distributed control system

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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 And Integrated On Same

Communication Loop.

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 Pre-

Determined 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.

All healthy nodes and all are at same

hierarchy

NODE SERVER MASTERLESS TYPE DCS

Bus1

Bus2

Node 1

Node 4

Node 3

Node 2

Node 6

Node 5

All healthy nodes and all are at same

hierarchy

Node 1

Node 4

Node 3

Node 2

Node 6

Node 5


Bus1

Bus2failure

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

nodes

failure

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


Bus1

Bus2

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.

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.

CLIENT SERVER WITH SINGLE NETWORK

Server healthy means all nodes (clients)

communicating to the server

Server Client 1

Client 4

Client 2 Client 3

Client 5

CLIENT-SERVER ARCHITECTURE TYPE DCS BUT MASTER LESS FOR OPERABILITY

Bus1

Bus2

Server healthy means all nodes (clients)

communicating to the server

server Client 1

Client 4

Client 2 Client 3

Client 5

CLIENT- SERVER ARCHITECTURE TYPE DCS BUT MASTERLESS FOR OPERABILITY


nodes

Bus1

Bus2failure

Even after failure of server, the clients

keep communicating in between and hence

operability is intact

Client 4

Client 3

Client 5

Failure

Failure of server renders failure of communication

between clients and server

Client 2Client 1Server

CLIENT SERVER ARCHITECTURE TYPE DCS BUT MASTERLESS FOR OPERABILITY

Bus1

Bus2

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.

serverClient 2Client 1 Client3

Client 4Client 5

CLIENT SERVER ARCHITECTURE TYPE DCS WITH SERVER AS MASTER

Network I /Bus1

Network I /Bus2

Network II /Bus1

Network II /Bus2


Client 4Client 5

CLIENT SERVER ARCHITECTURE TYPE DCS WITH SERVER AS MASTER

Network I /Bus1

Network I /Bus2

Network II /Bus1

Network II /Bus2

failure


nodes


Client 4Client 5

failure

Data lost

Data lost

ErrorErrorError

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

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

BOILER-1 BOILER-2 BOILER-3 COMMON

NIS NISNISNIS

NPM NPM NPM NPM

NODE-4NODE-1

NODE-2

NODE-3

ITC ITC ITC ITC ITC ITC

NIS NIS NIS NIS NIS NIS

LINE-1

LINE-2

NODE-5NODE-10

NODE-6NODE-9 NODE-7NODE-8

REDUNDENT C - NET

O-NET

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/OUTPUTS-

1)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

NIS NPM

BRCSLAVETU

C-NET

BRC

C-NET

SLAVETU

TO FIELD

FROM FIELD

DATA FLOW BETWEEN BRC AND C – NET

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 Is Windows 2000

Professional Based.

HIS P HIS R CLIENT COMPOSER

RTDS1 RTDS2EWS

O-NET

ABC SEQ BMS TG-1 TG-2 COM

C - NET

ARCHITECTURE OF CPP DCS SYSTEM

COMPARISON OF DCS OF SGP & CPP OF NFL PANIPAT

SGP• Architecture is

Node Server based.

• Operating system is Window XP Professional based.

• All critical loops are redundant

• DCS is PGP based

CPP• Architecture is

Client server based.

• Operating system is Windows 2000 professional based.

• All critical loops are not redundant .

• DCS is PPB based.

COMPANY ABB YOKOGAWA

S.NO. MODEL

Advant with 460 controller

Syphony Harmony IT Infi-90 CS 3000 CS 1000

1HMI Architecture Node Server option

Node Server option Client Server Node Server Client Server

2Operating System Window Based Window Based Window Based Window Based Window Based

Window NT Window NT or XP Window NTWindow NT,XP,2000 Window NT,2000

3 Data Bus Using C-Net 10 MbpsUsing C-Net 10 Mbps

Using C-Net 10 Mbps

Using V-Net 10 Mbps

Using VL-Net 10 Mbps

4 Redundancy

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 extraPresent 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

DCS COMPARISON OF VARIOUS MODELS OF VARIOUS COMPANIES

COMPANY ABB YOKOGAWA

S.NO. MODEL

Advant with 460 controller

Syphony Harmony IT Infi-90 CS 3000 CS 1000

5 Processor

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

6Online Replacement Yes Yes Yes Yes Yes

7Online 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 posibleSutable 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




11 Scan time<200ms Possible Possible Possible Possible Possible


COMPANY FOXBORO HONEYWELL SIEMENS

S.NO. MODEL IA Series Experience PKS TPS with gus Teleperm XP Telemerm ME

1 HMI Architecture Node Server option Client ServerNode Server option Node Server Client Server

2Operating System Window Based Window Based Window Based Window Based DOS Based

Window NT,XP,2000 Window NT,XP,2000 Window NT STRUK

3 Data BusUsing Device-Net 10 Mbps

Using LAN Up to 100 Mbps

Using LCN 5 Mbps

UsingCS-272 <10Mbps

4 Redundancy

A) Power Supply Yes Yes Yes Yes Yes

B) System Bus Yes Yes Yes Yes Yes

C) Controller Yes Yesoptional with extra

optional with extra optional with extra

D) I/O Module Present in critical loop optional with extraoptional 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


COMPANY FOXBORO HONEYWELL SIEMENS

S.NO. MODEL IA Series Experience PKS TPS with gus Teleperm XP Telemerm ME

5 Processor

A) System User Defined User Defined User Defined User Defined INTEL PII

B) Controller N/A C 200 N/A Virtual ProcessorINTEL 80188(20MHz)

C) Controller Memory 4000Kb 156Kb

6Online Replacement Yes Yes Yes Yes Yes

7Online 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 only for medium plant

10 Web ConnectionPossible with isolation



Possible with isolation N/A

11 Scan time<200ms Possible Possible Possible Possible Possible


distributed control system

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