Hazard Mechanism And Suppression Strategy Of Stray Current In Metro DC Traction Power Supply System

Metro traction power supply adopts DC power supply mode,and DC power is supplied to metro vehicles through traction substation.Most of the current flows back to the traction substation from the traveling track,but in practice,because the traveling track can not completely insulate the underground metal and the earth,resulting in a small part of the current that can not be completely eliminated leakage from the traveling track,we call this part of the current stray current(also known as stray current).Stray current flow will cause electrochemical corrosion on the running track and nearby metals,which will lead to excessive pressure on the platform rail,thus endangering personal safety.In this paper,the principle and harm of stray current are studied in detail,and a reasonable scheme of stray current suppression is givenFirstly,the mathematical model of stray current in Metro DC traction power supply system is established,the principle of stray current generation is analyzed and calculated,and the corrosion mechanism and harm of stray current to surrounding metals are analyzed and explained.Secondly,according to the mathematical model of stray current in Metro DC traction power supply system,the quantitative analysis and calculation of stray current are carried out,and the traction supply of Metro is obtained.The magnitude of stray current in electric system is related to the parameters of return current such as the positive distribution of corrosion degree,the longitudinal resistance of running track,the resistance of running track to ground and the distance between adjacent traction substations.The relevant calculation formulas are given.Then,the mathematical model of stray current distribution in DC traction power supply system is simulated and analyzed by using MATLAB software,which shows that the above analysis is correct.Finally,according to the above theoretical analysis results,some restraining measures such as adding drainage network,reducing track joints,adding fly ash in concrete,one-point connection of traveling rail drainage network are given.The simulation results verify the correctness of the theoretical analysis,and provide a reference basis for the future actual subway current leakage restraint.At the same time,the paper gives out some restraining measures.The comprehensive control scheme of leakage current from Dalian Metro Line 1 Conference Center to Zhongchang Street is expected to achieve good results.