State of Health Equalization Strategy for Retired Battery Based Energy Storage System

The safety of battery is of great importance in retired battery based energy storage system (ESS). When the state-of-health (SOH) of battery reaches the lower limit, the battery should be replaced to prevent accidents. In the energy storage power station, all the batteries are expected to be replaced at the same time so that the repair time and the maintenance cost can be reduced. This paper proposes a coordination strategy to equalize SOH among energy storage units and relieve inconsistency of batteries. Firstly, based on lithium-ion battery life cycle model, a method for SOH equalization control is derived. Secondly, an optimization model is constructed for the coordinated control in energy storage power station. Finally, the simulation shows the effect of the coordinated control strategy in this paper. This strategy can be applied to the energy management in retired battery energy storage power station for on-site control.