Research On Metro Stray Current Protection Measures Based On Mandatory Absorption Current Of Inductor

At present,the DC traction power supply mode is adopted in the subway system.Electric locomotives get electric energy through sliding contact between pantograph and overhead contact line,and the rails are laid as reflux devices.According to the actual situation,the rail can not be completely insulated to the earth,a part of the reflux current will leak to the earth in some poor insulation and form the stray current of the subway.Stray current will corrode buried metal pipelines and equipment,which will seriously affect their service life and working condition.Therefore,the corrosion mechanism,the damage,the protection measures,the distribution law and the influencing factors of the stray current are studied in this paper.On this basis,the protection method based on the mandatory absorption current of inductor is studied.This paper introduces the corrosion mechanism and the harm of the stray current,and briefly analyzes the corrosion protection measures of the stray current,and divides the protection methods into two types: source control method and drainage method.The source control method can reduce the leakage of stray current from the root,and the drainage method is to recover the stray current which has been leaked out.Through the analysis of the two methods,the source control method is the most effective way to reduce the leakage of stray current can be known.The stray current distribution model of "Rail-buried metal-earth" and "Rail-drain net-buried metal-earth" was built under the two modes of single and bilateral power supply,and the simulation was carried out by MATLAB software.The key factors influencing the distribution of stray current were obtained by reasonably adjusting the model parameters.It is known from the simulation results that the selection of power supply mode,the current value of the locomotive from the traction network,the distance of the power supply,the value of the longitudinal resistance of the rail and the transition resistance between the rail and the earth will all have a certain influence on the distribution of the stray current.On the basis of the above analysis,the stray current protection method using the mandatory absorption current of inductor is studied.By setting a special reflux line and using the device of mandatory absorption current of inductor,the traction current will flow back to the traction substation through the special reflux line as much as possible to reduce the current flowing through the rail and reduce the leakage of the stray current.The model is built and the simulation analysis is carried out with the help of MATLAB.Finally,a small power mandatory absorption current of inductor test platform is built,and the feasibility and effectiveness of the method are verified by the experiment.