An investigation of earth and sea-return impedances of power electrical cables

This paper investigates the numerical performance of the Wedepohl series and of the Gauss-Kronrod quadrature to calculate ground- and sea-return impedances of power cables. Many computational routines to calculate ground-return impedances of cables used in EMTP-type programs have been proposed without technical justification of their application range. In this paper, we explore the convergence and accuracy of the Wedepohl series based on the number of terms in the series and as a ratio test. As a result, an accurate and stable numerical algorithm to compute ground- and sea-return impedances is proposed. The proposed method is capable of accounting for very low resistivity values and large depths.