Research On Electromagnetic Disturbance Characteristics Of Pantograph-catenary Offline And Pantograph Lifting

The pantograph-catenary off-line operation and pantograph lifting operation in EMU operation will interrupt the current collection of EMU,generate pantograph-catenary arc and further cause transient response of on-board circuit.This transient effect will not only produce surge overvoltage on the on-board circuit and car body,cause on-board electronic equipment fault or even insulation breakdown,but also produce conduction and radiation interference to the trackside electrical and wireless communication system,which will seriously endanger the train operation safety.At present,the research on Pantograph-catenary arc discharge focuses on the electrical characteristics of stable arc combustion state,and the research on Pantograph-catenary discharge radiation focuses on the radiation pattern and propagation path attenuation at the core frequency point.However,in practice,the whole process of arc discharge includes not only the stable arc stage,but also the arc extinction and reburning process.Compared with the stable combustion state,the peak value of transient overvoltage produced by the arc extinction and reburning process is usually higher.Therefore,it is necessary to study the complete dynamic process of pantograph-catenary discharge,so as to study the transient overvoltage characteristics caused by pantograph-catenary discharge more deeply and prevent the harm caused by pantograph-catenary discharge.In addition,the energy radiated by the pantograph-catenary discharge is not concentrated in a single frequency point,but distributed in a wide frequency band.It is necessary to expand the research of the pantograph-catenary radiation disturbance from the core frequency point to the main frequency band,so as to better study the pantograph-catenary discharge radiation characteristics.This thesis first analyzes the impedance and electrical characteristics of pantograph-catenary arc under stable combustion state,and then further explores the critical conditions of pantograph-catenary arc combustion.For the first time,a full dynamic pantograph-catenary arc modeling method is proposed to realize state switching by determining the critical length.Taking a certain type of short intercity EMU as reference,the pantograph-catenary electromagnetic transient overvoltage simulation model is established.Based on the model,the transient overvoltage characteristics of the primary side of the voltage transformer and the bottom axle end of the vehicle during pantograph lifting and lowering are simulated and analyzed under three typical conditions of stable arc combustion,arc extinction and arc reburning.Under the condition of static pantograph lifting,the surge overvoltage at the bottom axle end and voltage transformer position of a certain type of short braided intercity EMU is tested and studied.The rationality of the modeling and the accuracy of the simulation results are verified through data post-processing and analysis.This study further reveals the transient overvoltage characteristics of pantograph-catenary discharge,and provides a reference for the study of pantograph-catenary discharge overvoltage.Taking a short-length intercity EMU as reference,a model of pantograph-catenary discharge radiation disturbance is established based on electromagnetic simulation software.The transient overvoltage time-domain waveform of pantograph-catenary discharge is extracted as the excitation source injection model.The time domain and frequency domain characteristics of the space electric field of the pantograph-catenary radiated disturbance in the frequency range of 20-100 MHz are simulated.The static pantograph lifting operation is carried out under the operation environment of a short braided intercity EMU,and the space radiated electric field of pantograph-catenary discharge is tested.The test results show that the time domain waveform of space radiated electric field obtained by simulation has the same waveform characteristics as the test results,and the simulation spectrum is close to the test results,and the amplitude shows a trend of decreasing with the increase of frequency.This study is helpful to further analyze the harm of pantograph-catenary discharge radiation disturbance to sensitive equipment..