Comparison of Harmonic Linearization and Harmonic State Space Methods for Impedance Modeling of Modular Multilevel Converter

The impedance modeling of the modular multilevel converter (MMC) is the key for the resonance and stability analysis of MMC-based power systems. Especially, the internal dynamics of the MMC, which may have a great impact on the terminal characteristics of the MMC, need to be taken into account in the impedance modeling. To this end, two main methods have been reported in recent literatures to develop the MMC impedance models, i.e., harmonic linearization method and harmonic state space (HSS) method. So far, there is a lack of comparison between the two methods. Therefore, this paper presents a comparative study on the harmonic linearization and HSS methods in application of the MMC impedance modeling. The equivalence as well as the merits and demerits of these two methods are discussed.