Multi-type Energy Storage System Operation Strategy Based on Grouping State of Charge Regulation

Renewable energy power output exhibits randomness and uncertainty. Energy storage systems (ESS) has been proved to be an effective means of mitigating the variability of renewable energy power output. Nevertheless, due to the limitation of ESS's cycling life, it needs to construct a rational operation strategy to enhance its efficiency. In this paper, a multitype energy storage system (MESS) composed of lithium-ion battery (LIB) and vanadium redox flow battery (VRB) is used to assist the photovoltaic (PV) in tracking the power scheduling, and the MESS operation strategy considering the VRB grouping state of charge (SOC) regulation is proposed. Firstly, the power allocation limits for MESS and the VRB grouping methodology are established using the allowable deviation ranges of PV's scheduled power. Secondly, the influence of VRB on the cycling life of LIB is considered in order to develop a strategy for VRB grouping SOC recovery and establish appropriate charging and discharging thresholds for VRB. Thirdly, a model for the operation of PV and energy storage system is established, and PV power tracking schedule and the cycling life of MESS are considered in this model. Finally, the proposed model is finally subjected to simulation using real PV data. The results demonstrate the feasibility and effectiveness of the proposed method.