Loss evaluation for modular multilevel converter based on equivalent-aera modulation

The result of the research on the loss of the modular multilevel converter (MMC) based valve for HVDC power transmission is seldom reported. Due the distinctive feature of MMC topology, the methods to calculation the loss of traditional loss calculation methods for thyristors and insulate gate bipolar transistors (IGBT) cannot be directly applied to MMC valve. Combining with the switching characteristic of the distinctive semiconductor devices of the sub-module of MMC valve, the physical process of switching on/off the sub-module of MMC valve is analyzed; considering the topological structure of the converter and equivalent-area modulation algorithm, the relation among the loss of MMC valve and its valve current, and modulation algorithm voltage under typical operating condition is derived. The research result is available for reference to the loss reduction design for MMC-HVDC transmission systems.