When distributed energy storage systems (DESS) in islanded ac microgrid are controlled by conventional P-f droop control, the state-of-charge (SOC) of DESS is unbalanced. In order to balance the SOC of DESS with different capacities, a distributed droop control is proposed in this paper. The SOC balancing in the process of DESS charging and discharging can be realized without frequency deviation by adding a SOC balancing factor to the conventional P-f droop control. The value of SOC balancing factor is 1 after SOC balancing, and the control algorithm changes to the conventional P-f droop control automatically. Since the droop coefficient of conventional droop control is usually very small, the frequency can be kept within the specified range (±1%). Besides, the SOC balancing speed can be adjusted by changing the droop coefficient. Finally, the simulation and experimental results in different conditions show the effectiveness of the proposed scheme.
吴青峰, 孙孝峰, 王雅楠, 徐德勋, 李昕. 基于分布式下垂控制的微电网分布式储能系统SOC平衡策略[J]. 电工技术学报, 2018, 33(6): 1247-1256.
Wu Qingfeng, Sun Xiaofeng, Wang Yanan, Xu Dexun, Li Xin. A Distributed Control Strategy for SOC Balancing of Distributed Energy Storage Systems in Microgrid. Transactions of China Electrotechnical Society, 2018, 33(6): 1247-1256.
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2018, Vol. 33 
