孤岛电网中多储能设备SOC一致性优化策略

Optimal State-of-charge Balancing Control for Paralleled Battery Energy Storage Devices in Islanded Microgrid

基于下垂控制策略的蓄电池储能管理方案被广泛应用于孤岛电网,但在放电过程中并联蓄电池储能设备相互间将出现电荷状态(State of Charge,SOC)差异,使某些储能设备提前退出运行,显著削弱了系统稳定性。针对上述问题,提出一种适用于多储能设备的SOC一致性控制策略,并进行优化。将SOC作为下垂控制器输入量,根据SOC实时调节储能设备的输出功率,使并联储能设备的SOC在放电过程中逐渐趋于一致,进而在孤岛电网频率偏移约束以及逆变器最大输出有功功率限制下对加速因子进行在线优化,显著减少了并联蓄电池储能设备间SOC最终差值,达到更佳的均衡效果。仿真与实验结果验证了SOC一致性优化控制策略理论分析的正确性和实现方案的有效性。

The droop controlled battery energy storage device（ BESD） becomes more and more commonplace to maintain the stability of the islanded power system. In discharging process,the state-of-charge（ SOC） error between different BESDs could force some BESDs to cease operation earlier than expectation,which eliminates the system stability. An optimal SOC balancing control for parallel BESDs in islanded microgrid is proposed in this paper to effectively suppress the SOC error. The SOC of the battery is employed in the droop controller to adjust the output active power of BESD in real-time,and thus decline the SOC error among parallel BESDs. In addition,to achieve better performance of SOC balancing under the constraints of inverter＇s maximum output power and islanded microgrid＇s deviation frequency,the accelerating factor is optimized online based on the state of operation in order to diminish the final difference among SOCs. The effectiveness of the control scheme is validated by simulation and experiment results.