of the network according to areas. 3. Press the OK button and the coloration of the network will change.

Tutorial


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Fig. 1.43 Network coloration according to areas

Tutorial


Step 5 – Create and use Libraries

The NEPLAN Library File *.neplib may contain many element libraries, which are sorted by element type. In the following we explain how to create new libraries, how to copy library data to an element and how to export data from an element to a library.

Create a new Library The following steps explain how to create a new element library:

1. Choose "Libraries" in the menu "Libraries". The NEPLAN Library Application appears.

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Fig. 1.44 Open the Library Application

2. Select "File - New" to create a new Library File. 3. Enter the Library File name.

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Fig. 1.45 Create a new Library File

4. Select "Library – New Library" to create a new library. 5. Choose the element type, for which a library has to be created.

Tutorial


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Fig. 1.46 Create a new library

6. A new library appeared in the library tree. The libraries are sorted by element type.

7. Change the name of the new library

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Fig. 1.47 Change name of library

8. Insert a new Library Element (type) by selecting "Library Element - New".

Tutorial


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Fig. 1.48 Insert new library element

9. A new library element appeared in the library "50MVA".

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Fig. 1.49 New library element in the library "50MVA"

10.Change the type name of the library element. 11.Enter the data for the new library element. 12.If you wish, enter additional library elements. 13.If you wish, enter other libraries. 14.When finished, close the Library Editor with "File-Close".

Tutorial


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Fig. 1.50 Enter library data

Import data from a library When a network element has been entered in the diagram and you wish to copy the data from an element type of the library, proceed as follows:

1. In the Params tab of the Element-Data-Input-Dialog, press the button "…".

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Fig. 1.51 Copy the data from an element type of the library

Tutorial


2. Choose the NEPLAN-Library-File, where the respective element type can be found.

3. Select the element type in the respective library. 4. To copy the data from the library to your element, click on the OK-button.

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Fig. 1.52 Choose the element type

Update your network data with a library type In case that the data of a certain element type in the library has been changed, you have the possibility to update this data easily in all network elements, which are of the same type.

1. Click on the Library button in the Data-Input-Dialog of an element with the respective element type.

2. In the Library dialog, select the element type. 3. Press the button "Update Data with Modal Type" to update the data in every

network element with the same type. 4. Proceed in the same way to update other elements with a modified type.

When finished, click the OK-button to close the dialog.

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Fig. 1.53 Update all elements of a certain element by the library data

Export data to a library In case that you entered data in the Data-Input-Dialog of an element and you want to create an element type of this data in a library, proceed as follows.

1. Enter a element type name in the element dialog. 2. Click on the Export-button in the Data-Input-Dialog of the element, to call

the Library dialog. 3. Choose the Library File, whereto export the data. 4. If you want to create a new library, press this button (A new element type

can be inserted in a new or in an already existing library). 5. Select the library, whereto the new element type should be added. 6. To finalize, click the OK-button.

Tutorial


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Fig. 1.54 Export data of an element to the library

7. When you open the Library dialog again, you'll recognize the new library element.

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Fig. 1.55 New element type

Tutorial


In the same manner you may also update an already existing element type in a library. Select the library in which this element type already exists and press OK. You then will be asked if the existing element type shall be overwritten.

Tutorial


Step 6 – Define variants

For calculating different cases, NEPLAN has the possibility to create different variants of the rootnet and to combine them with topology and loading data files. The following figure shows the principle.

BASE or ROOT

VAR-1 VAR-2 VAR-3 VAR-4

VAR-12

VAR-132

VAR-31 VAR-42

VAR-43 VAR-131 VAR-133

BASE CASE or ROOT NETWORK

Topology

Topology-1

...

Loading

Loading-1

Loading-2

Loading-3

...

Variants

Topology-2

Topology-3

Fig. 1.3 Variant Management System with NEPLAN The variants are saved together with the Rootnet in the project file (.nepprj), for topology and loading data separate files will be defined. When activating a variant, assigned topology and loading files will be opened automatically. In this step 4, you'll get in contact with the concept of variants. In the following, different variants will be defined.

Tutorial


Insert new Subvariants Variants first have to be created in the variant tree, before the modifications for the different variants can be saved. Several variants will be defined.

1. Make a right-mouse-button click on the rootnet symbol in the Variant Manager

2. Choose "Insert new Subvariant"

Mcontr32.dll

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Fig. 1.56 Insert new Subvariant

3. A "Variant Properties" dialog appears. 4. Enter a Name for the new variant and if you wish, a description.

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Fig. 1.57 Enter name and description

5. “Variant replacement” is displayed in the variant tree.

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Fig. 1.58 "Variant replacement" appears in the variant tree

6. Define an other variant “Variant additional” in the same way as before.

Tutorial


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Fig. 1.59 Define a variant "Variant additional"

7. Define two subvariants (Variant a and Variant b) of "Variant replacement"

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Fig. 1.60 Define subvariants "Variant a" and "Variant b"

Tutorial


Save modifications to the variants A variant tree now has been created, but all variants still contain the same data. Now we will modify the different variants.

1. Activate “Variant replacement” by clicking on the checkbox. 2. As a modification for this variant, change the length and Ir of LIN 7-6.

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Fig. 1.61 Realize the modifications in "Variant replacement"

3. Deactivate “Variant replacement” by clicking on the checkbox. This is necessary if you wish to edit next a variant of the same tree branch.

4. You'll be asked, if you want to save the modifications in “Variant replacement”. Click on YES.

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Fig. 1.62 Save the modifications of “Variant replacement”

5. Activate Variant a 6. Notice that the modifications carried out in “Variant replacement” have also

been realized in Variant a (in this case the length and Ir of the LINE 7-6). 7. Call the data input dialog of LINE 8-7 by double clicking the line. 8. Modify the data of the resistance.

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Fig. 1.63 Realize modifications for Variant a

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9. Activate Variant b. As you may notice, the Variant a can still be activated,

because the two open variants are not depending from each other. 10.For this Variant b, you can introduce a compensation to LINE 8-7.

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Fig. 1.64 Realize modifications for Variant b

11.Activate “Variant additional” 12.Draw a new line from node FIVE to SEVEN and enter its data.

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Fig. 1.65 Introduce a new line for “Variant additional”

Create and assign a Topology Data File Topology data, such as the state of logical switches in the whole network, may be saved to a Topology Data File. To define different topology cases of a network, several variants could be defined with exactly the same characteristics but with a different topology data file. In the following we'll create such a topology data file by saving a modification of the state of a few logical switches in our example network.

1. Activate “Variant replacement” 2. Change the topology. In this case you may open the logical switches of a

transformer. 3. Save the topology with "File - Export - Topology Data", using the name

Topology1.

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Fig. 1.66 Create a topology file

4. Deactivate and activate again the “Variant replacement” but don't save it, because the topology modifications shouldn't be saved directly to the variant, but only in the topology file. Now the logical switches are closed again.

5. We now want to assign the topology file to the “Variant replacement”. Make a right-mouse-button click on the symbol of “Variant replacement” to call the popup menu, where you choose Properties. The same is possible by double-clicking the symbol of “Variant replacement”.

Tutorial


4

5

Fig. 1.67 Call the Properties dialog of the variant

6. The Variant Properties dialog appeared. 7. Press the respective button for choosing a "Topology Data File". 8. Look for the topology file and select it. 9. Open the topology file. 10.Press the OK button to finalize.

Tutorial


7

6

8 9

10

Fig. 1.68 Assign the topology file to “Variant replacement”

Create and assign a Load Data File Data, such as the power to be consumed by a load or the power to be produced by a generator, may be saved to a Load Data File. To define different loading cases of a network, several variants could be defined with exactly the same characteristics but with a different load data file. In the following we'll create such a load data file by saving a modification of the operational active power of a generator.

1. By double-clicking the generator, call its data input dialog. 2. Change the operational data of the generator and save this modification to

a "Load Data File” with "File – Export – Load Data".

Tutorial


1

2

Fig. 1.69 Change Load data

3. Call the Variant Properties dialog by double clicking the symbol of “Variant replacement”.

4. Look for the Load Data File. 5. Open the Load Data File. 6. Finalize by pressing the OK button.

Tutorial


3

4

5

5 6

Fig. 1.70 Assign the load data file to “Variant replacement” You mustn't save the “Variant replacement” after these modifications, but you need to save the project. So the best way to do is, to first deactivate the variant without saving it and then you may save the project. In general be careful that you don't save the variant, when you changed Load or Topology data, which only should be contained in the Load and the Topology Data File. Now the Variant 1 includes a Load Data File and a Topology Data File. When the variant is opened, also these two data files are loaded. In the same manner you may assign the same or other Load and Topology Data File to the other variants.

Tutorial


Load Flow Calculation

In this chapter you will learn how to perform a load flow calculation on a small network and how to get the desired results. Open the project

1. Load the Load Flow example network. 2. Call the Load Flow Parameter dialog.

2

1

Fig. 1.71 Adjustment of Load Flow calculation parameters Adjust the calculation parameters

3. Select the calculation method. 4. You may change the maximum number of iterations. Default are 20

iterations. 5. Define if the on-load tapchanging transformers shall be regulated

automatically during the load flow calculation. 6. You may choose a result-file *.rlf, which can be opened with a text editor or

Excel. 7. Use the Reference tab to edit the reference loading for elements and the

reference minimum and maximum voltage. 8. If you want to work with Area/Zone Control, use the respective tab to define

the transactions. 9. Press the OK button to save the change and to quite the Parameter dialog.

Tutorial


3

4

5

6

8

7

9

Fig. 1.72 Load Flow Parameters Choose the result variables

10.For the results showed in the single line diagram, you can choose the variables to be displayed. This can be done now or after the calculation. Open the Diagram Properties dialog.

11.Choose the Load Flow tab. 12.Select the variables to be displayed in the single line diagram for nodes and

elements. This selection doesn’t have any influence on the result tables. The result tables will contain all variables.

13.Define the units and number of digits for the result variables and decide if you want to see only the load flow results or at the same time the results of the last short circuit calculation.

Tutorial


10

11

12

12

13

13

Fig. 1.73 Result variables Perform the calculation

14.You may now perform the load flow calculation

14

Fig. 1.74 Load Flow Calculation Analyse the results in the single line diagram

Tutorial


15.The results can be analyzed directly in the single-line diagram. If additional variables should be displayed, proceed as mentioned in step 10. It’s not necessary to repeat the calculation.

16.Use the zoom buttons to get a better view of the result boxes. 17.The network elements and nodes may be colored depending on the results.

In this example the node became red because the voltage is below the minimum reference.

15

16

17

Fig. 1.75 Analyzing the results

18.Use the Diagram Properties dialog (Edit – Diagram Properties) to define the coloration of the network depending on the network characteristics or the calculation results (tab Colors and Color Ranges).

Tutorial


1818

Fig. 1.76 Coloration of the network Analyse the results using the result tables

19.Choose “Show Results” to get the results presented in tables. 20.You may get tables for a summary, the nodes, the elements or all results. 21.There is still the possibility to export the results in a file if this option was not

activated in the “Load Flow – Parameters” dialog.

Tutorial


19

20

21

Fig. 1.77 Result Tables Analyze specific results

22.If you wish to display only the results of specific elements and nodes either in the single line diagram or in the result tables, you may use the “Select Results” option to select these elements.

Tutorial


22

22

22

Fig. 1.78 Result output only for certain elements and nodes

23.To make sure that the results will be displayed in the single line diagram accordingly to this selection table, you need to activate this option in the “Edit – Diagram Properties – Load Flow” tab.

24.To make sure that the results will be displayed in the result tables accordingly to this selection table, you need to activate this option in the “Analysis – Load Flow – Show Results” dialog.

Tutorial


24

23

23

23

24

Fig. 1.79 Result output for all elements and nodes or according to list

Tutorial


Short Circuit Calculation

In this chapter you will learn how to perform a short circuit calculation on a small network and how to get the desired results. Open the project

1. Load the Short Circuit example network. 2. Call the Short Circuit Parameter dialog.

2

1

Fig. 1.80 Adjustment of Short Circuit calculation parameters Adjust the calculation parameters

3. Select the fault type. 4. Choose the calculation method. 5. Enter a fault distance if you want to display the results as well of neighbor

nodes of the fault location. 6. Possibly you need to adapt the calculation method depending parameters,

according to your needs. 7. You may choose a result-file *.rsc, which can be opened with a text editor

or Excel. 8. Define the reference for maximum loading of elements.

Tutorial


3 4

5 6

7

8

Fig. 1.81 Short Circuit Parameters Select the faulted nodes

9. Select the “Faulted nodes” tab in the Short Circuit Parameters. 10.Select the nodes which should be faulted und move them to the other table

with the arrow button.

Tutorial


9

10 10

Fig. 1.82 Select faulted nodes Select faulted lines

11.Select the “Faulted lines” tab in the Short Circuit Parameters. 12.Select the lines which should be faulted und move them to the other table

with the arrow button. 13.Insert the distance where the fault takes place, in % from the “From node”.

Tutorial


12

11

12

13

Fig. 1.83 Select faulted lines Define special faults

14.Select the “Special fault” tab in the Short Circuit Parameters. 15.Insert new fault descriptions. 16.Define the node numbers and their phases, between which the fault takes

place. 17.Assign the node numbers to the faulted network nodes.

Tutorial


14

15

16

17

Fig. 1.84 Define special faults Choose the result variables

18.For the results showed in the single line diagram, you can choose the variables to be displayed. This can be done now or after the calculation. Open the Diagram Properties dialog.

19.Choose the Short Circuit tab 20.Select the variables to be displayed in the single line diagram for nodes and

elements. This selection doesn’t have an influence on the result tables. The result tables will contain all variables.

21.Define the units and number of digits for the result variables and decide if you want to see only the short circuit results or at the same time the results of the last load flow calculation.

Tutorial


18

19

20

20

21

21

Fig. 1.85 Result variables Perform the calculation

22.You may now perform the short circuit calculation

22

Fig. 1.86 Short Circuit Calculation Analyse the results in the single line diagram

Tutorial


23.The results can be analyzed directly in the single-line diagram. If additional variables should be displayed, proceed as mentioned in step 18. It’s not necessary to repeat the calculation.

24.Use the zoom buttons to get a better view of the result boxes.

23

24

Fig. 1.87 Analyzing the results Analyse the results using the result tables

25.Choose “Show Results” to get the results presented in tables. 26.You may get tables for all fault currents, only the currents at fault locations

or the node voltages. 27.There is still the possibility to export the results in a file if this option was not

activated in the “Short Circuit – Parameters” dialog.

Tutorial


25

26

27

Fig. 1.88 Result Tables

Tutorial


Transient Stability Analysis

In this chapter you will learn how to perform a simulation with the Transient Stability module on a small network and how to get the desired results. Open the project

1. Load the Transient Stability example network.

1

1

Fig. 1.89 Open the project Enter Dynamic Data

2. Enter the Dynamic Data of the synchronous machines in the data input dialog.

Tutorial


2

2

Fig. 1.90 Dynamic data of synchronous machine

3. Enter the saturation data of the synchronous machines.

Tutorial


3

3

Fig. 1.91 Saturation data of synchronous machine Enter control circuits CCT’s

4. Click on the CCT-button 5. Click in the diagram near of a synchronous machine to past the CCT. 6. A CCT dialog appears. Enter a name for this CCT. 7. Press the OK button.

Tutorial


4

5 6

7

Fig. 1.92 Enter a CCT

8. A new diagram for the design of the CCT appeared.

Tutorial


8

8

Fig. 1.93 Diagram for the design of the CCT Design the block diagram for an AVR

9. Switch the Insert menu to a Function Block Menu.

9

Fig. 1.94 Use of the Function Block Menu

10. Choose an Input-Block. 11. Make a mouse click in the diagram, where you wish to place the block.

Tutorial


12. A properties dialog of the entered block appears. Enter the name of the block.

13. Select the variable. In this case, for an AVR, we choose the bus voltage magnitude.

14. Press the button and choose the respective node (BUS 1) from a list. 15. Close the window, pressing OK.

10

11

12

13

14

15

Fig. 1.95 Enter function blocks

16.The Input Block has been pasted in the diagram.

Tutorial


16

Fig. 1.96 An Input block has been entered

17.Choose a Sum-block. 18.Click in the diagram. The properties-dialog appears. 19.Enter a name. 20.Enter the constants and close the window with OK.

17

18

19

20

Fig. 1.97 Enter a Sum block

21.Choose a Source-block for the reference voltage.

Tutorial


22.Place it in the diagram. 23.Enter the name and the source constant.

21

22

23

Fig. 1.98 Enter a Source block

24.Select the Source-block and turn it with the rotate buttons. 25.Use the link to interconnect the function blocks.

24

24 25

25

Fig. 1.99 Interconnection of the function blocks with a link

Tutorial


26.Build the rest of the control circuit in the same manner. 27.Build control circuits for other generators. Function blocks and control

circuits may be copied from one diagram to the other.

2627

Fig. 1.100 Complete the control circuit (CCT) Adjust the calculation parameters

1. Choose the parameter menu for transient stability.

Tutorial


1

Fig. 1.101 Choose the parameter menu

2. Enter the simulation time. 3. You may choose a synchronous machine as reference for the rotor angle. 4. You have the possibility to change the step length and iteration data, but try

first with the default values.

2

4

3

Tutorial


Fig. 1.102 Adjust the simulation parameters

5. Use the Disturbances tab to define the disturbances during the transient sequence.

6. The disturbance with the sign ! is active for the following simulation. 7. You may edit the disturbance by double click or with the respective button.

5

6 7

7 6

Fig. 1.103 Select a disturbance Enter the disturbance data

8. In this case we want to add an initial load of 10% to a static load. 9. Pick the element to which the disturbance should be applied and the time,

when the disturbance has to occur. 10.Use the respective buttons to add, remove or update the disturbance

entries.

Tutorial


8

8 9

9

8

10

10

Fig. 1.104 Define disturbances Define the Screen Plots

11.Use the Screen Plots tab to define the variables, which shall be displayed on the screen or saved to a file.

12.The variables with a chart symbol will be displayed as screen plots during the simulation.

13.The variables with a disk symbol will be saved to a file and may be used to draw charts after the simulation.

14.Press Edit to edit a screen plot entry.

Tutorial


13

12

11

13 12 14

Fig. 1.105 Screen Plots to display on the screen or to save to a file

15.Define the element and the variable for which you want to draw a screen plot or a chart.

16.Use the respective buttons to add, remove or update the screen plot entries.

Tutorial


15

16

16

Fig. 1.106 Define Screen Plots Simulation and Analysis

1. Run a Transient Stability simulation.

1

Fig. 1.107 Run a Transient Stability simulation

2. A Screen Plot appears and the curves of the selected variables are being drawn. Below the diagrams, a event report is displayed.

Tutorial


2

2

Fig. 1.108 Screen plot at the end of the simulation

3. The Screen Plot shows you the selected variables during the whole simulation process. The user has the possibility to break, to continue or even to exit the simulation process.

3

Fig. 1.109 Options to break, continue or exit the simulation

Tutorial


4. Close the Screen Plot and choose Graphical Results for Transient Stability. If there were never defined any charts for this project, one empty chart will appear.

4

Fig. 1.110 Call the Graphical Results

5. You can define several charts. Every chart represents a graphical sheet and may consist of one or more subcharts. To start, add a subchart in your existing chart.

6. In the appearing dialog, enter a name for the curve and select the values for the X-Axis and Y-Axis.

7. Press the OK-button to get to the next dialog.

Tutorial


5

6

7

Fig. 1.111 Select the variables for a curve

8. Enter a name for the chart. 9. Select the curve's drawing settings. 10.If there are more than one curve entries, the displayed drawing settings are

only valid for the marked curve. 11.To add curves in the same subchart or to edit or delete existing curves, use

the corresponding buttons. 12.Switch to the Subchart Settings tab.

Tutorial


8

9

10

11

12

Fig. 1.112 Define all the curves to be displayed in one subchart

13.Select an axis. 14.Adjust the properties for the selected axis. 15.You have the possibility to show a legend in the subchart. 16.Press OK to finalize.

Tutorial


13

14

16

15

Fig. 1.113 Adjust the subchart settings

17.The defined curves are drawn in the subchart.

Tutorial


17

Fig. 1.114 A chart with one subchart and one curve

18.Define as many charts, subcharts and curves as you wish. They need to be defined only once for the project. After each simulation the same curves will be drawn in the graphical results. Remember that only variables, which have been declared as variables to be saved to a file, in the "Transient Stability – Parameter - Screen Plot" menu, are available for presentation in these charts.

Tutorial


18

Fig. 1.115 Define several charts and subcharts

19.To see the Transient Stability results listed in a table choose Result Table(Elements).

19

Fig. 1.116 Have a look at the presentation of the results in the Result Table

20.Look at the results in the Result table.

Tutorial


20

Fig. 1.117 Transient Stability results listed in a table

Tutorial


Interfaces to NEPLAN

NEPLAN has several interfaces to external applications: • Import/Export through ASCII file • Export to data base • Result data base • Clipboard • DXF-files • Raster-Graphics (e.g. BMP, PCX, TIFF, etc.) • DVG-Format (Format der Deutschen Verbundgesellschaft)

Import/Export There are two import/export files for external programs, such as MS-Excel, the EDT- and the NDT-file. The EDT-file contains topological and electrical data of the elements, the NDT-file contains the topological and loading data of the nodes. The file structure of the import/export files is given in the appendix (see "Appendix"). If data is imported without graphic, then it is possible to generate the graphic of the network automatically by the NEPLAN "Auto-Layout" function.

Topology/Loading-data files The topology and the loading data of a network may be saved in the ZDB-file (topology) and in the NDB-file (loading). The ZDB- and the NDB-file are used to define variants. To each variant a Load Data File and a Topology Data File can be assigned (see "Edit – Variant Properties" in the chapter "Menu Options").

Clipboard The diagram can be exported onto the clipboard. The clipboard data can be imported by an external program, such as a word processing program.

DXF-Files DXF-files can be imported. All diagrams are identified and displayed. The user can select the diagrams to be imported from a list. The imported drawing can be additionally scaled. The imported diagrams are managed by the program in different graphic layers. The imported drawing can be changed.

Tutorial


Cadastre and Raster-Graphics Files (BMP, PCX, TIFF) Raster graphics files (BMP, PCX, TIFF, etc.) can be imported in any diagram. It is possible to import a raster graphic (e.g. PCX) as a cadastre. The cadastre can be used as background for the NEPLAN network data. The cadastre can be calibrated to use real world coordinates.

Tutorial


Tips from the Practice

Important tips from the practice are given here.

Asymmetrical Network Structure

Representation of an Asymmetrical Line It is recommended to enter lines in a compact way. A 3-phase line from node A to B can theoretically be entered as three single phase lines, which are coupled between each other. In this way the program will work not only with the current circuit resp. the series impedance matrices but also with the coupling matrices. This increases the calculation effort. The better way is to represent the 3-phase line with one 3-phase line. The same is valid for a 2-phase line.

Load Flow

Divergence using PV-Nodes

• When using PV-nodes the Newton-Raphson method should be used. The user has to take care that no disconnect or load switches as well as short lines will be connected to the PV-node, because of numerical problems. If disconnect and load switches are connected to PV-nodes it is advisable to reduce them during calculation. If for example a generator is connected to a bus bar through disconnect switches (one open, one closed), the generator node should be marked as reducible (see "Node Data Input" in chapter "Element Data Input and Models").

• When using the current iteration method the same is valid. The convergence can be additionally influenced by the accelerating factor (see "Calculation Parameters (LF)" in chapter "Load Flow"). Probably the value must be reduced until 0.05 to obtain convergence. The convergence criteria should also be reduced.

Switching Topology or Connecting Motors

Tutorial


• If the motor starting module is not available and the user like to make voltage drop calculation when switching the topology or connecting motors, the network impedance (network feeder) must be represented by a line. In the normal load flow calculation the internal network impedance (Sk", Un) is not considered.

Element Data Input and Models



Data Input Dialogs of Network Elements

The element data for the power system calculation are entered with the help of data input dialogs. The dialog appears after having entered the element graphi-cally. The entered data will be saved into a common database (project file), which will be used from all calculation modules. The modules read only the data, which is necessary to perform the specific calculation. The data not used will be over read. At the bottom of the data input dialog the following push buttons are available:

Copy and Paste

Copies the data from an element into an internal buffer. While inserting the data for another element, it is possible to get these data from the buffer with the option "Paste". The data are transferred to the data input dialog of this element.

Library For some elements it is possible to select a library containing predefined standard data. This library can be built up in the menu Libraries.

Export Its possible to export the data of the element to the actual library by pressing the Export button. A type name has to be entered before or a type has to be chosen in the type option of the Params tab.

OK The edited data will be saved. A new element will be inserted. Cancel The edited data will not be changed. A new element will not be

inserted. Help The online Help will be called. Tools Its possible to use background colors for the data fields of the

data input dialog, depending on if the respective data is necessary for a certain calculation. A different color may be chosen for mandatory fields and preference fields.

Classification of Data in the Data Input Dialog



In the following sections the parameters to be entered in the Data Input Dialogs will be described. For every parameter there is an indication for what kind of calculation the input is needed. The indication is given by:

L Load flow, Optimal Power flow, Contingency Analysis, Voltage Stability

S Short circuit, Distance protection M Motor starting H Harmonic frequency analysis P Distance protection analysis D Dynamic Analysis, Small Signal Stability R Reliability O Selectivity Analysis

If there is a parentheses (), it means, that this parameter is used for all NEPLAN-modules. All parameters used for short circuit analysis are necessary also for selectivity analysis, because the short circuit simulation makes part of the selectivity analysis.

Element - Info Every element has an Info tab, which gives general information about the element. The type of information is nearly the same from one element to the other, thats why this tab is explained here and wont be mentioned anymore in the elements data input chapters.

Name Name of element. When the Input dialog of an element or node is open for the first time after the entry of this element, there is a ""-button beside the name field. If you want to represent an already existing element in the project again, then press this button and choose the respective element.

ID () ID-number of element (generated by NEPLAN). Partial Network ID

() ID-number of the partial network (generated by NEPLAN).

Description Description of element. Area () Indicates the area to which the element belongs. New



areas may be defined in "Edit Variant Properties". Zone () Indicates the zone to which the element belongs. New

zones may be defined in "Edit Variant Properties". Projected Indicates, if the line is projected or if it exists already. Connected nodes

() From: Name of starting node. To: Name of ending node. Checkbox ON/OFF: Connects or disconnects the element at the respective node.

For some elements the user has the possibility to choose the phases, so its possible to define an asymmetrical element. This is done by the following option:

Phases () Indicates the phasing of the element. Possible values are: - L1L2L3N: Symmetrical element - L1N: Single phase element, phase L1 - L2N: Single phase element, phase L2 - L3N: Single phase element, phase L3

If an element doesnt include this option, there exists an other similar element for asymmetrical applications, which has to be entered (e.g. asymmetrical line).

Element - Reliability Every element has a Reliability tab for the data input used in Reliability Analysis. This module is still in development, therefore these parameters will be explained later.

Element - User Data Every element has a User Data tab. The user may define his own variables, which enter in a table list. The values of the variables may be modified directly in the table list. If the checkbox of a variable is checked, the variable will be displayed in the single line diagram. The variables are only for information and documentation purposes and do not enter in any calculations.

New Variable: Name

Name of variable to enter in the table list.



New Variable: Type

Type of variable to enter in the table list.

Add Variable

Press this button to add a variable to the table list.

Remove Variable

Press this button to remove a variable from the table list.

Element - More…

Frequency dependence In general the resistances and the inductances in the equivalent circuits of the network elements are frequency-dependent. The program permits to consider the frequency dependency in three different manners:

• according to an exponential function • according to a table R(f) and L(f) • according to a locus diagram

Frequency Dependency According to an Exponential Function The frequency dependency of a resistance resp. of an inductance is according to the following formulas:

−⋅+⋅=Br

fnfArRn)f(R 11

Bl

fnfAlLn)f(L

⋅⋅=

It means: R(f), L(f): resistance resp. inductance at frequency f Rn, Ln: nominal value of the resistance resp. inductance at nominal

system frequency Ar, Br, Al, Bl: Factors f: Frequency Fn: nominal system frequency



The figures 4.1 and 4.2 show the characteristic of R(f) resp. L(f) according to the above formulas. This frequency dependency is only defined for frequencies above the nominal system frequency.

0.0 500.0 1000.0

frequency f [Hz]

0.0

10.0

20.0

R(f)/Rn

Fig. 4.1 Frequency dependency of a resistance

0.0 500.0 1000.0

frequency f [Hz]

0.0

0.5

1.0

L(f)/Ln

Fig. 4.2 Frequency dependency of an inductance

Frequency Dependency According to a Table R(f) and L(f) It is possible to enter the frequency dependency of R and L tabulated. It is meaningful to give the values for the k-th harmonic fk as based values R(fk)/Rn and L(fk)/Ln. The base are the values Rn, Ln for nominal system frequency fn. A pair of values fk and R(fk)/Rn resp. fk and L(fk)/Ln are



designated as a foothold. For frequencies not corresponding with the frequencies of a foothold a linear interpolation will be done.

Frequency Dependency According to a Locus Diagram Arbitrary impedance curves can be represented by a locus diagram. It is possible to reproduce given impedance curves (e.g. results of a measurement). For all frequencies fk the real value R(fk) and the imaginary value X(fk) of the impedance Z(fk) can be entered tabulated (R and X in series). These value groups (fk, R, X) are designated as footholds of the locus diagram. For frequencies not corresponding with the frequencies of a foothold, a linear interpolation will be done (separate for the real and the imaginary value). This kind of frequency dependency is only valid for the network elements "network feeder", shunts and loads. The elements of the equivalent circuits will be calculated exclusively by the values of the locus diagram and not by the formulas given for the element models.

Investment Analysis



Station

This chapter describes the parameters of the Data Input Dialog of a station. This element is not needed for calculations.

Station - Parameters

Name Station name. Type Station type Municipality Municipality, where the station has been built. Location Location of the station. Protection R Protection concept in the station

This element is not needed for calculations. It is used to switch between different network layers.

Station-Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Station-Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Station-User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

Station-More… Frequency dependence… By pressing this button of the More tab, the Frequency dependence input parameters can be entered. They are only used for harmonic analysis. The



description can be found in Frequency dependence of chapter Data Input Dialogs of Network Elements-Element - More on page 4-4. Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6.



Node

This chapter describes the parameters of the Data Input Dialog of a node.

Node-Parameters

Name Node name. Area () Defines the area to which the element belongs. Zone () Defines the zone to which the element belongs. Node type () Node type. Following values are possible:

- Bus bar - Sleeve - Special node - Main bus bar The thickness of a node in the diagram can be changed according to the here entered value (see menu option "Line Width" in chapter "Menu Options"). Otherwise the input value has no importance.

Dist. protection node

P Indicates, if the node has to be considered, when making the automatic relay setting. If this option is checked, the node will be handled like a distance protection relay node.

Un () Nominal system voltage of node in kV. Uset LDR Setting value in % of nominal voltage for this node.

Input is only relevant, if the node will be regulated during calculation with a tap-changing transformer (see chapter "Load Flow").

Umin LDR Min. allowable node voltage in %. If the voltage will go below this limit during calculation, this value will be kept (only for Newton-Raphson method).

Umax LDR Max. allowable node voltage in %. If the voltage will go beyond this limit during calculation, this value will be kept (only for Newton-Raphson method).

f SP Frequency Ipmax SP Max. allowable peak short circuit current of bus-bar in

kA. t dp P Tripping time in seconds of a primary protection, e.g.

fuse in a distribution pole.



Node-Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Node-Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Node-User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

Node-More… Frequency dependence… By pressing this button of the More tab, the Frequency dependence input parameters can be entered. They are only used for harmonic analysis. The description can be found in Frequency dependence of chapter Data Input Dialogs of Network Elements-Element - More on page 4-4. Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6.



DC Node

This chapter describes the parameters of the Data Input Dialog of a node.

DC Node-Parameters

Name Node name. Area () Defines the area to which the element belongs. Zone () Defines the zone to which the element belongs. Un () Nominal system voltage of node in kV.

DC Node-Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

DC Node-Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

DC Node-User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

DC Node-More… Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6.



Line

This chapter describes the parameters of the Data Input Dialog of a line and the corresponding line model.

Line-Parameters

Name Name of element. Type Applicable only with a line library. Pressing the button

"", the type may be chosen and the data can be transferred from the predefined library.

Length () Length of the line in km or miles or 1000 feet (see Units).

Units () Units for the input values below. Possible values are: - Ohm/km: Ohm, µS, µF per km - Ohm/miles: Ohm, µS, µF per miles - Ohm/1000ft: Ohm, µS, µF per 1000 feet

R(1) () Positive sequence resistance in Ohm/km or see Units. R(0) SP Zero sequence resistance in Ohm/km or see Units. X(1) () Positive sequence reactance in Ohm/km or see Units. X(0) SP Zero sequence reactance in Ohm/km or see Units. C(1) () Positive sequence capacitance in µF/km or see Units. C(0) SP Zero sequence capacitance in µF/km or see Units. G(1) () Positive sequence conductance in µS/km or see Units. Ir max L Maximum rated current in A. The loading of the line can

be calculated according to Ir min or Ir max (see load flow calculation parameters).

Ir min L Minimal rated current in A. The loading of the line can be calculated according to Ir min or Ir max (see load flow calculation parameters).

T perm SP Max. permitted temperature in °C for the calculation of minimum short circuit currents. The default value is 80 °C.

Red. factor L Reduction factor. Ir will be corrected to: Ir min = red.fact. * Ir min; Ir max = red.fact. * Ir max

No. of lines () Number of parallel lines between starting and ending node.

Q Cross-section of the line in mm2 . A line can be



displayed with different line width according to the cross section (see menu option "Line Width" in chapter "Menu Options").

Cable Indicates, whether the line is a cable or not. The cables and the overhead lines can be displayed with different line types (see menu option "Edit Diagram Properties -Lines").

Overhead Indicates, whether the line is overhead or not. The overhead lines and the cables can be displayed with different line types (see menu option "Edit Diagram Properties -Lines").

Switchable L Indicates, if the line is switchable for calculation of optimal separation point.

Line-Sections This option is useful if the line consists of sections. In the Sections tab the line sections can be entered. With the corresponding push buttons the sections can be inserted, updated or deleted. The parameters of the sections can also be taken from a line library. In the table of the line section entries, the user can see all entered line sections. The input fields for the parameters are the same as in the Line-Params tab. The length and parameters of the whole line are calculated automatically with the entered line sections and they appear in the Params tab. These calculated parameters cannot be modified, because they represent a combination of the line sections parameters.

Line-Pylons The user has the possibility to calculate the parameters of an overhead line with the help of the Pylons tab in the line data input dialog. With this function, the parameters of one single line will be calculated by inserting the conductors characteristics and the arrangement data. To be able to enter the arrangement data, its necessary to choose one or more pylons. The respective pylons have to be entered before graphically from the Symbol Window (see chapter Pylon on page 4-33). If there are coupled lines, it is recommended to use the line-coupling editor, which calculates the coupling impedances and the parameters of all the considered lines (see chapter Line-Coupling on page 4-28). Phase conductors Conductors per Bundle conductors can also be entered and calculated. The



bundle number of the conductor elements can be specified here. The values are 1..4.

Distance Distance of the conductor elements in cm. Typical value: 40 cm.

Diameter Diameter of a conductor element in cm. R Specific resistance in Ω/km of the phase conductors at 20°

Celsius. Sag Sag h of the conductors in m. For the parameter calculation

the y-values are corrected as follows: ynew = yinp - 0.7·h.

Pylon data Insert A pylon, entered before, may be selected from a list. Its

possible to choose various pylons and for everyone, the arrangement data has to be entered.

Delete A pylon may be removed from the list. The respective arrangement data will get lost.

x (L1) x-coordinate in m of phase conductor L1 related to the pylon (see remark below).

y (L1) y-coordinate in m of phase conductor L1 from earth. x (L2) x-coordinate in m of phase conductor L2 related to the

pylon. y (L2) y-coordinate in m of phase conductor L2 from earth. x (L3) x-coordinate in m of phase conductor L3 related to the

pylon. y (L3) y-coordinate in m of phase conductor L3 from earth. Circuit data calculation Twisted Indicates, if the phase conductors of the overhead line are

twisted or not. The symmetrical ß-twisting will be assumed (cyclical transposition of the phase conductors at 1/3 and 2/3 of the line). The input is valid for each line (phase system).

rho E Earth resistivity in Ωm. Typical values are: Rock: greater 3000 Ωm; Stone floor, Slate: 1000..3000 Ωm; gneiss, granite: 10000 Ωm; dry sand, gravel: 200..1200 Ωm; wed sand, chalky soil: 70..200 Ωm; field: 50..100 Ωm; clay, loam: 100..50 Ωm; marshy soil, alluvial land: smaller 20 Ωm. Default value: 100 Ωm.

Calculate The line parameters will be calculated based on the data



entered in the Pylons tab. The result will be indicated in the Params tab.

Earth conductor Active Defines, whether an earth conductor exists or not. If it is

active, it will be considered for the calculation. R Specific resistance in Ω/km of the earth conductor at 20°

Celsius. Diameter Diameter of the earth conductor in cm. Permeability Relative permeability µ of the earth conductor. Typical

values are: copper, aluminium conductors: µ=1.0; aluminium/steel conductors with one layer aluminium: µ~5..10; aluminium/steel conductors with cross section ratio greater equal 6: µ~1.0; steel conductors: µ=25.0 .

X x-coordinate in m of the earth conductor related to the pylon (see remark below).

Y y-coordinate of the earth conductor in m from earth. If a phase does not exist its input data remains zero.

Remark to the Coordinate Input:

Earth conductors

Phase conductors

Y axis

X axis

0 Fig. 4.1 Pylon arrangement

Earth or phase conductors, which are left of the pylon, must be entered with negative x-coordinate. Conductors, which are right of the pylon, must be entered with positive x-coordinate.



Line-Compensation

Name Name of element For the primary and the secondary side of the line, the following parameters have to be introduced, if there is a line compensation:

P(1) () Active power of positive sequence Q(1) () Reactive power of positive sequence P(0) SP Active power of zero sequence Q(0) SP Reactive power of zero sequence Active () The user can define, which portion in % of the

compensation is active.

Line-Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Line-Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Line-User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

Line-More… Frequency dependence… By pressing this button of the More tab, the Frequency dependence input parameters can be entered. They are only used for harmonic analysis. The description can be found in Frequency dependence of chapter Data Input Dialogs of Network Elements-Element - More on page 4-4.



Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6. Line Loads… For the description of the parameters for Line Loads see chapter Line Load on page 4-146.

Recommended Values for Line Zero Sequence Data: The zero sequence data of a line are dependent on the line type (cable or overhead line), of its structure and of its laying (cable). In reference / 3 / recommended values are shown.

Description of the Model (Line) R X

Ycomp2 B11 G22

B22 G11

Ycomp1

Y11 Y22

Fig. 4.2 Model of a line The model parameters of the positive and zero sequence are calculated as fol-lows: Positive sequence Zero sequence R = R(1) · length R = R(0) · length X = X(1) · length X = X(0) · length B = 2·PI·f·C(1) · length B = 2·PI·f·C(0) · length G11 = G / 2 G11 = 0.0



B11 = B / 2 B11 = B / 2 G22 = G / 2 G22 = 0.0 B22 = B / 2 B22 = B / 2 Ycomp1 = G1s + jB1s Ycomp1 = G1s + jB1s Ycomp2 = G2s + jB2s Ycomp2 = G2s + jB2s Y11 = G11 + j·B11 + Ycomp1 Y11 = G11 + j·B11 + Ycomp1 Y22 = G22 + j·B22 + Ycomp2 Y22 = G22 + j·B22 + Ycomp2 If the input values P1(1,0), Q1(1,0), P2(1,0), Q2(1,0) unequal zero, it is:

G1s = (P1*P1 + Q1*Q1) / (P1*Un²) G1s = (P1*P1 + Q1*Q1) / (P1*Un²) B1s = (P1*P1 + Q1*Q1) / (Q1*Un²) B1s = (P1*P1 + Q1*Q1) / (Q1*Un²) G2s = (P2*P2 + Q2*Q2) / (P2*Un²) G2s = (P2*P2 + Q2*Q2) / (P2*Un²) B2s = (P2*P2 + Q2*Q2) / (Q2*Un²) B2s = (P2*P2 + Q2*Q2) / (Q2*Un²) Further it is:

L = X / (2·PI·f) R_T = R[1+0.0039·(T-20)] R_T = R[1+0.0039·(T-20)]

Meaning: f System frequency T Max. permitted temperature R_T Reactance at temperature T Ycomp1 Admittance of the line compensation on side 1 Ycomp2 Admittance of the line compensation on side 2

In case the minimum short circuit current is calculated R_T will be taken instead of R (by 20° C). Remark: C(1) res. Y(1) are not used in a short circuit calculation according to IEC.

Model for Harmonic Analysis A distributed parameter line model is used for modeling the line. The series and shunt elements are calculated from the exact line equation for each frequency. Only the positive sequence is considered. The series impedance Z12 between the nodes 1 and 2 of the line is calculated as:



Z Z f g fW12 = ⋅( ) sinh( ( ))

The shunt impedances are:

Z f Z f Z f g fW1 2 2( ) ( ) ( ) coth( ( ) / )= = ⋅

The values are for the equation: U Z I= ⋅ ZW means the natural impedance and g means the propagation constant of the line. Neglecting the resistant to earth, the following formulas are valid for ZW and g:

11

11

2)(2)(

)(CfjG

fLfjfRfZW ⋅⋅⋅⋅+⋅⋅⋅⋅+

=ππ

lCfjGfLfjfRfg ⋅⋅⋅⋅⋅+⋅⋅⋅⋅⋅+= )2())(2)(()( 1111 ππ

It means: F arbitrary frequency L1(f) frequency dependent inductance of line in Henry/km R1(f) frequency dependent resistance of line in Ohm/km C1 frequency independent capacitance of line in µF/km G1 frequency independent conductance of line in µS/km L length of line in km.

If the frequency dependency of X1 and/or R1 are given, the values L1(f) and/or R1(f) are calculated from X1 and R1.



Asymmetrical Line

This chapter describes the parameters of the Data Input Dialog of an asymmetrical line and the corresponding model.

Asymmetrical Line - Parameters





Phase values for R

() Phase values for resistance R in Ohm/km or see Units.

Phase values for X

() Phase values for reactance X in Ohm/km or see Units.

Phase values for C

() Phase values for capacitance C in µF/km or see Units.

Ir max L Maximum rated current in A. The loading of the line can be calculated according to Ir min or Ir max (see load flow calculation parameters).


T perm SP Max. permitted temperature in °C for the calculation of minimum short circuit currents. The default value is 80 °C.

Red. factor L Reduction factor. Ir will be corrected to: Ir min = red.fact. * Ir min; Ir max = red.fact. * Ir max

No. of lines () Number of parallel lines between starting and ending node.

Q Cross-section of the line in mm2 . A line can be displayed with different line width according to the cross



section (see menu option "Line Width" in chapter "Menu Options").

Cable Indicates, whether the line is a cable or not. The cables and the overhead lines can be displayed with different line types (see menu option "Edit Diagram Properties -Lines").

Overhead Indicates, whether the line is overhead or not. The overhead lines and the cables can be displayed with different line types (see menu option "Edit Diagram Properties -Lines").

Switchable L Indicates, if the line is switchable for calculation of optimal separation point.

Asymmetrical Line - Pylons The user has the possibility to calculate the parameters of an overhead line with the help of the Pylons tab in the line data input dialog. With this function, the parameters of one single line will be calculated by inserting the conductors characteristics and the arrangement data. To be able to enter the arrangement data, its necessary to choose one or more pylons. The respective pylons have to be entered before graphically from the Symbol Window (see chapter Pylon on page 4-33). If there are coupled asymmetrical lines, it is recommended to use the asymmetrical line - coupling editor, which calculates the coupling impedances and the parameters of all the considered lines (see chapter Asymmetrical Line-Coupling on page 4-28). Phase conductors Conductors per bundle

Bundle conductors can also be entered and calculated. The number of the conductor elements can be specified here. The values are 1..4.

Distance Distance of the conductor elements in cm or inch. Typical value: 40 cm.

Diameter Diameter of a conductor element in cm or inch. R Specific resistance in Ω/km or Ω/miles or Ω/1000ft of the

phase conductors at 20° Celsius. Sag Sag h of the conductors in m or in feet. For the parameter

calculation the y-values are corrected as follows: ynew = yinp - 0.7·h.



Pylon data Insert A pylon, entered before, may be selected from a list. Its

possible to choose various pylons and for everyone, the arrangement data has to be entered.

Delete A pylon may be removed from the list. The respective arrangement data will get lost.

x (L1) x-coordinate in m or feet of phase conductor L1 related to the pylon (see remark below).

y (L1) y-coordinate in m or feet of phase conductor L1 from earth. x (L2) x-coordinate in m or feet of phase conductor L2 related to

the pylon. y (L2) y-coordinate in m or feet of phase conductor L2 from earth. x (L3) x-coordinate in m or feet of phase conductor L3 related to

the pylon. y (L3) y-coordinate in m or feet of phase conductor L3 from earth. Circuit data calculation Twisted Indicates, if the phase conductors of the overhead line are

twisted or not. The symmetrical beta-twisting will be assumed (cyclical transposition of the phase conductors at 1/3 and 2/3 of the line). The input is valid for each line (phase system).

rho E Earth resistivity in Ωm. Typical values are: Rock: greater 3000 Ωm; Stone floor, Slate: 1000..3000 Ωm; gneiss, granite: 10000 Ωm; dry sand, gravel: 200..1200 Ωm; wed sand, chalky soil: 70..200 Ωm; field: 50..100 Ωm; clay, loam: 100..50 Ωm; marshy soil, alluvial land: smaller 20 Ωm. Default value: 100 Ωm.

Calculate The line parameters will be calculated based on the data entered in the Pylons tab. The result will be indicated in the Params tab.

Earth conductor Active Defines, whether an earth conductor exists or not. If it is

active, it will be considered for the calculation. R Specific resistance in Ω/km of the earth conductor at 20°

Celsius. Diameter Diameter of the earth conductor in cm. Permeability Relative permeability µ of the earth conductor. Typical

values are: copper, aluminium conductors: µ=1.0; aluminium/steel conductors with one layer aluminium:



µ~5..10; aluminium/steel conductors with cross section ratio greater equal 6: µ~1.0; steel conductors: µ=25.0 .

X x-coordinate in m or feet of the earth conductor related to the pylon (see remark below).

Y y-coordinate in m or feet of the earth conductor from earth. If a phase does not exist its input data remains zero.

Remark to the Coordinate Input:

Earth conductors

Phase conductors

Y axis

X axis

0 Fig. 4.3 Pylon arrangement

Earth or phase conductors, which are left of the pylon, must be entered with negative x-coordinate. Conductors, which are right of the pylon, must be entered with positive x-coordinate.

Asymmetrical Line - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Asymmetrical Line - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.



Asymmetrical Line - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

Asymmetrical Line - More… Frequency dependence… By pressing this button of the More tab, the Frequency dependence input parameters can be entered. They are only used for harmonic analysis. The description can be found in Frequency dependence of chapter Data Input Dialogs of Network Elements-Element - More on page 4-4. Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6.

Description of the Model (Asymmetrical Line) Asymmetrical lines are entered in the phase system, L1, L2, L3 with or without earthing conductor. The line will be described with two symmetrical matrices as follows:

UUUU

Z Z Z ZZ Z Z ZZ Z Z ZZ Z Z Z

IIII

L

L

L

N

L L L L L L L N

L L L L L L L N

L L L L L L L N

L N L N L N N N

L

L

L

N

1

2

3

1 1 1 2 1 3 1

1 2 2 2 2 3 2

1 3 2 3 3 3 3

1 2 3

1

2

3

=

•

− − − −

− − − −

− − − −

− − − −

with Z = R + jX

IIII

Y Y Y YY Y Y YY Y Y YY Y Y Y

UUUU

L

L

L

N

L L L L L L L N

L L L L L L L N

L L L L L L L N

L N L N L N N N

L

L

L

N

1

2

3

1 1 1 2 1 3 1

1 2 2 2 2 3 2

1 3 2 3 3 3 3

1 2 3

1

2

3

=

•

− − − −

− − − −

− − − −

− − − −

Corresponding to the line phasing, elements in the matrix can be set to zero. No values for these elements should be entered in the input mask. For example, for a single phase line L1N only the elements for L1-L1, L1-N and N-N must be entered.



If there is no earthing conductor the values can be set to zero. The impedance and admittance values can be calculated from the conductor arrangement in the Pylons tab. During the network calculation the neutral conductor will be reduced: UN = 0.0. The 4x4 matrices will become two 3x3 matrices. These matrices can be trans-formed into the symmetrical component system with the help of the transformation matrix [Z012] = [T]-1[ZL1L2L3]⋅[T]:

[ ]T a aa a

=

1 1 111

2

2

with a = -0.5 + j0.5 * √3

Remark It is recommended to enter lines in a compact way. A 3-phase line from node A to B can theoretically be entered as three single phase lines, which are coupled between each other. In this way the program will work not only with the current circuit resp. the series impedance matrices but also with the coupling matrices. This increases the calculation effort. The better way is to represent the 3-phase line with one 3-phase line. The same is valid for a 2-phase line. In case of a single phase or a two phase system with a neutral conductor (cable) and omitting all currents in earth, there are two ways to enter the data: ZL

ZN

1. Addition of ZL and ZN 2. Considering the neutral ZN

•

+

=

N

L

L

L

N

L

L

L

IIIIZNZL

UUUU

3

2

1

3

2

1

000000000000000)(

or

•

−

=

N

L

L

L

N

L

L

L

IIII

ZNZN

ZNZL

UUUU

3

2

1

3

2

1

0000000000

00

The first way is the better way and corresponds to the measurement of the impedances.



DC Line

This chapter describes the parameters of the Data Input Dialog of a line and the corresponding line model.

DC Line - Parameters

Name Name of element. Type Applicable only with a DC-line library. Pressing the

button "", the type may be chosen and the data can be transferred from the predefined library.



R () Positive sequence resistance in Ohm/km or see Units. L () Inductance in mH/km. Not used for steady state

calculations. Ir max L Maximum rated current in A. The loading of the line can

be calculated according to Ir min or Ir max (see load flow calculation parameters).


DC Line - Sections Line sections are not allowed for DC lines.

DC Line - Pylons Line pylons are not considered for DC lines.



DC Line - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

DC Line - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

DC Line - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

DC Line - More… Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6.

Description of the Model (DC Line) for steady state calculation RL

Fig. 4.4 Model of a DC line

RL = R*Length



Line-Coupling

To insert line-coupling data, first the line-coupling symbol has to be chosen in the symbol window and pasted to the lines, which are coupled together. If the coupling impedances and the line data are known, they directly can be entered in the line-coupling and the line data input dialog, respectively. There exists the possibility to calculate these data by entering the information about the conductors characteristics and the conductors arrangements data in the line-coupling data input. By pressing the button "Calculate" in the Impedances tab, the results will be written into the line-parameters and the line-coupling- impedances.

Coupling group A coupling group can consist of maximum 6 lines (systems).

Name Name of coupling group Earth conductors

SP By pressing the ""-button the earth conductors of the coupling group may be chosen.

Phase conductors

SP By pressing the ""-button the phase conductors may be chosen for every system of the coupling group .

Coupling-Impedances The coupling impedances can be entered after having entered the coupled lines (systems). These data and the line parameters can also be calculated, if the arrangement data is known and entered in the Arrangement tab. For each coupling (e.g. 1-2: system 1 and system 2; 1-3: system 1 and system 3) the following data can be entered or calculated:

R(1) SP Positive sequence mutual resistance in Ω/km or Ω/mile or Ω/1000ft.

X(1) SP Positive sequence mutual reactance in Ω/km or Ω/mile or Ω/1000ft.

Y(1) SP Positive sequence mutual admittance in µS/km or µS /mile or µS /1000ft.

R(0) SP Zero sequence mutual resistance in Ω/km or Ω/mile or Ω/1000ft.



X(0) SP Zero sequence mutual reactance in Ω/km or Ω/mile or Ω/1000ft.

Y(0) SP Zero sequence mutual admittance in µS/km or µS /mile or µS /1000ft.

Length SP Length of mutual coupling lc in km or mile or 1000ft.

Calculation By pressing the button Calculation, the Coupling Impedances and the line parameters will be calculated, based on the arrangement data.

Coupling-Conductors Earth conductor (Cond.1 – Cond.3) Diameter Diameter of the earth conductor in cm. R Specific resistance in Ω/km or Ω/mile or Ω/1000ft of the

earth conductors at 20° Celsius. Sag Sag h of the conductors in m or feet. For the parameter

calculation the y-values are corrected as follows: Ynew = yinp - 0.7·h.

Phase conductors (System 1 – System 6) No. con. elem. Bundle conductors can also be entered and calculated. The

number of the conductor elements can be specified here. The values are 1..4.

Dist. con. elem. Distance of the conductor elements in cm or inch. Typical value: 40 cm.

Diameter Diameter of a conductor element in cm or inch. R Specific resistance in Ω/km or Ω/mile or Ω/1000ft of the

phase conductors at 20° Celsius. Sag Sag h of the conductors in m or feet. For the parameter

calculation the y-values are corrected as follows: Ynew = yinp - 0.7·h.

Coupling-Arrangement

General Data



Re Earth resistivity in Ωm. Typical values are: Rock: greater 3000 Ωm; Stone floor, Slate: 1000..3000 Ωm; gneiss, granite: 10000 Ωm; dry sand, gravel: 200..1200 Ωm; wed sand, chalky soil: 70..200 Ωm; field: 50..100 Ωm; clay, loam: 100..50 Ωm; marshy soil, alluvial land: smaller 20 Ωm. Default value: 100 Ωm.

Permeab. µ Relative permeability of the earth conductor. Typical values are: copper, aluminium conductors: µ=1.0; aluminium/steel conductors with one layer aluminium: µ~5..10; aluminium/steel conductors with cross section ratio greater equal 6: µ~1.0; steel conductors: µ=25.0 .

Twisted Indicates, if the phase conductors of the overhead line are twisted or not. The symmetrical ß-twisting will be assumed (cyclical transposition of the phase conductors at 1/3 and 2/3 of the line). The input is valid for each line (phase system).

Earth conductors (Cond. 1 – Cond. 3) X x-coordinate in m or feet of the earth conductor related to

the pylon. Y y-coordinate in m or feet of the earth conductor from earth. Earth cond. 13 checkbox: Defines, whether an earth conductor exists or

not. Phase conductors (System 1 – System 6) x (L1) x-coordinate in m or feet of phase conductor L1 related to



the pylon. y (L3) y-coordinate in m or feet of phase conductor L3 from earth.

If a phase does not exist its input data remains zero.



Coupling-Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Coupling-Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Coupling-User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

Description of the Model (Line Coupling) The line couplings are only considered in the short circuit calculation (IEC and superposition method), in the module Distance Protection and for asymmetrical load flow. The formula to calculate the per unit values are: Rc(1) = Rc(1) · lc / Zn rc(0) = Rc(0) · lc / Zn Xc(1) = Xc(1) · lc / Zn xc(0) = Xc(0) · lc / Zn Yc(1) = Yc(1) · lc · Zn yc(0) = Yc(0) · lc · Zn

The nominal system impedance Zn is calculated as follows.

• Coupling between systems with the same nominal system voltage Un Zn = Sn / Un².

• Coupling between systems with unequal nominal system voltage Un1, Un2 Zn = Sn / (Un1 · Un2).

Sn: base power 100 MVA (set by the program).

Asymmetrical line coupling A line coupling is asymmetrical when at least one line has asymmetrical structure. The matrix for two coupled lines are:



[ ] [ ][ ] [ ]

UUUUUU

Z ZcZc Z

IIIIII

L

L

L

L

L

L

L

L

L

L

L

L

111222

111222

1

2

3

1

2

3

11 12

12 22

1

2

3

1

2

3

=

•

The matrices Z11 and Z22 are current circuit data or series impedance data. The elements of these matrices can be entered in the dialog box for lines. The matrix Zc12 is the coupling matrix between the two 3-phase lines (systems). The elements of this matrix can be entered in the dialog box for line couplings (see above).

UUU

Zc Zc ZcZc Zc ZcZc Zc Zc

III

L

L

L

L L L L L L

L L L L L L

L L L L L L

L

L

L

111

222

1

2

3

1 1 1 2 1 3

1 2 2 2 2 3

1 3 2 3 3 3

1

2

3

=

•

− − −

− − −

− − −

The coupling impedance and admittance matrices can be calculated from the conductor arrangement. The coupling matrix can be transformed into the symmetrical component system with the help of the transformation matrix. It is possible to couple at maximum six 3-phase lines (systems). Each line (system) can have asymmetrical structure, that means any phase(s) can be omitted.



Pylon

The pylon symbol may be placed somewhere near the corresponding lines. In the data input dialog of a pylon, no parameter data may be entered. In the lines and earth conductors the pylons have to be selected and the arrangement data can be entered and modified in the Pylons tab of the line data input dialog, see Line-Pylons in chapter Line on page 4-13.

Pylon-Parameters

Name Name of element Earth Conductors

The earth conductors assigned to this pylon are shown with its arrangement data.

Lines The lines assigned to this pylon are shown with its arrangement data.

Draw A drawing shows the pylon with the arrangement of the assigned lines and earth conductors.

Pylon-Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Pylon-Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Pylon-User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Coupler

This chapter describes the parameters of the Data Input Dialog of a Coupler.

Coupler-Parameters



Ir L Rated current in kA. Ipmax S Max. allowable peak short circuit current in kA. Remote controlled

R Indicates, if the switch is remote controlled.

Bay configuration

R Configuration of the coupler: DCD: Disconnecter Circuitbreaker - Disconnecter D: Disconnecter

r(1) D Positive sequence resistance in per unit. x(1) D Positive sequence reactance in per unit. r(0) D Zero sequence resistance in per unit. x(0) D Zero sequence reactance in per unit.

Remark: The resistance and reactance for the switch model are only necessary to be introduced, when the switches are not reduced during calculation (see "Reduce" option in calculation parameters of the different calculation modules). For load flow calculations with the method "Extended Newton Rapson" these impedances are never relevant, because this LF-method is modeling the switches without impedances. For Dynamic Analysis the impedance data always have to be entered.

Coupler – Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.



Coupler-Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Coupler-User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Reactor

This chapter describes the parameters of the Data Input Dialog of a reactor and the corresponding reactor model.

Reactor-Parameters

Name Name of element. Type Applicable only with a reactor library. Pressing the


Ur () Rated voltage in kV. Ir () Rated current in A. uRr(1) () Copper losses in % of Sr=√3·Ur·Ir. ukr(1) () Short circuit voltage in % of Sr=√3·Ur·Ir.

Reactor-Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Reactor-Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Reactor-User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

Reactor-More… Frequency dependence… By pressing this button of the More tab, the Frequency dependence input parameters can be entered. They are only used for harmonic analysis. The




Description of the Model (Reactor)

R X

Fig. 4.5 Model for a reactor The model parameters of the positive and zero sequence are calculated as fol-lows: Positive and Zero Sequence Z = ukr(1)·Ur/(√3·Ir·100) R = uRr(1)·Ur/(√3·Ir·100) X = √(Z² - R²)



Transformer

This chapter describes the parameters of the Data Input Dialog of a transformer and the corresponding transformer model.

Transformer-Parameters

Name Name of element. Type Applicable only with a transformer library. Pressing the


Un1 () Nominal voltage of the primary winding node (just for information).

Un2 () Nominal voltage of the secondary winding node (just for information).

Ur1, Ur2 () Rated voltage of the primary and secondary winding, based on the transformation ratio.

Sr () Rated power in MVA. URr(1) () Rated positive sequence copper losses of winding 1

and 2 in % with respect to Sr and Ur1 at tap = tap r. Ukr(1) () Rated positive sequence short circuit voltage in % with

respect to Sr and Ur1 at tap = tap r. URr(0) SP Rated zero sequence copper losses for winding 1 and 2

in % with respect to Sr and Ur1 at tap = tap r. Ukr(0) SP Rated zero sequence short circuit voltage in % with

respect to Sr and Ur1 at tap = tap r. U01(0) SP Rated zero sequence open circuit voltage in % with

respect to Sr and Ur1 at tap = tap r and primary side (feeding from primary side).

