桥臂轮流导通换流器谐波特性

Harmonic characteristic of AAMC

分析了桥臂轮流导通换流器(AAMC)的交流谐波特性和直流谐波特性,并提出了谐波控制的方法。子模块电容电压的波动导致换流器输出交流电压、电流包含高次谐波,通过采用带有三角形绕组的换流变压器,AAMC输出的交流电压、电流将只含有6k±1次的谐波,其中最低次为5次谐波,更高次谐波将显著降低,通过优化选择子模块电容和换流电抗器可以将谐波控制在相关标准的范围内。采用提出的将2个交流侧电压相位相差30°的AAMC阀组在直流侧进行串联的方案,直流侧电压、电流将只含有12k次谐波,谐波幅值将只有非串联方案的1/4,直流侧平波电抗器的取值降低为非串联方案的1/8。PSCAD/EMTDC仿真验证了谐波特性分析和谐波抑制措施的有效性。

The AC/DC harmonic characteristic of AAMC（Alternate Arm Multilevel Converter） is analyzed and the methods of AC/DC harmonic suppression are introduced. The capacitor voltage fluctuation of sub-module induces the high-order harmonics in its AC-side voltage and current outputs. For the AAMC applying converter transformer with delta windings,its AC-side voltage and current outputs contain only 6k±1 order harmonics,among which,the 5th harmonic is the lowest and the higher order harmonics are significantly weak. Its harmonics can be controlled by the optimal selection of sub-module capacitor and converter reactor to meet the requirements of relevant standards. A dual-AAMC scheme is proposed：two AAMCs with 30% phase difference between them at the AC side are connected in series at the DC side. Its DC-side voltage and current contain only 12k order harmonics,its DC harmonic amplitude is 1/4 of that of single AAMC scheme,and its DC-side smoothing reactor is 1/8 of that of single AAMC scheme. The effectiveness of the introduced harmonic characteristic analysis and harmonic suppression methods are verified by PSCAD/EMTDC simulation.