Protection Scheme Design Of Hybrid Traction Power Supply System

In recent years,the rapid development of urban rail transit construction in China has greatly alleviated the problem of urban traffic congestion.However,with the rapid development of the city and the increase of passenger flow,the distance between stations is becoming shorter and shorter,and the frequency of train departure is becoming higher and higher,which leads to frequent train braking,resulting in a huge waste of regenerative braking energy,the hybrid traction power supply system including energy recovery device effectively solves this problem.Based on the "13th Five Year Plan" national key research and development task "Research and Application Demonstration of Key Technologies of Traction Power Supply System of Functional Composite Urban Rail Transit",according to the actual needs of scientific research and engineering projects,this paper designs the protection scheme of hybrid traction power supply system of Urban Rail Transit.Hybrid traction power supply system is very different from traditional traction power supply system in terms of structure topology,function,control method,voltage characteristics,etc.Therefore,this paper first studies the short-circuit transient and steady-state characteristics of AC and DC sides of energy recovery device,then analyzes the short-circuit characteristics of hybrid traction power supply system,and carries out short-circuit simulation for hybrid system,through comparing with the traditional power supply system’s simulation results,the new requirements of the hybrid system short-circuit protection scheme design are obtained.Secondly,according to the problem of short-circuit and over-current on the DC side of the energy recovery device,three current limiting methods are proposed,which are parallel bidirectional thyristor on the AC side of the energy recovery device,series resistance current limiting circuit on the DC side and series inductance current limiting circuit on the DC side.The basic principles of three current limiting methods are introduced respectively.The current limiting effects of three current limiting methods are compared through simulation,and the inductance current limiting is finally determined The short circuit characteristics of hybrid power supply system after current limiting are analyzed.In addition,according to its own characteristics,the protection method is designed,the AC protection and DC protection action logic are explained,and the protection methods and setting principles set in the AC incoming cabinet,energy recovery device’s low-voltage cabinet,DC incoming cabinet and DC feeder cabinet are designed and explained.Finally,the corresponding parameters in the protection scheme of hybrid traction power supply system are determined based on the system parameters and practical engineering experience,and the action logic and setting parameters of the protection scheme in this paper are simulated in the MATLAB/Sinmulink simulation software to verify the feasibility of the protection scheme.75 figures,4 tables and 45 references.