Research On The Dynamic Distribution And Leakage Monitoring Of Stray Current In Urban Rail Transit

At present,China is the fastest country in development of urban rail transit aroud the world,whose urban rail transit construction projects are growing at an annual rate of double.Stable and reliable DC traction reflux system is the basic guarantee for the safe and stable operation of urban rail transit system.What has very important significance for the urban rail transit system is that building the model of reflux system with more perfect parameters and structure,analyzing the dynamic distribution of stray current and rail potential,and studying the calculation method of stray current leakage which in a wide range of reflux system.This paper focuses on the related problems caused by the stray current of urban rail transit,elaborating the composition structure and feeding arrangement of DC traction power supply system and its reflux system,analyzing the cause of stray current in reflux system and the corrosion mechanism of stray current to buried metal structure.The model of locomotive traction running is established according to the idea of three classic traction strategies.The static distribution model of stray current was based on the equivalent model of n-layer reflux system.By combining the model of locomotive traction running and calculation of traction power supply,the paper builds the dynamic distribution model of stray current in reflux system under different traction strategies.The conclusion of distribution of the reflux system stray current and rail potential in different traction strategies is summarized according to simulation analysis of stray current dynamic distribution model.According to the distribution,the means of reducing the risk of stray current corrosion in reflux system are emphasized respectively from two angles of reflux system stray current control and locomotive traction running.The expression of the relationship between stray current and rail potential is deduced according to stray current static model of n-layer reflux system,this expression is suitable for different layers of reflux system.On this basis,a calculation method of stray current leakage in wide range reflux system is proposed,its calculation range is expanded from the traditional local area to the locomotive running range.With the help of locomotive traction running model based on three kinds of classical traction strategies,the effectiveness of the stray current leakage as the basis for evaluating the risk of stray current corrosion in the reflux system is verified according to the simulation and analysis of stray current leakage in different traction strategies.Through the field test,it is proved that the proposed stray current calculation method is reasonable and effective.Based on the calculating method of stray current leakage,the existing technical conditions and equipment configuration level of urban rail transit system,the test method of static parameter and the access to dynamic parameters are given and the system scheme which monitors stray current leakage of urban rail transit is constructed.