电网电压不对称下模块化多电平变流器控制策略  

Control Strategy of Modular Multilevel Converter Under Unbalanced Grid Voltage

作　　者：李妍姝 LI Yan-shu(Shanxi Datong University,Dalong 031009,China)

机构地区：[1]山西大同大学,机电工程学院,山西大同037009 [2]大连交通大学,机车车辆学院,辽宁大连116028

出　　处：《电力电子技术》2021年第11期97-100,共4页Power Electronics

基　　金：国家科技支撑计划(2015BAF20B02);山西省教育科学“1331工程”专项课题(ZX-18050)。

摘　　要：在模块化多电平变流器(MMC)系统中,交流侧电网不对称会导致MMC交流侧三相电流非正弦,有功、无功功率出现波动,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,首先建立不对称电网下MMC系统的数学模型,提出了一种基于微分的正负序分离及锁相方法;其次结合抑制负序电流和瞬时有功功率两种控制目标,给出了不同控制目标下的内环电流参考指令表达式;最后基于实时数字仿真系统(RTDS)建立了10 kV/10 MW MMC-高压直流输电(MMC-HVDC)实验系统,在电网不对称故障情况下针对两种控制目标进行了实验验证,实验结果充分验证了所提控制策略的有效性。In a modular multilevel converter(MMC)system,the grid asymmetry on AC side will cause problems like non-sinusoidal 3-phase current on AC side of MMC,fluctuation of active and reactive power and large fluctuation of double frequency current and voltage on DC side.In order to solve these problems,mathematical model of MMC system under unbalanced grid is established at first,and a differential-based positive and negative sequence separation and phase-lock method is proposed.Secondly,combining the two control objectives of suppressing negative sequence current and instantaneous active power,the inner loop current reference expressions under different control objectives are given.Finally,a 10 kV/10 MW MMC-high voltage DC(MMC-HVDC)experimental system is established based on real time digital simulation system(RTDS),then the experimental verification for two control objectives under unbalanced grid is carried out respectively,and the experimental results have verified the effectiveness of control strategy.

关 键 词：模块化多电平变流器 电网电压不对称 正负序分离 

分 类 号：TM46[电气工程—电器]