Static var generator using self-commutated inverter

Abstract

A static var generator using self-commutated inverter being able to resume its operation securely and smoothly immediately after a system grounding accident disappears and whose system can be stabilized securely after the accident is provided. The static var generator using self-commutated inverter of the present invention is provided with an accident-detecting circuit 21 comprising band pass filters 22a and 22b extracting the second harmonic components contained in active voltage feedback signals Vp- and reactive voltage feedback signals V.sub.Q -, comparators 23a and 23b comparing these output signals and a prescribed set value and judging of the occurrence of an accident, and an OR circuit 24 operating logical sums of these both output signals. Further, the static type power generator of the present invention comprises a reactive current reference zero controlling circuit 20 controlling a reactive current reference signal I.sub.Q * to be zero according to the detected outputs of the accident-detecting circuit 21, and a soft starting circuit restricting return speeds of the reactive current reference signal at the time of the release of the reactive current reference zero control.