| At present,our country’s economy and society are developing rapidly.The subway has become one of the main means of transportation in the city due to its large carrying capacity,fast and convenient characteristics,and has played an indispensable role in the process of urbanization.In view of the frequent start and stop conditions of subway vehicles,the recovery and reuse of subway brake braking energy has become one of the current research hotspots.Supercapacitors are especially suitable for the working conditions of frequent start and stop of subway due to their advantages of high power and high current,fast charge and discharge,long service life and low pollution.Based on the relevant data of Shenzhen Metro Line 5,this paper applies the ground-mounted supercapacitor energy storage system to the 1500 V subway interval substation.Based on the modeling analysis of the subway brake braking energy and the selection and configuration of the supercapacitor energy storage system,the theory analysis and simulation of the energy storage control method using the supercapacitor energy storage device to match the subway operating conditions have been carried out.The main works are as follows:Modeling of subway braking energy feedback system.Build a subway power supply system with 24-pulse rectification output,analyze the dynamics of subway trains,and build a motor speed control model based on rotor flux directional current hysteresis vector control.The mathematical model is constructed based on the working principle of subway vehicle brakes,and the regenerative braking energy generated when the subway train is braked is obtained,which provides the basis for the subsequent recovery and utilization of regenerative braking energy.Supercapacitor energy storage system configuration.Based on the performance analysis of the supercapacitor,combined with the regenerative braking energy generated analysis of the supercapacitor,combined with the regenerative braking energy generated when the subway train is braked,the capacity and series-parallel combination of the supercapacitor energy storage system are configured.A three-phase interleaved parallel DC/DC converter and a supercapacitor group form a supercapacitor energy storage device,and two sets of supercapacitor energy storage devices form a supercapacitor energy storage system in an interval substation.Design of energy storage control system.Perform inter-group current balance control on the input terminals of the two groups of supercapacitor energy storage devices,and realize the inter-phase current balance control of three-phase interleaved parallel DC/DC converters in the group.On this basis,the charge and discharge voltage threshold and SOC limit value of the energy storage system were reasonably selected,and a double closed-loop control method based on linear auto disturbance rejection control was designed,combining the energy management strategy of stabilizing and maximizing the utilization rate of the energy storage device.It realizes the recovery and utilization of the regenerative braking energy of subway brakes,and achieves the purpose of saving energy and improving the voltage stability of the traction network bus. |
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