A high voltage large capacity dynamic VAr compensator using multilevel voltage source inverter

A multilevel pulse-width-modulation (PWM) voltage-source inverter is connected to a static volt-ampere-reactive (VAr) compensator (SVC) as a large-scale power source. The SVC can be directly connected to AC mains of 6600 V, allowing full utilization of semiconductor devices like gate turn-off thyristors (GTOs). The voltage balancing condition of the DC slide capacitors is identified based on the fundamental circuit modeling of the inverter, and a five-level PWM is used to meet the condition. Owing to the multilevel approach, a low distortion in the input currents results and filter size thus is minimized. To confirm the validity of the fundamental circuit modeling of the SVC system with a five-level inverter, the system was simulated using commercial simulation packages