Simulation of the operation modes of the catodic protection complex of pipelines in the approach of overhead power lines

Purpose. The purpose of the work is to establish the dependences of the levels of the protective potential of the system of protection of underground steel pipelines when approaching and/or crossing overhead power lines. Methodology. To achieve the goal, the methods of the theory of equivalent electric circuits and the theory of the electromagnetic field, implemented in the packages of applied computer programs Matlab/Simulink and COMSOL Multiphysics, were used. Findings. The spatial distribution in the soil of the induced electric field of the overhead power line in the direct location of the pipeline, which varies with a frequency of 50 Hz, was determined. The distribution of both constant and alternating voltage on the pipeline relative to the soil is given. An analysis of corrosion processes in the pipeline was carried out, on the basis of which the relatively safe flow of corrosion processes in the pipeline under the action of simultaneously occurring alternating current with a frequency of 50 Hz and direct current was investigated. Originality. The scientific novelty of the work consists in determining the regularities of the influence of overhead lines on the nature of the distribution of the protective potential of cathodic protection stations with variable changes in the configuration of pipelines and laying conditions. The existence of significant deviations of the levels of the protective potential in the presence of a variable polyharmonic component of the signal is proven. On the basis of the study, it was established that under the accepted initial conditions, both criteria are unsatisfactory in some sections of the pipeline near the power transmission line. Practical value. The practical significance of the research results is in determining the set of technical characteristics of the electrotechnical complex of protection against electrochemical corrosion, which allows ensuring the necessary levels of protective potential in the presence of a source of stray currents (overhead power lines).