chapter10 dcs ff july 08 v3 1 oct

8/8/2019 Chapter10 DCS FF July 08 v3 1 Oct

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Topic 3Topic 3 -- 11EEB5223/EAB4223 Industrial Automation & Control Systems

EAB4223/EEB5223EAB4223/EEB5223

Industrial Automation and Control SystemIndustrial Automation and Control System

• PART 3:DCS and Fieldbus

Assoc Prof Dr Nordin SaadDepartment of Electrical & Electronics EngineeringUniversiti Teknologi PETRONAS23.03.005Email: [email protected]: 05-368 7835




This course cover topics related to measurements(PLTF) and automation in the process industry. Theseinclude a study on industrial sensors and actuators, industrialcontrollers such as computer-based control, PLC, DCS and FF.

This course cover topics related to measurements(PLTF) and automation in the process industry. Theseinclude a study on industrial sensors and actuators, industrialcontrollers such as computer-based control, PLC, DCS and FF.

Synopsis

SynopsisSynopsis Learning Outcomes

Learning OutcomesLearning Outcomes

that students are expected to achieved aftersuccessfully completing the course

that students are expected to achieved aftersuccessfully completing the course

The learning outcomes related to Industrial instruments and Measurements

• Have knowledge andunderstanding of the variousprocess industry instruments,concept of measurements,calibration and configuration

requirements and their applications.• Be able to design and develop a

control loop consisting the processinstruments, based on a prescribedrequirement.

The learning outcomes related to Automation and the implementation of Programmable logic controller

• Have knowledge andunderstanding of the PLCarchitecture and its importance inautomation.

• Be able to develop a PLC programto perform sequential, and batchcontrol.

The learning outcomes related to DCS and Foundation Fieldbus use in process industries.

• Have knowledge andunderstanding of a DCS and itsuse in process industries, andthe features and architecture of aFoundation Fieldbus system, andits improvement over theconventional DCS.

This topic covers the key and base areas of automation in the process industries.

Process , Industrial Instr.& Meas.

Process , IndustrialProcess , Industrial

InstrInstr

.& Meas.

.& Meas.Automation

AutomationAutomation

DCS and Foundation Fieldbus

DCS and FoundationDCS and Foundation

FieldbusFieldbus




CONTENTSCONTENTSq DCS• Overview of DCS (also SCADA)• DCS Definition and Configuration• DCS Architecture

• Advanced Control Developmentq Fieldbus• What is Fieldbus? Features• Why Fieldbus? Advantages• Fieldbus – Function blocks, DD, Configurations,

Implementations

• Issues: Device Descriptions, Interoperability




Block Diagram of Process Contro l Loop

Block diagram of a process control loop

FINAL CONTROLELEMENT

PROCESS

MEASUREMENT

CONTROL

+

-

SETPOINT

PV

SP

OPCONTROLLED

VARIABLEMANIPULATEDVARIABLE




Principle of Controller

Block diagram of a controller

PIDCONTROLLEDVARIABLE PV

SETPOINT SP

A

MMANUALADJUSTMENT OP

A AUTO M MANUAL




Analog vs Digital in Field Signals

Signal

Time

Signal

Time

Continous variableDiscrete signal with onlytwo possible values or

position

Analog Digital




- Data Logging

Computer used to store data forreviewing the data.

Monitor

LT

CPU

Printer

PV

SP

OP

Process

Use of Computer in Process Control




LT

CPU

Monitor

Printer

- Set Point /Super visory Cont rol

Set Point

Process Variable

Computer used to performadjustments of loop setpoints

besides keeping records of

process parameters. Thecomputer using specifiedequations, calculates the setpointbased on the measured variable

Output

Process

Use of Computer in Process Cont rol




LT

CPU

Monitor

Printer

PV1

PV2PV3PV4 Out4

Out3Out2

Out1

- Direct Digital/Centralized Control

The function of controllers weresuperseded by the computer. Acentral computer monitor and

control all the process variables.

PV OP

Controller

Process

Use of Computer in Process Control




History and Development of DCS:History and Development of DCS:

•• In the 1940s…In the 1940s…o Mechanical and pneumatic controllers for

controlling a few process variables: T,P,F.o Coordinated process unit control system was

not possible.o Conservatively for stability rather than

economic performance.





•• In the 1950s…In the 1950s…o Electronic controllers introduced.

o Centrally located in the control roomand wired into the measuring devicesand actuators in the plant

o Provide feedforward dynamic models.o Small pneumatic instruments were also

used.





•• In the 1960s…In the 1960s…o Process computers made their debut.o Assembly of distributed, mutually

independent and dedicated controllers.

