基于MMC拓扑的混合型滤波器设计及其在LCC-HVDC中的应用

针对传统无源滤波器占地面积大、易与交流电网阻抗引发串并联谐振等固有问题,提出一种适用于基于电网换相换流器的高压直流输电(LCC-HVDC)系统交流侧滤波的混合型滤波器。该混合型滤波器的无源滤波部分与有源滤波部分串联后与电网并联,其中无源滤波部分为传统的双调谐滤波器,有源滤波部分基于模块化多电平换流器(MMC)拓扑结构。分析了有源滤波部分的输出电压控制增益、交流电网等效阻抗对混合型滤波器滤波性能的影响,利用根轨迹法确定了增益的取值范围。最后在Cigre模型的整流侧完成仿真验证。结果表明,该混合型滤波器能够减少传统无源滤波器的占地面积,具有良好的滤波效果及较强的鲁棒性,能实现换流站无功功率的全补偿。

Design of hybrid filter based on MMC topology and its application in LCC-HVDC

Aiming at the inherent defects of traditional passive filter, such as big ground occupation and series-parallel resonance easily caused with AC grid impedance, a hybrid filter that is suitable for AC side filtering of LCC-HVDC(Line Commutated Converter based High Voltage Direction Current) system is proposed. The passive filtering part of the hybrid filter is connected in series with the active filtering part, and then connected in parallel with the grid. The passive filtering part is the traditional double tuned filter. The active filtering part is based on MMC(Modular Multilevel Converter) topology. The influence of the output voltage control gain of the active filter part and the equivalent impedance of the AC grid on the filtering performance of the hybrid filter is analyzed. The value of the gain is determined by the root locus method. Finally, the simulation verification is completed on the rectification side of the Cigre model. The results show that the hybrid filter can reduce the ground occupation, has good filtering effect and strong robustness, and can fully compensate the reactive power of the converter station.