Power Imbalance

In my working place we have 3 turbines SGT 300, driven unit is power generator, these turbines sharing the power output, usually 2 turbines are running and the other is standby. There is a problem with these turbines, the problem is power imbalance, meaning that in sometimes a power output imbalance occur, in one turine the generator power output suddenly inceasing and the power of the other generator decreasing and this power imbalance causing trip of the turbine which its power output increased, it trips with alarm COMBUSTION CAN FLAME FAIL , also tempreature deviation occurring.

Please can you advice what possible reasons for this power imbalance?

Thank you

1) When did this problem start? After a trip or shutdown? After a maintenance outage? Has this been ongoing since commissioning, and if so how long ago was commissioning?

2) Does your working place supply power to a utility grid, or a nearby process plant?

3) Does your working place supply power to a nearby process plant and also usually exports some power to a utility grid?

4) If your working place powers a nearby process plant and usually exports some power to a utility grid, does the problem you are attempting to describe occur when the working place and nearby process plant get separated from the utility grid?

5) If your working place supplies power (either full time or occasionally) when utility grid power is unavailable, how is the frequency of your working place controlled? Is there some sort of ”power management system” that sends signals to the turbine control systems to control frequency?

6) When the GT trips, what else is going on at your working place?

7) What happens to the frequency when this problem starts--and up to and after the GT trips?

It appears, based on your question and the information provided, you are relatively new to power generation and are unfamiliar with the design and configuration of your working place (which I am presuming is the power plant, but may, in fact, be a process plant which relies on the power plant for electrical power and possibly even steam).

It is extremely difficult for us to answer your question(s) without knowing a lot more about the design and configuration of your working place--by which I mean the gas turbine -generator power plant.

I'm going to guess that the turbine-generators supply power to a nearby process plant and are also usually exporting a small amount of power to a utility grid. When the utility grid gets separated from the turbine-generators and the nearby process plant the turbine-generators are supposed to maintain power (at rated frequency) to the nearby process plant. But sometime recently this has stopped happening with the results you are attempting to describe.

One possible scenario is that the power management system which would be trying to control frequency when separated from the utility grid is failing to properly recognize the separation of the utility grid and is not sending the proper commands to the turbine-generator control systems, thus resulting in two turbines both trying to control frequency, which could make them ”fight” for control resulting in the behaviour you are attempting to describe. (This would happen if both turbine control systems were switched to Isochronous Speed Control at the same time after the utility was separated from the facility.) And that presumes there is a power management system of some kind--there may not be, or if there is it may be called something entirely different.

But really that is just a guess because there is a LOT we don't know about the situation which you haven't told us. Answering the questions above would help is to understand the situation a little better, but you need to provide answers to ALL the questions, not just a few.

All we can really say is what you have already surmised: Something is amiss. If we knew more about the facility and the situation and when the problem you are attempting to describe started we could probably be more help, but, really, there are lots of possibilities and lots of possible causes.

If you want help, we need lots more information--and if you're new to the facility and power generation you might not be able to provide the necessary information. We can try to help if you are willing to provide more information, but if you aren't willing or able there's nothing more we can add.