大幅减小子模块电容容值的MMC优化方法  

Optimized Method of MMC for Greatly Reducing the Capacitance of the Submodules

作　　者：董鹏[1] 蔡旭[1] 吕敬[1] DONG Peng;CAI Xu;LU Jing(Electronic Information and Electrical Engineering Wind Power Research Center of Shanghai Jiaotong University,Minhang District,Shanghai 200240,China)

机构地区：[1]上海交通大学电子信息与电气工程学院风力发电研究中心

出　　处：《中国电机工程学报》2018年第18期5369-5380,共12页Proceedings of the CSEE

基　　金：国家重点研发计划课题(2016YFB0900901);上海市科委科研计划项目(16DZ1203402)~~

摘　　要：减小子模块电容容值能够降低模块化多电平变换器（modular multilevel converter,MMC）的成本、体积和重量,具有重要的工程意义。该文首先建立半桥、全桥和混合MMC的子模块电容电压波动统一模型,揭示出基频和2倍频波动是主要分量。在此基础上,提出一种结合2倍频环流和3倍频共模电压注入及优化调制比来减小子模块电容电压波动的方法。以混合MMC为例,结合其运行的约束条件对调制比、子模块数量、控制策略和子模块容值选取进行优化设计。所提优化方法能够将子模块电容容值减小为常规的约1/3,同时降低换流器通态损耗并保留直流短路故障处理能力。仿真结果验证了理论分析的正确性和所提优化方法的有效性。Reducing the capacitance of the sub-modules （SMs） can reduce the cost, size and weight of a modular multilevel converter （MMC）, which is of great engineering significance. Firstly, a unified model of capacitor voltage fluctuation of SM in half-bridge, full-bridge and hybrid MMC was established, which shows that the fundamental frequency and second-order harmonic components were dominated. On this basis, a method combining the second-order circulating current, third-order common-mode voltage injection and optimizing the modulation index was proposed to reduce the capacitor voltage fluctuations. Taking the hybrid MMC as an example, the optimized design for the modulation index, number of SMs, control strategy and SM capacitance was presented with consideration of the operation constraints of the hybrid MMC. The proposed optimal method is able to reduce the SM capacitance to about one-third of the conventional method. Meanwhile, the proposed method can reduce the on-state losses and preserve the DC short circuit fault handling capability. The correctness of the theoretical analysis and the effectiveness of the proposed optimized method was validated by simulation results.

关 键 词：模块化多电平变换器 电容减小 调制比 环流注入 直流短路故障处理能力 优化 

分 类 号：TM46[电气工程—电器]