substation automation systems -...

Specification ofIEC 61850 basedSubstation Automation Systems

Klaus-Peter Brand

IEC 61850 Specification March2005 /

LecturerLecturer

Member of CIGRE WG B5.11 (Chairman: Fernando Cobelo)“The introduction of IEC 61850 and its impact on protection and automation within substations”, Lead author of chapter 6 “Specification”

K.P.Brand. Marco Janssen “The Specification of IEC 61850 based Substation Automation Systems”,Paper presented at the DistribuTECH 2005, January 25-27, San Diego

Consultant for ABB pilot SA projects with IEC 61850


IEC 61850 IEC 61850 complex for the usercomplex for the user??ExistingCommunication Standards

User

Developer

User

COM

PLEX

ITY

New StandardIEC 61850

User

Developer

Developer

COM

PLEX

ITY

“Assembler”“Assembler”

“MS Office”“MS Office”


Difference in SA specification with IEC 61850 ?Difference in SA specification with IEC 61850 ?

To see if there is a difference between the specification

of Substation Automation Systems without IEC 61850

or with communication based on IEC 61850

we have to summarize

� what is specified by IEC 61850 and

� what not not specified by IEC 61850

To see always the context we have to keep in mind

what has to be specified for SA in general.


IEC 61850: What is standardized and what not ?IEC 61850: What is standardized and what not ?Standardized

Not standardized

� Data model with LN, DO, Attributes� Services� Configuration Language (SCL)� ICD file (requested) and other SCL based files

� LD and higher plant identification designations� Functions � Allocation of functions to IEDs� Redundancy� Tools and engineering process

� For the stack, a switched Ethernet with priority tagging

� SA concepts and architectures


SA specification and IEC 61850SA specification and IEC 61850The specification has to specify also non-standardized items like availability in such a way that an SA system results

� which fulfils the Basic requirements of an SA system

� preserves the goal of Interoperability acc. to IEC 61850

� with conditions, which allow to limit the flexibility of the Ethernet to on reasonable architecture(ring, star, mixed)

The idea of IEC 61850 is not to make a free choice of anything but to the best system out of the user requirements !


Scope and SA structureScope and SA structure

Stationbus

Processbus

Basic functionality and common structures will stay at least for the next future

Stationgateway

Stationcomputer

HMIStationlevel

Control Protection Protection& Control

Control ProtectionBaylevel

Process Interface Process Interface Process InterfaceProcesslevel Switchgear/Switchyard

Cu wires


Examples for Specifications of SA until now (1)Examples for Specifications of SA until now (1)

New substations� Part of the overall substation specification

� Taking into account all relevant interfaces

� SA specification interacts with various substation specifications:� Switchgear specification

� Auxiliary supply specification

� Control center specification

� Protection system specification

� Etc.


Retrofit substations

� Stand-alone specification

� Referring to the dedicated requirements of the existing substation as boundary

� All functions specified either functional and/or by predefined devices

� Process interface is given by the switchgear

� Established by communication between all IEDs

� Stringent performance requirements

Examples for Specifications of SA until now (2)Examples for Specifications of SA until now (2)


Main question

� What has to be changed since the standarddoes not standardize functions?

Main aspects to be considered

� Functionality and data to be communicated

� Performance and availability requirements

Difference in SA specification with IEC 61850 ?Difference in SA specification with IEC 61850 ?


Basics of specification� Single Line Diagram was and is the basis

� Functional behavior and performance as done before

� Specification of control centre interface

� Specification of process interface (parallel/serial)

Comments� Specifying more than functional requirements, e.g. devices limits

the supply of an optimized system

� There may reasons for such specifications, e.g. go get following SA same as the first optimized one

Stepwise approach to Specification: BasicsStepwise approach to Specification: Basics


Specification of functions

� Specified functions define the Data model

� Mandatory data are always included

� Optional data or extensions have to be specified

Comments� Task of the supplier is to fulfill the functional requirements with the

implemented data model

� Depeding on the implementation, the data models will notbe identical by all suppliers, especially at LD level and above, and by extensions

Stepwise approach to Specification: Data ModelStepwise approach to Specification: Data Model


Logical Device (LD) with the data model

Q0_GGIO+-

Pos

stVal

-

ctlVal

-

-Logical Device (LD) continued with LN GGIO

Pos.stVal

LPHD+

Q0_CSWI+Q0_XCBR+-

Pos

stVal

-

ctlVal

-

-

Q1_XSWI+-

Pos

stVal

-

ctlVal

-

-

Extension by project specific data point for abreaker drive

Extension of LN Q0_XCBRwith name space concept

Extension by LN GGIOwith prefix Q0 (Q0_GGIO) ?

