MMC-BESS电池荷电状态三级均衡控制策略

基于模块化多电平变换器拓扑的电池储能系统(Modular Multilevel Monverter based Battery Energy Storage System, MMC-BESS)可以同时输出有功、无功功率,适用于中高压、大功率的新能源并网场合。为解决储能单元的差异导致其荷电状态(State of Charge, SOC)不均衡的问题,提出了一种电池SOC三级均衡控制策略。首先针对各相间SOC差异,通过控制桥臂环流直流分量改变每相功率,实现了各相SOC均衡。其次针对同相内上下桥臂SOC差异,通过控制桥臂环流基波分量改变上下桥臂功率,实现了每一相内上下桥臂SOC均衡。最后针对同一桥臂内子模块SOC差异,通过重构调制波改变子模块功率,实现了所有子模块SOC均衡。实验结果验证了该控制策略的有效性。

Three-level balancing control for battery state-of-charge based on MMC-BESS

The Modular Multilevel Converter Based Battery Energy Storage System (MMC-BESS) can output active and reactive power at the same time. This is suitable for new energy grid connection with medium-high voltage and high power occasions. In order to solve the problem of unbalanced State of Charge (SOC) caused by the difference of energy storage units, a three-level balance control strategy of battery SOC is proposed. First, in view of the SOC difference between the phases, SOC balance is realized by changing the power of each phase by controlling the DC component of the bridge arm circulating current. Then, for the SOC difference of upper and lower bridge arms in the same phase, the SOC balance is realized by changing the power of the upper and lower bridge arms through controlling the fundamental frequency component of the circulating current. Finally, for the SOC difference of the sub-modules in the same bridge arm, the SOC balance is achieved by changing the power of the sub-modules by reconstructing the modulation wave. Experimental results verify the effectiveness of the control strategy.This work is supported by the National Natural Science Foundation of China (No. 51807073).