Study On The Interference Law Of AC Transmission Lines On The Cathodic Protection Potential Of Long-distance Transmission Pipelines

In the transportation process of oil and natural gas,long-distance pipeline is the most important transportation method.With the rapid development of modern industry,the length of the pipeline is increasing,but because the transmission line erection path and long-distance pipeline buried route selection principle is basically the same,the phenomenon of parallel and cross between the pipeline and transmission line is difficult to avoid.At this time,transmission lines can be inductively coupled,resistive coupling and capacitive coupling and other ways to form induction voltage and stray current interference in the pipeline.Interference will even affect the effect of cathodic protection of the pipeline when it is serious,and will accelerate the corrosion of the pipeline.Therefore,it is important to study the influence law of AC transmission lines on the cathodic protection potential of long-distance transmission pipelines.In this paper,in order to study the influence of AC transmission line on the cathodic protection potential of long-distance transmission pipeline through inductive coupling,the simulation model containing long-distance transmission pipeline,transmission line,auxiliary anode,air domain,soil domain,etc.is established based on COMSOL Multiphysics finite element simulation software using transmission line conductor type,steady-state operating current and other transmission line related parameters and pipeline related parameters,and the The cathodic protection potential distribution of the long-distance transmission pipeline using the external current method is simulated in the frequency domain at different voltage levels,parallel spacing,conductor-to-ground height,conductor arrangement,pipeline burial depth and soil resistivity,and the cathodic protection potential distribution of the pipeline under different conditions after electromagnetic interference is obtained and compared.The results show that when the pipeline is subjected to electromagnetic interference,the peak cathodic protection potential appears at both ends of the pipeline,and the induced voltage increases from near the center of the pipeline to both ends of the pipeline.Voltage level and wire arrangement should be considered as the key electromagnetic interference factors when planning pipeline burial routes or transmission conductor erection lines.Based on the established model,we use the App developer in COMSOL to develop a simulation platform for the effect of AC transmission lines on the cathodic protection potential of pipelines.The simulation App is packaged using COMSOL Compiler,and the simulation App can be used for independent simulation applications in a non-COMSOL Multiphysics environment.The parameters can be changed according to the engineering field data to analyze the geometric style of the model,the mesh division and the cathodic protection potential distribution of the pipeline in different cases,which can be used as a reference for the design of buried lines and cathodic protection schemes for long-distance transmission pipelines.