A Fast Electromagnetic Transient Modeling for Modular Multilevel Converter

When the number of sub-modules (SMs) in modular multilevel converter (MMC) is large, the simulation speed usually slows down significantly. In this paper, we propose a fast electromagnetic transient (EMT) modeling to solve this problem. In this paper, the equivalent MMC model is derived based on Thevein theorem, on the basis of which, control strategy is designed. Nearest Level Modulation (NLM) is selected as modulation strategy of MMC. Output current and circulating current are selected as the controlled variables of MMC closed-loop control. In this paper, after constructing the EMT model, simulation tests are conducted under three operation conditions in MATLAB/Simulink software to verify the feasibility of proposed model. It can be drawn that compared with original circuit, the proposed model accelerates the simulation speed of MMC and performs excellently in output current tracking and SM capacitor voltage balance.