基于改进下垂控制的并网级联型储能系统SOC均衡策略

并网级联型储能系统；P??下垂控制；电网同步；有功功率平衡；SOC均衡

SOC balancing strategy of a grid-connected cascaded-type energy storage system based on advanced droop control

There are imbalance problems in the State of Charge (SOC) of batteries in grid-connected cascaded-type battery energy storage systems. Thus an improved droop control considering SOC balancing strategy is proposed. Based on traditional droop control, this method introduces a distribution correction term by considering SOC real-time estimation information of each battery pack. Then the reference active power and reference voltage amplitude can be reasonably distributed according to the SOC information, and the SOC balancing of each module is achieved without affecting the normal power output as well as keeping synchronization with the grid. In this way, the SOC balancing speed can be adjusted by changing the correction coefficient. In addition, stability analysis of the system based on singular perturbation theory is carried out, and the design basis for control parameters is given. The simulation results under different conditions verify the correctness and validity of the proposed control strategy and the theoretical analysis.This work is supported by the Natural Science Foundation of Hunan Province (No. 2017JJ2348).