电网不对称故障下MMC自适应相功率均衡控制策略  

Adaptive leg-balancing control strategy of an MMC in an asymmetric AC grid fault

作　　者：于吉 尹项根[1] 赖锦木 韩翔宇 陈卫[1] 胡家玄 窦真兰 孙沛 YU Ji;YIN Xianggen;LAI Jinmu;HAN Xiangyu;CHEN Wei;HU Jiaxuan;DOU Zhenlan;SUN Pei(State Key Laboratory of Advanced Electromagnetic Engineering and Technology(Huazhong University of Science andTechnology),Wuhan 430074,China;School of Electrical Engineering,Zhengzhou University,Zhengzhou 450001,China;State Grid Shanghai Municipal Electric Power Company,Shanghai 200023,China;State Grid ShanghaiElectric Power Research Institute,Shanghai 200437,China)

机构地区：[1]强电磁工程与新技术国家重点实验室(华中科技大学),湖北武汉430074 [2]郑州大学电气工程学院,河南郑州450001 [3]国网上海市电力公司,上海200023 [4]国网上海市电力公司电力科学研究院,上海200437

出　　处：《电力系统保护与控制》2024年第1期1-12,共12页Power System Protection and Control

基　　金：国家电网有限公司科技项目资助(5400-20219953A-0-5-ZN)。

摘　　要：交流电网不对称故障工况下模块化多电平换流器(modular multilevel converter,MMC)存在相功率不均衡的问题,常规的基于直流环流注入的调控方法会引起桥臂电流不对称,导致各相电流应力不相等;而基于零序电压注入的方法可能导致系统过调制,危害系统安全稳定运行。针对传统相功率均衡控制策略的局限性,提出一种交流电网不对称故障下MMC自适应相功率均衡控制策略。首先,分析基于零序电压和直流环流注入的MMC相间功率调控原理,指出不同方法单独进行相间功率均衡的局限性。其次,研究零序电压注入方法的过调制边界,引入相功率分配系数,给出不同故障下相功率系数优化方法,提出基于零序电压和直流环流注入协调的MMC自适应相功率均衡控制策略。最后,通过仿真验证了机理分析与所提控制策略的正确性和有效性。A modular multilevel converter(MMC)has the problem of unbalanced power in asymmetric fault conditions.The conventional control method based on DC circulating current injection will cause asymmetry of arm current,resulting in unequal current of each phase.The method based on zero-sequence voltage injection may lead to over modulation and endanger the safe and stable operation of the system.Given the limitations of traditional leg-balancing control strategies,an adaptive leg-balancing control strategy of an MMC with asymmetric faults is proposed.First,the principle of leg-balancing based on zero-sequence voltage and DC circulating current injection is analyzed,and the limitations of different methods are pointed out.Second,the overmodulation boundary of the zero-sequence voltage injection method is studied,and the phase power distribution coefficient is introduced.Then the optimization method for a leg-power distribution coefficient with different faults is given and an adaptive leg-balancing control strategy of the MMC based on the coordination of zero-sequence voltage and DC circulating current is proposed.Finally,the correctness and effectiveness of the mechanical analysis and the proposed control strategy are verified by simulation.

关 键 词：模块化多电平换流器 相功率均衡 桥臂电流控制 不对称故障 零序电压注入 

分 类 号：TM46[电气工程—电器]