A Clustered Voltage Balancing Method of Star-Connected Cascaded H-Bridge STATCOM Under Unbalanced Grid Voltage

Static synchronous compensator (STATCOM) is a widely used reactive power compensation equipment. During the unbalanced power grid fault, the normal operation of STATCOM is a common concerned challenge, especially the resulting phase clustered voltage imbalance. After an explicit vector diagram analysis, a novel phase clustered voltage balance control method based on zero-sequence voltage injection is proposed. The proposed control method is simple to implement, with fast response, and does not need to acquire the negative sequence component of the grid voltage. In addition, a zero-sequence phase locking method is discussed to avoid potential system instability. Finally, the proposed control method is verified by detailed simulation.