Enhanced modular multilevel converter based battery energy storage system

This paper proposes an enhanced modular multilevel converter based battery energy storage system (EMMC-BESS) for interfacing low voltage batteries to the medium or high voltage grids. Besides the distributed battery integration functionalities and the inherited advantages of traditional MMCs, EMMC-BESS also provides the DC fault handling capability. Based on analysis of operation principles, the control algorithms are developed for power control and the balancing of battery state of charge (SOC). Moreover, typical DC fault is taken into consideration for further analyzing the DC fault blocking mechanism. Feasibility of the proposed topology and the control strategies are verified by test results.