Design aspects of a square-wave Series Voltage Compensator

Among several solutions for the voltage sag problem, the Series Voltage Compensator (SVC) stands out. This device injects a compensating voltage at the moment the sag occurs, recovering the voltage supplied to the protected load. The injected voltage is usually produced by a PWM inverter in series with a LC filter, producing a sinusoidal compensating voltage (Sinusoidal SVC). Instead of using sinusoidal voltage waveforms, the authors claim that line frequency square-wave compensating voltages yield more cost effective solutions. For instance, in a square-wave SVC, the LC filters and high switching frequency losses are eliminated. This paper presents several square-wave SVC topologies, including a cost comparison between sinusoidal and square-wave solutions. It is demonstrated that the square-wave SVC is more cost effective than the sinusoidal one.