Smaller instruments (electronic)

Digital computer




History and Development of DCSHistory and Development of DCS

These dedicated controllers/computers hadwider applications in:

• Decentralised (not distributed) control operation ofprocess plant

• Monitoring and control by local operators• Small plant automation• Partial plant automation• Automation in the laboratory, etc.




History and Development of DCSHistory and Development of DCS•• In the 1970s…In the 1970s…o Introduction of analog system architecture, specialized

computer interface devices and computers with highercapacity and speed of processing

o A centralized control structure was introduced. Itcontained process control computer as its central.

Management Information System

OperatorInterfaceSystem

SupervisoryComputerInterface

ProgrammableLogic Controller

Interface

Controller andData

AcquisitionSystem

Foreign DeviceInterface

(Analyzer etc.)

CommunicationSystem

A general DCS component

•Distributedcontrol system

•CRToperation




Evolution Man-machineinterface

1900

MechanicalMechanicalinstrumentsinstruments

[Field operation][Field operation]

Mechanical +Mechanical +pneumaticpneumaticcontrollerscontrollers

[Signal[Signaltransmission]transmission]

Pneumatic +Pneumatic +electronicelectroniccontrollerscontrollers

[Signal[Signaltransmission]transmission]

Electronic +Electronic +processprocess

computerscomputers[Digital computer][Digital computer]

DistributedDistributedcontrol systemcontrol system[CRT Operation][CRT Operation]

1930’s 1940’s 1950’s 1960’s 1970’s - now




Industrial Control System Evolution

DISCRETE ANALOGDEVICES

MECHANCIAL

DIRECT PNEUMATIC

PNEUMATIC TRANSMISSION

ELECTRIC ANALOG CONTROL

RELAYS

ELECTRONIC LOGIC

PROGRAMMABLE LOGIC

DISCRETESWITCHIN G

DEVICES

CENTRALIZEDINTEGRATED

SYSTEM

DCS

DIRECT DIGITAL CONTROL

SUPERVISORY CONTROL

198019701960195019401930

DISCRETEANALOGDEVICES

DISCRETESWITCHING

DEVICES

CENTRALIZEDINTEGRATED

SYSTEM

1990 2000

FIELDBUS

Industrial Control System Evolution

• Timeline of computer control of industrial processes:Ø Ferranti Argus 200Ø MicroprocessorØ SCADA - (I/Os of 1000 or less)Ø Distributed Control System (DCS) - (I/Os of more than 1000)Ø Communication protocol -Fieldbus/Profibus




PROCESS CONTROLEVOLUTION

1975 1985 1995

R O

I

1975 1985 1995

Analog Control

DCS

R e

t u r n o n

I n v e s

t m e n

t

Another dramatic change is required tocreate an acceleration of value from thecurrent DCS offering .

RS3 by Rosemount

PROVOX by Fisher

IA by Foxboro

Open SystemArchitecture

TDC is Introduced by Honeywell




SCADA System

Screen/Display

Sof tware(Monitor,analysis,control)

Hardware(PLC or

commercia lhardware)

Plan t

Supervisorycontrol

Collectinformation

Transfer tocentral

computer

Indirect control:

• For monitoring and indirect control based on certain set-points.• Changes to a process would have to go through various levels

before being implemented – takes time and cannot be doneimmediately.

Indirect cont rol is its m ain limit at ion




SCADA SystemHost control functionsare restricted to basicoverriding orsupervisory levelintervention.

The SCADA systemallows operators tochange the set pointsfor CVs, and enablealarm conditions, suchas loss of flow andhigh temperature, tobe displayed andrecorded.

The feedback controlloop passes throughthe RTU or PLC, whilethe SCADA systemmonitors the overallperformance of theloop.

PLCs control theCVs of an

industrial process.




Development of DCSDevelopment of DCS

The following essential functions wereconcentrated in the central computer:

Ø Process MonitoringØ Data AcquisitionØ Alarming and LoggingØ Data ProcessingØ Process Control

Centralized control





The main concerns and disadv ant ages of acent raliz ed syst em are:

o Reliability : Very depended on proper functioning of the

central computer. System breakdown results indisruption of production and complete shutdown -prove to be extremely expensive.

o Programming effort and cost : Tailored to theuniqueness of each process and its control system.

o Cost of a centralized computer process control system:Mainframe and large minicomputers are very expensive.





This creat ed t he need of fut ure sy st emsdevelopment.

The system should be such that data should bestored where they have been created and wherethey will be needed. Similar principles hold forthe functions also. Only the data requiredfor”other purposes” within the automationsystem will be distributed.





These lead to the following data and functionsrequirements:

• Local control and supervision of plant should be locatednext to the plant instrumentation.

• Processing of data for higher purposes (optimization, setpoint value calculation, etc.) should be allocated in centralcontrol room.

