Transient electromagnetic interference on buried pipelines caused by double circuit overhead power lines

Analysis of the electromagnetic interference (EMI) between overhead lines (OHL) and nearby buried pipelines requires the accurate calculation of the self and mutual electrical parameters of all conductors in the arrangement. This becomes more important when investigating high-frequency (HF) EMI. Common approaches presume that the impact of the mutual capacitive coupling as well as the frequency-dependent soil characteristics can be disregarded. However, such approximations may result into estimates that overlook critical interactions. In this article, a recent formulation for calculating both the mutual impedance and admittance between overhead and underground conductors is adopted to investigate HF EMI on a pipeline caused by lightning strikes in a double-circuit OHL. Wave propagation characteristics and transient responses are computed using both frequency-dependent and constant properties soil models to evaluate the importance of the proposed approach on EMI studies; significant differences are observed. Comparisons are also carried out with approximate earth formulations, where the influence of the displacement current is disregarded. In addition, the impact of the pipeline burial depth is examined.