Research on the Protection Principle and Influencing Factors of Zinc Strip on Buried Pipelines around AC Subway

With the rapid development of urban rail transit in my country, the urban subway network is becoming more and more widely distributed, and some urban express lines will adopt the AC power supply system. The subway power supply system produces AC interference to adjacent buried pipelines through electromagnetic coupling of space and resistive coupling of the earth. In engineering, the method of laying zinc strip is often used to suppress the AC interference of pipelines. In this paper, based on CDEGS software, a simulation model of AC subway lines, oil and gas pipelines and zinc strips is built. Starting from the resistive coupling and inductive coupling, the metal induced voltage of the pipeline, the ground potential along the line and coating withstand voltage before and after laying the zinc strips are calculated and discuss the influence of soil resistivity and the spacing between the zinc strip and the pipe on the protective effect of the zinc strip. The study found that the voltage drop of the pipeline coating after laying the zinc strip can reach 95.8%.