Research On The Super Capacitor Energy Storage System Of Urban Rail Transit

The urban rail transit has the characteristics of short distance,high density,high speed and so on.Train start and brake very frequently,the train needs a lot of energy in the start,leading to the DC traction network voltage drop;The train regenerates the brake to produce the massive energy,causes the direct current traction network voltage to rise,in the serious time also can cause the regenerative braking to invalidate.In order to solve this problem,adopted a new type of energy storage device-super capacitor energy storage device.Super capacitors with high power density,fast charge and discharge,long life and other advantages.The super capacitor energy storage system is used to release energy during the starting phase of the train,and the regenerative braking stage stores energy;So as to achieve the goal of stabilizing the voltage of DC traction network,preventing the failure of regenerative braking,and reaching the goal of saving energy.In this paper,the control strategy of DC traction network voltage and inductor current inner loop is used to control the charging and discharging of the super capacitor energy storage system.Through the super capacitor charge and discharge of a variety of simulation studies for the super capacitor energy storage system to provide the theoretical basis for optimal design.The improved bi-directional DC-DC converter is designed to eliminate the resonance of the system and realize the zero-voltage switch,which reduces the turn-off loss of the switch and improves the efficiency of the system as a whole.The simulation model is built in matlab/simulink,and the simulation results verify the superiority of the improved bi-directional DC-DC converter and the rationality of the design parameters.The transfer function is obtained by the state space averaging method,and the optimal coefficient of the current and voltage and the integral coefficient of the voltage are obtained by bode diagram analysis.In the matlab / simulink to build a super capacitor energy storage system and inverter system simulation model to simulate theactual operation of the train.Simulation results show that the super capacitor energy storage system can stabilize the voltage and control strategy of the DC traction network.The inverter grid-connected system can reverse the voltage of the traction network and reduce the volume of the super capacitor.Finally,the hardware and software of the super capacitor energy storage system based on DSP chip is designed,which provides a solution for the establishment of a small power experimental platform.