面向大容量直驱风电机组的机侧MMC电容电压脉动抑制策略  

Machine Side MMC Capacitor Voltage Ripple Suppression Strategy for High Capacity Direct Drive Wind Turbines

作　　者：杨玉坤 许建中 YANG Yukun;XU Jianzhong(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources(North China Electric Power University),Changping District,Beijing 102206,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),北京市昌平区102206

出　　处：《中国电机工程学报》2023年第16期6300-6312,共13页Proceedings of the CSEE

基　　金：国家自然科学基金项目(52277094)。

摘　　要：模块化多电平换流器(modular multilevel converter,MMC)作为大容量风电机组背靠背变频器具有良好前景,但机侧MMC运行时面临低频工况下子模块电容电压波动幅度大的难题。本文提出一种复合的二倍频环流叠加高频注入策略,通过二倍频环流注入抑制大量电容电压的二倍频纹波,并在此之上叠加高频注入进一步提高低频工况上下桥臂能量交换速度,达到大幅度降低子模块电容电压波动的目的。最后在PSCAD/EMTDC仿真平台搭建仿真模型对所提策略的有效性进行验证。仿真结果显示,二倍频环流注入可抑制44.19%的电容电压波动,叠加高频电压和高频环流注入后可进一步抑制51.6%的电容电压波动,在相同的电压波动要求下降低了对子模块电容容值的需求。所提策略在风速突变下和并网点发生暂态故障期间仍具有有效性,适用于大规模海上风电并网等场景。Modular Multilevel Converters(MMCs)show promise as back-to-back inverters for large capacity wind turbines.But machine-side MMC operation faces the challenge of large capacitance voltage fluctuations in sub-modules under low-frequency conditions.This paper proposes a compound strategy combining doubling circulating current injection superimposed on high frequency.Doubling circulating current injection suppresses double ripple of many capacitor voltages.Superimposed high-frequency injection further increases upper and lower bridge arm energy exchange rates in low frequency operation,significantly reducing sub-module capacitor voltage ripple.A simulation model built on PSCAD/EMTDC verifies effectiveness.Simulations show doubling circulating current injection suppresses 44.19%of capacitor voltage ripple.Superimposed high-frequency voltage and high-frequency circulating current injection further suppresses 51.6%of capacitor voltage ripple,reducing sub-module capacitance requirements for the same voltage ripple.The proposed strategy remains effective under sudden wind speed changes and transient faults at grid connection points,suitable for large-scale offshore wind power grid connection scenarios.

关 键 词：模块化多电平换流器 低频工况 二倍频环流注入 高频注入 降低电容电压波动 

分 类 号：TM731[电气工程—电力系统及自动化]