The Research Of Arc Conductive Noise In Pantograph-catenary System

Pantograph-catenary system is an important component of the power supply system in the electrified railway traction, the train get power from the sliding contact between the pantograph slide and catenary wires. In the train running process, due to the catenary wire irregularity and the catenary vibration role of various factors, the slide and contact wire will produce instantaneous separation, as the speed increases, resulting the contact loss rate in pantograph system increased dramatically, so the contact loss arc produced. In the pantograph-catenary system, the contact loss arc will release enormous energy, eroding the contact wire and slide, the high-frequency harmonic component that its over-voltage generated will cause interference and influence to the train electrical equipments, precision measuring instruments and relay protection devices, will bring serious threat to the safe operation of the electric locomotives and power supply system. Therefore researching the mechanism that the pantograph-catenary arc produced and it's harmonic characteristic have an important theoretical significance to the pantograph-catenary system.In this paper, using pantograph-catenary arc simulation system device, simulating the pantograph-catenary contact loss arc produce arc.MATLAB simulation model is established based on the equivalent circuit of the traction power supply system, set the start time to simulate the produce of the contact loss arc,and get the waveform of the contact loss arc voltage and catenary voltage. The simulation results show that when contact loss occurs, the arc voltage instantaneous distortion, the instantaneous voltage approach 2 times of the nominal voltage.Series of oscillation was produced when the catenary voltage passed zero.The arc voltage and contact line voltage distortion is more obvious after joining the model of electric locomotive, and more intense oscillations. After add the bypass capacitor in the primary side of locomotive transformer, there's a significantly inhibit effect to the transient overvoltage of contact loss arc. The longer the contact loss time is, the more unstable of the catenary system, the contact loss arc voltage contains a large number of irregular Inter harmonics and high amplitude harmonic component, which causes serious damage to electric locomotive and catenary system, and not conducive to the safe operation of electric locomotives. After three tiers decomposition to the contact loss arc voltage signal by using the db10 wavelet transform method, low frequency part of the waveform is very close to the sine wave, high frequency part of harmonic components have been effectively separated.By studying the influence that the speed and current to the pantograph-catenary arc harmonic characteristics, found that the arc exists abundant odd harmonic and even harmonic.The fundamental component of contact loss arc voltage increases along with the accelerate of running speed and contact current. The arc voltage's even harmonic is on the rise with the increase of speed, and the influence to the odd harmonics is not obvious. The arc voltage's even harmonic content is much smaller than the odd harmonic under different contact currents.The arc voltage and current's two times, three times harmonic content is large, and the other harmonics decayed rapidly.