A Fault-Tolerant Control Strategy for the Delta-Connected Cascaded Converter

This paper proposes an open-delta operation as the fault-tolerant control strategy for the delta-connected cascaded converter. Based on the detailed power analysis, the fault-tolerant control enables continued operation and maintains dc capacitor voltages balancing during the occurrence of bridge cells fail. This enhances the system's reliability and availability. The simulation and laboratory test-bench, combining a seven-level delta-connected cascaded converter apply in a STATCOM operation and a PV system is tested to verify the proposed control technique.