Research On Lightning Protection Of High-speed Railway Catenary Based On Arc Compressed Gas Jet Method

The development of high-speed railway in China is more and more rapid,along with the strategic policy of'belt and road' in China,China's high-speed rail has accelerated its exports in Southeast Asia and Africa,most of which are located in tropical and subtropical regions.Lightning activities are frequent,which puts forward higher requirements for the safe operation of high-speed rail.High-speed rail catenary does not have a backup system.Once lightning strikes lead to insulator damage,line tripping will affect the normal operation of the high-speed rail.This thesis presents a method of arc extinguishing with compressed jet air to solve the problem of high-speed rail catenary lightning protectionIn this thesis,the basic properties of arc and the wall-confined arc model are studied,then the thesis studies the water-cooled-channel arc compression,self-magnetic arc compression and gas longitudinal blow arc compression in the arc extinguishing tube.The results show that the three kinds of arc compression effects promote each other and reduce the arc radius.The magnetic suction and thermal effect of arc make the pressure in the arc extinguishing chamber established,then the longitudinal arc blow finally leads to the extinguishment of the arc.The length of flashover path is calculated to be 3.57m when the arc rate of parallel clearance of 25kV high-speed rail catenary tends to zero.The temperature at arc inflection point of adjacent arc extinguishing chamber is simulated by CFD simulation software Fluent.The result shows that the arc is rapidly cooled by air flow and is broken and extinguished within 2.5ms.The lightning impulse discharge voltage of the device is tested.According to the experimental data,the 50%discharge voltage of the device is calculated to be 303.6 kV,and the volt-second characteristic curve of the device and the insulator is drawn.Continuous power frequency current extinguishing test is carried out on the device.Due to the rapid arc extinguishing effect of the device,the power frequency current can not be detected in the experimentFinally,combined with the structure of the high-speed rail catenary,the tripping probability of the AT power supply line with reinforced line is 15 times higher than that of the positive feeder.Because of the shielding effect of the reinforced line,the tripping events of the T line will not occur.The adjustable metal fittings for T-line wrist-arm insulator,positive feeder suspension insulator and support insulator are designed.Finally,the arc extinguishing and lightning protection devices should be installed on the support insulator under the structure of AT power supply with reinforcement line,and F-line without reinforcement line under the structure of AT power supply mode.