3D electric geometry model on direct lightning and induced lightning trip-out risk of electric railway

Lightning strike directly on traction network can lead to direct lightning overvoltage, while lightning strike on the ground around traction network can lead to induced lightning overvoltage, and these two factors are the main factors leading to lightning fault of electrified railway. This paper built 3D lightning strike electric geometry model which considered sag basing on the actual traction network structure parameters and calculated the 3D lightning strike exposed surface of both feeder wire and messenger wire, figured out lightning finally stroke the feeder wire when leader lied in 3D exposed surface of feeder and likewise stroke the messenger wire when leader lied in 3D exposed surface of messenger, and these two factors can lead to direct lightning overvoltage. If lightning strike outside the 3D exposed surface of feeder and messenger wire, induced lightning overvoltage will be generated. Based on the lightning parameters around high-speed railway, trip-out rate of direct lightning and induced lightning will be calculated, and the model and algorithm is verified by actual lightning data. It turned out that the results calculated by theoretical arithmetic and actual lightning protection operation experiences have a relative error of only 6.9%, which improve the accuracy of lightning protection calculation, and provide scientific evidences to finding electrified railway´s high risk of lightning strike area.