Influencing Factors of Harmonic Coupling in Modular Multilevel Converter

The feature of the modular multilevel converter (MMC) may worse the power quality, due to the additional harmonics caused by the harmonic coupling between the grid and the dc bus. It is difficult to analyze the influencing factors of harmonic coupling in MMC, since harmonic coupling processes are complicated. In this article, the mechanism of harmonic coupling of the MMC is analyzed first, considering that harmonics exist in the grid and dc side. The influencing factors of harmonic coupling are analyzed based on the harmonic coupling. The reference for the filter and MMC design, and the evaluation of the harmonic pollution can be provided by the analysis in this article. The correctness of the influencing factors has been proved by simulation and experimental tests.