Capacity Configuration And Control Strategy Of Urban Rail Ground Hybrid Energy Storage System Based On Train Operation Condition

With the accelerating development of urban rail transit,the sharp increase in energy consumption and safe operation of urban rail system have been widely concerned.Assembling battery/supercapacitor hybrid energy storage system in the urban rail traction power supply system can make full use of the regenerative braking energy of the train,reduce the peak power of the traction substation and improve the voltage fluctuation of the traction network.In addition,it can also be used as a standby power supply for emergency traction of the train when the traction power supply fails,which provides strong support for the consumption reduction and safe operation of the urban rail system.Firstly,this paper analyzes the structure of urban rail transit traction power supply system with hybrid energy storage system and the working principle and control method of hybrid energy storage system.The simulation model of urban rail transit traction system with ground battery/supercapacitor hybrid energy storage system is built.Taking the actual line data as an example,the influence of hybrid energy storage system capacity configuration on energy flow is analyzed,and the power allocation strategy of hybrid energy storage system is simulated and analyzed.It provides the basis for the capacity configuration and control strategy research of hybrid energy storage system.Secondly,considering the characteristics and cost differences of battery and supercapacitors in the hybrid energy storage system and their impacts on the traction power supply system of urban rail transit,this paper proposes a capacity allocation optimization method of ground battery / supercapacitor hybrid energy storage system suitable for urban rail transit from a global perspective.This method takes the energy saving rate,the reduction rate of peak power and the economic benefit rate as the objectives,and takes the engineering realization and the emergency traction of the whole line train as the constraints.Under the premise of ideal energy saving effect,the peak power of the substation can be greatly reduced,and a higher economic benefit rate can be obtained.The effectiveness of this method is verified by a practical example.Then,this paper proposes a full-time multi-mode control strategy of hybrid energy storage system based on train operation conditions.This method is aimed at the all-day operation of the hybrid energy storage system.In order to give full play to the role of the system,the power and energy of the system are optimally allocated between the two energy storage components at different time scales.Considering different capacity configurations and the full-time energy flow management of the whole network,different working modes are switched according to different train operation conditions.The charging and discharging sequence of the battery and the supercapacitor is dynamically adjusted to allocate the power ratio of the battery and the capacitor in real time.By controlling the SOC(State of Charge)of the energy storage component,the energy absorption and utilization of the regenerative braking are completed,and the peak power of the substation is minimized.The control strategy is verified by an actual example.Finally,a 1MW ground Li Ti O battery/supercapacitor hybrid energy storage system prototype is developed,and the high power charge and discharge test and system function verification test of the prototype are carried out.Finally,the proposed control strategy is verified on the actual line.The experimental results verify the feasibility and effectiveness of the proposed control strategy through the whole day energy saving effect and the reduction of the peak power of the substation.