A new simple method for capacitors voltage balancing in cascaded H-bridge SSSC

Abstract

Static Synchronous Series Compensator (SSSC) is one of the FACTS devices which has wide applications. Recently its usage has been more practical and economical by using multilevel and especially cascaded H-Bridge topologies. In this paper a cascaded H-bridge SSSC is represented which has a modular structure and lower switch stress than common SSSC. The biggest problem of the cascaded structures is unbalanced DC voltage of the cascaded modules. A new simple and practical method is represented that can compensate the voltage difference due to capacitance tolerance. This idea is suitable for PWM modulation and expected that will not change the switching frequency.