Fault Localization Strategy for Modular Multilevel Converters in Rectifier Mode Under Submodule Switch Open-Circuit Failure

The modular multilevel converter (MMC) is a promising candidate for the high-voltage and high-power applications. Fault localization is an important issue for the reliable operation of the MMC. The localization strategies of switch open-circuit failures for the MMCs in the inverter mode have been widely reported in the existing literature. This brief proposed a complete fault localization strategy for the MMC in the rectifier mode. In this brief, the differences of the fault characteristics between the inverter mode and rectifier mode are analyzed in detail. Based on that, the switch signal is used as the criterion for the fault localization. After the faulty submodule (SM) is identified, combining the switch signal and the capacitor voltage of the faulty SM can further locate the faulty switch. The proposed strategy can simplify the localization and identify three kinds of switch failures in SMs. In addition, the validity of the proposed strategy is verified by the simulation results.