Study On Protection Method Against Adjacent Section Interference In Jointless Track Circuit

As the key equipment of the train control system,track circuit plays an important role in train occupy checking and the continuous information transmission from the ground to the vehicle.Among them,the tuning unit is the key equipment to realize the electrical separation in the jointless track circuit(JTC),and its fault will cause the signal of adjacent track circuit enter into its own section,and then form the corresponding adjacent section interference,which may lead to the degraded operation of the train and affect the efficiency of railway transportation.At present,the research on this interference is insufficient at home and abroad.Therefore,the following research works have been carried out in this paper:1.Based on transmission line theory,the model of adjacent section interference is established,and the influence on track circuits and cab signaling by adjacent section interference are analyzed.On this basis,a two-level protection strategy for fault diagnosis and ground protection is proposed.Aimed to analyze the adjacent section interference before and after the fault of different tuning units,the interference amplitude model of induced voltage of track circuit reader(TCR)in JTC shunted state,the interference amplitude model of the voltage on rail surface and the interference amplitude model of input signal at track circuit receiver in JTC idle state are established respectively.And on the basis of verifying the correctness of the corresponding model,the influence rule of the corresponding adjacent section interference is analyzed.And then a two-level protection strategy for taking fault diagnosis of tuning unit based on microcomputer monitoring system and setting ground protector is proposed.2.Based on learning vector quantization(LVQ)neural network,a fault diagnosis method of tuning unit is proposed and the corresponding diagnostic software is compiled.In view of the influence rules of tuning unit fault analyzed above,LVQ neural network is constructed and trained by taking the length of two adjacent track circuit sections,carrier frequency of track signal,voltage amplitude level of sending signal and the amplitude of receiving voltage at JTC receiver as input vectors.Verification results show that the diagnostic accuracy of this method is 99.3%,which can meet the actual needs of railway field.And the software for fault diagnosis of tuning unit is compiled,so as to realize the integration of the proposed fault diagnosis algorithm and railway signal microcomputer monitoring system.3.Based on the characteristics of series and parallel resonant circuit,the ground protector against the adjacent section interference is designed,and the effect verification and impact analysis are conducted.The design idea of replacing the designated position compensation capacitor with the adjacent section interference protector is proposed.This protector is equivalent to the original compensation capacitor for track circuit signal in its own section,while it performs the short circuit effect as series resonance for the signal from adjacent section,so as to achieve the protection effect of attenuating the interference signal to zero.In addition,the influence of the deterioration of protector,the effect of protector on transmission of track circuit signal,information receiving of cab signaling and fault diagnosis of tuning unit are analyzed.