Low-frequency Electromagnetic Coupling Between a Traction Line and an Underground Pipeline in a Multilayered Soil

This paper presents a low-frequency electromagnetic interference study between a single-phase overhead traction line and a nearby underground pipeline, with emphasis on how the soil structure affects induced voltages. Soil parameters are determined from real field measurements, which results in a soil model composed of six layers. Mutual impedances are computed using the finite element method (FEM) and compared with a modified version of the original Carson equation, in which the term describing the soil conductivity is replaced by a uniform equivalent of the multilayered structure. Results show an excellent agreement between the proposed approach and the reference values, along with a considerable performance gain, compared to the FEM formulation of the multilayer soil structure. In addition, simulations highlight the errors in which one occurs when the soil structure is not properly accounted, especially when the apparent resistivity is used instead of the stratified parameters.