Research On Control Technology Of Rail Potential In Urban Rail Transit System

With city planning becomes more sophisticated,China’s rail transit system has developed rapidly.Generally,the DC traction power supply rail transit system uses steel rails for reflow.During the reflow process,there are problems of excessive rail potential and stray current leakage.The traditional solution is to use an over-voltage protection device to suppress the rise of the rail potential,and a drain cabinet to control stray current leakage.The two are independently controlled and affect each other.This article takes the rail potential as the research object,uses electronic load instead of OVPD,suppresses the rise of stray current while managing the rail potential,reduces the number of drain cabinet inputs,reduces the impact of the drain cabinet on the rail potential,and realizes Comprehensive treatment of stray current.Firstly,this article introduces the DC traction reflux system.According to the structure of the reflux system,a three-layer discrete model of "rail-drain network-earth" is established.Through analysis method,the distribution rules of rail potential and stray current are obtained,and the parameters of the reflux system are analyzed to obtain the main influencing factors of rail potential and stray current.At the same time,OVPD and drain cabinet devices are added to the discrete model to analyze the problems in the protection process of OVPD and drain cabinet.Secondly,the influence of variable resistance on the rail potential and stray current is analyzed,and the electronic load device is applied to the DC traction power supply rail transit system.By changing the equivalent resistance of the electronic load,the stray current is shunted to achieve the purpose of adjusting the rail potential.this article introduces the topological structure and working principle of the electronic load,and study the soft switching characteristics of the electronic load to improve the power density of the electronic load.According to the working mode of the electronic load,a variable step size disturbance control link is added on the basis of the traditional voltage and current double closed-loop control system to form a three closed-loop control system,and the design process of each loop is given.Finally,the electronic load device is added to the simulation model of DC traction reflux system.Through simulation analysis,the rationality and effectiveness of the three closed-loop control strategy are verified.At the same time,the feasibility of the electronic load in the process of rail potential management is also verified.The purpose of source voltage control.Through the simulation comparison of OVPD,drain cabinet and electronic load device,the superiority of electronic load in the process of rail potential management is verified.This paper has 86 figures,3 tables,and 69 references.