在孤岛直流微电网中,不同容量的分布式储能单元(DESU)之间存在荷电状态(SOC)均衡速度慢的问题,为此,提出一种考虑容量差异的分布式储能单元快速SOC均衡策略.首先,SOC均衡器通过幂函数构造下垂系数与SOC之间的关系,选取合适的均衡调节系数可实现下垂系数的自适应控制,加快SOC均衡速度.其次,在虚拟压降均衡器作用下,仅需简单调整比例积分控制器即可消除线路阻抗对电流精确分配的影响,提高电流分配精度.再次,通过系统稳定性分析,确定该策略控制参数的选取范围.最后,搭建直流微电网硬件在环实验平台,通过与现有文献对比和对不同工况下实验结果进行分析,证实所提控制策略不仅提高了SOC均衡速度,还实现了母线电压的快速恢复.

In an islanded DC microgrid, there is a problem of slow state of charge (SOC) equalization between distributed energy storage units (DESUs) with different capacities. To address this issue, a fast SOC equalization strategy for DESUs, which accounts for capacity differences, is proposed. First, the SOC equalizer constructs a relationship between the droop coefficient and SOC using a power function. By selecting appropriate equalization adjustment coefficients, the droop coefficient can be adaptively controlled, thereby accelerating SOC equalization. Then, the virtual droop equalizer is introduced to mitigate the impact of line impedance on current distribution accuracy by simply adjusting the PI controller, which improves the precision of current distribution. Additionly, the selection range of control parameters for this strategy is determined by using a system stability analysis. Finally, a DC microgrid hardware-in-the-loop experimental platform is developed. The experimental results, compared with those from existing literature under various operating conditions, demonstrate that the proposed control strategy improves the speed of SOC equalization and realizes the rapid recovery of bus voltage.