Research On The Electric Contact Magnetic Effect Of The High-Speed Railway Pantograph Catenary System And Its Control Methods

A pantograph-catenary system(PCS)consists of a pantograph and a catenary,and it is one of the key equipment of high-speed railways.A good contact between the pantograph and the catenary is an important condition for ensuring the current quality and the safe operation of high-speed train.As the operating speed of trains increases,larger traction current passes through the pantograph-catenary contact pair and produces a stronger magnetic field on the PCS,which cause the magnetic effect on the the electric contact of PCS to become significant.A larger traction current produces a stronger magnetic field on the PCS,which causes the electrodynamic force on the electric contact of the PCS to gradually become non-negligible,aggravate the vibration on the PCS and cause the pantograph to go offline;secondly,when the train speed exceeds 350 km/h,the influence of the velocity skin effect(VSE)gradually becomes not negligible: high-speed sliding causes rapid changes in the magnetic field of the pantograph and the formation of eddy currents,which interferes with the normal flow of the pantograph.At present,the theoretical research on the electric contact magnetic effect in the PCS of HSTs is not deep enough.The lack of systematic solutions for how to solve this problem has become a potential threat to the safe and stable operation of HSTs.Consequently,studying the mechanism of electric contact magnetic effect in the PCS,and designing reasonable optimization schemes based on its characteristics is of great significance.This dissertation attempts to explores the magnetic effect on the dynamical and thermal performance of the PCS.Multi-physics models of the electrodynamic force and VSE have been established alternatively base on the characteristics of the electric contact in the PCS.To mitigate the negative impact caused by the magnetic effect,coping methods have been proposed to optimize the pantograph-catenary matching.The main research work and research results are as follows:(1)The mechanism,characteristics and influence factors of the Pantographcatenary Contact Electrodynamic Force(PCEF)and the Pantograph-catenary Loop Electrodynamic Force(PLEF)have been explored.The mechanism of PCEF and PLEF caused by the electric contact magnetic effect have been analyzed,and corresponding electro-magnetic-force coupling model have been established.The correlation between the electromagnetic field distribution on the contact surface of the pantograph and quantitative distribution of the two electromotive forces has been found.Analysis of the influence of typical factors have been proposed,which shows that the large current caused by instantaneous short circuit raise the electrodynamic force dominantly,resulting in a 17.1% reduction in the contact pressure of the PCS;the contact pressure of the PCS and one-sided current in the pantograph strip also have significant influence on the electrodynamic force of the PCS.(2)Considering the the electric contact magnetic effect cause by high-speed magnetic field,the VSE in the PCS has been noticed.To assess the impact of the VSE on the performance of PCSs,a multi-physics model has been created and is reported in this paper.The model has been validated through experiments and calculation,and the main aspects of its functionality – such as the velocity skin effect,friction and air convection – have been identified and analysed at different speeds.Accordingly,the uneven coefficient of current in the center of the contact surface has been proposed as a quantitative characterization parameter of the VSE,and the temperature rise of the pantograph strip can be reduced by adjusting the VSE.(3)The electric contact magnetic effect of the HSTs has been adjusted,and coping methods to optimize pantograph-catenary matching has been proposed.To reduce the magnetic effect,reducing the uneven coefficient of current and the highest temperature on the pantograph strip have been set as aims.An optimization scheme for adjusting the width and thickness of the pantograph strip is proposed,which can reduce the temperature rise of the pantograph strip by about 11.9%.The influence of the local radius of the contact wire with composite contour on the current distribution and the maximum temperature of the pantograph strip has been studied,and the concept of making the bottom of the contact wire into a composite curve is proposed.The principle and measures for reducing the effect of the magnetic effect of the electric contact of the PCS with an external magnetic field near the trailing edge of the strip has been studied.