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We have two GE power generation gas turbine feeding our gas field. before five days GT I tripped on reverse power. we checked, there is no any abnormalities then we started ok. Today again GT II tripped on same reason and there is no any abnormalities. then we started again.
What could be the reason? also we confirmed that there is no any start of any big motor to cause a surge.

Many thanks

Can you give us some more information to let us try to analyze your problem? You say you have 2 GTGs, are these in an islanded mode or connected to a network. Which governor mode are the machines running in, Droop or Isoch? and which governor mode is the machine which trips on reverse power running in?

Not enough information. Are these units being operated in island mode?

If so, how?

1. After synchronization you should raise the load at least up to 10% as fast as possible. Don't keep it too long under zero or negative generator output.

2. If (1) above is not the problem then look at the stability of fuel flow.

3. If (2) is also not the case, please check your droop percentage set point. The setting might be too low, meaning that bigger response relative to the dynamic of grid frequency.

I need your feedback about the above before going further.

hi Dear, can you advice, how to check droop percentage set point? and how to correct. unfortunately we still have the same problem.

Hello, Dear,

The latter paragraphs of this thread provide a clue as to how a power island should be operated--either manually or automatically:

http://www.control.com/thread/1357683036#1357835439

It's virtually impossible for us to help you with your problem, because we don't have enough information and you haven't provided the information we have requested. When you ask for help, and someone needs more information to be of help, it's rude not to provide the requested information and still continue to ask for help with your problem.

I venture to say that the problem is not related to either Droop- or Isochronous Speed Control. It's more likely a problem of perception--someone perceives the units should be operated or should operate in a particular manner in island mode without understanding how units DO operate in island mode and HOW to operate units in island mode. Even with a good PMS (Power Management System) trying to control frequency and the load(s) of multiple units, it's still necessary for operators to understand how units should operate, how they should be operated, and how to operate them when the "automation" isn't working as well as it should be or is believed to be.

If you would provide more information (as previously requested by more than respondent) about how the units are being operated, the nature of the load, and when problems are being experienced you might be pleasantly surprised at the information you would receive in return. If you continue to say, "It's not working. How do I fix it?" you are probably going to continue to be frustrated with the responses, or the lack of them.

It's your choice. Help us to help you, or, stop asking for help.

Every site is different. Every site is operated differently. Every site has operators and technicians with different training and experience. While your problem may seem simple to you and that others must have seen exactly what you are seeing (which you haven't told us!), then it's going to be very difficult to provide assistance.

Try searching the control.com site/archives for information. Droop- and Isochronous Speed Control has been covered ad nauseum in many posts and in many ways.

Try telling us more about how the units at your site are being operated and what the nature of the load they are trying to supply is and provide the information requested, even if you think it's not relevant at this time. Again, help us help you.

we solved the problem, we found the breaker F3 which transmit the signal from PT to the reverse power relay malfunctioning and has loose connection. after replacing it become ok. thanks all