Study On Interference And Suppression Method Of Neutral Zone Harmonic In Track Circuit

With the rapid development of overloaded and high speed railway,the electrification interference problems have become increasingly prominent.The electromagnetic environment of track circuit equipments even more complicated.At the same time,such broken equipments cases due to the harmonic wave interference happened frequently.In recent years,Surveys show that when electric locomotive passes the track section with the phase zone,the railway signal equipment is more susceptible to interference.This article mainly studies the harmonic interference caused by the electric locomotive during the phase separation zone,and puts forward an effective solution combined with the railway condition.The mainly research work of this article includes:1.Collecting cases of harmonic interference exists in the Phase separation zone.By analyzing the superiority of the windowed FFT in terms of the accuracy of the traditional FFT,and the characteristics of the transient inrush current when the electric locomotive is closed by the split-And the method of dealing with the harmonic characteristic of the over temporal transient signal with windowed FFT method is verified.2.Referred to the method of dealing with harmonic data by European standard CLC/TC 50238-2:2015 and the system of dealing with harmonic data set up based on Lab View platform.3.Based on the harmonic analysis platform,the original data of the carrier frequency 1700Hz orbit is disturbed by a scene analysis and systematic processing.The results show that both the voltage signal and the current signal are both indoor and outdoor,Power frequency odd harmonic 1750Hz occupies a large proportion.So according to the basic characteristics of the track signal and the harmonic interference spectrum,it is obvious that the main factor to judge the harmonic interference is the frequency quasi-harmonic 1750Hz.4.According to the amplitude of railway carrier frequency 1700Hz signal and 1750Hz harmonic wavelength interruption,this article has formulated the declining index and proposed two methods to reduce harmonic wavelength interruption.One is to design a FIR digital band-pass filter on the base of FPGA.Based on the theoretical calculation and simulation,FIR digital filter could achieve declining index.But it has high order and long response time.Even because of the small interval of signal and interfering harmonic frequency,and the frequency shift signal have been attenuated,caused a low reliability.The other is collaborative optimization scheme of transmitter and actuator in track circuit.The results of modeling and calculation on matlab show that it could decrease 1750Hz harmonic wavelength without influencing shifting frequency signals.Although it does not achieve the declining index,there are some inhibitory effects,the reliability is high.In comprehensive consideration,we finally adopted the second method and applied it to the railway fault site.In this article,the method of harmonic interference analysis and the coordinated optimization of signal for interference are proposed,which is of great value to improve the track circuit of electrified railway.