Submodules Fault-Tolerant Control and Analysis of Modular Multilevel Converter with Integrated Battery Energy Storage System

In this paper, submodules fault-tolerant control and analysis of Modular multilevel converter(MMC) with integrated battery energy storage system(BESS) are performed under hot reserve. A capacitor control strategy based on the average of the capacitor voltages, which is suitable for both normal operation and submodules fault-tolerant operation is proposed. Besides, difference currents are controlled flowing internally to ensure that the system's external characteristics remain unchanged before and after submodules fault. Then the influence of submodules fault on the arm current is analyzed by Monte Carlo simulation, and the conclusion that the maximum and RMS of the arm current will not exceed 1.1 times of the value of normal operation when redundancy ratio equals to 10% is drawn. Finally, the correctness of the analysis and control strategies is verified by experiment and simulation.