Research And Application Of Fault Diagnosis Methods For Traction Power Supply Reflux System

The traction power supply return system is an important component of the traction power supply system,and its operation status is directly related to the safe and stable operation of the railway.In recent years,the rapid development of electrified railways has led to a continuous increase in traction backflow,leading to frequent failures in the traction power supply backflow system,which has caused serious harm to the safe and stable operation of the railway.To this end,research has been carried out on fault diagnosis methods for traction power return system,and an online traction return monitoring and fault diagnosis system has been designed and developed to monitor the operation status of the return system and achieve rapid diagnosis and location of the return system faults.Firstly,the fault diagnosis method of traction return current system under direct power supply mode is studied.By establishing an equivalent circuit for the traction power supply reflux system,the reflux distribution coefficient under normal conditions is calculated,and the locomotive is regarded as a moving excitation source.The changes in the reflux distribution coefficient of each circuit before and after the locomotive passes the fault point under various fault conditions of the reflux system are analyzed.It is found that the maximum change in the reflux distribution coefficient occurs when the locomotive passes the fault point.Based on this,a fault diagnosis method for the traction reflux system under the direct supply mode is proposed,The correctness of this diagnostic method is verified by establishing a direct supply traction reflux system model on the Matlab/Simulink simulation platform.Secondly,the fault diagnosis method of traction return current system with AT power supply mode is studied.By establishing an equivalent circuit for the AT traction power supply backflow system,the theoretical analysis of the changes in the backflow distribution coefficient between the substation and AT under normal and various fault conditions of the backflow system is conducted.The conclusion is drawn that the fault characteristics of the low-voltage backflow branch under AT mode are the same as those under direct supply mode,and the distribution coefficient decreases as a whole when the impedance increasing fault occurs on the negative feeder of the high-voltage backflow branch,Based on this,a fault diagnosis method for the AT mode traction reflux system is proposed.Finally,the correctness of the diagnosis method is verified by building a Matlab/Simulink simulation model for the AT mode traction reflux system.Finally,an online monitoring and fault diagnosis system for traction backflow is designed and developed.The backflow of each branch is sampled through a multi-channel current synchronous collection device.A diagnostic program is developed using Java language,which can quickly diagnose and locate the fault of the backflow system,and the application of the proposed fault diagnosis method for the backflow system is realized.The test results of the return current system of a direct supply traction substation show that the developed online monitoring and fault diagnosis system for traction return current can achieve real-time monitoring of all return currents and automatic judgment of the operating status of the return current system.At the same time,the difference between the monitored value of the return current distribution coefficient and the standard value is less than 2%.It is determined that the return current system of the test substation is in a normal state,and the test results are consistent with the actual situation,The correctness of the functions of the traction reflux online monitoring and fault diagnosis system is proved.