Research On Transient Simulation Of Railway Traction Network Struck By Lightning

In recent years,with the rapid development of high-speed railway,the railway network has covered most of China.The structure of railway traction power supply system is complex,so the normal operation of railway traction power supply system will face great challenges in bad weather conditions such as lightning.Lightning is accompanied by high amplitude of lightning magnetic pulse current,although the time is short,but its high amplitude will lead to traction substation tripping or traction network disconnection,traction power supply network cannot supply power to the train normally,seriously affecting the safe operation of the train.Therefore,it is very important to analyze the overvoltage and electromagnetic field changes caused by the lightning magnetic pulse on the traction network,and explore the lightning withstand level and electromagnetic field distribution characteristics of the traction network,so as to reduce the harm of the lightning magnetic pulse on the traction power supply network and ensure the normal operation of the high-speed railway.The main research contents of this paper are divided into two modules,which are: the analysis of lightning induced overvoltage and lightning withstand level of traction network in PSCAD;the analysis of electromagnetic field variation characteristics near the surface of suspension conductor and pillar in CST.Firstly,by referring to the lightning overvoltage analysis method of high-voltage transmission line,the simulation model of lightning traction network is established in PSCAD by modeling the suspension conductor of traction network,traction network pillar,insulator,impulse grounding resistance,arrester and other components.Through the simulation,the different lightning over-voltage situation is analyzed,and the lightning withstand level of traction network is analyzed when different lightning current impacts on different positions of traction network and when the grounding resistance is changed.The simulation results show that the lightning overvoltage caused by the lightning current with longer wave head time is relatively small,and the variation range of lightning point voltage amplitude is smaller when it hits different positions,and the lightning current with shorter wave head is more harmful;reducing the grounding resistance can improve the lightning withstand level of traction network to a certain extent.According to the simulation results,the lightning protection suggestions of adding arrester are put forward,and the protection effect of different types of lightning current after adding arrester is simulated.It is found that the arrester has better protection effect on lightning current impact with longer wave head time.In order to explore the change of electromagnetic field on the surface of lightning traction network,the equivalent model of catenary and lightning magnetic pulse excitation model are built in CST simulation platform.The variation characteristics of magnetic field intensity and electric field intensity at different positions near lightning point are simulated and analyzed in the simulation of the impact traction network.The results show that when lightning strikes the top of the pillar,the positive feeder and the contact line,the top of the train carriage The variation of magnetic field intensity at different horizontal distance and vertical height,as well as the electric field change characteristics near the surface of positive feeder and contact line,provide theoretical guidance for railway electromagnetic protection.