Research On Lightning Protection Of Electrified Railway Traction Network In Arid Region

With the vigorous development of the transportation in western region, the mileage of electrified railway under construction and planning is also increased. However, due to the specialty of harsh environment, complex terrain and weakness of power supply in western areas, the lightning protection level of railways in such areas is relatively lower. Therefore, it is very significant to research the lightning protection of the electrified railway traction network in arid desert.By analyzing the traction power supply mode and spatial structure, the traction network electric geometry model(EGM) is established. According to the analysis of pillar, striking distance and exposed arc. The results can be drawn as follows: AF line is the most vulnerable part of traction network to lightning, next in turn is the pillar and carrier cable. Because the protection lines are protected by other suspension wires, they are not affected by lightning hazards.When offering electric energy to the trains, the traction network's insulation system is always suffering the power frequency voltage. In order to calculate the lightning withstand level more accurately, the formula under the situation of lightning striking pillar and striking suspension wires with considering the power frequency voltage is derived in the thesis. The results show that power frequency voltage has a great effect on the lightning withstand level of traction network. Thus, it can not be ignored in the lightning protection calculation in traction network.In order to analyze the relationships between environmental factors and the lightning withstand level, lightning traction network model is established based on the electro-magnetic transients program(EMTP). The results show that with the increase of air temperature and soil moisture content, the lightning resisting level of traction network increases. Furthermore, lightning resisting level of traction network is higher in gravel soil while lower in loess. Finally, under the same environmental factors, lightning resisting level of AF line insulator is always the lowest no matter it is caused by the counterattack of lightning striking on the pillar or on the suspension wires.In order to enhance the lightning resisting level of traction network in arid desert areas, the measures of replacement method, deep buried grounding method and laying drag reduction agent method is analyzed in the thesis to optimize grounding system and reduce grounding resistance. In addition, the protective effects of traction network insulator in AF line is simulated and analyzed when installing the arresters with intervals of 1, 2, 3 pillars. The results show that due to the arresters' protection distance and lightning points' randomness, lines can be protected only when lightning point installed lightning arrester. Thus, in order to ensure full protection, arresters in the whole line need to be installed. But considering the capital investment and maintenance workload, it is more reasonable to install the arresters on every other pillars in arid desert areas.