Steady-state analysis of voltages and currents in modular multilevel converter based on average model

Abstract

Modular multilevel converter (MMC) is being considered as the next generation converter among multilevel topologies and by introduction of MMC, a new era has opened to the field of medium- and high-voltage, high-power converters. Sizing the passive elements and design of the converter and its performance evaluation is thus of great importance for researchers in this area. The present paper performs a steady-state analysis of the modular multilevel converter (MMC) based on average model. The magnitudes and phase angles of current and voltage quantities are calculated. The equations are solved for different components of the circulating current and submodule voltage, and the resonance behavior in circulating current harmonics is investigated. Based on resonance behavior of circulating current harmonics, a guideline is given to choose the magnitude of submodule capacitance and arm inductance. A model is developed in MATLAB/Simulink environment in order to verify accuracy of the calculations done.