南京西环网串联侧换流器谐波特征分析

摘要

分析了采用模块化多电平换流器(MMC)结构的统一潮流控制器(UPFC)的谐波特性,推导了MMC子模块电压波动与网侧输出电压谐波之间的关系.分析表明,电容电压的2次谐波波动频率与换流器输出电压的3次谐波分量密切相关.结合UPFC现场测试数据,分析对比UPFC运行前后串联线路的零序分量变化规律,线路中3次谐波分量大小可为串联变压器性能的评价提供参考依据.%The harmonic characteristics of unified power flow controller(UPFC) with multi-level modular converter(MMC) structure is analysed,the relationship between submodule capacitor voltage variation of MMC and the harmonic of grid side output voltage is deduced.The analysis indicates that second-harmonic variation frequency effects third-harmonic in MMC output voltage,which injected zero-sequence current to grid.The field-test data shows that third-harmonic generated when UPFC put into operation,and when UPFC shut down,the third-harmonic disappeared.The third-harmonic change rule can be used in assessment of series transformer.