Effect of conductor angle between transmission lines and neighboring utilities on the accuracy of inductive interference computations

Conventional methods used to analyze inductive interference between electric power lines and neighboring utilities, such as pipelines, railway, and communication lines, are usually based on a circuit model approach. This approach requires that the line parameters of the entire network be computed first, based on an algorithm in which all conductors are assumed to be parallel. When they are not parallel, a piece-wise parallelism approximation is employed. The objective of this paper is to evaluate the accuracy of this approximation, by comparing its predictions with those of a considerably more accurate electromagnetic field theory approach. Various angles are examined, for both load and fault conditions. The accuracy of the circuit approach appears to be good during load conditions, while it increases considerably for a fault occurring at a power line/pipeline crossing, in which case the interference computed with the circuit approach is higher than that computed using the field approach. This paper documents the accuracy of the piece-wise parallel approximation made in the circuit model approach, for representative system conditions and geometries.