Distributed Control System

SAGAR BHARDWAJ

EVOLUTION OF DCS Different stages of evolution of Control system are : • • • • •

Manual or Field control Pneumatic Single loop control system. Electronic single loop control system Centralized control system Distributed control system.

DISTRIBUTED CONTROL SYSTEM DEFINATION :•A Control System In Which Different Intelligent

Devices

(Controllers) Are Functionally & Geographically Distributed To

Control

The

Process

Communication Loop.

And

Integrated

On

Same

ADVANTAGES OF DCS SYSTEM REDUNDANCY:- The System Consists Of Critical Equipments Which Have Been Supported By Active Stand By System Which Results In Increased Reliability. RELIABILITY

:- Ability Of A System To Operate Efficiently Under PreDetermined Operating Conditions.

ADAPTABILITY:- Ability Of A System To Operate Under Adverse Operating Conditions Accept Changes And Also Provide Easy Machine Human Interface.

ARCHITECTURE’S OF DCS • The master less deterministic type on single network (Node Server) • The client server type with master less characteristic

on single network • The client server

type with server as master and

interlink between clients on two separate networks.

NODE SERVER • A network with deterministic master less type of protocol has a real master less node hierarchy, which means that all the nodes, i.e., all controllers as well as operator stations will have the same priority and shall be always communicating to the network together. In this case, the failure of any one operator station, i.e. any one node will lead to the “ non operation of that node only and the rest of the system stays healthy ” , thereby maintaining the healthiness of the network.

Node 1

Node 2

Node 3

Node 4

Bus1 Bus2 All healthy nodes and all are at same hierarchy Node 5

Node 6

NODE SERVER MASTERLESS TYPE DCS

Node 1

Node 2

Node 3

Node 4

Bus1 failure

Node 5

Node 6

Bus2

All healthy nodes and all are at same hierarchy

Failure of Bus-2 causes Bus-1 to take over without making any difference to nodes

NODE SERVER MASTERLESS TYPE DCS

failure

Bus1 Bus2

FAILURE OF A NODE WILL LEAD TO THE FAILURE OF THE PARTICULAR NODE ONLY. OPERABILITY IS INTACT FROM ALL OTHER NODES

Still Healthy Nodes keep system healthy

NODE SERVER MASTERLESS TYPE DCS

CLIENT SERVER WITH SINGLE NETWORK A special case of Client-server architecture with servers and all its clients connected directly to the same network. In this architecture both the controllers and the operator stations are clients to the server but communicating directly to the network. All the data required are being stored in a common distributed database at the server which keeps the complete history of the operations and process data.

CLIENT SERVER WITH SINGLE NETWORK In normal operation all the operations and process data are being communicated from/to the operator stations/ controllers are routed through the server, but failure of the server will lead to a direct communication of the operator stations to the controllers. The complete controllability of the controllers from the operator stations stays intact and the only difficulty faced is the loss of the historical trending capability of the control system.

Server

Client 1

Client 2

Client 3

Bus1 Bus2

Client 4

Client 5

Server healthy means all nodes (clients) communicating to the server

CLIENT-SERVER ARCHITECTURE TYPE DCS BUT MASTER LESS FOR OPERABILITY

server

Client 1

Client 2

Client 3

Bus1 failure

Client 4

Client 5

Bus2 Server healthy means all nodes (clients) communicating to the server

Failure of Bus-2 causes Bus-1 to take over without making any difference to nodes

CLIENT- SERVER ARCHITECTURE TYPE DCS BUT MASTERLESS FOR OPERABILITY

Server

Client 1

Client 2

Client 3

Failure

Bus1 Bus2

Client 4

Failure of server renders failure of communication between clients and server

Client 5

Even after failure of server, the clients keep communicating in between and hence operability is intact

CLIENT SERVER ARCHITECTURE TYPE DCS BUT MASTERLESS FOR OPERABILITY

CLIENT SERVER WITH TWO SEPEATE NETWORKS A network with client server architecture will have servers as an interconnection point between the controller nodes and the human machine interface nodes (HMIs). Both the controllers and the HMIs are clients to the server. The failure of the server will lead to a highly dangerous situation of complete loss of controllability of the network. No process information from the controller will be communicated to the operator station and instructions from the operator station also cannot be communicated back to the controller.

