Research On Electromagnetic Field Distribution Of Catenary And Its Influences On Lines And Cables Along The Railway

Electrified railway traction power supply system is a typical asymmetrical circuit with unbalanced electromagnetic field.With the development of high speed and heavy haul railway,higher quality electronic components and telecommunications equipments are used in electrified railway,and electromagnetic influences are getting worse.It became an important task and topic to solve electromagnetic compatibility between electrified railway and electronic equipments.Interference sources and objects are analyzed in this paper.This paper focused on the characteristic of power frequency electromagnetic field distribution of DR-NF and AT power supply mode,additional wires affected on electromagnetic field,hazard and interferences influences with some measures of overhead telecommunication lines and railway signal cables along the railway.The analysis of power frequency electric field of catenary was used precise adaptive mesh refinement of finite element method(FEM)and two-dimensional(2D)finite element model of double track railway on DR-NF and AT power supply mode based on Ansoft Maxwell.The results were approximated to the past measured ones,and showed the trendence of electric field intensity out of rail similar to line and the characteristic of maxima of intensity near the rail.It also showed the electric field distribution of AT positive feeder(AF)and found that AF dividing two conductors could weaken electric field intensity in the 5m range of railway center line under the contact wire.Based on the 2D finite element model,the analysis of power frequency magnetic field of catenary was built multi-conductor transmission line model of traction network based on Simulink.Power frequency magnetic field distribution was calculated by the current of traction network.The results showed the trendence of power frequency magnetic field by load current and steady state short circuit current of railway subgrade interval,the characteristic of the maxima and the fast reduction under catenary near the rail.This study also compared with magnetic field distribution of three kinds of short circuit faults of AT mode,and showed the distribution of negative feeder(NF)and AF.It proposed on plans for NF and AF to weaken magnetic field of 6-10 m range of railway center line under contact wire.Then paper focused on the electrical parameters of overhead telecommunication lines and rail signal cables along the railway on the conditions of load and short circuit current.The results got electrostatic induction voltage,mutual inductance coefficient,induced magnetic induction voltage,comprehensive shielding coefficient and noise induction voltage,and checked limit values of hazard and interferences influences.According to the problem of AT model viaduct interval runthrough earth cable and signal cables together in cable trough,it analyzed the influences of signal cable which single ended ground in the condition of load current,T-R short circuit and lightning circuit of protection wire(PW).Finally,it proposed on some plans for additional wire and runthrough earth cable to reduce electromagnetic influences,some measures to reduce influences on telecommunication lines and rail signal cables.