基于电池多应力耦合衰退机理的新老储能单元并联协作优化策略研究

In view of such problems as a decrease of aging synchronization, an increase of controlling difficulty and a rise of operating cost of parallel energy storage units, which are introduced by phased construction of energy storage power station and incorporation of second-use batteries, this project intends to carry out the research on optimization strategy of power sharing among parallel energy storage units at different aging states based on modelling of batteries’ capacity-loss trajectories under coupling factors. Firstly, by characterizing the effect mechanisms of multi-stress coupling aging conditions on the evolution rates of loss of lithium inventory and loss of active material, a whole-life capacity-loss trajectory model of lithium-ion batteries suitable for energy storage scenarios is established. Then, based on this, an equivalent conversion relationship between the evolution rate of equivalent core physical quantity of each mechanism under time-varying dynamic stress and that under standard cyclic stress is constructed, and a cumulative recursive calculation method of battery capacity loss under time-varying coupling conditions is formed. Finally, on the basis of the established recursive method, the influence law of retirement synchronization of dynamic constraint curve of energy storage units on the aging decommissioning cost of parallel battery pack is analyzed, real-time power sharing principle with consideration of economy, flexibility and aging synchronicity is put forward, and multi-objective optimal operation strategy of parallel energy storage units at different aging states is formed. This project has great academic significance and application value for enriching the technical connotation of whole-life utilization of lithium-ion batteries, exploring the advanced optimization technology of energy storage systems, and promoting the development of new energy industry.

针对储能电站分期建设与梯次电池陆续并入，所引起的并联储能单元老化同步性下降、控制难度增大、运行成本增加等问题，本项目拟开展基于电池多应力耦合衰退机理的新老储能单元并联协作优化策略研究。首先，通过表征多应力耦合老化条件对可循环锂损失与活性材料损失机制演化速率的作用机理，建立适用于储能场景的锂离子电池全生命容量衰退轨迹模型。然后在此基础上，构建各机制等价核心物理量演化速率在时变动态应力与标准循环应力作用下的等效转换关系，形成时变耦合应力工况下的电池容量损失累积递推计算方法。最后基于所建立的递推算法，分析储能单元退役同步性动态约束曲线对并联工作组老化折损成本的影响规律，进而提出计及经济性、灵活性、老化同步性的实时功率分配原则，最终形成新老储能单元并联系统的多目标优化运行策略。该项目对于丰富锂离子电池全生命利用技术内涵，探索储能系统先进性运行技术，促进新能源产业发展具有重要的学术意义与应用价值。

随着大规模锂离子储能电站的分期建设与退役梯次电池的陆续并入，储能系统内各并联储能单元间的老化程度及衰退轨迹将呈现出明显的差异化趋势，并可能引发并联单元工作组乃至整体储能系统的同步性下降、控制难度增大、运行成本的增加等问题。如何利用先进的并联储能单元协同运行策略，通过对上层调度指令的实时优化分配，实现并联工作组在全生命周期内，整体运行成本的降低与工作寿命的延长，已成为大规模储能领域亟待解决的关键性问题之一。.为此，本项目开展了基于电池多应力耦合衰退机理的新老储能单元并联协作优化策略研究。首先，通过表征多应力耦合老化条件对可循环锂损失与活性材料损失机制演化速率的作用机理，建立了适用于储能场景的锂离子电池全生命容量衰退轨迹模型。通过电池在不同耦合老化条件下的验证实验表明，与现有模型相比，本模型在5%的容量损失率预测误差容限内，将容量损失预测模型的适用范围由容量损失率小于20%的阶段扩展至电池的整个生命周期。然后，在此基础上，构建了各机制等价核心物理量演化速率在时变动态应力与标准循环应力作用下的等效转换关系，形成了时变耦合应力工况下的电池容量损失累积递推计算方法。该方法使得对电池全生命老化成本的计算，可以被独立分解至每一次调度指令的分配过程中。最后，基于所建立的递推算法，分析储能单元退役同步性动态约束曲线对并联工作组老化折损成本的影响规律，进而提出了计及经济性、灵活性、老化同步性的实时功率分配原则，最终形成新老储能单元并联系统的多目标优化运行策略。通过对大规模储能电站的仿真分析，运行新策略的储能系统在采用传统调度策略的对比组寿命终止后，仍有近20%的成本剩余。该项目研究成果对于丰富锂离子电池全生命利用技术内涵，探索储能系统先进性运行技术，促进新能源产业发展具有重要的学术意义与应用价值。