Diseal Generators Parallel Operation

Hi Kuppali,

Is it back synchrone ? if its, you can check RETRASNFER TIME, do not too fast if you have unstable load, cause its very hard for DGs to keep freq and volt follow the changing. Btw, when the DGs got online/parallel for a moment what was the cos phi ?, did you synchronizing and loadsharing manual or auto ? If manual you see the problem, but if auto check if you have only consider frequency as reference to synchrone, better both freq and voltage match to be parameter of synchrone. And try to find KW or KVAR gain parameter.

Good luck......

Try changing the settings (Power Setting and/or the time delay setting) in the reverse power relay.

You'll need to give some more information for us to better understand.

You said that you have 11kV DG 7sets. Is it one of these generators that is tripping off or is it the main? Is your ATS open transition or closed transition? Has this system been running fine and you have a new problem appear? Is this a new system being commissioned and started?

If it is a single gen tripping when the system is unloaded then you may just have a governor setting that is slightly off compared to the others in the system.

If it is your main tripping then I would assume that your ATS is operating in closed transition. Verify that because if it is open transition there should be no way for power to go back. If the ATS is operating closed transition then you need to determine whether it has active load/unload control.
If the system does not have load control then the ATS usually is intended to only be closed in parallel for a cycle or two and you should set your generator system to be about .05 - .1 hertz faster than the utility so the gens "push" slightly when transferring.
If the system does have active load/unload control across the ATS then you need to first make sure it is functioning and controlling correctly. Usually a problem occurs with this because engineers will program it so it unloads all the way down to zero and you can get reverse power in the time it takes to open. It also can be unloading too fast and cause problems that way.

Let us know what you find and if you have solved it.

Good luck....

Dear Sir,

Its a Open Transition ,Some time 2 Dg's were tripping Some times 3Dg's were tripping.Out of 7 DG's 3Dg's were existing Dg'S(MTU) & 4Dgs's are hooking to existing DG's.

I hope this detail is enough.

Regards

Murali

Hi Kuppali,

I see you have OP trans, how is voltage stability during DGs run single ?, and what about drop in frequency and voltage ? you must make it all the same drop, if not it will cause the different freq and voltage beetween DGs, result reverse power ofcourse. It very hard to get the same drop freq and voltage.

Wish you luck bro...