三次谐波注入应用于MMC-HVDC的研究

摘要

The full use of semi-conductor devices in the submodules is a major factor in practical use of MMC-HVDC (modular multi-level converter for high-voltage direct current). Therefore, this paper investigates the influence of the third harmonic injection on MMC-HVDC systems in steady state operation in terms of bridge-arm current intensity and converter valve loss: Firstly, this paper introduces mathematical model of MMC and expounds third harmonic injection and its application in MMC. Secondly, based on analytical cal-culation this paper analyzes the advantages of third harmonic injection in terms of bridge arm current and converter valve loss; aiming at several topologies, the paper analyzes and compares pros and cons of third harmonic injection. The calculation result shows that the third harmonic injection can evidently decrease the bridge arm current and lower the loss of converter valve, which is of great value for practical engineering ap-plication.%如何最大程度地利用子模块中的半导体器件，是实际使用MMC-HVDC(模块化多电平换流器的高压直流输电系统)中一个关键问题。针对这个问题，从桥臂电流的大小以及换流器阀损耗两方面，研究了稳态运行时三次谐波注入对MMC-HVDC的影响∶介绍了MMC的数学模型，并且详细分析了三次谐波注入技术及其在MMC中的应用；采用解析计算方法，从桥臂电流以及换流器阀损耗的角度，分析了三次谐波注入的优势；针对几种拓扑，分析比较了三次谐波注入技术的优劣。计算结果表明，在稳态运行时，注入三次谐波能够减小桥臂电流，减小换流器阀损耗，因此该方案具有一定的实际工程价值。