Battery Fault Tolerance of Modular Multilevel Converter-Based Battery Energy Storage Systems with Redundant Submodules

In a modular multilevel converter (MMC) based battery energy storage system (BESS), a fault tolerant design ensures uninterrupted operation of the MMC when a given number of submodules (SMs) have faulty batteries or no batteries. This paper quantitatively investigates the fault tolerance improvement in MMC-based BESSs with different numbers of redundant SMs, which is commonly practiced to improve the fault tolerance in modular converter topologies. Simulation results are obtained to verify the proposed analysis. The presented analysis provides guidelines for designers to choose an appropriate number of redundant SMs to achieve a desired fault tolerance.