Abstract:Modular Multilevel Converter (MMC) based on Paralleled Full-bridge Sub-modules (P-FBSM) obtained attention in high-level applications due to its good self-voltage equalization capability and good current passing capability. At present, the research on P-FBSM-MMC focuses on its self-voltage equalization characteristics, while there is less analysis of DC fault blocking mechanism. In order to study the fault current suppression capability and recovery capability of the P-FBSM-MMC system in the case of DC-side bipolar short-circuit, the fault current path of the P-FBSM-MMC in the event of a DC-side bipolar short-circuit fault is first analyzed. Then, the 21-level P-FBSM-MMC and Half-bridge Sub-modules(HBSM)-MMC simulation model was built on PSCAD/EMTDC simulation software, the fault current, DC side voltage and fault recovery capability of P-FBSM-MMC under DC-side bipolar short-circuit fault were analyzed. The conclusion was verified by comparison with the HBSM-MMC simulation results: the P-FBSM-MMC can effectively suppress the fault current by blocking all IGBTs in the event of a DC-side bipolar short-circuit fault, and the DC voltage can be restored to the rated value within a short time after the IGBT is unblocked, which has great reference value for the future research of P-FBSM-MMC.