Research On New Urban Rail Transit Stray Current Monitoring And Protection System

In recent years,with the continuous development of social economy,China’s urban rail transit has entered a stage of rapid development.Dc traction power supply system is mostly adopted in urban rail transit,and the backflow current is guided to the negative pole of traction substation by moving rail.Since the rail cannot be completely insulated from the ground,part of the backflow current will enter the ground to form stray current.Stray current causes a series of hidden safety hazards,such as electrochemical corrosion of buried pipelines along the urban rail transit and affecting the normal operation of surrounding power equipment.Therefore,it is of great significance to effectively monitor the stray current of urban rail transit and to predict and protect its potential hazards.This paper introduces the structure of urban rail transit power supply system,analyzes the formation mechanism of stray current in the operation process of urban rail transit system,discusses the hazard of stray current and the corrosion mechanism of buried metal structure.Combined with the power supply mode of urban rail transit,the interval resistance distribution model of single-bilateral power supply mode is established,and the analytical expressions of rail potential and stray current distribution are derived on this basis.The influence of various factors on stray current is analyzed through MATLAB simulation,which lays a theoretical foundation for the research on stray current monitoring and protection system of urban rail transit.In order to monitor and protect the stray current corrosion state of urban rail transit,the measurement methods of the required monitoring parameters are studied,the shortcomings of the traditional measurement methods of rail longitudinal resistance and rail ground transition resistance are discussed,and an online measurement method is proposed.In this paper,the measures for stray current protection are expounded.based on the analysis of the deficiency of the discharge method in stray current protection,a discharge flow setting model based on BP neural network is proposed.the data show that the model can effectively calculate the discharge flow.On the basis of the above research,a new urban rail transit stray current monitoring and protection system based on the mixed architecture of Client/Server and Brower/Server mode is proposed.System will return tank,feeder,rail potential limiting device such as device parameters into the scope of monitoring,the system of the main equipment involved in,such as smart sensors and intelligent monitoring device for the design of the hardware and software aspects,and write the monitoring software of microcomputer management system,can realize monitoring protection information display and query.Finally,the test system platform was built in the laboratory to verify the reliability and stability of the monitoring function of the system.The TCP and UDP communication test between the intelligent monitoring device and the microcomputer management system was conducted to realize the remote setting of the IP address of the intelligent monitoring device by the microcomputer management system to meet the actual needs.