U02(0) SP Rated zero sequence open circuit voltage in % with respect to Sr and Ur1 at tap = tap r and secondary side (feeding from secondary side).

I0 LMDR Open circuit current in % with respect to Sr and Ur1. P fe LMDR Iron core losses in kW. On-load tapchanger

LMDR If checked, the on-load tapchanging transformers will be regulated automatically during load flow calculation. This parameter is also considered for the impedance correction in the short circuit calculation according to IEC60909.



Unit transformer

SP Indicates whether the transformer is part of a power station unit.

Compens. Winding

SP Indicates, whether the two-winding transformer has a compensation winding. If there is one, the YY-trans-former will be modeled according to Fig. 4.8.

Switchable L Indicates whether the optimal separation point proce-dure is allowed to connect or disconnect this element.

Vector Group

SP Wiring of the windings in nodes 1 and 2. Default value is YD.05. The common vector groups can be selected from a list. The vector groups can be entered according to:

• NEPLAN-Format: After the winding designations a point and then voltage phase shifting. E.g. YY.00, YD.05, YZ.5

• DVG-Format: If the neutral is brought out, a N or n must be set after the corresponding winding designation. E.g. YNYn, YND5, YNZn5

pTap LMDR Deviation in % of transformer ratio from nominal Tap. Only necessary for Short Circuit calculations by IEC60909 (2001) and for transformers without on-load tap-changer, which make part of a power station unit.

Operating values before SC Operat. values active

SP For Short Circuit calculation with the norm IEC60909 (2001) an impedance correction factor is introduced in the calculation equations. Check this box, if longterm operating conditions before the short circuit are known, and the correction factor shall be calculated by using the following parameters.

Secondary values Ub max SP Highest operating voltage in kV, before short circuit. Ib max SP Highest operating current in A, before short circuit. Cos(phi) SP Angle of power factor, before short circuit. Primary value Ub min SP Lowest operating voltage in kV, before short circuit.

Transformer-Limits

Name Name of element.



Evaluation according to Ir or Sr

LM The user can select the criteria for the calculation of the transformer loading. If Ir is activated the current (Ir min or Ir max) is taken, if Sr is activated the power (Sr min or Sr max) is taken as reference.

Ir1 min LM Minimal current in A for the calculation of the transformer loading on the primary winding. The loading can be calculated according to Ir min or Ir max (see load flow calculation parameters).

Ir1 max LM Maximal current in A for the calculation of the transformer loading on the primary winding. The loading can be calculated according to Ir min or Ir max (see load flow calculation parameters).

Ir2 min LM Minimal current in A for the calculation of the transformer loading on the secondary winding. The loading can be calculated according to Ir min or Ir max (see load flow calculation parameters).

Ir2 max LM Maximal current in A for the calculation of the transformer loading on the secondary winding. The loading can be calculated according to Ir min or Ir max (see load flow calculation parameters).

Sr min LM Minimal power in MVA for the calculation of the transformer loading. The loading can be calculated according to Sr min or Sr max (see load flow calculation parameters).

Sr max LM Maximum power in MVA for the calculation of the transformer loading. The loading can be calculated according to Sr min or Sr max (see load flow calculation parameters).

Transformer-Regulation

Name Name of element. Tap side LMDR Indicates if the tap location of the tap changer is on the

primary or secondary side. Controlled node

LMDR Indicates if the voltage is controlled at the primary or at the secondary node of the transformer or if there is a remote control. With the remote control option, a neighboring node can be controlled with the transformer. The controlled node can be selected from a list (press "").

Tap min LMDR Minimum tap settings of the regulated transformer.



Tap r LMDR Rated tap setting. Tap max LMDR Maximum tap settings of the regulated transformer. Tap act LMDR Actual tap setting. This value is used to calculate the

ratio of the transformer. Tap act = Tap r has to be set, if the ratio is equal t = Ur1/Ur2.

Ukr(1),Ukr(0) Tap min

() Positive and zero sequence short circuit voltage in % with respect to Sr and Ur1 at tap = tap min.

Ukr(1),Ukr(0) Tap r

() Rated positive and zero sequence short circuit voltage in % with respect to Sr and Ur1 at tap = tap r.

Ukr(1),Ukr(0) Tap max

() Positive and zero sequence short circuit voltage in % with respect to Sr and Ur1 at tap = tap max.

Ukr(1),Ukr(0) Tap act

() Calculated positive and zero sequence short circuit voltage in % with respect to Sr and Ur1 at tap = tap act. These values are calculated with a quadratic interpola-tion between Ukr of tap min and tap max. During a load flow calculation the short circuit voltage will be adapted according to the tap of the automatically tap changer.

Delta U LMDR Magnitude of the additional voltage per tap step on the tap location side. This value must be given in % of the rated voltage on the tap location side of the transformer. A negative value can be entered. In this case the taps are mirrored (see below).

U set LMDR Setting voltage in % of nominal voltage of the controlled node. This value can also be entered in the node mask (see "Node Data Input"). This value will be a function of the load current, if com-pounding is active. The value must be between Umin and Umax (see below). The transformer will regulate to this voltage if the "Auto regulated" option (Params tab) is checked.

Beta LMDR Angle in ° of the additional voltage on the tap location side.

P set LMDR Regulated power flow of primary winding in % with respect to Sr. For negative power flow insert negative value. This value is only valid for phase shifting trans-formers (Angle Beta > 0.0).

Compounding Active LMDR Indicates, if compounding is active or not (see below). If

the compounding is not active, the set value will be kept constant at Uset.



Imin LMDR Minimal load current in % of the rated transformer current at the controlled side.

Imax LMDR Maximum load current in % of the rated transformer current at controlled side.

Umin LMDR Minimal voltage of the controlled node in %. The value Unom must be between Umin and Umax (see above).

Umax LMDR Maximum voltage of the controlled node in %. The value Unom must be between Umin and Umax (see above).

Transformer-Earthing

Name Name of element. Primary side SP The user can choose between three types of earthing

for the primary side: direct, impedance, isolated. Re1, Xe1 SP Real- and imaginary part of earthing impedance of side

1 in Ohm. (only for impedance earthing) Secondary side

SP The user can choose between three types of earthing for the secondary side: direct, impedance, isolated.

Re2, Xe2 SP Real- and imaginary part of earthing impedance of side 2 in Ohm. (only for impedance earthing)

Active SP For the primary and the secondary side, the user can define, which portion in % of the earthing impedance is active.

Transformer-Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Transformer-Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.



Transformer-User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

Transformer-More… Frequency dependence… By pressing this button of the More tab, the Frequency dependence input parameters can be entered. They are only used for harmonic analysis. The description can be found in Frequency dependence of chapter Data Input Dialogs of Network Elements-Element - More on page 4-4. Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6.

Regulation: Tap settings The following table shows different possibilities to enter Delta U and to define the Tap changer side.

Delta U positive Constant voltage at primary side

Tap changer at primary side

Tap changer at secondary side

Tap act = Tap min highest secondary voltage

lowest secondary voltage

Tap act = Tap max lowest secondary voltage

highest secondary voltage

Delta U negative Constant voltage at primary side

Tap changer at primary side

Tap changer at secondary side

Tap act = Tap min lowest secondary voltage

highest secondary voltage

Tap act = Tap max highest secondary voltage

lowest secondary voltage



Compounding If compounding and automatic voltage regulation is active, the set value for the voltage of the controlled node will be changed in function of the transformer load current and according to the characteristic below:

Uset

Imin Imax

Umin

Umax

Itr

Fig. 4.6 Compounding Characteristic

Uset means the set value for the regulated node voltage. Itr is the current, which flows through the transformer during the calculation. If Itr is zero, the set value for the regulated node voltage is the same as the entered value. Possible values are: Umin = 95%, Umax = 105%, Imin=Imax=80%.

Recommended Values for Transformer Zero Sequence Reactances: The ratio between the reactances of the positive and zero sequence are dependent on the core structure and of the vector group of the transformer:

Vector group Yz with earthing at z -winding

for all transformer types:

X(0)/X(1) = 0.1 .. 0.15

Vector group Dy- or Yd with earthing at y-winding

3-salient pole core: 5-salient pole core: 3 one pole transformers:

X(0)/X(1) = 0.7 .. 1.0 (Sr small: X(0)/X(1) = 1.0) X(0)/X(1) = 1.0 X(0)/X(1) = 1.0

Vector group Yy with compensation winding and earthing at y-winding

for all transformer types:

X(0)/X(1) = 1.0 .. 2.4 1)

Vector group Yy- or Yz without compensation

3-salient pole core: X(0)/X(1) = 3.0 .. 10.0 1)



winding and earthing at y-winding:

5-salient pole core: 3 one pole transformers:

X(0)/X(1) = 10.0 .. 100.0 1) X(0)/X(1) = 10.0 .. 100.0 1)

1) Very dependent on the transformer's structure and the ratio between the leakage flux to useful flux (the leakage flux goes partly through the transformer tank).

Remark: Regulated transformers are only regulated automatically during load flow calculation, when the "Auto regulated" option in the Params tab is checked.

Description of the Model (Transformer) The models for load flow, short circuit and harmonic analysis calculations are different. The following figure shows the model of a transformer for load flow calculation.

R X

Y/2Y/2

t : 1

Fig. 4.7 Model of a transformer for load flow calculation The model parameters of the positive sequence are calculated as follows: Positive sequence

Z = Ukr(1)·Ur1²/(Sr·100) R = URr(1)·Ur1²/(Sr·100) X = √(Z²-R²) YFe = PFe/Ur1² Y0 = I0·Sr/(100·Ur1²) Y = YFe - j·√(Y0²-YFe²)



Calculation of Regulated Transformer The voltage and ratio are calculated as follows:

ß

Tap max

Tap min

Tap mit

Tap act

U

UrUr reg

Fig. 4.8 Regulated Transformer

Regulation on Primary Side Ur1reg = Ur1 + (Tapact - Tapr) ·Ur1·∆U/100·[cos(ß)+j·sin(ß)] treg = Ur1reg/Ur2 Regulation on Secondary Side Ur2reg = Ur2 + (Tapact - Tapr) ·Ur2·∆U/100·[cos(ß)+j·sin(ß)] treg = Ur1/Ur2reg If ß = 0 the voltage can be controlled. If ß = 90 the active power can be controlled. If 0 < ß < 90 the power or the voltage can be controlled.

Transformer Model for Short Circuit Calculation The following figure shows the transformer model for a short circuit calculation of positive sequence.

R X

t : 1



Fig. 4.9 Transformer model for short circuit calculation of positive sequence The transformer model of the zero sequence is dependent on the vector group (see Fig. 4.8 - 4.10).

t : 1

3 · Ze1 Z 3 · Ze2

If Ze1 < 100.0 and Ze2 >>:

3 · Ze1 Z

If U01(0) ≠ 0.0 and U02(0) ≠ 0.0:

t : 1

3 · Ze1 Z1 3 · Ze2Z2

Zh

Fig. 4.10 Transformer model for short circuit calculation (vector group YY) of zero sequence



3 · Ze1

Z

Fig. 4.11 Transformer model for short circuit calculation (vector group YD or ZY) of zero sequence

Fig. 4.12 Transformer model for short circuit calculation (vector group DD) of zero sequence The model parameters of the positive and zero sequence are calculated as follows: Positive sequence Zero sequence Z = Ukr(1)·Ur1²/(Sr·100) Z = Ukr(0)·Ur1²/(Sr·100) R = URr(1)·Ur1²/(Sr·100) R = URr(0)·Ur1²/(Sr·100) X = √(Z²-R²) X = √(Z²-R²) Z = R + j·X Z = R + j·X Ze1 = Re1 + j·Xe1 Ze2 = Re2 + j·Xe2 Z10 = U01(0)·Ur1²/(Sr·100)

X10 = √(Z10²-R²) Z10 = R + j·X10

Z20 = U02(0)·Ur1²/(Sr·100) X20 = √(Z20²-R²) Z20 = R + j·X20



The impedances Z1, Z2 and Zh in Fig. 4.8 can be calculated from the following equations (Ze1=Ze2=0.0): Z10 = Z1 + Zh

Z20 = Z2 + Zh Z = Z1 + Z1·Z2 / (Z1+Z2) ≈ Z1 + Z2

Z10, Z20 and Z are input values and given above.

Note: For Short circuit calculations according to IEC the impedance Z will be multiplied by a correction K: IEC909 (1988) Unit transformer: K = cmax / 2 / Network transformer: K = 1.0 IEC60909 Unit transformer with on-load tapchanger:

rGTrTHV

rTLV

rG

n

xxdc

UU

UU

Kϕsin1 "

max2

2

2

2

⋅−+⋅⋅=

Unit transformer without on-load tapchanger:

( ) ( )rG

TrTHV

rTLV

GrG

n

xdc

pUU

pUU

Kϕsin1

11 "

max

⋅+⋅±⋅⋅

+⋅=

Network transformer:

xTcK

⋅+⋅=

6.0195.0 max or

br

bb

n

IIxT

cUU

Kϕsin1

max

⋅

⋅+

⋅=

with Un Nominal system voltage of connecting node Ub Highest operating voltage before SC Ib Highest operating current before SC phib Angle of power factor before SC Ir Rated current of transformer xT Transformer reactance cmax maximum voltage factor UrTLV Transformer rated voltage on low-voltage side



UrTHV Transformer rated voltage on high-voltage side UrG Rated voltage of unit generator pG Deviation of generator terminal voltage from rated voltage (1+pT) Used off-load tap



Asymmetrical Transformer

This chapter describes the parameters of the Data Input Dialog of an asym-metrical transformer and the corresponding transformer model.

Asym. Transformer-Parameters

Name Name of element. Type Applicable only with an asymmetrical transformer

library. Pressing the button "", the type may be chosen and the data can be transferred from the predefined library.

Switchable L Indicates whether the optimal separation point proce-dure is allowed to connect or disconnect this element.

Negative polarity

LMDR Mark this checkbox, if you wish the transformer to have negative polarity, like shown below.

positive polarity

negative polarity

L

N

L

L

N

NN

L

Un1 () Nominal voltage of the primary winding node (just for

information). Un2 () Nominal voltage of the secondary winding node (just for

information). Ur1, Ur2 () Rated voltage of the primary and secondary winding,

based on the transformation ratio. When the phase configuration is Phase to Neutral (L1N, L2N or L3N), then the value for the rated voltage Ur has to be given as a phase to earth value.

Sr () Rated power in MVA. URr(1) () Rated positive sequence copper losses of winding 1

and 2 in % with respect to Sr and Ur1 at tap = tap r. Ukr(1) () Rated positive sequence short circuit voltage in % with

respect to Sr and Ur1 at tap = tap r. I0 LMDR Open circuit current in % with respect to Sr and Ur1.



P fe LMDR Iron core losses in kW. Phases () Indicates the phases of the transformer on primary and

secondary side. If the input of the phases and the input of the vector group don't match together, the phase indication will be decisive. When the phase configuration is Phase to Neutral (L1N, L2N or L3N), then the value for the rated voltage Ur has to be given as a phase to earth value.

Vector Group

() The following vector groups may be chosen: 1.) E E 2.) E 2E 3.) 2E E

The transformer side with E has a Phase-Phase or Phase-Neutral connection. The transformer side with 2E has a Phase-Neutral-Phase connection. See the model of the asymmetrical transformer.

Regulation Tap min LMDR Minimum tap settings of the regulated transformer. Tap r LMDR Rated tap setting. Tap max LMDR Maximum tap settings of the regulated transformer. Tap act LMDR Actual tap setting. This value is used to calculate the

ratio of the transformer. Tap act = Tap r has to be set, if the ratio is equal t = Ur1/Ur2.

Delta U LMDR Magnitude of the additional voltage per tap step on the tap location side. This value must be given in % of the rated voltage on the tap location side of the transformer. A negative value can be entered. In this case the taps are mirrored (see below).

Tap side LMDR Indicates, if the tap location of the tap changer is on the primary or secondary side.

Controlled bus

LMDR Indicates, if the voltage is controlled on primary or on secondary side of the transformer.

U set LMDR Setting voltage in % of nominal voltage of the controlled node. This value can also be entered in the node mask (see "Node Data Input"). The transformer will regulate to this voltage if the "Auto regulated" option is checked.

Auto LMDR Indicates whether the transformer should be regulated



regulated automatically for the load flow calculation.

Asym. Transformer-Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Asym. Transformer-Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Asym. Transformer-User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

Asym. Transformer-More… Frequency dependence… By pressing this button of the More tab, the Frequency dependence input parameters can be entered. They are only used for harmonic analysis. The description can be found in Frequency dependence of chapter Data Input Dialogs of Network Elements-Element - More on page 4-4. Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6

Description of the Model (Asymmetrical Transformer) Depending of the vector group of the asymmetrical transformer, E/E or 2E/E, the following models are valid:



X

Yh/2 Yh/2

X

Yh/4 Yh/4

X

Yh/4 Yh/4

U1S

U1R

U1N

U2S

U2R 1 : 2a

1 : 2a

t : 1 a) Model E/E

b) Model 2E/E

Fig. 4.13 Model of the asymmetrical transformer



Three Windings Transformer

This chapter describes the parameters of the Data Input Dialog of a three windings transformer and the corresponding transformer model.

3W-Transformer-Parameters

Name Name of element. Type Applicable only with a 3W-Transformer library.

Pressing the button "", the type may be chosen and the data can be transferred from the predefined library.

Un1 () Nominal voltage of the primary winding node (just for information).

Un2 () Nominal voltage of the secondary winding node (just for information).

Un3 () Nominal voltage of the tertiary winding node (just for information).

Ur1, Ur2, Ur3 () Rated voltage of the primary, secondary and tertiary winding, based on the transformation ratio.

Sr12, Sr23, Sr31 () Rated power in MVA. 12: primary-secondary, 23: secondary-tertiary, 31: tertiary-primary.

URr(1)12, 23, 31 () Rated positive sequence copper losses in % with respect to Sr12, Sr23, Sr31 and Ur1, Ur2, Ur3.

Ukr(1)12, 23, 31 () Rated positive sequence short circuit voltage with respect to Sr12, Sr23, Sr31 and Ur1, Ur2, Ur3.

Ukr(0) 12,23,31 SP Rated zero sequence short circuit voltage with respect to Sr12, Sr23, Sr31 and Ur1, Ur2, Ur3.

I0 LMDR Open circuit current in % with respect to Sr12 and Ur1. This value is only considered in the Loadflow calculation, method Extended Newton Raphson.

P fe LMDR Iron core losses in kW. This value is only considered in the Loadflow calculation, method Extended Newton Raphson.

Auto regulated LMDR Indicates if the transformer in the load flow calculation should be automatically regulated. The



following is assumed, when calculating the Loadflow with Newton Raphson or Current Iteration method: If the box is checked, the program assumes a two-windings transformer with a compensation winding. In this case the model of a two-winding transformer is taken (see "Transformer" on page 4-38). The tertiary node will be neglected. No load can be connected to the tertiary node.

Compens. Winding

SP Indicates, whether the three-winding transformer has a compensation winding. If there is one, the YYY-transformer will be accurately modeled in the zero system.

Vector group SP Winding connection in nodes 1, 2 and 3. The winding coefficient has to be given, with respect to node 1 according to VDE 0532/1. The common vector groups can be selected from a list. The vector groups can be entered according to:

• NEPLAN-Format: After the winding designations a point and then voltage phase shiftings, which are also separated with a point. The coefficient of the winding in node 1 must be set to zero or it can be neglected (e.g. YYD.0.5 instead of YYD.0.0.5).

• DVG-Format: If the neutrals are brought out, a N or n must be set after the corresponding winding designation. E.g. YNYn0d5

3W-Transformer-Limits

Name Name of element. Ir 1,2,3 min LM Minimal current on primary, secondary and tertiary

side in A for the calculation of the transformer loading. The loading can be calculated according to Sr min or Sr max resp. Ir min or Ir max (see load flow calculation parameters).

Ir 1,2,3 max LM Maximum current on primary, secondary and tertiary side in A for the calculation of the transformer loading. The loading can be calculated according to Sr min or Sr max resp. Ir min or Ir max



(see load flow calculation parameters). Sr min LM Minimal power in MVA for the calculation of the

transformer loading. The loading can be calculated according to Sr min or Sr max resp. Ir min or Ir max (see load flow calculation parameters).

Sr max LM Maximum power in MVA for the calculation of the transformer loading. The loading can be calculated according to Sr min or Sr max resp. Ir min or Ir max (see load flow calculation parameters).

Evaluation acc. to Sr or Ir

LM The user can select the criteria for the calculation of the transformer loading. If Ir is activated the currents (Ir 1,2,3 min or Ir 1,2,3 max) are taken, if Sr is activated the power (Sr min or Sr max) is taken.

3W-Transformer-Regulation

1st Regulation Tap side LMDR Indicates if the tap location of the tap changer is on

the primary, secondary or tertiary side. Controlled node LMDR The node to be controlled must be selected from a

list, press "". If there is no node selected, the tap location node will be controlled. Remote control: A neighboring node can also be controlled with the transformer. The controlled node can be selected from a list (press ""). Remote control is only possible if the input field "Transf.regul." is set to YES.

Tap min LMDR Minimum tap settings of the regulated transformer. Tap max LMDR Maximum tap settings of the regulated transformer. Tap r LMDR Rated tap setting. Tap act LMDR Actual tap setting. This value is used to calculate

the ratio of the transformer. For the tap calculation see "Transformer" on page 4-38.

Ukr(1) 12,23,31 Ukr(0) 12,23,31 Tap min

() Positive and zero sequence short circuit voltage in % with respect to Sr12, Sr23, Sr31 and Ur1, Ur2, Ur3 at tap = tap min.

Ukr(1) 12,23,31 () Rated positive and zero sequence short circuit



Ukr(0) 12,23,31 Tap r

voltage in % with respect to Sr12, Sr23, Sr31 and Ur1, Ur2, Ur3 at tap = tap r.

Ukr(1) 12,23,31 Ukr(0) 12,23,31 Tap max

() Positive and zero sequence short circuit voltage in % with respect to Sr12, Sr23, Sr31 and Ur1, Ur2, Ur3 at tap = tap max.

Ukr(1) 12,23,31 Ukr(0) 12,23,31 Tap act

() Positive and zero sequence short circuit voltage in % with respect to Sr12, Sr23, Sr31 and Ur1, Ur2, Ur3 at tap = tap act. These values are calculated with a quadratic interpolation between ukr of tap min and tap max.

dU LMDR Magnitude of the additional voltage per tap step on the tap location side. This value must be given in % of the rated voltage on the tap location side of the transformer. A negative value can be entered. In this case the taps are mirrored (see "Transformer" on page 4-38).


P set LMDR Regulated power flow of primary winding in % with respect to Sr12. For negative power flow insert negative value. This value is only valid for phase shifting transformers (Angle Beta > 0.0) and if the option "Auto regulated" is checked.

U set LMDR Setting voltage in % of nominal voltage of the controlled node. This value can also be entered in the node mask (see "Node Data Input"). This value will be a function of the load current, if compounding is active. The value must be between Umin and Umax (see below). The transformer will regulate to this voltage if the option "Auto regulated" (Params tab) is checked.

2nd Regulation Tap side LMDR Indicates if the tap location of the tap changer is on

the primary, secondary or tertiary side. It can't be the same winding as in the 1st regulation. The taps of the 2nd regulation can only be changed manually (it won't be automatically).

Tap min LMDR Minimum tap settings of the 2nd tap changer. Tap max LMDR Maximum tap settings of the 2nd tap changer. Tap r LMDR Rated tap setting.



Tap act LMDR Actual tap setting. This value is used to calculate the ratio of the transformer.

dU LMDR Magnitude of the additional voltage per tap step on the tap location side. This value must be given in % of the rated voltage on the tap location side of the transformer. A negative value can be entered. In this case the taps are mirrored (see below).


3W-Transformer-Earthing

Name Name of element. Primary side () The user can choose between three types of

earthing for the primary side: direct, impedance, isolated.


Secondary side SP The user can choose between three types of earthing for the secondary side: direct, impedance, isolated.


Tertiary side SP The user can choose between three types of earthing for the tertiary side: direct, impedance, isolated.


Active SP It's possible to define, which portion in % of the earthing impedance is active on primary, secondary and tertiary side.

3W-Transformer-Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.



3W-Transformer-Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

3W-Transformer-User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

3W-Transformer-More… Frequency dependence… By pressing this button of the More tab, the Frequency dependence input parameters can be entered. They are only used for harmonic analysis. The description can be found in Frequency dependence of chapter Data Input Dialogs of Network Elements-Element - More on page 4-4. Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6

Description of the Model (3-W Transformer) The three windings transformer will be modeled by three two windings transformer (models see "Transformer" on page 4-38). The calculation of the model parameters is: Positive sequenze Zero sequence Zij = Ukr(1)ij·Uri²/(Srij·100) Zij = Ukr(0)ij·Uri²/(Srij·100) Rij = URr(1)ij·Uri²/(Srij·100) Rij = 0 Xij = √(Zij²-Rij²) Xij = Zij Zij = Rij + j·Xij Zij = j·Xij ij ε 12, 23, 31 i ε 1, 2, 3



Ze1 = Re1 + j·Xe1 Ze2 = Re2 + j·Xe2 Ze3 = Re3 + j·Xe3

Z1 Z2

Z3

1 2 4

3 Z1 = 0.5 * (Z12 + Z13 Z23) Z2 = 0.5 * (Z23 + Z12 Z13) Z3 = 0.5 * (Z13 + Z23 Z12) The ficticious node 4 will be internally reduced, thus a 3 winding transformer will be represented by a 3x3 matrix.



Four Windings Transformer

This chapter describes the parameters of the Data Input Dialog of a 4W-Transformer and the corresponding transformer model.

4W-Transformer-Parameters

Name Name of element. Type Applicable only with a 4W-Transformer library.


Un1, Un2, Un3, Un4

() Nominal voltage of the primary, secondary, tertiary and 2. tertiary winding node.

Ur1, Ur2, Ur3, Ur4

() Rated voltage of the primary, secondary, tertiary and 2. tertiary winding, based on the transformation ratio.

Sr1, Sr2, Sr3, Sr4

() Rated power in MVA of the primary, secondary, tertiary and 2. tertiary winding

URr(1)12, 13, 14, 23, 24, 34

() Rated positive sequence copper losses in % with respect to Sr4 and Ur1, Ur2, Ur3, Ur4.

Ukr(1)12, 13, 14, 23, 24, 34

() Rated positive sequence short circuit voltage with respect to Sr4 and Ur1, Ur2, Ur3, Ur4.

Ukr(0)12, 13, 14, 23, 24, 34

SP Rated zero sequence short circuit voltage with respect to Sr4 and Ur1, Ur2, Ur3, Ur4.

Vector group SP Winding connections in nodes 1, 2, 3 and 4. The winding coefficient has to be given, with respect to node 1 according to VDE 0532/1. The common vector groups can be selected from a list. The vector groups can be entered according to:

• NEPLAN-Format: After the winding designations a point and then voltage phase shifting. E.g. YY.00, YD.05, YZ.5

• DVG-Format: If the neutral is brought out, a N or n must be set after the corresponding winding designation. E.g. YNYn, YND5, YNZn5



4W-Transformer-Regulation There is no automatic regulation possible for the 4W-Transformer. The tap have to be changed manually.

Name Name of element. Tap side LMDR Indicates if the tap location of the tap changer is on

the primary, secondary, tertiary or 2. tertiary side. Tap min LMDR Minimum tap settings of the tap changer. Tap max LMDR Maximum tap settings of the tap changer. Tap r LMDR Rated tap setting. Tap act LMDR Actual tap setting. This value is used to calculate

the ratio of the transformer. For the tap calculation see "Transformer" on page 4-38.

dU LMDR Magnitude of the additional voltage per tap step on the tap location side. This value must be given in % of the rated voltage on the tap location side of the transformer. A negative value can be entered. In this case the taps are mirrored (see "Transformer" on page 4-38).

4W-Transformer-Earthing

Name Name of element. Primary side () The user can choose between three types of

earthing for the primary side: direct, impedance, isolated.


Secondary side () The user can choose between three types of earthing for the secondary side: direct, impedance, isolated.


Tertiary side () The user can choose between three types of earthing for the tertiary side: direct, impedance, isolated.


2. Tertiary side () The user can choose between three types of earthing for the tertiary side: direct, impedance,



isolated. Re4, Xe4 SP Real- and imaginary part of earthing impedance of

side 4 in Ohm. (only for impedance earthing) Active SP It's possible to define, which portion in % of the

earthing impedance is active on primary, secondary and tertiary and 2. tertiary side.

4W-Transformer-Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

4W-Transformer-Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3

4W-Transformer-User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

4W-Transformer-More… Frequency dependence… By pressing this button of the More tab, the Frequency dependence input parameters can be entered. They are only used for harmonic analysis. The description can be found in Frequency dependence of chapter Data Input Dialogs of Network Elements-Element - More on page 4-4. Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6.



Description of the Model (4W-Transformer) The four windings transformer will be modeled by four two windings transformer (models see "Transformer" on page 4-38). The calculation of the model parameters is: Positive sequence Zero sequence Zij = ukr(1)ij·Uri²/(Sr4·100) Zij = ukr(0)ij·Uri²/(Sr4·100) Rij = uRr(1)ij·Uri²/(Sr4·100) Rij = 0 Xijij = √(Zijij²-Rij²) Xij = Zij Zij = Rij + j·Xij Zij = j·Xij ZEi = REi + j·Xei

ij ε 12, 13, 14, 23, 24, 34 ; i ε 1, 2, 3 e.g. Z24 = ukr(1)24·Ur2²/(Sr4·100)



Shunt

This chapter describes the parameters of the Data Input Dialog of a shunt and the corresponding shunt model.

Shunt-Parameter

Name Name of element. Type Applicable only with a shunt library. Pressing the button

"", the type may be chosen and the data can be transferred from the predefined library

Control mode

() There are three different type of control modes: • fixed: The shunt consists of a fixed value of active

and reactive power. • discrete: The shunt consists of various shunt

elements, which will be connected or disconnected, depending on the regulated voltage.

• continuously: The shunt will be able to change the reactive power continuously, without steps, in the defined range.

Ur () Rated voltage in V. Fixed admittance P(1) () Positive sequence active power in MW. Dependent on

the phase connectivity (see Info tab) the value must be entered as phase value.

Q(1) () Positive sequence reactive power in Mvar. Q(1) is negative for a capacitive load. Dependent on the phase connectivity (see Info tab) the value must be entered as phase value.

P(0) SP Zero sequence active power in MW. This value has not to be entered when entering an asymmetrical shunt. It will be calculated.

Q(0) SP Zero sequence reactive power in Mvar. Q(0) is negative for a capacitive load. This value has not to be entered when entering an asymmetrical shunt. It will be calculated.

Operating mode

() Indicates if the shunt is capacitive or inductive, depending on the sign of the entered reactive power Q. (negative value means capacitive mode, positive value means inductive mode)



Effective Q-scaling factor

() Depending on the operational mode, the predefined scaling factors for capacitive or inductive Q are taken to calculated the effective scaling factor, which is displayed in this field. The predefined scaling factors for the network and zones may be modified in Data - Operational Data of the menu Edit (see chapter Menu Options). The user cant define User Defined Scaling Factors for the shunts.

Switched admittance blocks Remote controlled

LMDR Check this option, if an other node than the shunt node has to be controlled. By mouse click on the remote node may be chosen from a list.

U set LMDR Setting voltage in % of nominal voltage of the controlled node. This value can also be entered in the node mask (see "Node Data Input").

Switched admittance blocks

LMDR There may be defined blocks of reactive power, each one of which consists of various steps.

Remarks: The switched shunt elements at a bus may consist entirely of reactors (all admittance blocks have positive values for dQ) or entirely of capacitor banks (all admittance blocks have negative values for dQ). In these cases, the shunt blocks are specified in the order in which they are switched on the bus. If the switched shunt devices at a bus are a mixture of reactors and capacitors, the reactor blocks are specified first in the order in which they are switched on, followed by the capacitor blocks in the order in which they are switched on. The difference between the continuous and the discrete regulation is only, that for the continuous mode, the reactive power can vary continuously in the whole defined range, without steps.

Shunt-Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2. The option Phases has additional possibilities because shunts may be placed as well between phases:

Phases () Indicates the phasing of the element. Possible values are:



- L1L2L3N: Symmetrical shunt impedance - L1N: Single phase shunt impedance, phase L1 - L2N: Single phase shunt impedance, phase L2 - L3N: Single phase shunt impedance, phase L3 - L1L2: Impedance between phases L1 and L2 - L1L3: Impedance between phases L1 and L3 - L2L3: Impedance between phases L2 and L3

Shunt-Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Shunt-User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

Shunt-More… Frequency dependence… By pressing this button of the More tab, the Frequency dependence input parameters can be entered. They are only used for harmonic analysis. The description can be found in Frequency dependence of chapter Data Input Dialogs of Network Elements-Element - More on page 4-4. Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6.

Description of the Model (Shunt)



R

X

Fig. 4.14 Model of shunt The model parameters of the positive and zero sequence are calculated as follows: Positive sequence Zero sequence R = P(1)·Ur²/(P(1)²+Q(1)²) R = P(0)·Ur²/(P(0)²+Q(0)²) X = Q(1)·Ur²/(P(1)²+Q(1)²) X = Q(0)·Ur²/(P(0)²+Q(0)²)

If Q(1) is given as a negative value, in the module Harmonic analysis the following is taken for X:

X = -1.0 / X (capacitive). If an asymmetrical shunt has been entered, the program will transform the parameters from the phase into the symmetrical component system with the transformation matrix.



Converter

This chapter describes the parameters of the Data Input Dialog of a Converter and the corresponding Converter model.

Converter-Parameters

Name () Name of the converter. Type () Converter type Rectifier, Inverter

() Indicates, if the converter is a - Rectifier - Inverter

Regulation Regulation () The converter can be

P: Power regulated I: Current regulated A+U: Voltage and angle regulated

Pset () Set value for power regulation in MW. Umode () Minimum voltage for power regulation (for voltages below

Umode control shifts to constant current with Iset =Pset/Uset)

Iset () Set value for current regulation in kA. Uset () Set value for voltage regulation in kV. In case of power

regulation Uset denotes the voltage used for calculating the new setvalue at the control mode shift (see Umode).

Firing angle Teta set () Set value for the rectifier firing or inverter margin angle in

°. This value is only valid for A+U regulated converter Teta min () Minimum value for the rectifier firing or inverter margin

angle in °. Teta max () Minimum value for the rectifier firing or inverter margin

angle in °. Transformer Transformer integrated

() Indicates, if the converter transformer should be included in the converter. If clicked, no external transformer must be defined, the converter represents a converter plus a



transformer. T () Nominal tap ratio of the converter transformer in pu from

DC to AC side. Tap locked () If this parameter is checked the tap will be fixed on T. dT () Converter transformer tap-step in pu. T min () Minimum value of converter transformer tap ratio in pu. T max () Maximum value of converter transformer tap ratio in pu. negative pole

() The converter is a negative pole

positive pole () The converter is a positive pole numb. bridges

() Number of three-phase converter bridges in series

Xc () Commutating reactance in Ohm. RLoss () Equivalent total active power losses in the valves and

auxiliaries in Ohm. This parameter is only considered in Loadflow calculation, method Extended Newton Raphson.

Vdrop () Voltage drop across the valves in V. This parameter is only considered in Loadflow calculation, method Extended Newton Raphson.

Im () Current margin in % of the current set value Iset. Im distrib. () This is the converter participation factor in % in case of a

multi-terminal system. If the current order at any rectifier is reduced, current orders of remaining converters are modified in proportion by these factors.

Grounding node

() Name of grounding node in case of a bipole HVDC link. One corresponding negative and positive pole of a terminal must have the same grounding node.

Rg () Grounding resistance in Ohm.

Converter-Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.



Converter-Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Converter-User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

Converter-More… Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6.

Description of the Model (Converter) Every HVDC system consists of rectifiers and inverters, which are called converter. The basic equations for a converter are (rectifier):

( ) dropdldcdd VIRIBTXUU −⋅−⋅⋅⋅⋅−⋅=π

α 3cos0 with acd ETBU ⋅⋅⋅⋅=π

230

( )φπ

cos23 ⋅⋅⋅⋅⋅= acd ETBU

( )φtan⋅= acac PQ

dddac IUPP ⋅==

dac IBI ⋅⋅=π6

The equation for a DC line is:

ddcdrdi IRUU ⋅−= The abbreviations are: Ud: Converter DC voltage; Udi for inverter, Udr for rectifier Eac: Converter AC voltage Pac: Active power at AC terminal



Qac: Reactive power at AC terminal Iac: AC current Pd: DC power at DC terminal Vdrop: Voltage drop across the valves B: Number of bridges T: Transformer ratio from DC to AC Xc: Commutating reactance Rl: Losses in the valves Rdc: Resistance of the DC line Id: Converter DC current ϕ : AC power factor angle α : Firing angle (for rectifier) An equivalent circuit for a converter can be drawn as follows:

X c

E ac

1:T Idc

α

U d

Pac, Q ac

Fig. 4.15 Equivalent circuit of a converter The DC voltage Ud and/or the DC current Id are controlled by the firing angle alpha and the converter transformer ratio T. The firing angle and the transformer ratio (tap position) are varied within their limits.

HVDC Systems in NEPLAN NEPLAN can handle any number of two-terminal and multi-terminal HVDC systems. The following configurations are possible:

Fig. 4.16 Monopolar HVDC link



+

-

Fig. 4.17 Bipolar HVDC link

G G

Fig. 4.18 Meshed multi-terminal HVDC system In a two-terminal system, there are a rectifier and an inverter, one of them controls the DC voltage (normally the inverter) and one the DC current or DC power. In a multi-terminal system there is at least one converter, which controls the DC voltage. The normal operation of a two-terminal system can be described by the following diagram:



Udi

Im

Idrset Idi

Rectifier, current controlled

Udset

Inverter, voltage controlled

Operatingpoint

Fig. 4.19 Normal operation of a two-terminal system

In the normal mode of operation the margin angle of the inverter is adjusted to maintain the desired inverter DC voltage Udset. The ratios of the inverter and rectifier transformer are also adjusted, so that the firing angle alpha and the margin angle gamma are within their limits min and max. In the current controlling rectifier a voltage margin of about 3% is maintained in order to avoid frequent changes in control allocations. For that reason if the minimum firing angle for the rectifier is 5-7° the operating firing angle will typically have values

°≤≤° 1614 α . If the rectifier AC voltage is too low and the transformer ratio has reached the limit, the voltage control of the inverter will be abandoned. The inverter now will control the current: The current order Idiset at the inverter is lower than the current order Idrset (the current margin is defined as Im = Idrset - Idiset). The new operating point can be described as follows:



Udi

Im

Idrset Idiset

Udset

Inverter, current controlled

Operating point

Fig. 4.20 Current control of the inverter Analogous can be said for multi-terminal systems. The configuration considered is this of the parallel arrangement: The current in all the converter stations (of number n) except one are adjusted according to current or power control setpoints. One converter per pole (usually the one with the lower voltage ceiling) will control the voltage. Current control is also provided at the voltage setting terminal, so that it satisfies the following equation:

∑=

=nj

inmj IIset

..1arg

where Imargin is a positive quantity, and 0>jIset if j is a rectifier, 0<jIset if j is an inverter. In case of voltage depression in a current controlled converter, voltage control will be shifted to this converter and the current settings of the remaining terminals will be changed according to the participation factors jdistrib Im . If i denotes the converter that hits the minimum angle limit, the new current setpoint of any converter ij ≠ can be calculated using:

( ) ,∑

≠

⋅⋅+=

it

t

iijj

newj

aIsetmaisrecIsetIset

where 1=isrec if j is a rectifier and 1−=isrec if j is an inverter.



The coefficient ja is calculated using the following formula

Inverter if,nRecnInv

nRecSCoeff

.100/distrib Im

Rectifier if ,nRecnInv

nInvSCoeff

.100/distrib Im

j a

j a

jj

jj

+⋅=

+⋅=

where

.100/distibImSCoeff ∑∈

=Ci

i

and C all converters apart from the voltage controlling terminal that are not blocked.



SVC (Controlled static VAR Compensator)

This chapter describes the parameters of the Data Input Dialog of a SVC and the corresponding SVC model. The configuration assumed is that of a fixed capacitor and a thyristor controlled reactor.

SVC-Parameters

Name Name of element. Transformer LMDR Indicates if there is a transformer in the static VAR

system. U ref LMDR Reference voltage for the regulation. X sl LMDR Slope admittance: slope of the linear mode in the U/I

characteristic curve (see below). Qc max LMDR Maximal capacitive reactive power in Mvar.

Qcmax is a positive value and means the maximum generated inductive reactive power of the SVC at nominal voltage. Qcmax corresponds to the reactive power of the fix capacitor.

Ql max LMDR Maximal inductive reactive power in Mvar. Qlmax is a positive value and means the maximum consumed inductive reactive power of the SVC at nominal voltage. Qlmax corresponds to the maximum reactive power of the inductance Ql minus the maximum reactive power Qc max of the capacitor: Qlmax = Ql – Qcmax (see Fig. 4.13)

SVC-Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

SVC-Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.



SVC-User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

SVC-More… Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6.

Description of the Model (Static VAR Compensator) For load flow calculations a regulated VAR compensator can be described as follows:

C F L

Controller

VT

HV

LV

Transformer

SVC

I2

U2

U1

Qcmax

Ql

0

Fig. 4.21 Model of a SVC

F: Filter C: fix capacitor L: thyristor controlled reactor The elements filter, controlled reactor and capacitor will be modeled with the shunt element. The characteristic of a SVC is:



I2

U2

Umax

Umin

Uref

capacitive inductive

Qc max

Ql max

Imin Imax

∆U∆I ∆U/∆I=Xsl

Fig. 4.22 SVC characteristic curve

There are three modes: capacitive mode (U2 <= Umin): I2 = Bcap * U1 with Bcap = - Bc0 and Bc0 = Qcmax / U2n

2 ; Qcmax: input value inductive mode (U2 >= Umax): I2 = Bind * U1 with Bind = Bl0 - Bc0 and Bl0 = (Qcmax + Qlmax) / U2n

2 ; Qcmax, Qlmax : input values linear control range, normal mode ( Umin <= U2 >= Umax): I2 = (U2 - Uref)/Xsl for Xsl ≠ 0 ; Xsl : input value U2 = Uref for Xsl = 0 The equivalent circuits are:



XSL

I2 Uref Bcap

XT

I2

XT

I2 Bind

Linear mode Capacitive mode Inductive mode

U1 U2 U1 U2 U1 U2

Fig. 4.23 Equivalent circuits of a SVC XT: Reactance of the transformer The data of the transformer are entered separately. In the SVC, the user has to indicate only if there is a transformer or not by clicking the corresponding checkbox in the Data Input Dialog of the SVC. If there is no transformer, the regulated/controlled VAR compensator works like a PV-node with P=0.0 MW and U = Unom. This behaviour is similar to that of synchronous machines. The reactive power will be calculated. If the limits Qcmax .. Qlmax are reached, the regulated VAR compensator will be converted into a constant inductance or capacitance (see the figure above) and not into a PQ-node with Q = Qcmax or Q = Qlmax, like in the case of a synchronous machine. The input of Qcmax, Qlmax and the slope Xsl determine the characteristic of the SVC. If Qlmin <= Qcmax, the inductive mode is missed.

Remarks: When importing a project file (*.mcb) from version 4.2 or earlier the data of a SVC must be checked, because the data entry has changed.



STATCOM (Static Compensator)

This chapter describes the parameters of the Data Input Dialog of a Static Compensator (STATCOM) and the corresponding model.

STATCOM-Parameters

Name Name of element. Transformer LMDR Indicates if there is a transformer in the static VAR

system. U ref LMDR Reference voltage for the regulation. X sl LMDR Slope admittance: slope of the linear mode in the U/I

characteristic curve (see below). Imax C LMDR Maximal current for capacitive operation. Imax L LMDR Maximal current for inductive operation P(0) SP Zero sequence active power in MW. This value has not

to be entered when entering an asymmetrical shunt. It will be calculated.

Q(0) SP Zero sequence reactive power in Mvar. Q(0) is negative for a capacitive load. This value has not to be entered when entering an asymmetrical shunt. It will be calculated.

STATCOM-Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

STATCOM-Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

STATCOM-User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



STATCOM-More… Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6.

Description of the Model (Static Compensator) The STATCOM represents the GTO-based version of the SVC (see "SVC (Controlled static VAR Compensator)" on page 4-78). It consists of a Voltage Sourced Converter (VSC) behind a coupling transformer (see Figure below). The VSC generates a balanced set of sinusoidal voltages of controllable magnitude and phase angle. For load flow calculations the STATCOM can be described as follows:

STATCOM

Controller

VT

HV

LV

Coupling TransformerI2

U2

U1

DC Terminal Energy Storage (optional)

Multi-pulse Inverter

V Ref

Fig. 4.24 STATCOM configuration The voltage-current characteristic of the STATCOM is shown in the following figure.



I2

U2

Umax

Umin

Uref

capacitive

inductive Qc max

Ql max

Imin Imax

∆U∆I ∆U/∆I=Xsl

Fig. 4.25 STATCOM characteristic curve The STATCOM can provide both, inductive and capacitive vars and it is able to control its output current over the rated maximum capacitive or inductive range, independent of the AC System voltage. In the linear control range the functional capability of STATCOM is analogous to that of the SVC. Operation at the limits is however different: The SVC becomes an uncontrolled shunt reactance (capacitive or inductive) for which the current falls in proportion to the voltage whereas the STATCOM at full output behaves like a current source.



TCSC

This chapter describes the parameters of the Data Input Dialog of a TCSC (Thyristor Controlled Series Capacitor) and the corresponding model. The model assumes n (n >= 1) identical TCSC modules connected in series and controlled independently.

TCSC-Parameters

Name Name of element. Operation LMDR Indicates if there is one single TCSC module or several

modules in series. Module Parameters Xc LMDR Reactance of the capacitor in Ohm Xl LMDR Reactance of the inductor in Ohm X Limits, Teta Limits

LMDR Limits on total reactance of the TCSC or on Thyristor firing angle. In case of multi-module operation, only X Limits can be entered.

X min LMDR Minimum value of module reactance (negative for capacitive operation). The (X min,X max) range should not contain any resonance region.

X max LMDR Maximum value of module reactance (negative for capacitive operation). The (X min,X max) range should not contain resonance values.

Teta min LMDR Minimum value of thyristor firing angle. The (Teta min, Teta max) range should not contain resonance values.

Teta max LMDR Maximum value of thyristor firing angle. The (Teta min, Teta max) range should not contain resonance values.

Max. Volt. Drop

LMDR Maximum allowed voltage drop in kV.

Regulation P, I, Xtot, Transm. angle

LMDR Selection of the variable to be controlled. P: Line power flow I: Line current Xtot: Total TCSC reactance in Ohm Transm. Angle: Transmission angle



Pset LMDR Control value for line active power flow control in MW. Iset LMDR Control value for line current control in A. Xtot LMDR Control value for total TCSC reactance control in Ohm. Transm. angle

LMDR Control value for transmission angle (angle U1 angle U2) control in °.

TCSC-Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

TCSC-Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

TCSC-User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

TCSC-More… Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6.

Description of the Model (TCSC) The TCSC consists of a fixed capacitor connected in parallel with a thyristor controlled reactor (TCR) (see figure below). The TCR is the main control unit of the TCSC: By means of the firing angle of the thyristors, the effective inductive reactance of the TCR varies and causes rapid reactive power exchange between the TCR and the system. Depending on the system conditions



inductive or capacitive vars may be needed. To meet this requirement the variable inductor is usually connected in parallel with a fixed capacitor. A metal-oxide varistor is also connected in parallel for overvoltage protection.

Xc

Xl

MOV

I line

Fig. 4.26 Per phase TCSC module Firing angles are allowed to vary between 90° and 180°. For a certain firing angle the variable inductive reactance of the TCR equals in absolute value the capacitive reactance of the fixed capacitor Xc causing a resonance. Thyristors are fired sufficiently far away from the resonance value to avoid problems with control (resonance region limits). The TCSC module is modeled as a single variable reactance with firing angle (or reactance) limits. Additional limitations can be imposed on the voltage drop and on the line current (in case of line current control).

X TCSC

VMax

Not available

VMax

I Max

X max

X min

Cap. operation

Ind.operation

A

D

CB

E

F

G

ILine

X TCSC

(a): One-module operation (b): Two-module operation

0 ~Xl

Xc



Fig. 4.27 XTCSC versus line current characteristic The figure above depicts the steady-state TCSC equivalent reactance XTCSC versus line current characteristic, where the following physical and operating limitations are displayed:

• A,D: resonance region limitation • B: firing angle limitation (=180°) (XTCSC is equal to the capacitors

reactance Xc) • C: firing angle limitation (=90°) (XTCSC is almost equal to the inductors

reactance Xl) • E,F: upper voltage limits for capacitive and inductive operation • G: maximum allowed current in continuous operation

A TCSC can either operate in the capacitive or in the inductive region. That means, that Xmin and Xmax, must be entered both as negative (Cap. operation) or both as positive (Ind. operation) values. As shown in 4.26a in case of one-module operation there is a range of values for XTCSC that cannot be controlled. Figure 4.26b depicts the same characteristic with two identical modules connected in series with half the rating (half the Xl and Xc reactances) of the original (one) module. The two modules are independently controlled. The control gap is now partially covered and for increasing number of modules the operating area of the TCSC covers the entire region enclosed by the dashed curve in Figure 4.26b. Remark In general (in multi-module operation) each module can have a different firing angle. Therefore in the results there is no firing angle value (firing angle = 0), whereas there is a value for the total effective reactance and voltage drop.



UPFC

This chapter describes the parameters of the Data Input Dialog of a UPFC (Unified Power Flow Controller) and the corresponding UPFC model.

UPFC-Parameters

Name Name of element. Vser min LMDR Minimum series voltage magnitude in % of the bus

nominal voltage. Vser max LMDR Maximum series voltage magnitude in % of the bus

nominal voltage. Iq min LMDR Minimum shunt current in A. Iq max LMDR Maximum shunt current in A. P max LMDR Maximum power through the DC link (Px) in MW. Connecting Transformers Leakage Impedances Series Tr. R LMDR Leakage resistance of series transformer in Ohm. Series Tr. X LMDR Leakage reactance of series transformer in Ohm. Shunt Tr. R LMDR Leakage resistance of shunt transformer in Ohm. Shunt Tr. X LMDR Leakage reactance of shunt transformer in Ohm. Line Flow Regulation at port 2 P LMDR Control value for the active line flow P2. Q LMDR Control value for the reactive line flow Q2. Voltage Regulation Sending end V set

LMDR Control value for the voltage magnitude of the sending end.

Receiv. end V min

LMDR Minimum voltage magnitude at the receiving end.

Receiv. end V max

LMDR Maximum voltage magnitude at the receiving end.

UPFC-Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.



UPFC-Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

UPFC-User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

UPFC-More… Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6.

Description of the Model (UPFC)

Shunt connected converter

Series connected converter

ILine - UT +

IQ

U1 U2

Px (+) P2,Q2

Fig. 4.28 Unified Power Flow Controller (UPFC) The basic structure of the UPFC implementation is shown in the figure above. UPFC consists of two voltage-sourced converters, one connected in shunt with the line through a transformer and one connected in series with the line through a second transformer. The two converters are operated from a common DC link, provided by a DC storage capacitor. The series connected converter injects a controlled voltage UT in series with the line. The phase



angle of the phasor UT can be chosen independently of the line current and the magnitude is variable between zero and a maximum UTmax. The series converter exchanges real and reactive power with the transmission system. The reactive power can be generated independently from the series converter, while the real power has to be supplied from the network. That is the primary function of the shunt converter, which is controlled in such a way as to provide at its DC terminal the real power needed by the series converter. A secondary function of the shunt converter is to generate or absorb reactive power for regulation of the AC terminal voltage U1. Apparent power exchanged through series injected voltage: Sxser = Pxser + jQxser = UT (ILine)* (1) Apparent power exchanged through shunt current: Sxshu = Pxshu + jQxshu = U1 (IQ)* (2) In (1): Pxser > 0 (Qxser > 0) means that active (reactive) power is injected to the system. In (2): Pxshu > 0 (Qxshu > 0) means that active (reactive) power is drawn from the system. The UPFC model ignores device losses, therefore: Pxshu = Pxser = Px The reactive powers Qxser, Qxshu however can be independently produced by the two converters. With nonzero transformer impedances the equations (1) and (2) become:

Apparent power exchanged through series injected voltage: Sxser = Pxser + jQxser = √3 UT (ILine)* (1)

Apparent power exchanged through shunt current: Sxshu = Pxshu + jQxshu = √3 U1 (IQ)* - 3 |IQ|2 (Rshu +jXshu) (2)



Network Feeder

This chapter describes the parameters of the Data Input Dialog of a network feeder and the corresponding network feeder model.

Network Feeder-Parameters

Name Name of element. Type Applicable only with a network feeder library. Pressing

the button "", the type may be chosen and the data can be transferred from the predefined library.

Sk" max, min SMHP Maximum and minimum initial symmetrical short circuit power in MVA (Sk" =√3·Un·Ik").

Ik" max, min SMHP Maximum and minimum initial symmetrical short circuit currents in kA (Ik" = Sk"/(√3·Un)).

R(1)/X(1) max, min

SMHP Maximum and minimum ratio of positive sequence resistance of feeder to its positive sequence reactance.

Z(0)/Z(1) max, min

SP Maximum and minimum ratio of zero sequence impedance to its positive sequence impedance.

R(0)/X(0) max, min

SP Maximum and minimum ratio of zero sequence resistance of feeder to its zero sequence reactance.

C H Capacitance of network in µF. Operational data LF-Type LMDR Node type for load flow calculation. Possible values

are: • "SL": Slack node. Input of values "U oper" and

"Uw oper" compulsory (see below). • "PQ":P,Q-node. Input of values "P" and "Q"

compulsory (see below). U oper LMDR It's the voltage, in % with respect to Un, which the

Slack has to regulate, if the LF-Type will be "SL". Uw oper LMDR Angle of voltage in degrees, if the LF-Type will be "SL". Slack portion LMDR The portion in % of the total slack active power, which

has to be supplied by this network feeder. This value is only considered, if the load flow is calculated with distributed slack or with zone/area control (see load flow calculation parameters). The sum of all slack portions in the network or zone/area may be unequal to 100%. In this case the program internally scales the



slack portion proportionally, so that the effective sum is 100%.

P LMDR Input of active power in MW, if the LF-Type will be "PQ". For generating power the value for P must be given as positive value. For loads the value must be given as negative value.

Q LMDR Input of reactive power in Mvar, if the LF-Type will be "PQ". Positive value means generation of inductive reactive power (over excited generator); negative value means consumption of inductive reactive power (under excited generator).

Network Feeder-Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Network Feeder-Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Network Feeder-User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

Network Feeder-More… Frequency dependence… By pressing this button of the More tab, the Frequency dependence input parameters can be entered. They are only used for harmonic analysis. The description can be found in Frequency dependence of chapter Data Input Dialogs of Network Elements-Element - More on page 4-4. Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description



can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6.

Description of the Model (Network Feeder) The following figure shows the model of a network feeder.

R

X

R

XC

Fig. 4.29 Model of a network feeder for short circuit calculation (above) and for harmonic analysis (below) The model parameters of the positive and zero sequence are calculated as follows: Positive sequence Zero sequence

Z(1) = c·Un²/Sk" δ = arctan(X(1)/R(1)) R(1) = Z(1)·cos(δ) X(1) = Z(1)·sin(δ)

Z(0) = Z(1)· (Z(0)/Z(1)) δ0 = arctan(X(0)/R(0)) R(0) = Z(0)·cos(δ0) X(0) = Z(0)·sin(δ0)

Z(1) = R(1) + j·X(1) Z(0) = R(0) + j·X(0)

For harmonic analysis only the positive sequence is considered and the imped-ance Z(1) will be calculated as a mean value of the minimal and maximal short circuit power.



Synchronous Machine

This chapter describes the parameters of the Data Input Dialog of a synchronous machine and the corresponding model.

Synchronous Machine - Parameters

Name Name of element. Type Applicable only with a synchronous machine library.


Ur SMHPD Rated voltage in kV. pUr SP If the generator voltage Ug is permanently higher than

the rated voltage Ur, this should be indicated with a deviation in %. Only necessary for Short Circuit calculation by IEC60909 (2001).

Sr SMHPD Rated power in MVA. Cos(phi) SMP Power factor. Ufmax/Ufr SP Ratio of highest possible excitation-voltage to rated

excitation at rated load and power factor. xd sat. SP Synchronous reactance in % with respect to Sr and Ur

(saturated value). Recommended value: Turbo-SM: 120 .. 270 Salient pole-SM: 70 .. 130

xd' sat SMHP Saturated transient reactance in % with respect to Sr and Ur. This value will only be used for short circuit calculations according to ANSI. Recommended value: Turbo-SM: (1.4 .. 1.7)* xd" Salient pole with amortisseur winding: 20 .. 45%

xd" sat SMHP Saturated subtransient reactance in % with respect to Sr and Ur. Recommended value: Turbo-SM: 9 .. 22 (large values when large Sr) Salient pole-SM: 12 .. 30 (large values if slow speed rotor with large Sr)

Ikk SP Steady state short circuit current in kA of generator with compound excitation during 3-phase short circuit.

• Ikk=0: Generator with no compound excitation. • Ikk<>0: Generator with compound excitation.



Ikk will be used to calculate the minimum steady state short circuit current for generators with compound excitation.

Mue SP The factor mue will be used for the calculation of breaking currents.

• mue=0 : mue value will be calculated according to IEC standard.

• Mue<>0: mue will be set to the input value. RG SMHP Equivalent resistance of generator in Ohm. RG is

considered for the calculation of all currents except for the calculation of the peak current ip. For ip-calculation a fictive value according to IEC will be taken, no matter which calculation method is used (see Description of the Model (SC)).This fictive value for RG is also used for the calculation, if RG is set to 0.

X(2) SP Negative sequence reactance given by x(2)=0.5(xd"+xq") in % with respect to Sr and Ur. Recommended value: x(2) = xd".

X(0) SP Zero sequence reactance of the synchronous machine in % with respect to Sr and Ur. Recommended value: x(0) = (0.4 .. 0.8) xd".

Amortisseur winding

SP Checkbox, indicates if the synchronous machine has an amortisseur (damper) winding or not.

Motor SP Indicates, if the synchronous machine works as motor. This input influences the minimum short circuit current according to IEC909.

Rotor type SP Indicates the type of the synchronous machine (salient pole or round rotor).

Unit generator

SP Checkbox, indicates whether the machine is part of a power station unit.

Earthing SP Indicates de type of earthing of the generator. Re, Xe SP For impedance earthing: Generator star point earthing

resistance and reactance in Ohm. Active SP The user can define, which portion in % of the earthing

impedance is active. Generation costs

L For the OPF-Simulation it's possible to minimize the generation costs. These costs are represented by the following quadratic curve: C(P) = a*P2 + b*P + c The following parameters have to be entered:



• a: quadric factor in unit of currency (e.g. US$) to MW2

• b: linear factor in unit of currency to MW2 • c: constant factor in unit of currency • P is the active power produced by the generator in

MW

Synchronous Machine - Limits

Name Name of element. P min LDR Minimum allowable active power in MW.

If the synchronous machine works as generator, P min is a positive value and means the minimum amount of active power, which the machine must produce. If the synchronous machine works as motor, P min is a negative value and means the maximum amount of active power, which the machine can consume (see below).

P max LDR Maximum allowable active power in MW. If the synchronous machine works as generator, P max is a positive value and means the maximum amount of active power, which the machine can produce. If the synchronous machine works as motor, P max is a negative value and means the minimum amount of active power, which the machine must consume (see below).

Q min LDR Minimum allowable limit for the reactive power Q in Mvar, when LF-Type equal "PV". If Q runs below this value during LF-calculation, Q will be set Q = Q min (only for Newton-Raphson method). If the synchronous machine works over excited, Qmin is a positive value and means the minimum amount of inductive reactive power, which the machine must produce. If the synchronous machine works under excited, Qmin is a negative value and means the maximum amount of inductive reactive power, which the



machine can consume. Q max LDR Maximum allowable limit for the reactive power Q in

Mvar, when LF-Type equal "PV". If Q runs beyond this value during LF-calculation, Q will be set Q = Q max (only for Newton-Raphson method). If the synchronous machine works over excited, Q max is a positive value and means the maximum amount of inductive reactive power, which the machine can produce. If the synchronous machine works under excited, Q max is a negative value and means the minimum amount of inductive reactive power, which the machine must consume.