• Production planning and plant management should besituated closer to the relevant plant management staff.





o Hierarchical automation system structure was introduced popularlyknown as Distributed Control System.

o The operators console in the control room, is connected through ashared communication facility to several distributed local controlunits.

Central ControlRoom (several

computers)

SharedCommunication

Facility

LocalProcessControlUnits

LocalProcessControl

Units



A Distributed Control System (DCS)




DCS Definition and ConfigurationDCS Definition and Configuration

The definition of DCS has changeddramatically over its history. The informationprocessing role of DCS has expanded fast, adding

Advanced Process Control, InformationAnalysis tools, Intelligent Systems andBusiness System Integration capabilities.





DCS has three (3) essential qualities:o DCS distributes its functions into smaller sets of

semi-autonomous subsystems covering specificprocess or geographic areas of the plant complex.The functions generally are:

• Process Analysis and Supervision• Data Collection• Process Control• Storage and Retrieval of Information• Presentation of Information and Reports





DCS has three (3) essential qualities (cont…):o To automate the manufacturing process by integrating

advanced regulatory control logic and procedurallanguages with advanced application packages, expertsystems, including information to support suchmanufacturing enterprise application as:

Ø Production scheduling and dispatchingØ Preventive and predictive maintenance schedulingØ Information exchanges with business and logistics application





DCS has three (3) essential qualities (cont…):o The third characteristic is the system aspect of the

DCS, which organizes information flow betweenthe constituent parts so as to have a single

automation system unifying the semi-autonomoussubsystems.




Basic DCS function

Input Output

Primary & ControlElements

Monitoring InputControl LoopAlarms ( PV & SP )Trend , Log & ReportExecute SpecialProgrammed Logic.




Conventional Controller Vs DCS

Conventional Vs DCS

AUTO

MAN

OC

0

200 ton/hr

0 100

AI AO

HPM/APM

100%

75%

50%

25%

0%

SP

PV

OP%

FIC21765KLB/HR

FLOW21

42.9

31.3

52.8CAS

IP

IP




DCS Definition and ConfigurationDCS Definition and ConfigurationIn DCS, the functions of control system are distributed into

different work areas of a process plant:o Central control room : Operator operation and monitoring

functionso Distributed control stations : Distributed at various plant

locations throughout the process facility, perform thefollowing functions at each location-ü Generation of input signals based on analog

variables and discrete inputsü Generation of output signals to control the actuators

to change the process conditions.o Communication system interfacing – the information is

communicated between the central control room andremote control stations.




DCS System ConfigurationDCS System Configuration

o DCS Configuration comprises of (cont…):

o Comm unication sy stem – Interconnects various systems over whichthey can communicate with each other to meet all functionrequirements. Performs the function of transmitting and receiving ofdigital information from all the systems. consists of one or moreoperator consoles for monitoring and controlling process parametersand performing other process related functions.

o Management Information System : Interconnects various othersystems to extract plant-wide management information withoutaffecting or disturbing plant operations.




DCS ArchitectureDCS Architecture

A physical arrangement of the hardware modules and theselection of software options to satisfy system requirements.

The complexity of a DCS can vary. In the simplest form it

could only be a CRT display and keyboard in the controlroom and a local control unit in the process area connected bycommunication cables.




OPERATOROperation and

monitoringfunctions

OTHERSYSTEMS

Communicationbetween other

systems

ENGINEERSystem

configuration,System

maintenance

Display andoperationfunctions

Man-machinedata-base

Gate-way

Control data-base

Controlfunction

Control data-base

Controlfunction

Process Process

Control Station

Communication system

OperatorStation

Process Interface

Man-machine Interface

E n g

i n e e r i n g

I n t e r f a c e

I n t e r f a c e

t o o

t h e r

s y s

t e m s

Various configurations are possible

LCU- Local Control UnitUsually dedicated to specificunit operations of a process.

If CPU or communicationsystems fails, LCU can keepcontrols of the plant.

LCU controller moduleinterfaces with fieldinstruments

CPU – CentralProcessing UnitAllows DAQ and controlfunctions to be performed viaLCUs





Single control loop diagram

I/O SLOT NO 07

WTTV61

APM 1

01NETWORK NO

SLOT NO

03

02

01

02

FTA-ID

MU-TAOX02

J21

+

-

1

2

FTA-ID

2

1 MU-TAIH02

01

01

WTT161

APM 1

01NETWORK NO

NODE NO

MODULE NO

SLOT NOI/O SLOT NO

DCS TAG NO

WTTIC61

REGCLNIM

NODE NO

SLOT NO

CTLACN-REVERSE

03

01

0106

NODE NO

MODULE NO

TB2

TB3

01 TB1

TB1

03

04

3

4 4

3

WT301

WT302

WT301

WT302

TE61+1A1

TE61-1A1

WT307

WT308

WT307

WT308

TCV61+1A0

TCV61-1A0

J22

TE61

TCV61

FIELD JUNCTION BOX TERMINAL PT FTA(DCSCABINET) DCS(CONSOLE)

