Experiment And Simulation Of Factors Affecting Pantograph-catenary Offline Electromagnetic Disturbance Characteristics

Researching the electromagnetic interference characteristics of the off-line pantograph has significant implications for promoting high-speed rail safety,ensuring normal train operation,and improving the safety of train control systems.Currently,scholars at home and abroad have conducted extensive research on the arc discharge between pantographs during off-line processes.However,the impact and mechanism of the influencing factors such as the progressive speed,phase,and zero interval on the electromagnetic interference characteristics of off-line pantographs have received less attention.To address these issues,this thesis proposes the following research content and innovative points:(1)To address the issue of the influence of asymptotic speed on offline arc discharge in catenary systems,this thesis proposes an experimental method using the "potential energy-kinetic energy" and "relationship between angular velocity and linear velocity" to simulate offline arc discharge in catenary systems.A pendulumtype moving electrode discharge simulation device was designed and constructed to avoid the influence of AC voltage changes.A high-voltage DC source was used for power supply,and high-voltage DC tests were conducted to investigate the effect of relative motion between the pantograph and overhead contact wire on the transient discharge current and the time-domain and frequency-domain characteristics of the electromagnetic field Experimental results indicate that faster longitudinal converging motion between the pantograph and the overhead contact line generates higher peak pulse current,steeper rise front,and increased electromagnetic radiation intensity.(2)This thesis addresses the technical challenge of determining the impact of power phase on offline electromagnetic interference characteristics in bow nets,which is difficult to ascertain through experimental means.To overcome this challenge,a high-voltage AC experimental apparatus was designed and constructed.For the first time,an experimental method was proposed to investigate the relationship between different discharge distances and breakdown voltages under identical conditions,as well as the corresponding effects of different breakdown voltages on the power phase.Additionally,measurements of discharge current and radiation field were conducted.The experimental results demonstrated that the influence of power phase on bow net discharge characteristics exhibited a positive correlation with the rate of voltage variation.By differentiating the voltage curve once and twice,it was found that the maximum rate of voltage variation occurred in the range of 0 to 90 degrees,particularly near the zero-crossing point.This corresponded to the highest pulse current and strongest radiation field.As the phase increased,the rate of voltage variation decreased,resulting in a reduction in the pulse current and radiation field amplitude.The impact of phase was found to be highly significant,and special attention should be given to the vicinity of the zero-crossing point.(3)In order to address the impact of zero crossings on the electromagnetic interference characteristics of offline arc discharge in the overhead contact system,especially during the process of offline arc discharge in the overhead contact system,a test device for high-voltage discharge electromagnetic interference in the overhead contact system and a half-wave zero crossing test device were designed and built.Comparative experimental results showed that the zero crossings of high-voltage AC50Hz had a significant impact on the characteristics of the arc and discharge pulse current in the overhead contact system,and this phenomenon became more pronounced with longer zero crossing times.(4)Through the simulation method of arc shielding experiments,it is demonstrated for the first time that the offline circuit structure of a pantograph(including the arc)is the excitation source of offline electromagnetic interference.In other words,the rate of change of current with respect to time(d I/dt)in the offline circuit of the pantograph is the true excitation source,and the arc is only a part of that excitation source.Apart from the radiation emitted by the arc itself,the circuit structure also generates strong electromagnetic radiation externally.Additionally,as the circuit acts as an equivalent antenna,the variation of the arc causes significant electromagnetic radiation due to the change in circuit current(d I/dt).Furthermore,the impact of phase on the offline discharge characteristics of the pantograph is verified,and an analysis of the electromagnetic field distribution inside and outside the carriage under offline discharge conditions is conducted.