We have two GE Frame 5, 18 MW Gas Turbines running in parallel, in synchronism. The running load is about 14 MW on each Gas Turbine. One of the Gas Turbine is selected on ISO and other is on droop mode. Since the last one month, we are experiencing problem of variation in power factor. The p.f of one of the Gas Turbines falls to about 0.68, while that of the other rises to about 0.98. The load in Mega Watts remains unchanged. The reactive power of the gas turbine with lower p.f increases. The system voltage also increases from 6.3 kV to 6.42 kV. This lasts for 5 to 10 minutes and then normalizes by itself. Sometimes we also adjust the power factor ourselves by changing the excitation.
We have taken followings actions so far, without any success.
1) Cleaning of slip rings
2) Replacement of Carbon Brushes
3) Have checked the capacitors and electronic components of excitation system of one of the Gas Turbines in an opportunity.
4) The Gas Turbine on ISO was changed over to droop and vice versa. For 72 hours we also run both Gas Turbines on droop mode.
I would appreciate if some one can help us which Gas Turbine to suspect for the problem, possible causes, whether the problem can be outside the excitation system and tips for trouble shooting in synchronized condition.
Regards,
P.F Variations in two Gas Turbines in Synchronism
Re: P.F Variations in two Gas Turbines in Synchronism