Client 1

Client 2

Client3

server

Network I /Bus1

Network I /Bus2

Network II /Bus1 Network II /Bus2 Client 4

Client 5

CLIENT SERVER ARCHITECTURE TYPE DCS WITH SERVER AS MASTER

Client 1

Client 2

Client3

server

Network I /Bus1 failure

Network I /Bus2

Failure of Bus-1 causes Bus-2 to take over without making any difference to nodes Network II /Bus1 Network II /Bus2 Client 4

Client 5

CLIENT SERVER ARCHITECTURE TYPE DCS WITH SERVER AS MASTER

Client 1

Client 2

Client3

Data lost

server failure

Data lost

Failure of the server will lead to failure of complete network and loss of operability

Client 4

Client 5

STEAM GENERATION PLANT OF NFL PANIPAT • Steam generation plant has three Boilers of BHEL make, each having MCR (Max. Capacity Rating) of 150 T/hr respectively, producing superheated steam at a Pressure of 100 Kg/cm2 & at a temperature of 500 0 C • All the three boilers are controlled by DCS.

SGP DCS SYSTEM • Distributed control system for steam generation plant is being procured from M/s ABB . The system is known as

“ WORKSTATION BASED SYMPHONY HARMONY INDUSTRIAL IT SYSTEM”. • The control and monitoring philosophy has been split in to two categories i.e. closed loops and Open loops ( mainly indications). • The closed loops are being powered , monitored and controlled in the DCS whereas the open loops are being powered and configured in the MUX system and monitored in the DCS system.

SGP DCS SYSTEM NODE DISTRIBUTION • There are total 10 nodes in system which are directly connected to C-NET. Sr.No

No. of nodes

Used for

1

Three (3)

Three Boilers

2

One(1)

Common section

3

One(1)

EWS

4

Five(5)

OWS

• The EWS & OWS are also to Ethernet switch through O- NET cable.

• Two printers are on O-NET.

SGP DCS SYSTEM PANEL CONFIGURATION • DCS system panels for each boiler comprises of four panels, one is system panel, and the rest three are termination panel. • AI terminates through HMS panel whereas AO terminate directly , DI/DO terminate through relays. • System panel have three set of controllers in redundant,one for OLCS, one for CLCS & last for MUX. System panel communicates using NIS & NPM. Similarly OWS communicate on C-NET using NIS & ICT.

DATA FLOW

LINE-1 LINE-2

O-NET NODE-9

NODE-8

NODE-7

NODE-6

NODE-10

NODE-5

ITC

ITC

ITC

ITC

ITC

ITC

NIS

NIS

NIS

NIS

NIS

NIS

REDUNDENT C - NET NIS

NIS

NIS

NIS

NPM

NPM

NPM

NPM NODE-4

NODE-1 BOILER-1

BOILER-2 NODE -2

BOILER-3 NODE -3

COMMON

C-NET C-NET is a unidirectional, high speed serial data network that operates at a 10 – megahertz communication rate. It supports a central network with up to 250 system NODE connections.

SYSTEM CARDS •

THERE ARE DIFFERENT TYPES OF CARDS IN SYSTEM PANEL FOR VARIETIES OF INPUTS/OUTPUTS1)TEMPERATURE CARD FOR THERMOCOUPLE/RTD,( IMAS123) 2)ANALOG INPUT CARD FOR 4-20 ma, (IMFEC12) 3)ANALOG OUTPUT CARD FOR 4-20 ma(IMASO11) 4)DI CARD FOR CONTACT INPUT (IMDSI 13) 5) DO CARD FOR CONTACT OUTPUT (IMDS0 14) 6) NETWORK INTERFASE SLAVE (NIS-21) 7) NETWORK PROCESS MODULE (NPM-12) 8) BRC 300 ( CONTROLLER) 9) MFP 12 ( CONTROLLER) 10) ITC- (FOR COMMUNICATING WITH THE COMPUTER)

DCS SYSTEM • 4-20 mA out of smart Txs., Superimposed with hart signal, are terminated to HMS. Here, HART Signal and 4-20 mA signals are separated using patch cards. 4-20 mA goes to terminate to AI cards through DCS Marshelling cabinet. • Termination of this 4-20 mA depends on whether this is field powered or system powered.

