| China’s oil and gas resources are mainly transported by long-distance pipelines.Long-distance pipelines are mostly buried,and cathodic protection is used to protect the pipeline electrochemically.Due to the limitation of geographical conditions,in practical engineering,the light rail track will inevitably be laid in parallel,orthogonal or cross with the long-distance pipeline,and the stray current generated during the light rail operation will interfere with the cathodic protection potential of the pipeline.Therefore,it is necessary to study and optimize the variation law of cathodic protection potential of pipeline under different conditions of track and pipeline.In this paper,the mechanism of light rail stray current and cathodic protection is studied,and the structure model of light rail stray current field is established.The structural model is simulated,and the distribution curves of rail voltage,current and stray current and the compilation file of distribution change function are obtained.The compilation file is called in COMSOL Multiphysics,and the distribution model of the earth and pipe ground potential is established,and the distribution law of the earth electric field and pipe ground potential under the interference of stray current of light rail is analyzed.By adding auxiliary anode to the distribution model of pipeline and ground,the model of pipeline cathodic protection system under different distribution characteristics of pipeline and rail is established,and the influence of stray current generated during light rail operation on pipeline cathodic protection potential under different distribution characteristics is analyzed.Based on the established model of cathodic protection system under different distribution characteristics of pipeline and rail,the software package of cathodic protection potential optimization for pipeline under corresponding distribution characteristics is developed by using APP developer of COMSOL.The pipeline with different distribution characteristics from the track in practical engineering is selected as the optimization object,and the external condition parameters measured in the field are substituted into the software package to solve the protection potential,and the protection potential data measured in the field are compared and verified.The results show that the relative error between the solution value of the software package and the field measured protection potential value is less than 5 percent,which can provide reference for the design of cathodic protection scheme for long-distance pipelines. |
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