The sub-module”s (SM”s) capacitor voltage balancing problem of modular multilevel converters (MMCs) is one of the technical difficulties demanding prompt solution in the MMC engineering application.In contrast to the traditional voltage balancing method which uses the sorting results of SM capacitor voltages according to the direction of the arm current,this paper proposes an improved and optimized method by introducing the double holding factor to reduce the switching frequency and losses.Meanwhile,the voltage balancing strategy of packet sorting is adopted in the proposed method to maintain the relative balance of energy between the SMs by introducing the energy balancing factors on the premise of ensuring normal operation of MMC.The optimized voltage balancing method has realized reduction of the sorting operand and improvement of the capacitor voltage sorting speed.The model of MMC with ten SMs is realized by PSCAD/EMTDC,with both correctness and effectiveness of the proposed method verified by simulation results.%模块化多电平换流器(MMC)的子模块(SM)电容电压均衡问题是MMC工程应用急需解决的难点之一。文中针对采用电容电压进行排序，根据电流方向触发导通的传统电压均衡方法进行了改进和优化，引入了双保持因子，降低SM的开关频率，以减小开关损耗。同时，还通过引入能量均衡因子，使SM间的能量保持相对平衡，在保证换流器正常运行的前提下，对桥臂 SM采用分组排序的均压策略，从而达到减小排序运算量，提高 SM电容电压排序速度的效果。最后，通过在PSCAD/EMTDC下搭建11电平的 MMC 仿真模型，对所提出的方法进行了验证，仿真结果证明了所提出的优化均压方法的正确性和有效性。
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