Big Job on Idul Fitri

In the Idul Fitri holiday, Java Bali load profile usually very low. This was the right moment for short outage. The time only have 3 or 4 days for cleaning condenser water box, electrical unit transformer isolator, modification control logic or any others planned repair which needs the unit shut down.


After the dispatcher (Jakarta Control Center) has given the unit to de-synchronize, big job for operator was beginning. The scenario was units 20 de-synchronize at 03:00 following with boiler box up and unit 10 still follow JCC load profile.




Boiler Box Up is the way to try to maintain the boiler still hot condition for unit warm start up next. After de-synchronize, top up the level of boiler drum, shut down fans group, keep close all vents and drain, keep air heaters in service.


Electrical unit board 2B was planned to be switched to unit 01 board 1B so equipments which supply from 10 kV and 3 kV from board B should be shut down while process unit shut down. That was BFP B 2x50% and CWP B 2X50%. CEP 1x100% should be use A. The last Pulverizers are service should be A&E. The Compressor is important equipment should be use board A for electric supply and cooling supply should change over to unit 01. Emergency board which supply seal oil, turbine lube oil pump and turning device also should be supplied from board A.

So these are the steps:

Normal Shut Down, Pulverizers in service are A,B,C,D, and E
23:45 Set Load to 520 MW.
Feeders Speed average are 40T/h
Shut down 5th Pulveriser (2B).

00:45 Set Load to 380 MW.
Feeders Speed average are 40T/h
Shut down 4th Pulveriser (2D).

At Load 300 MW supply aux steam auto change from Cold Reheat to Main Steam Platen.

02:00 Set Load to 210 MW.
2nd BFP (2B) is out of service at 765 T/h (each BFP at minimum capacity)
Shut down 3rd Pulveriser (2C).

02:15 Set Load to 180 MW.
Shut down 2nd PA Fan (2B)
Change Co-ordinate Mode to Base Mode.
Start oil burner at Feeder speed 2x30 T/h.

02:30 HP by-pass start opening at 110 MW
Maintain opening 20%

02:45 Shut down Extraction steam master at 70 MW.

Set Load to 10 MW by EHC load control.

03:00 At load 10 MW.
De-synchrone, initiate turbine trip initiate open filed CB.

After de-synchrone,
Shut down BFP conversion master at feed water flow 450 T/h.
Shut down 2nd Pulveriser (2A)
Shut down 1st Pulveriser (E)
Stop Seal Air Fan.
Shut down 1st PA Fan (2A)
All LCS retract.
Top Up Level on Steam Drum
Make sure Turning Gear engage and MSOP auto start when turbine stop.

04:00
Boiler Box Up.
Air Heaters keep in service.
Shut Down Fans Group.
Boiler vents and drain keep close.
FD fan OD close, ID Fan ID close.

Equipments still in service
Condenser Vacuum System
CEP 2A
Vacuum Pump 2A
Gland Steam Exhaust 2A

Feed water System
Steam Drum already Top Up, Steam Drum DT minimum.
BFP 2A
BFP 2B Aux Pump
BFP 2C Aux Pump

Cooling System
CW Pump 2A (stop CW Pump 2B)
Sea Water Booster Pump 2A
Close Cooling Pump 2A
Compressor cooling supplied from unit 01.

Instrument Air
Compressor A

Emergency Board A
Main Seal Oil Pump
Seal Oil Recirculation Pump
Seal Oil Vacuum Pump
Main Oil Pump
Turning Gear Oil Pump
Turning Device

Turbine Generator
Stator Cooling Pump 2A
EHC Pump 2A

Equipments which used power suply from 10 kV only CEP, CW Pump and BFP, they were already used board A, so Board B ready to swithced from generator transformer 2B to unit 01 board 1B

05:00
Electrical Switch Board B from Unit 2B Generator Transformer 22kV/10kV to Unit 01 board B
1.Close 380V ESP Tie CB, and then open 380V outgoing CB from 10kV/380V transformer.
2.Close 380V Tie CB, and then open 380V outgoing CB from 10kV/380V transformer.
3.Close 3kV Tie CB, and open 3kV outgoing CB from 10kV/3kV transformer.
4.Open incoming CB from 10kV/380V ESP transformer.
5.Open incoming CB from 10kV/380V transformer.
6.Open incoming CB from 10kV/3kV transformer.
7.Open incoming CB from Unit 02B Generator Transformer 22kV/10kV.
8.Close incoming CB from Unit 01 10kV board B.

Change Over 10 kV Equipment
9.CW Pump A to B
10.CEP A to B.
BFP can be stop for not over current when switching.

Electrical Switch 3kV from board 2A to 2B
11.Start Compressor B
12.Close 3 kV incoming CB from 10kV/ 3kV transformer.
13.Close 3 kV outgoing CB from 10kV/3kV and board 2B and Open 3 kV outgoing CB from 10kV/3kV board 2A
14.Open incoming CB from 10kV/3kV board 2A.

Electrical Switch 380V from board 2A to 2B
15.Close 380VESP incoming CB from 10kV/380V transformer board 2B
16.Close 380V ESP outgoing CB from 10kV/380V transformer board 2B and Open 380V ESP outgoing CB from 10kV/380V transformer board 2A
17.Close 380V incoming CB from 10kV/380V transformer board 2B
18.Close 380V outgoing CB from 10kV/380V transformer board 2B and Open 380V outgoing CB from 10kV/380V transformer board 2A
19.Open incoming CB from 10kV/380V ESP transformer board 2A.
20.Open incoming CB from 10kV/380V transformer board 2A.
21.Open incoming CB from 10kV/3kV transformer board 2A.
22.Open incoming CB from Unit 02A Generator Transformer 22kV/10kV.
23.Close incoming CB from Unit 01 10kV board A.

Unit 02 electric power already supplied from unit 01.
Next step is open DS from 500kV to unit 02


24.Open CB1
25.Open CB2
26.Open DS1
27.Open DS2
30.Open DS Unit 02
31.Close DS1
32.Close DS2
33.Close CB1
34.Close CB2

Please read 500kV switching for refresh.