Control loop diagram of DCS




- Point Trend Display with Four Trace

0.000.000.000.00

EU Low

150.00150.00100.00200.00

EU High % High

100.00

% Low0.00

R-AXIS

AddTrace

ScrollBack

ScrollFwrd

TIC 21741PV

DEG. C73.99

TIC 21741OP

DEG. C28.00

20 MIN HM HM HM

Parameter :EU Desc :

RT Value :

TIC 21741SP

DEG. C71.00

FIC 21741PV

KLB/HR39.00

Function of DCS




0.000.000.00

EU Low

150.00150.00100.00

EU High % High

100.00

% Low0.00

R-AXIS

AddTrace

ScrollBack

ScrollFwrd

TIC 21741PV

DEG. C73.99

TIC 21741OP

DEG. C28.00

20 MIN HM HM HM

Parameter :EU Desc :

RT Value :

TIC 21741SP

DEG. C71.00

Time Base

- Real Time Control

Time Base1 = 1 min2 = 2 min3 = 5 min4 = 10 min5 = 20 min6 = 1 hr7 = 2 hr8 = 8 hr9 = 16 hr10 = 24 hr11 = 48 hr12 = 96 hr13 = hourly14 = shift15 = daily16 = mnthly17 = user

Enter Time Base (1 - 17)

Function of DCS




DCS General Architecture

LT

Printer

ControlStation 1

ControlStation 2

ControlStation 3

DataHighway

User

Interface

Comm.ModuleI/O Module

ControllerModule

I/O Bus

Link

1

2

3

6

5

4




Example of DCS Architecture-Yokogawa DCS Architecture

PF(K)SB's DCS system is segregated into 4domains as shown below :

Domain 1

Amonia andMethanol

Plant

Domain 2Urea,Urea

Granulation andformaldehyde

plant

Domain 3

UtilitySection

Domain 4

Urea ExportTerminal(located at

Butterworth)

PF(K)SB




GUS1

GUS2

GUS3

GUS4

GUS5

GUS6

GUS7

GUS8

GUS9

CCU

Utilities PlantManager'sOffice

Amonia Urea

Area 1 - Amonia Area 2 - Urea Area 3 -Utilities

UnitA1

UnitA2

UnitA3

UnitU1

UnitU2

UnitU3

UnitB1

UnitB2

Area 4

Point, Unit, Area and USRelationship

TT 21242TCV 21242FT 21442

FCV 21442

Points

Unit

Area

Terminal




ü Located in central control stationü Console deskü Keyboard – special functions for graphic and other

displays, programming and command.ü Displays on CRT – group displays showing a group of

control loops, in instrument panel like appearance.

§ Operator Interface :





• Analog input modules:o 4 – 20 mA DC

o 1 – 5 volt DC

o Some DCS accept low level input fromthermocouples/RTDs.

• Discrete input modules (sense switch inputs):

o 24 volt DC, 48 volt DC

• Analog output modules:

o 4 – 20 mA DC

• Digital inputs and outputs modules:

o 24 volt DC, or 120 volt AC

§ Input/Output Modules :





Advanced Control DevelopmentAdvanced Control Development§ Hierarchy of a DCS

Corporate Information System

Process Model and Optimization

Supervisory Control

Regulatory Control

Measuring Devices

PROCESS

Level 4

Level 3

Level 2

Level 1

Level 0




The system when specified along with a supervisorycomputer, could also meet the following requirements inaddition the basic process control.

§ Advanced Control§

Management information system and interfaceto Enterprise resource planning (ERP).

Note : ERP creates an enterprise-wide transactionbackbone and integrate manufacturing financial,

and other systems.

Advanced Control DevelopmentAdvanced Control Development




Advanced Process Control

DCSs and other types of digital control systems areenabling technologies. They provide the infrastructurethat allows substantial improvements in plantoperations.

To realize these improvements, the multivariablepredictive control (MPC), and other model-basedadvanced control technologies, and advancedcontrollers are incorporated.




T i 3 58

Management Information System

and Interface to ERPWhenever information network is specified, the system shallmeet any or all of the following requirements:o Centralised information system

o Statistical process control/statistical quality controlo Plant optimisation

o Plant planning and scheduling

o Computer integrated manufacturing (CIM) – to achieve functionslike production and preventive maintenance, scheduling and plantwide co-ordination, etc.


chapter10 dcs ff july 08 v3 1 oct

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