Fast Windfarm Active and Reactive Power Response on Distribution Systems

[drchaos]

Hi All,

I have a query about windfarm dynamic active and reactive response on a distribution network:
Is there any reason why a distribution system operator would not want a windfarm to
a) Recover its active power quickly following a voltage dip e.g. within about 0.5 - 1 second?
b) Provide fast transient reactive response during the voltage dip?

In particular, would the response affect the operation of distribution protection relays ?
I am thinking of windfarms fairly deeply embedded in the distribution system, possibly connected
on feeders that have other loads or generation on them.

I'd appreciate any light anyone can shed on this.

Thanks

 

[dpc]

The main reason would be the concern that the response of windfarm would cause more problems than it solves. Voltage dips on distribution feeders are generally created by faults. The utility's main concern will be keeping the feeder energized while downline protection clears the fault, or getting the substation breaker reclosed back into the line if it operated to clear the fault. They would not want the windfarm, or any other generator to stay on-line after the substation feeder breaker opened. The utility's life is simplest if all the generating sources are tripped off-line for any fault on the feeder and brought back on-line only after the fault is cleared and the line is re-energized from the normal substation source.

 

[drchaos]

Thanks for that, DPC. If we had an embedded conventional generator that was not on the faulted feeder, are you saying that any sort of response that might confuse the protection is undesirable? This is confusing I know because of all the many different distribution topologies that can occur, and the many different places that the generation can be located, relative to a fault.

 

[dpc]

Generation on the non-faulted feeders is generally not nearly so much an issue, as long as the total fault current will not exceed the breaker's interrupting rating. But what if the faulted feeder has another generator on it and your helpful voltage support creates issues with the undervoltage protection at the other generator. The utility will have to be able to deal with multiple distributed sources on each feeder, not just yours.