MATHEMATICAL-MODELS OF A 3-LEVEL ADVANCED STATIC VAR COMPENSATOR

Two mathematical models of an advanced static VAr compensator (ASVC) a re described. One model was obtained using time-domain analysis of the ASVC circuit and then developed into an s-domain model which was used to study the compensator's control system. Both models were validated using a three phase, 4kVAr hardware model of a three-level ASVC. The time-domain model was also validated using computer simulations carrie d out with the EMTDC program. Two switching strategies were considered in the study: fundamental frequency modulation (FFM) and selective ha rmonic elimination modulation (SHEM). The time domain model was used t o predict the waveforms at various parts of the ASVC circuit, for both switching strategies.