An Accurate and Fast Device-Level Real-Time Simulation of Modular Multi-Level Converter

Due to the massive research attention of modular multi-level converter (MMC)-based power conversion in the high- voltage and medium-voltage applications, there have been great demands in rapid validation of its control and protection strategies. Real-time simulation is an eligible choice that can fulfill a fast, safe and low-cost validation in the early-stage development of the MMCs. However, the performance of the MMC real-time simulation relies on both the modeling accuracy and the simulation speed, which can be very cumbersome to meet simultaneously due to the enormous switches in the converter. In order to improve the simulation accuracy while retaining computing efficiency, in this paper, a novel device-level real-time simulation approach is proposed for MMC. By using the efficient network decoupling techniques and piecewise linear transient switch models, the nonlinear switching transient can be effectively integrated into the MMC real-time simulation. A three-phase five- level MMC is used as a case study and simulated in the National Instrument FlexRIO FPGA module. A 100 ns real-time simulation time-step is realized. The simulation results have shown a very good agreement with the results of Saber simulation tool. Moreover, by implementing the software-in-the-loop real-time simulation, the effectiveness of the proposed approach is validated.