Research On The Regenerative Braking Energy Feedback System Of Urban Rail Transit

The comfortable and fast urban rail transit facilitates our commuter journey and alleviates the tension of urban ground transportation.However,the energy generated by the frequent start and braking of the train is not fully utilized or even wasted,which deviates from the energy saving and environmental protection.How to recycle this part of energy,and how to cooperate with the power grid in the recycling process is a core problem faced by the rail transit power industry.This paper conducts relevant research on this problem,and its main research conclusions and results are as follows:The braking energy processing scheme of urban rail train mainly includes energy consumption type,energy storage type and feedback type.First,select the feedback type after comparative analysis.The reason is that not only the energy recycling,but also the low maintenance cost in the later stage,to meet the energy conservation and environmental protection and save economic costs,and the recycled energy back to the medium voltage AC network side has a higher energy reuse rate.Secondly,the theoretical calculation is carried out according to the relevant parameters of a city rail locomotive operation to verify that the regenerative braking energy generated by train braking is considerable and it is necessary to reuse this energy.Finally,the analysis and selection of energy feedback provide theoretical basis for the design of regenerative braking energy feedback device.The overall design of regenerative braking energy feedback device specifically includes main circuit design,design of control circuit and collaborative control design.The main circuit design is to formulate the electrical schematic diagram according to the actual operation situation and theoretical basis of a city rail transit.The relevant parameters of the main converter device,filter device and isolation transformer are set and the test operation data are analyzed.The control circuit design mainly includes the functional design of each circuit board,the communication circuit design required by the device,and the pulse width modulation(Pulse width modulation,PWM)drive circuit design of the core element insulated gate bipolar transistor(Insulated Gate Bipolar Transistor,IGBT)module.Then,through the established intelligent operation and maintenance platform,the collaborative control and intelligent control of the whole line regeneration energy feeding device are realized.Finally,by monitoring the regenerative braking energy feedback device during the train operation,the actual operation data collection and analysis,and verify that the device is well coordinated with the train operation and has good energy feedback effect.In order to reduce the AC harmonic content of the regenerative braking energy feedback device,the regenerative braking energy feedback control system is designed and studied.First,the three-phase three-level active midpoint clamp converter(Three-level Active Neutral Point Clamped Converter,ANPC)and its topology are analyzed.Establish the switch function and mathematical model.Secondly,using the double closed-loop control structure,scale integral adjustment controller(Proportional Integral Controller,PI controller is designed for voltage loop and current loop).Then the simulation model of the Simulink regenerative braking energy feedback control system is established.Through the analysis of the simulation results,the designed controller meets the requirements of the control system,which can give energy back and stabilize the DC network pressure.In order to reduce the output harmonic content and improve the power quality of the system,the scheme design of adding the proportional resonance controller(Proportional Resonant Controller,PR controller)in the current internal loop,realizing the unstatic tracking of sinusoidal quantity。It can be seen from the simulation results with less output wave harmonics and higher power quality under the PR controller.