A New MMC Sub-Module Topology with DC Fault Blocking Capability and Capacitor Voltage Self-Balancing Capability

A large number of modular multilevel converters (MMC) are connected to HVDC transmission systems nowadays. This paper aims at the short-circuit fault in DC line system and problem capacitor voltage imbalance MMC, proposing a new type MMC sub-module, which has both self-clearing ability self-balancing ability. sub-module combines topology half bridge full bridge. It uses reverse forcibly turn off conducting diode block current loop. At same time, two capacitances charge discharge states consistent by utilizing operating mode sub-module. is possible directly achieve without complex balancing control. The MATLAB/Simulink simulation verifies effectiveness blocking capability balance proposed