The harmonic coupling matrix model can provide effective support for the study of harmonic stability of lines and components in power system. However, for the modular multilevel converter (MMC) with complex internal structure, the matrix model in the existing research cannot describe the coupling relationship between harmonics or only discuss the coupling relationship of specific harmonics. Therefore, considering MMC switch function, the coupling relationship between specific harmonics of a particular number of converters can be described, but it is periodic time-varying in itself, and the advantage that HSS can stabilize the periodic time-varying model and describe the coupling relationship between all times of harmonics of various quantities at the same time, the combination of the two can build harmonic coupling matrix model, which can simultaneously describe the relationship between all times of harmonics of all electric quantities of AC and DC sides of MMC at the same time. Finally, the theoretical calculation results of MMC harmonic coupling matrix model with harmonic disturbance are compared with the simulation results of PSCAD electromagnetic simulation model, which proves the accuracy of the proposed model in describing MMC harmonic coupling characteristics.
