Study On Adjacent Line Interference And Protection Of High-speed Railway Track Circuit

High-speed railways have the characteristics of high speed and high density and also develop rapidly in the direction of information and intelligence in China.With the increasing integration of electronic equipment in the signaling system,it is more and more sensitive to the harsh electromagnetic environment.In addition,it is easy to cause adjacent tracks interference problems under the scenes of multi-line parallel in sections,track circuit coding in stations,and low track-bed in tunnels,which may result in wrong decoding and display of signal,taking disadvantages on the safety and running efficiency of high-speed trains.Therefore,it is important to conduct in-depth research on the signal transmission and interline coupling mechanism of track circuits under the condition of high-speed railways at the theoretical level,to establish a comprehensive simulation model of adjacent lines interference,and to propose feasible measures of protection against interference.The main research contents of this thesis are as follows.(1)Combined with the characteristics and structure of a high-speed railway track circuit,the transmission mechanism of the Frequency Shift Keying(FSK)signal and the characteristics of cab signaling receiving information are analyzed.Considering the coupling path of adjacent line interference,the interference mechanism of spatial coupling such as capacitive and inductive,and conductive coupling through leakage of ballast resistance and transverse connection line is studied.And the influence of adjacent line interference on track circuit and cab signaling is analyzed.(2)Aiming at the transmission mechanism of FSK signal of high-speed railway track circuit and the coupling effect of adjacent tracks,the coupling interference model of four typical scenarios under balanced conditions,and the conductive coupling interference model through transverse connection lines under unbalanced conditions are established for the further parameter calculation.A circuit simulation based on Multisim and a finite element method electromagnetic simulation is carried out to verify the track circuit transmission and interference coupling process,respectively.The simulation results show that the spatial coupling of adjacent line interference is observably larger than that of conductive interference,and mutual inductance is the main factor causing adjacent line interference.(3)Based on the three elements of electromagnetic interference,combined with the simulation model and engineering practice,the protection strategies of adjacent line interference are proposed.One of the effective measures for interference source suppression is adjusting the voltage of the transmitter to bring the entrance current of the cab signal to the lower limit index.The maximum limit of parallel length in different distances between tracks and the carrier frequency is proposed to reduce coupling effectively from the perspective of the coupling path.A high impedance transformer can be used to effectively suppress the conduction coupling interference through the transverse connection line under the unbalance scenario.To improve the anti-interference performance of sensitive equipment,it is necessary to implement route cutting and double-end code transmitting.At the same time,the thresholds and suggested indexes of each parameter are given,which can provide a reference for engineering design and signaling maintenance.(4)An adjacent interference protection method based on multi-parameter cooperative optimization is proposed.The influence of several typical parameters on adjacent interference was considered comprehensively,and the Artificial Bee Colony(ABC)algorithm was used to realize the quantitative analysis and optimization of interference.Aiming at the working environment of a field adjacent line interference typical case,the field data and calculative model simulation results are compared,the influence of different factors on interference intensity is comprehensively analyzed,and the multi-parameter collaborative optimization intelligent algorithm is applied to realize the anti-interference configuration and evaluation of signaling system.After the optimization,the Signal-to-Interference Ratio(SIR)can be improved by 15.68 d B.Among them,after the optimization of parallel length,the improvement of SIR accounts for 69.15%,which is the main factor causing the up-gradation of the cab signal in this case.