Wind power output shows obvious fluctuations characteristics, and direct grid-connection will bring great challenges to the safe and stable operation of power system. This paper adopts the dual-battery energy storage operation mode which performs chargedischarge tasks separately based on the consideration of the effect of discharge depth and frequent chargedischarge conversion on battery life and energy utilization. In addition, this paper proposes chargedischarge operational stability index for characterizing the operation of DBESS, according to the real-time operating conditions of the energy storage system and wind power fluctuations. In order to solve the extreme operation problems caused by the unbalance of charge and discharge energy during the long-term operation of the dual-battery energy storage system, this paper uses the two proposed indicators as input, and presents a control strategy to adaptively fine-tune the first-order low-pass filtering time constant. Purpose of the above work is to change the battery throughput power in real time and optimize the state of charge of the two battery packs. The effectiveness of the proposed control strategy is verified from two aspects: optimization control effect on SOC and power fluctuations smoothing effect using MATLAB/Simulink software.
Keywords DOD, DBESS, status assessment indicator, unbalanced charge and discharge energy; control strategy