The Research On Pantograph-Catenary Arc Characteristics And Control Method Under Low Air Pressure And Strong Airflow

High-speed sliding electrical contact systems are widely used in rail transit,electromagnetic ejection,aerospace,grounding carbon brushes,and other fields.The pantograph-catenary electrical contact system is the core element of the energy supply of high-speed trains,and the fault caused by the arc of the pantograph-catenary is the primary factor that threatens the stable transmission of energy in high-speed railways.However,with the development of modern rail transit,high-speed trains are faced with the challenge of operating in a more complex environment.With the implementation of the strategy of the Sichuan-Tibet Railway,high-speed trains will operate in low air pressure and strong airflow environment for a long time.Under low air pressure,the arc sustaining ability is stronger,the arc longitudinal drift is more serious,and it will float to the rigid busbar for development,which will cause the performance of the rigid busbar to decline,and even lead to the flashover of the support insulator.Once the train breaks down in a high-altitude and low air pressure environment,it is extremely cold and oxygen-deficient,and rescue is extremely difficult,and the harm and loss will be more serious than that under normal pressure.Therefore,it is of great significance for the safe energy supply of high-speed trains in low-pressure and strong airflow environments to explore the difference between the pantograph-catenary arc characteristics in the low-pressure environment(0.6 atm-1 atm)and the normal pressure and to find out how the arc vertical develops under the low pressure and strong airflow,why it develops,and to find out how to control it.Based on this,this paper studies the characteristics and control methods of pantograph-catenary arc in low air pressure and strong airflow environment.The main work carried out is as follows:First,the low air pressure and strong airflow arc test and diagnosis platform were established,the arcing process under different air pressures and airflow speeds was photographed,the arc root motion characteristics and arc voltage and current waveforms were analyzed,and the physical process of the arc re-ignition and the arc root jump in a low-pressure environment was explored.The magnetohydrodynamics(MHD)model of pantograph-catenary arc in low pressure and strong airflow environment was built to explore the distribution characteristics of arc temperature field under different air pressure and airflow velocity.The reason for the more frequent arc root jumping and arc re-ignition under low pressure is theoretically explained.Secondly,the development process and longitudinal drift characteristics of pantograph-catenary arc under different air pressures and airflow velocities were experimentally studied,and the arc column transverse stretching-time characteristic curves and arc column longitudinal drift height-time characteristic curves under different air pressure and airflow velocity were established.The characteristics and influencing factors of arc drifting under different air pressure and airflow speed were explored.The physical process of the arc column drift to the rigid busbar and the arc root jumping mechanism on the busbar are summarized and analyzed.In order to clarify the mechanism of the above phenomenon,a numerical calculation model of the multi-field coupled stress of the pantograph-catenary arc was established,and the variation law of the multi-stress of the arc under different air pressures and airflows was analyzed.The force at different stages and the mechanism of action on arc drifting motion at different development stages.Theoretically revealed the force of pantograph-catenary arc in different development stages in low pressure and strong airflow environment,and revealed the mechanism of arc multi-field coupling stress on arc drift motion in different development stages.Finally,a new control method based on a transverse magnetic field to suppress arc drift is proposed.The method utilizes an external transverse magnetic field to suppress the arc’s longitudinal drift and transverse stretching so that the arc is constrained to develop in a local range near the arc starting position,thereby realizing the regulation of the arc’s motion behavior.The optimal model of magnetic field regulation under different airflow velocities,air pressure,and current conditions is theoretically deduced:B=(?),and the optimal external magnetic field fitting formula under different airflow velocities and air pressure levels is fitted based on experiments.This method provides a theoretical basis for suppressing arc drift under low air pressure.