wind farm connections

[johnspark]

Hi everyone,

we are finding our 132/275kV 50hz network inundated with windfarm connection requests. I think it is partly because our Federal govt. is giving green credits for green energy.

The wind farm would be made up of a sufficient no. of induction generators of ~2MW size to make up about 100MW size. The wind farm generators are connected together at 33kV through a step up transformer to our 132kV network.

Does anyone know if single pole reclosing would result in the generators immediately tripping off, or can the generators ride through the fault event until 3 phase supply is restored? Reclosing time would be ~2-5 seconds long.

NB: At this stage it is not known if the generators will be simple induction motors or double wound induction motors with some power electronics.

NNB: I suppose if the step up transformer has a delta in it, it can help prop up the lost phase for the wind farm...
(Most of our 132/33kV transformers are star/star with or without a delta).

Thanking you all for your kind thoughts

cheers johnsparks

 

[SooryaShrestha]

single pole reclosing is good for the stability of the system. But if the wind farm is with single pole reclosing breakers, I think it will do more harm than good. The unbalancing stress on the generator is very heavy and not healthy for the generator. Single pole reclosing is good for transmission system substation connecting major generation on the system. So we do not provide single pole reclosing scheme in power stations. Is not Reclosing time of ~2-5 seconds high?

 

[johnspark]

The reclosing time has been ~2-5 seconds historically. It may be able to be reduced, especially if we are able to dig up the reason for it being this high in the first place. Of course it needs to be slower than the time taken for de-ionisation time to pass.

Thanks SooryaShrestha

 

[RRaghunath]

It is likely that there would be dedicated step up transformers (generation cannot be at 33kV) with delta on the generator side. Thus, there may not be any difficulty with regard to single phase auto reclosing of 132kV lines emanating from the substation. It is worth checking the negative phase sequence current withstand capability of the generators (may be it will permit the generator protection to ride through the 2-5sec duration.

 

[johnspark]

Yes rraghunath,
there will be a 33/132kV step up transformer, but generally our system would use a star / star transformer, nevertheless, we could have a delta put into the transformer for single phasing ride through. The winding would not need to be very big because it only needs to support the lost phase for a few seconds.