A Submodule Topology for Modular Multilevel Converter with Self-cleaning Ability of Direct Current Fault

The half-bridge submodule (HBSM) of modular multilevel converter (MMC) cannot block the fault current of direct current (DC) side short circuiting alone, but with the aid of alternating current (AC) circuit breaker. To solve the problem, this paper designs a hybrid topology of similarity half-bridge submodule (SHBSM), based on the HBSM of the MMC control system. The hybrid topology can automatically clean the fault current of DC side short circuiting at a low cost, with a relaxed requirement on modular packaging. Then, the author set up a double-ended MMC-high voltage direct current (HVDC) system to identify the MMC fault self-cleaning capacity of the SHBSM. The fault cleaning effect of the hybrid topology was simulated on PSCAD platform. The results show that, despite a small cost increment, the MMC-HVDC with the SHBSM topology can automatically clean the DC fault current, while retaining the advantages of the HBSM. The proposed hybrid topology can solve the high requirement on trigger consistency, that is, all IGBT pulse signals must be blocked at the same time to clean DC fault current. © 2019 Lavoisier. All rights reserved.