Research On Offline Electrical Characteristics Of High-speed Rail Pantograph And Catenary Based On FEKO

Nowadays the technology of the high-speed railway is developing rapidly in the world.The increasing speed of trains and the integration of the electronic equipment in trains have led to a more complex electromagnetic environment during operation.Once the offline discharge between the pantograph and catenary occurs,a large number of electromagnetic waves are generated,causing electromagnetic interference(even catastrophic accidents)to communication equipment along the railway line and in the surrounding area.Therefore,the analysis and research of the electromagnetic interference by the offline discharge is an indispensable part of the safe operation of high-speed railways.The main research contents are as follows:(1)The different stages of the offline discharge between the pantograph and catenary have different electrical characteristics.In the physical process of the discharge,the different discharge stages(initiation,ignition,extinguishing)are coupled by the electromagnetic field and circuit.The arc resistance in the lumped parameter circuit of the arc of the offline discharge is replaced by an equivalent resistance,which is realized using the S function in Simulink.Through simulation,the current and voltage between the pantograph and catenary are obtained and analyzed.It is concluded that the overvoltage and harmonic distortion rates are large when the initial phase of the ignition is 90° and 270°,with the phase being the smallest at 0° and 180°.(2)Using FEKO,a three-dimensional mathematical model for the offline electromagnetic interference of the pantograph and catenary is established.And its correctness is verified.According to the different contact wire lengths and frequencies,the variation law of electromagnetic noise directly and laterally above the pantograph is studied.The contact wire lengths from the 10λ to 160λ are mainly studied.Their attenuation characteristics are almost consistent and the attenuation speed gradually slows down as the distance increases;The frequencies of 3MHz,10MHz,20MHz,and 30MHz are selected for research.The electromagnetic radiation intensity in the same area inside and outside the locomotive increases as the frequency of the interference source increases.At different contact line lengths and interference source frequencies,they have attenuated to-25dB to-40dB over the lateral distance of 150m.No serious impact on the communication system along the railway.(3)The electromagnetic noise inside the locomotive is studied by adding the near field of XY,YZ and XZ planes,which are the same length,width and height as the car body.The final result is that the decay of the electric field becomes progressively slower as the frequency increases,provided that the body and window materials remain unchanged.(4)The voltage and current of the offline discharge between the pantograph and contact wire are measured by an advanced experimental device under the typical working conditions of the high-speed railway.The voltage waveform is transformed by FFT.It is found that the harmonic frequency is mainly concentrated in 0.77MHz,1.6MHz,2.6MHz,3.8MHz,5.5MHz,8.8MHz,11MHz,21.8MHz,36MHz and so on.These experimental results provide the basis for the selection of the radiation sources of the off-line discharge between the pantograph and catenary.The research results of this article provide a reference for the electromagnetic protection of the communication and electronic equipment around railway systems.