Research On Characteristics Of Lightning Strokes And Warning Method To High-speed Railway

Due to crossing different regions,the geographical and climatic differences along the high-speed railway are also significant.Overhead railway lines were widely used to support the train run in a high speed,but at the same time,the high catenary increased the probability of lightning strikes,which made the power supply system failure and affect the operation of the railway systems.Lightning energy enters into power supply and traction systems not only through catenary,also causes insulator flashover even communication and signal systems failure by inductive overvoltage and lightning has became an important aspect of affecting the safe operation of the electrified railway,especially the high-speed railway.Therefore,study characteristics of lightning disasters and strokes of railway lines and the lightning disaster mechanism to the comprehensive grounding systems has important significance in theory research and engineering value in lightning protection of high-speed railway.Firstly,the mechanism of spatial electric field distortion induced by lightning to the high-speed railway line in lightning weather and the lightning-stroke characteristics are studied.The research is based on random-leader developing mode and establish the railway catenary spatial electric field physical calculating model,numerical calculation and simulation were used to analyze the connecting process between the downward leaders and the catenary,influence from the catenary to the downward developing direction and placement and the atmospheric electric field was also studied.At the end of the dissertation,the transient characteristics of the lighting currents that enter into the traction power supply system are analyzed.Secondly,the lightning-striking transient responses of the grounding system are studied.According to the damage problems caused by the grounding potential rise of the railway comprehensive grounding system,by observing and analysis of the injected lightning currents to the artificial-triggering lightning,the transient responses and energy distribution of the induced lightning currents and overvoltage of the grounding system are studied.The changes of currents waveform and the hazard-caused mechanism of grounding potential rise of the grounding grids were analyzed.Thirdly,lightning monitoring and early warning methods are studied in this paper.The lightning activities and distribution are analyzied.The observation data from Doppler weather radars and lightning location systems were used to warning the early lightning risks.By analyzing the radar basic scanning data and finishing interpolation and meshing of the spatial data,the study finished layered construction,identifying,tracking and prediction ofthe thunderstorm clouds.so as to realize 0-1 hour early warning for the time and areas of lightning flashes.Finally,the online monitoring technology and method of the grounding parameters are researched in this study and realizing monitoring and warning to the grounding systems operating status.In order to measure the grounding resistance for the comprehensive grounding system of the railway line which crosses regions in long distance,an intelligent monitoring technology and the measuring method were developed based on Internet in this dissertation for the lightning protection grounding system,and the continuous operating data of railway comprehensive grounding system was acquired and collected,then analyzed the influence relationship between meteorological factors and the grounding parameters.The variation rule of ground resistance of vertical grounding electrodes under horizontal soil stratification is studied and analyzed.