基于模块化多电平变流器的电池储能系统荷电状态均衡控制策略

State-of-Charge Balancing Control Strategy for Battery Energy Storage System Based on Modular Multi-Level Converter

基于模块化多电平变流器(modular multi-level converter,MMC)的电池储能系统(battery energy storage system,BESS)适用于中高压交直流混合电网,有助于解决可再生能源大规模并网问题。针对电池容量利用率问题,该文分析了MMC-BESS中各端电源功率传递关系,提出了一种电池荷电状态(state of charge,SOC)均衡控制策略,通过三级均衡控制,实现相间、上下桥臂间、桥臂内子模块间电池模块的SOC均衡。同时为提高系统运行的可靠性,研究了故障容错运行工况下的SOC均衡控制策略。最后通过仿真和实验验证了所提控制策略的有效性。

Battery energy storage system （BESS） based on modular multi-level converter （MMC）, contributing to grid-connection of renewable energy resource, is applicable to medium and high voltage hybrid AC-DC power grid. For the problem of battery capacity utilization efficiency, this paper analyzes power flow characteristics among all sources within MMC-BESS, and proposes a state-of-charge （SOC） balancing control strategy. SOC among phase legs, upper and lower arms, and sub-modules within the same arm is balanced with this 3-level control scheme. In order to improve system reliability, SOC balancing control scheme in case of sub-module fault is studied. Finally, simulation and experiment results verify feasibility of the proposed control strategy.