Cosphi control P lim LDR Break point of the characteristic curve. Cosphi max LDR Maximum Cosphi of the feasible domain of "Cosphi

oper". The check box "Capacitive" selects between inductive or capacitive operation.

Cosphi min LDR Minimum Cosphi of the feasible domain of "Cosphi oper". The check box "Capacitive" selects between inductive or capacitive operation.

Capability Curve Curve LDR The user can define himself a PQ-curve. Depending on

the active power P, the limits Qmin and Qmax of the reactive power will be defined by this Capability Curve for a LF-type PV. Points of this curve may be entered with "Insert", and removed with "Delete". The whole (Pmin, Pmax) range must be included in the capability list.

Active during calculation

LDR During LF-calculation the PV-generator is checking if the necessary reactive power Q, to guarantee the node-voltage U oper, is between Qmin and Qmax. If the Capability Curve is active, the program is using the limits defined in this curve.

Synchronous Machine - Operational

Name Name of element. LF-Type LDR Type of node for load flow calculation.

Possible values:



• "PQ": P,Q-node. Input of the values "P" and "Q" compulsory (see below).

• "PV": P,V-node. Input of the values "U oper" and "P" compulsory (see below).

• "SL": Slacknode. Input of the value "U oper" compulsory (see below). Voltage angle will be set to 0.

• "PC": P,C-node. Input of the values "P" and "Cosphi oper" compulsory (see below).

Operating Mode

() Based on the operational data, the operating mode indicates if the synchronous machine is working as a generator or as a motor and if it is over- or underexcited.

U oper LD Amount of voltage in % related to Un, if LF-Type equal "PV" or "SL". The generator will be voltage-regulated.

Uw oper LMDR Angle of voltage in degrees, if the LF-Type will be "SL". PGen LMDR Input of active power in MW, if the LF-Type will be

"PV", "PQ", or "PC". For generating power the value for P must be given as positive value. For loads the value must be given as negative value. This value will be multiplied by the scaling factor to receive the operational power Poper.

QGen LMDR Input of reactive power in Mvar, if the LF-Type will be "PQ". Positive value means generation of capacitive reactive power (overexcited generator); negative value means consumption of capacitive reactive power (underexcited generator). This value will be multiplied by the scaling factor to receive the operational power Qoper.

Effective scaling factor for P

LMDR Indicates the total scaling factor for the active power of the synchronous machine. It is calculated by the product of the network, of the zone and of the assigned scaling factor for P: fep=fnp*fzp*fap

Effective scaling factor for Q

LMDR Indicates the total scaling factor for the reactive power of the synchronous machine. It is calculated by the product of the network, of the zone and of the assigned scaling factor for Q: feq=fnq*fzq*faq

Scaled values LMDR For PV, PQ and PC LF-types, the effective active power P, to be produced or consumed, is indicated. For PQ LF-typ, additionally the effective reactive power Q, to be produced or consumed, is indicated.



The scaled values Poper and Qoper are calculated with P and Q and the respective scaling factors: Poper= P* fep ; Qoper= Q* feq

Remote controlled bus

LDR In case of a voltage regulated generator (LF-Type: PV) the node to be regulated can be entered here. If this input field is empty, the voltage of the generator node will be regulated. The remote control is only working for nodes, which are connected with the generator node through elements. In case of a three-windings transformer remote control is only possible for a generator connected at the secondary node. The tertiary node must have no load and no generation (I3 = 0.0 A)

Static LDR The static in Hz/MW of the generator can be entered here. The static S is defined as follows: Static: S = -(f0 f) / (Poper P) Poper: Scaled value for active power P: Calculated active power for operating frequency f f0: Nominal system frequency in Hz. f: Operating frequency in Hz. The calculated active power at operating frequency f is P = P0 + (f0 f) / S. The operating frequency f can be entered in the load flow calculation parameters.

Slack portion LDR The portion in % of the slack active power, which has to be generated or consumed by this synchronous machine. This value is only considered, if the load flow is calculated with distributed slack or with area interchange control (see load flow calculation parameters). The sum of all slack portions in the network or zone/area may be unequal to 100%. In this case the program internally scales the slack portion proportionally, so that the effective sum is 100%.

Qpv LDR The portion of reactive power in %, which has to be generated or consumed by this machine in case of PV-node (with or without remote control) in case of different machines regulating the voltage of the same node (see below). The sum of all Qpv portions for the regulated node may be unequal to 100%. In this case the program internally scales the Qpv portion proportionally, so that the effective sum is 100%.



Cosphi control (LF type "PC") Cosphi oper LDR Cosphi-value of the generator, used for the following

"Cosphi control" options: • Cosphi oper remains constant for the option

"Cos(phi) constant". • Cosphi oper is used as initial value for the

options "Reactive power" and "Reactive/active power".

Capacitive LDR The check box "Capacitive" selects between inductive or capacitive operation.

Cos(phi) constant

LDR The control input "Cosphi oper" is constant.

Cos(phi) characteristic curve

LDR "Cosphi oper" changes dependent on the active power according to a characteristic curve (see Cosphi characteristic curve).

Reactive power

LDR If the corresponding node voltage becomes greater than its maximum value U max, "Cosphi oper" changes so, that the asynchronous machine is lowering the reactive power production, respectively increasing the consumption of inductive reactive power. "Cosphi oper" must not leave the feasible domain defined by "Cosphi min" and "Cosphi max".

Reactive/ active power

LDR Same behavior as type "Reactive Power". If "Cosphi oper" can't be adjusted further, the active power is reduced so that the node voltage doesn't exceed Umax.

Synchronous Machine – Scaling Factors

Operating Mode

LMDR Indicates if the synchronous machine is working as a generator or motor, depending on the sign of the active power P. For the generator mode, P has to be positive, for motor mode negative.

Scaling factor of network

LMDR Displays the predefined scaling factor of P and Q for the network. Depending on the Operating Mode, these are the scaling factors for generation or load. Predefined scaling factors may be changed in Edit - Data - Operational Data (see chapter Menu Options).

Scaling factor of zone

LMDR Displays the predefined scaling factors of P and Q for the zone. Depending on the Operating Mode, these are the scaling factors for generation or load. Predefined



scaling factors may be changed in "Edit - Data - Operational Data" (see chapter Menu Options).

Assigned scaling factor

LMDR Displays the scaling factors of P and Q, assigned to this synchronous machine. It's a total of the assigned user defined scaling factors (see below).

Effective scaling factor

LMDR Displays the effective scaling factors of P and Q for this synchronous machine. It's the product of all scaling factors: fe=fn*fz*fa

Assign user defined scaling factors Table LMDR The user has the possibility to assign one or more user

defined scaling factors. Every user defined scaling factor may consist of a constant factor (P-factor, Q-factor) and a time dependent factor (characteristics). If there are various user defined scaling factors in the table, a total factor has to be calculated with help of the portion. The portion may be defined directly in the table and it has to be considered that the total of all portions cant exceed 100%. That's why it's necessary to lower first a portion before increasing an other one. The total of all assigned user defined scaling factors is displayed in the fields "Assigned scaling factor and its calculated as follows: faP= p1 * Pfactor1 + p2 * Pfactor2 + faQ= p1 * Qfactor1 + p2 * Qfactor2 + p = Portion For simulations with the module Load Flow with Load Profiles the time dependent scaling factor gets into the equation: faP= p1 * Pfactor1 * Pfactor_t1(t) + p2 * Pfactor2 * Pfactor_t2(t) + faQ= p1 * Qfactor1 * Qfactor_t1(t) + p2 * Qfactor2 * Qfactor_t2(t) +

Insert LMDR Inserts in the table a time dependent scaling factor, which can be chosen from a list of all defined factors.

Remove LMDR Removes the marked scaling factor from the table. Define scaling factors

LMDR Enters in the Scaling Factors Editor, where the user may define Scaling Factors and the time-dependent characteristic curves (see chapter User Defined Scaling Factors on page 4-151).

Show characteristic

LMDR Shows the time dependent characteristic curves of the Scaling Factor Type marked in the table.



Synchronous Machine – Dynamic

Name Name of element. Ur SMHPD Rated voltage in kV. Sr SMHPD Rated power in MVA. Model D Indicates the model of the synchronous machine for

dynamic simulation. Possible models are: - Classical - Transient - Subtransient

Rotor type D Indicates the rotor type of the synchronous machine. H D Inertia constant of the generator and turbine. D D Mechanical damping in MW/Hz. R D Stator resistance Machine reactances Xd D d-axis synchronous reactance in % with respect to Sr

and Ur. Xq D q-axis synchronous reactance in % with respect to Sr

and Ur. Xd' D d-axis transient reactance (unsaturated) in % with

respect to Sr and Ur. Xq' D q-axis transient reactance (unsaturated) in % with

respect to Sr and Ur. Xd" D d-axis subtransient reactance (unsaturated) in % with

respect to Sr and Ur. Xq" D q-axis subtransient reactance (unsaturated) in % with

respect to Sr and Ur. Xc D Characteristic reactance in % with respect to Sr and Ur.

This value is used to calculate the field values. If Xc is unknown, set Xc = Xp.

Xl D Stator leakage reactance or Potier reactance in % with respect to Sr and Ur.

Time constants Type D Indicates, if the time constants are entered for open

circuit or short circuit. The corresponding values are calculated.



Tdo' D d-axis transient open-circuit time constant in s. Tqo' D q-axis transient open-circuit time constant in s. Tdo" D d-axis subtransient open-circuit time constant in s. Tqo" D q-axis subtransient open-circuit time constant in s. Td' D d-axis transient short-circuit time constant in s. Tq' D q-axis transient short-circuit time constant in s. Td" D d-axis subtransient short-circuit time constant in s. Tq" D q-axis subtransient short-circuit time constant in s.

For salient pole machines qq x'x = and/or 0'Tq0 = must be set.

Synchronous Machine – Saturation (D) Saturation parameters may be inserted for d-axis and q-axis. Saturation D Indicates if the saturation is considered for the

calculation. Type D Indicates, if the saturation will be described with the

field currents Ia, Ib, Ic or the parameters A and B (see below). The value for Ia must always be entered. Possible values are: - Field currents Ia, Ib, Ic - Parameter A, B The corresponding values are calculated.

Ia D Exciter current in A on the air gap characteristic at nominal voltage. This value must always be entered, even if the saturation is described by the parameters A and B.

Ib D Exciter current in A on the open-circuit characteristic at nominal voltage (see below).

Ic D Exciter current in A on the open-circuit characteristic at 120% of nominal voltage (see below).

A, B D Parameter values or saturation factors (see below). The saturation of a synchronous machine is defined by its open-circuit characteristic. The graph will be described with the parameters Ia, Ib and Ic of the air gap and the open-circuit characteristic:



air gap characteristic

open-circuit characteristic

terminal voltage

120 %

100 %

field current I a I b I c

0 %

0

Fig. 4.30 Air gap and open circuit characteristic With these currents Ia, Ib and Ic, the saturation factors A and B can be calculated, which are used to reproduce the open-circuit characteristic approximately.

( )( )8.01 −− ⋅+•= uB

AirgapcircuitOpen eAII

with ( )( )aca

ab

I.IIIIA

⋅−⋅−

=21

2

and ( )

−⋅⋅−

•=ab

ac

II.I.IlnB

21215

Synchronous Machine – Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Synchronous Machine - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Synchronous Machine - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Synchronous Machine - More… Frequency dependence… By pressing this button of the More tab, the Frequency dependence input parameters can be entered. They are only used for harmonic analysis. The description can be found in Frequency dependence of chapter Data Input Dialogs of Network Elements-Element - More on page 4-4. Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6.

Portions of Reactive Power for PV-Generators The sum of the Q portions for one PV-node doesnt need to be 100%. The program calculates proportionally the effective portion factor.

Q pv = 50% ! (50*100/120=41.7%)

Q pv = 30% ! (30*100/120=25%)

Q pv = 40% ! (40*100/120=33.3%)

PV-Node

G

G

G

Q pv = 50% ! (50*100/120=41.7%)

Q pv = 30% ! (30*100/120=25%)

Q pv = 40% ! (40*100/120=33.3%)

PV-Node, Remote control

G

G

G



P- and Q-limits of the Machine The limits must be entered as follows:

0

P min P max

Motor Generator

0

Q min Q max

Under excited Over excited

Cosphi characteristic curve (SM)

Cosphi min

Cosphi max

P max P min P lim

Cosphi oper

P

Fig. 4.31 Cosphi characteristic curve

Description of the Model (SC) (SM)

R

X



Fig. 4.32 Model of a synchronous machine for short-circuit calculation The model parameters of the positive, negative and zero sequence are calculated as follows: Positive sequence Negative sequence R = Rf R = Rf X = xd"·Ur²/(100·Sr) X = x(2)·Ur²/(100·Sr)

Zero sequence R = Rf + 3·RE X(0) = x(0)·Ur²/(100·Sr) X = X(0) + 3·XE

The parameter RG (resistance) is set in function of Ur and Sr according to IEC (RG of the Data Input Dialog is used only for the calculation of iDC and only if RG is unequal to 0): Rf = 0.05·Xd" (for Ur > 1 kV and Sr >= 100 MVA) Rf = 0.07·Xd" (for Ur > 1 kV and Sr < 100 MVA) Rf = 0.15·Xd" (for Ur <= 1 kV)

Remarks: According to IEC the impedance Z =R+j·X will be multiplied by the factor K: IEC909 (1988) If Generator is a part of a power station unit:

rxdcK

ϕsin1 "max

⋅+=

IEC60909 If short circuit is fed directly from the generator without transformer:

( ) rrGr

n

xdc

pUUU

Kϕsin11 "

max

⋅+⋅

+⋅=

If the generator is a part of a power station unit with on-load tapchanger:

rGTrTHV

rTLV

rG

n

xxdc

UU

UU

Kϕsin1 "

max2

2

2

2

⋅−+⋅⋅=

If the generator is a part of a power station unit without on-load tapchanger:



( ) ( )rG

TrTHV

rTLV

rGrG

n

xdc

pUU

pUUU

Kϕsin1

11 "

max

⋅+⋅±⋅⋅

+⋅=

When the minimal short circuit current is calculated the reactance of all compound excited generators (Ikk≠0) are set to Xdk=Ur/(√3·Ikk). The parameters Ufmax/Ufr, xd sat. and "Rotor type" are needed to calculate the gamma value resp. the steady state current IrIk ⋅= λ . Ir stands for the rated current. The breaking current will be calculated as Ia = µ · Ik". The factor µ is defined as a function of minimum delay of circuit breakers tmin (parameter is given in the calculation parameter mask of module Short circuit) and of the ratio Ik"/Ir. The factor µ will not be calculated when a value unequal 0 is given in the corresponding input field (only in special cases, see IEC standard / 2 /).

Time constants The following relations are valid for the time constants: Td0' + Td0" = xd/xd' * Td' + (1 - xd/xd' + xd/xd") * Td" Td0' * Td0" = xd/xd" * Td' * Td" and Tq0' + Tq0" = xq/xq' * Tq' + (1 - xq/xq' + xq/xq") * Tq" Tq0' * Tq0" = xq/xq" * Tq' * Tq"

Description of the Dynamic Models There are three models available for dynamic simulations of synchronous machines: (1) Classical model (2) Transient model (3) Sub-transient model The suitable model to select is determined by the existing data or by the machine's importance for a particular fault event. The larger the synchronous machine in question and the closer it is in electrical terms to the fault computed, the higher must be the precision of the machine model selected. For machines farther away or less important, simpler models can be selected.



Classical model A classical model is built as a constant voltage source behind a constant impedance, z.

zue

i k

Fig. 4.33 Classical model for dynamic analysis The magnitude and angle of the complex voltage, e are constant. The impedance z is

'jxrz da +=

For xd the saturated value will be used. The saturated value of xd may also be calculated in Prost from the unsaturated value (see Synchronous Machine Saturation (D) on page 4-104). The angle delta of the voltage e is determined from the swing equation (in per unit)

em0

D2

2

0mm

dtd

ωK

dtd

ωH2 −=δ⋅+δ⋅⋅

⋅= *ie Realme

The mechanical torque mm may be determined through a speed governing system. Inertia constant H can be calculated from moment of inertia GD2.

]kVA[N

]tm[22

]min[]s[ S

GD60

n

21=H

21⋅

⋅π⋅

−

Data required for classical model:

Sn Nominal complex power Un Nominal voltage



ra Stator resistance xd' Direct axis transient reactance H Inertia constant KD Damping constant

Transient model The transient model is a simple model in which, in addition to the swing equation (See classical model) transient effects of direct and quadrature axes are also considered. The field voltage Ufd may be modified through an automatic voltage regulator. The circuit corresponds to that of subtransient model without subtransient windings.

'sT1

Uix'xi'xψ

ψiru

d0

fddddddd

qdad

+

+⋅−+⋅−=

−⋅−=

'sT1

ix'xi'xψ

ψiru

q0

qqqqqq

dqaq

+

⋅−+⋅−=

+⋅−=

dqqde iψiψm ⋅−⋅=

The saturation of the main magnetic field is taken into consideration through saturated reactances. They can be entered directly in the Params tab of the data input dialog, or the program can calculate them for an initial operating point with the saturation curves and the unsaturated reactances in the Params tab (see Synchronous Machine Saturation (D) on page 4-104). Saturated reactances remain constant during the simulation. Data required for transient model:

Sn Nominal complex power Un Nominal voltage ra Stator resistance xl Stator leakage reactance xd Direct axis synchronous reactance xd' Direct axis transient reactance Td0 Direct axis transient open circuit time constant xq Quadrature axis synchronous reactance xq Quadrature axis transient reactance



Tq0 Quadrature axis transient open circuit time constant H Inertia constant KD Damping constant


Subtransient model The subtransient model represents a complete machine model as given in the following circuits.

xl xrc rfd xfd

x1d

r1d

xad

i1d

ifd id

ud ufd

-id+ifd+i1d

R=ra

xl

x1q

r1q

xaq

i1q

iq

uq x2q

r2q

i2q -iq+i1q+i2q

R=ra

Fig. 4.34 Subtransient model for dynamic analysis Simpler models can be simulated by setting some of these characteristic values to zero. xad, xfd, rfd and xaq are not allowed to be zero. The saturation of the main field is represented by saturated reactances xads and xaqs. During the simulation these reactances are modified according to the actual main field. The per unit equations of the subtransient model is as follows:



aqqldad ψixiru −⋅+⋅−= addlqaq ψixiru +⋅−⋅−=

( )

⋅++⋅⋅+⋅+−⋅=

1dfd1dfdrc1dfdfd1d

d"adsad xxxxx

ψxψxixψ

++−⋅=

2q

2q

1q

1qqaqsaq x

ψxψ

i"xψ

ad1ad1d11dfd1fd1d

fdffdadfad1df1dfdffdfd

ψbψaψadtdψ

ubψbψaψadtdψ

⋅⋅⋅

⋅⋅⋅⋅

++=

+++=

aq2aq2q22q2q

aq1aq1q11q1q

ψbψadtdψ

ψbψadtdψ

⋅⋅

⋅⋅

+=

+=

daqqade iψiψm ⋅−⋅=

For swing equation see classical model. The q-axis leads the d-axis by 90o. The coefficients of differential equations are calculated from circuit elements. wo is the nominal frequency.

( ) 1dfd1dfdrc1dfd

ads

ads

xxxxxxx

x1

1"x⋅++⋅

++=

2q1qaqs

aqs

x1

x1

x1

1"x++

=



( )( )

( )

( )( )

( )

( )

( )0ffd

1dfd1dfdrc

fd1d01ad

1dfd1dfdrc

1dfd0fad

1dfd1dfdrc

fdrc1d011d

1dfd1dfdrc

rc1d01fd

1dfd1dfdrc

rcfd0f1d

1dfd1dfdrc

1drcfd0ffd

ωbxxxxx

xrωb

xxxxxxrω

b

xxxxx

xxrωa

xxxxxxrω

a

xxxxxxrω

a

xxxxxxxrω

a

=⋅++⋅

⋅⋅=

⋅++⋅⋅⋅

=

⋅++⋅

+⋅⋅−=

⋅++⋅⋅⋅

=

⋅++⋅⋅⋅

=

⋅++⋅+⋅⋅−

=

2q

2q02aq

1q

1q01aq

2q

2q022q

1q

1q011q

xrω

b

xrω

b

xrω

a

xrω

a

⋅=

⋅=

⋅−=

⋅−=

Data required for subtransient model (unsaturated values):

Sn Nominal complex power Un Nominal voltage ra Stator resistance xl Stator leakage reactance xc Characteristic reactance xd Direct axis synchronous reactance xd' Direct axis transient reactance xd Direct axis subtransient reactance Td0 Direct axis transient open circuit time constant Td0 Direct axis subtransient open circuit time constant xq Quadrature axis synchronous reactance xq Quadrature axis transient reactance xq Quadrature axis subtransient reactance Tq0 Quadrature axis transient open circuit time constant Tq0 Quadrature axis subtransient open circuit time constant H Inertia constant KD Damping constant




Characteristic reactance xc: The reactance xc is an additional characteristic variable required for a more accurate calculation of the exciter field variables. It can be determined by measurement, or calculated from design data. For more detailed notes, see [2]. If the value of xc is not known, the stator leakage reactance xl (Potier reactance) is used as a default value.



Asynchronous Machine

This chapter describes the parameters of the Data Input Dialog of an asynchronous machine and the corresponding model.

Asynchronous Machine - Parameters

Name Name of element. Type Applicable only with an asynchronous machine library.


No. of motors

SMHP Number of identical asynchronous motors at the node.

Input Ir SMHP Defines if the current Ir or the Cosphi and the Efficiency can be entered. If the checkbox is active, Ir may be entered and the Efficiency and Sr will be calculated. If the checkbox isn't active, the Cosphi and the Efficiency have to be entered and Sr and Ir will be calculated.

Ur SMHP Rated voltage in kV. Ir SMHP Rated current in kA. Sr SMHP Rated power in MVA. This value is calculated by Ur and

Ir. Pr mech SMHP Rated active power in MW. Rated slip sr

M** Slip at rated operation in %.

Cosphi at Sr and sr

SMHP Power factor cos(phi) at Sr and sr.

Efficiency at Sr and sr

SMHP Efficiency for rated operation.

Pole pairs of stator

SMHP Number of pole pairs of stator.

Ia/Ir SMHP Ratio of locked-rotor current to the rated current of the motor.

Ma/Mr M* Ratio of starting torque to rated torque. Mk/Mr M* Ratio of breakdown torque to rated torque. Cosphi start M* Power factor at start. Transient model

D Type of transient model used for dynamic analysis.



ANSI factor SP ANSI factor. If short circuit is calculated according to ANSI/IEEE, the factor for multiplying the subtransient reactance of the motor can be entered here. The factors are given in section 5.4.1 of the ANSI/IEEE Standard C37.010-1979. Pressing the "Calculate" button, the factor will be set automatically by the program.

Rm SMHP Equivalent resistance of motor in Ohm. If 0, a fictive value according to IEC will be taken (see below).

Converter fed drive

SMHP Indicates if the machine is a converter fed drive.

Asynchronous Machine - Operational

Name Name of element. LF-Type LMDR Defines, how the motor is modeled, when the motor is

not started up: Mload: The motors operating point is calculated with the help of the operating load torque (see chapter "Motor Starting"). The consumed power depends on the load torque and the terminal voltage. The parameters, which are marked with (M*) or (M**), are necessary. PQoper: The motor works with constant power Poper and Qoper. The parameters, which are marked with (M*) or (M**), are not necessary. PC: The motor works with constant power Poper and constant Cosphi oper. A Cosphi control may be activated for this LF-Type.The parameters, which are marked with (M*) or (M**), are not necessary.

Operating mode

() Based on the operational data, the operating mode indicates if the asynchronous machine is working as a motor or as a generator.

P LMDR Active power in MW to be consumed. For supersynchronous operation this value must be entered negative. In normal operation of ASM this value is positive. P can also be calculated from the machine mechanical power Pmech (see below). This value will be multiplied by the scaling factor to receive the operational power Poper.



Q LMDR Reactive power in Mvar of ASM. This value is always positive. Q can also be calculated from the machine mechanical power Pmech and Cosphi (see below). This value will be multiplied by the scaling factor to receive the operational power Qoper.

Effective scaling factor for P

LMDR Indicates the total scaling factor for the active power of the asynchronous machine. It is calculated by the product of the network, of the zone and of the assigned scaling factor for P: fep=fnp*fzp*fap

Effective scaling factor for Q

LMDR Indicates the total scaling factor for the reactive power of the asynchronous machine. It is calculated by the product of the network, of the zone and of the assigned scaling factor for Q: feq=fnq*fzq*faq

Scaled values LMDR The scaled values for Poper and Qoper are calculated with P and Q and the respective scaling factors: Poper= P* fep ; Qoper= Q* feq

Calculate P and Q

LMDR P and Q may be calculated from the efficiency, cos(phi) and Pmech by pressing the button "Calculate". The value for Pmech (Mechanical power of the machine in MW) can be entered here. Otherwise the option has to be chosen, that Pmech is equal to the rated mechanical power Pr mech. Option Pmech: P = Pmech / Efficiency; Q = P*sqrt(1-cos2)/cos Option Pmech=Pr mech: P = Pr mech / Efficiency; Q = P*sqrt(1-cos2)/cos

Cosphi control (LF type "PC") Cosphi oper LDR Cosphi-value of the asynchronous machine, used for

the following "Cosphi control" options: • Cosphi oper remains constant for the option

"Cos(phi) constant". • Cosphi oper is used as initial value for the options

"Reactive power" and "Reactive/active power". Capacitive LDR The check box "Capacitive" selects between inductive

or capacitive operation. Cos(phi) constant

LDR The control input "Cosphi oper" is constant.

Cos(phi) LDR "Cosphi oper" changes dependent on the active power



characteristic curve

according to a characteristic curve (see Cosphi characteristic curve for asynchronous machine).

Reactive power

LDR If the corresponding node voltage becomes greater than its maximum value U max, "Cosphi oper" changes so, that the asynchronous machine is lowering the reactive power production, respectively increasing the consumption of inductive reactive power. "Cosphi oper" must not leave the feasible domain defined by "Cosphi min" and "Cosphi max".

Reactive/ active power

LDR Same behavior as type "Reactive Power". If "Cosphi oper" can't be adjusted further, the active power is reduced so that the node voltage doesn't exceed Umax.

Asynchronous Machine – Scaling Factors

Operating Mode

LMDR Indicates if the asynchronous machine is working as a load or as a generator, depending on the sign of the active power P. For the load mode, P has to be positive, for generator mode negative.


LMDR Displays the predefined scaling factor of P and Q for the network. Depending on the Operating Mode, these are the scaling factors for generation or load. Predefined scaling factors may be changed in Edit - Data - Operational Data (see chapter Menu Options).


LMDR Displays the predefined scaling factors of P and Q for the zone. Depending on the Operating Mode, these are the scaling factors for generation or load. Predefined scaling factors may be changed in Edit - Data - Operational Data (see chapter Menu Options).

Assigned scaling factor

LMDR Displays the scaling factors of P and Q, assigned to this asynchronous machine. It's a total of the assigned user defined scaling factors.

Effective scaling factor

LMDR Displays the effective scaling factors of P and Q for this asynchronous machine. It's the product of all scaling factors: fe=fn*fz*fa

Assign user defined scaling factors Table LMDR The user has the possibility to assign one or more user

defined scaling factors. Every user defined scaling factor may consist of a constant factor (P-factor, Q-factor) and a time dependent factor (characteristics). If



there are various user defined scaling factors in the table, a total factor has to be calculated with help of the portion. The portion may be defined directly in the table and it has to be considered that the total of all portions cant exceed 100%. That's why it's necessary to lower first a portion before increasing an other one. The total of all assigned user defined scaling factors is displayed in the fields "Assigned scaling factor and its calculated as follows: faP= p1 * Pfactor1 + p2 * Pfactor2 + faQ= p1 * Qfactor1 + p2 * Qfactor2 + p = Portion For simulations with the module Load Flow with Load Profiles the time dependent scaling factor gets into the equation: faP= p1 * Pfactor1 * Pfactor_t1(t) + p2 * Pfactor2 * Pfactor_t2(t) + faQ= p1 * Qfactor1 * Qfactor_t1(t) + p2 * Qfactor2 * Qfactor_t2(t) +

Insert LMDR Inserts in the table a time dependent scaling factor, which can be chosen from a list of all defined factors.

Remove LMDR Removes the marked scaling factor from the table. Define scaling factors

LMDR Enters in the Scaling Factors Editor, where the user may define Scaling Factors and the time-dependent characteristic curves (see chapter User Defined Scaling Factors on page 4-151).

Show characte-ristic

LMDR Shows the time dependent characteristic curves of the Scaling Factor Type marked in the table.

Asynchronous Machine - Limits

Name Name of element. LF-Type LMDR Defines, how the motor is modeled, when the motor is not

started up: Mload: The motors operating point is calculated with the help of the operating load torque (see chapter "Motor Starting"). The consumed power depends on the load torque and the terminal voltage. The parameters, which are marked



with (M*) or (M**), are necessary. PQoper: The motor works with constant power Poper and Qoper. The parameters, which are marked with (M*) or (M**), are not necessary. PC: The motor works with constant power Poper and constant Cosphi. A Cosphi control may be activated for this LF-Type.The parameters, which are marked with (M*) or (M**), are not necessary.

P min LDR Minimum allowable active power in MW. If the asynchronous machine works as a load, P min is a positive value and means the minimum amount of active power, which the load will consume. If the asynchronous machine works as a generator, P min is a negative value and means the maximum amount of active power, which the machine can produce.

P max LDR Maximum allowable active power in MW. If the asynchronous machine works as a load, P max is a positive value and means the maximum amount of active power, which the machine can consume. If the asynchronous machine works as a generator, P max is a negative value and means the minimum amount of active power, which the machine must produce.

P lim LDR Break point of the characteristic curve. Cosphi max LDR Maximum Cosphi of the feasible domain of "Cosphi

oper". The check box "Capacitive" selects between inductive or capacitive operation.

Cosphi min LDR Minimum Cosphi of the feasible domain of "Cosphi oper". The check box "Capacitive" selects between inductive or capacitive operation.

Asynchronous Machine – Model The date entered in the Model tab is only used for motor starting calculations. For more information about the motor starting calculation please see the respective chapter.



There are two possibilities how to calculate the model of the asynchronous machine for motor starting. The first is a simplified manner, because the rotor resistance R2(s) and the leakage reactance X2(s) are calculated for s=1 and s=sr and then they are linearly interpolated between the two points. An other possibility is to enter predefined curves for M/Mr and I/Ir as precise as possible (curves given by the manufacturer). Using the entered values, R2 and X2 may be calculated for every point. Between the entered points, R2 and X2 will be interpolated linearly. Using these exact curves of R2 and X2 for the model of the asynchronous machine, the electromagnetic torque Me and the current I may be calculated for every possible slip s. Thats why the input of data in this Model tab is only necessary for the second, more precise possibility of calculating the model. The first possibility is standard and is done automatically. Equivalent-circuit impedances R1/Zr M Stator side resistance related to Zr. X1/Zr M Stator side leakage reactance related to Zr. Xh/Zr M Main reactance related to Zr. Rated values Ur SMHP Rated voltage in kV, entered in the Params tab. Ir SMHP Rated current in kA, entered in the Params tab. Mr M Rated torque in Nm. Zr M Rated impedance in Ohm, calculated with Ur and Ir. Asynchronous machine table entries Insert A new table line will be entered. Delete The marked table lines will be deleted. Calculate M By pressing the button, R2/Zr and X2/Zr will be

calculated for every slip which has the Calc. R2, X2 box checked. Using m/Mr and I/Ir.

Sort The table entries will be sorted according to the slip. Plot Predefined (based on M/Mr and I/Ir) and calculated

(based on X2/Zr(s) and R2/Zr(s)) curves for the current I(s), the electromagnetic torque Me(s), the Cosphi(s) and the load torque Ml(s) may be displayed.

S M Slip M/Mr M Electromagnetic torque related to rated torque. I/Ir M Current related to rated current. Cosphi Cos(phi), not necessary for the calculation of R2/Zr



and X2/Zr. R2/Zr M Rotor resistance related to Zr X2/Zr M Leakage reactance related to Zr Calc. R2,X2 M Checkbox, defines if R2 and X2 shall be calculated

when the button Calculate is pressed. Library Characteristic type

M The table entries (machine characteristic) can be imported from or exported to a library. By pressing the button , an existing characteristic type in the selected library can be chosen.

Export to library

M The table entries (machine characteristic) may be exported to the library by pressing this button. A name for the characteristic has to be typed in the text field.

Equivalent circuit for motor starting calculations The equivalent circuit of an asynchronous machine for motor starting calculation is given below:

R2(s)/s

X2(s)

Xh

R1 X1

Fig. 4.35 Asynchronous machine equivalent circuit The equivalent circuit impedances are calculated with the help of the input values of the Params tab: X1 = k·(Ir/Ia) 0.26 < k < 0.55, default k=0.5;

Xh = 1.0 / (sin(ϕ) - cos(ϕ) · ((Mk/Mr) - √((Mk/Mr) 2 - 1.0)) R1 = ha - (Ir/Ia)2·(Ma/Mr) · η · cos(ϕ) / (1.0 - sr) R2(s=1) = Xh2·(ha - R1) / hb X2(s=1) = Xh · hc / hb R2(s=sr) = Xh2 · (cos(ϕ) - R1) · sr / hd X2(s=sr) = Xh · ((X1 - sin(ϕ)) · (sin(ϕ) - X1 - Xh) - (R1 - cos(ϕ)) 2 / hd



ha = (Ir/Ia) · cos(ϕan)

hb = (ha - R1) 2 + ((Ir/Ia) · sin(ϕan) - X1 - Xh) 2 hc = (X1 - (Ir/Ia) · sin(ϕst)) · ((Ir/Ia) · sin(ϕst) - X1 - Xh) - (R1 - (Ir/Ia) · cos(ϕst)) 2 hd = (cos(ϕ) - R1) 2 + (sin(ϕ) - X1 - Xh) 2

The following abbreviations are taken: Cos(ϕ): Rated power factor

Cos(ϕst): Locked rotor power factor Mr, Mk, Ma: Nominal, breakdown and locked rotor torque Ir, Ia: Rated and locked rotor current η: Efficiency s, sr: Slip and rated slip

Consideration of Saturation and eddy currents The saturation of the leakage reactance X2 and the eddy-currents losses in R2 are considered in the equivalent circuit as follows: Without any table entries in the Model tab: During start-up the resistance R2 and the reactance X2 are linear interpolated between the points R2(s=1) and R2(s=sr) resp. X2(s=1) and X2(s=sr). The calculation of these values from the motors input values are given above. This representation of the motor leads to a result on the safer side. With table entries in the Model tab: To obtain more accurate results, the user has the possibility to enter a sequence of rotor resistances and leakage reactances R2 resp. X2 in function of the slip s. Because it is difficult to know the values for R2 and X2 in functions of the slip, the user can enter the values for the electromagnetic torque Me, the current I and the Cos(phi) in function of the slip (curves given by the manufacturer -> predefined curves). With these values the program calculates R2 and X2 for each given slip, when the Calculate button has been pressed. For every slip between the given values, the program interpolates linearly R2 and X2, to get a complete model. To compare the calculated curves with the manufacturers (predefined) curves, it is possible to display both in the same diagram (button Calculate).



Asynchronous Machine – Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Asynchronous Machine - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Asynchronous Machine - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

Asynchronous Machine - More… Frequency dependence… By pressing this button of the More tab, the Frequency dependence input parameters can be entered. They are only used for harmonic analysis. The description can be found in Frequency dependence of chapter Data Input Dialogs of Network Elements-Element - More on page 4-4. Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6. Start-up device

Start-up M** Indicates, whether the machine will be started up during motor starting calculation or not.

t start M** Time in seconds after which the motor will be start-up. Start-up device

M** Starting device. Possible values: - Direct: Direct start-up - YD: Wye-Delta start-up - Z stator: Start-up impedance - R rotor: Rotor resistance start-up



- Transformer: Start-up with auto-transformer - C: Start-up with compensation

t switch, s switch

M** There are two options to by-pass the start-up device. It can be switched after reaching a certain time or a certain slip in %. When switching after time, the delay of start-up tstart will be considered. The switching time will be therefore t = tstart + tswitch. If direct starting this value has no meaning.

Transfomer Ur1, Ur2 M** Transfomer rated voltage at primary and secondary side

in kV. This input is only relevant in case of transformer start-up.

Sr M** Transfomer rated power in MVA. This input is only relevant in case of transformer start-up.

uRr, ukr M** Transformer copper losses and short circuit voltage in % This input is only relevant in case of transformer start-up.

Z stator Rs M** Real part of stator start-up impedance in Ohm. This input

field is only important if the start-up device will be "Z stator".

Xs M** Imaginary part of stator start-up impedance in Ohm. This input field is only important if the start-up device will be "Z stator".

R rotor Rr M** Start-up rotor resistance in Ohm. This input is only

relevant in case of rotor resistance start-up. C start Qc M** Reactive power in kvar, which will be compensated at

voltage Un. This input is only relevant in case of capacitor start-up. The capacity C, which will be inserted parallel to the motor, is: C = Qc / Un2

Cascading n cascade M** The values C, Rr or Zs (Rs, Xs) will be cascade during

the start-up, if the start-up type will be "C", "R rotor" or "Z stator". The values will be changed as follows: Ci = C - (i - 1) * C / n Rri = Rr - (i - 1) * Rr / n



Zsi = Zs - (i - 1) * Zs / n The running variable i (cascade i) begins at 1 and is incremented by 1 during the start-up, according to the n time resp. slip areas (see "t switch", "s switch").

Mechanical Load

H M** Inertia constant. J M** Moment of inertia in kgm². Load torque Given as M** The load torque characteristic may be entered by a Table

or a Parabola. Table M** The Table can be chosen from a Library. Parabola M0, M1, M2 M** Parameters of quadratic starting characteristic (Parabola)

Mload(s)=M0+M1*(1-s)+M2*(1-s)² in Nm (s: slip) or related to the rated torque of the motor (see below).

Nm M** Gives the units of the load torque: Nm (checkbox checked) or related to the rated torque of the motor.

Load Table Entries s, M load M** The load torque may be entered as a table with user

defined points. Remark: The load torque is described by the equation: Ml = M0 + (1 - s) · M1 + (1 - s) 2 · M2 (parabola) or Ml = Ml(s) (characteristic (table entries)) The input of Ml(s) is more significant as the input of M0, M1 and M2. Voltage drop calculation: All values marked with (M*) are necessary. Motor starting calculation: All values marked with (M*) or (M**) are necessary.



Cosphi characteristic curve (AM)

Cosphi min

Cosphi max

P maxP min P lim

Cosphi oper

P

Fig. 4.36 Cosphi characteristic curve

Description of the Model (SC) (AM)

R

X

Fig. 4.37 Model of asynchronous machine for short-circuit calculation The model parameters of the positive sequence are calculated as follows: Positive sequence:

Z = η·cos(phi)·Ur² / [Prmech·(Ia/Ir)·n] n: number of ASM X = Z / √((Rm/Xm)²+1) R = X · (Rm/Xm)

The ratio Rm/Xm will be set according to IEC, if Rm is set to 0:

• Rm/Xm = 0.1 for high voltage motors with active power Pr per Pole pair >= 1MW

• Rm/Xm = 0.15 for high voltage motors with active power Pr per Pole pair < 1MW



• Rm/Xm = 0.42 for low voltage motors The impedance Z = R + j·X of zero sequence is set to infinity.

Remark: For a thyristor fed motor (corresponding checkbox must be checked) the following values are assumed:

• Ia/Ir = 3 • Rm/Xm = 0.1



PS-Block

This chapter describes the parameters of the Data Input Dialog of a Power Station Block and the corresponding model.

PS-Block – Parameters

Name Name of element. Type Applicable only with a "Power Station Block" library.


Unit transformer Ur1, Ur2 SMHP Rated voltage of the node 1 and 2 in kV. Sr SMHP Rated power of the transformers in MVA. Vector group SP Wiring of the windings in node 1 and 2. Default-value:

YY.00 . uRr(1) SMHP Positive sequence copper losses in % with respect to

Sr (of transformer) and Ur1. ukr(1) SMHP Positive sequence short circuit voltage in % with

respect to Sr and Ur1. uRr(0) SP Zero sequence copper losses in the windings 1 and 2

in % with respect to Sr and Ur1. ukr(0) SP Zero sequence short circuit voltage in % with respect

to Sr and Ur1. Earthing SP Indicates de type of earthing of the unit transformer. Re1, Xe1 SP Real- and imaginary part of earthing impedance in

Ohm, on primary side (winding 1). Unit generator Sr SMHP Rated power of generator in MVA. xd" sat SMHP Saturated subtransient reactance in % with respect to

Sr (of generator) and Ur2. x(2) SP Negative sequence reactance x(2)=0.5 (xd"+xq") in %

with respect to Sr (of generator) and Ur2. Cos(phi) SMHP Power factor. xd sat. SP Synchronous reactance in % with respect to Sr (of

generator) and Ur (saturated value). Ufmax/Ufr SP Ratio of highest possible excitation voltage to rated



excitation at rated load and power factor. Turbo SP Checkbox to indicate the type of the synchronous

machine. Operational data P oper LMDR Input of active power in MW. For generating power the

value for P must be given as positive value. For loads the value must be given as negative value.

Q oper LMDR Input of reactive power in Mvar. Positive value means generation of capacitive reactive power (overexcited generator); negative value means consumption of capacitive reactive power (under excited generator).

PS Block – Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

PS Block - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

PS Block - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

PS Block - More… Frequency dependence… By pressing this button of the More tab, the Frequency dependence input parameters can be entered. They are only used for harmonic analysis. The description can be found in Frequency dependence of chapter Data Input Dialogs of Network Elements-Element - More on page 4-4. Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description



can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6.

Description of the Model (PS Block)

t : 1

3 · Ze1 Z RT G

X G

Fig. 4.38 Model of power station block in the positive and negative system The model parameters of the positive and negative sequence are calculated as follows: Positive sequence Negative sequence ZT = ukr(1)·Ur1²/(Sr·100) ZT = ukr(1)·Ur1²/(Sr·100) RT = uRr(1)·Ur1²/(Sr·100) RT = uRr(1)·Ur1²/(Sr·100) XT = √(ZT²-RT²) XT = √(ZT²-RT²) ZT = RT + j·XT ZT = RT + j·XT RG = Rf RG = Rf XG = xd"·Ur²/(100·SrG) XG = x(2)·Ur²/(100· SrG) ZG = RG + j·XG ZG = RG + j·XG

The model of the power station block in the zero sequence depends on the vector group of the transformer. Because the star point of the transformer is not grounded on generator side, the only transformers with vector groups ZY and YD can lead a zero sequence current.



3 · Ze

Z T

Fig. 4.39 Model of power station block (vector groups YD or ZY) in the zero sequence

Zero sequence ZT = ukr(0)·Ur1²/(Sr·100) RT = uRr(0)·Ur1²/(Sr·100) XT = √(ZT²-RT²) ZT = RT + j·XT Ze1 = Re1 + j·Xe1

The parameter RG (resistance) is set in function of Ur and Sr according to IEC: RG = 0.05·xd" (for Ur > 1 kV and Sr >= 100 MVA) RG = 0.07·xd" (for Ur > 1 kV and Sr < 100 MVA) RG = 0.15·xd" (for Ur <= 1 kV)

Remarks: The power station block is only for short circuits according to IEC909. For all other calculation, also short circuit calculation according to IEC60909, it is more convenient to represent a generator and a transformer separately. According to IEC the impedances ZT and ZG must be multiplied by the factor K: IEC909 K = cmax/(1+(xd"-XT)·sin(phi)) considering the voltage ratio. IEC60909 The correction factors are given in die sections for data input for generators and transformers.



Load

This chapter describes the parameters of the Data Input Dialog of a Load and the corresponding model.

Load – Parameters

Name Name of element. Type Applicable only with a load library. Pressing the button


Lf-Type () Type of node for load flow calculation. Possible values: • "PQ": P,Q-node. Input of the values "P" and "Q"

compulsory (see below). • "PC": P,C-node. Input of the values "P" and

"cos(phi)" compulsory (see below). • "IC": I,C-node. Input of the values "I" and

"cos(phi)" compulsory (see below). • "PI": P,I-node. Input of the values "P" and "I"

compulsory (see below). • "SC": S,C-node. Input of the values "S" and

"cos(phi)" compulsory (see below). • "EC": E,C-node. Input of the values "E",

"Velander factor 1", "Velander factor 2" and "cos(phi)" compulsory (see below).

Units () Indicates if the values P, Q and I are given for low or high voltage. Possible values:

• HV: High voltage • LV: Low voltage

The default value can be given in the Edit Options mask (see "Edit Options" in chapter "Menu Insert"). When introducing a new load the default unit will be taken.

S () Consumed power in MVA or kVA. Dependent on the phase connectivity (see Info tab) the value must be entered as phase value.

P () Consumed active power in MW or kW. Dependent on the phase connectivity (see Info tab) the value must be entered as phase value.

Q () Consumed reactive power in Mvar or kvar. Dependent



on the phase connectivity (see Info tab) the value must be entered as phase value.

I () Amount of load current in kA or A. Dependent on the phase connectivity (see Info tab) the value must be entered as phase value.

cos (phi) () Power factor of the load. Dependent on the phase connectivity (see Info tab) the value must be entered as phase value.

E () Total yearly energy consumption in MWh or kWh. Conversion into P with Velander-Coefficients:

EkvelEkvelP ⋅+⋅= 21 Velander factor 1

() Velander-Coefficient 1

Velander factor 2


P(0) SP Consumed active power in the zero system in MW or kW.

Q(0) SP Consumed reactive power in the zero system in Mvar or kvar.

Domestic units

() Number of domestic units (see below).

Total scaling factor for P

() Indicates the total scaling factor for the active power of the load. It is calculated by the product of the network, of the zone, of the assigned and of the calculated scaling factor for P: ftp=fnp*fzp*fap*fc

Total scaling factor for Q

() Indicates the total scaling factor for the reactive power of the load. It is calculated by the product of the network, of the zone, of the assigned and of the calculated scaling factor for Q: ftq=fnq*fzq*faq*fc

Scaled values

() The scaled values for Poper, Qoper, Soper, Ioper and Cos(phi)oper are calculated with P and Q and the respective scaling factors: Poper= P* ftp ; Qoper= Q* ftq

Equivalent circuit for harmonic analysis

H Defines, if R and L are connected in series or in parallel.

Load Balancing Load variable

L Indicates, if the load is variable during load balancing calculation. If yes and if the option "Set calculated



values" is active in the Load flow Parameters, then the calculated scaling factor will be written in the respective field of the load (see below).

Calculated scaling factor (P,Q)

() Shows the calculated scaling factor after a load flow calculation with load balance if the load is variable and if the option "Load balance - Set calculated values" in the Load flow Parameters is active. The factor can be modified manually after a load balancing calculation. It will be multiplied by the effective scaling factor.

The values P, Q, I and cos(phi) will be calculated dependent on input.

Load – Voltage Dependency

Name Name of element. Voltage dependency model

LDR The user may choose between two equivalent static load models, the exponential model and the composite model.

Exponential model XP LDR Voltage exponential factor for active power. XQ LDR Voltage exponential factor for reactive power. Composite model (ZIP model) Csp LDR constant power fraction of active load Csq LDR constant power fraction of reactive load Cip LDR constant current fraction of active load Ciq LDR constant current fraction of reactive load Czp LDR constant impedance fraction of active load Czq LDR constant impedance fraction of reactive load. Ua1 D Upper voltage limit for a reduction factor R(u)=1. Ua2 D Upper voltage limit for a reduction factor R(u)=0. Ub1 D Lower voltage limit for a reduction factor R(u)=1. Ub2 D Lower voltage limit for a reduction factor R(u)=0. Frequency dependency Fp D frequency-dependence factor of active load Fq D frequency-dependence factor of reactive load



Load – Scaling Factors

Operating Mode

() Indicates if the load is working as a load or as a generator, depending on the sign of the active power P. For the load mode, P has to be positive, for generator mode negative.


() Displays the predefined scaling factors of P and Q for the network. Depending on the Operating Mode, these are the scaling factors for generation or load. Predefined scaling factors may be changed in Edit - Data - Operational Data (see chapter Menu Options).


() Displays the predefined scaling factors of P and Q for the zone. Depending on the Operating Mode, these are the scaling factors for generation or load. Predefined scaling factors may be changed in Edit - Data - Operational Data (see chapter Menu Options).

Assigned scaling factors

() Displays the scaling factors of P and Q, assigned to this load. It's a total of the assigned user defined scaling factors.

Effective scaling factors

() Displays the effective scaling factors of P and Q for this load. It's the product of the network- the zone- and the assigned scaling factor: fe=fn*fz*fa This scaling factor will be multiplied by the calculated scaling factor to get the total scaling factor. (see Load-Parameters)

Assign user defined scaling factors Table () The user has the possibility to assign one or more user

defined scaling factors. Every user defined scaling factor may consist of a constant factor (P-factor, Q-factor) and a time dependent factor (characteristics). If there are various user defined scaling factors in the table, a total factor has to be calculated with help of the portion. The portion may be defined directly in the table and it has to be considered that the total of all portions cant exceed 100%. That's why it's necessary to lower first a portion before increasing an other one. The total of all assigned user defined scaling factors is displayed in the fields "Assigned scaling factor and its calculated as follows: faP= p1 * Pfactor1 + p2 * Pfactor2 + faQ= p1 * Qfactor1 + p2 * Qfactor2 + p = Portion



For simulations with the module Load Flow with Load Profiles the time dependent scaling factor gets into the equation: faP= p1 * Pfactor1 * Pfactor_t1(t) + p2 * Pfactor2 * Pfactor_t2(t) + faQ= p1 * Qfactor1 * Qfactor_t1(t) + p2 * Qfactor2 * Qfactor_t2(t) +

Insert () Inserts in the table a time dependent scaling factor, which can be chosen from a list of all defined factors.

Remove () Removes the marked scaling factor from the table. Define scaling factors

() Enters in the Scaling Factors Editor, where the user may define Scaling Factors and the time-dependent characteristic curves (see chapter User Defined Scaling Factors on page 4-151).

Show characteristic

() Shows the time dependent characteristic curves of the Scaling Factor Type marked in the table.

Load – Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Load - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Load - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

Load - More… Frequency dependence… By pressing this button of the More tab, the Frequency dependence input parameters can be entered. They are only used for harmonic analysis. The




Mixed Load Power (Load) The consumed power of a load consists of

• a general load P and Q (input see above) and • a load due to the number of domestic units nDU.

The active power PDU and the Cos(phi), which are assigned to one domestic unit, are entered in the load flow parameter mask. In the Scaled values of the Params tab of the load data input dialog, the power Poper and Qoper represent the sum of the general load and the domestic loads, multiplied by the effective scaling factor: Poper = fep(P + nDU · PDU) Qoper = feq(Q + nDU · PDU · Sin(phi) / Cos(phi)) When calculating the load flow accordingly to the voltage drop method an other power will be set for mixed load power (see chapter "Load Flow").

Description of the Model (Load) See chapter "Load Flow".

Description of the Model (Load) (Short circuit according to superposition method) For short circuit calculation, the loads are considered only, when the superposition method is used, but not for the IEC and ANSI norm. The loads are considered in the positive, negative and zero system when calculating short circuit according to superposition method. Otherwise they are not considered. The model is similar to that one of the shunt element, which means the loads are represented by impedances:



R

X

Fig. 4.40 Model of a Load for SC-calculation with superposition methode The model parameters of the positive and zero sequence are calculated as follows:

Positive system Zero system R = P(1)·U²/(P(1)²+Q(1)²) R = P(0)·U²/(P(0)²+Q(0)²) X = Q(1)·U²/(P(1)²+Q(1)²) X = Q(0)·U²/(P(0)²+Q(0)²) U Calculated with a load flow. If no load flow has

been calculated, the program set U = Un (Un: nominal system voltage).

Static load models (Voltage dependence) The user may choose between two equivalent static load models, the exponential model and the composite model (see Load Voltage Dependency). For both models a frequency dependency may be defined and for the composite model, a reduction factor can be applied additionally.

Exponential model Traditionally, the voltage dependency of load characteristics has been represented by the exponential model:

⋅∆+⋅

⋅= p

xP

Fff

uupp

000 1



⋅∆+⋅

⋅= q

xQ

Fff

uuqq

000 1

The parameters of this model are the exponents xP and xQ. With these exponents equal to 0, 1 or 2, the model represents constant power, constant current or constant impedance characteristics, respectively. For composite loads, their values depend on the aggregate characteristics of load components. p : ongoing active load q : ongoing reactive load p0 : initial active load q0 : initial reactive load u : magnitude of ongoing node voltage uo : magnitude of initial voltage (nominal system voltage) f0 : rated frequency ∆f : frequency difference from rated frequency

Composite model (ZIP model) An alternative model which has been widely used to represent the voltage dependency of loads is the composite model (ZIP model):

⋅∆+⋅

⋅+⋅+⋅= pzpipsp F

ff

uuc

uuccpp

020

2

00 1

⋅∆+⋅

⋅+⋅+⋅= qzqiqsq F

ff

uuc

uuccqq

020

2

00 1

spipzp ccc −−=1

sqiqzq ccc −−=1 The model is composed of constant impedance (Z), constant current (I) and constant power (P) components. The parameters of the model are the coefficients csp, cip, czp and csq, ciq, czq, which define the proportion of each component.



Frequency dependency The frequency dependency of the load characteristics is represented by multiplying the exponential model or the composite model by a factor

⋅∆+ F

ff0

1 , where ∆f is the frequency deviation (f-f0).

Typically, Fp ranges from 0 to 3.0, and Fq from 2.0 to 0.

Reduction factor It is physically impossible for a load to retain its constant current or power character at very high or very low voltages. Theoretically, for example, an infinitely high current would have to be provided for a constant power at a voltage of 0. In the dynamic simulation, particularly during short-circuits, very low voltages are encountered, at which a constant current or a constant level of power is not plausible. In cases of this kind, there may also be convergence problems at short-circuit inception. As a remedy for these physical and mathematical problems, the supply current is downsized with a reduction factor if the voltage is too high or too low. For voltages greater than umax or smaller than umin, the reduction factor is downsized from 1 to 0 using a continuous function. Mathematically, the reduction factor is represented by:

−−

−=>

=≤≤

−−

−=

0;1

1uuu

0;1u<u

2

21

1)(1

)(11

2

21

1)(b1

aa

aua

uab

bb

bu

uuuu

MAXRuu

Ruuuu

MAXR

For the values ub1 = 0.9 pu ; ub2 = 0.75 pu ua1 = 1.1 pu ; ua2 = 1.25 pu the behavior of the reduction factor is illustrated below:



1

0

R(u)

Voltage dependence of the reduction factor

0.75 0.9 1.0 1.1 1.25 u [pu]

ub1 ua1

ub2 ua2

Fig. 4.41 Voltage dependence of the reduction factor The reduction factor is used only in the composite model. R(u) is reducing the constant current and the constant power factors by multiplication:

⋅∆+⋅

⋅+⋅⋅+⋅⋅= pzpipuspu F

ff

uuc

uucRcRpp

020

2

0)()(0 1

⋅∆+⋅

⋅+⋅⋅+⋅⋅= qzqiqusqu F

ff

uuc

uucRcRqq

020

2

0)()(0 1

spuipuzp cRcRc ⋅−⋅−= )()(1

squiquzq cRcRc ⋅−⋅−= )()(1



DC Load

This chapter describes the parameters of the Data Input Dialog of a DC Load and the corresponding model.

DC Load – Parameters

Name Name of element. Type Applicable only with a load library. Pressing the button


Regulation () Type of node for load flow calculation. Possible values: • "P": P-node. Input of the values "Pset"

compulsory (see below). • "I": I-node. Input of the values "I set" compulsory

(see below). • "R": R-node. Input of the values "R set"

compulsory (see below). P set () Consumed DC power at node in MW. I set () Amount of DC load current in kA. R set () Load DC resistance in Ohm.

DC Load – Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

DC Load - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

DC Load - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



DC Load - More… Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6.



Line Load

This chapter describes the parameters of the Data Input Dialog of a Line Load and the corresponding model. There are two possibilities to assign a line load to a line. If the user wants the line load to be represented graphically, the line load symbol has to be chosen in the Symbol Window and pasted on the respective line. The Data Input Dialog appears. If a graphical representation of the line load isnt necessary, its possible to enter the line loads in the Data Input Dialog of the respective line by pressing the Line loads button in the More… tab. In this window also the line loads, which have been entered graphically, appear. The Input-Data is shown in tabular form. By double clicking on the number of the respective line load, the Data Input Dialog opens. Also more than one line load may be entered per line.

Line Load – Parameters

Name Name of element. Type Applicable only with a line load library. Pressing the


Lf-Type () Type of node for load flow calculation. Possible values: • "PQ": P,Q-node. Input of the values "P" and "Q"

compulsory (see below). • "PC": P,C-node. Input of the values "P" and

"cos(phi)" compulsory (see below). • "IC": I,C-node. Input of the values "I" and

"cos(phi)" compulsory (see below). • "PI": P,I-node. Input of the values "P" and "I"

compulsory (see below). • "SC": S,C-node. Input of the values "S" and

"cos(phi)" compulsory (see below). • "EC": E,C-node. Input of the values "E",

"Velander factor 1", "Velander factor 2" and "cos(phi)" compulsory (see below).

Units () Indicates if the values P, Q and I are given for low or high voltage. Possible values:



• HV: High voltage • LV: Low voltage

The default value can be given in the Edit Options mask (see "Edit Options" in chapter "Menu Insert"). When introducing a new load the default unit will be taken.

S () Consumed power in MVA or kVA. Dependent on the phase connectivity (see Info tab) the value must be entered as phase value.

P () Consumed active power in MW or kW. Dependent on the phase connectivity (see Info tab) the value must be entered as phase value.

Q () Consumed reactive power in Mvar or kvar. Dependent on the phase connectivity (see Info tab) the value must be entered as phase value.

I () Amount of load current in kA or A. Dependent on the phase connectivity (see Info tab) the value must be entered as phase value.

cos (phi) () Power factor of the load. Dependent on the phase connectivity (see Info tab) the value must be entered as phase value.

E () Total yearly energy consumption in MWh or kWh. Conversion into P with Velander-Coefficients:

EkvelEkvelE ⋅+⋅= 21 Velander factor 1


Velander factor 2


Distance () Distance of the load in m or in % from the starting node of the line.

Domestic units

() Number of domestic units (see below).

Total scaling factor for P

() Indicates the total scaling factor for the active power of the line load. It is calculated by the product of the network and the zone scaling factor, the scaling factor of the line load and the calculated scaling factor. P: fep=fnp*fzp*fs*fc

Total scaling factor for Q

() Indicates the total scaling factor for the reactive power of the line load. It is calculated by the product of the network and the zone scaling factor, the scaling factor



of the line load and the calculated scaling factor. Q: feq=fnq*fzq*fs*fc

Scaling factor

() Scaling factor of the line load for the active and reactive power. This factor will be multiplied by the network and the zone scaling factor as well as with the calculated scaling factor.

Scaled values

() The scaled values for Poper, Qoper, Soper, Ioper and Cos(phi)oper are calculated with P and Q and the respective scaling factors: Poper= P* fep ; Qoper= Q* feq

Load Balancing Calculated scaling factor (P,Q)

() Shows the calculated scaling factor after a load flow calculation with load balance if the option "Load balance - Set calculated values" in the Load flow Parameters is active. The factor can be modified manually after a load balancing calculation. It will be multiplied by the network and the zone scaling factor and by the scaling factor of the line load.

Remark: The predefined scaling factors for the network and zones may be modified in Data - Operational Data of the menu Edit (see chapter Menu Options).

