Force-Commutated Reactive-Power Compensator

Abstract

A reactive-power compensator (RPC) is a type of static var compensator (SVC) that is used to dynamically correct power factor to prevent voltage variation (flicker) in ac power sources due to large dynamic loads. It also minimizes total source current. Thus the application of an RPC or SVC to a load may allow addition of substantial new load to existing feeders or substations. A reactive-power compensator suited to industrial ratings (1.0-25 MVA) is described. It utilizes a force-commutated current-source bridge to provide both leading and lagging reactive power. The ability to operate both leading and lagging can reduce by 2:1 the ratings of the RPC itself and the capacitors and magnetics associated with it. The characteristics of the power circuit, the means used to control it, and the resulting dynamic performance is described. Speed of response compares favorably to the thyristor-controlled reactors now in common use as SVC's at higher MVA ratings. This RPC is suited to compensate any balanced three-phase dynamic load.