Diesel Generator work with Wind Generator

We have a 2 by 275kW wind power generators connected to a system with two generators one giving a maximum of 500kW and the other 180kW both having speeds of 750 rpm. All these are to supply a load of about 470kW normal hour and a peak load of about 650kW. The problem is one diesel generator (500kW in this case) is not able to be supply load when interconnected with the wind turbines due high frequency swings (47Hz to 53Hz and the diesel gen-set finally falling off) to reduce this effect we are forced to run both generators when wind power is available, in this scenario the frequency swing is about 48.5 - 51.5Hz. Hence the question of which machine can complement wind power generation fluctuation best? High speed, low speed, medium speed or is it a question of fitting a more dedicated governor/electronic control unit on the diesel engine generators.

I take it that generator speed and Hz of power produced are one and the same thing only that one is mechanical and there is the electrical equivalent. I am more concerned in frequency (50Hz), but more so on how fast a diesel generator can recover back to 50Hz or ability to maintain 50Hz after a sudden loss of a wind turbine generator or wide margin of power produced by a wind generator (due to variation of wind strength) resp. the wind turbines generators and the diesel generators are connected in one system. Now if I compare types of diesel generators (500kw) and we take it that we have lost a wind turbine which was producing 200kw while the diesel generator was producing 300 Kw (hence total load was 500kw), the diesel generator will be forced to peak up the load dropped by wind generator.

  1. Comparing diesel generators of low speed, medium speed and high speed which one will pick up the 200kW faster (as it strains to pick the load the speed rpm and hence Hz will drop) and come back to a frequency of 50Hz (Kenyan power system standard)
  2. Does it really matter the rated speed of the machine or is entirely up-to the governor/electronic control unit to match/deliver required power. OR
  3. Both the rated machine speed (in terms low speed, medium speed and high speed) and the governor/electronic control unit settings matter in achieving the desired corrective action.

The wind turbines and the diesel generator are connected to supply load in a common network whereby the diesel generators are the reliable source as it is easily controlled and also as a reserve in case wind generation is lost, the wind turbine generators are used as supplement but cannot be controlled easily hence relies on nature greatly but then saves generator fuel whenever it is supplying power.

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