Analysis of Reactive Power Compensation Limit of the Star-Connected Cascaded H-Bridge Converter Under Unbalanced Grid

Under unbalanced grid conditions, the cascaded-H-bridge-based static var compensator (CHB STATCOM) commonly injects zero sequence voltage to balance the stability of the DC voltage of each phase. This paper comprehensively considers the characteristics and device parameters of three types of asymmetric power grid faults based on the zero sequence voltage injection method. It quantitatively provides the reactive power compensation limit of the STATCOM under unbalanced grid conditions. Finally, a simulation using PLECS is built and the results verify the correctness of the analysis.