Line Load - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Line Load - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Line Load - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Mixed Load Power (Line Load) The consumed power of a load consists of

• a general load P and Q (input see above) and • a load due to the number of domestic units nDU.

The active power PDU and the Cos(phi), which are assigned to one domestic unit, are entered in the load flow parameter mask. The power, which will be taken by the load flow is correspondingly: Pcal = P + nDU · PDU Qcal = Q + nDU · PDU · Sin(phi) / Cos(phi) The powers Pcal and Qcal are multiplied by the simultaneity factor. When calculating the load flow accordingly to the voltage drop method, an other power will be set for mixed load power (see chapter "Load Flow").

Assignment of the Loads to the Line Load Center The line loads are assigned to a new node on the line. During load flow calculation this node will be generated automatically by the program in the load center of the line. The load center is calculated as follows:

( )∑∑ ⋅=⋅ lltotl lPlP

( ) ∑∑ ⋅= llltot PlPl

with Pl Active power of the line load ll Distance of the line load from the lines starting node ltot Distance of the line load center from the lines starting node

The new node, which is generated in a distance of ltot from the lines starting node, gets an arbitrary name. The sum of all loads of the line is assigned to this node. If the load center is closer than 7m from the lines starting or ending node, no new node will be generated. Then the line loads are assigned to either the starting node or ending node. The position of the line load symbol has nothing to do with the load center. To the line load symbol no results are assigned.



Description of the Model (Line Load) See chapter "Load Flow".

Phasing of the line loads The line loads have the same phasing connectivity as the line itself. A single phase line for example carries only single phase loads.



User Defined Scaling Factors

The user can define constant scaling factors and time-dependent scaling factors for day-times, week-days, moths and years. The factors may be defined only in the project or they can be saved to a library. There exist the following possibilities to enter in the user defined scaling factors editor:

To define Scaling Factors and time-dependent characteristics to a library, while the project wont be modified: • Menu Libraries Scaling Factors To define Scaling Factors and time-dependent characteristics directly in the project, to export them to a library or to get them from a library: • Menu Edit Data Define Scaling Factors • Data Input Dialog of an element tab Scaling Factors Define Scaling

Factors To calculate the Effective Scaling Factors for a certain element, the User Defined Scaling Factors are multiplied with the Predefined Scaling Factors for the network and zones. Predefined Scaling Factors may be modified in Edit - Data Operational Data. For more information about Predefined Scaling Factors see chapter Menu Options.

Scaling Factors A list of all existing Scaling Factor types appears after having selected the tab Scaling Factors in the Scaling Factor Editor. For every type the user can define constant scaling factors and time-dependent scaling factors. Scaling Factor types may be added or removed.

Types Shows all existing Scaling Factors types. With New, a type can be added; with Delete a type may be removed.

Description Description of the Scaling Factors type. Constant factor for manual scaling

Constant scaling factor for P and Q.

Time-dependent factor

The time-dependent factor is composed of a "Day by Hours" characteristic, a "Week by Days" characteristic, a "Year by Months" characteristic and a "Long Term by Years" characteristic (see below). By pressing the button Select the characteristic curves may be selected.



The time-dependent scaling factor is used only for the module "Load Flow with Load Profiles" and it is calculated as follows: Pfactor_t(t) = fd(t)*fw(t)*fy(t)*fl(t) Qfactor_t(t) = fd(t)*fw(t)*fy(t)*fl(t)

Day by Hours Characteristics A list of all existing "Day by Hours" characteristics appears after having selected the respective tab in the Scaling Factor Editor. By clicking on a characteristic type, the corresponding curve will be displayed and its values may be modified. Characteristic types may be added or removed.

Types Shows all existing day characteristics types. With New, a type can be added; with Delete a type may be removed.

Description Description of the day characteristic type. Time-value-table Definition table. The program interpolates linearly between

two points. In maximum 1440 time values may be entered; for every seconde a value.

Time Time (hour and minutes), editable directly in the table. Factors A P-factor and a Q-factor between 0 and 1 may be entered

or edited directly in the table. Insert 1 item Inserts one time value after the marked line. If no line is

selected, the additional value will be added at the end of the table.

Insert items Inserts the indicated amount of time values after the marked line. If no line is selected, the additional time values will be added at the end of the table.

Remove Removes the marked time values. Same values for P and Q scaling

If this checkbox is active, the Q factors of the table wont be considered. Instead the Q factors will be the same as the P scaling factors.

Week by Days Characteristics A list of all existing "Week by Days" characteristics appears after having selected the respective tab in the Scaling Factor Editor. By clicking on a characteristic type, the corresponding curve will be displayed and its values may be modified. Characteristic types may be added or removed.



Types Shows all existing week characteristics types. With New, a type can be added; with Delete a type may be removed.

Description Description of the week characteristic type. Day values For all days, Monday to Sunday, a P and a Q factor

between 0 and 1 may be entered. The values will be presented with bars in the graphic of the week characteristics.

Same values for P and Q scaling


Year by Months Characteristics A list of all existing "Year by Months" characteristics appears after having selected the respective tab in the Scaling Factor Editor. By clicking on a characteristic type, the corresponding curve will be displayed and its values may be modified. Characteristic types may be added or removed.

Types Shows all existing month characteristic types. With New, a type can be added; with Delete a type may be removed.

Description Description of the month characteristic type. Month values For all months, January to December, a P and a Q factor

between 0 and 1 may be entered. The values will be presented with bars in the graphic of the week characteristics.

Same values for P and Q scaling


Long Term by Years Characteristics A list of all existing "Long Term by Year" characteristics appears after having selected the respective tab in the Scaling Factor Editor. By clicking on a characteristic type, the corresponding curve will be displayed and its values may be modified. Characteristic types may be added or removed.



Types Shows all existing year characteristic types. With New, a type can be added; with Delete a type may be removed.

Description Description of the year characteristic type. Year values For every year a P and a Q factor between 0 and 1 may be

entered. Year Year (4 digits: e.g. 2004) for which a P and a Q factor

should be defined. P scaling P-factor for the respective year. Q-factor Q-factor for the respective year. Insert Inserts a year value. Remove Removes a year value. Same values for P and Q scaling


Library Import / Export If the user doesnt modify the Scaling Factors directly in the Library Menu, the Library wont be modified. In this case it exists the possibility to export or import Scaling Factors and Characteristics to and from the library.

Actual project The list contains all scaling factors and characteristic types defined in the project. They may be selected, unselected or deleted.

Selected library The list contains all scaling factors and characteristic types defined in the active library. They may be selected, unselected or deleted.

Open Library An existing library may be opened. New Library A new library may be created. >> <<

By pressing these buttons, the selected types may be copied from the project to the library or from the library to the project.



Filter

This chapter describes the parameters of the Data Input Dialog of a filter and the corresponding model.

Filter – Parameters

Name Name of element. Type Applicable only with a filter library. Pressing the


Ur () Rated voltage in kV. C-Filter () Idicates if the filter is a C filter. HP-Filter () Idicates if the filter is a HP filter.

To enter the data there are two possibilities:

Type 1:

Qr () Reactive power of filter in kvar of positive sequence. The power is given as a positive value, although the power is capacitive.

f0 () Resonance frequency in Hz. G () Q factor of filter in pu. Damp.factor () Damping factor (only relevant for C-filter and HP-

filter)

Type 2:

Rv () Resistance of filter in Ohm. The losses are represented.

L () Inductance of filter in mH. C () Main capacitance of filter in µF. Cs () Auxiliary capacitance of filter in µF (only relevant for

C-filter). Rd () Damping resistance of the filter in Ohm (only

relevant for C-filter and HP-filter).



Filter – Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Filter - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Filer - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

Filter - More… Frequency dependence… By pressing this button of the More tab, the Frequency dependence input parameters can be entered. They are only used for harmonic analysis. The description can be found in Frequency dependence of chapter Data Input Dialogs of Network Elements-Element - More on page 4-4. Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6.

Description of the Model (Filter)



C Rv L

C Rv L

Rd

a) normal filter

b) HP-filter

Cs Rv L

Rd

c) C-filter

C

Fig. 4.42 Model of a filter The positive sequence will be used in any case, excepted in the short circuit calculation according to IEC. The zero sequence will be only considered in the short circuit calculation. If the parameters Qr, f0, G, DF are entered, the program will calculate the parameters Rv, L, C, Rd and vice versa. The formulas are: Calculation from Qr, f0, G, DF to Rv, L, C, Cs, Rd:

fnfn 0=

QrUrfnn

nCh ⋅⋅⋅⋅

⋅−= 22

2

211

ππππ



ChfnL

⋅⋅⋅= 2)2(

1ππππ

GLfRv ⋅⋅⋅= 02 ππππ

a) Normal filter:

ChC =

0.0=Rd

b) HP-filter:

ChC =

DFCLRd ⋅= DF: Damping factor

c) C-filter:

2)2(0.1

fnLCs

⋅⋅⋅=

ππππ

CsChC 11

0.1−

=

DFCLRd ⋅= DF: Damping factor

Calculation from Rv, L, C, Rd to Qr, f0, G, DF:

a) Normal filter:

CCh =

0.0=Rd

b) HP-filter:

CCh =

RdLCDF ⋅= DF: Damping factor

c) C-filter:



CsCCh 11

0.1+

=

RdLCDF ⋅=

For all filters equal:

n ffn

= 0

ChLf

⋅⋅⋅=

ππππ210

22

2

21

UrfnChn

nQr ⋅⋅⋅⋅⋅−

= ππππ

RvLfG ⋅⋅⋅= 02 ππππ

with fn as nominal system frequency in Hz.



Serie-R-L-C (without Earth Connection)

This chapter describes the parameters of the Data Input Dialog of a Serie-R-L-C (without Earth Connection) and the corresponding model.

Serie-R-L-C – Parameters

Name Name of element. Type Applicable only with an RLC-Circuit library. Pressing


Ur () Rated voltage in kV. Rv () Resistance in Ohm. L () Inductance in mH. C () Capacitance in µF.

Serie-R-L-C – Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Serie-R-L-C - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Serie-R-L-C - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

Serie-R-L-C - More… Frequency dependence… By pressing this button of the More tab, the Frequency dependence input parameters can be entered. They are only used for harmonic analysis. The




Description of the Model (Serie-RLC) The following possibilities exist to enter the Serie-RLC circuit.

R

L

C



R L

CR

CL

CR L

Fig. 4.43 Possibilities to introduce the Serie-RLC circuit without earth connection With this element the user will be able to model every type of filter or an other element. The positive and the zero sequence, which are equal, are considered.



Parallel-RLC

This chapter describes the parameters of the Data Input Dialog of a Parallel-RLC circuit and the corresponding model.

Parallel-RLC – Parameters

Name Name of element. Type Applicable only with a Parallel-RLC library. Pressing


Ur () Rated voltage in kV. To input the data there are two possibilities:

Type 1:

Sr () Throughput power of low frequency filter in kVA. f0 () Resonance res. stop frequency of filter in Hz. G () Q factor of filter in pu. P () Nominal reactance of filter in %.

Type 2:

Rv () Resistance of low frequency filter in Ohm. L () Inductance of low frequency filter in mH. C () Capacitance of low frequency filter in µF.

Parallel-RLC – Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Parallel-RLC - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.



Parallel-RLC - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

Parallel-RLC - More… Frequency dependence… By pressing this button of the More tab, the Frequency dependence input parameters can be entered. They are only used for harmonic analysis. The description can be found in Frequency dependence of chapter Data Input Dialogs of Network Elements-Element - More on page 4-4. Investment Data… By pressing this button of the More tab, the Investment Data input parameters can be entered. They are only used for investment analysis. The description can be found in Investment Analysis of chapter Data Input Dialogs of Network Elements-Element - More on page 4-6.

Description of the Model (Parallel-RLC)

R

L

C

Fig. 4.44 Model of a Parallel-RLC resonance circuit The positive and zero sequence, which are equal, are considered. From Sr, f0, G and p the program will calculate Rv, L and C. The way round is not possible. Calculation from Sr, f0, G, p to Rv, L, C:

SrUrp

fnL

2

10021 ⋅⋅⋅⋅

=π



L)f(C

⋅⋅⋅= 202

1π

CLGRv /⋅=

with fn as nominal system frequency.



Serie-E-RLC (with Earth Connection)

This chapter describes the parameters of the Data Input Dialog of a Serie-E-RLC circuit and the corresponding model.

Serie-E-RLC – Parameters

Name Name of element. Type Applicable only with a Serie-E-RLC library. Pressing


Ur () Rated voltage in kV. Rv () Resistance in Ohm. L () Inductance in mH. C () Capacitance in µF.

Serie-E-RLC– Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Serie-E-RLC - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Serie-E-RLC - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

Serie-E-RLC - More… Frequency dependence… By pressing this button of the More tab, the Frequency dependence input parameters can be entered. They are only used for harmonic analysis. The




Description of the Model (Serie-E-RLC) The possibilities to enter the Serie-E-RLC circuit:

R

L

C



R L

CR

CL

CR L

Fig. 4.45 Possibilities to input the Serie-E-RLC circuit in serie with earth connection With this element the user will be able to model every type of filter or an other element. The positive sequence will be used in any case, excepted in the short circuit calculation according to IEC. The zero sequence will be only considered in the short circuit calculation.



Disconnect-Switch

Its possible to enter Disconnect Switches between two nodes. This chapter describes the parameters of the Data Input Dialog of a Disconnect-Switch.

Disconnect-Switch – Parameters

Name Name of element. Type Applicable only with a Disconnect-Switch library. Pressing


remote controlled


Urmax SP Maximum voltage for which the switch is designed and upper limit of operation in kV.

Ir LM Rated current of switch in kA. Ik" SP Max. allowable initial short circuit current or Close & latch

rating of the switch kA. Ibmax SP Max. allowable breaking current or interrupting rating of

the switch in kA. For disconnect switch no input necessary.

Ipmax SP Max. allowable peak short circuit current in kA. r(1) D Positive sequence resistance in mOhm. r(0) D Zero sequence resistance in mOhm. x(1) D Positive sequence reactance in mOhm. x(0) D Zero sequence reactance in mOhm.




Disconnect-Switch – Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Disconnect-Switch - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Disconnect-Switch - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Load-Switch

Its possible to enter load switches between two nods. This chapter describes the parameters of the Data Input Dialog of a Load-Switch.

Load-Switch – Parameters

Name Name of element. Type Applicable only with a Load-Switch library. Pressing the


remote controlled



Ir LM Rated current of switch in kA. Ik" SP Max. allowable initial short circuit current or Close & latch

rating of the switch kA. Ibmax SP Max. allowable breaking current or interrupting rating of

the switch in kA. For disconnect switch no input necessary.

Ipmax SP Max. allowable peak short circuit current in kA. R(1) D Positive sequence resistance in mOhm. R(0) D Zero sequence resistance in mOhm. x(1) D Positive sequence reactance in mOhm. x(0) D Zero sequence reactance in mOhm.




Load-Switch – Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Load-Switch - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Load-Switch - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Circuitbreaker

Its possible to enter Circuitbreakers between two nods. This chapter describes the parameters of the Data Input Dialog of a Circuitbreaker.

Circuitbreaker – Parameters

Name O Name of element. Type O Applicable only with a Circuitbreaker library. Pressing the


remote controlled



Ir LM Rated current of switch in kA. Cycles SP Interrupting time of the ANSI breakers in cycles. Possible

values: 2, 3, 5, 8 cycles k-factor SP Ratio of rated maximum voltage Urmax to the lower limit

of the range of operation voltage in which the required symmetrical and asymmetrical interrupting capabilities vary in inverse proportion to the operating voltage (only for ANSI breakers).

Cosphi test SP Cos(phi) at which the breaker was tested (only for ANSI breakers).

Ik" SP Max. allowable initial short circuit current or Close & latch rating of the switch kA.

Ibmax SP Max. allowable breaking current or interrupting rating of the switch in kA. For disconnect switch no input necessary.

Ipmax SP Max. allowable peak short circuit current in kA. Standard SP Indicates the dimensioning of the breaker: breaker

according to IEC or ANSI/IEEE. HV/LV SP Indicates, if the breaker is a low or a high voltage

breaker. r(1) D Positive sequence resistance in mOhm. r(0) D Zero sequence resistance in mOhm. x(1) D Positive sequence reactance in mOhm. x(0) D Zero sequence reactance in mOhm.



Remark: The resistance and reactance for the switch model are only necessary to be introduced, when the switches are not reduced during calculation (see "Reduce" option in calculation parameters of the different calculation modules). For load flow calculations with the method "Extended Newton Rapson" these impedances are never relevant, because this LF-method is modeling the switches without impedances. For Dynamic Analysis the impedance data always have to be entered. The data of this element are also considered in the module selectivity analysis.

Circuitbreaker – Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Circuitbreaker - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Circuitbreaker - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Fuse

This chapter describes the parameters of the Data Input Dialog of a Fuse.

Fuse - Parameters

Name Name of element. Type Applicable only with a Fuse library. Pressing the button


Ir LM Rated current in A. Element Type () Type of the element where the variable is measured. Variable () Variable to be measured. Modification () Option to modify the measured variable. Element () Element to which the fuse is assigned to. Side () The side of the element (node) the fuse is assigned to. Characteristic O Button to choose a fuse type from a device library. Tripping D Button to define tripping functions for transient stability

simulations. This element will not be used for calculations. Only its allowable limits are checked. The data are considered in the module selectivity analysis and transient stability.

Fuse - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Fuse - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Fuse - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Overcurrent Relay

This chapter describes the parameters of the Data Input Dialog of an Overcurrent Relay.

Overcurrent Relay – Parameters

Name O Name of element. Type Applicable only with an Overcurrent Relay library.


Element Type () Type of the element where the variable is measured. Variable () Variable to be measured. Modification () Option to modify the measured variable. Element () Element to which the fuse is assigned to. Side () The side of the element (node) the fuse is assigned to. Characteristic O Button to choose a fuse type from a device library. Tripping D Button to define tripping functions for transient stability

simulations. This element will not be used for calculations. Only its allowable limits are checked. The data are considered in the module selectivity analysis and transient stability.

Overcurrent Relay - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Overcurrent Relay - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Overcurrent Relay - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Distance Relay

This chapter describes the parameters of the Data Input Dialog of a Distance Relay.

Distance Relay – Parameters

Name Name of element. Type Applicable only with a Distance Relay library. Pressing


This element will not be used for calculations. If the user has purchased the module "distance protection" the push button "Characteristics" is available. With this option the user can enter the starting and the tripping data as well as the grading diagram (see chapter "Distance Protection").

Distance Relay - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Distance Relay - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Distance Relay - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Frequency Relay

This chapter describes the parameters of the Data Input Dialog of a Frequency Relay.

Frequency Relay – Parameters

Name Name of element. Type Applicable only with a Frequency Relay library.


Relay type Type of relay(-setting range). Element Type () Type of the element where the variable is measured. Variable () Variable to be measured. Modification () Option to modify the measured variable. Element () Element to which the fuse is assigned to. Side () The side of the element (node) the relay is assigned to. Stages D Define stages and its tripping functions for transient

stability simulations. This element will not be used for steady state calculations. The data are considered in the module Dynamic Analysis.

Frequency Relay - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Frequency Relay - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Frequency Relay - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Voltage Relay

This chapter describes the parameters of the Data Input Dialog of a Voltage Relay.

Voltage Relay – Parameters

Name Name of element. Type Applicable only with a Voltage Relay library. Pressing


Relay type Type of relay(-setting range). Element Type () Type of the element where the variable is measured. Variable () Variable to be measured. Modification () Option to modify the measured variable. Element () Element to which the fuse is assigned to. Side () The side of the element (node) the relay is assigned to.Stages D Define stages and its tripping functions for transient


Voltage Relay - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Voltage Relay - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Voltage Relay - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Power Relay

This chapter describes the parameters of the Data Input Dialog of a Power Relay.

Power Relay – Parameters

Name Name of element. Type Applicable only with a Power Relay library. Pressing


Relay type Type of relay(-setting range). Element Type () Type of the element where the variable is measured. Variable () Variable to be measured. Modification () Option to modify the measured variable. Element () Element to which the fuse is assigned to. Side () The side of the element (node) the relay is assigned to. Stages D Define stages and its tripping functions for transient


Power Relay - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Power Relay - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Power Relay - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Current Transformer

This chapter describes the parameters of the Data Input Dialog of a Current Transformer.

Current Transformer – Parameters

Name Name of element. Type Applicable only with a Current Transformer library.


Ir1 P Rated current on primary side of CT in kA. Ir2 P Rated current on secondary side of CT in kA. Ith(1s) Thermal short circuit current in kA. Ith Thermal steady state current in kA.

This element will not be used for calculations. Only its allowable limits are checked. The ratio Ir2/Ir1 will be used by the module distance protection.

Current Transformer - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Current Transformer - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Current Transformer - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Voltage Transformer

This chapter describes the parameters of the Data Input Dialog of a Voltage Transformer.

Voltage Transformer – Parameters

Name Name of element. Type Applicable only with a Voltage Transformer library.


Ur1 P Rated voltage on primary side of VT in kA. Ur2 P Rated voltage on secondary side of VT in kA.

This element will not be used for calculations. The ratio Ur2/Ur1 will be used by the module distance protection.

Voltage Transformer - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Voltage Transformer - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Voltage Transformer - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Harmonic Current Source

This chapter describes the parameters of the Data Input Dialog of a Current Source.

Current Source – Parameters

Name H Name of element. Type H Applicable only with a Harmonic Current Source library.


Ir H Rated current in A. f / Harm. H Editing frequency in Hz or Number of harmonic. I H Editing harmonic current in A or in % related to Ir. i angle H Editing angle of harmonic current in degree. Current i in % H Checkbox: Indicates, if the currents are entered in %. Frequ. f in Hz H Checkbox: Indicates, if the frequency in Hz is entered,

or the number of the harmonic. Insert H A new table entry can be made. The input values may

be modified directly in the table. Delete H The selected table lines will be deleted.

Current Source - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Current Source - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Current Source - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Harmonic Voltage Source

This chapter describes the parameters of the Data Input Dialog of a Voltage Source.

Voltage Source – Parameters

Name H Name of element. Type H Applicable only with a Harmonic Voltage Source

library. Pressing the button "", the type may be chosen and the data can be transferred from the predefined library.

Ur H Rated voltage in kV. f / Harm. H Editing frequency in Hz or Number of harmonic. U H Editing harmonic voltage in V or in % related to Ur. u angle H Editing angle of harmonic voltage in degree. Voltage u in % H Checkbox: Indicates, if the voltages are entered in %. Frequ. f in Hz H Checkbox: Indicates, if the frequency in Hz is entered,

or the number of the harmonic. Insert H A new table entry can be made. The input values may

be modified directly in the table. Delete H The selected table lines will be deleted.

Voltage Source - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Voltage Source - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Voltage Source - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Series Equivalent LF

This chapter describes the parameters of the Data Input Dialog of a Series Equivalent for load flow calculation and the corresponding model. This element will be taken into account only for load flow calculation. There exists an other Series Equivalent element for short circuit calculation. Series Equivalent are generated by the module Network reduction in order to get the same load flow or short circuit calculation results for the reduced and original network (see module "Network reduction").

Series Equivalent (LF) – Parameters

Name Name of element. Type Applicable only with a Series Equivalent LF library.


Un1 L Nominal system voltage in kV at "from node" Un2 L Nominal system voltage in kV at "to node" R12(1), X12(1), L Positive sequence transfer impedance from "from

node" to "to node" in Ohm. R21(1), X21(1), L Positive sequence transfer impedance from "to

node" to "from node" in Ohm.

Series Equivalent (LF) - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Series Equivalent (LF) - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Series Equivalent (LF) - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Description of the Model (Series Equivalent LF) The element Y-matrix will be calculated in per unit as follows:

[ ]YY YY Y

=

11 12

21 22

with Y11 = 1.0 / Z12 Z12 = (R12 + jX12) / Zn1 Y12 = -1.0 / Z12 Zn1 = Un1

2 / Sn Y21 = -1.0 / Z21 Z21 = (R21 + jX21) / Zn2 Y22 = 1.0 / Z21 Zn2 = Un2

2 / Sn Un1 : Nominal system voltage primary side Un2 : Nominal system voltage secondary side Sn = 100MVA



Series Equivalent SC

This chapter describes the parameters of the Data Input Dialog of a Series Equivalent for short circuit calculation and the corresponding model. This element will be taken into account only for short circuit calculation. There exists an other Series Equivalent element for load flow calculation. Series Equivalent are generated by the module Network reduction in order to get the same load flow or short circuit calculation results for the reduced and original network (see module "Network reduction").

Series Equivalent (SC) – Parameters

Name Name of element. Type Applicable only with a Series Equivalent SC library.


Un1 S Nominal system voltage in kV at "from node". Un2 S Nominal system voltage in kV at "to node". R12(1), X12(1), S Positive sequence transfer impedance from "from

node" to "to node" in Ohm. R21(1), X21(1), S Positive sequence transfer impedance from "to

node" to "from node" in Ohm. R12(2), X12(2), S Negative sequence transfer impedance from "from

node" to "to node" in Ohm. R21(2), X21(2), S Negative sequence transfer impedance from "to

node" to "from node" in Ohm. R12(0), X12(0), S Zero sequence transfer impedance from "from

node" to "to node" in Ohm. R21(0), X21(0), S Zero sequence transfer impedance from "to node"

to "from node" in Ohm.

Series Equivalent (SC) - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.



Series Equivalent (SC) - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Series Equivalent (SC) - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

Description of the Model (Series Equivalent SC) The element Y-matrix will be calculated in per unit for all three sequence systems as follows:

[ ]YY YY Y

=

11 12

21 22

with Y11 = 1.0 / Z12 Z12 = (R12 + jX12) / Zn1 Y12 = -1.0 / Z12 Zn1 = Un1

2 / Sn Y21 = -1.0 / Z21 Z21 = (R21 + jX21) / Zn2 Y22 = 1.0 / Z21 Zn2 = Un2

2 / Sn Un1 : Nominal system voltage primary side Un2 : Nominal system voltage secondary side Sn = 100MVA



Shunt Equivalent LF

This chapter describes the parameters of the Data Input Dialog of a Shunt Equivalent for load flow calculation and the corresponding model. This element will be taken into account only for load flow calculation. There exists an other Shunt Equivalent element for short circuit calculation. Shunt Equivalents are generated by the module Network reduction in order to get the same load flow or short circuit calculation results for the reduced and original network (see module "Network reduction").

Shunt Equivalent (LF) – Parameters

Name Name of element. Type Applicable only with a Shunt Equivalent LF library.


Un1 L Nominal system voltage in kV at from node. R1(1), X1(1) L Positive sequence shunt impedance in Ohm. P Gen L Generated real power in MW. The sign must be

negative. Q Gen L "Generated" reactive power in Mvar. The sign must

be negative for generation (over excited generator). The sign must be positive for consumption (under excited generator).

P Loa L Consumed real power in MW. The sign must be positive.

Q Loa L "Consumed" reactive power in Mvar. The sign must be negative for generation (over excited motor). The sign must be positive for consumption (under excited motor)

Shunt Equivalent (LF) - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.



Shunt Equivalent (LF) - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Shunt Equivalent (LF) - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

Description of the Model (Shunt Equivalent LF) The element Y-matrix will be calculated in per unit as follows:

[ ]YY

=

11 0 00 0 0 0

.. .

with Y11 = 1.0 / Z1 Z1 = (R1 + jX1) / Zn1 Zn1 = Un1

2 / Sn Un1: Nominal system voltage primary side Sn = 100MVA

U)QQ(j)PP(

I genloagenloa* −⋅+−=

with I: Nodal current in the node U: Nodal voltage



Shunt Equivalent SC

This chapter describes the parameters of the Data Input Dialog of a Shunt Equivalent for short circuit calculation and the corresponding model. This element will be taken into account only for short circuit calculation. There exists an other Shunt Equivalent element for load flow calculation. Shunt Equivalents are generated by the module Network reduction in order to get the same load flow or short circuit calculation results for the reduced and original network (see module "Network reduction").

Shunt Equivalent (SC) – Parameters

Name Name of element. Type Applicable only with a Shunt Equivalent SC library.


Un1 S Nominal system voltage in kV at "from node". R1(1), X1(1) S Positive sequence shunt impedance in Ohm. R1(2), X1(2) S Negative sequence shunt impedance in Ohm. R1(0), X1(0) S Zero sequence shunt impedance in Ohm.

Shunt Equivalent (SC) - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Shunt Equivalent (SC) - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Shunt Equivalent (SC) - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Description of the Model (Shunt Equivalent SC) The element Y-matrix will be calculated in per unit for all three sequence systems as follows:

[ ]YY

=

11 0 00 0 0 0

.. .

with Y11 = 1.0 / Z1 Z1 = (R1 + jX1) / Zn1 Zn1 = Un1

2 / Sn Un1: Nominal system voltage primary side Sn = 100MVA

IP P j Q Q

Uloa gen loa gen* ( ) ( )

=− + ⋅ −

with I: Nodal current in the node U: Nodal voltage



Earth Switch

This chapter describes the parameters of the Data Input Dialog of an Earth Switch.

Earth Switch – Parameters

Name Name of element. Type Applicable only with a Earth Switch library. Pressing


remote controlled


Urmax S Maximum voltage for which the switch is designed and upper limit of operation in kV.

Ik'' S Max. allowable initial short circuit current or Close & latch rating of the switch kA.

Ir LM Rated current of switch in kA. Ibmax S Max. allowable breaking current in kA. Ipmax S Max. allowable peak short circuit current in kA.

Earth switches are not considered in the calculations.

Earth Switch - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Earth Switch - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Earth Switch - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Surge Arrester

This chapter describes the parameters of the Data Input Dialog of a Surge Arrester.

Surge Arrester – Parameters

Name Name of element. Type Applicable only with a Surge Arrester library. Pressing


Ur Rated voltage in kV. Uc Permanent operating voltage in kV. E Energy absorption capacity in kJ/kVuc. Ures(10kA) Residual Voltage in kV for 10 kA (8/20µs). Ures(1kA) Residual Voltage in kV for 1 kA (30/60µs). I Long-wave capacity 2000µs in A.

Surge arresters are not considered in the calculations.

Surge Arrester - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Surge Arrester - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Surge Arrester - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Measurement Device

This chapter describes the parameters of the Data Input Dialog of a Measurement Device.

Measurement Device – Parameters

Name Name of element. Type Applicable only with a Measurement Device library.


Phase values LM When activating this option, the measurement values may be entered for all three phases independently. In case of symmetrical calculation the phase values for active power will be added and an average value for the current will be taken. If not checked, the total 3-phase active and reactive power and a conductor current may be entered.

P LM Measured total active power in the phases in MW. This value is only relevant when calculating with load balance (see loadflow parameters). If the power flows into the built-in node (see above) the value must be entered as a negative value, if not the value is positive.

Q LM Measured total reactive power in the phases in Mvar. This value is only relevant when calculating with load balance (see loadflow parameters). If the power flows into the built-in node (see above) the value must be entered as a negative value, if not the value is positive.

I LM Measured conductor current in A. This value is only relevant when calculating with load balance (see loadflow parameters). The current value is only considered, when the input fields for the active and reactive power P and Q are set to 0. If the current flows into the built-in node (see above) the value must be entered as a negative value, if not the value is positive.

U Phase voltage in kV, only for information. Use behavior L The module "Load Flow with Load Profiles" uses the

behavior instead of a fixed value.



Delete behavior

L Button to delete the actual behavior.

Show behavior

L Shows the behavior graphically.

Remark The user has to pay attention, that in the network equal measurement data (P, Q or I) exist. If there are unequal measurement data for a region, the loads cannot be balanced.

Measurement Device - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Measurement Device - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Measurement Device - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.



Control Circuit CCT

By entering a Control Circuit CCT-symbol, a new diagram will be opened, where the respective control circuit may be designed, using the function blocks described in chapter Function blocks on page 4-200. There is no difference in the diagrams, used for control circuit (function blocks) entries and network entries. Control circuits (function blocks) and networks could even be entered in the same diagrams. The data input dialog of a CCT-symbol consists only of an Info and a Reliability tab.

Control Circuit CCT - Info The Info tab is described in Element - Info of chapter Data Input Dialogs of Network Elements on page 4-2.

Control Circuit CCT - Reliability The Reliability tab is described in Element - Reliability of chapter Data Input Dialogs of Network Elements on page 4-3.

Control Circuit CCT - User Data The User Data tab is described in Element - User Data of chapter Data Input Dialogs of Network Elements on page 4-3.

General information about control circuits A control circuit is made up of several function blocks. Each control circuit possesses one or more input variables and one or more output variables. An input variable can be any analog or binary variable of the network. An output variable can be:

• the exciter voltage of a synchronous machine • the turbine torque of a synchronous machine • the conductance of a controlled admittance • the susceptance of a controlled admittance



A control circuit can also have more than one output variable for different synchronous machines. Input and output variables are connected to the control circuit concerned by means of input and/or output blocks. Note that an input block turns a variable into a controller signal. A controller signal is an analog or binary output of a control circuit's function block. A controller signal can also be used for outputting on the screen, as a list or in a file. The function blocks of a particular control device are linked to each other via controller signals, this link between the function blocks being "output-controlled". An input of a particular function block is assigned to be an output of another function block, (ie. a controller signal). The identifier of a controller signal consists of the 16 characters of the name of the control circuit and 8 characters of the name of the controller signal.

Initialization of control circuits The starting values of control circuits are determined by blockwise initialization of individual function blocks. Initialization of function blocks takes place from left or right, so long as it is allowed for the particular function block. In most cases initialization with this procedure is successful. If a blockwise initialization of a control circuit is not successful, Prost automatically searches for starting values of those function blocks, which are not yet initialized, to determine them by an iterative procedure. This procedure is based on Newton-Raphson iteration method. Iterative initialization is, however, applicable only to steady transfer functions or transfer functions having no discontinuities. Limits will not be taken into consideration during iterative initialization. After reaching a successful initialization, limits will be checked and limit violations will be reported. Should iterative initialization not yield a solution or starting values come out to be unrealistic, it helps often to specify starting values as input for some of the integrators.



Function blocks

In this chapter all available function blocks to build control circuits are described. Function Blocks, respectively Control Circuits have to be entered in diagrams. There is no difference in the diagrams, used for function block entries and network entries. Function blocks (which build a Control Circuit) and networks could even be entered in the same diagrams. In the following description of the function blocks, the transfer functions are mentioned as well as the initial values, which have to be calculated during the initialization process. For the user, these initial values have only importance, if the initialization process isnt successful. It can help to find out, which variables cant be calculated during the iteration process.

Input Functional description: A control circuit's input interface to other elements. A variable of the network is converted into a controller signal.

u1 y1

Variable Controller signal

Fig. 4.46 Input block

Transfer function Initial value Remark y1 = u1 u1 Iterative initialization permissible

Output Functional description: A control circuit's output interface to other elements. A controller signal is converted into a variable of the network.



u1 y1 Controller signal Variable

Fig. 4.47 Output block

Transfer function Initial value Remark y1 = u1 y1 Iterative initialization permissible

Remarks: The following operands can be specified with an OUTPUT function block: Field voltage of a synchronous machine Turbine shaft power of a synchronous machine Conductance (active component) of a controlled admittance Susceptance (reactive component) of a controlled admittance

Source Functional description: Constant signal source with a value of u0.

K y1 u0

Fig. 4.48 Source block

Transfer function Initial value Remark y1 = u0 u0 Iterative initialization permissible

Network Source Functional description: Constant signal source with a value, which will be taken from the results of the Load flow calculation.



K y1u0LF

Fig. 4.49 Source block

Transfer function Initial value Remark y1 = u0LF u0LF Iterative initialization permissible

The LF value u0LF can be a voltage/voltage angle, current/current angle, active or reactive power of a bus, bus element or branch. This value will always be updated from the Load flow calculation.

Sum Functional description: Sum formation from two input signals u1 and u2 and a constant u0.

u1 y1

u2

K

u0

+

+

+

K

Fig. 4.50 Sum block

Transfer function Initial value Remark 22101 uKuKu = y ⋅+⋅+ 1 u1, u2 or y1 Iterative initialization permissible

Type 0: Type 1: u0 is a constant value u0 is calculated by PROST.

Iterative initialization permissible Impermissible: |K1| or |K2| smaller than 10-8 if corresponding entry is used

Remark: By setting K2 = -1., for example, u2 can be subtracted from u1.



Product Functional description: Product formation from two input signals u1 and u2 and a constant u0.

u1 y1

u2

u0

Π

Fig. 4.51 Product block

Transfer function Initial value Remark 2101 uuu = y ⋅⋅ u1, u2 or y1 Iterative initialization permissible

Type 0: Type 1: u0 is a constant value. u0 is calculated by PROST.

Iterative initialization permissible Impermissible: |u0| smaller than 10-8 if Type 0.

Remark: Initialization is not possible if u1 or u2 < 10-8.

Inverter Functional description: Multiplication of the reciprocal of input variable u1 with a constant K0.

Ku1 f(u1)

y1

Fig. 4.52 Inverter block

Transfer function Initial value Remark



1

01 u

K = y u1 or y1

Iterative initialization permissible.

Impermissible: |K0| smaller than 10-8

Remark: If |u1| is smaller than 10-8: y1 = K0·108·sign(u1)

Ratio Functional description: Division of input variable u1 by input variable u2 and multiplication with a constant K0.

Ku1

f(u1,u2)u2

y1

Fig. 4.53 Ratio block


2

101 u

uK = y ⋅ u1 or u2 or y1

Two of the variables must be given; the third variable is computed.

Iterative initialization permissible


Remark: If |u2| smaller than 10-8: y1 = K0·u1·108·sign(u2)

Gain - Linear Functional description: Multiplication of input variable u1 with a constant K.



K y1u1 K0

Fig. 4.54 Gain block - Linear


101 uK = y ⋅ U1 or y1



Gain - Sectionally linear Functional description: Non-linear function for simulating a sectionally linear relationship with two points of discontinuity.

Ku1 y1

Fig. 4.55 Gain block - Sectionally linear

Transfer function Initial value

Remark

if 0 u ≤1 : 0 y ≤1 if au u ≤1 : 1ao1 uK+K = y ⋅ if b1 a u u <u ≤ : )u-(uK+uK+K = y a1baao1 ⋅⋅ if 1 b u >u : )u-(uK+)u-(uK+uK+K = y b1cabbaao1 ⋅⋅⋅

u1 or y1


Impermissible: |Ka|,|Kb| or |Kc| smaller than 10-8 or larger than 108



Gain - Tabularly non-linear

Functional description: A tabular function f(u) is used as the transfer function. Data are entered into the table in the TAB data block of the Dynamic Data file. The type of interpolation to be used (linear, cubic or Newtonian) is likewise specified there.

u1 y1

Fig. 4.56 Gain block - Tabularly non-linear


( )1ufK y ⋅= 01 u1 ; For strictly monotonously descending or ascending tabular functions, y1 can also be given as the initial value (right-to-left initialization).

Under the mentioned condition on the left, iterative initialization is permissible.

Impermissible: |K0| smaller than 10-8 or larger than 108

Exponential Functional description: Taking the exponent of the input variable u1.

Ku1 f(u1)

y1

Fig. 4.57 Exponential block


12 uK101 eK + K = y ⋅⋅ u1 or y1 ;

If (y1 K0)/K1 < 10-8 : Iterative initialization without limits permissible.



u1 = ln(108)/K2

Impermissible: |K1| or |K2| smaller than 10-8 For initialization with y1 = 0: K0 and K1 not the same sign

Power Functional description: Taking the Kth power of the input variable u1.

Ku1 U1

Ky1

Fig. 4.58 Power block


u = y K11 u1 or y1 Iterative initialization permissible

Impermissible: |K| smaller than 10-4 or greater than 104

Absolute Functional description: Absolute value of input variable

u1 y1

1u

Fig. 4.59 Absolute value block




11 uy = u1 Iterative initialization permissible

Limitation Functional description: Limiting the input variable u1 to a maximum or minimum value, which may also depend on another input variable.

Ku1 1

u2⋅ymax

u2

u3

u3⋅ymin

y1

Fig. 4.60 Limitation


y1 = Minimum(u1,u2·ymax) y1 = Maximum(u1,u3·ymin)

u1 or y1

Iterative initialization without limits permissible

Limitation: The limitation is of the "windup" type. If you want to deactivate the limitation function, you must set ymax and ymin to equal 0. u2 and u3 can be used to simulate dependent limit values. If the limit values concerned are constant, then you must specify blanks for u2 and/or u3.

Rate of change limitation Functional description: Limiting the change of input variable u1 to a maximum or minimum value, which may also depend on another input variable.



K u1 1

u2⋅y’max

u2

u3

u3⋅y’min

y1

Input u1

Output y1

Increase ymax

Decline ymin

Example:

u1, y1

t

Fig. 4.61 Rate of change limitation


see the example given above.

u1 or y1


Limitation: The limitation is of the "windup" type. If you want to deactivate the limitation function, you must set ymax and ymin to equal 0. u2 and u3 can be used to simulate dependent limit values. If the limit values concerned are constant, then you must specify blanks for u2 and/or u3.

Dead band Functional description: Dead band with gain factor.

Ku1 y1

umax

umin

Fig. 4.62 Dead band


101min1

1max1min

101max1

0uKyuu

yuuuuKyuu

⋅=≤=<<

⋅=≥

u1

Iterative initialization not permissible




HV Gate Functional description: The larger of the two input signals, u1 and u2, is switched through to the output. HV gate corresponding to [4].

Ku1

f(u1,u2)u2

y1

Fig. 4.63 HV Gate


if u1 ≥ u2 : y1 = u1 if u1 < u2 : y1 = u2

u1 and u2 ⇔ always possible u1 and y ⇔ only if y > u1 u2 and y ⇔ only if y > u2


LV Gate Functional description: The smaller of the two input signals, u1 and u2, is switched through to the output. LV gate corresponding to [4].

Ku1

f(u1,u2)u2

y1

Fig. 4.64 LV Gate


if u1 ≤ u2 : y1 = u1 if u1 > u2 : y1 = u2

u1 and u2 ⇔ always possible u1 and y ⇔ only if y < u1 u2 and y ⇔ only if y < u2




Coordinate transformation - Polar →→→→ Rectangular Functional description: Converting the variable u1 (magnitude) and the variable u2 (angle in [rad]) into a real and an imaginary part of a complex variable, and multiplying it by a complex constant K.

Ku1

f(u1,u2)u2

y1

y2

Fig. 4.65 Coordinate transformation - Polar → Rectangular


K = K1+j⋅K2 z1 = u1⋅cos(u2) z2 = u1⋅sin(u2) z = z1+j⋅z2 y = y1+j⋅y2 = K⋅z y1 = z1⋅K1-z2⋅K2 y2 = z1⋅K2+z2⋅K1

u1 and u2


Coordinate transformation - Rectangular →→→→ Polar Functional description: Multiplying the variable u1 (real part) and the variable u2 (imaginary part) by the complex constant K and converting the complex result into magnitude and angle (in [rad]).

Ku1

f(u1,u2)u2

y1

y2

Fig. 4.66 Coordinate transformation - Rectangular → Polar




z1 = u1⋅K1-u2⋅K2 z2 = u1⋅K2+u2⋅K1

22

211 z + z = y

1

22 z

z arctan = y

u1 and u2


Excitation - Per Unit Conversion Functional description: No function, kept for compatibility reasons.

K

u1

1y1

Fig. 4.67 Excitation - Per Unit Conversion


11 u = y u1 or y1 Iterative initialization permissible

Excitation - Saturated exciter machine Functional description: Exponential transfer function for simulating the feedback of saturable exciters (KE + SE ) used as per [4] and/or [5].

Ku1 f(u1)

y1



Fig. 4.68 Excitation - Saturated exciter machine


( ) 1ueK + K = y 12 uK101 ⋅⋅ ⋅ u1


Impermissible: |K1| or |K2| smaller than 10-8

Remark: The constants are computed as follows from the parameters stated in [4] and/or [5]:

max max FD

max R0 E

V = ESK −

3max E

4max 0.75 E

1 SS = K

⋅

max 0.75 E

max

max FD2 S

lnE

4 = ESK

Excitation - Static exciter Functional description: Static excitation as per IEC 34-16-1, 1991.

u1

u2

y1Π

f(x)

1

20

uuK ⋅

Fig. 4.69 Excitation - Static exciter


See block diagram above. The non-linear function f(x) corresponds to

u1 and u2




the NLF 2 function block (rectifier regulation characteristic).

Remark: The input and output variables correspond to the following electrical variables of static exciter devices: u1 = VE u2 = IFD y = EFD

Excitation - Rectifier controller Functional description: Non-linear function corresponding to the "rectifier regulation characteristic" in [4].

K

u1 f(u1)y1

Fig. 4.70 Excitation - Rectifier controller


u1 ≤ 0 :y1 = 1 if u1 ≤ (√3)/4 : y1 = 1-(1/√3)⋅u1

if (√3)/4< u1 < 3/4 : y1 = 21u - 3/4

if u1 ≥ 3/4 : y1 = (√3)⋅(1-u1) if u1 ≥ 1 : y1 = 0

u1 or y1


Excitation - Non-continuous controller Functional description: Non-linear function corresponding to Type DC3 in [4].



Ku1

f(u1,u2)u2

y1

Fig. 4.71 Excitation - Non-continuous controller


if u2 > K0 : y1 = YMAX if |u2| ≤ K0 : y1 = u1 if u2 < -K0 : y1 = YMIN

u1 and u2


Static compensators - Firing angle Functional description: Non-linear function for simulating the output of thyristor controls plotted against the firing angle.

Ku1 y1

0 1,0

K0

Fig. 4.72 Static compensators - Firing angle


( )

⋅⋅−⋅= 1101 sin1 uuK y π

π

u1 or y1





Static compensators - Step function Functional description: Step function

Ku1 y1

Fig. 4.73 Static compensators - Step function


( )niKy

nusiu

Kyuuyu

⋅=⋅−≥

=>=<

1max

1

1max1

11 00

u1 Iterative initialization not permissible

Note:

n: Number of intervals of the u-range i: Ongoing interval i = 1...n s: Position of step change 0 ≤ s ≤ 1 0: Step change on the right of the interval 0.5: Step change in the middle of the interval 1: Step change on the left of the interval umax: Range for u1

Impermissible: umax or ymax smaller than +10-8 or larger than +108

The function is defined only for positive umax or ymax

Remarks: For the initialization of u1 from a given y1 the step function is shifted parallel to the y-axis, such that the given y1 value exactly lies on a step.

Integrator

Functional description: Integrator.



u1

f(s)

u2⋅yma

u2

u3

u3⋅ymin

y1y1,0

Fig. 4.74 Integrator


10

1 us

K = y ⋅ y1, an initial value can be given as input.


Limitation: The limitation is of the "non-windup" type. If you want to deactivate the limitation function, you must set ymax and ymin equal to 0. u2 and u3 can be used to simulate dependent limit values.

Time-delay block 1st-order Functional description: 1st-order time-delay block

Ku1 f(s)

u2⋅ymax

u2

u3

u3⋅ymin

y1

Fig. 4.75 Time-delay block 1st-order


1N

01 u

sT + 1K = y ⋅

1 u1 or y1 Iterative initialization without limits

permissible




Derivative block 1st-order Functional description: 1st-order derivative block

Ku1 f(s)

u2⋅ymax

u2

u3

u3⋅ymin

y1

Fig. 4.76 Derivative block 1st-order


1D

D01 u

sT + 1sTK = y ⋅

⋅ u1 Iterative initialization without limits permissible

Limitation: The limitation is of the "windup" type. If you want to deactivate the limitation function, you must set ymax and ymin equal to 0. u2 and u3 can be used to simulate dependent limit values.

Remarks: Time constants smaller than 10-5 will automatically be taken as 10-5

PI controller Functional description: PI controller



Ku1 f(s)

u2⋅ymax

u2

u3

u3⋅ymin

y1

Fig. 4.77 PI controller


1N

Z01 u

sT + 1sT + 1K = y ⋅⋅

u1 or y1



Remarks: If the denominator time constant equals 0, then the Transfer function corresponds to the CONSTANT function block with limitation.

PID controller Functional description: PID controller

Ku1 f(s)

u2⋅ymax

u2

u3

u3⋅ymin

y1



Fig. 4.78 PID controller


1N2N1

Z2Z101 u

)sT+(1)sT+(1)sT+(1)sT+(1K = y ⋅

⋅⋅⋅ u1 or y1



Remarks: Time constants |TN1|, |TN2|, |TZ1| or |TN1-TN2| smaller than 10-5 will automatically be taken as 10-5.

Rational transfer function 2nd-order Functional description: 2nd-order rational transfer function

Ku1 f(s)

u2⋅ymax

u2

u3

u3⋅ymin

y1

Fig. 4.79 Rational transfer function 2nd-order


121o

21o1 u

sa + sa + asb + sb + b = y ⋅

⋅⋅⋅⋅

2

2 u1 or y1


Impermissible:



|a0|, |a2| or |b0| smaller than 10-8. Any value smaller than 10-8 will be taken internally as 10-8.


Rational transfer function 3rd-order Functional description: 3rd-order rational transfer function

Ku1 f(s)

u2⋅ymax

u2

u3

u3⋅ymin

y1

Fig. 4.80 Rational transfer function 3rd-order


1321o

321o1 u

sa + sa + sa + asb + sb + sb + b = y ⋅

⋅⋅⋅⋅⋅⋅

32

32 u1 or y1


Impermissible: |a0|, |a3| or |b0| smaller than 10-8

Any value smaller than 10-8 will be taken internally as 10-8.




Rational transfer function 4th-order Functional description: 4th-order rational transfer function

Ku1 f(s)

u2⋅ymax

u2

u3

u3⋅ymin

y1

Fig. 4.81 Rational transfer function 4th-order


14321o

4321o1 u

sa + sa + sa + sa + asb + sb + sb + sb + b = y ⋅

⋅⋅⋅⋅⋅⋅⋅⋅

432

432 u1 or y1


Impermissible: |a0|, |a4| or |b0| smaller than 10-8

Any value smaller than 10-8 will be taken internally as 10-8. Limitation: The limitation is of the "windup" type. If you want to deactivate the limitation function, you must set ymax and ymin equal to 0. u2 and u3 can be used to simulate dependent limit values.

Binary - Not Functional description: Negation of a binary variable.

y1u1

Fig. 4.82 Binary – Not




y1 = NOT (u1) u1 or y1 Iterative initialization not permissible Remark: A variable or a controller signal is logically TRUE if its numerical value is larger than or equals 0.5.

Binary - And Functional description: "AND" function of two binary variables.

Ku1

f(u1,u2)u2

y1

Fig. 4.83 Binary - And


if u1 and u2: y1 = TRUE otherwise: y1 = FALSE

u1 and u2


Remark: A variable or a controller signal is logically TRUE if its numerical value is larger than or equals 0.5.

Binary - Or Functional description: "OR" function of two binary variables.

Ku1

f(u1,u2)u2

y1

Fig. 4.84 Binary - Or




if u1 or u2: y1 = TRUE otherwise: y1 = FALSE

u1 and u2


Remark: A variable or a controller signal is logically TRUE if its numerical value is larger or equal to 0.5.

Binary - Switch Functional description: Depending on the state of u1, the input signal u2 or u3 is switched through to the output.

Ku1

u2

u3

y1

Fig. 4.85 Binary - Switch


u1 = TRUE y1 = u2 u1 = FALSE y1 = u3

u1, u2 and u3


Remark: A variable or a controller signal is logically TRUE if its numerical value is larger or equal to 0.5.

Rational function 2nd-order Functional description: Rational Function of second order.



u1 y1

211

211

uFuEDuCuBA

⋅+⋅+⋅+⋅+

Fig. 4.86 Rational function 2nd-order


211

211

1 uFuEDuCuBAy

⋅+⋅+⋅+⋅+=

Impermissible: |D| and |E| and |F| < 10-8

u1, y1 Iterative initialization permissible.

Remarks concerning the initialization For a given initial value y1 and |C| or |F| > 10-8 printout of the roots is displayed (see also Error 1). For the calculation of u1 positive root is used. During initialization following error messages may be recorded: a) Given initial value u1 or iterative initialization: Error 0 : 82

11 10uFuED −<⋅+⋅+

Initialization continues with denominator = 10-8 . b) Given initial value y1, if |C| or |F| ≥ 10-8: Error 1 : 0)yDA()yFC(4)yEB( 11

21 <⋅−⋅⋅−⋅−⋅− (Printout of roots)

Error 2 : 81 10yFC −<⋅−

c) Given initial value y1, if |C| and |F| < 10-8: Error 3 : 8

1 10yEB −<⋅− d) Given initial value y1, if |B| and |C| and |E| and |F| < 10-8: Error 4 : 810A −<



IF-THEN-ELSE Switch Functional description: Depending on the value of u1 related to a constant K, u2 or u3 is switched to the output. The operator between u1 and K is selectable.

u2

u1

u3

y1

Fig. 4.87 IF-THEN-ELSE Switch


If u1 # K is true : y1 = u2 Otherwise : y1 = u3 The operator # can be selected as <, ≤, =, ≠, ≥ or >.

u1 Iterative initialization not permissible.

Load Flow


Load Flow

Calculation Parameters (LF)

The calculation parameters are entered with the help of a "Parameters" dialog. It consists of the three tabs, Parameter, References and Area/Zone Control, which are explained here.

Parameter

Calculation method

The Load flow can be calculated according to one of the fol-lowing methods (see Calculation methods and their appli-cation on page 5-14):

• Extended Newton-Raphson method • Current iteration method • Newton-Raphson method • Voltage drop (only for radial networks !)

Calculation with Distributed slack Indicates, whether the load flow should be calculated with

distributed slack or not (see "Calculation with Distributed Slack" on page 5-19).

Area control Indicates, whether the load flow should be calculated with area control or not (see "Area/Zone Control (LF)" on page 5-20).

Wheeling Option for Area control. Option deactivated: The power exchange (calculated from the transactions) takes place only over the elements connect-ing the two network groups (tie elements). Option activated: The power exchange defined for each transaction, can involve other network groups, not participat-ing in the transaction. Wheeling is always allowed when calculating with the Newton Raphson or current iteration method.

Load balance If checked, the load flow will be calculated with load balance. The loads will be adjusted (see "Calculation with Load Bal-ance" on page 5-19).

Load Flow


Set calculated values

Option for Load balance. If checked, the load will be set after a successful load flow calculation with load balance to the calculated value. This is not valid for Load flow with Load pro-file.

Transformer phase shifting

Indicates, whether the phase shifting of transformers should be considered or not. The phase shifting is always consid-ered for asymmetrical load flow. This parameter is not yet valid for Extended Newton Raphson Method.

Autom. trans-former regulation

If checked, the taps of regulated transformers will be auto-matically adjusted to obtain a node voltage Uset in %. If not checked no transformers will be regulated.

Set taps to calcu-lated values

If checked, the actual transformer taps are set to the calcu-lated taps (Tap act = Tap cal).

Asymmetrical network

Indicates, whether the load flow will be calculated with sym-metrical or asymmetrical network structure. If calculating symmetrical load flow, the asymmetrical elements are not considered.

Control generator limits

Indicates, whether the limits of synchronous machines are controlled during LF calculation. If box is not checked, the node type will not be changed during NR iteration (see "Change of node type with Newton-Raphson method").

MW loss sensitiv-ity: MW genera-tion at all nodes

If the checkbox is checked, the change of the network active power losses in respect to a change of active power in the respective node, will be calculated: dSPn=∆Ploss/∆Pn

MW loss sensitiv-ity: MVAR gen-eration at all nodes

If the checkbox is checked, the change of the network active power losses in respect to a change of reactive power in the respective node, will be calculated: dSQn=∆Ploss/∆Qn

Operational fre-quency

Operating frequency in Hz. This value is considered, when a load flow at a different frequency than the nominal system frequency must be performed. The static of the generators are taken into account (see "Synchronous Machine Data" in chapter "Element Data Input and Models").

Result file "" Its possible to write a result file (*.rlf) right after the calcula-

tion. Select the file destination and the file name. This result file can be read by external programs, such as Excel and the results can be evaluated in an arbitrary way.

Write after calcu-lation

Check this option to write the result file right after the calcula-tion.

Format 4.0 The File can be written in the old Format 4.x (checked) or in

Load Flow


a new Format for V5.x (not checked). Iteration data Convergence mismatch:

Convergence criteria for the iteration (see section "Theory of Load Flow Calculation" on page 5-10). Recommended values: 1.0E-3 .. 1.0E-5.

Max. number of iterations:

Maximum number of iterations. If the load flow does not con-verge, the iteration will stop when this number is exceeded.

Check conver-gence

Use of step control, so that the mismatch decreases in every iteration.

Read initialization file

If this box is checked, a previous created file (extension: *.ilf) with the node voltages and transformer taps will be read. In this case the load flow will not be started with U=1.0pu (flat start). The name of the file to be read can be entered.

Write initialization file

If this box is checked, a file (extension: *.ilf) with the node voltages and the calculated transformer taps will be created. The name of the file can be entered.

Current iteration / asymmetrical networks Acceleration fac-tor:

Factor for handling the PV-nodes for current iteration method. The larger the factor, the faster the load flow will converge. The load flow may diverge if a too large value is entered. If there are no PV-nodes, this factor is irrelevant. Possible values: 0.05 .. 0.4. This factor is also used for asymmetrical load flow with cur-rent iteration method as well as for Newton-Raphson method. If the network structure is symmetrical or nearly symmetrical the factor can be set to a value near 1.0. If the network struc-ture is highly asymmetrical it is recommended to take a value of 0.25. or less.

Reference values for loading check Minimum values Maximum values

The user can select, whether the minimal or the maximum rated values of the lines and transformers has to be taken to calculate the loading of these elements.

Switches, circuit breakers and couplers Reduce Check this box to reduce switches, circuit breakers and cou-

plers. The calculation will be faster and the possibility of con-vergence is higher, but no results for these elements will be calculated. If the box is not checked, for calculation, these elements are represented by the impedances entered in the Data Input Dialogs. This option is not available for the calculation method "Ex-tended Newton Rapson". In this case these elements are

Load Flow


modeled without any impedance, so they can't provoke con-vergence problems.

Domestic units P Active power in kW of one domestic unit. This value is used

for loads and line loads. Cos(phi) Cos(phi) of domestic unit. This value is used for loads and

line loads. Kn Interlacing factor for infinite number of domestic units. This

value is used for loads and line loads.

References

Reference for Elements %:

Maximum loading of element in the system (only relevant for evaluation option). Overloaded elements are presented in the Summary of the load flow results.

Minimum Voltage Minimum value for node voltage with respect to nominal sys-tem voltage (only relevant for evaluations). In the table, the reference voltages can be entered individually for each node. Voltages out of limits are presented in the Summary of the load flow results.

Maximum Voltage Maximum value for node voltage with respect to nominal sys-tem voltage (only relevant for evaluations). In the table, the reference voltages can be entered individually for each node. Voltages out of limits are presented in the Summary of the load flow results.

Assign voltages: All

By pressing this button, the default minimum and maximum voltages will be assigned to every node.

Assign voltages: Voltage level

By pressing this button, the voltage level can be chosen, to which the default minimum and maximum voltages will be assigned.

Area/ Zone Control

Control type The user can chose between the following control types: - Area control - Zone control - Area and zone control

Load Flow


Depending on the control type, only the respective power in-terchanges of the table, will be considered for the calculation.

From area To area

For area control, it has to be defined from which to which area the power has to flow. By pressing the "Insert" button, this transaction will be added to the table, where the values may be edited.

From zone To zone

For zone control, it has to be defined from which to which zone the power has to flow. By pressing the "Insert" button, this transaction will be added to the table, where the values may be edited.

Losses taken over by Slack

During Area/Zone Control calculations, losses in the network are taken over by the area or zone which includes the only slack node in the network. As every node is assigned to an area and a zone at the same time, for the control type "Area and zone control", it has to be defined if the area or the zone which includes the slack node, has to take over the network losses.

Table entries Name Name of the transaction. Active Check the box to activate this transaction. Type Type of transaction, Area-Area or Zone-Zone. From MW-power sending area or zone. To MW-power receiving area or zone. Psch MW-power to be transmitted. Tolerance Only for optimal power flow. Maximum deviation from Psch

(Psch Tolerance <= Pexchange <= Psch + Tolerance).

