Abstract：The main circuit and control mode of sub-module(SM) based on modular multilevel converter(MMC) are introduced. On the basis of the fault mechanism, the technical requirements of element was proposed,and the short-circuit protection action time is calculated too. Through discussing the protection strategy for VT1 short-circuit fault, a novel protection strategy with added SCR in the original circuit topology of SM is put forward to ensure the scope of fault controllable, and the mechanical switch would be replaced with it. Finally, the correctness of protection strategy is indicated by PSCAD simulation, and the added reversed SCR is important to the timeliness and effectiveness of the protection.
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2015, Vol. 30 
