Research On Energy Feedback Device In Metro System

The rapid development of urban subways has the advantages of large passenger capacity,fast running speed,low pollution,safety and punctuality.Its power consumption accounts for a gradual increase in the proportion of electricity used in the city.Therefore,the regenerative braking energy generated by its frequent braking is quite considerable.Reasonable recycling and utilization of this part of energy is of great significance in urban metro systems at home and abroad,and the research of inverter energy feedback scheme has great value.This thesis aims to develop energy feedback devices in subway systems,including the following:Firstly,the mathematical model of the energy feedback device is deduced,and its vector control strategy is derived according to the mathematical model of its two-phase rotating d-q coordinate system.The key current loop and voltage loop are introduced in detail,including the derivation of the transfer function and the tuning of the PI parameters.In addition,the key technologies of the system are simulated and experimentally analyzed,including adaptive grid voltage phase-locked loop technology,digital implementation of SVPWM modulation strategy and over-modulation processing,carrier phase shifting technology and islanding detection technology.Then,the main circuit topology of the energy feedback device and the selection and calculation of the main components,as well as the hardware framework of the control system are introduced.On this basis,the software design of the unit control system based on TI TMS320F28335 microprocessor is introduced in detail,including the introduction of microcontroller and programming environment,the design of main program,the design of main interrupt program,AC voltage and current sampling and calculation,PI regulator programming,first-order low-pass filter programming and IGBT overcurrent protection programming,etc.Finally,the simulation model of energy feedback device is built by MATLAB/Simulink,and the functions of the system are simulated and reproduced,such as starting feedback,grid voltage synchronization and total harmonic distortion rate of grid-connected current before and after carrier phase shift.It provides a good theoretical reference value for the development of prototypes.The prototype of the design of this thesis was tested by constructing the test platform,including the startup feedback performance,the power factor and the total harmonic distortion rate of the grid-connected current.The experimental results show that the prototype designed in this paper has basically realized the function,and has reached most of the technical indicators,meeting the initial needs of users.