Load Flow


Results (LF)

Select Results The nodes and elements to be presented in the result table, may be selected here. In the menu point Show Results, it can be indicated if all elements and nodes should be presented in the result table or just the ones selected in this ta-ble. Also for the single line diagram there is an option in the Load Flow tab of the Edit Diagram Properties dialog to indicate if the results should be assigned to all elements and nodes or only to those, selected in this Select Results table.

Show Results The results can be represented in different tables, each with its specifique infor-mation.

Summary A summary of the load flow will be displayed. It contains gen-eral information about the network, the areas and the zones and about overloaded elements and nodes with voltages out of the range.

Node results The results of the nodes will be displayed. Element results General results of elements will be displayed. Detailed element results

All results of the elements will be displayed.

All results All results mentioned above will be presented here in one ta-ble.

Units Output units for table list output. The following units are available: V, kV, A, kA, kVA, MVA.

Result files Its possible to export or import results to or from a *.rlf file by selecting the file and pressing the respective button. These result files can be read by external programs, such as Excel and the results can be evaluated in an arbitrary way. The File can be written in the old Format 4.x or in a new Format for V5.x.

Below you find a description of the output variables in the result tables:

Load Flow


Summary:

Area/Zone Indicates the network, area or zone, for which the following results are valid.

P Loss Active power losses in MW, in the network group Q Loss Reactive power losses in Mvar, in the network group. P Imp Total imported active power in MW. The imported active power for

the network represents the total Slack power. Q Imp Total imported reactive power in Mvar. The imported reactive

power for the network represents the total Slack power. P Gen Total generated active power in MW, in the network group, includ-

ing the Slack. Q Gen Total generated reactive power in Mvar, in the network group, in-

cluding the Slack. P Load Total active load power in MW, in the network group. Q Load Total reactive load power in Mvar, in the network group. Qc Shunt Total capacitive reactive power in Mvar, of the shunts in the net-

work group. Ql Shunt Total inductive reactive power in Mvar, of the shunts in the net-

work group. Q Comp Total line compensation reactive power in Mvar, in the network

group. In the summary the nodes, which are lower than the reference voltage UminRef or higher than UmaxRef as well as the overloaded elements are reported. Node results:

ID Identification number (ID) of the node. Name Node name. U [kV] Node voltage (line-earth phasor, but as line-line value) in kV. u [%] Node voltage in % in respect to nominal node voltage. U ang Voltage angle in °, in respect to the slack voltage. Sens. PG Sensitivity of the network MW losses for the node, due to a fictive

change of active power generation in the respective node. dPL/dQP

Sens. QG Sensitivity of the network MW losses for the node, due to a fictive change of reactive power generation in the respective node. dPL/dQG

Description Description of the node.

Load Flow


Zone Zone, the node belongs to. Area Area, the node belongs to. Partial net-work

Number of the partial network, the node belongs to.

Element results:

ID Identification number (ID) of the element. Node name Node, the element is connected to (From Node). Element name Name of the element. Type Type of element. P Active power flow through the element in MW. Q Reactive power flow through the element in Mvar. I Current flow through the element in kA. Angle I Current angle in °. Loading Loading of the element in %. P Loss Active power losses of the element. Q Loss Reactive power losses of the element. P Comp Active line compensation power in MW. Q Comp Reactive line compensation power in Mvar. Tap Calculated tap position of the transformer. Ratio Calculated transformer ratio at "Tap act.". Teta - Angle of the transformer ratio

- Firing angle or inition angle in ° of a HVDC - Firing angel in ° of a TCSC

Overlap Overlap angle in ° for HVDC (Converter). Margin Commutation margin angle in ° for HVDC (Converter) B tot Total susceptance in mS of a SVC. X tot Total reactance in Ohm of a TCSC. U series Voltage drop in kV of a TCSC or Series voltage in kV of a

UPFC. Ang. U series Angle of Voltage drop in ° of a TCSC or Angle of Series volt-

age in ° of a UPFC. I shunt Shunt current in kA of a UPFC. Ang. I shunt Angle of Shunt current in ° of a UPFC. P exch Exchange active power in MW of a UPFC.

Load Flow


Q exch series Exchange reactive power (series-connected inverter) in Mvar of a UPFC.

Q exch shunt Exchange reactive power (shunt-connected inverter) in Mvar of a UPFC.

Slip Slip of Asynchronous Machine. Torque Mechanical torque in Nm of Asynchronous Machine. U OpenEnd In case that an element is connected only on one side, the

voltage is calculated at the open end in %, in respect to the nominal system voltage of the node at the open end.

On Checked, if the element is connected (switches closed). Description Description of the element. Zone Zone, the element belongs to. Area Area, the element belongs to. Partial Network Number of the partial network, the element belongs to.

Load Flow


Theory of Load Flow Calculation

The starting-point of the load flow calculation are - the network equation: I Y U= ⋅ and - the power equation: S U I= ⋅ *.

It means: I: Vector of node currents U: Vector of node voltages Y: Network admittance matrix S: Vector of node powers Eliminating the vector of the node currents in the power equation, it is obvious, that the load flow problem will lead to a quadratic non-linear equation system for the unknown node voltages and given node powers. There are several methods to solve the problem, thus e.g. Gauss-Seidel method, Newton-Raphson method or a fast decoupled method. The methods used in this program are / 1 /

• a current iteration method with the factorised, reduced Y-matrix and • Newton-Raphson method.

Current Iteration Method with the Factorized, Reduced Y-matrix The current iteration method consists of two steps

• Calculation of node currents Ired from the given node powers Sred and the node voltages Ured according to

I red Sred Ured= ⋅ −* * 1 ,

whereby an estimated value is set for Ured in the first iteration step.

• Calculation of the node voltages according to

Ured Yred Ired Ysl U sl= − ⋅ − ⋅1 ( )

It means: Ured: Vector of the complex node voltages without slack nodes Ired: Vector of the complex node currents without slack nodes

Load Flow


Yred: Admittance matrix without row and column of slack node Ysl : Column of slack node in the Y-matrix Usl : Complex slack node voltage

The two iteration steps starts with U=1.0pu or a predefined value (see "Calculation Parameters (LF)" on page 5-1, "initialization file") and are done until the convergence criteria

ε µ µ

µ= + −

=∑

Ui Ui

Uii

n 1

1

is reached (see "Calculation Parameters (LF)" on page 5-1, "Conv.mismatch"). It means Uiµ+1 and Uiµ the voltages of node i in the iteration step (µ+1) res. in the step µ. n represents the number of nodes in the network. If the algorithm diverges, the iteration is stopped after the maximum number of al-lowable iterations. This value is given in the calculation parameters, input field "Max.iteration". PV-nodes require an additional algorithm, which is explained in / 1 /. The speed of this algorithm is dependent on an acceleration factor which can be introduced through the mask of the calculation parameters (input field "Acc.factor").

The Newton-Raphson Method The Newton-Raphson method proceeds from the error equation for the network node i:

∆Si Pi j Qi Ui Yikk

nU k= − ⋅ − ⋅

=∑ ⋅( ) * *

1

The complex voltages Uk have to be found, thus the error ∆Si becomes zero. Pi and Qi are the predefined active and reactive power. Yik is an element of the Y-matrix of the i-th line and k-th column. The solution of above error equation con-sists of three steps:

• Calculation of the power mismatch with the help of the voltages for every node

∆S Svor Sberi i i= −

Load Flow


• Calculation of the voltage variations for every node with the Jacobi-matrix J

∆ ∆U J S= ⋅−1

• Calculation of the node voltages

Uneu Ualt Ui i i= − ⋅α ∆

The two iteration steps starts with U=1.0pu or a predefined value (see "Calculation Parameters (LF)" on page 5-1, "initialization file") and are done until the convergence criteria

ε ==∑ ∆Sii

n

1

is reached (see "Calculation Parameters (LF)" on page 5-1, "Conv.mismatch").

The Extended Newton-Raphson Method The Extended Newton-Raphson method is basically the same as the normal New-ton Rapson method. In the Extended Newton-Rapson method, the modeling equations of the elements are formulated in a different way. Additionally, the FACTS devices and all new features like Area/Zone control are considered by this calculation method.

Differences between Current Iteration Method and Newton-Raphson Method The current iteration method shows in network without PV-nodes and without re-mote control a very good convergence behavior, even in networks with very short lines (small impedances). It is much faster than the Newton-Raphson method. Therefore it should be used when the number of PV-nodes are small (1 to 3). This is the case in medium and low voltage networks. When calculating transmission networks the Newton-Raphson method should be taken. In case of divergence it is possible to start the Newton-Raphson algorithm from a predefined voltage pro-file (see "Calculation Parameters (LF)" on page 5-1). The predefined voltage pro-file could have been calculated with the current iteration method.

Convergence Control with Newton-Raphson Method The coefficient α for the calculation of the new node voltages is normally α = 1 (see third iteration step). If the power mismatch grows from one step to the other, the coefficient will be optimized according to a quadratic interpolation. α is than within the range 0 < α < 1.0.

Load Flow


Change of Node Type with Newton-Raphson Method If the number of iteration is larger than three, the program checks in every itera-tion step, if the voltage of a P,Q-node would be in the range Umin .. Umax (see "Node Data" in chapter "Element Data Input and Models"). This is only valid, if a synchronous machine is connected to that P,Q-node. If the voltage is outside the range the amount of voltage will be fixed. The reactive power will be calculated (change of node type: PQ-node to PV-node). A change of PV-node to PQ-node happens, if a reactive power Q runs out of the range Qmin .. Qmax (see "Syn-chronous Machine Data" in chapter "Element Data Input and Models"). The reac-tive power is fixed and the amount of voltage will be calculated.

Remote Control with Newton-Raphson Method The remote control of transformers and generators are only possible, when cal-culating with the Newton-Raphson method.

Voltage Dependent Loads and Transformer Tap Dependent Short Circuit Voltages In the current iteration method and in the Newton-Raphson method the voltage dependent loads as well as the tap dependent short circuit voltage (see "Trans-former Data" in chapter "Element Data Input and Models") are taken into account during the calculation. The equation for voltage dependent loads are (see "Line Data" in chapter "Element Data Input and Models"):

P = P0 (U/Un)xP Q = Q0 (U/Un)xQ

Load Flow at a Frequency Unequal to the Nominal System Frequency If the operating frequency is unequal the nominal system frequency the generator powers are corrected according to their static (see "Synchronous Machine Data" in chapter "Element Data Input and Models" and "Calculation Parameters (LF)" on page 5-1).

Frequency

Power P

P0

f0

Load Flow


Evaluation in Case of Divergence If one of the above mentioned algorithm does not converge, the program brings a message. The program displays the iteration process and the power mismatch at the nodes. Nodes with large power mismatch are critical nodes. In case of divergence it is also possible to start the algorithm from a prede-fined voltage profile instead of starting from U=1.0pu (flat start). When the node voltages are known, the load flow, the node powers, the losses and the mismatch can be calculated. The mismatch represents a balance of pow-ers and is calculated as follows: Smism = Stot + Sloss + Ssl + Sshunt It means: Stot: Sum of calculated node powers Ssl: Power in the slack node, Sloss: total network losses, Sshunt: total shunt power.

The smaller the value for Smism, the better the load flow has converged.

Calculation methods and their application The application fields for the several calculation methods are: The Extended Newton Raphson should be used in

- Symmetrical transmission networks - Area/Zone control - Facts elements/HVDC - Switched shunts - Remote controls and special controls

The Newton Raphson should be used in - Transmission and distribution networks - Asymmetrical load flow - Load balance - Restricted area/zone control (only with wheeling)

The Current Iteration should be used in - Transmission and distribution networks - Asymmetrical load flow - Only a few PV-generators - Load balance - Restricted area/zone control (only with wheeling)

Load Flow


- No remote control The Voltage Drop should be used in

- Distribution and radial networks with domestic units (house hold)

Load Flow


Voltage Drop Calculation

The voltage drop calculation is only valid for radial networks with one in-feeder (slack node). The total active and reactive load power, inclusive domestic units, in the radial network have to be calculated. The voltage of the neighbor node of the slack node can be calculated with the slack voltage and the total power flow through the line: Slack

S1K1 K2 K3

Sk1 Sk2 Sk320 domestic units+ 20kW

5 domestic units+ 10kW

30 domestic units

S2 S3

UK1 = USl - ZL · S1* / USl

*

with: UK1: Voltage in node K1 USl: Slack voltage S1: Complex power through the line from slack node to node K1

(S1 = SK1 + SK2 + SK3) ZL: Impedance of line

The power seen from node K1 into the network has to be calculated in order to get the voltage at node K2 (S2 = SK2 + SK3). The voltage at K2 can be calculated with the above formula, if exchanging UK1 with UK2 , USl with UK1 and S1 with S2. This procedure is used until all node voltages in the radial network are calculated.

Considering Variable Simultaneity Factors for Domestic Units In the voltage drop calculation the simultaneity or interlacing factors are calculated in function of the number of domestic units nDU according to the following formula

K K Knv n

n

DU

= + −10.

The factor Kn (default value 0.15) can be entered in the load flow parameter mask. The powers used for calculating the voltages consists of two portions:

Load Flow


S = Sconstant + kv · nDU · PDU

For the above example the following powers (PDU = 8 kW) are taken to calculate the voltages (assumption: cos(phi) = 1.0). - Calculation of UK1: S1 = g1 · 20 kW + g2 · 10 kW + 0.265 · 55 · 8 kW - Calculation of UK2: S2 = g2 · 10 kW + 0.294 · 35 · 8 kW - Calculation of UK3: S3 = 0 kW + 0.305 · 30 · 8 kW

PDU and cos(phi) can be entered in the load flow parameter mask. The factors g1 and g2 are constant simultaneity factors, which are entered in the load data mask. The constant powers (20 kW and 10 kW) are multiplied by these factors.

Remark Considering variable simultaneity factors the Kirchhoff current law is not fulfilled. The variable simultaneity factors are not considered when calculating the voltage drops according to Newton-Raphson or current iteration method!

Load Flow


Reference voltages

To each node reference voltages UminRef, UmaxRef can be assigned in percent. To obtain the nodes with voltage outside the range after the calculation click the summary in the result dialog box.

Description of the Results

After the calculation the results are automatically inserted into the single line dia-gram. For every node and element there is a box with results. The box position is predefined by the program. The user can change the position clicking the box and dragging the mouse. The new position will be saved. In the menu option "Edit - Diagram Properties Load Flow Results" the variables to be displayed can be defined, also after the calculation. In the same dialog the user may enable or disable the result boxes.

Load Flow


Contingency (Outage) Analysis

With menu option "Analysis - Contingency Modes" the user can define all ele-ments and nodes (single mode outage) which have to be disconnected during the contingency analysis. Common mode outages can also be defined, that means, that several nodes and/or several elements are disconnected at the same time. Each element or node will be disconnected one-by-one and the load flow will be calculated. In case of a common mode several elements/nodes are disconnected. After the analysis the user can display the results, when selecting menu option Analysis Contingency Analysis Show results. The number of overloaded elements in function of the disconnected node(s)/element(s) is displayed. The worst case is displayed at the top of list. Not only overloaded elements are taken into account, but also all nodes with voltage outside the limits. The limits "Max.loading", "UminRef", "UmaxRef" are entered in the parameter dialog box. Over-loaded CTs and VTs are not considered, but the switches and the couplings.

Calculation with Distributed Slack

If the corresponding parameter is active, the load flow will be calculated with a dis-tributed slack. With this kind of calculation the active slack power will be dis-tributed to predefined synchronous machines. In the input mask of synchronous machines the portion of slack power can be entered. The active slack power can be distributed from 0 to 100%. When calculating with distributed slack only one slack node is possible.

Calculation with Load Balance

If the corresponding calculation parameter is set, the load flow will be calculated with load balance. With this kind of calculation the simultaneity factors of the loads in a closed network are changed in the way that the measured active power or current will be reached. The measured values are entered in a measurement de-vice. The requirements are:

• For a radial network one measurement device is sufficient to get load bal-ance. Normally the measurement device is installed at the beginning of a feeder. In a radial network there can be several measurement devices.

• In closed loop networks there must be at least two measurement devices • In the balanced network there can also be infeed elements, like generators.

Load Flow


• The program can handle any number of radial or closed networks. The net-work between two measurement devices are balanced and a separate simul-taneity factor will be calculated (see above).

• The more measurements in the network, the more accurate will be the load model.

• If the measured values are given per phase, the sum of all powers or an av-erage value for the current will be taken for symmetrical load flow.

• Loads with simultaneity factor zero are not considered during the calculation. • After a successful calculation the simultaneity factor can be set automatically

by the program (see "Calculation Parameters (LF)" on page 5-1). • The accuracy of the load balance can be adjusted with the global conver-

gence criteria. Example:

M e a s u re m e n t d e v ic e

A B

C

1 2

3

In the above feeder the measurement devices 1 and 2 builds section A. All loads in section A will be balanced in order to get the predefined powers or currents in measurement devices 1 and 2. The same is valid for section B and C.

Area/Zone Control (LF)

With the menu option "Calculation - Load flow Parameters Area/Zone Control" the user can enter any number of MW power interchange transactions between network groups (areas, zones). In order to activate power interchange control the user must check the option "Area control" in the Load Flow Parameter mask. The Load Flow calculation module modifies the total generated power per network group, so that the network group power flows (MW) over the tie elements (ele-ments connecting this network group with other groups) satisfy the transactions.

Load Flow


The definition and assignment of zones and areas is explained in detail in the Tu-torial chapter. The following rules hold, when using Area/Zone control:

• All network groups must build an interconnected network. • The user can enable or disable Wheeling: If Wheeling is allowed then the

MW power set in the transaction between network group From and network group To can flow over other network groups. Otherwise only the elements connecting these two groups (if any) carry the scheduled MW power.

• In general there is no hierarchical structure in the definition of areas and zones. Areas can contain more than one zones and vice versa. The only ex-ception is in the case that the Control Type in the Area/Zone Control-tab is set to Area & Zone Control. In this case no area overlapping is allowed for zones (every zone must be contained entirely within one area) or vice versa.

• Only one slack node can be entered in the network. The area (zone) to which the slack node belongs is the Slack Area (Slack Zone).

• An area or zone can fulfill only one of the following tasks at the same time: - working as a Slack Area or Zone - controlling the total import/export (if "Wheeling" is activated) of the net-

work group or controlling the power exchange over a connection between two network groups (if "Wheeling" is not activated).

It's also possible that an area or zone doesn't fulfill any of the tasks above, i.e. it is not controlled.

• For every node, not more than one of the two network groups (area, zone) can be in control mode. It is not allowed for example that the area of node N1 controls MW import and its zone controls an other transaction or works as a Slack network group. In other words, if an area fulfils a task (Control network group or Slack Area), its zones can't have any tasks. If this rule is violated, the user gets a relevant error message.

• For every generator in a network group that is involved in a transaction, a Slack Portion can be defined. It defines the percentage, with which the gen-erator takes part in the import/export power regulation of its network group. The Slack Portions of all generators of a network group are assumed to add up to 100% (see respective field in the Synchronous Machine and Network Feeder Parameters). If all slack portions in a controlled network group are equal to zero, the program assumes equal slack portions for all generators in this group.

The user must be aware of certain differences in the calculation depending on whether "wheeling" is allowed or not.

Load Flow


Wheeling not allowed (option disabled) If Wheeling is not allowed, then the scheduled power flows directly over the tie elements between the two network groups involved in the transaction. If a transaction is entered between network groups that are not directly connected a relevant error message appears. Every network group may fulfill only one task. That means that it can control one power flow transaction between two network groups by controlling the power flow over the tie lines (tie flow) or it's working as a Slack Area/Zone. The tie flows be-tween network groups not involved in a transaction are not controlled. Every con-trolling network group behaves as one variable generation that should satisfy one power interchange between network groups. E.g. if zone control is activated and the network has n zones, there are at most n-1 independent variables that can specify at most n-1 power interchanges between network groups. That imposes a maximum on the number of different transactions that the user can specify. The Load Flow calculation will give an error message if the number of specified con-trols for the network groups (based on the transactions) exceed this maximum limit. The principle of Area/Zone control without wheeling is illustrated in the following example. Example: Schedule:

From To Power in MW Zone 1 Zone 2 150 Zone 1 Zone 2 50 Zone 2 Zone 1 100 Zone 3 Zone 2 50 Zone 3 Zone 4 100

Network with its power flow:

Load Flow


Zone 1 controls T12

Zone 2

Zone 3 controls T32

100MW T12

50MW T32

100MW T34

Zone 4 controls T34

Slack Zone

As you see in the example, several transactions between the same two zones will be added algebraically. The first one of these transactions defines which one of the two zones is the "From network group". During the calculation process, for each transaction a "control network group" will be set. The algorithm is following the order of the schedule table and tries for each transaction to set the "From network group" as the control group for the re-spective power transmission. If the "From network group" has already been as-signed to another task, the "To network group" will be set as the control group. In case that the "To network group" is occupied as well by an other task, a network group which is not involved in a transaction and which is connected to the "From network group" or the "To network group" will take over the control of the power transaction. If such a "free" network group doesn't exist, the Load Flow will not start and the user has to change the transaction definitions (e.g. invert the "From network group" with the "To network group", enter the transaction lines in an other order etc.). Avoid entering transactions with the slack area or slack zone in the From column. This will result in an error of Node: Area and Zone controlled not allowed. The transaction power in the connection lines between two network groups is con-trolled next to the "From network group". If a network group is connected to the Slack network group without transaction be-tween them, then the Slack group will overtake its losses. Otherwise the network group has to take over its own losses. For "Area and Zone control", area overlapping of zones is not allowed. Transac-tions can be entered between two areas or/and between two zones.

Load Flow


Wheeling allowed (option enabled) When wheeling is allowed, the power exchange defined for each transaction, can involve other network groups, not participating in the transaction. That means, that a power flow defined between two network groups doesn't need to be transported over the tie elements between the two network groups. The power can also flow through other network groups. That's why the active power of the generators in the different network groups are set to values that fulfill the import/export values calculated and not the individual transactions. Example: Schedule:

From To Power in MW Zone 1 Zone 2 250 Zone 1 Zone 5 50 Zone 2 Zone 5 100 Zone 3 Zone 1 50

Network with its power flow:

Zone 1 -250MW

Zone 2 150MW + tie losses

Zone 3-50MW Zone 5

150MW

210MW

40MW

90MW 30MW

20MW 20MW

Zone 40MW

Slack Zone

In the example above the transmitted power over the tie elements between two zones doesn't correspond to the transaction defined. Since wheeling is allowed, the power flows can take also other ways than the direct connection. In this case

Load Flow


the total import/export of each network group is controlled to a value that corre-sponds to the defined transactions. With wheeling, also network groups can be involved in the power transmission, which don't participate in the transaction, as it does zone 4 in our example. The power control of each area or zone is working different, if the control type is Area control or Zone control or if it is Area and Zone control. Area control or Zone control All areas (zones) are in Import Control mode apart from the area (zone) that contains the system Slack. That means that all areas (zones) apart from the Slack Area (Slack Zone) control their own import/export power, even those, which are not involved in any transaction. The areas (zones) without any power transactions are controlled to 0MW import/export power. The Slack Area (Zone) takes over the losses in the tie elements. The losses in each network group are taken over by the network group itself. The areas (zones) can extend to more than one zone (area), since the areas and zones are not controlled simultaneously. Area and Zone control In this mode area overlapping of zones is not allowed. Transactions can be en-tered between two areas or/and between two zones. Each network group (areas and zones) involved in the transaction is controlling its import/export power. The import/export power of Areas or Zones without any power transactions is not controlled. The import/export power of Areas containing zones that are involved in a transaction are not controlled as a transaction be-tween zones of different areas could be in conflict with a transaction involving one or both of these areas. The Slack Area or Slack Zone takes over the losses of all tie elements and of the areas/zones which are not controlled. It's up to the user to define whether it's the Slack Area or the Slack Zone that takes over the MW losses (relative option above the transactions table has to be checked).

Load Flow


Asymmetrical Load Flow

If the menu option "Calculation-Load flow-Asymmetrical Load flow" is checked an asymmetrical load flow calculation will be started with "Calculation-Load flow-Calculation" or "Calculation-Load flow-Partial network" or "Calculation-Load flow-Contingency Analysis". The asymmetrical load flow can handle both asymmetrical loads and asymmetri-cal network structure. In the element's input mask there is a field "Phases" were the user can enter the phasing of the element or load. The asymmetrical load flow has the following characteristic.

Theory of Asymmetrical Load Flow The same equations and solution algorithm as for the symmetrical load flow are used. Because of asymmetry the models in the negative and zero system are considered like for short circuit analysis. The Y matrix for the positive, negative and zero system will be created. It is assumed that only the lines, the loads and load impedances are asymmetrical. For these elements there is a coupling be-tween the three component system. These couplings will be considered by node current respectively node power injections / 7 /. The phase shifting are always considered. In the load flow calculation parameter mask there is an acceleration factor. This factor allows to tune the asymmetrical load flow for both methods (Newton-Raph-son and current iteration). If the network is highly asymmetrical the factor should be set to 0.25 or less.

Restrictions of Asymmetrical Load Flow The restriction are: - Area Control not available - Distributed Slack not available - Voltage drop solution method not available - Remote control for generators.

Network Structure for Asymmetrical Load Flow If an asymmetrical load flow will be calculated all elements are considered. In case of a symmetrical load flow only the symmetrical elements and the asymmet-rical 3-phase line are considered. With the menu option "Edit-Topology/Mask-Topology check" the user can check the topology in respect of the symmetrical network or in respect of a single phase. It is recommended to enter lines in a compact way. A 3-phase line from node A to B can theoretically be entered as three single phase lines, which are coupled be-tween each other. In this way the program will work not only with the current cir-

Load Flow


cuit resp. the series impedance matrices but also with the coupling matrices. This increases the calculation effort. The better way is to represent the 3-phase line with one 3-phase line. The same is valid for a 2-phase line.

Output for Asymmetrical Load Flow If an asymmetrical load flow will be calculated the results are displayed and stored for all existing phases.

Load Flow


Load Flow with Load Profiles

Calculation Parameters

Time

1 Load flow cal-culation

The actual time is determined by the fields "Year", "Month", Day" and "Time".

Year Year Month Month Day Day Daytime Time of day Load flow time simulation

The corresponding fields "from" and "to" determine the inter-val for the time simulation.

Year Year range Month Month range Day Day range Daytime Time of day range Time increase Increase in minutes, if field "Time" is active.

It is possible to combine several time ranges ("Year", "Month", "Day", and "Time") in one time simulation. The increase for the ranges "Year", "Month" and "Day" amounts to 1, for the range "Time" it must be determined by the user.

Options

Calculation Apply scaling factors

Determine, if the time-dependent characteristics should be combined with the constant scaling factors.

Results: select nodes / elements All nodes / Ele-ments According to list

Determination if the results of all elements/nodes have to be calculated and stored or if the selection list has to be used.

Edit list... Selection of elements/nodes Results: select variables to be stored

Load Flow


Network: MW losses

If active, active power losses of the network are calculated and stored during a time simulation.

Network: Energy losses

If active, energy losses of the network are calculated and stored during a time simulation. Only possible if the field MW losses is active.

Nodes: U If active, magnitudes of node voltages are calculated and stored during a time simulation.

Elements: P If active, active power of elements is calculated and stored during a time simulation.

Elements: Q If active, reactive power of elements is calculated and stored during a time simulation.

Elements: I If active, current magnitudes of elements are calculated and stored during a time simulation.

Elements: Load-ing

If active, element loadings are calculated and stored during a time simulation.

Result Files It is possible to export the results into a text file if the last calculation was success-ful. Export-file File name File name Build after calcu-lation

If active, the text file is automatically created after a success-ful calculation.

Build Export File The text file is created, if this button is pressed.

Results

Summary A short summary of the last calculation is displayed, if the menu option Calcula-tion Loadflow with Load Profiles Summary... is choosen.

Graphical Results To open the graphical result window choose "Analysis - Load Flow with Load Pro-files Results Charts...".

Load Flow


Subchart settings

Subchart type Select time behavior or value range to be displayed. Add curves manu-ally

If checked, curves have to be added using the tab Curves. If not checked, tab Curves isnt visible and curves of the actual variant are automatically added ac-cording to the following 4 subchart settings.

Variables to be displayed Element type Type of element can be selected Variable Type of variable in function of selected element type can

be chosen. Nodes / Elements to be displayed Select Select if all elements of the selected type are displayed or

only these defined in the list. The list can be defined by pressing push button Edit list.

Axis properties Select axis Select axis whose settings have to be displayed / changed.Title Axis title. Only enabled if the corresponding check box

Automatic is not checked. Resolution Specifies the resolution of the steps in between labels.

Only enabled if the corresponding check box Automatic is not checked.

No of digits Number of label digits. Only enabled if the corresponding check box Automatic is not checked.

Min Sets the axis minimum value. Only enabled if the corre-sponding check box Automatic is not checked.

Max Sets the axis maximum value. Only enabled if the corre-sponding check box Automatic is not checked.

Grid If checked grid lines are displayed. Legend Show legend If checked, legend will be displayed Height Height of legend in % of subchart size

The tab Curves is visible only if Add curves manually is checked. Press the Add Curve button to add a new curve to the subchart. Press the Edit Curve button to change the settings of the selected curve.

Load Flow


Theory The module Load Flow with Load Profiles makes a single load flow calculation (forecast) or a sequence of load flow calculations (time simulation). The active and reactive power of consumers and generators with assigned profile types or measurement data are determined before each load flow calculation. The formula for P(t) and Q(t) can be found in the corresponding element documentation (e.g. synchronous machine).

Optimal Power Flow (OPF, Transmission)



Calculation Parameters (OPF)

The parameters can be entered after having chosen "Calculation - Optimal Power Flow - Parameters". In this dialog box there is also a link to the load flow parameters.

Parameters

Options Slack Bus: Fix V to scheduled value

Fix the bus voltage (complex) to the value given in the slack element(s) dialog(s).

PV Generators: Fix V to scheduled value

Fix the bus voltage magnitude to the values given in the PV generators dialogs.

PV Generators: P Limits: Max, Min

The limits of the active power of the PV Generators are taken from the mask (Pmin..Pmax).

PV Generators: Fix P to to Poper

Fix the active power of PV Generators to the operating value given in the PV generator dialogs.

PV Generators: Relax P by .. %Poper

If the nonnegative r is entered, the active power limits of PV Generators are: (1-r/100)*Poper <= P <= (1+r/100)*Poper

PQ Generators: P,Q Limits: Max, Min

The limits of the active and reactive power of the PQ Generators are taken from the generator dialog (Pmin...Pmax, Qmin…Qmax).

PQ Generators: Fix P,Q to Poper, Qoper

Fix the active and reactive power generation to the operating values given in the PQ generator dialogs.

PQ Generators: Relax P,Q by .. %Poper, Qoper

If the nonnegative r is entered, the limits for the active and reactive power of PQ Generators are: (1-r/100)*Poper <= P <= (1+r/100)*Poper



(1-r/100)*Qoper <= Q <= (1+r/100)*Qoper

HVDC Converters Relax Control by ..%

Indicates the tolerance of the scheduled value for the variable (power, current, voltage) to be regulated by the converter.

Regulating Transformers: Constant tap

Keep the tap of regulating transformers constant to the Tap act value during the optimal power flow.

Regulating Transformers: Relax Controls by..

Indicates the tolerance of the scheduled value for the voltage or power to be regulated by the regulating transformer.

Variable Limits Open Voltage Limits Indicates, whether the node voltage limits Umin and Umax

are checked during the optimization. Open Branch Flow Limits

Indicates, whether the current Irmax or power voltage limits Srmax are checked during the optimization.

Shut down Generators at Pmin

If activated, the program shuts down generators of any type, which produce an active power equal or lower than Pmin.

Shut down PQ-Gen. at Pmin

If activated, the program shuts down generators of the type PQ, which produce an active power equal or lower than Pmin.

Optimal Solution Set Values Indicates, if the optimization results concerning the control

variables of generators and transformers should be assigned.

Discretize Variables If checked, there is a post-optimization step that discretizes all non-continuous variables (taps, switched shunt capacitor-blocks etc.)

Run Load Flow for initialization

Indicates, whether a load flow should start for initialization (recommended).

Calc. Sensitivities of Fobj.

If checked, the sensitivities of the objective functions will be calculated for each node and each line due to a change of active or reactive power in a node or a change of the capacitive reactance of a fictive serial line compensation. The calculated sensitivities are: dFObj/dPGj; dFObj/dQGj; dFObj/dXcj

Solver Solution File



Save It is possible to write a solver solution file (*.osf) right after a successful optimization case. This file can help to provide a good starting point when running similar cases of this network.

Import Before running an optimization case it is possible to import a solver solution file (*.osf) created from a similar case. This will provide a good starting point that will assist convergence. If the created solver solution file (*.osf) is imported in a non-similar case (different options activated) then the user receives a warning that the file was not successfully imported.

LF-Parameters Press this button to enter in the LF-Parameters dialog.

Objective Function

Min/Max Choose if the objective type should be minimized or maximized.

Objective Type Choose the objective type to be optimized. It may be selected one of the following types. - MW Losses - Mvar Losses - Generation costs - MW Import - Mvar Import

Network/Group Choose the network group, which should be optimized with the defined objective function.

Insert By pressing the Insert-button the defined objective function will be added in the table. The table may contain several objective functions, which will be consider in the same optimization process, if the checkbox Active is checked.

Active The objective function will be considered in the optimization process if the checkbox is active.

Weight It's possible to have multi-objective optimization by assigning nonzero weighting factors for the individual objectives. The relative values of the weighting coefficients usually correlate with the relative importance of the individual objectives as well as with their relative magnitude. For example the weighting coefficient of the MW-losses objective is usually larger than the weighting



coefficient of the production-cost objective.

Limits

Default References Loading of Elements Indicates the maximum loading of all elements in the

network. The loading will be checked during the optimization unless the option "Open Branch Flow Limits" in the Parameters tab is checked.

Minimum Voltage Default reference minimum voltage for nodes in the network. This restriction will be checked during the optimization unless the option "Open Voltage Limits" in the Parameters tab is checked.

Maximum Voltage Default reference maximum voltage for nodes in the network. This restriction will be checked during the optimization unless the option "Open Voltage Limits" in the Parameters tab is checked.

Relax Voltage Limits by

Indicates the tolerance in % of the maximum and minimum voltage limits.

Assign Voltages All By pressing this button, the values inserted in the

(reference) Minimum Voltage and Maximum Voltage fields are copied to the corresponding values of all nodes in the table below.

Voltage level After pressing this button, a voltage level of the actual network may be selected. The minimum and maximum voltages of the nodes will then be updated by the reference voltage values.

Remark: In the table below of the Default References, all the nodes are listed, with their minimum and maximum reference voltages. They can also be edited independently.

Setting of the Voltage Bounds If the option OpenVoltageLimits is not active, the voltage bounds at the nodes will be considered during optimization. The upper and lower bounds can be entered individually at each node by opening its input dialog. In the field Usoll the voltage can be fixed to the corresponding



value. If this field remains empty values for a lower and an upper bound of the voltage magnitude can be entered in the fields Umin and Umax. The minimum and maximum values of the node voltages can also be edited in the Limits tab of the optimal power flow calculation parameters dialog. A further possibility to modify the voltage bounds are provided by the input dialogs of the network elements network feeder and synchronous machine. Here the input fields Uoper and Ureg respectively provide the possibility to fix the voltage at the corresponding node. However, this works only if the field Lf-Type is set to PV or SL which corresponds to a voltage regulating element or a slack element respec-tively. This way of initializing a fixed value of a nodal voltage overwrites the one described first. If there is a slack element (SL) and a voltage regulating element (PV) at the same time connected to the same node the fixed voltage defined by the slack element overwrites the fixed voltage of the PV element. These overwrite actions are reported in the log-file.

Setting the Bounds for the Power and Current Flow If the option OpenFlowLimits is not active, the bounds of the power flows and the current flows of the branches can be set in the input dialogs of the corresponding element. The bounds of power flow of the elements will be multiplied with the factor "Loading of Elements" in the Limits tab of the optimal power flow calculation parameters dialog. An upper bound for the maximum current magnitude can be defined for trans-mission lines by writing a value in the input field Ir-max or Ir-min. An empty field means there is no current constraint. Which one of the values from Ir-max or Ir-min will be chosen as the limitation can be selected by activating the correspond-ing check box from the window of the load flow parameters. To define the upper bound for the power flow or the current flow of 2-winding transformers there exits a sub mask Limits of the input mask for 2-winding transformers. It is possible to choose between a constraint of the maximum power flow, a constraint for the maximum current flow or none. Again the selection between one of the values X-max or X-min will be made by activating the corre-sponding check box from the dialog box of the load flow parameters. If the current flow magnitude is limited it is possible to define a value for the primary side of the transformer and one for the secondary side of the transformer. Empty input fields mean there is no upper bound for the flow variables.



Setting the Bounds for the Power Injection in OPF The upper and the lower bound for the injection values of the active and reactive power of generators can be defined in the corresponding input mask for syn-chronous machines. Empty input fields for the upper and the lower limit means, it is not possible to optimize the injection power of the corresponding generator. The values for the active and reactive power of the generator are kept constant. The values are taken from the input fields Poper and Qoper respectively. If the values for the upper and lower bound of the power are defined in the correspond-ing fields Pmin, Pmax, Qmin and Qmax, the OPF can vary them to optimize the objective function.

Setting the Regulated 2-Winding Transformers in OPF To define the bounds for the tap settings of a 2-winding transformer, there is a sub mask TapSettings of the input mask for 2-winding transformer. If the selec-tion Transformer Regulated is set to yes the tap will be set to an optimal position by the OPF, otherwise the tap setting remains constant. Actually there are two OPF runs if there are regulated 2-winding transformers in the input data set. First the tap settings are considered as continuous variables and optimized. For a second run of the OPF they are fixed to the next possible discrete value. The solution of the second run might be not feasible even if the first run converges. In this case the OPF outputs the solution of the first run and prints a warning message to the log-file.

Solver Parameters

Major Iterations If the optimization exits with the message “Too many iterations” then increase this parameter.

Minor Iterations Normally should not be modified. Total Iterations If the optimization exits with the message “Too many

iterations” then increase this parameter.



Results (OPF)

Select Results The nodes and elements to be presented in the result table, may be chosen here. In the menu point “Show Results”, the user can decide by clicking a checkbox, if he wants to see all elements and nodes in the table or only the ones selected here. Also it’s possible to assign the results to every element and node of the network plan, or only to the elements and nodes chosen here. In the menu point Edit – Diagram Properties – Labels, a respective box may be checked.

Show Results The results can be represented in different tables, each with its specifique information.

Summary A summary of the load flow will be displayed. It contains general information about the network, the areas and the zones and about overloaded elements and nodes with voltages out of the range.

Node results The results of the nodes will be displayed. Element results General results of elements will be displayed. Detailed element results

All results of the elements will be displayed.

All results All results mentioned above will be presented here in one table.


Result files It’s possible to export or import results to or from a *.rlf file by selecting the file and pressing the respective button. These result files can be read by external programs, such as Excel and the results can be evaluated in an arbitrary way. The File can be written in the old Format 4.x or in a new Format for V5.x.

Below, the output variables in the result tables are described: Summary:



Area/Zone Indicates the network, area or zone, for which the following results are valid.

P Loss Active power losses in MW, in the network group Q Loss Reactive power losses in Mvar, in the network group. P Imp Total imported active power in MW (total Slack power). Q Imp Total imported reactive power in Mvar (total Slack power). P Gen Total generated active power in MW, in the network group,

including the Slack. Q Gen Total generated reactive power in Mvar, in the network group,

including the Slack. P Load Total active load power in MW, in the network group. Q Load Total reactive load power in Mvar, in the network group. Qc Shunt Total capacitive reactive power in Mvar, of the shunts in the

network group. Ql Shunt Total inductive reactive power in Mvar, of the shunts in the

network group. Q Comp Total line compensation reactive power in Mvar, in the network

group. Node results:

ID Identification number (ID) of the node. Name Node name. U [kV] Node voltage in kV. u [%] Node voltage in % in respect to nominal node voltage. U ang Voltage angle in °, in respect to the slack voltage. Sens. PG Sensitivity of the objective function, due to a fictive change of

active power generation in the respective node. The objective function is defined in the corresponding tab of the calculation parameters.

Sens. QG Sensitivity of the objective function, due to a fictive change of reactive power generation in the respective node. The objective function is defined in the corresponding tab of the calculation parameters.

Description Description of the node. Zone Zone, the node belongs to. Area Area, the node belongs to. Partial network




Element results/ Detailed element results:

ID Identification number (ID) of the element. Node name Node, the element is connected to (From Node). Element name Name of the element. Type Type of element. P Active power flow through the element in MW. Q Reactive power flow through the element in Mvar. I Current flow through the element in kA. Angle I Current angle in °. Loading Loading of the element in %. P Loss Active power losses of the element. Q Loss Reactive power losses of the element. P Comp Active line compensation power in MW. Q Comp Reactive line compensation power in Mvar. Tap Calculated tap position of the transformer. Ratio Calculated transformer ratio at "Tap act.". Sens. Xser Sensitivity of the objective function, due to a change of the

capacitive reactance of the fictive serial compensation. The objective function is defined in the corresponding tab of the calculation parameters. The sensitivity "Sens. Xser" will be calculated for all passive 2-port elements.

Teta - Angle of the transformer ratio - Firing angle or initial angle in ° of a HVDC - Firing angel in ° of a TCSC

Overlap Overlap angle in ° for HVDC (Converter). Margin Commutation margin angle in ° for HVDC (Converter) B tot Total susceptance in mS of a SVC. X tot Total reactance in Ohm of a TCSC. U series Voltage drop in kV of a TCSC or Series voltage in kV of a

UPFC. Ang. U series Angle of Voltage drop in ° of a TCSC or Angle of Series

voltage in ° of a UPFC. I shunt Shunt current in kA of a UPFC. Ang. I shunt Angle of Shunt current in ° of a UPFC.



P exch Exchange active power in MW of a UPFC. Q exch series Exchange reactive power (series-connected inverter) in Mvar

of a UPFC. Q exch shunt Exchange reactive power (shunt-connected inverter) in Mvar

of a UPFC. Slip Slip of Asynchronous Machine. Torque Mechanical torque in Nm of Asynchronous Machine. U OpenEnd In case that an element is connected only on one side, the

voltage is calculated at the open end in %, in respect to the nominal system voltage of the node at the open end.

On Checked, if the element is connected (switches closed). Description Description of the element. Zone Zone, the element belongs to. Area Area, the element belongs to. Partial Network Number of the partial network, the element belongs to.



Description of the Program

The Optimal Power Flow (OPF) problem is formulated as a nonlinearly constrained optimization problem with a scalar nonlinear in general objective function. The load flow (or power flow) calculation (with no optimization) calculates the bus voltages and currents of all network elements, according to a fixed set of values for the power injections and loads, the voltage settings of the PV generators and the tap settings of regulated transformers. There is no degree of freedom in a load flow calculation. In reality, however, the active power injection of a generator is a controllable parameter (control variable) that can be adjusted to meet certain objectives. The consideration of the network control variables as free variables within limits adds additional degrees of freedom to the problem. The optimal power flow will calculate the control variable settings and the network state (complex variables, line currents) that optimize the objective set by the user. The constraints of the OPF consist of

• Linear and nonlinear equality constraints: these are mainly the power flow equations (component modeling equations, Kirchhoff equations etc.) and other network-related equations.

• Linear and nonlinear inequality constraints: Most state and control variables are not allowed to exceed certain limits. These restrictions are represented with this type of operating constraints.

These considerations lead to the following description of the OPF program. The OPF optimizes (minimizes or maximizes) an objective function subject to a set of equality and inequality constraints. The objective function as well as the constraints can be formulated as non linear equations. The OPF is fully integrated into the NEPLAN program environment. The component of the high voltage power system are interfaced like in the power flow calculation. The OPF results are written to result boxes of the graphical user interface of the NEPLAN program as well as in a separate text file. In the following this file will be called the result file.



Objective Function

In the actual program version of the OPF the objective function is - the minimization of the active power losses and - the minimization of the total generation costs. The minimization of the active power losses can be formulated as a sum of the active power losses of the passive network elements. The active power losses of an element is the total of the active power flow which flows into the element. Figure 1 shows the calculation of the losses of a transmission line.

Line

Pij Pji

i j

Plosses = Pij + Pji

Figure 1: Active power losses of a transmission line All elements connecting a bus bar with the earth potential (shunt elements, loads, generators, etc.) and the reduced elements (series and shunt equivalents) are excluded from the objective function. Excluding the network equivalents from the objective function provides the possibility to apply the objective function only to a limited region of the network, which is of interest to the user. To obtain a minimization of the total generator costs a quadratic curve for each generator must be entered. The quadratic curve

with P: active power produced by the generator a: quadratic factor in unit of currency (e.g. US$) to MW2

b: linear factor in unit of currency to MW c: constant factor in unit of currency represents the production costs of a generators. According to these cost curves it will be possible to minimize the generation costs. The factors a, b, c are entered in the dialog boxes of the generators.

cPbPaPC +⋅+⋅= 2)(



Running the OPF Program

The menu command "Calculation - Optimal Power Flow - Calculation" starts the OPF. The optimization might take a few minutes when applied to networks with several hundreds of nodes. After termination the user receives one of the following messages: OPF has found an optimal/near-optimal solution:

• Optimal Solution Found • Near optimal solution found • The current point cannot be improved

An optimal solution has not been found. OPF terminated because:

• The problem is infeasible • The problem is unbounded (or badly scaled) • Too many iterations • The solution has not changed for a large number of iterations • The solver solution file is very ill-conditioned • Error in solver solution file • Contact program developers

In case a first run of the program does not find an optimal solution (and perhaps an infeasible problem is indicated) the upper and lower bounds of the voltages and flows might be set too tight. The user can select between different options for the next trials: The option Open Branch Flow Limits ignores the constraints dealing with the limitation of power flows and current flows of the branches. The option Open Voltage Limits ignores the constraints dealing with the limitations of the nodal voltage magnitude, except the voltage magnitude at slack nodes. Alternatively the user can relax the above mentioned limits by increasing the Loading of elements and/or setting a nonzero Relax Voltage Limits tolerance. After a successful run, the listing can be activated with "Result - List - Last calculation". Similar to the power flow calculation it is possible to calculate a part of the network only. The menu command "Calculation - Optimal Power Flow - Calculation of par-tial network" starts this option.

Short Circuit


Short Circuit

Calculation Parameters (SC)

The calculation parameters are entered with the help of a Parameters dialog. It consists of the three tabs, Parameter, Faulted Nodes, Faulted lines, Special Fault, which are explained here.

Parameter

Fault type Type of fault at faulted nodes. Possible faults are: - 3-phase fault - 1-phase to ground fault - 2-phase fault - 2-phase to ground fault - Special fault - Fault at all existing phases When selecting the option Special fault, the program calcu-lates the fault type, which was predefined by the user. The user can define an arbitrary fault type in the Special fault tab of the Short Circuit Parameters dialog.

Calculation method

Following calculation methods are possible: IEC60909 2001 Calculation of Ik" according to IEC 60909. IEC909 1988 Calculation of Ik" according to IEC 909. Superposition without Loadflow Calculation according to superposition method without pre-fault voltages from the Load flow. The EMF are 1.1*Un. Superposition with Loadflow Calculation according to superposition method with pre-fault voltages from the Load flow. A Load flow calculation will be done before Short circuit calculation. ANSI C37.10 Calculation according to ANSI/IEEE C37.010-1979 will be per-formed. ANSI C37.13 Calculation according to ANSI/IEEE C37.013-1997 will be per-

Short Circuit


formed. This standard calculates the generator current accord-ing to the formula mentioned below.

Ik" max calculation

Indicates, if the maximum short circuit current Ik" (if checked) or minimum short circuit current Ik" (if not checked) should be calculated. The same is valid for the steady state current cal-culation.

Asymmetrical network

If this box is checked, all unsymmetrical elements, like unsym. lines, unsym. transformers, unsym. shunts, etc., are consid-ered in the calculation.

Load flow be-fore Short cir-cuit calculation

This parameter should always be active, when calculating ac-cording to superposition method with load flow. There are cases where no load flow is desired before the short circuit calculation.

Fault distance The fault distance is the distance of a node from a faulted node for which the results should be displayed or saved. A value of "0" means that the results will only be displayed or saved for faulted nodes.

Calculation according to IEC909 Automatic se-lection of c-factor

If the box is checked, the program takes the c-factor according to IEC. Otherwise, the user has to define the c-factor by him-self (see below).

Reduced toler-ance in low voltage system

If checked, a voltage factor c of 1.05 instead of 1.1 will be used for low voltage systems. This option should only be activated if the voltage tolerance of the low voltage system is not higher than +6%. (only for IEC60909 - 2001)

R/X at fault lo-cation for ip branch calcula-tion

If checked, the R/X ratio used for the calculation of the peak short circuit current ip at fault location is also used for the cal-culation of the peak short circuit currents in the branches. If not checked, the branch peak short circuit currents will be calculated with the R/X ratio of the branches and the current ip at fault location will be calculated with its R/X ratio.

Fault duration in s for thermal current calc.

Duration of short circuit in seconds for calculation of thermal short circuit current Ith.

Fault duration in s for DC cur-rent IDC calcu-lation

Duration of short circuit in seconds for calculation of DC-component of short circuit current iDC and of asymmetrical breaking current Iasy.

Time delay of CB in s for breaking cur-rent calc. Ib

Minimum time delay tmin of circuit breakers in seconds. tmin is the shortest time between the beginning of the short circuit and the first contact separation of one pole of the breaker. Possible options are according to IEC: 0.02, 0.05, 0.10, 0.25 s and lar-

Short Circuit


ger. If entering a value in between a linear interpolation will be done. tmin is necessary only for the calculation of the breaking current Ib.

Calculation according to ANSI Number of cy-cles for DC cur-rent IDC calcu-lation

When performing short circuit calculation according to ANSI/IEEE the number of cycles for the calculation of the DC component of the short circuit current can be entered. Typical values are: 3, 4, 5, 8.

Number cycles for breaking current calcula-tion Ib

When performing short circuit calculation according to ANSI/IEEE the interrupting time of the high voltage breakers can be entered. The breaking current Ib will be calculated for this interrupting instant. Typical values are: 3, 4, 5, 8.

E operating Highest operating voltage at all fault locations in pu with re-spect to nominal system voltage. This value is relevant only for calculation according to ANSI/IEEE.

Reduce switches, circuit breakers and couplers Reduce Check this box to reduce switches, circuit breakers and cou-

plers. The calculation will be faster, but no results for these elements will be calculated. If the box is not checked, for calcu-lation, these elements are represented by the impedances en-tered in the Data Input Dialogs.

Result File The result file and its location can be chosen. Write after cal-culation

If checked, the result file will be written after calculation

Format 4.x The result file format of version 5 is different from the format of version 4. Check this box to save anyway in the format of ver-sion 4.x.

Reference for element load-ing

Allowable limit for bus bar and element stress in %. During SC-calculation the CTs/VTs, the protection devices and the switches are evaluated.

Faulted nodes The user can define faults at any nodes in the network. In this tab, the nodes where a short circuit should take place, can be selected from a list of all existing nodes. The type of fault has to be chosen in the Parameter tab.

Short Circuit


Depending on the selected short circuit standard additional data must be entered for a fault location: IEC909: Input of the network type for calculating Ik" (see also "Theory of Short Circuit Cal-culation" on page 9-15). The Network type for Ik"-calculation can be changed in the list of the selected fault nodes. For every fault node, a short circuit calculation will be made. Thats why the network type has to be defined for every fault node. The following network types are possible :

Automatic The program will determine the network type automatically. Meshed The program calculates the short circuit current Ik" in a meshed

network Non meshed The program calculates the short circuit current Ik" in a non-

meshed network. For short circuit calculation in a single-fed network the input "Automatic" should be selected. ANSI/IEEE Input of the interrupting time in cycles of the circuit breakers, which are built in at fault location. This value is used to calculate circuit breaker characteristic factors for the short circuit calculation. The interrupting time will be taken from the input data of the circuit breaker at faulted node. If there is no breaker explicitly built in at faulted node, the interrupting time can be entered respectively changed here. The number of cycles as well as the type of short circuit can be changed in the list of the selected nodes. The following cycles and short circuit types can be entered: Cycles Number Number of cycles. Possible values: 2, 3, 5, 8

Short circuit Automatic: The program determines the type of short circuit: generator

near or generator far fault. Generator near: The program calculates the interrupting current for a

generator near short circuit. The multiplying factor is taken from the tables in fig. 8 and 9 of the ANSI/IEEE standard C37.010-1979.

Generator far: The program calculates the interrupting current for a gen-erator far short circuit. The multiplying factor is taken from the table in fig. 10 of the ANSI/IEEE standard C37.010-

Short Circuit


1979.

Faulted lines The user can define faults on any line in the network. In this tab, the lines where a short circuit should take place, can be selected from a list of all existing lines. The type of fault has to be chosen in the Parameter tab. In the same manner as described for the Faulted nodes, the network type respec-tively the number of cycles for an ANSI/IEEE short circuit calculation has to be en-tered for every faulted line. Additionally the distance in percentage (%) from the "From node" (starting node of line) has to be indicated. At this fault distance, a fic-titious node will be created internally. The whole length of the line is 100%, but the value 100% can not be entered, because this node has already been given as "To node". Analogous is valid for distance 0%. Remark: If a line is faulted, the starting and ending nodes may not be faulted too. In the single line diagram the results of a line fault are attached to the starting or to the ending node depending of the fault distance. In the output listing a line fault is treated as a normal faulted node.

Special fault The "Special fault" tab in the short circuit parameters dialog allows the input of special fault types. The definition of special faults is based on the following idea: Given are at maximum 3 faulted nodes (node 1, node 2, node 3) with each 3 phases L1, L2, L3 (3x3 poles). An additional and independent node is the earth (node 0). The user can connect arbitrary poles through an impedance (Rf, Xf), which can also be zero. It is also possible to connect a pole to earth. Examples are given below. Fault description Insert With this button, a new table line, respectively a new fault defini-

tion may be inserted. An arbitrary number of connections can be entered.

Delete With this button, the marked table lines, respectively fault defini-tions may be deleted.

Export to Li- The fault definitions entered in the table can be exported to a li-

Short Circuit


brary brary. Fault type Arbitrary name of the fault type. If the fault definitions will be im-

ported from a library, the fault type may be chosen, by pressing the button .

Fault de-scription

Description of the fault type.

Table entries From Node Starting node of the connection. Possible values are: "1", "2", "3".Phase From Phase of the starting node of the connection. Possible values

are:"L1", "L2", "L3". To Node Ending node of the connection. Possible values are: "0", "1", "2",

"3". "0" means earth. Phase To Phase of the starting node of the connection. Possible values

are:" ", "L1", "L2", "L3". " " means earth. Rf Real part of the connection impedance between the poles in

Ohm. Xf Imaginary part of the connection impedance between the poles in

Ohm. Assignment of the faulted nodes to network nodes Node 1 Network node, which corresponds to faulted node 1 of the Fault

description. Pressing "" all network nodes are listed. Node 2 Network node, which corresponds to faulted node 2 of the Fault

description. Node 3 Network node, which corresponds to faulted node 3 of the Fault

description. Examples of special fault types with there definition: Fault type A: 1-phase-to-ground fault (phase L3) at node 1 with impedance Zf

Node 1

Zf = 2.0 Ohm

L1L2L3

Fault definition in NEPLAN:

From Phase To Phase Rf Xf Node From Node To Ohm Ohm

Short Circuit


1 L3 0 2.0 0.0 Fault type B: Double earth fault at node 1 (phase L2) and node 2 (phase L3)

Node 1 Node 2L1L2L3



1 L2 0 0.0 0.0 2 L3 0 0.0 0.0

Fault type C: 1-phase fault between all three nodes. The nodes can be from dif-ferent networks and/or from different voltage levels.

Node 1 Node 2L1L2L3

Node 3



1 L1 2 L2 0.0 0.0 2 L2 3 L3 0.0 0.0 3 L3 0 0.0 0.0

Remark 1: If the user will calculate an open conductor series line fault (e.g. phase L1), he must proceed as follows:

Short Circuit


1) Disconnect the line (A to B) at the fault location by inserting two new nodes (H1 H2).

L1L2L3

H 1 H 2L1L2L3

A B

BA

Fault: open conductor

2) Make a load flow calculation with the original line. 2) Perform a short circuit calculation according to the superposition method with

Load flow. The calculation parameter Load flow before Short circuit should be deactivated. The special fault definition is:


1 L2 2 L2 0.0 0.0 1 L3 2 L3 0.0 0.0

The faulted node 1 corresponds to network node H1 and the faulted node 2 to network node H2. When calculating a special fault on a line, a new node has always to be inserted in the line at the moment.

Remark 2: It is advisable to choose the superposition method when performing special faults. In this case the fault voltages are correct.

Short Circuit


Results (SC)

After the calculation the results are automatically inserted into the single line dia-gram. For every node and element there is a box with results. The box position is predefined by the program. The user can change the position clicking the box and dragging the mouse. The new position will be saved. The abbreviations are given below.

Show Results

Fault currents Short circuit results of the nodes and elements in the defined fault distance will be presented.

Currents at fault location

Only short circuit results of the faulted nodes will be pre-sented.

Node voltages Voltages of the faulted nodes are displayed. Result files Its possible to export or import results to or from a file by se-

lecting the file and pressing the respective button. These result files can be read by external programs, such as Excel and the results can be evaluated in an arbitrary way. The File can be written in the old Format 4.x or in a new Format for V5.x.


Results selection The values or quantities, which have to be displayed in the result tables can be selected here.

Below you find a description of the output variables in the result tables: Fault currents and currents at fault location:

ID Identification number (ID) of the faulted node, or of the element for which the fault current is displayed.

Fault location From node

Element/Node at fault location or "From node" of the element, for which the fault data is given.

To node "To node" of the element, for which the fault data is given. Distance from fault

Distance from the fault location to the element, for which the fault data are presented in this row.

Element name

Name of the element, for which the fault data is presented in this row.

Short Circuit


Type Type of element. Un System nominal voltage for nodes. UL-E (RST) Fault voltage (line to earth). (Phase system) Ang U (RST) Angle of fault voltage. (Phase system) Ik'' (RST) Initial short circuit current in the phase system. Ang Ik'' (RST) Angle of Ik'' in the phase system. Ik'' (012) Initial short circuit current in the symmetrical components system.Ang Ik'' (012) Angle of Ik'' in the symmetrical components system. ip: Peak current Ip in magnitude (kA) (Phase system). Not available

when calculating according to ANSI/IEEE. Ib: Breaking current or ANSI interrupting (x cycles) current Ib in

magnitude (kA) (Phase system). Ik: Steady state current or ANSI steady state (30 cycles) current Ik in

magnitude (kA) (Phase system). Ith: Thermal short circuit current Ith in magnitude (kA) of the phases.

Not available when calculating according to ANSI/IEEE. iDC: D.C. component of the short circuit current in magnitude (kA)

(Phase system). Iasy: Asymmetrical breaking current or ANSI asymmetrical 0.5 cycles

current in magnitude (kA) (Phase system). Sk": Short circuit power Sk" (Phase system). Not available when cal-

culating according to ANSI/IEEE. E/Z Symmetrical current according to ANSI/IEEE without considera-

tion of the AC and DC decrement. Not available when calculating according to IEC.

Zf: Network impedance at faulted node in Ohm of positive, negative and zero sequence. Output sequence: Zero, Positive, Negative sequence. In case of symmetrical faults only the impedance of positive sequence is displayed.

Fault type Type of short circuit fault used for the calculation. Method Calculation method (Standard). Maximum current

Indicates the node or the element with the maximum current of one fault calculation.

Network type Type of the network. Calculation according to IEC: - SING.FED: Simple fed sc - MULT.FED: Sc fed from non-meshed sources - MESHED: Sc in meshed network

Short Circuit


Calculation according to ANSI: - GEN.NEAR: Generator near fault - GEN.FAR: Generator far fault

CB delay time Time delay of CB in s for breaking current calculation Ib. SC duration for Ith

Duration of short circuit in s for calculation of thermal short circuit current Ith.

