Efficient Simulation Method for Modular Multilevel Converter with Embedded Super Capacitor Energy Storage System

The numerous switching devices and extensive simulation scale of modular multilevel converter with embedded super capacitor energy storage system (MMC-SCES) pose a great challenge to the efficiency of electromagnetic transient simulation. To address this issue, an efficient MMC-SCES electro-magnetic transient simulation method based on the Thevenin equivalent circuit is proposed in this paper. The method employs a nested fast and simultaneous solutions approach to model MMC-SCES, which not only significantly reduces simulation time and maintains simulation accuracy, but also preserves all dynamic variables of the converter. A double-ended MMC-SCES simulation system is built to validate the proposed efficient simulation method. The results show that compared with the simulation method based on the average value model (AVM), the proposed efficient simulation method has higher accuracy and efficiency, which can fit the dynamic variables inside submodules.