Fast Simulation of MMC-HVDC Systems Using A Generalized Equivalent Circuit Model of MMC

Due to its salient features, the modular multilevel converter (MMC) has become the most advanced power converter topology for high-voltage dc (HVDC) transmission. Modeling and MMCs plays an important role in analyzing and understanding performance of MMC-HVDC systems under various conditions. Unfortunately, the detailed switching model is time consuming and turns out to be infeasible when it comes to simulating large-scale MMC-embedded power systems. To improve the computational efficiency of time-domain simulations for such applications, this paper presents a generalized equivalent model for MMC based on various sub-module circuits and arm configurations. The proposed equivalent model can significantly accelerate the simulation of MMC-HVDC systems while keeping its internal dynamics under both the fault and normal operating conditions. The proposed model can also work with different types of control strategies. Simulation results based on PSCAD/EMTDC validate the effectiveness of the proposed model.