Research on Multi-port Power Electronic Transformer With Battery Energy Storage System

The extensive integration of renewable energy has brought forward higher requirements for the stability and controllability of distribution networks. Therefore, it is necessary to combine power electronic transformer (PET) with energy storage technology to build a new type of flexible interconnected distribution network. This paper proposed a multi-port PET with battery energy storage system (BESS) and designed control strategies for the proposed system. The system can flexibly adjust the power flow among multiple ports and maintain the stability of DC voltage. Besides, BESS can be used to adjust the frequency of the system adaptively to avoid the system frequency over-limit when the load fluctuation is too severe. In addition, when an open circuit fault occurs in one side of the power grid, BESS can also be used for short-term voltage support to ensure the stable operation of the critical load. The simulation results show the stability and flexibility of the proposed system, which proves the effectiveness of the proposed control strategy.