REACTIVE DROOP VS. VOLTAGE CONTROL

[duki]

We have 3 generators rated 30MW running in parallel not connencted to the grid. They are run in reaactive droop mode and not in speed droop. What does reactive droop actually mean. If one generator would trip, the load, both real power and var would increase on the other two generators. What would happen to the bus voltage and why. Is it possible for the AVR to adjust the voltage back to the normal level.

 

[ScottyUK]

Reactive droop is a means of ensuring the machines share the reactive load. If all three machines were in voltage control with the same target voltage there would be slight differences between them due to tolerances. The unit which would produce the highest voltage if it were islanded will hog the reactive load when part of a group. Reactive droop causes the AVR to back off the field excitation slightly, shifting the VAr loading in a leading direction.

If one unit were to trip the active and reactive loads will redistribute onto the remaining generators, assuming that they have capacity to accept the additional load. The voltage should recover quickly to nominal level.


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If we learn from our mistakes I'm getting a great education!

 

[waross]

Speed droop and reactive droop are not related.
Speed droop is a characteristic of the governor and reactive compensation adjusts the voltage so as to share the reactive current.

Bill
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