模块化多电平变换器的环流谐波抑制策略

Circulating Harmonics Suppression Method for Modular Multilevel Converter

在考虑子模块电压扰动的基础上,提出模块化多电平变换器(MMC)环流的等效控制模型,并在传统比例-积分环流控制器中加入谐振环节来有效抑制环路中的电压谐波扰动项,对环流中的低次谐波起到较好的衰减作用。为了获得更优的抑制效果,将重复控制引入到环流控制中,对扰动项中的各阶次都进行了很好的抑制,相比于多谐振控制的指定阶次抑制方法,重复控制策略形式更加简单、抑制效果更好。最后,对提出的多谐振抑制策略和重复控制策略进行了实验验证。

In this paper, an improved circulating current control model for modular multilevel converter （MMC） is proposed with the consideration of the submodule capacitor voltage disturbances. Then the resonant controller is utilized in company with the conventional proportional-integral controller to suppress the circulating harmonics. For better eliminating results, the repetitive controller is also proposed to suppress all orders of harmonics within the voltage disturbance. The proposed repetitive-based control strategy has simple forms and better results compared with the multi-resonant control, which only applies to the specified orders. Finally, the proposed multi-resonant and repetitive-based circulating control methods are validated by the experimental results.