MULTIPLEXER SYSTEM • Supplied by MTL,England. • Multiplexers are used for cable saving. Here non critical signals have been taken through MUX. • There are four MUX stations for each boiler installed in field itself. • All the twelve MUX stations having redundant supply . MUX -1 & 2 for each boiler caters mainly AI whereas MUX-3 & 4 caters mainly DI/DOS.

MULTIPLEXER SYSTEM • The MUX uses redundant EBIM (Ethernet bus interface module) processing data at very high speed of 100 Mbps, whereas the controller (MFP12) used in DCS system for third party communication is Modbus compatible, hence MOXA switches are used to convert Ethernet to Modbus.

MULTIPLEXER SYSTEM • Hence redundant Ethernet cable have been laid from each of the MUX to redundant MOXA switches from MOXA, Ethernet Cable been laid for HMS/MUX PC where WORKBENCH Software is loaded for status monitoring of all MUX modules. • Also RS-485 Cable laid from MUX-1 & 2 having AIs only to HMS PC, through RS-485 to RS-232 Converter, for catering smart transmitters with the help of CORNERSTONE Software loaded on the same HMS/MUX PC.

SER-SEQUENCE OF EVENT RECORDER • There is one SER of 512 points comprising of two SER Stations - EL1 & EL2. SER Stations

DI Cards

No of events handling capacity

EL1

9

288

EL2

7

224

DATA FLOW BETWEEN BRC AND C – NET

NIS

C-NET C-NET

TO FIELD

FROM FIELD

NPM

TU

SLAVE

BRC

TU

SLAVE

BRC

CAPTIVE POWER PLANT IN NFL PANIPAT • In NFL Panipat We have Captive power plant which has MCR 230 T/hr at Pressure of 100Kg/cm2 and at a temperature of 500oC • In NFL Panipat we have Two Turbo Generators (TG’s) each having a capacity of 15MW • Boiler of CPP and Turbine of TG’s is controlled by DCS.

CPP DCS SYSTEM 1. Distributed control system for CPP was originally procured from

M/s ABB The system was “ BAILEY NETWORK 90” 2. Later on it was up graded with Symphony Harmony Industrial IT System for turbine side 3. The boiler side is up graded with INFY 90 System. 4. In this way CPP have to separate DCS System. 5. Both systems are connected to a pair of redundant server. 6. CPP DCS System is Client server based Architecture.

NODE DISTRIBUTION OF CPP DCS SYSTEM 1. It Has 16 (Sixteen) Nodes connected to C – NET

Sr.No.

No. of Nodes

Used for

1

Three(3)

Automatic Boiler Controller(ABC)

2

Four(4)

Burner management system(BMS)

3

Three(3)

Sequence (SEQ)

4

Two(2)

Turbine of TG 1 & 2.

5

One(1)

Common Section

6

Two(2)

RTDS 1 & 2

7

One(1)

EWS

OPERATING STATIONS DISTRIBUTION OF CPP DCS SYSTEM  Four

Operating

Station

Are

Connected

Through

Redundant O – Net To RTDS 1 & 2. A. Two Stations Are Loaded with History. B. One Station Is Loaded with Configuration Software.  The

Operating

Station System

Professional Based.

Is

Windows

2000

ARCHITECTURE OF CPP DCS SYSTEM ABC

SEQ

BMS

TG-1

TG-2

COM

C - NET

RTDS2

RTDS1

EWS

O-NET

HIS P

HIS R

CLIENT

COMPOSER

COMPARISON OF DCS OF SGP & CPP OF NFL PANIPAT SGP

CPP

• Architecture is Node Server based. • Operating system is Window XP Professional based. • All critical loops are redundant • DCS is PGP based

• Architecture is Client server based. • Operating system is Windows 2000 professional based. • All critical loops are not redundant . • DCS is PPB based.

DCS COMPARISON OF VARIOUS MODELS OF VARIOUS COMPANIES COMPANY S.N O.

