Limitations of the H-bridge multilevel STATCOMs in compensation of current imbalance

In this paper we investigate limitations of H-bridge multilevel STATCOMs in the compensation of current imbalance in industrial applications. In either star or delta topology of the STATCOM converters, the zero sequence injection is used to balance power flows (i.e. to balance dc bus capacitor voltages) in the arm converters. In imbalanced situations the compensation capability of the current imbalance is limited by the level of the required zero sequence injection.