Data Model: Alternatives in case of extensionsData Model: Alternatives in case of extensions



� Specified functions define the Services

� Some services like reporting are given by functionality requirements

� Some services like GOOSE are given by real-timerequirements

Comments

� Nearly all services are fixed both by requirements and theimplementation of the suppliers

� Some properties of the services may be defined

Stepwise approach to Specification: Services (1)Stepwise approach to Specification: Services (1)



� Event driven services like reporting, GOOSE and SV have starting conditions (control blocks) which may be specified

� Some services like reporting, GOOSE and SV have data sets which have to be defined that the results fits to the required signals

Comment� The data model is the maximum amount of data which is provided to

the user

� The data sets define to a large extent what may be found from the entries of the specified signal list

Stepwise approach to Specification: Services (2)Stepwise approach to Specification: Services (2)


Specification

� Geography or geometry of the site� Operator room

� Bay houses

� Cable channels and ducts

� Power supply system

� Process interfaces

Comment� This is a normal process independent of IEC 61850 but may be have

some impact on the allocation of communication equipment and design of communication topology

Stepwise approach to Specification: BoundariesStepwise approach to Specification: Boundaries


BU 1 BU 2 BU 3 BU 4

HMI GW


Specification in the context of IEC 61850� IEC 61850 has not defined redundant communication but leaves this

issue to the “external” communication system as such

� The Ethernet ring provides a ring redundancy which is 100% interoperability if standard means (“spanning tree”) are applied

� Provider specific redundant solutions are using at least proprietary supervision means regarding the liveliness of the redundant links

Comment� Proprietary solutions may be clever but impact the interoperability

� An interoperable solution in the framwork of IEC 61850 is missing

� Specify availability or failure scenarios and request non-proprietary solutions as far as possible to get a solution fitting to your needs

Stepwise approach to Specification: RedundancyStepwise approach to Specification: Redundancy


BU 1 BU 2 BU 3 BU 4

HMI GW

IEC 61850: Open point redundancyIEC 61850: Open point redundancy

Recovery time between 1 ms and 400 ms (100 ms) ?

Supervision and switchover of the second link ?


Specification of pre-defined components, systems, architectures

� Should be specified very carefully

� May restrict optimization process

� Not all performance and availability requirements specified may be reachable given predefined components, systems or architectures.

Comment for re-use of non IEC 61850 components

� Calls for an individual migration strategy

� Migration staregies may be very individually

Predefined items


Specification of responsibility for system integration

� Multi-vendor IEC 61850 SA systems requires detailed definition of supplier responsibilities

� Integration of components fulfilling the specified behavior and performance is responsibility of the system integrator

� Roles must be defined in specifications and other tendering documents and should be properly negotiated

Comment

� All responsible people have not only have the know-how but also the appropriate tools to fulfill their jobs

System integration


System integrator� IEC 61850 is not providing plug-and-play systems. It may be the

basis (embedded SCL ?) for it (definition?) in some distant future

� The system integrator has the full responsibility that the system is running according the specification including functionality, performance and communication

Who is the system integrator ?� May be any party which is able to do the job including know-how,

tools and to take the consequences (claims, etc.)

� Role has to be firmly negotiated

Comment� Responsibility shifted to the system integrator. May be the same party

as in the past

Shift of responsibility ?


Formal specification with SCL

Specification without formal descriptions� The specification of IEC 61850 conformant SA systems can be made

without formal descriptions same as SA specifications in the past

� Specfication with use the SCL allows to specify all features of IEC 61850 in a formal format resulting in files to be used for engineering tools

Comment� An SCL based Specification tool would produce e.g. an SSD file and

reduce misunderstandings and delivery times

� Specifications without SCL have to be translated by the suppliers and system integrators into SCL files

� A typical transition phase


System specification description (SSD) file

SystemDocumentation

files

Dev

ice

Sel

ectio

n

Systemconfigurator

Single LineDiagram(S/S spec)

Feeder Block Diagram(function spec)

Device (IED)

System Configuration

Description (SCD) file

IED Capability De-scription (ICD) file

Device specific

tool

SCD file part per

IED

SCL files

The Engineering Process with SCLThe Engineering Process with SCL

Formalspecificationwith SCL


� Proper specification was and will be the starting point for a clear offer and user’s satisfaction

� “The introduction of IEC 61850 and its impact on protection and automation within substations” is studied in Cigré SC B5 WG11 to be published 2005/2006

� The Cigré work covers the specification in detail, and adresses also user benefits, procurement, testing, commissioning and maintenance

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