ABB

YOKOGAWA

MODEL

Advant with 460 controller

Syphony Harmony IT

Infi-90

CS 3000

CS 1000

1

HMI Architecture

Node Server option

Node Server option

Client Server

Node Server

Client Server

2

Operating System

Window Based

Window Based

Window Based

Window Based

Window Based

Window NT

Window NT or XP

Window NT

Window NT,XP,2000

Window NT,2000

Using C-Net 10 Mbps

Using C-Net 10 Mbps

Using C-Net 10 Mbps

Using V-Net 10 Mbps

Using VL-Net 10 Mbps

A) Power Supply

Yes

Yes

Yes

Yes

Yes

B) System Bus

Yes

Yes

Yes

Yes

Yes

C) Controller

Yes

Yes

Yes

Yes

optional with extra

D) I/O Module

optional with extra

Present in critical loop

optional with extra

Present in critical loop

optional with extra

E) Server

Yes

Yes

Yes

Yes

Yes

F) Memory(system )

Yes

Yes

optional with extra

Yes

optional with extra

3

Data Bus

4

Redundancy

DCS COMPARISON OF VARIOUS MODELS OF VARIOUS COMPANIES COMPANY S.N O.

ABB

YOKOGAWA

Advant with 460 controller

Syphony Harmony IT

Infi-90

CS 3000

CS 1000

A) System

User Defined

User Defined

User Defined

User Defined

User Defined

B) Controller

68040/25 MHz, Motorola

32- bit, Motorola RISC

32- bit, Motorola RISC

VR5432(133MHz)

Proprietary

C) Controller Memory

Up to 8Mb

16Mb

16Mb

32Mb

6

Online Replacement

Yes

Yes

Yes

Yes

Yes

7

Online Configuration

Yes

Yes

Yes

Yes

Yes

8

System Memory

User Defined

User Defined

User Defined

User Defined

User Defined

9

I/O capacity

>10000 tags posible

Sutable for large plant

only for medium plant

Up to 100000 I/O

only for medium plant

10

Web Connection

Possible with isolation

Possible with isolation

Possible with isolation

Possible with isolation

Possible with isolation

11

Scan time<200ms

Possible

Possible

Possible

Possible

Possible

5

MODEL Processor

DCS COMPARISON OF VARIOUS MODELS OF VARIOUS COMPANIES COMPANY S.N O.

FOXBORO

HONEYWELL

SIEMENS

MODEL

IA Series

Experience PKS

TPS with gus

Teleperm XP

Telemerm ME

1

HMI Architecture

Node Server option

Client Server

Node Server option

Node Server

Client Server

2

Operating System

Window Based

Window Based

Window Based

Window Based

DOS Based

Window NT,XP,2000

Window NT,XP,2000

Window NT

STRUK

Using Device-Net 10 Mbps

Using LAN Up to 100 Mbps

Using LCN 5 Mbps

UsingCS-272 <10Mbps

A) Power Supply

Yes

Yes

Yes

Yes

Yes

B) System Bus

Yes

Yes

Yes

Yes

Yes

C) Controller

Yes

Yes

optional with extra

optional with extra

optional with extra

D) I/O Module

Present in critical loop

optional with extra

optional with extra

optional with extra

optional with extra

E) Server

Yes

Yes

Yes

Yes

optional with extra

F) Memory(system)

Yes

optional with extra

Yes

Yes

optional with extra

3

Data Bus

4

Redundancy

DCS COMPARISON OF VARIOUS MODELS OF VARIOUS COMPANIES COMPANY S.NO . 5

MODEL

FOXBORO

HONEYWELL

SIEMENS

IA Series

Experience PKS

TPS with gus

Teleperm XP

Telemerm ME

A) System

User Defined

User Defined

User Defined

User Defined

INTEL PII

B) Controller

N/A

C 200

N/A

Virtual Processor

INTEL 80188(20MHz)

Processor

C) Controller Memory

4000Kb

156Kb

6

Online Replacement

Yes

Yes

Yes

Yes

Yes

7

Online Configuration

Yes

Yes

Yes

Yes

Yes

8

System Memory

User Defined

User Defined

User Defined

User Defined

User Defined

9

I/O capacity

Up to 100000 I/O

Up to 100000 I/O

10000 tags

10

Web Connection

Possible with isolation

Possible with isolation

Possible with isolation

Possible with isolation

N/A

11

Scan time<200ms

Possible

Possible

Possible

Possible

Possible

only for medium plant