Research on the Fault Characteristics of DC side Based on MMC-HVDC

The modular multilevel converter has been widely used in the field of flexible HVDC project in recent years because of its high output voltage quality, low harmonic content, low switching frequency and low loss. In view of its special topology, it is necessary to study and analyze the fault characteristics of MMC-HVDC and design the protection. Therefore, the fault mechanism of DC side positive or negative line to ground fault and line to line fault in MMC-HVDC are analyzed in this paper, and the fault simulation study in PSCAD/EMTDC is conducted. We summarized the fault characteristics of these two kinds of faults and put forward the protection strategy. The simulation results verify the correctness of the fault mechanism analysis and the effectiveness of the protection strategy.