Hi,
I'm after some advice. I'm looking to use the new F series when it arrives in the UK for a circuit breaker load shedding controller.
The general control is as follows, in the below example I'm using one generator with five load circuit breakers. Each of the circuit breakers will have a power meter attached to the outgoing circuit.
The load (kW) will be read from this meter via modbus or the analogue inputs and stored in DM. I will need create an average value from this reading so I know the load through the breaker.
EXAMPLE
1. ONE GENERATOR ON SITE GEN FRAME SIZE 1000KWe
2. AVERAGE SITE LOAD = 1350KWe
3. FIVE LOAD SHEDDING BREAKERS, EACH WITH 270KWe LOAD
4. EACH CB HAS A PRIORITY LEVEL 1-5, 1 BEING HIGHEST PRIORITY.
BLACK START - Mains failed
Input GEN ONLINE = 0
Input LOAD SHED = 1
1. LOAD SHED SIGNAL RECEIVED FROM CONTROL SYSTEM
2. ALL LOADS DISCONNECTED
3. CONFIRMATION SENT BACK TO WITHIN 500MS
4. GEN ONLINE SIGNAL RECEIVED
5. 1ST PRIORITY LOAD STEP CB IS CLOSED (PRIORITY CB # 1 = 27OKWe 27% OF GENERATOR CAPACITY)
6. CALC IN PLC:- NEXT PRIORITY CB # 2 = 270KWe, ADD THIS TO EXISTING LOAD = 540KWe... 54% OF GENERATOR CAPACITY, IS THIS LESS THAN
SETPOINT (85%) IF YES MOVE TO NEXT STEP. IF NO, NO MORE LOADS CAN BE ADDED.
7. YES - ALLOW CLOSURE OF PRIORITY CB # 2.
6. CALC IN PLC:- NEXT PRIORITY CB # 3 = 270KWe, ADD THIS TO EXISTING LOAD = 810KWe... 81% OF GENERATOR CAPACITY, IS THIS LESS THAN
SETPOINT (85%) IF YES MOVE TO NEXT STEP. IF NO, NO MORE LOADS CAN BE ADDED.
7. YES - ALLOW CLOSURE OF PRIORITY CB # 3.
6. CALC IN PLC:- NEXT PRIORITY CB # 4 = 270KWe, ADD THIS TO EXISTING LOAD = 1080KWe... 108% OF GENERATOR CAPACITY, IS THIS LESS THAN
SETPOINT (85%) IF YES MOVE TO NEXT STEP. IF NO, NO MORE LOADS CAN BE ADDED.
7. NO - DO NOT ALLOW CLOSURE OF PRIORITY CB # 4.
8. CALC IN PLC RUNS CONTINUOUSLY TO SEE IF LOAD HAS CHANGED, IF LOAD IS REDUCED CB# 4 MAYBE ALLOWED TO CLOSE, IF THE EXISTING LOADS
INCREASE PAST THE SETPOINT CB # 3 WILL OPEN.
LOAD SHED SIGNAL REMOVED, MAINS RETURN SITE IN PARALLEL
Mains Returns
Input GEN ONLINE = 1
Input LOAD SHED = 0
9. ALL CLOSED LOAD STEPS REMAIN CLOSED.
10. REMAINING LOAD STEP CB'S ARE CLOSED
11. SYSTEM IS RESET.
MAINS FAILS WITH GENERATORS RUNNING
Input GEN ONLINE = 1
Input LOAD SHED = 1
12. OPERATION AS BEFORE HOWEVER IT WOULD BE NICE TO SPECIFY THAT AL LEAST 1 or 2 PRIORITY CB'S REMAIN CLOSED.
13. MAINS RETURNS. OPERATION AS BEFORE.
I was thinking of using three sequences, one for the "black start", one for the "mains returns" and one for the "mains fails with generators running".
Each sequencer will be enabled or disabled from a call function based on the inputs "gen online" and "load shed"
Do you this this is the best way to control this? can you suggest how the call functions and the sequencer functions would interact.
Many thanks.
