Analysis Of Harmonic Current In High-speed Railway And Its Influence On Track Circuit

With the rapid development of high-speed railway and heavy haul railway in the recent years, locomotives of motor train unit are used widely. The motor train unit which adopts the different drive system from the locomotive of existing line not only highly improves tractive power, but also the distribution feature of harmonic wave changes so as to guarantee the safe signal system of train operation, and especially makes the electromagnetic environment of track circuit equipment more complicated. With the harmonic wave problems of high-speed railway becoming more and more serious, the fault cases due to the equipment of track circuit interfered by electric current of harmonic wave happen from time to time, which has a bad impact on the normal operation of high-speed railway. At present, research about the problems of harmonic wave of high-speed railway mainly lies on the influence happens to the supply system of railway tractive power resulting from the harmonic wave current, but the research on the harmonic wave interference of signal system is less. Therefore, it is urgent to conduct deep research on the feature of harmonic wave of high-speed railway, and put forward the limiting value of the harmonic wave current within signal working band to guarantee the railway circuit operates smoothly and stably.In that context, based on the analysis of the source of tractive harmonic wave current and the principle interfering railway circuit, we analyze the distribution feature of harmonic wave of steady state tractive current according to the reference standard CLC/TC50238-2:2010 which states the analysis method of harmonic wave in order to obtain the proportional distribution of harmonic wave current of steady state and changing rules. The main contents of this thesis are as follows:First, according to the systematic indicators and demands, the establishment of tractive harmonic wave test system is set up, which is able to collect and analyze data for the tractive harmonic wave. Check for the accuracy of date collected of test system has been performed to prove that the system can accurately measure harmonic wave current.Second, on the basis of data processing software of LabVIEW development platform, the outcome of data playback, time-domain and frequency-domain analysis of harmonic wave, feature analysis of harmonic wave distribution can be achieved and stored.Then, the test can be completed by using test system on the site of railway. The mass data collected can be processed, analyzed and recorded by using data processing software. Through the statistic analysis of processing results of steady state tractive current, we can obtain the distribution feature of harmonic wave in the signal working frequency band and non-frequency band.At last, according to the correlation between the harmonic wave proportion and total current, prediction model of harmonic wave proportion is established by using curve-fitting theory to different types of motor train unit locomotives.We have made a preliminary prediction of the situation of harmonic wave current under the condition of strong tractive current in the signal working frequency band. And we also put forward some suggestions that meets limiting value of compatible harmonic wave current for tractive power supply and track circuit compared with the standard CLC/TC50238-2:2010 and TB/T3073.