Hi all,

I'm new with steam turbine control and operation. It is a combined cycle 100 MW operated steam turbine of Fuji type. yesterday our unit tripped and the alarms generated was
As the follow
1) at 4:37:05 STG power factor
2) at 4:37:06 AVR LIGHT FAULT (30AVR)
3) at 4:37:11 ST 400KV BRAKER OPEN
4) at 4:37:12 GEN. LOSS OF EXCITATION 40G
5) at 4:37:12 Generator Lockout RELAY ON 86G
6)at 4:37:12 LOCKOUT SUPERVISION 74

We stated to combined the two GT-STEAM cycle at 14:50 and all the conditions were stable, the GT Cycle were feeding the the grid with min. Load of 70 MW, the level of the drums of the HRSG were also very stable and all the tempreture and pressure were good.
The grid was stable since there were no problems of operating 6 units of GT and 3 units of steam IN THE samepower plant.
The frequency was stable
No surging spikes
And the weather was fine.
We were able to reset the alarm and normalized everything, and currently the unit is running. We however have yet to understand why the tripping happened and means of preventing it. And did it result from any mistake from the operating Engineer.

any help or advice on it is very much appreciated.

Thank You

 

Hi @Ghaith123

Do you know what control operating mode was the AVR before the trip?
Was it on PF regulation.. Or other mode..

Also can you develop on AVR LIGHT FAULT.. (30AVR)Perhaps you can check alarm ID /CODE NUMBER IN AVR OEM MANUAL..

 

It was on VAR mode.
I am sorry I don't have the manual but I do have the code for the alarm which is
TGB-CABA3108

 

Well something may happened wrong on VAR regulation/control mode

For the code it means nothing for me..

 

Well something may happened wrong on VAR regulation/control mode

For the code it means nothing for me..

 

Try to get event trip log report from AVR OR PROTECTION RELAY

 

I Meant trends/datas may be or can be stored on AVR or Protection relay in event/trip log report ....

 

Ghaith123...
Welcome to Control.Com
Please provide Alarm messages, for all operating machines before and after tripping of the machine in question!
Regards, Phil Corso

 

Ghaith123...
You asked for help, but seem reluctant to provide necessary data!
Regards, Phil Corso

 

Ghaith123...
You asked for help, but seem reluctant to provide necessary data!
Regards, Phil Corso

Sorry for being late, I didn't noticed that you are following up with me.. I am now on two weeks off but I can assure you that the alarm that are associated with trip case are just what I have provided.. All other alarm before and after those alarm are related to drum level, pressure and tempreture s of the various equipments.

 

Ghaith123...
Your mention of a "400kV breaker" suggests a sketch, (preferably a print) of the system Single-Line-Diagram (SLD) would be helpful
Do you have records of V, A, MW, PF, RPM or Hz, data for the 2 paralleled machines before-during-after, the reported event?
Phil Corso

 

Yes I have.. My shift is starting today.. I will attach all the trends to you.. When I saw it.. I noticed a a drop in reactive power and yes the problem is why the high voltage had opened.. It should not be opened as a protection for a Loss of excitation

 

Ghaith123
Not all electrical problems are related to electrical devices. So, please provide the steam flow records of the 2 paralleled machines before-during-after, the reported event!
Phil Corso