Abstract:The traditional half-bridge sub-module based modular multilevel converter (HBSM-MMC) cannot block the DC fault current effectively. Thus an enhanced flexible reverse blocking MMC topology (EFRB-MMC) is proposed by improving the HBSMs and adding the bridge damping modules (BDMs). This paper focuses on its fault blocking performance analysis. Both operation principle and fault current limiting mechanism analysis of EFRB-MMC are carried out firstly, and the analytical formula of fault current and clamp voltage are further derived in detail. Moreover, based on the analysis of fault blocking time and device electrical stress, the design principles of key parameters of EFRB-MMC are further proposed. Finally, the simulation results show the effectiveness of the proposed topology.
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