Research On Stray Current Corrosion Prediction Technology For Urban Rail Transit

DC traction power supply system is widely used in urban rail transit. China is inpeak period of developing urban rail transit,but the safety and reliability of DCtraction system is the basic requirement for urban rail transit. In DC traction system,we regard the line tracks as reflux pathway, but it can’t completely be insulated overthe ground, thus some current blab from orbit to the track or the surrounding soil,called the stray current.The stray current could corrode the ballast,buried metalpipeline,buried steel structure and metal equipment of the rail transit, resulting in thedecreasing of the strength of the metal,the service life of equipment isreduced,threatening the safe operation of the subway,probably causing seriouseconomic losses and casualties.So it is necessary for us to monitor accurately the straycurrent,and forecast the stray current corrosion situation,so as to ensure the safeoperation of urban rail transit.The pape will start from the following several aspects:Firstly,It’s difficult to establish precise flow system analysis model,based on theactual working condition which is simplified and qualified,and combined with thecharacteristics of the metro dc traction return system,I establish the reflux systemanalysis model of the structure of the orbit-earth.In two ways of unilateral andbilateral power supply system,the subway stray current distribution mathematicalmodel is derived,and the simulation is verified,according to the results ofsimulation,the paper analyzes the metro stray current distribution law and thevarious factors affecting the distribution,it is of great significance to monitor andprotect the degree of stray current corrosion.Secondly, this paper introduces the basic definition of metal corrosion, and theconcept of metal alvanic corrosion;Subway stray current corrosion mechanism isanalyzed, and the risk index and judgment of the metro stray current corrosionare dentified.Combined with the experience and the operation situation of today’sdomestic subway,the stray current will bring a series of new problems and harm, suchas the damage of buried steel structure and metal pipelines, endangering the safety ofpersonnel and so on.Thirdly,Paper introduces the basic concept of artificial neural network. In viewof the structure and algorithm of BP neural network,this paper carries on the detailedanalysis and introducing,and designs the stray current corrosion prediction modelbased on BP neural network.Through the establishment of the BP neural network model,this paper predicts reference electrode offset value and buried reinforced straycurrent density.By matlab simulation result,the precision of the pre diction methodbased on BP neural network model is high,reliability is as well, which has the veryhigh application promotion value.Finally,this Paper introduces the basic concept of expert system and Web servicetechnology,analyzes the characteristics of the expert system for subway straycurrent.The architecture of expert system is given,and the monitoring content andmethod of this expert system is given.It establishes the stray current corrosion expertsystem based on Web. According to the application to practical engineering,it showsthat the expert system can not only implement the accurate monitoring of metro straycurrent, can also analyze according to the collected data,and decide whether to call thepolice,and to forecast the future of stray current corrosion,which can provide thesafeguard for the safety of subway operation.