摘要
传统的基于网压或者人工智能算法的控制策略虽然可以使车载储能装置制动能量具有一定的回收效果,但是却存在忽略了储能元件自身充放电特性、模型建立复杂、难以求解最优策略的解析解等问题。为此,该文提出基于等效面积法的车载储能装置控制策略。在储能装置的充电阶段,为了保证最优的节能效果,以储能装置的功率作为状态变量,通过选取最优的初始电压和充电电流,使列车制动功率曲线与储能装置充电功率曲线所围面积最大。储能装置的放电阶段,在保证储能装置的放电截止电压在列车牵引结束时达到最优充电初始值的前提下,选取合适的放电电流使列车牵引功率曲线与储能装置放电功率曲线面积差的最大高度最小,此时车载储能装置的“填谷”效果最佳。该策略从列车的牵引制动特性出发,不仅充分考虑了储能元件的充放电特性,而且模型简单、计算量小、且易于求解得到最优控制策略的解析解,从而可以充分发挥储能装置的充放电能力。算例分析结果表明,相较于传统的基于网压的双环PI控制策略,所提的控制策略可以进一步提升储能装置的充放电量,节能效果显著。
Conventional control strategies of on-board energy storage systems(OESSs)based on catenary voltage or artificial intelligence algorithms can achieve a certain level of regenerative braking energy recovery.However,they ignore the charging and discharging characteristics of energy storage elements and fail to provide an explicit analytical solution to the corresponding control parameters due to the complicated model.On the other hand,according to the characteristics of the supercapacitor,its power is at odds with the amount of energy it can absorb.If the initial voltage of the supercapacitor is low,the energy it can absorb would be large while the charging power would be low,and vice versa.Therefore,it is an issue worth studying how to set a reasonable initial voltage and charging/discharging current to balance the power and absorbable energy of a supercapacitor so that the best regenerative braking energy recovery effect can be achieved.The OESS is charged when the urban rail train is braking and discharged when the train is in traction.The power profile of the train was divided into two parts in this paper:"braking"and"traction",and the charging and discharging processes of the OESS were studied,respectively.When the train was braking,the OESS should be charged as much as possible to ensure the optimal energysaving effect.By applying the area-equivalent principle,the problem of maximizing the charge of OESS could be transformed into a mathematical problem of maximizing the area enclosed by the braking power curve of the train and the power curve of the supercapacitor.When the initial voltage and charging current of the supercapacitor varied,the shape enclosed by the two power curves was also different.Therefore,the enclosed area with various shapes was modeled with respect to different initial voltages and charging currents.Finally,the optimal initial voltage and charging current corresponding to the largest enclosed area were picked out,and the energy-saving effect of the OESS was the best in this case.As for the discharging process,the design principle of the OESS discharge strategy was to ensure that the voltage of the supercapacitor at the end of the train traction reached the optimal initial voltage of the braking stage obtained above.According to the area-equivalent principle,this goal could be achieved by making the area enclosed by the two power curves equal to the discharged energy of the supercapacitor during train traction.Furthermore,to maximize the"valley-filling"effect of the OESS,the charging time of the OESS was set equal to the traction time of the train to obtain the optimal discharge current.In this way,the maximum height of the area difference between the train traction power curve and the supercapacitor power curve could be cut down;in other words,the peak power absorbed by the train from the traction network could be reduced.Finally,a case study was conducted based on the single-train operation scenario to verify the effectiveness of the proposed control strategy.The result shows that,compared with the traditional voltage-based double-loop PI control strategy,the control strategy proposed in this paper can further improve the charging and discharging capacity of OESS and thus have a more significant energy-saving effect.
作者
米佳雨
杨中平
钟志宏
林飞
邵一晨
Mi Jiayu;Yang Zhongping;Zhong Zhihong;Lin Fei;Shao Yichen(School of Electrical Engineering Beijing Jiaotong University,Beijing 100044 China)
出处
《电工技术学报》
北大核心
2025年第3期975-986,共12页
Transactions of China Electrotechnical Society
基金
国家重点研发计划资助项目(2022YFB4301203)。
关键词
城市轨道交通
车载储能装置
制动能量回收
控制策略
等效面积法
Urban rail transit
on-board energy storage system
regenerative braking energy recovery
energy management strategy
area-equivalent principle
