考虑电池SOC一致性的城轨交通MHESS功率分配策略

MHESS power allocation strategy for urban rail transit considering battery SOC consistency

在城市轨道交通中,通常采用多混合储能系统(MHESS)来解决列车在牵引和制动过程中所引起的牵引网络电压波动问题。该系统由超级电容器和锂电池组成,旨在平滑功率波动,实现“削峰填谷”。考虑到MHESS多个混合储能系统之间可能存在初始状态不一致的情况,提出一种考虑电池SOC一致性的RBF-PID控制策略,用于兼顾直流稳压特性以及电池储能系统寿命保护最优。由列车运行速度需求得到牵引功率需求,采用滑动平均滤波(MAF)算法将高频功率指令分配给超级电容,低频功率指令分配给电池与牵引网。进一步地,考虑到混合储能系统间初始状态不一致情况下的电池寿命保护问题,通过合理设计功率分配切换规则,在初始SOC较低电池的传统电压外环控制中引入基于电池SOC一致性的RBF-PID控制,合理控制电池的充放电电流,防止过冲、过放现象,从而延长电池寿命。为验证所提控制策略的有效性,使用Matlab/Simulink仿真软件进行仿真验证。实验结果表明,所提方法能够降低初始SOC较低电池的放电深度,有效保护储能元件。

Multi-hybrid energy storage systems(MHESS) are commonly used in urban railways to solve the problem of voltage fluctuations in the traction network caused by trains during traction and braking.The MHESS is composed of ultracapacitors and lithium batteries to smooth the power fluctuations and achieve "peak shaving and valley filling".Considering the possible inconsistency of the initial state between MHESS,an RBF-PID control strategy considering the consistency of the battery SOC is proposed,which is used to take into account the optimal DC voltage regulation characteristics as well as the lifetime protection of the battery energy storage system.The traction power demand is obtained from the train speed requirement,and the sliding average filtering algorithm(MAF) is used to allocate high-frequency power commands to supercapacitors and lowfrequency power commands to batteries and traction networks.Considering the issue of battery life protection in the case of initial state inconsistency between hybrid energy storage systems,a reasonable power allocation switching rule is designed to introduce RBF-PID control based on considering battery SOC consistency into the traditional voltage outer loop control of batteries with low initial SOC,to reasonably control the charging and discharging current of the battery,prevent overshoot and overdischarge,and extend the battery life.In order to verify the effectiveness of the proposed control strategy,Matlab/Simulink simulation software is used to carry out simulation verification,and the experimental results show that the proposed method can reduce the depth of discharge of the battery with a lower initial SOC,and effectively protect the energy storage components.