计及电池寿命的储能系统参与二次调频功率分配策略

Power distribution strategy of energy storage system auxiliary secondaryfrequency regulation considering battery life

储能系统辅助火电机组二次调频具有响应速度快、跟踪精度高等优点,但功率分配不当会加速电池寿命衰减,导致运行成本增加,经济效益下降。如何制定合理的储能功率分配策略,在确保调频性能的同时延长电池寿命并提高经济效益,已成为亟待解决的重要问题。首先基于二阶RC等效电路建立储能锂电池的数学模型,采用限定记忆最小二乘递推算法辨识模型参数;随后,在火储联合调频模型的基础上,对基于比例、差额和频率的3种功率分配策略进行了仿真分析;最后,根据江苏某660 MW火电机组的实际运行数据,重点分析了不同策略对系统调频性能、电池寿命及经济性的影响。结果表明,比例分配策略的调频效果最差,且会加速电池寿命衰减;差额分配策略在调频性能上表现优异,但对电池寿命的改善有限;频率分配策略能够有效降低电池更换频率,可提高整体经济效益。总体而言,频率分配策略不仅可提高系统的调频能力,还能最大限度延长电池寿命并优化经济效益,在储能系统辅助火电机组二次调频中具有显著的应用优势。

Secondary frequency regulation of thermal power units assisted by energy storage systems has the advantages of fast response speed and high tracking accuracy.However,improper power allocation can accelerate battery life degradation,resulting in increased operating cost and reduced economic benefit.Therefore,how to formulate a reasonable energy storage power allocation strategy to ensure frequency regulation performance while extending battery life and improving economic benefits has become a key issue that needs to be solved urgently.A mathematical model of energy storage lithium battery based on the second-order RC equivalent circuit was established firstly,and the limited memory least squares recursive algorithm to identify the model parameters was then employed.Subsequently,three power allocation strategies such as proportion,difference and frequency were simulated and analyzed based on the joint frequency regulation model of thermal storage.Finally,with the actual operational data from a 660 MW thermal power unit in Jiangsu,the effects of different strategies on system frequency regulation performance,battery life and economy were analyzed.The obtained results indicate that the proportion allocation strategy has the worst frequency regulation effect and accelerates the battery life decay.The difference allocation strategy performs well in frequency regulation performance but has limited effect on improving battery life.The frequency allocation strategy can effectively reduce the battery replacement frequency and thus improve the overall economic benefit.Generally,the frequency allocation strategy can not only improve the frequency regulation capability,but also maximize the battery life with optimized economic benefit,demonstrating significant application advantages in the secondary frequency regulation assisted by the energy storage systems.