混合MMC电容电压波动差异机理及抑制策略  

Mechanism and Suppression Strategy of Capacitor Voltage Fluctuation Difference in Hybrid Multilevel Modular Converter

作　　者：陆锋 李钰 樊强 赵成勇 许建中 屈海涛 LU Feng;LI Yu;FAN Qiang;ZHAO Chengyong;XU Jianzhong;QU Haitao(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources (North China Electric Power University),Beijing 102206,China;Beijing DC Transmission and Distribution Engineering Technology Research Center (C-EPRI Electric Power Engineering Co. ,Ltd. ),Beijing 102200,China)

机构地区：[1]新能源电力系统国家重点实验室(华北电力大学),北京市102206 [2]北京市直流输配电工程技术研究中心(中电普瑞电力工程有限公司),北京市102200

出　　处：《电力系统自动化》2019年第17期92-101,共10页Automation of Electric Power Systems

基　　金：国家电网公司科技项目“适用于架空线路的柔性直流换流阀系统关键技术研究”(52130A180002)~~

摘　　要：降低模块化多电平换流器(MMC)中子模块电容电压纹波幅值,有望降低对子模块电容器容值、体积、成本的需求,具有重要的研究价值。文中首先分析了混合MMC过调制下半桥子模块与全桥子模块的电容电压波动特性以及两种子模块间的波动差异产生机理,确定波动差异对应的能量积累区间。然后分类讨论三次谐波电压注入后桥臂参考电压的极值点分布和过零点分布,建立三次谐波电压注入系数、调制比与波动差异抑制能力的关系。在此基础上,以减少半桥子模块与全桥子模块电容能量积累差异为目标,对三次谐波电压注入量进行优化设计,提出了基于三次谐波注入优化的子模块电容电压波动差异抑制策略,并给出电容容值降低的计算示例。最后,在PSCAD/EMTDC中搭建双端混合MMC模型,仿真结果验证了理论分析的正确性和所提方法的有效性。Reducing the amplitude of the capacitor voltage ripple of the sub-module in the multilevel modular converter(MMC)is expected to reduce the capacitance, volume and cost of the sub-module capacitor, and has important research value. This paper analyzes the characteristic of the capacitor voltage fluctuation and the fluctuation difference between half-bridge and full-bridge sub-modules with over-modulation in hybrid MMC, which determines the corresponding energy accumulation interval. Then, the extreme point distribution and zero crossing point distribution of the arm voltage reference with the third harmonic voltage injection are discussed. The relationship among the injection coefficient of third harmonic voltage, the modulation index and the fluctuation difference suppression capability is established. Aiming at reducing the difference of capacitance energy accumulation between half-bridge and full-bridge sub-modules, the third harmonic voltage injection quantity is optimized, and the suppression strategy of capacitor voltage fluctuation difference based on the third harmonic injection optimization is proposed. Then an example of calculation for reducing the capacitance is presented. Finally, the correctness and validity of the proposed strategy are verified by the simulation of double-end hybrid MMC in PSCAD/EMTDC.

关 键 词：模块化多电平换流器 子模块电容器 过调制 波动差异 三次谐波电压注入 电容电压波动抑制 

分 类 号：TM721.1[电气工程—电力系统及自动化]