SC duration for Idc

Duration of short circuit in s or in cycles for calculation of DC-component Idc and of asymmetrical breaking current Iasy.

Description Description of the node or the element. Zone Zone to which the element belongs to. Area Area to which the element belongs to. Partial net-work

Partial network to which the element belongs to.

Results only at faulted node Only the currents at fault locations are displayed in the table. ID Identification number (ID) of the faulted node, for which the re-

sults are indicated. Fault location Name of the faulted nodes, for which the results are indicated. Un Nominal system voltage Un in kV of the faulted node .. Selected results

Node-oriented display of the results The results are displayed node oriented. The following blocks are displayed for each faulted node: Block 1: Voltages and currents at faulted node ID Fault

location To node

Distance from fault

Element name

Type Un Results Voltages/ Currents

1236 TWO Faulted 0 65.00 Abbreviations:

ID Identification number (ID) of the faulted node

Short Circuit


Fault location Name of faulted node. To node Faulted. Indicates that the nodes is faulted. Distance Distance from the faulted nodes: 0. Un Nominal system voltage of faulted node in kV. Results Fault currents and voltages at faulted nodes.

Block 2: Results in the elements connected with the faulted node ID From

node To node

Distance from fault

Element name

Type Un Results Cur-rents

1374 TWO ONE TRA1-2 2W Tra 1300 TWO THREE LIN2-3 Line Abbreviations:

ID Identification number (ID) of the element connected with the faulted node.

From node Name of From node (faulted node). To node Name of To node. Element name

Name of the element.

Type Type of the element, e.g. line, 2W-Transformer, generator, Results Currents, which flows from From node to To node caused by

the fault in node of block 1. Block3: Voltages at nodes, which are connected through elements with the faulted node ID From

Node To node

Distance from fault

Element name

Type Un Results Voltages

1236 ONE 1 220.00

Abbreviations:

ID Identification number (ID) of the node, which is connected through elements with the faulted node.

From node Name of the node, which is connected through elements with the faulted node.

Short Circuit


Distance Gives the distance of the node in respect of the faulted node. Un Nominal system voltage of the node in kV, which is connected

through elements with the faulted node. Block 4: Results in the elements connected with the node of block 3 ID From

node To node

Distance from fault

Element name

Type Un Results Cur-rents

1374 ONE TWO TRA1-2 2W Tra

1400 ONE SIX LIN1-6 Line Abbreviations:

ID Identification number (ID) of the elements, which are connected with the node of block3.

From node Name of From node. To node Name of To node. Element name

Name of the element.

Type Type of the element, e.g. line, 2W-Transformer, generator, Results Currents, which flows from From node to To node caused by

the fault in node of block 1. Blocks 1 and 2 are always displayed. The number of blocks 3 and 4 depends on the Fault Distance entered in the Calculation Parameters. Node voltages:

ID Identification number (ID) of node, for which the voltages are in-dicated.

Name Name of node. Faulted Indicates the faulted node. Un System nominal voltage of node. UL-E (RST) Fault voltage (line to earth). (Phase system) Ang U L-E (RST)

Angle of fault voltage (line to earth). (Phase system)

UL-L (RST) Fault voltage (line to line). (Phase system)

Short Circuit


Ang U L-L (RST)

Angle of fault voltage (line to line). (Phase system)

U (012) Fault voltage (symmetrical components system). Ang U (012) Angle of fault voltage (symmetrical components system). U0 Pre-fault voltage, may depend on the load flow. If the calculation

is performed according to IEC or ANSI/IEEE the pre-fault volt-ages are zero

Ang U0 Angle of pre-fault voltage, may depend on load flow. Fault type Type of short circuit fault used for the calculation. Method Calculation method (Standard). Maximum current

Indicates the node with the maximum current of one fault calcula-tion.

Description Description of the node. Zone Zone to which the node belongs to. Area Area to which the node belongs to. Partial net-work

Partial network to which the node belongs to.

For asymmetrical faults all results (phases L1, L2, L3) can be displayed, for sym-metrical faults only results of phase L1 are displayed. Phase-to-phase voltages are calculated as:

UL1,L2 = UL2 - UL1 UL2,L3 = UL3 - UL2 UL3,L1 = UL1 - UL3

The output sequence is UL1,L2, UL2,L3 and UL3,L1. Only the voltages of the 0.5 cycles network will be reported when calculat-ing according to ANSI/IEEE.

Short Circuit


Theory of Short Circuit Calculation

The behavior of a power system during short circuit can be represented by a net-work equivalent consisting of a prefault voltage source U0k and the network im-pedance Zkki for the positive, negative and zero sequence system at the faulted node. The infeed elements such as network feeders, generators and asynchro-nous motors are modeled by an impedance Ze and their source voltage (EMF). During calculation they will be changed to equivalent current sources. Assuming symmetrical structure and supplying of the power system the symmetri-cal components are only interconnected at the fault location. The interconnection will be defined by the fault equations. The equations are dependent on the fault type: - 3-phases short circuit:

1

01 Zk

kU"Ik =

02 ="Ik

00 ="Ik

- 1-phase to ground short circuit:

021

01 ZkZkZk

kU"Ik++

=

"Ik"Ik 12 =

"Ik"Ik 10 =

- 2-phases short circuit:

21

01 ZkZk

kU"Ik+

=

Short Circuit


"Ik"Ik 12 −=

00 ="Ik

- 2-phases to ground short circuit:

( )( ) 02021

0201 ZkZkZkZkZk

ZkZkkU"Ik⋅++⋅

+⋅=

02

012 ZkZk

Zk"Ik"Ik+

⋅−=

02

210 ZkZk

Zk"Ik"Ik+

⋅−=

It means: U0k: Operating voltage or prefault voltage at faulted node k. Zkki: Network impedance at faulted node of positive (i=1), negative (i=2) and

zero (i=0) sequence system. Iki": Initial short circuit current at faulted node of positive (i=1), negative (i=2)

and zero (i=0) sequence system. Depending on the calculation method the prefault voltage U0k will be

calculated with the help of current sources res. the currents of infeed elements Ie (superposition method)

set per definition (IEC909, ANSI/IEEE). The currents of the infeed elements Ie for the superposition method are calculated as Ie = EMF / Ze. Ze is the internal impedance of infeed elements. The prefault voltages U0 may be calculated from the network equation U = Y-1 · Ie. The pre-fault voltage of the node k is U0k. The internal voltage (EMF) of the infeed ele-ments are

of the node's nominal system voltage as a set value (the parameter "calculation method" must be set to "superposition without LF") or

calculated from the load flow results. The calculation will be done with the help of the complex voltages and powers at the nodes. The load flow calculation must have been calculated before and the parameter "calculation method" must have been set to "superposition with LF".

Short Circuit


The IEC909 method set the prefault voltage at faulted node per definition to U0k=c·Un, whereby the currents of infeed elements Ie are set to zero. The voltage factor c is dependent on the nominal system voltage at fault location and is de-fined by the standard. The factor c will be set automatically by the program. The ANSI/IEEE method set the prefault voltage at faulted node per definition to U0k= Eoper and the currents of infeed elements Ie are set to zero. The value Eoper is an input value (see "Calculation Parameters (SC)" on page 9-1) and is the highest operating voltage in pu at fault location. For calculating the interrupting duty of a breaker the current will be multiplied by a factor, which is a function of the X/R ratio at fault location. The network impedances Zkk1, Zkk2 and Zkk0 can be computed from the net-work equations U = Y-1I of positive, negative and zero sequence system. Depending of the used method the Y-matrix looks different:

All elements are considered in the calculation according to the superposition method. The models are described in section Element data input and de-scription of the models.

The IEC method prescribes to neglect all shunt admittances of the positive se-quence system. Additionally the impedances of the infeed elements will be corrected (see "Synchronous Machine Data", "Asynchronous Machine Data", etc. in chapter "Element Data Input and Models").

The ANSI/IEEE-standard tells that there must be built up three different Y-matrices for the positive system in order to be able to calculate the currents Ik" (0.5 cycles), Ia (x cycles) and Ik (30 cycles). The impedances of the gen-erators and motors must be corrected for all three matrices. In section 5.4.1 of ANSI/IEEE C37.010-1979 these factors are described. The loads are ne-glected. The impedances of the negative and zero system will not be cor-rected. For getting the X/R-ratio two separate nodal admittance matrices (positive and zero system) with only the resistive part of the network were built up.

Typical quantities of the short circuit current are the peak current, the breaking current, the steady state current and the thermal current. The IEC or ANSI/IEEE gives the method how to calculate these quantities from the initial short circuit cur-rent.

A Comparison of the Methods: The superposition method is the more accurate method assuming that the prefault voltages are known. It is difficult to know the voltages before short circuit espe-

Short Circuit


cially in a planning state, where the load flow can only be approximated. Moreover the load flow which will lead either to a maximum or to a minimum short circuit current at the different locations of the system is hard to find. This module provides a simplified superposition method. The internal voltage sources (EMF) are set to 110% of the nominal system voltage of the infeed ele-ments. Thereby a voltage drop of 10% between the terminal voltage and the in-ternal voltage is assumed for normal operating. For the exact superposition method a load flow has to be calculated before calculating the short circuit. The IEC or ANSI/IEEE method is a simplified method which can be used to calcu-late short circuit currents. It has the advantage that the prefault voltages have not to be known to get accurate results. The calculated currents are on the safety side. The calculation is performed according to an international standard. It is advisable to calculate the short circuit currents according to the IEC or ANSI/IEEE method, especially when the peak currents, the breaking cur-rents and the steady state currents should be calculated. To calculate the voltages during short circuit (post fault voltages) the superposition method should be used.

Network Type IEC For the calculation according to IEC the supply of the short circuit is of impor-tance:

Simple fed short circuit: The short circuit is supplied by only one network feeder or one generator or identical parallel generators (see fig. 9.1). The current at fault location corre-sponds to the current of the infeed element.

Short circuit fed from non-meshed sources: The short circuit is supplied parallel by several active elements (see fig. 9.2). The current at fault location is calculated as the sum of the partial currents. The size of the partial currents are independent of each other.

Short circuit fed from non-meshed sources over a common impedance: The short circuit is supplied by several active elements over a common im-pedance (see fig. 9.3). The current at fault location is calculated as a super-position of the partial currents (see point d).

Short circuit in an intermeshed network: The short circuit is supplied by several active elements in an intermeshed network (see fig. 9.4). The current at fault location is calculated as a super-position of the partial currents.

Short Circuit


G3 ~ F

Fig. 9.1 Simple fed short circuit

Q B

F

G3~

M3~

Fig. 9.2 Short circuit fed from non-meshed sources

Q B

F

Z~

G3~

M3~

Fig. 9.3 Short circuit from non-meshed sources over a common impedance

M3~

M3~

M3~

G3~

F

Q

Fig. 9.4 Short circuit in an intermeshed network

Short Circuit


For the calculation of the initial short circuit current Ik" and of the peak current Ip the results are independent of the network type.

The Initial Short Circuit Current Ik" This current will be calculated according to IEC or the superposition method. The fault currents in the phases are calculated by desymmetrizing the currents in the component system. With the module Short circuit the minimum and maximum ini-tial short circuit current Ik"min res. Ik"max can be computed. The selection is made in the dialog of the calculation parameters, field "Ik"maximal" (see "Calculation Parameters (SC)" on page 9-1). The user gets the maximum initial current when the parameter is set to "YES", otherwise the minimum current is computed. In this case the minimum short circuit power of all network feeder are taken, the asynchronous machines are neglected and the resistance of the lines are taken by increased temperature.

The Initial Short Circuit Power Sk" The initial short circuit power is calculated dependent on the kind of fault: symmetrical fault: Sk Un Ik" "= ⋅ ⋅3

asymmetrical and special fault: Sk Un Ik" " /= ⋅ 3 Un means the nominal system voltage.

The Peak Short Circuit Current Ip The peak current Ip is the highest possible instantaneous value of the short circuit current and is dependent on the ratio R/X. It can be calculated according to IEC as:

"Ikip ⋅⋅= 2κ

with kappa = 1.02 + 0.98·e-3·R/X. To compute the ratio R/X the method of the equivalent frequency is used, that means that the following term is used R/X=Rc/Xc·(fc/f). Rc and Xc are the equiva-lent resistance and reactance at fault location with the equivalent frequency fc. Zc=Rc+j·2·Pi·fc·Lc is the impedance as seen from the fault location if an equiva-lent voltage source as the only active voltage is applied with the frequency fc=20Hz (for f=50Hz system frequency) or fc=24Hz (for 60Hz system frequency).

Short Circuit


To compute the branch currents the ratio R/X of the branches or the ratio R/X at fault location are used, depending on the Calculation Parameter entry. When calculating special faults (e.g. double earth faults) the factor kappa is calcu-lated in the same way as for symmetrical 3-phase short circuits and if several faulted nodes are involved, the largest kappa-value is taken.

The Short Circuit Breaking Current Ib The breaking current Ib for a synchronous machine will be calculated as:

"IkIb ⋅= µ

The factor µ (mue) will be calculated according to IEC and is a function of the ratio Ik"/IrG and of the minimum time delay tmin of the circuit breakers (Ik": initial short circuit current; IrG: rated current). The minimum time delay is an input value and will be introduced in the dialog of the calculation parameters (see "Calculation Parameters (SC)" on page 9-1). For motors the breaking current Ib is

"IkqIb ⋅⋅= µ

The factor µ can be computed analogous to above. The factor q is a function of the ratio m=P/p (P: rated resistive power; p: number of pole pairs) and of the minimum time delay of the breakers. Depending on the network type the breaking current at fault location is computed as: - SC in a meshed network:

( )

∑ ⋅

⋅−⋅∆−∑ ⋅−⋅∆⋅

⋅−=

j"jIkMjqj

"jUM

i"iIkGi

"iUG

Unc"IkIb µµ 113

with c·Un/√3: Equivalent voltage source at fault location Ik": Initial short circuit current ∆UG"i, ∆UM"j: Initial voltage differences at the connection point of synchro-

nous machine i and of asynchronous machine j IkG"i, IkM"j: Initial short circuit currents of synchronous machine i and

asynchronous machine j

Short Circuit


- SC fed from non-meshed sources:

∑=i

iIbIb

Ibi represents the breaking current of the active element i, which is connected to the faulted node. - Single fed SC:

iIbIb =

Ibi represents the breaking current of the active element i, which is connected to the faulted node. When calculating asymmetrical and special faults it is set: Ib = Ik". Remark: The type of network is determined by the program.

The Steady State Current Ik The steady state current will be computed dependent on the type of network:

SC in a meshed network: Ik at faulted node: Ik Ik OM= " , Ik"OM is the initial short circuit current without considering the motors

SC fed from non-meshed sources: Ik at faulted node: Ik Iki

i

=∑ ,

Iki is the steady state current of the element i which is connected to the faulted node.

Simple fed short circuit: Ik at faulted node: Ik Iki= Iki is the steady state current of the element i which is connected to the faulted node.

When calculating asymmetrical and special faults it is set: Ib = Ik". The steady state current of a synchronous machine Ik will be calculated for a sin-gle fed network as:

Ik IrG= ⋅λ

The factor lambda is a function of Xdsaturated, Ufmax/Ufr, Ik"/IrG and the type of machine (turbo or salient pole). These parameters are input values, except the ini-tial sc current Ik" (see "Synchronous Machine Data" in chapter "Element Data In-put and Models"). IrG is the rated current of the machine. A minimum or a maxi-

Short Circuit


mum λ-factor can be calculated. Depending on the input in the field "Ik"maximum" of the calculation parameter dialog the minimum res. maximum initial short circuit current and the steady state current are calculated. For calculation of the minimum steady state current compound excited generators are treated different.

The Thermal Short Circuit Current Ith The thermal short circuit current Ith is calculated as:

nm"IkIth +⋅=

The factor m takes into account the thermal influence of the aperiodic component of short circuit current and the factor n the thermal influence of the alternating component of short circuit current. The factor m is a function of kappa and short circuit duration Tks. The factor n is a function of ratio Ik"/Ik, factor kappa and short circuit duration (see "Calculation Parameters (SC)" on page 9-1, input field "Tshort Ith").

The D.C. Component of Short Circuit Current iDC The D.C. component of the short circuit power is calculated as:

X/Rtfe"IkDCi ⋅⋅−⋅⋅= π22

with f as frequency, t as short circuit duration and R/X as ratio of real- to imaginary part of the impedance. The R/X-ratio is calculated according to the equivalent fre-quency method (see above, calculation of peak current Ip). The short circuit dura-tion t is input value, input field "Tshort iDC" (see "Calculation Parameters (SC)" on page 9-1). When calculating special faults (e.g. double earth faults) the factor R/X is calcu-lated in the same way as for symmetrical 3-phase short circuits and if several faulted nodes are involved, the smallest R/X-value is taken.

The Asymmetrical Breaking Current Iasy The asymmetrical breaking current is calculated according to:

22DCiIbasyI +=

with Ib: breaking current and iDC: D.C. component of short circuit current.

Short Circuit


The ANSI/IEEE-currents According to ANSI/IEEE the currents are calculated in order to be able to select a circuit breakers. There are three different currents:

Symmetrical 0.5 cycles current Ik" Asymmetrical 0.5 cycles current Iasy Symmetrical x cycles (interrupting) current Ia (x: input value, e.g. 3, 4, 5, 8) Steady state (30 cycles) current Ik

For all three times (0.5, x, 30 cycles) a separate network must be built up. All fault voltage are reported for the 0.5 cycles network.

The symmetrical 0.5 cycles current The current will be calculated as follows (3 phase sc):

11 Zk

operE"Ik =

The impedance at fault location Zk1 will be found from the complex Y-matrix of the positive system. The Y-matrix is different than the one of IEC909.

The asymmetrical 0.5 cycle current The current will be calculated as follows (3 phase sc):

X/RX/Rtf e.ZkoperE

e.ZkoperE

"Iasy ⋅⋅−⋅⋅⋅⋅− ⋅+∗=⋅+∗= ππ 24 2011

2011

1

The impedance at fault location Zk1 will be found from the complex Y-matrix of the positive system same as for Ik". The X/R ratio will also be found from the Y-matrix. f is the network frequency, t = 0.5 / f the time.

The symmetrical interrupting current (x cycles current) The current will be calculated as follows (3 phase sc):

1ZkioperE

fIa SC •=

The impedance at fault location Zki1 will be found from the complex Y-matrix of the positive system, which is different to that one for calculating Ik". The factor fSC will be calculated with the help of X/R- resp. Zki1/R-ratio, the type of network

Short Circuit


(generator near or far) and the type of short circuit (symmetrical or asymmetrical fault). The value for the resistance R will be found from a separate Y-matrix, which contains only the resistive part of the network. The value for fSC can be found from figures 8, 9 and 10 of ANSI-standard C37.010-1979. The program reports the value E/Z as well:

1ZkioperE

Ia =

The symmetrical steady state (30 cycles) current The current will be calculated as follows (3 phase sc):

1ZkkoperE

Ik =

The impedance at fault location Zkk1 will be found from the complex Y-matrix of the positive system, which is different to that one for calculating Ik" and Ia.

ANSI Standard C37.013 In this Standard, the short circuit calculation is carried out, concerning the genera-tors in the network with there current. These currents are calculated by the follow-ing formulas: Generator source symmetrical short-circuit current

+

−+

−

⋅= −−

d

T/t

d'd

T/t'd

''d

rms_sym_source_gen Xe

XXe

XXVPI

'd

''d

111113

Generator source asymmetrical short-circuit current

−⋅

+

−+

−

⋅⋅= −−− a

'd

''d T/t

''dd

T/t

d'd

T/t'd

''d

asym_source_gen eX

tcosX

eXX

eXXV

PI 11111132 ω

With P = rated power, V= rated maximum voltage and the reactance values of the generator in pu.

Short Circuit


Short Circuit


Calculation of Partial Networks (SC)

In case of a large network, which consists of several partial networks, it is possible to select the partial network(s) to be calculated. A partial network is a network, which is not connected to an other network, because of e.g. open lines. The pro-gram displays all partial networks in a list box and the user can select the net-work(s) to be calculated. Making the calculation with only a part of a large network has the advantage of saving a lot of computing time.

Selectivity Analysis



The selectivity module

Installation The following files belong to the selectivity module: Program files : D_SelModul.exe German program version E_SelModul.exe English program version SelDevic.dll Protection devices SelInter.dll Interface to the interactive graphic Mfc42d.dll, Msvcrtd.dll

Microsoft program libraries

Mcontr32.dll Control functions Libraries : *.sd1 Characteristics *.sd2 Protective modules *.sd3 Protection devices Project files : *.sel Protection devices and diagrams

Functions of the independent E_SelModul.exe module The program contains the following components/functions:

• Editor for characteristic libraries (*.sd1) • Editor for protection module libraries (*.sd2) • Editor for protection devices libraries (*.sd3) • Editor for protection project files (*.sel) with protection devices and selectivity

diagrams • All objects can be documented in page view and printing.



The program registers itself in the registry the first time it is launched. This permits standard Explorer features to be used such as double-clicking on files to open, file dragging, and opening or printing files from the Explorer context menu. A file format change was required; files created with the previous module (up to version 4.1) can be read and edited. Back conversion is not possible without a partial loss of data. The customary file backup mechanism has been implemented: existing files are saved with a modified extension (*.s_1 or *.s_2 ...).

Functions of the interactive graphic E_E32.exe The program loads the protection device file (*.sel) with the project data (*.mcb), if available, i.e. if both files have the same name. The following functions are available:

• Editing of protection device data with the graphic or list editor • Editing of selectivity diagrams with the list editor • Simulation of the response characteristics in short-circuit and load flow

calculations; the response time is documented in the graphic.

• Automatic creation of selectivity diagrams according to calculations



General

The user interface and handling of the program corresponds to current standards. Launching the program does not create a new empty document as in Word or Excel, for example. The user uses the menu to determine the type of library (characteristics, protection modules...) or the project file to be created/opened. Multiple files (*.sd1, *.sd2...) can be opened and edited; files can also be merged. Access to the contents of the file is realized via the list of elements; double-clicking on an element opens the editing dialog. If different file types are to be associated, for example to transfer characteristics to modules, the "?" function always applies to the library that last had the focus. For users, this means that they must open and focus on the required library in time when entering data (before inserting the new element).

The menus and icons Actions are performed using menus and a tool bar. Both are self-explanatory as they correspond to standards and feature "ScreenTips", i.e. bubble help and explanations in the status bar. Context menus can be accessed via the right mouse button in many dialog fields.

The list of elements The contents of the open file are displayed in a list field. A variety of views are available in a manner similar to that of the Explorer. See "View" menu and tool bar. An icon containing information about the type of device belongs to each element in the list. One or more elements can be selected in the list; the action is then selected via the menu or tool bar. If multiple elements have been selected for editing, the data masks will appear consecutively. The selection of specific elements for documentation is also possible. In the case of libraries, the type name and an optional description appears in the list. This information can be entered in the data mask after clicking the "Type Info" button. The type name may have up to 24 characters, the description up to 64 characters. Descriptions are not available in old libraries. Topological information and the device type appears in the list for the protection devices of a project file.



System parameters The system parameters that are stored in a user-specific manner in the registry include the user ID for the table header and the settings of folders for data and libraries. The dialog is opened via the "Tools – System Parameters..." menu.

Project information Each project file contains project-specific information which is important for the documentation. The dialog is opened via the "Tools – Project Information..." menu.

The table header can be taken over from the system parameters with the "read in" button. The following output languages are currently available: German - with decimal comma



German (CH) - with decimal point English French

Integration in the interactive graphic

General The selectivity analysis module must be enabled for access to the "advanced" protection device data; see "Info – Modules..." and activation of the menu option "Calculation – Current-Time Protection". The protection device data is stored in a separate file with the extension *.sel. The program automatically loads this file together with the project data (*.mcb). This requires both files to have the same name. The data is associated through the unambiguous element name and an internal ID. The protection device data that was previously managed separately (up to V4.1) can be used without changes. Preparatory processing with the SelModul may be necessary to update the protection device data.

Editing of protection device data Access to the "advanced" protection device data is realized via the standard data mask and the "Characteristic" button. The dialog field for advanced data is then displayed.



Alternatively, a list of protection devices can also be used for access. The list can be called up using the "Calculation –Time Overcurrent Protection – Protection Devices..." menu. This list contains all protection devices, i.e. also those that are not shown in the graphic.

The data can be accessed with a double-click.



Protection device response The response of protection devices is always checked in short-circuit and load flow calculations. The response time is shown in the graphic, provided

• the device responds and • is visible.

The basis for determining the response time from the characteristic is the branch-circuit current in the branch to which the protection device is assigned. After the calculation, this current is also shown in the protection device dialog. As a rule, short-circuit current calculations should be made with only one fault location and large fault distance !

Creating selectivity diagrams After a short-circuit calculation has been performed, the program can create a selectivity diagram in which all protection devices affected by the projected fault are shown with their characteristics. A diagram can also be created after a load flow calculation, but the short-circuit current calculation generally provides the better results. To create a diagram, use the "Calculation – Current-Time Protection – Evaluation Last Calculation..." menu. A diagram with the following contents will appear:

(1) All affected protection devices (2) The characteristics of these protection devices (3) The currents "measured" by the protection devices



(4) The identification of the currents in the diagram

The decision as to whether a protection device is included in the diagram is based on the number of protection devices found:

1. Initially all protection devices that have registered more than half the nominal current are included

2. If more than 10 devices were found in step 1, only those devices will be included that have responded

3. If the number of devices still exceeds 10, an error message is issued 4. If less than 3 devices were found in step 1, the limit is reduced to 0,1*In

The diagram can be edited normally, for example by adding or deleting protection devices. When the dialog is closed with "OK", the diagram is saved and can be called up using the list.



Editing selectivity diagrams Existing diagrams can be edited via a diagram list that can be called up using the "Calculation – Current-Time Protection – Diagrams..." menu. Double-click on a diagram in the list to open it. The results of a new calculation - specifically the new current values of the protection devices shown in the diagram - can be applied to the list of currents in this manner, and thus to the diagram. It can be called up with the "new results" button.

Parameters A dialog for the parameters of the protection device file can be called up using the "Calculation – Current-Time Protection – Parameters..." menu. The headlines entered here and the output language will become effective in the documentation (see chapter “Project information” on page 16-4).



The current-time diagrams

General The response of the current-time protection devices are visualized in the current-time diagrams. The response time is shown in dependence upon current. The characteristics must always slope downward, i.e. the response time becomes shorter (or remains the same) as the current rises.

0,100 Ir 1,0 Ir 10 Ir 100 Ir

1000 s

100 s

10 s

1,0 s

0,100 s

0,010 s

Such diagrams are used in a variety of dialog windows, as well as in the documentation of the data. The time axis covers the range from 10 to 1000 s (approx.16 min.). This axis is preset and cannot be modified by the user. The current axis can be marked in relative units (Ir), in A or in kA. The calibration of the current axis and the number of decades to be displayed is determined by the program. It is set to ensure that all information will be visible at all times.

Diagram properties The appearance and properties of the diagrams can be altered. This can be done using the context menu that can be called up with the right mouse button. The context menus vary according to the diagram types, but generally contain the following options:



- Mark supporting points yes/no - Display axis legends yes/no - Open "Diagram Properties" dialog The "Diagram Properties" dialog contains a variety of display options. These settings not only affect the on-screen display of the diagram, but are also effective when the diagram is placed on the clipboard or saved as a metafile. The diagram properties are stored in the Windows registry.

• The display of the axis legends can also be toggled here, as in the context menu.

• The fonts for the axis legends can be selected using a standard dialog. The same font is used for all diagrams!

• The display of the dashed lines for each decade can be toggled. This option is also available in the context menu.

• Enabling "Grid detailed" results in a complete divisioning of the decades by tens.



• The marking of the characteristic supporting points can also be toggled quickly using the context menu, as this may permit easier verification of the characteristic.

• The size of the point markings also corresponds to the mouse-click snap setting and thus affects the editing process.

• The line thickness of the curves and the color settings only become effective when editing the characteristics.

Saving the diagram or copying to the clipboard All diagrams can be saved to a Windows meta file via the context menu (see above). A "Save File" dialog is displayed which contains a file name generated from the current date and time. The "Clipboard" option also uses the meta file format, ensuring that the graphics thus transferred remain easily scalable.



The characteristic editor

The dialog window The graphical editing of the point-by-point characteristics is performed in the following dialog window. The window can be enlarged, but cannot be displayed any smaller.

Activating the "Insert, Move, Delete Points" option (1) enables the direct graphical editing of the characteristic with the mouse. A variety of cursor shapes are used. The mouse coordinates are displayed dynamically in both editing fields (2). When a point of a characteristic has been marked (3), the coordinates of that point are statically displayed and can be edited. Precise numerical values can thus be entered. New characteristic points can also be entered using the input fields. The processing of the characteristic has been substantially improved over the old program version. "Reversed" characteristics no longer occur. A complex algorithm corrects the points as required to ensure a continuously declining characteristic. Functions to simplify the creation and editing of characteristics:



• Any characteristics from the current file can be selected as a "template" (4). The old characteristic is used as a template by default when editing existing characteristics, thus ensuring that changes are immediately visible.

• Standard characteristics (5) can serve as the basis of a new curve. • Moving complete characteristics using factors permits the simple generation

of suitable tolerance curves (6) The buttons for global function are now marked with icons instead of text:

• "Undo" (7) and "Redo" (8) • "Copy" (9) and "Load" (10)

All processing steps can be undone; the redo function, i.e. to undo an undo operation, does not work yet. Diagram properties The appearance and properties of the diagrams can be altered. Ensure that no points are selected when calling up the context menu with the right mouse button (see “Diagram properties” on page 16-10). The diagram properties are stored in the Windows registry. Editing of fuse characteristics The following special features must be observed when editing fuse characteristics:

• The "Template" and "Standard Characteristic" buttons are not enabled. • The current axis and value display indicates ampere values. The current axis

is automatically adapted to the required current range.

Graphical input and editing of characteristics The "Insert" function in the menu or on the tool bar can be used to create a new characteristic. Alternatively, the "New Type" element in the list can be used. Characteristic points may be entered either graphically or numerically. The action can be selected by activating one of the checkboxes:

• Insert..points Point and click with the mouse in the diagram; the displayed coordinates simplify the input. The points are sorted into the characteristic using the current value as the sorting criterion. Time values are corrected as required to prevent reversals of the characteristics.

• Move..points Click on a point to select it and drag the point. The point is "lost" when leaving the valid range. In difficult cases, use numerical inputs for corrections.



• Delete..points Click on a point with the mouse.

The checkbox of the function will remain activated until it is unchecked or an input is made in an input field. Alternatively, the point can be selected with a mouse click; the right mouse button will then bring up the following context menu:

Numerical input of characteristic points The numerical input of characteristic points in the current and time value input fields permits precise values to be entered.

• Entering new points Enter the current and time values in the input fields above the diagram, click "Apply". Note: Ensure that no point is currently selected, otherwise it will be moved.

• Moving a point First select a point. The input fields will now display the exact values. The values can now be changed and applied. The points are also sorted into the characteristic when the input is made numerically, with the current value serving as the sorting criterion. The time values may be corrected as required to avoid reversals of the characteristics.

Specifying standard characteristics The specification of standard characteristics can be a good basis for the input of a specific characteristic. The following characteristics are available:



Creating tolerance characteristics Use the "Move" button to open the following dialog.

An existing characteristic can be easily moved to create a suitable tolerance characteristic.



The module editor

Editing of protection modules A "protection module", also known as a "protective function" or "protective stage", is the smallest functional unit of a protection device. Protection modules have their own library type. The essential properties of the module are defined in one main and several additional data masks. A reduced data mask can be used to change the settings of the module at a later time (see “Setup of protection modules” on page 16-23).

(1) Type name and description (2) Load the module data from the library (3) Copy and load the module data (4) Selection field for the protective function; available options are:

- Overload - Overcurrent - Directional overcurrent - Earth fault - Directional earth fault

(5) Selection field for the characteristic



(6) Definition of the possible options for (5), see “Characteristics” on page 16-18.

(7) Selection field for the reference value of the current setting; available options are: - Rated current Ir - Basic current Ib - Total current I0 - Basic current Ib0 - Setting I1 of 1st protection stage

(8) The type name will be displayed here if the module contains current-time characteristics that have been defined point-by-point, i.e. if "i/t characteristic" has been defined as a possible option under (6); The "..." button calls up the dialog for the selection/input of characteristics (see “Characteristics and tolerances” on page 16-21).

(9) Definition of the current and time setting ranges; see “Coding of the setting ranges” on page 16-22.

(10) Input of positive and negative tolerances; see “Tolerances” on page 16-22. (11) Input of the "basic time" tb of the characteristic or the factor for the sloping

of corners in the case of definite-time overcurrent-time modules.The rate of rise of a current-dependent characteristic, i.e. the response time of the relay, can be set with the time setting "t /p.u.". A value of t = 1.0 p.u. (if tb=1s) results in the original characteristic. A number of manufacturers specify the response time at a multiple of the current setting (generally a factor of 6 or 10) for the time setting. In this case the time reference value can be entered as "tb /s"; the original settings should then be entered under "t /p.u.".

Characteristics The selection field for the characteristic of the protection module (5) contains only those characteristics that have been defined as selectable. The "..." button (6) opens the following dialog for this purpose:



As a rule, 3 groups of characteristics must be distinguished:

1. I-t characteristics in which the curve which has been defined point-by-point is modified by setting values.

2. Definite-time overcurrent-time protection, in which the current and time settings are implemented directly as a right-angle characteristic.

3. Current-dependent characteristics (inverse time) defined by rules and internally calculated on the basis of formulas; the multiplication of these standard characteristics with the time and current settings result in the effective characteristics.

I-t characteristics The "i-t characteristic" option for the characteristic is further subdivided in the options (1), (2) and (3). The different processing of the characteristics is shown in the following graphics. i-t characteristic (1): The processing corresponds to the previous handling of i-t characteristics, i.e. both the i and t values are multiplied by the settings.



0,100 Ir 1,0 Ir 10 Ir 100 Ir

1000 s

100 s

10 s

1,0 s

0,100 s

0,010 s 0,100 Ir 1,0 Ir 10 Ir 100 Ir

1000 s

100 s

10 s

1,0 s

0,100 s

0,010 s

Settings i = 2* Ir, t = 1 p.u. Settings i = 1* Ir, t = 2 p.u.

i-t characteristic (2): The sloping part of the characteristic corresponds to a constant i²t value dependent on the time setting; the current setting only affects the left-hand section of the characteristic.

0,100 Ir 1,0 Ir 10 Ir 100 Ir

1000 s

100 s

10 s

1,0 s

0,100 s

0,010 s 0,100 Ir 1,0 Ir 10 Ir 100 Ir

1000 s

100 s

10 s

1,0 s

0,100 s

0,010 s


i-t characteristic (3):



The sloping part of the characteristic also corresponds to a constant i²t value in this case; however, it is dependent on the current setting; the time setting only affects the bottom section of the characteristic.

0,100 Ir 1,0 Ir 10 Ir 100 Ir

1000 s

100 s

10 s

1,0 s

0,100 s

0,010 s 0,100 Ir 1,0 Ir 10 Ir 100 Ir

1000 s

100 s

10 s

1,0 s

0,100 s

0,010 s


Characteristics and tolerances If "i/t characteristic" is a possible option, the Characteristics bay in the dialog is enabled. At least one characteristic must be defined. The following small dialog field is designed for this purpose, which can then lead onto the editing window for characteristics (see “The dialog window” on page 16-13):

Two characteristics can be specified to depict the tolerance band of the protective function. If only one characteristic is stated, the information pertaining to the



tolerance band becomes effective and the program calculates the minimum and maximum characteristics on he basis of the basic characteristic.

Coding of the setting ranges The coding of the setting ranges is relatively complex when entering protection module data. The most realistic possible depiction of the module's possible settings should be achieved; this will facilitate the subsequent setup of the protection devices significantly, however. The following convention should be observed (the following examples apply for the "comma decimal separator" regional settings) : only one setting value, i.e. cannot be set effectively "1" or "1,0" several different setting values "1;2;3" or

"0,150;0,3;0,45" Setting range in step width, e.g. variable from "2" in steps from "2" to "10"

"2-2-10"

any combination of the codes above separated by semicolons (e.g. 1,2,3,4,6,8,12 can be set)

"1-1-3;4-2-8;12" or "1-1-4;6;8;12" or...

The following coding is generated using the settings when loading old data that only contains the upper and lower limits of the setting ranges. Subsequent editing is generally required. No minimum value (min): min = setting (act) No maximum value (max): max = act min = max = act (=1) "1" min < max: the range is divided into 5 sections, i.e. 6 valid settings are available

"1-1-6"

Setting value between minimum and maximum value: the overall range is divided into two sections, "min..act" and "act..max" e.g. min=1 act=8 max=10

"1-1-6;8-0,4-10

Very large setting ranges with small steps (e.g. "0,010s to 300s in 0,010s increments"), such as those that occur with new electronic relays can lead to storage problems. It would be necessary to save 30000 setting values in the example. To prevent this, the program does not accept any increments smaller than 1%.

Tolerances Protection devices, and thus also protection modules, always have 2 characteristics in the new program version, a minimum ("warm") and maximum



("cold") characteristic. As a result, characteristics are always displayed as an area in the selectivity diagrams. In the case of fuses, 2 characteristics are definitely stated. For protection modules, i.e. relays and tripping devices, tolerances are input directly. The positive and negative tolerances are stated in good technical documentation.

Setup of protection modules A special dialog which has been reduced to essential information is available for the setup of a protection module within the predefined limits. The effective characteristic is displayed during the setup procedure. The following items can be set up:

• "locked" yes/no The module is disabled; unlike the earlier version, information pertaining to the actual function (overcurrent...) is no longer lost.



• Characteristic Especially in the case of inverse time relays, the characteristic can be switched simply between the possible options.

• Current and time settings Only those settings that were previously coded in the setting range are possible. The setting can either be changed using the "+" and "-" buttons or by directly entering the setting in the editing field.



The device editor

General Unlike the previous versions of the program, the protection devices are now organized in various types:

• Fuses • Circuit-breakers (similar to fuses) • Overcurrent releases for low-voltage power circuit breakers • Overcurrent-time relays, secondary relays with transformer connections • Protection object for the illustration of threshold values, motor starting

currents, etc. Protection device types can be stored in device libraries (*.sd3) independently of the device type. In addition, "type series" libraries will be available later with the function "Find suitable fuse for indicated rated current, etc."

Adding new protection devices, wizards Adding new protection devices via the interactive graphic (see “Editing of protection device data” on page 16-5) can be realized in two ways:

• The user enters a protection device typ contained in the allocated library into the first data mask. The program loads the device data from the library and displays the normal dialog.

• The user does not enter a protection device type. The program will launch a wizard to guide the user through the required dialogs in several steps.

The addition of a protection device with the independent program requires the protection device type to be established first. This can be done via the menu ("Edit – Add New Device – Fuse...") or a small dialog box:



The program will then launch a wizard to guide the user through the required dialogs in several steps.

Editing of protection devices The input and editing of data is performed on several tabbed dialog fields. The following tabs are available:

• Info / View (not for library data) - Display / input of topological information - Definition of color and pattern of characteristic

• Text (not for library data) Input of text information, comments for the documentation

• Technical Data (depends on the protection device type) Input of rated and reference current, etc.. In the case of library elements, the type name is also entered here.

• Characteristic(s) (depends on the protection device type) display of the effective characteristics; make adjustments as required

• Let-trough Energy (depends on the protection device type) Information on the let-trough energy of the protection device – not implemented yet!

Not only the data required for the selectivity studies has been recorded, but also that required for cable dimensioning.



"Info / View" tab:

The editing fields for node names, etc. are disabled when the protection device has been called up via the interactive graphic. The data is displayed but cannot be modified. The fixed assignment of the color and pattern of characteristics ensures the consistent display of the characteristics in the selectivity diagrams.

"Text" tab: The text information entered here only appears in the documentation, i.e. in the relay setup tables.



"Technical Data - General" tab: This tab is used for all protection device types: (1) Type information; a unique type name is required for library elements. (2) Button to transfer data from the library; only library elements of the same

protection device type are available. (3) Button to copy the complete technical data of the device, including

characteristics. (4) Button to load the data copied with (3).

The following input fields are available on this tab for protection device types in which the self-impedance of the device has been taken into account in the cable dimensioning:

"Technical Data – Fuses and Circuit-Breakers" tab: The additional data for fuses and circuit breakers only amounts to:

• the rated current Ir • the high test current (I2) related to the rated current

"Technical Data – Tripping Devices and Relays" tab:



The additional data for releases and relays relates to the various currents: Release Relay Ir Rated current of the power circuit-

breaker Primary transformer nominal current

Ib Rated current of the release Basic current (reference current) I0 Rated current of the release for

earth fault detection Primary transformer nominal current, summation current transformer (cable-type current transformer)

Ib0 Reference current for earth fault detection

Basic current for earth fault detection

"Technical Data – Protection Object" tab: Protection objects permit limit values or limit curves to be displayed. The program features functions to generate limit curves.

The rated current Ir (1) of the protection object should always be stated. Thermal limit curves of cables The value I²t (2) to be determined on the basis of the permissible short-circuit current density is converted to a limit curve (t=0...5s) by clicking (3).



0,100 Ir 1,0 Ir 10 Ir 100 Ir 1000 Ir

1000 s

100 s

10 s

1,0 s

0,100 s

0,010 s

The curve generally exceeds the current range up to 100Ir. The rated current is not taken into consideration in the curve, as it applies to a time value of >>1000s. The curve can be supplemented as required. Motor starting currents Clicking button (5) creates a simple acceleration curve (4) if Ian/Ir > 2.0 (red curve).

0,100 Ir 1,0 Ir 10 Ir 100 Ir

1000 s

100 s

10 s

1,0 s

0,100 s

0,010 s

Current flow from result file The button (6) can be used to apply any current line from a motor acceleration result file (*.rmh) as a characteristic. Note:



The result file is searched for the element name of the protection object. If the required element name is not found, a selection list of the available results is displayed. Voltage can only be checked in the case of motors. If the acceleration process does not start at the time 0,0 s, the starting condition will be suppressed to ensure that no reversed characteristics result.

"Characteristic(s) - General" tab: This tab contains a graphical representation of the various device characteristics for all protection device types. For information on the diagram, see “The current-time diagrams” on page 16-10. The representation of the characteristics on the tabs always shows the discrete minimum and maximum characteristics. In the selectivity diagram (see “The diagram editor” on page 16-35) on the other hand, the characteristics will appear as a tolerance area; exception: only individual characteristics are shown for protection objects.

"Technical Data – Fuses, Circuit-Breakers and Protection Objects" tab: The tab shows the characteristics in the diagram; the high test direct current I2 to be entered on the "Technical Data" tab will also be shown as required. Characteristics can be loaded from an open library using the "?" buttons. The dialog described in chapter “The dialog window” on page 16-13 should be called up to edit the characteristics; the diagram is then calibrated in ampere values and current values can be processed without conversion.



"Characteristic(s) - Tripping Devices and Relays" tab: The tab shows all of the characteristics active in the diagram, i.e. the characteristics of blocked protective functions do not appear. In addition to the type of module, the list of protective functions (1) also contains the module's function:

I> Overload I>> Overcurrent -> I>> Directional overcurrent I0>> Earth fault -> I0>> Directional earth fault



Button (2) adds new protection modules to the protection device. The program responds as follows to the selection of a module in the list:

• The (partial) characteristic of the module is highlighted in red in the diagram. • The button (3) to delete the module is enabled. • If it is possible to set up the module, the setup buttons (4) are enabled. The

setting changes become visible in the diagram immediately. • The button (5) to edit the module is enabled. This button opens the dialog

described in chapter “Editing of protection modules” on page 16-17. • The button (6) to set up the module is enabled. This button opens the

advanced setup dialog described in chapter “Setup of protection modules” on page 16-23.



"Let Through Energy" tab: Information related to let through energy is not yet currently processed.



The diagram editor

The selectivity diagram dialog window

Editing in the selectivity diagram dialog window is mainly done using context menus. The dialog window itself contains the following elements:

(1) Current-time diagram to display protection device characteristics - the current axis is automatically determined by the program - the axis legend applies for the basic voltage Ub1 - the characteristics of the protection devices are all converted to the basic voltage

(2) List of the displayed protection devices - when selecting a protection device, the characteristic is marked in the diagram - double-clicking a protection device opens it for editing

(3) List of the entered currents - when selecting a current value, the value is marked in the diagram - double-clicking a current value opens it for editing



(4) Input fields for a maximum of 2 basic (reference) voltages - the input of a second basic voltage will result in a second current axis in the printout.

(5) Display of mouse cursor coordinates (6) The "Text Info" button opens a dialog for the input of a picture number and

title (7) The "Current Results" button only appears when calculation results are

available when working with the interactive graphic (see “Creating selectivity diagrams” on page 16-7).

Editing selectivity diagrams

General A suitable short-circuit current calculation simplifies the creation of a selectivity diagram considerably. The application of current values from calculation results can also be realized with ease (see “Creating selectivity diagrams” on page 16-7).

Adding, editing and deleting protection devices A context menu for editing the displayed protection devices can be called up with the right mouse button while the mouse cursor is either over a characteristic in the diagram, or in the protection device list. The options are:

Edit Calls up the device editor (alternatively, double-click), Insert Adds a further protection device to the diagram.

A selection list is displayed. Delete The selected protection device is removed. Overcurrent etc. Selection of one of the characteristics of the selected

protection device.



Adding, editing and deleting current values Current values are displayed as vertical lines in the diagram; selecting a value in the list highlights it with a red line and its text. A context menu for editing the current values can be called up with the right mouse button while the mouse cursor is in the list. The options are:

Edit Calls up the current dialog (alternatively, double-click). Copy Copies the current value. Insert Adds a new, empty current value to the diagram.

The current dialog is displayed. Delete The selected current value is removed. Text Positioning of the descriptive text top/bottom. The current dialog permits the editing of values and enables the "Copy" and "Load" functions (editing of time-dependent currents and loading from result files have not yet been implemented):



Documentation, print output

General The documentation of protection device data, selectivity diagrams, etc. is currently only possible using the separate SelModul application. The standard options "Printer Setup..." and "Page Setup..." are available in the file menu. Margins and a font for the tables can be specified in the "Page Setup" dialog. The font for the diagram axes is linked to the setting for the screen display of the diagrams (see “Diagram properties” on page 16-10).

The print command from the File menu or tool bar generates the documentation for those elements selected in the element list. If nothing has been selected, all elements will be printed. The results can be checked with the page view.



Library data All library elements can be documented. The documentation on one page contains the data in tables and in some cases in diagrams. The documentation of the library elements will only contain the table header with user information and text lines if a project file is open at the same time.

Protection device setting tables and selectivity diagrams The proven design of the project data documentation has not been changed significantly. The list of current values in the selectivity drawings has been dropped. Instead, the text is output directly in the diagram. The position of the text must be determined when editing the diagrams (see “Adding, editing and deleting current values” on page 16-37).

Distance Protection


Distance Protection

Overview

The module distance protection allows the user • to enter distance protection relays with their settings respectively character-

istics, • to get all voltage, current and impedance values (primary or secondary) seen

by a relay due to a short circuit, • to check the relay settings and • the automatic generation of the tripping schedules.

All impedance values shown in the module are calculated with a short circuit calculation according to the superposition method (see chapter "Short Circuit"). The module distinguishes two types of relays

• user-defined or general relay (relay type given by the user) • predefined relay type (relay type predefined by the program)

The characteristic of a general relay can be entered with the mouse in a R/X- or U/I-diagram or with an input mask. In the mask the characteristic is entered with coordinate pairs. The type of the relay can be entered by the user in the distance protection mask. When selecting the relay type from a predefined list, the user will be able to enter the relay dependent setting parameters in a special input mask. The characteristic will be built up by the program. The predefined list will be displayed, when press-ing "relay type ?" in the distance protection mask. The input of relay data is possible after having selected the button "Characteristics" in the distance protection mask. The evaluation respectively the check of the relay settings can be done with option "Calculation - Distance Protection - Evaluation" in the main menu.

Distance Protection


Menu Options for Relays

A distance protection relay (DP-relay) must be first entered graphic- or list-oriented with the option "Input - Switch/Protection - Distance Relay" to determine the relay location. The relay specific data can be entered after having entered the relay type and after having pressed the push button "Characteristics". The relay window will be opened with a menu bar. The data can be entered with the mouse or in masks (dialog boxes). The following menu options are available:

• Relay • Starter • Tripping • Tripping Time • View • Parameter • Tripping schedule.

With the menu option "view" the user can select if the starter or tripping character-istic or the tripping schedules should be displayed. Under the menu option "Relay", the following options are available:

Copy / Paste All relay data except the tripping schedules are copied into a buffer. Selecting "Paste" the data are transferred from the buffer to the relay.

Old State After having pressed the button "Characteristics" in the DP-relay mask all data are saved into a separate buffer. In case of erroneous input the user can get the old data from the buffer with this option. This function corresponds to the "Cancel" function in the element input mask.

Print This option is to print the contents of the relay window. The printer setting is made in the main menu.

Clipboard This option is to save the contents of the relay window on to the clipboard.

Distance Protection


Documentation This option is to make a documentation of the present relay or of the pre selected relays. The relays to be documented can be selected from the list (see "Relay - Documentation - Relay selection").

Exit This option is to exit the relay window. In the relay window the following information are displayed:

• relay name • relay type • relay location • protected element • nominal system voltage Un • statement, whether the impedance are primary or secondary values • ratio Ki/Ku (current transformer ratio to voltage transformer ratio) • complex ratio k0 (amount and angle) of the element’s zero sequence imped-

ance and the positive sequence impedance, k0 = (Ze(0) - Ze(1)) / (3*Ze(1)) This value appears only, when the asymmetrical fault type is set in the global parameters

• statement, whether line-line or line-earth faults are examined. The fault type can be set in the global parameters

During entering data with the mouse the mouse position is displayed (see "Starter Characteristic L-L" on page 10-6).

Remark Before opening the relay window, the program checks, if the tripping schedules for the relay have already been built up (see "Tripping Schedules" on page 10-27). If the schedules exist already, the message "After topology change: build up the tripping schedules!" will appear. Pressing "Yes", the tripping schedules for the selected relay and for all other relays, which are in the schedules of the selected relay will be rebuilt. This is only significant, when in fact the topology or the element data has been changed. Further menu option are explained below.

Distance Protection


Starter

This menu option is available, when the option "View - Starter" is activated. The following starter systems can be entered:

• overcurrent • under impedance • characteristic L-L for line-line faults • characteristic L-E for line-earth faults

The starter system can be selected with the last 4 menu options. The corre-sponding menu option will be checked. Additionally to the above mentioned starter system the user can define an earth fault detection system. Below all input data for the different starters are explained. The values can be entered with the mouse or in masks.

Overcurrent The input data are:

Io L (*Ir): Phase current limit related to the current transformer’s primary current Ir. Value for line-line and line-earth faults. Starting condition: Ik"(L1) >= Io L or Ik"(L2) >= Io L or Ik"(L3) >= Io L.

Io S (*Ir): Total current limit related to the current transformer’s primary current Ir. Value for line-earth faults. Starting condition: (Ik"(L1) + Ik"(L2) + Ik"(L3)) >= Io S.

The entered data are displayed in a U-I diagram.

Under Impedance The data are entered according to fig. 10.1:

Distance Protection


U limit max

Io1I limit

I / Ir

U / Ur

U limit min

Starting area

Fig. 10.1a Phase-independent under impedance starter

U limit min =

Io 1 Io 2I limit

I / Ir

U / Ur

U limit max

Starting area

Fig. 10.1b Phase-dependent under impedance starter The input data are:

I limit (*Ir): Phase current limit related to the current transformer’s primary current Ir. Value for line-line and line-earth faults.

Io 1 (*Ir): 1. overcurrent limit in a phase related to the current transformer’s primary current Ir. Value for line-line and line-earth faults.

Io 2 (*Ir): 2. overcurrent limit in a phase related to the current transformer’s primary current Ir. Value for line-line and line-earth faults.

U limit min (*Ur):

Minimum voltage limit between line-earth or line-line (see below) related to the voltage transformer’s primary voltage Ur.

U limit max Maximum voltage limit between line-earth or line-line (see below)

Distance Protection


(*Ur): related to the voltage transformer’s primary voltage Ur. Phi min, Phi max:

Minimum and maximum phase angle for a phase-dependent starter in degree. In case of a short circuit and if the angle between phase current and phase voltage is between Phi min and Phi max, the current limit Io 2 is considered instead of Io 1.

I sum (*Ir): Total current limit related to the current transformer’s primary current Ir. Value for line-earth faults. Starting condition: (Ik"(L1) + Ik"(L2) + Ik"(L3)) >= I sum.

UL-L, UL-E Dependent on the activated check box, the program takes the line-line or the line-earth voltage to compare with the limit values "U limit min" and "U limit max".

The value "Io 2" should not be entered or set to zero for phase-independent under impedance starters. The input of "Phi min" and "Phi max" is then unimportant. The value "Io 2" must be defined for a phase-dependent under impedance starter. The values "U limit min" and "U limit max" must be set equal.

Starter Characteristic L-L With this option the user can enter

• a polygon or • a circle

as starter characteristic for line-line faults in the R/X-diagram. The values can be entered with the mouse or in a mask. If the measured impedance is inside the polygon or inside the circle the relay will start. Dependent on the relay type (user-defined or predefined relay) and the input mode (mouse or mask) the following menu options are available:

Setting Parameters This menu option is only available when working with predefined relay type. The setting parameters of the predefined relay are shown in section "Tripping" on page 10-10.

Limit Current Additionally to the starter characteristic the user can enter a limit current I limit. If a value is entered, the relay starts only when the following conditions are valid

• Ik"(L1, L2, L3) >= I limit and • impedance Z inside polygon respectively circle.

Distance Protection


The value I limit must be entered related to the current transformer’s primary current Ir.

Entering the settings with the mouse

Input After having selected the option a polygon or a circle (dependent on the activated option in the menu) can be entered. A polygon can be entered with mouse clicks in the R/X-diagram. The input terminates after a double click. The program connects the first and the last entered point to a closed polygon. During the input the mouse position is given:

X / Ohm

R / Ohm

PXp

Rp

Phi

BetaRp =Xp =Phi =Beta =

mouse positition:

Fig. 10.2 Mouse position In addition to the mouse position (R, X, and Phi) the angle Beta is also given. The angle Beta represents the angle between the last entered section and the section, which would be built with the next entered point. In the mask for dimensions the drawing area (minimum and maximum values in vertical and horizontal direction), the grid, etc. can be defined. The mouse position will also be displayed in the Z/T- and X/T-diagram. A circle will be defined with the input of a center (mouse click). With dragged mouse the radius can be entered.

Delete, Undo After having selected this option the characteristic can be deleted. Option Undo undeletes the last deletion.

Distance Protection


Entering the settings with the mask With menu option "Starter - Characteristic - Mask" the mask for entering the starter-characteristics appears. This mask appears also, when selecting the menu option "Tripping - Characteristic - Mask". The following input is possible:

Characteristic for Starter / Tripping Dependent on this input a starter or a tripping characteristic is entered.

Displayed Stage The stage, which characteristic is entered or displayed, must be defined. For starter this input is meaningless.

Fault Type Gives the fault type the input values are for (L-L: line-line, L-E: line-earth faults).

Characteristic Type The user has to define the characteristic type (circle or polygon). Dependent on the activated radio button different input fields are available. A circle is defined by a center and the radius. A polygon is defined by the input of a sequence of x,y-points. The polygon can be changed with the push buttons "Insert" and "Delete". The polygon points are displayed in a list. The first point must be different than the last point. The polygon will be closed by the program itself.

Earth Faults Detection This starter type is only for earth faults. The input values are:

Earth current IE(*Ir) Earth current related to the current transformer’s primary current Ir. Starting condition: (Ik"(L1) + Ik"(L2) + Ik"(L3)) >= IE.

Earth voltage UE(*Ir) Earth voltage (displacement voltage) related to the voltage transformer’s primary voltage Ur. Starting condition: (Uf(L1) + Uf(L2) + Uf(L3)) >= UE. Uf: Fault voltage line-earth.

If there is no earth faults detection, no values may be entered here. The earth faults detection works additionally to other starter systems.

Distance Protection


Starter Characteristic L-E With this option the user can enter


as starter characteristic for line-earth faults in the R/X-diagram. The values can be entered with the mouse or in a mask. If the measured impedance will be inside the polygon or inside the circle the relay will start. The menu options are the same as in section "Starter Characteristic L-L" on page 10-6.

Distance Protection


Tripping

This menu option is available, when the option "View - Tripping" is activated. The tripping can be entered for user defined relay

• with impedance values (settings) or • as a characteristic (polygon or circle) for line-line or line-earth faults and • for predefined relay directly with its setting parameters

The kind of input can be chosen under the menu option "Tripping". Additionally an overcurrent-time function with 2 stages as back-up protection can be defined. The tripping stages can be automatically set by the program. The characteristics can be displayed in the R/X-, Z/T- or X/T-diagram (see "Relay-Specific Parameters" on page 10-26).

Impedance Stages for User Defined Relay The setting values can be entered as primary or secondary values (see "Relay-Specific Parameters" on page 10-26). The transformer ratio and the impedance of the protected line or the impedance to the next relay node are displayed. The input values are:

Stage 1, 2, 3, 4: Threshold impedance or reactance value of 1., 2., 3. and 4. Stage in Ohm per phase. The value can be entered in per cent related to the line impedance or impedance to the next relay node/station. If the relay has only 3 stages, the value for the 4. stage may not be entered.

Transition stage Threshold impedance or reactance value of the transition stage in Ohm. The value can also be entered in per cent related to the line impedance.

Backward stage Threshold impedance or reactance value of the backward stage in Ohm. The value can be entered in per cent related to the line impedance. The backward stage shows always in the opposite direction of the 1. stage.

The values are for line-line and line-earth faults. After quitting the mask the settings are shown in the R/X-, Z/T- or X/T-diagram.

Distance Protection


Tripping Characteristic L-L With this option the user can enter


as tripping characteristic for line-line faults in the R/X-diagram. The values can be entered with the mouse or in a mask. The input can be done for 4 stages, 1 transition stage and 1 backward stage in the same way as for the input of the starter characteristics (see "Tripping Characteristic L-E" on page 10-11). The only difference is the deletion of a stage. After having selected "Delete" the character-istic, which has to be deleted, can be clicked. Undo undeletes the last deleted characteristic. In the Z/T and X/T-diagram no characteristics can be entered.

Tripping Characteristic L-E With this option the user can enter


as tripping characteristic for line-earth faults in the R/X-diagram. The values can be entered with the mouse or in a mask. The input can also be done for 4 stages, 1 transition stage and 1 backward stage (see "Tripping Characteristic L-L" on page 10-11).

Setting Parameters for Predefined Relays The following relay types are predefined

• ABB REL316 • Siemens 7SA511/7SA513 • AEG PD551/PD531 and SD36

The input mask will appear when selecting "Characteristic L-L faults" or "Characteristic L-E faults" in the "Starter" or "Tripping" menu. The parameters for starting and tripping can be entered in the mask. The documentation and the automatic setting of the relay can be done directly in the mask. For automatic setting the fault type should be set to asymmetrical fault in the global parameter mask. In this case the impedances of the zero sequence are also calculated.

Distance Protection


If there is a overcurrent or under impedance with U/I-characteristic starter function the input has to be done according to the section above (see "Starter" on page 10-4). The setting parameters are explained in the corresponding manual.

ABB REL316 Starter characteristic:

RLoad

RA

RB

-RLoad

XA

XB

AngleLoad

X

R

Tripping characteristic (only for 1st stage)

X

-X / 8

X

R

-RR / 2

-RRE / 2

RRE

RR

27°

27°

7°

For each stage the k0-factor has to be entered (amount and angle):

k0 = (Zst(0) - Zst(1)) / (3*Zst(1))

Distance Protection


Siemens 7SA511, 7SA513 Starter characteristic:

RA1 RAE

RA2RAE

X+A

X-A

RA2

X

RRA1

PHIA

Tripping characteristic (only for 1st stage)

X1

R1RE1

RE1

X

RR1

45°

Distance Protection


AEG PD531, PD551, SD36 Starter characteristic (only for PD551):

Beta

110°

Rv L-L

Xv

Zr

X

R

Zv

70°

Rv L-E

Tripping characteristic polygon (only for 1st stage)

-X

-135°

X

Alpha

-RL-L

X

R

RL-L

RL-E

-RL-E

Tripping characteristic circle with or without arc compensation (only for 1st stage)

Distance Protection


-135°

Delta

Alpha

X

R

Arc compensation

Phi

The function to get the arc compensation circle is:

Delta is in the range -45° < phi < alpha: delta = alpha - phi and in the range 135° < phi < (alpha + 180°): delta = alpha - phi + 180° For the overreach stage the factor ku for L-L and L-E faults must be entered.

