Calculation Of The Impedance Parameter Matrix Of The Impedance Of Traction Network

With the booming development of China's high-speed railways,it has become an indispensable means of transportation for Chinese citizens and one of the pillars for national economy.However,due to the long-time exposure to natural environment,short-circuit faults may occur at high-speed railways from time to time.Thus,the fast and accurate positioning of faults is the basis for ensuring the safe and stable operation of high-speed railways.Traveling wave fault distance measuring technology is a promising method of distance measurement with both accuracy and rapidity.But due to the dispersion of traveling wave,the wave speed is hard to calculate which may affect the measurement accuracy.The traveling wave dispersion is mainly caused by the fact that the impedance is a function of the current frequency which is induced by the skin effect of the lines.Another factor lies in the difference between the rail in the traction network with other conductors: the rail has special ferromagnetic characteristics with irregular cross-sectional shapes,which makes the calculation of the traction network line parameters even more complex.In this paper,the impact method for the testing of soft magnetic material properties was employed to measure the magnetic properties of P60 steel rails.The accurate magnetization data including the basic magnetization curve,hysteresis loop and coercive force of P60 rails were obtained.Then,the electromagnetic finite element simulation software Ansys-Maxwell was applied to calculate the precise impedance and frequency variation parameters of the rail.Based on this method,a parallel multi-conductor transmission line theory was used to design a set of traction network parameters calculation scheme that fully considered the special ferromagnetic characteristics of the rail.Finally,the frequency-dependent impedance parameter matrix and the frequency-dependent admittance parameter matrix of an actual line were calculated using the above scheme.This study provides a line impedance calculation scheme and abundant data for future research on the traveling wave distance measuring of the traction network.