Ride-Through of Switch Failures in Cascaded HBridge Based STATCOM Based on Model Predictive Control Strategy

Ride-through of switch failures is one of the most important issues for stable operation of cascaded H-bridge (CHB) converters. In this article, a straightforward faulttolerant control strategy based on model predictive is proposed for a three-phase star-connected 7-level CHB-based static synchronous compensator (STATCOM). After occurrence an open circuit in a H -module, one voltage level is removed in the faulty phase of the inverter. To maintain the operation of three-phases uniform, one voltage levels is discarded in the rest normal phases of CHB. On this basis, the switching states are re-arranged in post-fault condition as the control system inputs. Then, using a multi-objective model predictive control (MPC), the optimal switching states in each sampling period has been selected and applied to the converter. The simulation results indicate that the STATCOM continues operation after fault with injecting reactive power whereas the voltages of dc capacitors voltages are stabilized.