Research On Key Technologies Of Insulation Damage Location Of Metro Rail Based On Fiber Bragg Grating

In recent years,with the rapid development of social economy and the acceleration of urbanization,urban traffic congestion is becoming more and more serious.The existing transportation system can no longer meet people’s daily needs.Rail transit is characterized by its large volume,fast speed,safety and reliability.With technological advantages,it has become a means of transportation in major cities in my country.As of December 31,2020,a total of 44 cities in my country have opened and operated 233 urban rail transit lines,with an operating mileage of 7545.5 kilometers,of which subway occupies 79% of the standard structure of rail transit operating lines.However,as the operating time of the subway increases,the insulation fasteners between the rails and the ground are affected by the environment,stress damage and other factors.Local insulation damage occurs,which causes the leakage of stray current to increase.Corrosion occurs in the metal pipelines such as communication cables,water pipes,gas pipelines,and structural steel bars in interval tunnels,which damages the strength of the metal pipelines and reduces their service life.Therefore,insulation damage monitoring is of positive significance to ensure the safe and reliable operation of the subway.Aiming at the problem of the weak location technology of subway insulation damage,this paper comprehensively uses finite element simulation,laboratory testing,simulation experiment and other methods to carry out research work on the method and key technology of subway insulation damage detection based on fiber grating,and realizes the insulation of subway running rails.The accurate location of the damaged point ensures the safe operation of my country’s urban rail transit.The main research work is as follows:(1)The composition of the subway traction power supply return system and the insulation fastener system are introduced.The resistance model of the insulation fastener is established based on COMSOL.The influence of the surface resistance of the insulation fastener on the insulation performance is analyzed,and the cause of the insulation damage is revealed.(2)According to the structure of the subway traction power supply recirculation system,the recirculation system model was established based on CDEGs,and the electric potential distribution of the insulation fasteners under the condition of no damage,damage points,damage resistance,extreme damage and considering the opening and closing of OVPD was studied,and experimental verification was carried out.A solution for locating insulation damage based on voltage drop detection of insulation fasteners is proposed.(3)A fiber grating-based voltage measurement method for insulation fasteners is proposed,a fiber grating voltage measurement system is constructed,the measurement principle is analyzed,and the measurement system output model is established.Based on COMSOL,a fiber grating voltage sensor cement layer strain transfer model is established,and the bonding is studied.The influence of layer length,thickness and width on the strain transfer coefficient of cemented layer.A method for improving the sensitivity of the fiber grating voltage measurement system was proposed,and the performance test of the measurement system was carried out.(4)Based on the insulation fastener voltage measurement method,the subway insulation damage location plan is proposed,the insulation damage location system experimental platform is built,and the host computer software for data acquisition,storage and insulation damage point location analysis is designed to realize the positioning of the insulation fastener damage point.There are 64 figures,23 tables,and 94 references in this thesis.