Back-up Protection The distance protection relay can also be defined as an overcurrent relay. The input values are:

1. stage I (*Ir) Current setting value of 1. stage related to the current transformer’s primary current Ir.

1. stage t Tripping time of 1. stage in seconds. 2. stage I (*Ir) Current setting value of 2. stage related to the current

transformer’s primary current Ir. 2. stage t Tripping time of 2. stage in seconds. Earth current Ie (*Ir) Current setting value for line-earth faults related to the

current transformer’s primary current Ir. Tripping condition (Ik"(L1) + Ik"(L2) + Ik"(L3)) >= Ie.

t (earth current) Tripping time for line-earth faults in seconds.

Distance Protection


When evaluating the relay settings and if the relay has not been started by the distance protection relay, the values of the back-up protection are checked (see Relay evaluation). If there is no overcurrent functionality in the relay no values have to be entered here.

Automatic Impedance Setting The threshold impedance values or the characteristics of the stages 1 to 4 are automatically calculated by the program with the help of the automatic generated tripping schedules. The program generates all possible schedules, that the relay would see in forward and backward direction independent of the network type (unmeshed or meshed). The generated schedules can be changed by the user. Deleting and inserting nodes, he can build up his own schedules (see menu option "Tripping schedule - Edit"). Starting from the correct tripping schedules (network impedances) the program will automatically set the threshold impedance values or the characteristics. The user has to decide by itself, which tripping schedules have to be taken. Not important schedules must changed or deleted! The arbitrary number of schedules are reduced to a single schedule with the smallest impedances. For the setting, only the relay nodes are considered.

Z / Ohm

1. 2. 3.

Relay location A

Stage

Generated schedules

Resulting scheduleR

R

R

R

B C D

Fig. 10.3 Getting the minimum impedance path in meshed networks With the minimum impedance path the relay in location R will be set. The setting of the stages are made according to the following rules:

Distance Protection


1. stage: RRI = p1 ⋅ RAB 2. stage: RRII = p2 ⋅ (RAB + p1 ⋅ RBC) 3. stage: RRIII = p3 ⋅ (RAB + p2 ⋅ (RBC + p1 ⋅ RCD)

1. stage: XRI = p1 ⋅ XAB 2. stage: XRII = p2 ⋅ (XAB + p1 ⋅ XBC) 3. stage: XRIII = p3 ⋅ (XAB + p2 ⋅ (XBC + p1 ⋅ XCD)

with: RAB, XAB Impedance between station A and B RBC, XBC Impedance between station B and C RCD, XCD Impedance between station C and D RR, XR Stages 1 to 3 of the relay R p1, p2, p3 Parameter for setting the stages (p = 0.85 .. 0.9).

The parameters p can be entered in the global calculation parameters. If only 3 stages should be automatically set, the parameter p4 for the 4. stage should not be entered. The same is valid for the overreach stage. The backward stage will not be set. The minimal impedance path can be displayed in the R/X-diagram with menu option "View-Minimum impedance path". In the documentation of a relay these impedance values are also shown (see "Relay Documentation" on page 10-30). Dependent on the activated menu option in "Tripping" the calculated setting values are the threshold impedance values or the characteristics. The character-istics can be polygons or circles. The type of characteristic can be entered in "Tripping - Characteristic". The points of the polygon (rectangle with 1 point in the origin 0;0) are calculated with the help of the line impedance. With ZR as calcu-lated impedance, the polygon points in the R/X-diagram are calculated as follows:

P1 = 0.0, 0.0 (R, X) P2 = 0.0, XR P3 = RR, XR P4 = RR, 0.0

The calculated impedance values are corrected with the arc resistance and the resistance for tower footing path. These values can be entered in the relay specific parameters.

Distance Protection


Correction for line-line faults: RR = RR + RfL-L / 2 Correction for line-earth faults: RR = RR + RfL-E + RM with: RfL-L Arc resistance for line - line faults

(see "Relay-Specific Parameters" on page 10-26) RfL-E Arc resistance for line - earth faults

(see "Relay-Specific Parameters" on page 10-26) RM Tower resistance for tower footing earth path

(see "Relay-Specific Parameters" on page 10-26) The calculated setting values are rounded to the snap entered in the mask for dimensions.

Distance Protection


Tripping Time

The user can enter the tripping time of each stage.

Input The input values are:

Stage 1, 2, 3, 4: Tripping time of 1., 2., 3., 4. stage in seconds for line-line faults and line-earth faults.

Measuring direction: Measuring direction of the stages 1 to 4 and of the end times. The check boxes are for: pos: positive measuring direction neg: negative measuring direction block: corresponding stage is blocked If a stage is bi-directional then both checkboxes ("pos" and "neg") must be activated.

Backward stage: Tripping time of backward stage in seconds. Directional end time: Directional end time of relay in seconds. Bi-directional end time: Bi-directional end time of relay in seconds. Is only

valid, if no value for directional end time is entered.

Automatic Time Setting After having selected this option the tripping times are calculated by the program. The tripping values are taken from the default values given in the global calcula-tion parameters. If a node in the tripping schedule is a distribution pole with at least one out leading branch, which is protected by an overcurrent-time relay or fuse, then the tripping time will be corrected. The tripping time of the overcurrent-time relay (fuse) in the out leading branch can be entered in the node mask, input field "t dp" (see "Node Data" in chapter "Element Data Input and Models"). The fastest tripping time of the distance protection relay is set in order to have a tolerance time between the tripping time of the overcurrent relay (fuse) and the fastest tripping time of the distance protection relay. Nodes without distance protection relay are also considered. The tolerance time can be entered in the global calculation parameters.

Distance Protection


View

With this option the user can decide, if • the starter characteristic • the tripping characteristics • the tripping schedules in forward and/or backward direction or • the network impedances (impedance path)

have to be displayed in the relay window. Additionally the dimensions can also be entered.

Starter The overcurrent starting values, the under impedance starting values or the char-acteristic is shown in the U/I-diagram respectively R/X-diagram.

Tripping The tripping characteristics are displayed in the R/X-, Z/T- or X/T-diagram, dependent on the input in the relay-specific parameters. The input of characteris-tics can only be done in the R/X-diagram. The calculation of the impedance values from the R/X- to Z/T- or X/T-diagram is done with the help of the complex line impedance. The crossing points of the line impedance and the characteristics (polygon or circle) are taken in the Z/T- or X/T-diagram. The distance of these crossing points to the origin (0,0), represents the impedance, which is shown in the Z/T-diagram:

Distance Protection


1. Stage

X/Ohm

R/Ohm

Line

1. Stage

t/s

Z/Ohm

P1

P2 P3

P4Phi L

Fig. 10.4 Calculation of the impedance values from the R/X- to the Z/T-diagram If working with the X/T-diagram, only the reactance will be taken instead of the impedance.

Tripping Schedule After having selected this option a list of tripping schedules is displayed. These are automatically generated by the program. It is advisable to build up the tripping schedules with "Tripping Schedules - Build-up" and to look at these with "Tripping Schedules - Edit". The distance of the nodes from the relay location, which should be considered in the schedules, can be entered in the global parameters, input fields "Fault distance positive direction" and "Fault distance negative direction". A tripping schedule can be selected when double clicking a schedule or pressing "Select" in the list. Clicking the push button "D.backward" the tripping schedules in backward direction (negative impedances) are displayed. It is possible to display one schedule in forward direction and one in negative direction. The schedules must be selected one by one with this option. Pressing "Close" no schedule will be displayed in the corresponding direction. The time step characteristics are always displayed in the Z/T- or X/T-diagram. Additionally to the time step characteristics of the relays in the tripping schedule, the node impedances are displayed (vertical lines). The characteristics of the current relay are in the same color as the node impedances, which are seen by the relay. The vertical lines are dashed. The characteristics of the other relays are drawn in other colors. If a relay see an already drawn node with a different imped-

Distance Protection


ance, the node (vertical line) will be drawn again with the same color as the relay characteristics. This can happen in meshed networks or when there are one or several feeders in that part of the network, which is represented by the schedule.

Network Impedances (Impedance Path) This option is to display in the R/X-, Z/T- or X/T-diagram all impedances (dependent on the fault distance!), which are seen by the relay, in case of a short circuit in the nodes of the tripping schedules. The voltages and currents seen from the relay are also displayed in the U/I-diagram. The user can select the following options:

• Selection impedance path. The user can select an arbitrary impedance path (tripping schedule)

• Display impedance path. If checked, the impedance path is displayed. • All impedances. All impedance paths are displayed. • Only relay nodes. If checked, only the impedances of the relay nodes are

displayed • Minimal impedance path. If check the minimal impedance path is shown (see

"Automatic Impedance Setting" on page 10-16)

It is also possible to select only one schedule in positive and/or one in negative direction. In this case only the nodes of the selected schedule are displayed.

Dimensions For the representation of the starter and tripping characteristics the following values can be entered:

Xmin: Minimum value for the x-axis resp. horizontal direction. It could be for a current value I/Ir or an impedance or reactance value in Ohm.

Xmax: Maximum value for the x-axis resp. horizontal direction. It could be for a current value I/Ir or an impedance or reactance value in Ohm.

Ymin: Minimum value for y-axis resp. vertical direction. It could be for a voltage value U/Ur, an impedance or reactance value in Ohm or a time value in seconds.

Ymax: Maximum value for y-axis resp. vertical direction. It could be for a voltage value U/Ur, an impedance or reactance value in Ohm or a time value in seconds.

Scaling: Scaling of x- and y-axis. Grid: Mouse grid for the input of characteristics in the R/X-diagram.

Distance Protection


The quantities to be displayed in the x- and y-axis could be entered in the mask for relay-specific parameters. For the representation of the tripping schedules the following values can be entered:

Zmin: Minimum impedance value in Ohm for x-axis resp. horizontal direction.

Zmax: Maximum impedance value in Ohm for x-axis resp. horizontal direction.

Tmax: Maximum time value in seconds for y-axis resp. vertical direction.

Z scaling: Scaling of x- respectively z-axis. t scaling: Scaling of y- respectively t-axis. Number of char.: The number of characters for relay, node and element

description can be entered. This input is important, when the schedule is dense.

Number of pages: The tripping schedule can be displayed and plotted on different pages. The number of pages can be entered here. Scrolling forward and backward can be done with the menu options "Tripping schedule scroll".

Distance Protection


Parameter (DP)

With this menu option the global and the relay-specific parameters can be defined.

Global Parameter (DP) The mask for global parameters can also be called with "Calculation - Distance Protection - Parameter" in the main menu. The calculation parameters are:

Project descr: The project description is only displayed. It can not be changed. See menu option "Project-Info" in chapter "Menu Options".

Variant: Description of the variant. Kind of fault: Type of fault at faulted nodes. Possible faults are:

* 3-phase SC: 3-phase short circuit. * 1-phase GND: 1-phase to ground short circuit. * 2-phase SC: 2-phase short circuit. * 2-phase GND: 2-phase to ground short circuit. This input influence the calculation of the impedances, the relay documentation as well as the relay settings (line-line or line-earth).

Calc.method: Following calculation methods are possible: * Superpos. w.out LF: The fault current Ik", the impedances and the voltages are calculated according to superposition method without prefault voltages from the Load flow. The EMF are 1.1*Un. * Superpos. with LF: The fault current Ik", the impedances and the voltages are calculated according to superposition method with prefault voltages from the Load flow. A Load flow calculation must have been performed, before setting the DP-relays (Short circuit calculation).

F. distance forw.: The fault distance is the distance of the nodes, which are considered when generating the tripping schedules, from the relay location in forward direction. The input is also valid for the evaluation of the relay settings.

F. distance backw.: The fault distance is the distance of the nodes, which are considered when generating the tripping schedules, from the relay location in backward direction. The input is also valid for the evaluation of the relay settings.

Distance Protection


Tolerance time: Tolerance time in seconds is the time between the tripping time of a overcurrent-time relay or fuse (in an out leading branch) and the fastest tripping time of the DP-relay. This input is only for the automatic settings of the tripping times (see "Automatic Time Setting" on page 10-19).

ZfL-L(R,X): Fault impedance (resistance and reactance) in Ohm for line-line faults. These values are only for the evaluation, not for automatic impedance setting.

ZfL-E(R,X): Fault impedance (resistance and reactance) in Ohm for line-earth faults. These values are only for the evaluation, not for automatic impedance setting.

Text file: Name of result text file (*.TXT-file). This file will be needed to list the results of the evaluation (see "Checking the Relay Settings" on page 10-33).

Result file: Name of ASCII-file (*.RDS-file). This file can be read by external programs such as Excel for evaluation purposes. The generation of this file can be prevented. The description of the fields can be activated with checkbox "Description". They are the same as in section "Checking the relay settings".

Description: The fields in the result file are described. Phases: Gives the phases (L1 or L123 or 120) of the results to be

listed in the text file. For symmetrical faults only the results of phase L1 will be given.

Time / Impedance values:

For the automatic relay setting the default values can be entered here. Section Automatic impedance setting shows, how the relay stages are set in dependence on the here entered parameters (percentage values). If a stage should not be set automatically, the corresponding values must not be entered. It is not allowed to leave out one stage, that means e.g. to enter the values for stage 1 and 3 without entering the values for stage 2.

Tripping schedules:

The impedance values in the tripping schedules can be primary or secondary values. The input can be done here.

Header: The header in the listing can be activated or deactivated.

Distance Protection


Relay-Specific Parameters The parameters are:

Relay type: Type of relay. The same input can be done in the mask of section "Distance Relay Data" in chapter "Element Data Input and Models".

Description: Relay description. RfL-L Arc resistance in Ohm for line-line faults in order to make an

automatic setting of the impedance stages (see "Automatic Impedance Setting" on page 10-16).

RfL-E Arc resistance in Ohm for line-earth faults in order to make an automatic setting of the impedance stages (see Automatic impedance setting).

Rm Tower resistance in Ohm for tower footing earth path in order to make an automatic setting of the impedance stages (see "Automatic Impedance Setting" on page 10-16).

Impedance values:

The impedance values can be entered or displayed as primary or secondary values. The network impedances are also displayed according to this input.

Tripping characteristic:

Dependent on this input, the relay settings and the network impedances are displayed in the following diagrams: R/X: x-axis: resistance R in Ohm y-axis: reactance X in Ohm Z/T: x-axis: impedance Z in Ohm y-axis: tripping time in seconds X/T: x-axis: reactance X in Ohm y-axis: tripping time in seconds The input for Z/T and X/T is also valid for the representation of the tripping schedules.

Distance Protection


Tripping Schedules

Build-up This function generates automatically the tripping schedules for the selecting relay in dependence on the fault distance in positive and negative direction. The fault distances are entered in the mask for global parameters. The tripping schedules of all relays, which are in the schedule of the selected relay, are also built. When opening the relay window (clicking "Characteristics" in the DP-relay mask), the program asks, whether the tripping schedules should be rebuilt or not, if the schedules have been built already. The schedules must be rebuilt, when the network data or the topology has been changed.

Edit The tripping schedules of the selected relay can be edit. After having selected this option the generated schedules are listed. All nodes are listed, which are connected with the ending node of the protected line. The relay location is not displayed, because it will always be the first node in the schedules. The available options are:

D.backward, D.forward Pressing this option the schedules in forward or backward direction are displayed.

Edit With this option the selected tripping schedule can be edit. All nodes of this schedule (incl. relay location and ending node of the protected line) are listed. With the functions Delete the marked node can be deleted from the schedule. The first two nodes can not be deleted. With function Append a new node can be appended in the schedule. The program lists all possible nodes, which can be appended. These are nodes, which are connected through an element with the last node in the schedule. The element is also displayed. In general only the nodes, which are in the predefined fault distance in positive and negative direction from the relay location are listed respectively can be appended. A node (in the predefined distance from the relay) will no more be listed, if this node has been deleted from all schedules. Therefore it is advisable to build-up first the desired schedule and afterwards to delete nodes or whole schedules.

Distance Protection


Append This option appends a new schedule. With "Edit" the desired schedule can be built-up (see above).

Delete A tripping schedule can be deleted with this option.

Scrolling forward/backward This option scrolls the pages of the tripping schedule, if the schedule is displayed in different pages (see number of pages in section "Dimensions" on page 10-22).

Distance Protection


Procedure for Entering a Relay

For the input and setting of a relay the following procedure has to be done:

• Step: Insert all distance protection relay in the network. This can be done graphic- or list-oriented. Each relay has an identifier.

• Step: Insert to each DP-relay current (CTs) and voltage transformers (VTs). The VTs are also assigned to an element and not to a node. If several elements leads to a node, it is sufficient, to insert one VT to one of these elements.

• Step: Select a relay (mask and afterwards relay window) and look at the parameters. In the global parameters the input values "fault type" and "fault distances" are important. In the relay-specific parameters the user can choose, whether he likes to work with primary or secondary impedance values.

• Step: Let the program generate the tripping schedules. Check the tripping schedules and if necessary change or delete them. It is important that the relay location will not appear twice in a schedule. This can happen in meshed networks. With the delete function the relay location and/or undesired nodes can be eliminated.

• Step: With correct tripping schedules, the starter and tripping characteristics can be entered. Especially for the automatic relay setting, a correct tripping schedule is important.

When generating the tripping schedule, all nodes, which are reducable, are not considered (see "Node Data" in chapter "Element Data Input and Models").

Remark: A DP-relay, which is located in a node (sleeve) between a disconnect/load switch and a line, will be relocated to the correct bus bar by the program, if the sleeve respectively the switch will be reduced.

H1A B

DP

DP

Distance Protection


Relay Documentation

With the menu option "Relay - Documentation - Present relay" the documentation of the present relay can be done. To get zero sequence impedances set the fault type to asymmetrical fault in the global parameters. The documentation consists of three pages.

Relay settings

**************

Relay name : DSR-41

Description :

Relay type : ABB-REL316

Relay location : ONODE 1

Branch : L-002

Line length /km : 5.0

Network impedances(primary):

----------------------------

1.stage 2.stage 3.stage 4.stage

X(1)tot /Ohm : 1.088 2.169 (see below)

R(1)tot /Ohm : 3.202 7.383

Z(1)tot /Ohm : 3.382 7.695

Phi(1) /G : 18.763 16.370

----------------- Zero impedances ------------

X(0)tot /Ohm : 5.748 20.702

R(0)tot /Ohm : 7.064 24.143

Z(0)tot /Ohm : 9.107 31.804

Phi(0) /G : 39.137 40.612

----------------- Earth factors -------------

k0 : 0.597 1.082 (see below)

phi(k0) : 31.590 31.506

RE/RL : 0.402 0.757 (see below)

XE/XL : 1.428 2.849

Parameters: (Input values)

-----------

Voltage transfor.: Ur1 /V: 20000

Ur2 /V: 100

Current transfor.: Ir1 /A: 20000

Ir2 /A: 100

Ratio : Ki/Ku : 0.25

Arc resistance Ph-Ph RfLL /Ohm :

Arc resistance Ph-E RfLE /Ohm :

Tower earthing resistance RM /Ohm :

Distributed reactance X'(sec)/Ohm/km : 0.272

(distributed line reactance)

Distance Protection


Z / Ohm1. 2. 3.

Relay location

Stage

Impedancestage 1

Impedancestage 2

Impedancestage 3

The impedance values of stage 1 represent the line impedance or the impedance to the next relay node. The impedance values are given for the positive and zero system. To get the values of the zero the fault type in the global parameters must be set to an asymmetrical fault. In order to get the line impedance between stage 1 and 2 a subtraction of the impedance values of stage 2 and 1 must be done. The following values for each stage are also given:

k0 = (Z(0) - Z(1)) / (3*Z(1)) RE/RL = 1/3*(R(0)/R(1) - 1) XE/XL = 1/3*(X(0)/X(1) - 1)

The second page shows the set values for a general relay, that means independ-ent of its type.

Set values (relay independent):

-------------------------------

primary secondary Time(L-L, L-E)

1.stage

X1 /Ohm : 0.925 0.231 0.100 0.100

R1 /Ohm : 2.722 0.680

R1+RfLL/2 /Ohm : 2.722 0.680

R1+RfLE+RM /Ohm : 2.722 0.680

X0 /Ohm : 4.886 1.222

R0 /Ohm : 6.004 1.501

2.stage

X1 /Ohm : 2.098 0.525 0.600 0.600

R1 /Ohm : 6.195 1.549

R1+RfLL/2 /Ohm : 6.195 1.549

R1+RfLE+RM /Ohm : 6.195 1.549

X0 /Ohm : 4.886 1.222

R0 /Ohm : 6.004 1.501

Overreach stage

X1 /Ohm : 1.305 0.326

R1 /Ohm : 3.842 0.961

R1+RfLL/2 /Ohm : 3.842 0.961

R1+RfLE+RM /Ohm : 3.842 0.961

Distance Protection


X0 /Ohm : 6.898 1.724

R0 /Ohm : 8.477 2.119

Direct. final stage /s : 4

Non-dir. final stage /s :

Starter (type of starter)

-------

Overcurrent starter : IL(*Ir1) : 2

IS(*Ir1) :

The third page will only be displayed when working with the predefined relay types. The values for the setting parameters are shown, e.g. ABB REL316.

Set values (primary):

---------------------

1.stage 2.stage 3.stage Ov.stage Bw.stage

X /Ohm : 0.925 2.098 1.305

R /Ohm : 2.722 6.195 3.842

RR /Ohm : 2.722 6.195 3.842

RRE /Ohm : 2.722 6.195 3.842

k0 : 0.597 1.017

k0Ang : 31.590 33.065

Time /s : 0.100 0.600

Starter

-------

XA /Ohm : 9

XB /Ohm : -8

RA /Ohm : 8

RB /Ohm : -6

Rload /Ohm : 5

AngleLoad /G : 45.0

Remarks:

--------

............................................................

............................................................

............................................................

............................................................

Distance Protection


Checking the Relay Settings

After having set all relays, the settings can be checked. Several variants (different fault locations, faults on lines, arbitrary fault types) can be calculated now and the program calculates the tripping times of the relays. The evaluation can be done according to:

• fault location • relay location.

The above described options can be selected from "Calculation - Distance Protection" in the main menu.

Fault Locations The input of fault locations is described in chapter "Short Circuit".

Line Faults See chapter "Short Circuit".

Evaluation According to Fault Locations After having selected this option short circuits are calculated in all faulted nodes. All relay in the predefined fault distances from the faulted node are checked. The results are listed in a text file, which name has to be entered in the mask for global parameters. The list is node-oriented and is shown below:

Distance Protection


+-----------------------------------------------------------------------+

| |

| Fault location: AU_BB12 |

| |

|-----------------------------------------------------------------------|

|DP-Relay (prim.)|Di| I/kA | AI/D | U/kV | AU/D | Z/Ohm | AZ/D | t/s |

| | |L1,2,3 | |L1,2,3 | | 120 | 120 | |

|-----------------------------------------------------------------------|

|DSR-5 | 1| 0.247| 75.3| 4.205| 110.6| 5.08| 18.7|0.600|

| | | 0.022| -69.6| 37.680| 198.9| 5.08| 18.7| |

| | | 0.026| 233.4| 43.799| 143.1| 19.93| 43.7| |

| | |- 120 -|------|- 120 -|------| X/Ohm | R/Ohm|-----|

| | | 0.096| 76.6| 22.433| -3.1| 1.62| 4.81| |

| | | 0.083| 74.6| 0.874| -78.9| 1.62| 4.81| |

| | | 0.068| 74.4| 24.792| 165.9| 13.78| 14.40| |

|-----------------------------------------------------------------------|

|DSR-41 | 2| 0.158| 77.6| 5.647| 109.8| 11.07| 17.1|1.200|

| | | 0.045| -71.3| 37.783| 198.4| 11.07| 17.1| |

| | | 0.051| 237.0| 44.241| 143.1| 40.91| 40.3| |

| | |- 120 -|------|- 120 -|------| X/Ohm | R/Ohm|-----|

| | | 0.079| 80.2| 22.348| -2.0| 3.26| 10.58| |

| | | 0.055| 75.7| 0.554| -75.2| 3.26| 10.58| |

| | | 0.024| 73.6| 25.281| 164.8| 26.45| 31.21| |

|-----------------------------------------------------------------------|

|DSR-42 | 2| 0.086| 74.1| 5.647| 109.8| 21.69| 21.7|3.000|

| | | 0.024| -69.5| 37.783| 198.4| 21.69| 21.7| |

| | | 0.029| 226.3| 44.241| 143.1| 71.96| 44.1| |

| | |- 120 -|------|- 120 -|------| X/Ohm | R/Ohm|-----|

| | | 0.044| 76.7| 22.348| -2.0| 8.01| 20.16| |

| | | 0.028| 70.7| 0.554| -75.2| 8.01| 20.16| |

| | | 0.014| 73.3| 25.281| 164.8| 50.06| 51.70| |

|-----------------------------------------------------------------------|

Fig. 10.5 Evaluation according to fault location

Distance Protection


The abbreviations are:

Fault location: Name of fault location DP-Relay: Name of relay, whose results are listed. Di: Distance of the relay location from the fault location. I: Current (phase and symmetrical component values) in kA,

which flows through the relay when short circuit occurs in the fault location.

AI: Angle of current in degree, which flows through the relay when short circuit occurs in the fault location.

U: Voltage (phase and symmetrical component values) in kV at relay location when short circuit occurs in the fault location.

AU: Angle of voltage in degree at relay location when short circuit occurs in the fault location.

Z: Impedance (symmetrical component value) in Ohm, which is seen from the relay when short circuit occurs in the fault location.

AZ: Angle of impedance in degree, which is seen from the relay when short circuit occurs in the fault location.

R: Resistance (symmetrical component value) in Ohm, which is seen from the relay when short circuit occurs in the fault location.

X: Reactance (symmetrical component value) in Ohm, which is seen from the relay when short circuit occurs in the fault location.

t Tripping time of the relay. All values are given as primary values.

Distance Protection


Evaluation According to Relay Location The same is to say as in the previous section. The list is relay-oriented and is shown above:

+-----------------------------------------------------------------------+

| |

| Relay : DSR-41 |

| Relay location : ONODE 1 |

| To node : ONODE 2 |

| Branch : L-002 |

| |

|-----------------------------------------------------------------------|

|Fault location |Di| I/kA | AI/D | U/kV | AU/D | Z/Ohm | AZ/D | t/s |

| | |L1,2,3 | |L1,2,3 | | 120 | 120 | |

|-----------------------------------------------------------------------|

|ONODE 1 | 0| 0.230| 86.3| 0.000| 0.0| 0.00| 0.0|0.100|

| | | 0.040| -61.1| 38.391| 207.1| 0.00| 0.0| |

| | | 0.042| 236.9| 39.723| 148.1| 0.00| 0.0| |

| | |- 120 -|------|- 120 -|------| X/Ohm | R/Ohm|-----|

| | | 0.100| 86.9| 22.428| -1.8| 0.00| 0.00| |

| | | 0.076| 85.7| 0.506| -63.7| 0.00| 0.00| |

| | | 0.053| 86.0| 22.671| 177.0| 0.00| 0.00| |

|-----------------------------------------------------------------------|

|ONODE 2 | 1| 0.149| 85.4| 1.344| 115.9| 3.38| 18.8|0.100|

| | | 0.045| -64.9| 38.320| 205.0| 3.38| 18.8| |

| | | 0.047| 241.0| 40.852| 147.0| 9.11| 39.1| |

| | |- 120 -|------|- 120 -|------| X/Ohm | R/Ohm|-----|

| | | 0.076| 86.6| 22.412| -1.9| 1.09| 3.20| |

| | | 0.051| 84.7| 0.515| -66.2| 1.09| 3.20| |

| | | 0.022| 82.9| 23.319| 174.1| 5.75| 7.06| |

|-----------------------------------------------------------------------|

|AU_BB12 | 2| 0.158| 77.6| 5.647| 109.8| 11.07| 17.1|1.200|

| | | 0.045| -71.3| 37.783| 198.4| 11.07| 17.1| |

| | | 0.051| 237.0| 44.241| 143.1| 40.91| 40.3| |

| | |- 120 -|------|- 120 -|------| X/Ohm | R/Ohm|-----|

| | | 0.079| 80.2| 22.348| -2.0| 3.26| 10.58| |

| | | 0.055| 75.7| 0.554| -75.2| 3.26| 10.58| |

| | | 0.024| 73.6| 25.281| 164.8| 26.45| 31.21| |

|-----------------------------------------------------------------------|

Fig. 10.6 Evaluation according to relay location

Distance Protection


The abbreviations are:

Relay: Name of relay, whose results are listed. Fault location: Name of fault location Di: Distance of the relay location from the fault location. I: Current (phase and symmetrical component values) in kA,

which flows through the relay when short circuit occurs in the fault location.

AI: Angle of current in degree, which flows through the relay when short circuit occurs in the fault location.

U: Voltage (phase and symmetrical component values) in kV at relay location when short circuit occurs in the fault location.

AU: Angle of voltage in degree at relay location when short circuit occurs in the fault location.

Z: Impedance (phase and symmetrical component values) in Ohm, which is seen from the relay when short circuit occurs in the fault location.

AZ: Angle of impedance in degree, which is seen from the relay when short circuit occurs in the fault location.

R: Resistance (phase and symmetrical component values) in Ohm, which is seen from the relay when short circuit occurs in the fault location.

X: Reactance (phase and symmetrical component values) in Ohm, which is seen from the relay when short circuit occurs in the fault location.

T Tripping time of the relay. All values are given as primary values. Additionally the relay location, the protected element and its ending node are listed. The branch impedance in Ohm is also given. The factor k0 (amount, angle) gives the complex ratio between the branch impedances of the zero sequence and the positive sequence system.

Distance Protection


Harmonic Analysis


Harmonic Analysis

Calculation Parameters (HA)

The calculation parameters are entered with the help of a "Parameters" dialog. It consists of the three tabs Frequency Scanning, Harmonic Level Calculation and Options, which are explained here.

Frequency scanning Frequency scanning

Frequency scanning

Indicates, if Frequency scanning will be done when selecting the calculation.

Frequency start

Starting frequency for the calculation in Hz.

Frequency end

Ending frequency for the calculation in Hz.

Frequency step

Frequency step for the calculation in Hz (see "Theory of Harmonic and Audio Frequency Analysis" on page 11-3).

Variable step length control

If active, the frequency step will be adjusted automatically during impedance calculation if large impedance changes occur. If not active, the impedances are calculated with given and constant step.

Scanning according to

Frequency scanning can be done according to • Z: Scanning a node impedance • I: Scanning a current of one harmonic current source (only

one must be present and active in the network) • U: Scanning a voltage of one harmonic voltage source (only

one must be present and active in the network).

Harmonic Load flow Harmonic load flow calculation

Indicates, if a Harmonic Load flow will be done when selecting the calculation.

Harmonic for Harmonic load flow

The harmonic for which the load flow must be calculated.

Harmonic Analysis


Harmonic Level Calculation

Harmonic Level calculation

Indicates, if Harmonic level calculation will be done when selecting the calculation.

Harmonic limit All harmonics in the harmonic current and voltage sources are considered up to the given limit.

S for THDi calculation

Apparent power in MVA for calculating the nominal current of the elements. The nominal current of the elements are used for calculation the distortion factor THDi.

Sum of harmonic values Vectorial If there are several harmonic sources in the network the sum of

harmonics will be calculated vectorial (see below). Geometric If there are several harmonic sources in the network the sum of

harmonics will be calculated geometrically (see below). IEC 1000-2-6 If there are several harmonic sources in the network the sum of

harmonics will be calculated according to IEC 1000-2-6 (see below).

Arithmetic If there are several harmonic sources in the network the sum of harmonics will be calculated arithmetically (see below).

Options

Reduction of switches circuit breakers and couplers Reduce If this option is checked, all switches, circuit breakers and

busbar couplers are reduced. Result file File File name, which can be selected. Write after calculation

If checked, the result file will be created after the calculation.

Format 4.x If checked, the result file will be created as in program version 4.x.

Select To select the nodes and elements, whose variable should be stored and displayed.

Harmonic Analysis


Theory of Harmonic and Audio Frequency Analysis

The operating behavior of the networks at frequencies above 50/60 Hz has to be simulated in order to examine the harmonics as well as the level of AF ripple control signals in power networks. The following models are required:

• Network elements (lines, filters, loads, synchronous machines..) • Harmonic sources (converter, AF ripple control transmitters...)

Network elements The network elements are represented by their equivalent circuit elements: resis-tance (R), inductance (L) and capacitance (C). A balanced three-phase system is assumed, so that a single-phase representation of the network in the positive sequence system will be examined. In general the resistances and inductances of the network elements are frequency-dependent (see “Frequency dependence” in chapter “Element Data Input and Models”), for example by current displacement (skin effect). In general the resistances are increasing with higher frequencies and the inductances are decreasing. The capacitances are practically frequency-independent. The frequency-dependency of the elements can be entered in three different manners. For all frequencies the resistance and the inductance of the equivalent circuit have to be recalculated.

Sources There is a difference between current and voltage sources. Current sources inject the source current into the network. Voltage sources engrave a source voltage on the network node. The sources are need to reproduce the

• equipment with non-linear current-voltage-characteristic • AF ripple control transmitters.

Sources with non-linear current/voltage characteristics are for example converter and arc furnaces. As a rule these equipments are represented by a current source for harmonics. The harmonic currents with their frequencies, amplitudes and phase angles depend on the construction and operation of these equipments. In case of an arc furnace these are statistic values depending on the particular furnace. In ideal case the harmonic currents of converters can be calculated as following:

Ik

Ik = ⋅1

1

Harmonic Analysis


with: k n p= ⋅ ±1; n = 1 2 3, , ,.... It means: Ik: k-th harmonic current I1: first harmonic current p: pulse number of converter

For details there are more information in the literature. AF ripple control transmitters inject a voltage or current with a well-known frequency in the network. There are two possibilities in coupling the parallel injection and the series injection.

Calculation Algorithm For a harmonic calculation the following steps for each interesting frequency will be made:

• Determination of the equivalent-circuit elements R (f), L(f) (frequency dependent) and C.

• Creating of the admittance matrix for the network • Solution of the linear equation system I(f)=Y(f) · U(f)

It means: I(f): vector of node currents at frequency f Y(f): Y-matrix at frequency f U(f): vector of node voltages at frequency f

For harmonic or AF ripple control calculation the harmonic generators or the AF ripple control transmitters are represented by their equivalent circuits (current or voltages sources). For impedance calculation the program will take a fictious current source (1.0 pu) for the interesting node. A constant amplitude, a constant phase angle and a frequency range will be related to the source. For all frequencies in this range the program calculates the voltage at the interesting nodes. With the ratio of voltage and current for all frequencies the program calculates the impedances (amount and angle). The impedance calculation is made with the following frequencies, which will be calculated with the calculation parameters.

f fanf k fdelta fendk = + ⋅ ≤

It means:

Harmonic Analysis


fk: k-th harmonic, k = 0, 1, 2, ... If the corresponding check box in the calculation parameter mask is checked, the program will examine the amount and the angle of the impedance for large differ-ences between two successive frequency steps. If large differences occur the frequency step will be automatically adjusted according to following formulas:

K ZZ

alt

neu1 5= ⋅ log

K alt neu2 0 05= ⋅ −. ϕ ϕ

If it is valid K1 > 2, that means Zold / Znew > 2,5 or Zold / Znew < 0,4 or K2 > 2, that means °>− 40neualt ϕϕ ,

the automatic frequency adjustment occurs. K will be set to the larger value of K1 and K2:

K = Maximum (K1, K2). With this value the new frequency step will be calculated

fdelta fdeltaK

=

As soon as the condition

K > 2

is no more fulfilled, the frequency step will be calculated according to the user’s input with fstep. It means: Zold: impedance value (amount) at old frequency Znew: impedance value (amount) at new frequency Phiold: angle of impedance at old frequency Phinew: angle of impedance at new frequency.

Harmonic Analysis


Addition of harmonics from different sources In reality harmonics add always vectorial to each other. So, the sum of two harmonic sources (voltage or current) with equal amplitude can vary considerably: between 0% and 200%. The problem is that in practice the harmonic angles in the sources are unknown. Therefore there are four different ways to make the addition of harmonics, which come from different sources: - vectorial - geometrically - according to IEC 1000-2-6 - arithmetically

For each harmonic source and each harmonic the network equation

)()()( fUfYfI •= will be solved. The angle given in the harmonic sources are not considered for all calculations, except for vectorial sum calculation. After having calculated all voltages for each source and harmonic the sum can be built: Vectorial The sum is built up vectorial: ...321 +++= hhhh UUUU Geometrically

The sum is built up geometrically: ...23

22

21 +++= hhhh UUUU

IEC 1000-2-6 The sum is built up according to IEC-1000-2-6: ...332211 +⋅+⋅+⋅= hhhh UkUkUkU

Arithmetically The sum is built up arithmetically: ...321 +++= hhhh UUUU

The abbreviations are: Uh: Node voltage for harmonic h Uh1: Node voltage for harmonic h caused by harmonic source 1 Uh2: Node voltage for harmonic h caused by harmonic source 2 Uh3: Node voltage for harmonic h caused by harmonic source 3 k1: Diversity factor for harmonic h and harmonic source 1 k2: Diversity factor for harmonic h and harmonic source 2 k3: Diversity factor for harmonic h and harmonic source 3

Harmonic Analysis


The size of ki is dependent on the harmonic order h and the ratio between the node voltage Uhi caused by the single harmonic source i and the arithmetically calculated node voltage Uh. For further information please refer to IEC 1000-2-6. The vectorial sum is mathematically the correct one, but because of unknown angles of the harmonics maybe in practice very incorrect. The geometrical sum gives the smallest value, the arithmetical sum the highest value. If the node voltage for the h-th harmonic is known the harmonic currents for all branches can be calculated.

Characteristics The following characteristics are important for harmonic analysis:

• percentage harmonic voltage uk of the h-th harmonic

3n

hh U

Uu =

It means: Uk: r.m.s.-value of the k-th harmonic voltage (phase-to-earth) Un: nominal system voltage

• r.m.s-value of power frequency voltage (geometrical sum):

...23

22

21 +++= UUUU

• r.m.s-value of power frequency current (geometrical sum):

...23

22

21 +++= IIII

• r.m.s-value of harmonic voltage (geometrical sum):

...24

23

22 +++= UUUU

• r.m.s-value of harmonic current (geometrical sum):

...24

23

22 +++= IIII

• Voltage Distortion Factor in %:

Harmonic Analysis


%100....

1

23

22 ⋅

++=

UUU

THD with U1 = Un

• Current Distortion Factor in %:

%100....

1

23

22 ⋅

++=

III

THDi with THDi

nn

SUUI ⋅=1

• TIF:

( )

1

2

IWI

TIF hh∑ ⋅= with

THDi

nn

SUUI ⋅=1 and Wh=5⋅Ph⋅h⋅fn

• IT:

( )2∑ ⋅= hh WIIT

It means: U1: amount of voltage of first (fundamental) harmonic U2: amount of voltage of second harmonic U3: amount of voltage of third harmonic I1: amount of current of first (fundamental) harmonic I2: amount of current of second harmonic I3: amount of current of third harmonic STHDi: input value (see calculation parameters) Wh: single frequency TIF weighting factor at frequency f = h⋅fn according to

IEEE 519 fn: nominal system frequency h: harmonic Ph: C message weigthing factor at frequency f = h⋅fn according to IEEE 519

Filter characteristics Three types of filters can be defined (see description of filter dialog): - normal filter - HP-filter - C-filter. The following values are calculated for filters: IL(FH) fundamental harmonic (nominal system frequency fn) current value

Harmonic Analysis


of the inductance L +IL(RMS): rms current value of the inductance L. +IL(ari): total current value (calculated arithmetically) of the inductance L. IC(FH): fundamental harmonic (nominal system frequency fn) current value

of the main capacitance C +IC(RMS): rms current value of the main capacitance C. +IC(ari): total current value (calculated arithmetically) of the main

capacitance C. Ird(FH): fundamental harmonic (nominal system frequency fn) current value

of the damping resistance Rd. Ird(RMS): rms current value of the damping resistance Rd. PRd(FH): fundamental harmonic (nominal system frequency fn) resistive

losses in kW in the damping resistance Rd. PRd(tot): total resistive losses in kW in the damping resistance Rd caused by

Ird(RMS), PRd(tot) = 3·Rd·Ird(RMS)2 PL(tot): total resistive losses in kW in the reactor caused by caused by

IL(RMS), PL = 3·Rv·IL(RMS)2 UCsu: Arithemic sum of fundamental harmonic voltage and r.m.s-value of

harmonic voltage at auxiliary capacitance Cs (only for C-filters).

∑+= 21 hUCsUCsUCsu for h = 2, 3, …

UCsi: Minimum rated capacitance voltage at which ICs can be transmitted (IEC 871). ICs is 1.3 times the current at nominal system frequency fn, which is calculated if UCsi is applied at the auxiliary capacitance Cs (only for C-filters).

CsfICsUCsi

n ⋅⋅⋅⋅=

π23.1

UCsq: Voltage at nominal system frequency fn, which causes the same reactive power at the auxiliary capacitance Cs, as the arithmetic sum of all reactive powers caused by the nominal system frequency and the harmonic frequencies (only for C-filters).

∑ ⋅⋅= 20 hUCsfhUCsq for h=1, 2, 3,…

UCu: Arithemic sum of fundamental harmonic voltage and r.m.s-value of harmonic voltage at main capacitance C.

∑+= 21 hUCUCUCu for h = 2, 3,…

UCi: Minimum rated capacitance voltage at which IC can be transmitted (IEC 871). IC is 1.3 times the current at nominal system frequency fn, which is calculated if Uci is applied at the main capacitance C.

Harmonic Analysis


CfICUCi

n ⋅⋅⋅⋅=

π23.1

UCq: Voltage at nominal system frequency fn, which causes the same reactive power at the main capacitance C, as the arithmetic sum of all reactive powers caused by the nominal system frequency and the harmonic frequencies.

∑ ⋅⋅= 20 hUCfhUCq for h=1, 2, 3,…

Harmonic Analysis


Results (HA)

Select Results The nodes and elements to be presented in the result table, may be selected here. The values displayed at the diagram can be selected in the Harmonic Analysis tab of the “Edit – Diagram Properties” dialog.

Results Table The results can be represented in different tables, each with its specifique information.

Node impedances The node impedances are shown for the pre-selected nodes. This is a result getting from a frequency scanning Z-impedance.

Node results The results of the nodes will be displayed. This is a result of either a frequency scanning U/I or a level calculation or or a harmonic load flow.

Element results General results of elements will be displayed. This is a result of either a frequency scanning U/I or a level calculation or a harmonic load flow.

Filter results All results of the filters will be displayed. This is a result of a level calculation.

Result files It’s possible to export results to a *.ros file by selecting the file and pressing the respective button. These result files can be read by external programs, such as Excel and the results can be evaluated in an arbitrary way. The File can be written in the old Format 4.x or in a new Format for V5.x.

Below you find a description of the output variables in the result tables: Node impedances:

f Frequency in Hz.

Harmonic Analysis


Z Impedance in Ohm. Z ang Angle of impedance in °.

Node results:

ID Identification number (ID) of the node. Name Node name. THD Distortion factor in %. f Frequency in Hz. U Node voltage in V (line-line value) u [%] Node voltage in % in respect to nominal node voltage. U ang Voltage angle in °. Description Description of the node. Zone Zone, the node belongs to. Area Area, the node belongs to. Partial network


Element results:

ID Identification number (ID) of the element. From Name of starting node of element (From node) To Name of ending node of element (To node) Element name Name of the element. Type Type of element. THDi Current distortion factor in %. TIF TIF factor. IT IT factor. F Frequency in Hz. I1, I2, I3 Current at “From node”, “To node”, “Tertiary node” in A. I1ang, I2ang, I3ang

Current angle at “From node”, “To node”, “Tertiary node” in °.

U12, U31, U23 Voltage (line-line values) between “From node” and “To node” and “Tertiary node” in V.

U12ang, U31ang, U23ang

Angle of voltages between “From node” and “To node” and “Tertiary node” in °.

Description Description of the element.

Harmonic Analysis


Zone Zone, the element belongs to. Area Area, the element belongs to. Partial Network Number of the partial network, the element belongs to.

Filter results: Please see section “Filter characteristics”.

Graphical Results To open the graphical result window choose "Analysis – Harmonic Analysis - Graphical Results...".

Subchart settings:

Chart name Name of chart. Add, Edit Delete curve

Push buttons to add, edit and delete curves in the diagram.

Harmonic Analysis Results Curve name Name of curve Variant Name of Variant or Rootnet. Variable name The variable name can be selected. Three options are

available: - Nodes variable - Elements variable - Level limit curve.

Element name, ID Name of element, whose results are displayed. Variable Variable to be displayed. File path File name and path for limit curve. Limit curve Limit curve to be displayed. In the file several curves can

be stored. To display all curves in the file, please add new curve.

Axis properties Select axis Select axis whose settings have to be displayed / changed. Title Axis title. Only enabled if the corresponding check box

“Automatic” is not checked. Resolution Specifies the resolution of the steps in between labels.

Only enabled if the corresponding check box “Automatic” is

Harmonic Analysis


not checked. No of digits Number of label digits. Only enabled if the corresponding

check box “Automatic” is not checked. Min Sets the axis minimum value. Only enabled if the

corresponding check box “Automatic” is not checked. Max Sets the axis maximum value. Only enabled if the

corresponding check box “Automatic” is not checked. Grid If checked grid lines are displayed. Legend Show legend If checked, legend will be displayed Height Height of legend in % of sub chart size

The format of the current limit file is given in the appendix.

Motor Starting


Motor Starting

Calculation Parameters (MS)

The calculation parameters are entered with the help of a "Parameters" dialog, which is explained here. Time simulation End time End time for the simulation in s. Time interval Time interval for the simulation in s. Reduction factor for time interval

Factor for reducing the time interval. During the simulation, the time interval will be reduced by this factor, when the motor slip s will be less than 0.2. After reaching the steady state point the time interval will be reset to entered value.

Transformer regulation considered after time

Time delay for regulating transformers in s. After the given time the automatic regulation of the transformers will be activated. This value is only important, if the parameter "Automatic transformer regulation” is checked in the load flow parameters.

Result storage Points to be saved per variable

The user can enter the number of points to be saved for the marked elements during the simulation. In this way the graphical output will be influenced (layout and speed).

Result display Result display Output units. For low voltage in "V, A, kVA" or high voltage in

"kV, kA, MVA". Only the results of the pre-selected nodes and elements are stored and can be displayed. The selection can be done with the menu option “Analysis – Motor Starting – Select results” or the push button “Select results”. The motor starting is dependent on the parameters set in the load flow. To change load flow parameters press push button “LF-parameters”.

Motor Starting


Theory of Motor Starting Calculation

The motor starting simulation is a sequence of load flow calculations. In every calculation resp. time step (load flow) the impedance of the asynchronous machine will be changed in function of the increasing speed and resistance (eddy-current losses) as well as the leakage reactance (decreasing of the saturation). The theory of the load flow calculation is explained section "Theory of Load Flow Calculation" in chapter "Load Flow". The equivalent circuit of an asynchronous machine is given below:

R2(s)/s

X2(s)

Xh

R1 X1

Fig. 12.1 Asynchronous machine equivalent circuit

For more information about this model see “Asynchronous Machine – Model” of the chapter “Element Data Input and Models”. To consider the voltage drop at the terminal of an infeed element (generator, feeder, power system unit) the following model will be used:

XdNetw. node Dummy node

Fig. 12.2 Equivalent circuit of an infeed element For every infeed element a dummy node will be created. Between the real network node and the dummy node the reactance Xd = 1.5 * Xd" (Xd":

Motor Starting


subtransient reactance) will be inserted. The reactance Xd" can be calculated from the input values. The dummy nodes are named by the program. Their names start with the character "@". The type of the network node (SL, PQ or PV) will be automatically assigned to the dummy node and the network node will become a normal PQ-node. The voltage of the network node is free adjustable and will be calculated by the program. The start-up of a motor will be described by the motion equation:

Me - Ml = - 2 · Pi · J · n0 / p · ds/dt

with Me: Electromagnetic torque Ml: load torque J: moment of inertia n0: synchronous speed p: numbers of pole pairs s: Slip

The electromagnetic torque is described by the equation:

Me = p / (2 · Pi · n0) · R2 · I22 / s

with I 2: rotor current in circuit (R2, X2)

The load torque is described by the equation: Ml = M0 + (1 - s) · M1 + (1 - s) 2 · M2 (parabola) or Ml = Ml(s) (characteristic) with M0, M1, M2: input values (see "Theory of Motor Starting Calculation" on page

12-2) Ml(s): starting load characteristic, input values as well (see "Theory of

Motor Starting Calculation" on page 12-2) If a motor will not be started-up, the steady state point will be

• calculated with the help of the operating load and the electromagnetic torque ("LF-Type" must be set to "Mload")

Motor Starting


• set as constant power load P and Q ("LF-Type" must be set to "PQoper").

The calculation of the steady state point with the help of the load characteristic consists also of a sequence of load flow calculations. The steady state point that means the crossing of the torque curves will be calculated with the Newton-Raphson algorithm.

Voltage Drop Selecting the corresponding menu option the voltage drop at time t=0.0 due to starting motors is calculated. The calculation will be done as explained in section "Theory of Motor Starting Calculation" on page 12-2. The difference is, that less data have to be entered for the motors. For example the moment of inertia J, all time data, load characteristics can be dropped.

Motor Starting


Results (MS)

Select Results The nodes and elements to be presented in the result table, may be selected here.

Results tables The results are represented in a table.

ID Identification number (ID) of the node. Name Name of node or element. t Simulation time in s. U Node voltage in kV at time t. I Current in kA of the element at time t. P Active power in MW of the element at time t. Q Reactive power in Mvar of the element at time t. Me Electrical machine torque in Nm at time t. Ml Load torque in Nm at time t. s Machine slip at time t. n/nr Ratio between rotor speed at time t and nominal speed.

Graphical Results To open the graphical result window choose "Analysis – Motor Starting - Graphical Results...".

Subchart settings:

Chart name Name of chart. Add, Edit Delete curve

Push buttons to add, edit and delete curves in the diagram.

Motor Starting


Motor Starting Results Curve name Name of curve Variant Name of Variant or Rootnet. X-Axis variable Time If checked, the x-axis is always the time axis. If not

checked, all selection as for Y-axis are possible. Y-Axis variable Element type Type of Element. Three options are available:

- Asynchronous machine - Element - Node

Element name, ID Name of element, whose results are displayed. Only the pre-selected nodes or elements are displayed.

Variable Variable to be displayed. Axis properties Select axis Select axis whose settings have to be displayed / changed.Title Axis title. Only enabled if the corresponding check box


Only enabled if the corresponding check box “Automatic” is not checked.

No of digits Number of label digits. Only enabled if the corresponding check box “Automatic” is not checked.

Min Sets the axis minimum value. Only enabled if the corresponding check box “Automatic” is not checked.

Max Sets the axis maximum value. Only enabled if the corresponding check box “Automatic” is not checked.

Grid If checked grid lines are displayed. Legend Show legend If checked, legend will be displayed Height Height of legend in % of sub chart size

Network Reduction


Network Reduction

Introduction

This program module allows to reduce any network to any number of boundary nodes, thus the behavior of the reduced network will be the same as the original one. This is for short circuit and load flow calculation. The reduced network will be represented with the help of series (see "Series Equivalents Data" in chapter "Element Data Input and Models") and shunt (see "Shunt Equivalents Data" in chapter "Element Data Input and Models") equivalents as well as equivalent infeeds. Depending on the type of network reduction there are equivalents for short circuit and for load flow. The same equivalent can't be valid for load flow and short circuit.

Selection of the Network to be Reduced

The selection of the network to be reduced, respectively the nodes is independent of the type of network reduction (load flow or short circuit). The node to be reduced can be selected after having chosen the menu option "Analysis - Network reduction - Network selection (LF)" (for load flow) or "Analysis - Network reduction - Network selection (SC)" (for short circuit). All nodes, which are selected in the list will be reduced for the corresponding calculation. When quitting the dialog box, the boundary nodes are set automatically.

Network Reduction


Network Reduction for Load Flow

A network will be reduced after having selected "Analysis - Network reduction -Load flow". All nodes to be reduced will be erased from the project and the series- and shunt equivalents as well as the equivalent infeeds or loads are generated. The generated equivalents can be listed in the variant manager. The graphical representation of these equivalents can be done as usual. The reduced network has the same behavior with respect to the load flow as the original network. If the original network should not be overwritten, the reduced network must be stored with an other file name.

Important remarks: 1. Boundary nodes are represented as PQ-nodes without voltage control. The

node type and/or the voltage control become active if there is a synchronous machine connected to the boundary node.

2. Reduced automatically regulated tap changing transformers have no influ-ence on changes in the reduced network. If the influence should be consid-ered the initial and ending node of these transformers should not be reduced.

Network Reduction for Short Circuit

A network will be reduced after having selected "Analysis - Network reduction -Short circuit". All nodes to be reduced will be erased from the project and the series- and shunt equivalents as well as the equivalent infeeds or loads are generated. The generated equivalents can be listed in the variant manager. The graphical representation of these equivalents can be done as usual. The reduced network has the same behavior with respect to the short circuit as the original network. The network can be reduced dependent on the short circuit parameters for differ-ent short circuit faults and short circuit methods (see "Short Circuit Parameter" in chapter "Short Circuit"):

Short circuit type: 3-phase short circuit Only the matrix of the positive system will be built up and reduced. In the reduced network only 3-phase short circuit can be calculated.

Network Reduction


Asymmetrical short circuit The matrices of the positive, negative and zero system will be built up and reduced. In the reduced network any kind of short circuit can be calculated.

Short circuit methods: IEC909 The nodal admittance matrix will be built up and reduced according to IEC909. In the reduced network only short circuits according to the mentioned method should be calculated (see "Theory of Short Circuit Calculation" in chapter "Short Circuit"). Superposition method The nodal admittance matrix will be built up and reduced according to superposi-tion method. In the reduced network only short circuits according to the mentioned method should be calculated (see "Theory of Short Circuit Calculation" in chapter "Short Circuit"). ANSI/IEEE The nodal admittance matrix will be built up and reduced according to ANSI/IEEE method. In the reduced network only short circuits according to the mentioned method should be calculated (see "Theory of Short Circuit Calculation" in chapter "Short Circuit"). If the original network should not be overwritten, the reduced network must be stored with an other file name.

Voltage Stability


Voltage Stability


To change the voltage stability calculation options, select "Analysis - Voltage Stability - Parameters..." from the menu.

Sensitivity Analysis / Modal Analysis

Enable U-Q sensitivity analysis

S Enable U-Q sensitivity analysis for voltage stability calculation

Enable Q-U modal analysis M Enable Q-U modal analysis for voltage stability calculation

Options Buses without load elements

M Q=0, constant: reactive power variation of buses without connected load elements is zero. Q variable: reactive power of buses without connected load elements is variable.

Maximum number of eigenvalues

M Maximum number of stored eigenvalues

Limits for sensitivities / participation factors

S, M Values smaller than % of the maximum value arent stored.

Results Mutual bus sensitivities S Not only the bus self sensitivities ii QU ∂∂ / ,

but also the mutual bus sensitivities ik QU ∂∂ / are stored.

Bus participation factors M Bus participation factors are stored. Branch participation factors M Branch participation factors are stored. Generator participation factors

M Generator participation factors are stored.

Eigenvectors M Eigenvectors are stored. S: used by sensitivity analysis M: used by modal analysis

Voltage Stability


U-Q Curves

Enable computation of U-Q curves

Enable computation of U-Q curves for voltage stability analysis

Voltage interval Lower limit First point of U-Q curves Upper limit Last point of U-Q curves Increment Distance between 2 points Sign convention for reactive power

Determines if reactive power injection or reactive power consumption is positive

Select nodes Select nodes whose U-Q curves have to be computed.

P-U Curves

Enable computation of P-U curves

Enable computation of P-U curves for voltage stability analysis

Load scaling factor Lower limit First point of P-U curves Upper limit Last point of P-U curves. Set to a high value (e.g. 106) if

the voltage collapse point has to be the last point. Initial increment Maximum distance between 2 points, increment at the

beginning of the simulation Final increment Minimum distance between 2 points, increment at the

voltage collapse point. The increment is automatically adjusted from Initial increment to Final increment

P-U computations List of defined P-U computations Identifier Name of computation Loads Number of selected loads to be scaled Generators Number of selected generators to be scaled Buses Number of bus voltages to be recorded New Insert a new item into the computation list

Voltage Stability


Delete Delete the selected item from the list Select All Enable all items Select None Disable all items Elements Determine for the selected item the loads and the

generators to be scaled and the bus voltages to be recorded.

The voltage stability analysis can be started selecting "Analysis - Voltage Stability - Calculation" from the menu. To perform voltage stability analysis for a partial network choose "Analysis - Voltage Stability - Partial Network...".

Result Files

File name File name or full file path name Select full path name Build after calculation File is automatically built after calculations Build export file File is built.

Voltage Stability


Results

Graphical Results To open the graphical result window choose "Analysis - Voltage Stability - Graphical Results...".

Subchart settings:

Subchart type Select results to be displayed Add curves manually

If checked, curves have to be added using the tab Curves. If not checked, tab Curves isnt visible and curves of the actual variant are automatically added according to the following 4 subchart settings.

Select eigenvalue Eigenvalue selection (for participation charts) Select bus Bus selection (for mutual bus sensitivity chart) Select U-Q curves Select U-Q curves to be displayed (for U-Q curve chart) Select P-U curves Select P-U curves to be displayed (for P-U curve chart) Axis properties Select axis Select axis whose settings have to be displayed / changed.Title Axis title. Only enabled if the corresponding check box

Automatic is not checked. Resolution Specifies the resolution of the steps in between labels.

Only enabled if the corresponding check box Automatic is not checked.

No of digits Number of label digits. Only enabled if the corresponding check box Automatic is not checked.

Min Sets the axis minimum value. Only enabled if the corresponding check box Automatic is not checked.

Max Sets the axis maximum value. Only enabled if the corresponding check box Automatic is not checked.


Voltage Stability


The tab Curves is visible only if Add curves manually is checked. Press the Add Curve button to add a new curve to the subchart. Press the Edit Curve button to change the settings of the selected curve.

Curve settings:

Curve name Curve name used for the legend. This field is enabled only if Create name automatically is not checked.

Create name automatically

Create curve name automatically

Variant Select variant P-U computation Select P-U computation. Enabled only for P-U curve

charts. Node name, ID Select node. Enabled only for mutual bus sensitivity charts,

U-Q curve charts and P-U curve charts. Eigenvalue Select eigenvalue. Enabled only for participation charts.

Result Tables To open the result tables choose "Analysis - Voltage Stability Result Tables". The result tables display all calculated and stored numerical results.

Voltage Stability


Theory

Introduction

The analysis of voltage stability can be done using two different methods, time simulations and static methods. Time simulations capture the events and their chronology leading to instability. The computer tries to solve the differential equations describing the power system. Time simulations are useful for detailed study of specific voltage collapse situations and coordination of protection and controls. The Dynamic Analysis module can be used for such time domain simulations.

Many aspects of voltage stability problems can be effectively analyzed by using static methods, which examine the viability of the equilibrium point represented by a specified operating condition of the power system. The static analysis techniques allow examination of a wide range of system conditions, can provide much insight into the nature of the problem and can identify the key contributing factors. The Voltage Stability module contains 4 static methods: U-Q Sensitivity Analysis, Q-U Modal Analysis, U-Q Curves and P-U Curves. Static voltage stability analysis is based on the conventional load flow model.

U-Q Sensitivity Analysis U-Q sensitivity analysis calculates the relation between voltage change and reactive power change.

