Mathematical models of a three-level advanced static VAr compensator

Two mathematical models of an advanced static VAr compensator (ASVC) are 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, 4 kVAr hardware model of a three-level ASVC. The time-domain model was also validated using computer simulations carried out with the EMTDC program. Two switching strategies were considered in the study: fundamental frequency modulation (FFM) and selective harmonic elimination modulation (SHEM). The time domain model was used to predict the waveforms at various parts of the ASVC circuit, for both switching strategies.