Research Of Regenerative Braking Energy Utilization In Urban Rail Transit

When the urban rail transit train is in the braking condition,the traction motor of the train changes from the motor state to the generator state.At this time,the electric energy flows from the traction motor to the DC traction grid.This situation will lead to the following problems:(1)DC traction grid voltage rise high,endangering driving safety;(2)the working voltage of other electrical equipment in the traction grid is increased,and the service life of the device is shortened;(3)energy is wasted.In this thesis,we design a system for regenerative braking energy treatment of subway trains for the above problems.The system effectively avoids the above situation,and can reuse the regenerative braking energy generated by the subway train to reduce the traction grid voltage to ensure the stability of the power grid.The work of this thesis is summarized as follows:(1)In this thesis,we research the development status of regenerative braking energy processing technology for subway trains,at the same time,analyze the generation mechanism of train regenerative braking energy,then propose an inverter-resistive hybrid regenerative braking energy processing system.(2)Taking the B2 train of Metro Line 2 in a city in western China as an example,we calculate the energy generated by the single regenerative braking.Then,model the 24-pulse rectifier unit in the subway train power supply system and propose a control system for three-phase asynchronous traction motor.The control system of the AC asynchronous traction motor.Secondly,the space voltage vector control,Clark and Park coordinate transformation,and rotor flux linkage observation module are modeled and analyzed in this system.Finally,the space voltage vector control strategy is proposed under the control theory of asynchronous traction motor,and the train electric drive system is proposed.The braking conditions are simulated.(3)The inverter feedback regenerative braking device is designed,including inverter grid-connected control strategy,main circuit model design,IGBT parameter design and filter parameter design.The inverter regenerative braking energy processing system is modeled and simulated,and the shortcomings of the inverter feedback system are obtained through the simulation results.(4)The filtering schemes are analyzed.The active damping filter and passive damping filter are modeled and simulated.According to the simulation results,the filtering method is LCL active damping filter.(5)Use the Matlab/Simulink software to calculate and model the resistance energy-consuming braking system,and analyze the advantages and disadvantages of the resistor energy consumption type by simulation results.On this basis,we model the inverter-resistance hybrid regenerative braking energy processing system,and simulate the train braking condition in the system model,then compare the simulation results with the resistance energy-consuming braking simulation results.The simulation results confirm that the hybrid design can quickly reduce and stabilize the traction network voltage during train braking,and greatly improve the internal resistance heating problem of the tunnel.At the same time,the DC traction network energy is inverted into three-phase AC power and reused,which increases the regenerative braking energy utilization.