Power Allocation Strategy for Battery Energy Storage System Based on Cluster Switching

Battery energy storage system (BESS) plays an important role in the grid-scale application due to its fast response and flexible adjustment. Energy loss and inconsistency of the battery will degrade the operating efficiency of BESS in the process of power allocation. BESS usually consists of many energy storage units, which are made up of parallel battery clusters with a cell-pack-cluster hierarchical structure. This article presents a power allocation strategy based on cluster switching to relieve the stated problem in two levels. Cluster switching is identified as a new control approach to eliminating the imbalanced state of charge (SOC) in the cluster level. In the unit level, an optimization model is constructed for power allocation, where the objective function consists of two aspects: minimizing battery energy loss and maximizing SOC consistency. Finally, the effectiveness of the power allocation strategy for BESS in peak shaving and frequency regulation is validated by simulation and scaled-down experiment. The results prove that the power allocation strategy can reduce the battery energy loss and prevent from overcharging/overdischarging to extend the battery lifetime.