不对称交流电网下MMC-HVDC系统的控制策略  

Control Strategy of MMC-HVDC System Under Asymmetric AC Grid Conditions

作　　者：董鹏[1] 蔡旭[1] 吕敬[1] DONG Peng;CAI Xu;LüJing(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16期4646-4657,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：在MMC-HVDC系统中,交流电网不对称会导致MMC换流器交流侧电流不平衡、直流侧出现较大的2倍频电流和电压波动等问题。为解决这些问题,该文建立不对称交流电网下MMC-HVDC系统的数学模型,提出一种带有前馈补偿的交流电流、桥臂环流和直流电流的解耦控制策略及子模块电容电压和直流电压的平衡控制策略,避免了由交流电网不对称引起的功率振荡传播到直流系统,抑制了直流侧电流和电压波动,使得MMC在交、直流系统间起到了＂防火墙＂的作用。同时,改善了换流器直流侧电流、交流侧电流、子模块电容电压和直流电压控制的暂态性能。仿真和实验结果验证了理论分析的正确性和所提控制策略的有效性。In the MMC-HVDC system, asymmetric AC power grid will cause unbalanced current at the AC side of the converter, large double-line frequency fluctuations in the DC current and voltage. To solve these problems, the mathematical model of the MMC-HVDC system considering asymmetric AC grid conditions was established, then a decoupled control strategy of AC current, DC current and arm circulating current with feedforward compensation and a balanced control strategy of sub-module capacitor voltage and DC voltage were proposed. The oscillating power caused by asymmetric AC grid system can be avoided to be transmitted to the DC system and the suppression of fluctuations in the DC current and voltage with balanced AC current can be achieved, thus making MMC play a ＂firewall＂ role between the AC and DC systems. Meanwhile, the transient performance of the DC current, AC current, capacitor voltage and DC voltage control can be improved. Simulation and experimental results verify the effectiveness of the theoretical analysis and the proposed control strategy.

关 键 词：模块化多电平变换器 不对称交流电网 解耦控制 暂态性能 电容电压平衡 

分 类 号：TM46[电气工程—电器]