DCS Control System
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WHY DCS ? DCS stands for Distributed Control System which provides an Automation platform For controlling the plant process & Control Systems with optimum accuracy & efficiency. Incorporating DCS enables remote communication with all the field devices from the Control Room. The DCS has got processors which can process the signals really fast & can command the field devices i.e. Control Valves, Pneumatic Dampers, VFD-Motors, Pump’s Scoop-Control, Burners etc. to control the various process parameters viz. Press. , Temp. , Flow , Level , Load , Speed/Frequency etc.
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Transcript of DCS Control System
WHY DCS ?
DCS stands for Distributed Control System which provides an Automation platform For controlling the plant process & Control Systems with optimum accuracy & efficiency.
Incorporating DCS enables remote communication with all the field devices from the Control Room.
The DCS has got processors which can process the signals really fast & can command the field devices i.e. Control Valves, Pneumatic Dampers, VFD-Motors, Pump’s Scoop-Control, Burners etc. to control the various process parameters viz. Press., Temp., Flow, Level, Load, Speed/Frequency etc.
DISTRIBUTION
• Functional Distribution.
• Geographic Distribution.
SIGNAL TYPES AI AO DI DO
Press. Transmitters
Level Transmitters
Flow Transmitters
RTD & Thermocouple
LVDT-Position T/X
Control Valves
Scoop Control
Motors-VFD
Dampers
Limit S/W
Pressure S/W
Torque S/W
ON-OFF Valves
Solenoid V/V
ON-OFF Valves
ON-OFF Dampers
RELAYS-TRIP Coils
Signal: 4-20 mA Signal: 4-20 mA Signal: 0-24 V Signal: 0-24 V
Source: ABB-DCS / DPL-300 MW
AI - MODULE
AO - MODULE DI - MODULE DO - MODULE
Input channels Input channels Input channels
Input channels
DCS - Configuration
Therefore as expected we have 4 basic input & output [I/O] modules called;
AI – Modules 4-20 mA AO -- Modules 4-20 mA DI – Modules 0-24V DO – Modules 0-24V
CI – Module: Comm. Interface which is the media of communication b/w IO Modules& the Controller.
• CI-MASTER: with Controller.
• CI- SLAVE: with the I/O modules.
Controller: AC – 800 M is the controller with microprocessor PM – 864 [speed 96MHz / 32 Mb RAM].
Profibus: We have a process field bus connection b/w the I/O Modules & the Controller.Further the Controllers are connected to the Engineering Station & Operating Stations via Serversthrough Fiber-Optic cables.
Source: ABB-DCS / DPL-300 MW
DCS – An Overview
Source: ABB-DCS / DPL-300 MWCI - MASTER
CI - SLAVE
CI - SLAVE
CI - SLAVE AI / AO / DI / DO - RACK
AI / AO / DI / DO - RACK
AI / AO / DI / DO - RACK
FIELBUS COMMUNICATION
Panel Configuration of a Typical DCS
Front View: showing the Controllers, Ethernet Switches & The Field Bus.
Rear View: showing the I/O Modules, the Power Distribution & JB connections.
DCS - Architecture
Source: ABB-DCS / DPL-300 MW
MAJOR BOILER CONTROL LOOPS MAJOR TURBINE CONTROL LOOPS 1. Furnace Draft Control Loop. 1. Speed/Frequency Control Loop. 2. 3-Element Control Loop. 2. Hotwell Level Control Loop. 3. Fuel Flow Control Loop. 3. Gland Sealing Press. Control Loop. 4. Air Flow Control Loop. 4. Lube Oil Control Temp Control Loop. 5. De-Aerator Level Control Loop. 5. Turbine Vacuum Control Loop. 6. De-Aerator Pressure Control Loop. 7. PRDS Control Loop.
8. Superheated Steam Temp. Control Loop.
VARIOUS CONTROL SYSTEMS IN A POWER-PLANT
De-Aerator Level Control
Deaerator Level Control Valve
Level T/X
4-20 mA as AI
A / D Converter
Binary Signals 0 & 1
D / A Converter
Binary Signals 0 & 1
4-20 mA as AO
Furnace Draft Control Loop
ID Fan Damper
De-Aerator Pressure Control Loop
Press. T/XPressure Control Valve
Superheated Steam Temp. Control Loop
Thermocouple
Spray Control Valve
3 ELEMENT DRUM LEVEL CONTROL LOOP
Press. T/X
ThermocoupleVFD – Drag Chain Feeders
Combustion Control Loop Fuel Flow Control Loop
Combustion Control Loop Air Flow Control Loop
Hotwell Level Control Loop
Level T/X
Hotwell Control Valve
Scoop Control
PRDS - Pressure Control Loop
Press. T/X Press. Reducing Valve
PRDS – Temp. Control Loop
Thermocouple/RTD
Spray Control Valve
Speed/Frequency Control Loop
WOODWARD – 505 E
AI AO
Remote SP
FIELD FIELDDCS
Interlocks
Auto/Manual Stn.
I
A/M
AI- Module AO- Module
WOODWARD 505 E
Press. T/X.Pr
LT-A LT-B PT FT FT
1 out of 2 Logic
PID 1/3 E
+
PID
MVR-SP
30 % Control Valve100 % Control Valve
FEED-FLOWSTEAM-FLOWDRUM-PRESS.DRUM-LEVEL
C-SP
MV
I/PI/P
FIELD
DCS
FIELD
4-20 mA
AO- CARD
AI- CARD
I
A/M
AI- Module AO- Module Turbine Control ValveSpeed Sensor
LOAD [MW]
Main Steam Pr.
Extraction Pr.
I
A/M
Trip SpeedF + F
F-Speed F - F
VFDDrag Chain Feeders
Combustion Control Loop Fuel Flow Control Loop
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