∆QJ∆U R ⋅= −1

∆U incremental change in bus voltage magnitude (vector) ∆Q incremental change in bus reactive power injection (vector)

RJ reduced Jacobian matrix

The elements of the inverse of the reduced Jacobian matrix RJ are the U-Q sensitivities. The diagonal components are the self sensitivities ii QU ∂∂ / and the nondiagonal elements are the mutual sensitivities ik QU ∂∂ / . The sensitivities of voltage controlled buses are equal to zero.

Positive sensitivities: Stable operation; the smaller the sensitivity, the more stable the system. As stability decreases, the magnitude of the sensitivity increases, becoming infinite at the stability limit (maximum loadability).

Voltage Stability


Negative sensitivities: Unstable operation. The system is not controllable, because all reactive power control devices are designed to operate satisfactorily when an increase in Q is accompanied by an increase in U.

Q-U Modal Analysis The modal analysis approach has the added advantage that it provides information regarding the mechanism of instability. Voltage stability characteristics of the system can be identified by computing the eigenvalues and eigenvectors of the reduced Jacobian matrix RJ .

ηΛξJR ⋅⋅=

Λ diagonal eigenvalue matrix ξ right eigenvector matrix η left eigenvector matrix

iξ ith right eigenvector, ith column of right eigenvector matrix

iη ith left eigenvector, ith row of left eigenvector matrix

Using modal analysis techniques the original problem (see chapter U-Q Sensitivity Analysis)

∆QJ∆U R ⋅= −1

is transformed into qΛu ⋅= −1

∆Uηu ⋅= vector of modal voltage variations ∆Qηq ⋅= vector of modal reactive power variations

The difference between these two equations is that 1−Λ is a diagonal matrix whereas the reduced Jacobian matrix in general is nondiagonal. The inverse transformation is given by

uξ∆U ⋅= qξ∆Q ⋅=

Positive eigenvalue: The system is voltage stable. The smaller the magnitude, the closer the ith modal voltage is to being unstable. The magnitude of the eigenvalues can provide a relative measure of the proximity to instability.

Zero eigenvalue: The ith modal voltage collapses because any change in that modal reactive power causes infinite change in the modal voltage.

Negative eigenvalue: The system is voltage unstable.

Voltage Stability


Eigenvalues and eigenvectors of the reduced Jacobian matrix for all practical purposes are real. If for Buses without load elements the option Q=0, constant is selected, ∆Q = 0 is introduced for buses without any active bus elements. In this case the variable ∆U of these buses is dependent only on other bus voltage magnitudes and is eliminated.

Bus participation factors: The relative participation of a bus in a certain mode is given by the bus participation factor. Bus participation factors determine the areas with each mode. Thus, voltage weak areas or unstable (not controllable) areas are identified. The sum of all the bus participations for each mode is equal to unity. The size of bus participation in a given mode indicates the effectiveness of remedial actions applied at that bus in stabilizing that mode.

Branch participation factors: The relative participation of branch j in a certain mode is given by the participation factor

[ ]jlossj

jlossj Q

QP

∆∆

=max

Branch participation factors indicate, for each mode, which branches consume the most reactive power in response to an incremental change in reactive load. Branches with high participations are either weak links or are heavily loaded. Branch participations are useful for identifying remedial measures to alleviate voltage stability problems and for contingency selection.

Generator participation factors: The relative participation of machine m in a certain mode is given by the generator participation factor

[ ]mm

mm Q

QP∆

∆=max

Generator participation factors indicate, for each mode, which generators supply the most reactive power in response to an incremental change in system reactive loading. Generator participations provide important information regarding proper distribution of reactive reserves among all the machines in order to maintain an adequate voltage stability margin.

U-Q Curves The U-Q curves are produced by running a series of load flow cases. U-Q curves show the necessary amount of reactive power Q to achieve a specified voltage level U. The minimum point of a U-Q curve (reactive power injection positive) is the critical point, i.e. all points of the curve to the left of the minima are assumed to be unstable. The points to the right of the minima are assumed to be stable. If the minimum point of the U-Q curve is above the horizontal axis, the system is reactive power deficient. Additional infeed of reactive power is required to prevent

Voltage Stability


voltage collapse. If the critical point is below the horizontal axis, the system has some VAR margin. Additional infeed of reactive power is required if a greater margin is desired. Voltage collapse starts at the weakest bus and then spreads out to other weak buses. Therefore the weakest bus is the most important in the voltage collapse analysis using U-Q curve techniques. The weakest bus is one that would exhibit one of the following conditions: a) has the highest voltage collapse point, b) has the lowest reactive power margin, c) has the greatest reactive power deficiency, or d) has the highest percentage change in voltage.

∆Q

Q

U

Fig. 14.1 U-Q curve with VAR margin ∆Q

P-U Curves The P-U curves are produced by running a series of load flow cases. P-U curves relate bus voltages to load within a specified region. The benefits of this methodology are that it provides an indication of proximity to voltage collapse throughout a range of load levels. The nature of voltage collapse is that as power transfers into well-bounded region are increased, the voltage profile of that region will become lower and lower until a point of collapse is reached. The voltages at specific buses in the region can vary significantly, and some specific bus voltage could appear acceptable. The point-of-collapse at all buses in the study region, however, will occur at the same power import level, regardless of the specific bus voltages.

U

P

Voltage Stability


Fig. 14.2 P-U curve

Before the calculation can be run, the following has to be defined: • A set of loads to be scaled • A set of generators to be scaled • A set of bus voltages to be recorded • The load level at the beginning of the simulation • The load increment • The load level at the end of the simulation if the simulation should stop

before the point-of-collapse occurs

Small Signal Stability




To set the calculation options, select "Calculation - Small Signal Stability - Parameters..." from the menu.

Calculation

Eigenvectors Enable calculation of eigenvectors Participation factors Enable calculation of participation factors Limit for participation factors

Percentage of the maximum participation factor: participation factors greater than this value are stored. Set this value to 0 if all participation factors have to be stored.

Eigenvalue sort order Determines the order how eigenvalues are listed in table and file outputs.

Eigenvalue interval Eigenvalues located in this range are stored

Result Files

File name File name or full file path name … Select full path name Build after calculation File is automatically built after calculations Build export file File is built.

The small signal stability analysis can be started selecting "Calculation - Small Signal Stability - Calculation" from the menu. To perform small signal stability analysis for a partial network choose "Calculation - Small Signal Stability - Partial Network...".



Results

Graphical Results To open the graphical result window choose "Analysis – Small Signal Stability - Graphical Results...".

Subchart settings:

Subchart type Select results to be displayed Axis properties Select axis Select axis whose settings have to be displayed / changed.Title Axis title. Only enabled if the corresponding check box


Only enabled if the corresponding check box “Automatic” is not checked.

No of digits Number of label digits. Only enabled if the corresponding check box “Automatic” is not checked.

Min Sets the axis minimum value. Only enabled if the corresponding check box “Automatic” is not checked.

Max Sets the axis maximum value. Only enabled if the corresponding check box “Automatic” is not checked.


Choose the tab “Curves” in order to add or edit curves. Press the “Add Curve” button to add a new curve to the subchart. Press the “Edit Curve” button to change the settings of the selected curve.

Curve settings:

Curve name Curve name used for the subchart legend. This field is enabled only if “Create name automatically” is not checked.

Create name If checked, curve name is automatically created



automatically Variant Select variant Eigenvalue Select eigenvalue. Enabled only for mode shape charts

and eigenvalue participation factor charts. State variable Select state variable. Enabled only for state variable

participation factor charts

Result Tables To open the result tables choose "Analysis – Small Signal Stability – Result Tables". The result tables display all calculated and stored numerical results.



Theory

Introduction Small signal stability is the ability of a power system to maintain synchronism when subjected to small disturbances. Disturbances are said to be small if the equations that describe the resulting response of the system may be linearized for the purpose of analysis. The linear equations are derived from the corresponding nonlinear equations. That is done trough linearization at a specified operating point. An operating point corresponds to a steady-state load flow condition. Eigenvalue analysis (modal analysis) is a valuable tool in analysis of power system small signal stability. It provides information about the inherent dynamic characteristic of the power system and assists in its design. It is typically used in studies of interarea oscillations.

Eigenvalue Theory The linearized state space equations of a nonlinear system are

∆uD∆xC∆y∆uB∆xAx∆

⋅+⋅=⋅+⋅=&

The stability in the small is given by the eigenvalues iλ of the state matrix A . For any eigenvalue iλ , there exists at least one nonzero column vector ir which satisfies

iii rrA ⋅=⋅ λ The vector ir is called a right eigenvector of its eigenvalue iλ . A vector il which satisfies

iiiT llA ⋅=⋅ λ

is called a left eigenvector of its eigenvalue iλ . The stability of a power system is determined by the eigenvalues as follows:

A real eigenvalue corresponds to a non-oscillatory mode. A negative real eigenvalue represents a decaying mode. The larger its magnitude, the faster the decay. A positive real eigenvalue represents aperiodic instability.



Complex eigenvalues occur in conjugate pairs (since the state matrix is real), and each pair correspond to an oscillatory mode. The real component of the eigenvalues gives the damping, and the imaginary component gives the frequency of oscillation. A negative real part represents a damped oscillation whereas a positive real part represents oscillation of increasing amplitude. For a complex pair of eigenvalues ωσλ j±= the frequency of oscillation in Hz is given by

πω2

=f

The damping ratio is given by

22 ωσσζ+

−=

Mode shape A right eigenvector gives the mode shape, i.e., the relative activity of the state variables when a particular mode is excited. For example, the degree of activity of the state variable kx in the ith mode is given by the element k of the right eigenvector ir . The magnitudes of the elements of ir give the extents of the activities of the state variables in the ith mode, and the angles of the elements give phase displacements of the state variables with regard to the mode. Because different system variables have different units, it is inconvenient to compare elements of an eigenvector for different types of variables. Generally, only variables of a same type (e.g rotor speed) are compared.

Participation factor For the kth state variable and the ith eigenvalue, the associated participation factor is calculated by

kikiki rlp ⋅= where kil and kir are the kth entries in left eigenvector il and right eigenvector ir respectively. A participation factor is a measure of the relative participation of the kth state variable in the ith mode, and vice versa. Since kir measures the activity of the state variable k in the ith mode and kil weighs the contribution of this activity to the mode, the product measures the net participation.The effect of multiplying the elements of the left and right eigenvectors is also to make the participation factor dimensionless (i.e. independent of the choice of units).



In view of the eigenvector normalization, the sum of the participation factors associated with any eigenvalue or with any state variable is equal to 1.0 + j 0.0:

01

01

1

1

jp

jp

n

iki

n

kki

+=

+=

∑

∑

=

=

Participation factors are complex values. However, their magnitudes provide enough information for dynamic system analysis.

Algorithm The NEPLAN small signal stability calculation procedure contains the following main steps:

1. Load flow calculation 2. Linearization of the state space equations of all power system elements

(e.g. generators, loads, etc.) 3. Build system state matrix A . 4. Calculation of eigenvalues and eigenvectors using an LR-QR algorithm 5. Calculation of participation factors, etc.

Results are only available if no error occurred.

Transient Stability


Transient Stability

General Remarks

Transient Stability module is a simulation program for computing electro-mechanical transient phenomena in electricity networks. For calculating the electricity network's behavior, all network elements are simu-lated by mathematical models. Synchronous machines and their control circuits are described (in terms of their behavior in non-steady-state operation) by their system equations, which contain algebraic equations and differential equations. In conjunction with the algebraic equations of the network, we thus obtain an equa-tion system representing a mathematical model of the entire network. In addition to the depiction of the primary elements, the Transient Stability module also provides an option for simulating secondary elements (protective equipment). During the simulation process, the measured values of the protective relays are determined and the trip conditions are continuously monitored. Trips, and the as-sociated switching operations, are performed automatically by the program. Ad-justment and monitoring routines for complex protective systems are thus signifi-cantly facilitated. The starting point for each simulation is a steady-state operating condition, which is determined by a load flow calculation beforehand.

Simulation method The simulation method's job in calculating electro-mechanical transient phenom-ena is to simultaneously solve the algebraic equations of the network and the sys-tem equations of the dynamic elements at any one point in time. The algebraic equations of the network are the model equations of the quasi-steady-state elements in the electricity network. These elements are: lines, trans-formers, constant compensators, and loads with constant impedance. The model equations are formed from complex admittances and/or admittance matrices. The model equations for the individual quasi-steady-state elements are put together to form the network admittance matrix YN so as to reflect the network topology. The network admittance matrix is a square matrix with complex matrix elements, with the order of the matrix corresponding to the number of nodes in the network. The matrix equation of the electricity network is thus obtained as

iYu ⋅= −1N

Transient Stability


If the node currents i are known, then the unknown node voltages u can be calcu-lated. During simulation, the network admittance matrix is constant for as long as there are no changes to the topology. The network admittance matrix is altered only by switching operations in response to network disturbances, or in the event of tripping of faults. The inverse of YN is determined by factorizing, and to mini-mize the computation work the sequence of the nodes is specified by dynamic or-dering. The incoming node currents i are the output variables for the system equations of the dynamic elements and are mostly voltage-dependent. Node currents are also caused by loads which do not represent an impedance pure and simple. These node currents, too, are voltage-dependent. The matrix equation of the electricity network is thus non-linear and has to be solved iteratively. System equations are used for all pieces of equipment which are simulated by algebraic and differential equations. The system equations generally read in the state form

uDxCy

uBxAx

⋅+⋅=

⋅+⋅=dtd

As exemplified by the model of the synchronous machine, the input variables u are the d and q axis components of the terminal voltage, the excitation voltage and the turbine's torque. The output variables y are the terminal currents. The cur-rent feeding into the inverted network admittance matrix can be determined by transformation from the fixed-rotor coordinate system into the complex coordinate system of the network equations. The state variables x depend on the model se-lected, and do not have to correspond to physical variables. Laplace transformation of the differential equations of the system equations will produce the following:

X(s) = (sI - A)-1·x0 + (sI - A)-1·B·U(s) A and B are given, x0 is the starting point of the state variables. If the input vari-ables U(s) were also known, then re-transformation into the time domain would produce an accurate solution of the state equations. If the input variables are ap-proximated between two integration points by means of a first-order polynomial (straight line), the following integration formulas are obtained (see [1]) xn+1 = P·xn + W1·un + W2·un+1 xn,un ... Variables at the beginning of the integration interval

Transient Stability


xn+1,un+1 ... Variables at the end of the integration interval The integration method is an implicit single-step method, and is stable for all inte-gration step sizes, irrespective of the sizes of the time constants involved. The integration formula contains one part, which depends only on the variables at the beginning of the interval. This part must be calculated only once per interval, and is then constant during the iterative solution process. The input variables u at the end of the integration interval are estimated at the beginning of the iteration and then continuously improved as iteration proceeds. The coefficient matrices P, W1 and W2 are constant for as long as the integration interval remains unchanged. The coefficient matrices are determined analytically, or by series development, in dependence on the size and the structure of system matrix A. To avoid excessive computation work, the system equations are divided into subsystems, with an order of up to three or four. The subsystems are then solved consecutively, block by block, thus arriving at a solution to the entirety of all system equations within the iterative solution process. The iterative solution process looks like this: a) Start with initial load flow or with the result of the last integration step, estimate

the input variables for the end of the interval. b) Solve the system equations for the dynamic elements and for loads not repre-

senting a constant impedance. Determine the incoming currents I. c) Solve the network equations and calculate the new node voltages d) Check the convergence by comparing the node voltages prior to and after itera-

tion. When convergence has been reached, iteration will be aborted and the next integration interval started. Otherwise continue with iteration at b).

This iterative solution of the network equations and system equations will supply a simultaneous solution for the entire system without any interface error. A control function for the integration's step size is superimposed onto the iteration process described above. The step size is changed in dependence on the devia-tion between the estimated and the actually computed variables for rotor angle and electric active power of synchronous machines. A logic function increases or decreases the step size between specified values. Thanks to this step-width con-trol, the computation work required for a long simulation period can be signifi-cantly reduced.

Transient Stability


Terms and Definitions, Per-Unit System

Terms and Definitions Function block A function block is the smallest function unit of a control circuit. Each function block is described by a transfer function, which forms the output signal(s) from the input signals. A transfer function can be independent of time (algebraic equations only) or dependent on time (algebraic and differential equations). Variable An variable is the analog or binary output variable of a network element which var-ies in time. A variable can be selected for outputting and display, or can serve as input variable for a control circuit or a protective device. The user can change a variable's value by forming absolute values, by negation and/or inversion. Controller signal A controller signal is an analog or binary output of a function block of a control cir-cuit. A controller signal is available as a variable both within the control circuit concerned and outside it as well. Switching operation A switching operation is a change in the state of a network element. There is more than one type of switching operation for each type of element. A switching opera-tion is triggered at a preset point in time by the user or automatically by the trigger function of a protective device.

Per-Unit System Internally, the Transient Stability module calculates with referenced variables, with per-unit variables. The nominal values of the network elements are converted into "per-unit" with the reference power SB and with the reference voltage UB which is specified for each node. Reference power and reference voltages are read in us-ing the LoadFlowFile. Referenced powers Nominal values:

Transient Stability


S j QMVA MVAr[ ] [ ] = P[MW] + ⋅

Per-unit:

s = p + j q⋅ ⇔ S

S = P

S+ j Q

SB B B⋅

Referenced voltages Nominal values:

U j UkV im [kV][ ] = Ure [kV] + ⋅

Per-unit:

u j uim = ure + ⋅ ⇔ U

U = U

U+ j U

UB

re

B

im

B⋅

Referenced currents Nominal values: Reference current:

I j IA im A[ ] [ ] = Ire [A] + ⋅ B

BB U3

S = I⋅

Per-unit:

i j iim = ire + ⋅ ⇔ I

I = I

I+ j I

IB

re

B

im

B⋅

Referenced impedances Nominal values: Reference impedance:

Z j X[ ] [ ]Ω Ω Ω = R[ ] + ⋅ Z = USB

B2

B

Per-unit:

z = r + j x⋅ ⇔ Z

Z = R

Z+ j X

ZB B B⋅

Transient Stability


Referenced exciter voltages The voltages of the synchronous-machine models are referenced variables with the reference network voltage UB of the machine terminal's node as the reference variable. In order to simulate exciter devices, the exciter voltage and the input variables of the voltage controller model must be converted from network-per-unit into exciter-per-unit. In accordance with IEEE [4], the reference variable UE for exciter voltages is that exciter voltage which in no-load mode produces rated voltage at the machine ter-minals on the synchronous machine. Network-per-unit and exciter-per-unit are different only if the saturation of the syn-chronous machine is simulated or if the synchronous machine's rated voltage UN is not equal to the reference voltage UB. Network-per-unit: Conversion factor:

ufB ( )UU

UA e

B

E

BB

= UN ⋅ + ⋅ ⋅1 0 2,

A,B ... saturation factors (see synchronous machines) Exciter-per-unit:

ufE ⇔ ( )uU

A efE

BB

= uU

fBN

⋅⋅ + ⋅ ⋅1 0 2,

Transient Stability


Network Elements

Controlled Admittance Controlled admittances are the most general form of a simulation model in the Transient Stability module. Controlled admittances in combination with controller models of any desired structure give users complete freedom to choose the na-ture and complexity of the mathematical model to be simulated. Basically, a controlled admittance is a constant admittance ycad, which has been permanently incorporated in the network admittance matrix. The constant admit-tance's value is entered through Dynamic Data file, and is independent of the value of the admittance in the initial load flow. The effective admittance is gener-ated by an injected current into the admittance matrix. The effective admittance (in [Ohm-1]) can be controlled by any desired controller model. Active and reactive components of the admittance can be controlled inde-pendently of each other. A controlled admittance is primarily intended for modeling static reactive power compensators. In these cases, it is only the reactive component that is controlled, the active component (if it does not equal 0) remains unchanged. The controlled admittance corresponds to the "Interface" block of Fig. 11.67 in [7]. However, controlled admittances can also be used to model (above and beyond static compensators) dynamic load models, special synchronous-machine models and the like. The use of controlled admittances requires a good knowledge of the effect of the admittance concerned and of the supply current on the solution of the network equations. Since plausibility checks are not run, divergence or numerical instabil-ity can easily be achieved! Block diagram of the simulation model

SB

UB2

SB

UB2 j

G

By

ycad

ik

ycad

uk

uk

Π

Iterations

icad

Transient Stability


Variables All variables of a controlled admittance are analog variables. A… Voltage magnitude [pu] B… Voltage angle [degree] C… Current magnitude [A] D… Current angle [degree] E… Active power [MW] F… Reactive power [MVAr] G… Magnitude of the effective admittance [Ohm-1] H… Angle of the effective admittance [degree] I… Active component of the effective admittance [Ohm-1] J… Reactive component of the effective admittance [Ohm-1] Switching operations none Function Generators A function generator is a fictitious network element, serving to test control equip-ment or as a disturbance function for network simulation. A function generator is switched on and off by means of a switching operation. More than one function generator can be switched on simultaneously. The following types of function generators are avail-able:

A .... Step

If the generator is switched off, the output sig-nal is 0. If the generator is switched on at the time t0, the output signal equals the constant value K.

B .... Ramp

If the generator is switched off, the output sig-nal is 0. If the generator is switched on at the time t0, the output signal is computed, using the func-tion

.

Transient Stability


( )y = Min K , KT

⋅ −

t t 0

If |T| < 0.0001, the ramp function corresponds to a jump function of the size K.

C .... Sine If the generator is switched off, the output signal is 0. If the generator is switched on at the time t0, the output signal is computed, using the function

( )y = K sin 2T

⋅ ⋅ − +

πϕt t T0 .

If |T| < 0.0001, the sine function corresponds to a jump function of the size K.

Variables

A .... Output of the function generator [pu]

Switching operations

A .... Generator ON Parameters: none The function generator is switched on.

B .... Generator OFF Parameters: none The function generator is switched off.

Simulation The simulation sequence can be controlled in dependence on the computed re-sults using a fictitious network element called "Simulation". Variables None Switching operations A Abort simulation Parameter: none

Transient Stability


The switching operation aborts the simulation immediately. B Set debug flag Parameter: P1 Number of debug flag[#] Debug flag Number P1 is set, and the debug information concerned is output. The debug flag remains set until it is reset again. If the debug flag had not been set, the switching operation has no function. C Reset debug flag Parameter: P1 Number of debug flag [#] Debug flag Number P1 is reset. If the debug flag had not been set, the switching operation has no function.

Maximum-minimum relays Maximum-minimum relays monitor a measured variable for over or under violation of a preset measured value. If the measured variable of a maximum relay ex-ceeds the threshold value (Starting), a time counter is started, which defines a time interval. If the measured variable concerned remains above the threshold value during this time interval, then a trip command will be output at the end of the interval. If the measured variable falls back below the threshold value, the time counter will be reset, and no trip command will be output. If a trip command is given, the associated trip function will be executed on expiry of a breaker opening time. Examples of maximum-minimum relays are - overcurrent relays - overvoltage relays - undervoltage relays - power relays - impedance relays (central impedance circuit) - frequency relays The concept of a monitored measured variable is not restricted to the measured variables listed above. Any variable can be used as monitored measured variable. Up to four relay stages can be operated by one measured variable. Any desired switching operation can be triggered as a trip function assigned to a relay stage. More than one trip function can be assigned to one relay stage. Start-ing or trip signals can be utilized as signal connections for other relays. The monitoring of specific variables can advantageously be utilized for controlling the simulation run. To determine the stability limits, for example, the rotor angle

Transient Stability


can be monitored. If a defined value is exceeded, then the simulation will be aborted as the "switching operation" of the relay. The generator will then already have fallen out of synchronism, and the computation can be aborted. Variables All variables of max/min relays are binary variables. A Trip, Stage 1 B Trip, Stage 2 C Trip, Stage 3 D Trip, Stage 4 Switching operations None

Distance protection The simulation model for distance protection equipment processes analog and bi-nary input signals, and sends out binary output signals. The signal flow plan is shown on Page 15.

r

x

The analog input signals are current and voltage of the branch element as-signed. Additionally, and independent of all subsequent functions, the current is monitored for over violation of a minimum value and the voltage for under violation of a maximum value. If there is no over or under violation, none of the subsequent time counters will be started. In the "direction" block, the direction of the fault is determined from current and voltage. If the measured impedance in the r/x diagram is in the hatched area (see picture on right), then the decision will be for forward direction. Otherwise, it is a case of backward direction. The effect of the direction can be set as positive, negative or inoperative both for starting and for the measuring stages. This means

Transient Stability


characteristics can be simulated as forward-directional, backward-directional or non-directional. In the "Starting" and "Measurement" blocks, tripping of the distance relay or the start of a time counter for a measuring stage is derived by means of impedance characteristics, which can be used for the following functions: - Starting - Stage 1 - Stage 1 extended - Stage 2 - Stage 3 - Trip and triggering of an external auto-reclosure Each of these functions can be associated with the following impedance charac-teristics. More than one characteristic of the same type or different types can be associated with one function. Overcurrent starting The use of overcurrent starting is predominantly intended for the "Starting" func-tion. The overcurrent starting function evaluates only the current of the branch element, and is voltage-independent. It is thus an "impedance characteristic" only in a very general sense. If the current of the branch element exceeds the minimum-current value, the time counter of the function assigned will be started. Circular characteristic The circular characteristic in the r/x diagram is shown in the adjacent picture. If the impedance point measured is located inside the circle, then the associated time counter will be started. The circle has a diameter of Z, and is offset from the coordinate center by (R,X). Polygonal characteristic The polygonal characteristic in the r/x diagram is shown in the adjacent picture. If the impedance point measured is located inside the polygon, then the associated time counter will be started. The polygon is defined by four corner points. If the fourth corner point is not specified, the poly-

r

x

XR

Z

r

x

(R1,X1)(R4,X4)

(R2,X2)(R3,X3)

Transient Stability


gon will be interpreted as a triangle. Polygons with more than 4 corner points can be created by combining several 4-cornered polygons. Binary signals Binary signals can be used to influence the behavior of the distance protection model by external events. The binary input signals can be binary output signals from other distance relays or from other types of relays as well. These signals can be altered both at the signal source and at the input of the distance relay. For controlling the time dependent signal flow, binary signals can be provided at the source with a pick-up delay TAS and/or with a drop-out delay TAF. For the time of signal transmission between the signal source and the destination, the signal can be assigned a transmission time TL.

TAS

TAF

TL

Signal source

Pick-up delay

Drop-out delay

Transmission time The illustration above shows the basic manner in which the signal is influenced. When the signal arrives at the distance relay, it can be altered as follows: 0 Signal is not altered 1 Signal is inverted 2 Signal is always 1 3 Signal is always 0 Note that a binary signal can have the following functions in the distance protec-tion model (see illustration at the end of this chapter): Blocking A trip command to the circuit-breaker will be given only when this signal is not be-ing received. Enable The time counter of Stage 1 will not be started until the external signal is being re-ceived. The start of Stage 1 time counter will, however, be blocked only until the time, TFG, has elapsed. On expiry of

Transient Stability


TFG, Stage 1 time counter will be started even if no enable signal is being re-ceived. Intertripping If a signal is being received, a trip command will be sent provided that the direc-tional starting has been activated. Range extension When an external signal is being received, the Stage 1 extended is activated. External starting Starting function begins when an external signal is being received. Auto-reclosure blocking The time counter for a trip using the characteristic for auto-reclosure will be started only when no external signal is being received. Variables All variables of the distance relay are binary variables. B General starting C Directional starting D General tripping E Tripping, Stage 1 F Tripping, Stage 1 extended G Tripping, Stage 2 H Tripping, Stage 3 I Tripping, directional starting J Tripping, non-directional starting K OFF command (signal to circuit breaker) L Forward direction M Auto-reclosure Switching operations None

Transient Stability


Signal flow plan for distance protection

&

&

&

&

&

&

&

&

&

≥1

&

&

&

&

&

Range extension

Enable

Intertripping

Blocking

Auto-reclosure blocking

Current

Voltage

External starting

Starting

Messung

1

3

2

1E

WE

TAU

I> & U<

Internal Signals:

Circuit-breakeropened

1

Direction

1

≥1

≥1≥1

TAG

T3

T2

T1E

T1

TWE

TFG

TLS

4 .....Tripping Stage 1

2 .....Directional starting1 .....General starting

5 .....Tripping Stage 1 extended6 .....Tripping Stage 27 .....Tripping Stage 38 .....Tripping directional starting9 .....Tripping non-directional starting

3 .....General tripping

10 ....OFF command11 ....Forward direction12 ....Auto-reclosure

1

2

9

8

7

6

5

4

12

11

10

3

Pole slip protection Pole slip is a dynamic, asynchronous operation of two or more synchronous gen-erators, in which the air-gap voltages of the generators run at least once through phase opposition.

Transient Stability


ZA

ZB

ZC

r

x

α ϕ

In the event of a short-circuit in the network, a generator is relieved of active power and accelerated, because the turbine torque does not change immediately. If the short-circuit is of short duration, the generator will indeed exhibit power swing in relation to the network, but the oscillation will decay under damping. If the short-circuit duration exceeds a certain value, which will depend on generator ca-pacity utilization, the type of fault concerned, and how far away it is, the generator will pull out of synchronism, exhibiting slip against the network. Pulling out of syn-chronism is accompanied by major oscillations in current and power, and consti-tutes a severe stress case for the generator involved. In order to avoid mechanical and thermal damage, a slip must be detected as soon as possible, and the gen-erator disconnected from the network. In a network with more than one generator, the slip can be acquired using the movement of the impedance pointer, viewed from the generator terminals, in the r/x plane. The characteristic of the pole slip current in the Transient Stability module con-sists of a lens-shaped area divided into two lens halves by a straight line in the lens axis. A straight line which is aligned perpendicular to the lens axis will divide the r/x plane into areas close to and remote from the generator terminals. The co-ordinate center designates the generator terminals. The position of the lens is de-fined by the angle phi of the lens axis, and the shape of the lens by the angle al-pha. The criterion for a slip is the movement of the impedance pointer through the lens. The impedance pointer must enter into the lens area on one side, and exit from the lens again on the other side. The impedance pointer must dwell for at least 25 ms in each half of the lens. If the impedance pointer passes through the lens above the straight line, this means the slip concerned is remote from the genera-tor terminals, and in Stage 2, otherwise it is close to the generator terminals, and in Stage 1. The maximum acquirable slip frequency is specified by selecting the lens size and the lens shape. The wider the lens is, the higher the slip frequencies are which can be detected. The width of the lens, together with the lens size, also deter-mines the range in the r-direction, which must exhibit a sufficiently large distance from the minimum operating impedance.

Transient Stability


The relay's trip function can be specified separately for Stage 1 and Stage 2. More than one trip function can be defined for each level. Any switching operation can be assigned as the trip function. For a description of the trip functions, see under "Maximum-minimum relays". Variables All variables of the pole slip relay are binary variables. A Trip, Stage 1 B Trip, Stage 2 Switching operations None

Overcurrent protection Functional description In electricity networks, an overcurrent protection feature monitors a measured cur-rent, and sends a trip command to a circuit-breaker when the current meets de-fined starting and trip conditions. Simulation of an overcurrent protection feature in the Transient Stability module is accordingly divided up into • measured variable • starting condition • trip condition • trip function An overcurrent protection feature possesses a measured variable, a starting con-dition and a trip function. An overcurrent protection feature can, however, have more than one trip condition (e.g. independently time-delayed high-current level, dependently time-delayed overcurrent level). Measured variable The measured variable can be a current magnitude from any network element. Other variables are not permissible (error message). Starting condition The starting condition is the over violation of a starting current IA, which is the mul-tiple KA of the set current IE. After starting, the trip time begins to run (trip condi-

Transient Stability


tion). If the current drops below a reset current IR (which is the multiple KR of the set current IE), before the trip time has elapsed, the trip time will be reset and no trip will be executed.

ERR

EAA

IKIIKI

⋅=⋅=

Trip condition Different characteristics can be selected for the trip time, as the trip condition. An overcurrent protection feature can be associated with more than one trip charac-teristic. 1) Independent trip time The trip time tA is constant, and independent of the current measured:

EA Tt =

2) Analytically dependent trip time The trip time tA is variable, and depends non-linearly on the measured current I. The non-linear correlation is analytically given as,

1II

KTt

2K

E

1

E

A

−

=

By means of K1 and K2, the trip characteristics can, for example, be formed in ac-cordance with IEC 255: Normally dependent (Type A) : K1 = 0.14 K2 = 0.02 Heavily dependent (Type B) : K1 = 13,5 K2 = 1 Extremely dependent (Type C) : K1 = 80 K2 = 2 If the current is more than the multiple KB of the set current IE, the trip time will not be reduced any

further; ( BE

KIImax =

). KB is, for example, equal to 20.

Transient Stability


3) Tabularly dependent trip time The trip time tA is variable, and is non-linearly dependent on the current I. The non-linear correlation is given as a tabular function:

=

EII

E

A fTt

A tabular function can, for example, be used to simulate fuse characteristics. Trip function If the measured current remains above the reset current IR longer than the trip time after the starting current IA has been exceeded, the trip function will be initi-ated. In the Transient Stability module, the trip function is any desired switching operation. More than one switching operation, can also be assigned to a single trip function. On expiry of a breaker opening time which can be set for each switching opera-tion, the switching operations will be executed. Variables The variables of an overcurrent relay are analog or binary variables. A Measured current I [A] B Effective trip time tA [s] C Starting condition fulfilled [binary] D Trip condition fulfilled [binary] Switching operations No switching operations can be performed at an overcurrent protection feature. This must NOT be confused with switching operations which are caused by an overcurrent protection feature. Pickup Conditions Subroutine REGS gives as currents the square of per unit currents:

2

B

2IIi

= IB current base of network element

B

B

U3S⋅

Pickup condition in nominal values is

( )2EA2B

22A

2A IKIiIIII ⋅>⋅⇒>⇒>

Results as programmed pickup condition:

Transient Stability


pckaiI

IKi 22

B

EA2 >⇒

⋅>

where

2

B

BEA2

B

EAS

UIK3I

IKpcka

⋅⋅⋅=

⋅=

Analytical Dependent Time Delay Characteristics Subroutine REGS gives as currents the square of per-unit currents (see above). The characteristic requires

21

2

E

B2

E

B

E IIi

IIi

II

⋅=⋅=

The analytical characteristic results as

( ) 1pciei

1tck

1IIi

KTt

2tck22

K2

E

B2

1

E

A2 −⋅

=

−

⋅

=

where

2

BE

B2

E

BUI

S31

IIpcie

⋅

⋅=

=

1K1tck =

2K2tck 2=

Transient Stability


Program control

Simulation run and table output Initial integration step length The simulation is started with the initial step length, and altered automatically by the program. If the step length control has been switched off, then the entire simu-lation will be executed with the integration step length, XDT0. Default value: 0.001 s (when XDT0 < 0.0001 s) Simulation duration Default value: XDT0 (when TEND < XTD0) Automatic step length control 0 switched off 1 switched on Default value: 1 (when NVIS ≠ 0) Name of a synchronous machine for reference rotor angle The rotor angle of the synchronous machine with this name is the reference vari-able for outputting the rotor angles of all other synchronous machines. All rotor angles are output as the difference from the rotor angle of the reference synchro-nous machine. Controlling program run stop 0 No stop 1 Stop after reading in load flow 2 Stop after reading in and initializing the dynamic data 3 Stop after reading in and initializing the protective data 4 Stop after reading in all data Default value: 0 (when NST < 0 or > 4) Control of list outputs of variables 0 Lists are not printed 1 Lists are printed Default value: 1 (when KLIS ≠ 0)

Transient Stability


Control of output of variables on file 0 Variables are not output 1 Variables are output Default value: 1 (when KMON ≠ 0) Number of points per variable on file It states only the approximate number of points per variable. Due to switching op-erations and step length control, the actual number may deviate from that speci-fied. Default value: 150 (when NVF < 1)

Simulation parameters Number of sub-intervals for control circuits The system equations for the control circuits are solved NSI times within one inte-gration step. Minimum value is 2. Default value: 5 (when NSI < 2 or > 100) Maximum number of iterations for the implicit solution Default value: 100 (when NITAMX < 1 or > 1000) Convergence tolerance for active power of synchronous machines Default value: 0.001 per unit (when EPSP < 10-8 or > 0.1) Convergence tolerance for real and imaginary components of node voltages Default value: 0.001 per unit (when EPSV < 10-8 or > 0.1) Limitation of the table for multiplication of the initial step length The integration step length is altered in multiples of the initial step length. Multipli-cation proceeds in accordance with the table given below. The maximum step length can be specified by limiting the table. 1 1 5 15 9 35 13 55 17 75 2 2 6 20 10 40 14 60 18 80 3 5 7 25 11 45 15 65 19 85 4 10 8 30 12 50 16 70 20 90 Default value: 20 (when NVIMMX < 1 or > 20) Maximum number of iterations for the implicit solution after which the step length to be reduced

Transient Stability


Default value: 7 (when NVIIMX < 1 or > 20) Number of steps to further increase the step length after the last increase of the step length Default value: 3 (when NVIINC < 1 or > 20) Number of steps to increase the step length after the last decrease of the step length Default value: 10 (when NVIDEC < 1 or > 20) Maximum active-power mismatch to increase the step length Default value: 0.001 per unit (when DEPEMX <10-6 or >0.1) Maximum frequency mismatch to increase the step length Default value: 0.001 rad/s (when DERSMX < 10-6 or > 0.1)

Symbol Library


Symbol Library

Overview

With the NEPLAN Symbol Library you can • modify the existing element and protection device symbols, • add new element and protection device symbols, using existing symbols as a

template, • draw your own graphic symbols.

Basic Concepts

The symbols can be categorized to the following groups: 1. Symbols of network elements with one or more connecting points to nodes

(loads, transformers, etc.), 2. Symbols of protection devices and switches (relays, earthing switches, etc.) 3. Symbols for "General Elements" 4. Disconnection Symbol and Flow Indicator 5. Drawing Symbols

In the main application you can select the network and the protection device sym-bols with "Input - Symbol Selection". To draw a "drawing symbol" you have to select "Draw - Symbol...". Select the symbols for the disconnection symbol and flow indicator with "Options - Symbols".

Symbols of Network Elements Symbols of network elements are drawn between their connecting points (Fig. 17.1). To each graphic object of the symbol, you can assign a connection side. This side will be considered, if you color the network according to the voltage levels. For switchable symbols you get two diagrams, one for the "ON" state and the other for the "OFF" state.

Symbol Library


Connecting Point

Fig. 17.1 Symbols of network elements

Symbols of Protection Devices and Switches Protection devices are positioned at the logical switches of an element and are connected to the corresponding node. The connecting point of a protection device determines the distance from the node (Fig. 17.2).

Fig. 17.2 Protection Devices and Switches

Symbols for "General Elements" The general element type, can be used for documentation and information pur-poses. These elements will not be used for the calculation. New general element types can be defined with the Symbol Library. For each element type it is possible to assign a SQL database table (requires the optional SQL database driver module). The fields of this SQL table can be defined by the user.

Disconnection Symbol and Flow Indicator You can define your own symbols for the disconnection symbol and flow indicator. The connecting point of the disconnection symbol determines the distance from

Symbol Library


the node. The disconnection symbol will be shown, if the display of the "logical switches" is not selected (see "Drawing parameters").

Drawing Symbols The drawing symbols are not connected to any other element. They can be scaled in the main application.

Mouse Buttons

Select Mode Pressing the left mouse button selects and deselects the graphic objects. Holding down the "Shift-key" allows multiple selection. Press the left mouse button while moving the mouse to move selected objects.

Drawing Mode To enter new objects press the left mouse button while moving the mouse.

Double-Click A double-click on an objects brings up the property dialog box.

Symbol Library


Graphical Elements

Line Width (Symbol Library) The line widths of the different symbols are considered as follows:

Network elements, Protection Devices

If the line width is set to 0.0 mm, the setting for the corresponding element of the main application are taken into consideration for the line width. Line widths > 0.0 mm will be taken into consideration by the main application.

"General Element", Disconnection symbol, Flow indicator, Drawing symbols

If the line width is set to 0.0 mm, the main application sets the line width to 1 pixel (∼ 0.25 mm). Line widths > 0.0 mm will be taken into consideration by the main application.

Symbol Library


References


References

Additional References

/ 1 / L. Busarello Über die Entwicklung eines Programmsystems zur Analyse und Planung elektrischer Energieversorgungsnetze für Arbeitsplatzcomputer Dissertation Nr. 8319, Eidgenössische Technische Hochschule Zürich, 1987

/ 2 / VDE0102 Teil 100 Berechnung von Kurzschlussströmen in Drehstromnetzen Entwurf April 1985, VDE-Verlag, D-Berlin 12

/ 3 / H. Happolt, D. Oeding Elektrische Kraftwerke und Netze Springer-Verlag

/ 4 / O. I. Elgerd Electric Energy System Theory. An Introduction McGraw-Hill, 1971

/ 5 / Elektrische Energietechnik, Bände 1-3 Springer-Verlag, 29. Auflage, 1988

/ 6 / L. Busarello, G. Balzer, K. Reichert Die Kurzschlussstromberechnung nach IEC 909 SEV-Bulletin, Heft 9, 1989

/ 7 / Xiao-Ping Zhang Fast three phase load flow method IEEE Transaction on Power Systems, Vol. 11, No. 3. August 1996

/ 8 / Funk, Hantel Frequenzabhängigkeit der Betriebsmittel von Drehstromnetzen ETZ-Archiv Band 9 (1987), Heft 11, Seiten 349-356

/ 9 / W. Tenschert Simulation elektromechanischer Ausgleichsvorgänge in elektrischen Energienetzen mit Nachbildung von Schutzeinrichtungen. Dissertation Technische Universität Wien, 1988

References


/ 10 / I.M. Canay Determination of model parameters of synchronous machines. IEE Proc., Vol.130, Pt.B., 1983, H.2, S.86-94

/ 11 / Polschlupfschutz GZX 104 - Technische Beschreibung. BBC, CH-ES 31-58 D

/ 12 / Excitation System Models for power system stability studies. IEEE Committee Report IEEE Transactions, Vol. PAS-100, 1981, S.494-509

/ 13 / P.M. Anderson, A.A. Fouad Power System Control and Stability The Iowa State University Press, 1977

/ 14 / S. Ertem, Y. Baghzouz Simulation of Induction Machinery for Power System Studies IEEE Transactions on Energy Conversion, Vol.4, 1989, S.88-94

/ 15 / P. Kundur Power System Stability and Control EPRI Power System Engineering Series McGraw-Hill, Inc.

/ 16 / G. Hosemann (Hrsg.) Hütte - Taschenbücher der Technik; Band3: Netze Springer Verlag, Berlin, 1987 ISBN 3-540-15359-4

/ 17 / H.-J. Haubrich (Hrsg.) Zuverlässigkeitsberechnung von Verteilungsnetzen. 1. Auflage, Aachen, Verlag der Augustinus-Buchhandlung1996 (Aachener Beiträge zur Energieversorgung, Bd. 36) ISBN 3-86073-492-X

Appendix


Appendix

The Structure of the Import-/Export-Files

EDT-File With the help of the EDT-file, topological and electrical data can be imported and exported. This File can be generated and read by MS-Excel (see "Interfaces to NEPLAN - Import/Export" in chapter "Tutorial" and "File - Import/Export" in chapter "Menu Options"). When exporting the file, the user will be asked about the field seperator to use in the EDT-file. The structure and the description of the file are found below:

Appendix


----------------------------------------------------------------------------

| Data field| Elements |

|--------------------------------------------------------------------------|

|Name |Type | Line |Coupling|Reactor |2-w.Tran|3-w.Tran|Shunt |Net.feed|

|--------------------------------------------------------------------------|

| id | N2 | [1] | [2] | [3] | [4] | [5] | [50] | [51] |

| l1 | L |Switch 1|Switch 1|Switch 1|Switch 1|Switch 1|Switch 1|Switch 1|

| l2 | L |Switch 2| |Switch 2|Switch 2|Switch 2| regul ?| |

| l3 | L | | | |regulate|Switch 3| | |

| l4 | L |Cable ? | | |Unit Tr.| | | |

| c1 | C8 |No.nam 1|No.nam 1|No.nam 1|No.nam 1|No.nam 1|No.nam 1|No.nam 1|

| c2 | C8 |No.nam 2|No.nam 2|No.nam 2|No.nam 2|No.nam 2| | |

| c3 | C8 | | | | |No.nam 3| | |

| c4 | C8 |Elem.nam|Elem.nam|Elem.nam|Elem.nam|Elem.nam|Elem.nam|Elem.nam|

| c5 | C10 | | | |Vectorgr|Vectorgr| | |

| c6 | C24 | Type | | | Type | | | |

| c7 | C8 |Freq.dep| |Freq.dep|Freq.dep|Freq.dep|Freq.dep|Freq.dep|

| r1 | N8 | Un | Un | Un | Un1 | Un1 | Un | Un |

| r2 | N8 | B1(1) | | | Un2 | Un2 | | |

| r3 | N8 | B1(0) | | | Delta U| Un3 | | |

| r4 | N8 | G1(1) | | Ur | Ur1 | Ur1 | | |

| r5 | N8 | G1(0) | | | Ur2 | Ur2 | | |

| r6 | N8 | | | | Beta | Ur3 | | |

| r7 | N8 | Ir max | | | Sr | Sr12 | P(1) | Sk"max |

| r8 | N8 | X(1) | X(1) | ukr(1) | ukr(1) |ukr(1)12| | Sk"min |

| r9 | N8 | X(0) | X(0) | | ukr(0) |ukr(1)23| | |

| r10 | N8 |Per.temp| | |reg.side|ukr(1)13| | |

| r11 | N8 | R(1) | R(1) | uRr(1) | uRr(1) |uRr(1)12| | |

| r12 | N8 | R(0) | R(0) | | uRr(0) |uRr(1)23| | |

| r13 | N8 | Y(0) | Y(0) | | Tap act|uRr(1)13| | |

| r14 | N8 | Y(1) | Y(1) | | XE1 | XE1 | | |

| r15 | N8 | Number | Ir | | XE2 | XE2 | | |

| r16 | N8 | ir min | Ipmax | | RE1 | RE1 | | Ik"max |

| r17 | N8 | red.fac| | | RE2 | RE2 | | Ik"min |

| r18 | N8 | C(1) | | Ir | I0 |ukr(0)12| P(0) | R1/X1 |

| r19 | N8 | C(0) | | | Tap min|ukr(0)23| Q(1) | Z0/Z1 |

| r20 | N8 | Length | | | Tap max|ukr(0)13| Q(0) | C |

| r21 | N8 | B2(1) | | | P Fe | Sr23 | Umin | |

| r22 | N8 | B2(0) | | | Tap mit| Sr13 | Umax | |

| r23 | N8 | Q | | | Preg | RE3 | Qmin | |

| r24 | N8 | Units | | | | XE3 | Qmax | |

| r25 | N8 | G2(1) | | | |reg.side| Imax | |

| r26 | N8 | G2(0) | | | | Delta U| | |

| r27 | N8 | | | | |Tap min | | |

| r28 | N8 | | | | |Tap max | | |

| r29 | N8 | Ltg_sec| | | |Tap mit | | |

| r30 | N8 | Num_sec| | | |Tap akt | | |

| c8 | C31 |Descr.N1|Descr.N1|Descr.N1|Descr.N1|Descr.N1|Descr.N1|Descr.N1|

| c9 | C31 |Descr.N2|Descr.N2|Descr.N2|Descr.N2|Descr.N2| | |

| c10 | C31 | | | | |Descr.N3| | |

| c11 | C31 |Descr.El|Descr.El|Descr.El|Descr.El|Descr.El|Descr.El|Descr.El|

----------------------------------------------------------------------------

Appendix


Table (continue): ----------------------------------------------------------------------------


|--------------------------------------------------------------------------|

|Name |Type |Synchron|Asynchro|PS-Unit | Series |Filter |Parallel| Series |

|--------------------------------------------------------------------------|

| id | N2 | [52] | [53] | [54] | [6] | [55] | [7] | [56] |

| l1 | L |Switch 1|Switch 1|Switch 1|Switch 1|Switch 1|Switch 1|Switch 1|

| l2 | L |Unit Gen|Conv dri|Turbo ? |Switch 2| |Switch 2| |

| l3 | L | | | | | | | |

| l4 | L | | | | | | | |

| c1 | C8 |No.nam 1|No.nam 1|No.nam 1|No.nam 1|No.nam 1|No.nam 1|No.nam 1|

| c2 | C8 |Turbo |Ml(s) | |No.nam 2| |No.nam 2| |

| c3 | C8 | |Me(s) | | | | | |

| c4 | C8 |Elem.nam|Elem.nam|Elem.nam|Elem.nam|Elem.nam|Elem.nam|Elem.nam|

| c5 | C10 | |I(s) |Vectorgr| | | | |

| c6 | C24 | Type | Type | | | | | |

| c7 | C8 |Freq.dep|Freq.dep|Freq.dep|Freq.dep|Freq.dep|Freq.dep|Freq.dep|

| r1 | N8 | Un | Un | Un1 | Un | Un | Un | Un |

| r2 | N8 | |Start.de| Un2 | | | | |

| r3 | N8 | |P oper. | xd" | | | | |

| r4 | N8 | Ur | Ur | Ur1 | Ur | Ur | Ur | Ur |

| r5 | N8 |Ufmx/Ufr| Mk/Mr | Ur2 | | | | |

| r6 | N8 | | M0 | x(2) | | | | |

| r7 | N8 | Sr | Pr | SrT | | Qr | Sr | |

| r8 | N8 | mue | Number | ukr(1) | L1 | L1 | L1 | L1 |

| r9 | N8 | RE | Ir | ukr(0) | | | | |

| r10 | N8 | XE | M1 | xdsat. | | | p | |

| r11 | N8 | | M2 | uRr(1) | R1 | R1 | R1 | R1 |

| r12 | N8 | |Q oper. | uRr(0) | | | | |

| r13 | N8 | | |Cos(phi)| | | | |

| r14 | N8 | X(0) | J | XE1 | | | | |

| r15 | N8 | RG | sr | RE1 | | f0 | f0 | |

| r16 | N8 | Ikk | ETA | | | G | G | |

| r17 | N8 |cos(phi)|Polepair| | | | | |

| r18 | N8 | xd" |Cos(Phi)| SrG | C1 | C1 | C1 | C1 |

| r19 | N8 | x(2) | Ia/Ir |Ufmx/Ufr| | | | |

| r20 | N8 | xdges. | Ma/Mr | | | | | |

| r21 | N8 | Pmin |t switch| | | | | |

| r22 | N8 | Pmax |cos sta.| | | | | |

| r23 | N8 | Qmin | RM | | | | | |

| r24 | N8 | Qmax | | | | | | |

| r25 | N8 | | | | | | | |

| r26 | N8 | | | | | | | |

| r27 | N8 | | | | | | | |

| r28 | N8 | | | | | | | |

| r29 | N8 | | | | | | | |

| r30 | N8 | | | | | | | |

| c8 | C31 |Descr.N1|Descr.N1|Descr.N1|Descr.N1|Descr.N1|Descr.N1|Descr.N1|

| c9 | C31 | | | |Descr.N2| |Descr.N2| |

| c10 | C31 | | | | | | | |

| c11 | C31 |Descr.El|Descr.El|Descr.El|Descr.El|Descr.El|Descr.El|Descr.El|

----------------------------------------------------------------------------

Appendix


Table (continue): -------------------------------


|-----------------------------|

|Name |Type |Serie Eq|Shunt Eq|

|-----------------------------|

| id | N2 | [11] | [12] |

| l1 | L |Switch 1|Switch 1|

| l2 | L | | |

| l3 | L |Eq.Type |Eq.Type | Eq.Type: 1: Loadflow 2: Short circuit

| l4 | L | | |

| c1 | C8 |No.nam 1|No.nam 1|

| c2 | C8 |No.nam 2| |

| c3 | C8 | | |

| c4 | C8 |Elem.nam|Elem.nam|

| c5 | C10 | | |

| c6 | C24 | | |

| c7 | C8 | | |

| r1 | N8 | Un1 | Un |

| r2 | N8 | Un2 | |

| r3 | N8 | | |

| r4 | N8 | | |

| r5 | N8 | | |

| r6 | N8 | | |

| r7 | N8 | R12(1) | R(1) |

| r8 | N8 | X12(1) | X(1) |

| r9 | N8 | R21(1) | R(2) |

| r10 | N8 | X21(1) | X(2) |

| r11 | N8 | R12(2) | R(0) |

| r12 | N8 | X12(2) | X(0) |

| r13 | N8 | R21(2) | P gen |

| r14 | N8 | X21(2) | Q gen |

| r15 | N8 | R12(0) | P loa |

| r16 | N8 | X12(0) | Q loa |

| r17 | N8 | R21(0) | |

| r18 | N8 | X21(0) | |

| r19 | N8 | | |

| r20 | N8 | | |

| r21 | N8 | | |

| r22 | N8 | | |

| r23 | N8 | | |

| r24 | N8 | | |

| r25 | N8 | | |

| r26 | N8 | | |

| r27 | N8 | | |

| r28 | N8 | | |

| r29 | N8 | | |

| r30 | N8 | | |

| c8 | C31 |Descr.N1|Descr.N1|

| c9 | C31 |Descr.N2| |

| c10 | C31 | | |

| c11 | C31 |Descr.El|Descr.El|

-------------------------------

Appendix


As seen above a record consists of 42 data fields. Each data field is described by its name and its type. The following types exist:

N2: Numerical field (integer value) L: Logical field (T=True, F=False) C8: Character field C10: Character field C24: Character field C31: Character field N8: Numerical field (float value)

The first data field "id" gives the type of element. For example with [1] a line will be described. The file is an ASCII-file. The description of the data fields are given in chapter "Element Data Input and Models". The logical switches are saved in L1, L2 and if necessary in L3:

L: "T" merans: Switch closed (element connected at node 1, 2 or 3) L: "F" means: Switch open

The load and disconnect switches are also exported/imported. Their identifica-tions are:

• id = 8: disconnect switch (node-node) • id = 9: load switch (node-node) • id = 10: circuit breaker (node-node)

For these elements the logical switches "L3" and "L4" indicate, if the node 1 (starting node) or/and node 2 (ending node) should be reduced during the calcu-lation. "T" means reduce, "F" means not reduce (see "Disconnect Switch" in chapter "Element Data Input and Models"). The data fields are the same as for couplings. The units information for exporting/importing the lines are:

• units = 1: Line parameters in OHM/km, µF/km, µS/km and the length in km • units = 2: Line parameters in OHM/miles, µF/miles, µS/miles and the length

in miles • units = 3: Line parameters in OHM/1000feet, µF/1000feet, µS/1000feet and

the length in 1000feet

Appendix


The data of network equivalents are only exported, if the module network reduc-tion is available.

Line Sections: Line sections are also included in the EDT-file. The data field "Ltg_sec" gives the information if the record is for a line or a line section:

• 0: normal line • 1: line section.

For a line consisting of several sections the data field "Num_sec" must contain the number of sections. For example, if a line consists of 3 sections the data field "Num_sec" must contain the number 3. The following data fields are not important for line sections: "l1" to "l3" and "c1" to "c5" and "c7" as well as "r1", "r21" and "r22". The program will calculate the total length and the parameters of the lines, which consist of several sections, when reading the EDT-file (import).

Appendix


NDT-File In the NDT-file the node data (load data) are imported or exported. The File can be generated and read by MS-Excel. When exporting the file, the user will be asked about the field seperator to use in the EDT-file. The structure and the description of the record fields are:

------------------------

| Data field| |

------------------------

|Name |Type | Node |

------------------------

| c1 | C8 |Node name |

| c2 | C2 | LF-Type |

| p | L | HV/LV |

| r1 | N8 | Poper inp|

| r2 | N8 | Qoper inp|

| r3 | N8 | Umin |

| r4 | N8 | Umax |

| r5 | N8 | U |

| r6 | N8 | WU |

| c3 | N8 | El.Name |

| r8 | N8 | Si.factor|

| r9 | N8 | Poper cal|

| r10 | N8 | Qoper cal|

| c4 | C24 | Type |

| p2 | L | Lineload |

| r11 | N8 | Distance |

| r12 | N8 | DU |

| r13 | N8 | xp |

| r14 | N8 | xq |

| r15 | N8 | P0 |

| r16 | N8 | Q0 |

| r17 | N8 | Ureg | Regulated or nominal node voltage

| r18 | L | Switch | Indicates, if the Load is connected (T) or not (F)

| c5 | C31 | Descr.El.|

| r19 | L | No.Info | Indicates, if only the nominal node voltage (T) is

------------------------ read in

Appendix


The same is valid as in the ELD file. The fields c1 and c3 can be 8 or 17 charac-ters long. The field p indicates, if the numerical values are given for low (kVA, A, V) or high (MVA, kA, kV) voltage:

• p1: "T" means: Input for high voltage. • p1: "F" means: Input for low voltage.

The field c2 "LF-Type" gives the node type:

Type: "SL" means slack node Type: "PQ" means PQ node Type: "PV" means PQ node more types: "PI", "IC", "PC", "SC".

The load type is saved in the field "Type". "Line load" indicates, whether it is a line load or not:

• p2: "T" means: line load. • p2: "F" means: load/generator/feeder/motor.

The distance of the line load in meter from the line starting node is saved into "Distance". The number of domestic units for the loads and line loads are saved in "DU".

Appendix


Measurement Data / Load Factor Files Only text files, whose fields are separated by tabulators, can be read. The fields may have different lengths. A file can contain any number of records. A record can be a behaviour of measurement data or a behaviour of a load factor. A record consists of a header row and of a certain number of data rows. The number of data rows is fixed for week and month factors (7 and 12). It mustn't be greater than a maximum value for the other records. The header row must have the following tabulator-separated entries: Name Name of profile or name of element to which the

measurement data should be assigned Type DF = Day factor, WF = Week factor, MF = Month

factor, YF = Year factor, LO = Measurement data of a load, MD = behaviour of a measurement device

Unit A, kA, kW, MW, % Number of data rows description

Day by Hours Characteristic (Day factor) Maximum number of data rows: 96, unit of values: % A data row consists of 3 tabulator-separated fields. Hour 0, 1, 2, ... , 23 Minute 0, 1, 2, ... , 59 Value >= 0

Week by Days Characteristic (Week factor) Number of data rows: 7, unit of values: % A data row consists of 1 field. Value >= 0

Year by Months Characteristic (Month factor) Number of data rows: 12, unit of values: % A data row consists of 1 field. Value >= 0

Long Term by Years Characteristic (Year factor) Maximum number of data rows: 10, unit of values: %

Appendix


The first data row consists of only 1 field (year). It is not counted. The following data rows (maximum 10) consist of 2 tabulator-separated fields. Year Year (4 digits: e.g. 2003) Value >= 0

Measurement Data (day profile) Maximum number of data rows: 96, unit of values: %, A, kA, kW or MW A data row consists of 3 tabulator-separated fields: Hour 0, 1, 2, ... , 23 Minute 0, 1, 2, ... , 59 Value

Example File with 2 records (1 year factor, 1 day factor): YF_LOW_INCREASE YF % 5 Yearfactor: Low increase

1984

1989 1

1995 -0.5

1996 0

2000 0.2

2010 0.24

DF_INDUSTRY DF % 13 Dayfact.: Industry

0 0 50

1 0 48

3 0 49

6 0 54

8 0 92

9 0 96

11 0 100

12 0 98

15 0 92

16 0 92

18 0 83

19 0 80

21 0 70

Harmonic limit file Limits for harmonic can be entered and stored by Excel. The file name has an extension *.gre. The file consists of 5 rows, which are separated by semicolon: Title of the curve

Appendix


1. sub title 2. sub title h Harmonic value Current or voltage value in %.

Example File with 2 curve: VDEW; odd harmonics; not divisible by 3; h; val;

; ; ;5; 6;

; ; ;7; 5;

; ; ;11; 3.5;

; ; ;13; 3;

; ; ;17; 2;

; ; ;19; 1.5;

; ; ;25; 1.5;

VDEW; odd harmonics; divisible by 3; h; val;

; ; ;3; 5;

; ; ;9; 1.5;

; ; ;15; 0.3;

; ; ;21; 0.2;

; ; ;51; 0.2;

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