Average Modeling and Stability Analysis of Virtual Synchronous Generator Controlled Modular Multilevel Converters

Average modeling and stability analysis of virtual synchronous generator (VSG) controlled modular multilevel converters (MMC) have been discussed. Based on modular idea, the average model includes 4 modules: VSG control model, MMC main circuit model, phase-locked loop model and AC side network model. Small signal model is also derived from the averaged model. Furthermore, system dynamics and stability have been discussed through the proposed small signal model. Simulation results of three MMC models (the controlled source model, the presented average model, and the small signal model) are compared to verify the effectiveness of these presented models.