Resarch On Lighting Leader Fractal Model And The Attracted Lightning Performance Of High-Speed Railway Catenary With Viaduct Bridge

With the rapid development of economy, people’s living standard has been continually improving, the imbalance between supply and demand of the Chinese transportation is becoming more and more serious, and the high speed railway is developing very fast rely on its advantages, such as quick speed, large quantity of transportation and punctuality. The high-speed railway mileage is long in China, it pass though complex terrain and landform. A large number of Viaduct Bridges had been adopted in the process of high-speed railway construction. With the increase of ground clearance of high-speed railway power supply system, the lightning drawing range is magnified and the possible of subway attracted by lightning is increased. Therefore it is necessary to research on the attracted lightning performance of high-speed railway with Viaduct Bridge and recommends the improving lightning protection scheme. This paper mainly researches on the attracted lightning performance and influence factors of high speed railway with Viaduct Bridge.In this paper, considering the practical construction of high-speed railway with Viaduct Bridge, using MATLAB establishes the lightning leader fractal propagation model of high-speed railway with Viaduct Bridge based on lightning fractal theory, the lightning strike characteristics of high speed railway with Viaduct Bridge is analyzed, and then the lightning fractal development path and were space electric-field distribution are got. Research results show that lightning fractal development path reflects that lightning has the certainty of developing towards the direction of maximum space electric field intensity and the randomness of fractal development. Lightning leader strikes the ground targets after lots of fractal development. And with the height of lightning leader final breakdown is in the range of 80-120m.Secondly, considering the feature of power supply system of high-speed railway in China, researches on the influence of working voltage on catenary and feeders, height of viaduct bridge and lightning current amplitude on the space electric-field distribution. Research results show that when considering the working voltage of catenary and feeders, the value of space electric field intensity near catenary and feeders is slightly larger than not considering working voltage. The height of Viaduct Bridge on high-speed railway plays a bigger influence on the space electric-field distribution near the viaduct bridge. And with the lightning current amplitude play a greater role in the space electric-field distribution and lightning fractal development path.Finally, the influence rule of lightning current amplitude, lightning leader initial side distance, height of lightning leader initial fractal and height of viaduct bridge on the lightning drawing range of viaduct bridge is studied. Research results show that with the increase of lightning current amplitude, the lightning drawing range of Viaduct Bridge increased. With the lightning leader initial side distance increasing, the probability of feeders stricken by lightning decreased and the probability of ground and bridge stricken by lightning increased. With the increase of height of lightning leader initial fractal, the probability of feeders stricken by lightning decreased. With the height of Viaduct Bridge increasing, the probability of feeders stricken by lightning increased. The lightning drawing range of Om Viaduct Bridge is 80m, the lightning drawing range of 30m Viaduct Bridge is 145m. With the increase of height of Viaduct Bridge, the lightning drawing range of increased and the lightning problems of Viaduct Bridge become more serious.