Impedances and Admittances of Underground Cables for the Homogeneous Earth Case

Abstract

A general formulation for the calculation of the influence of the earth return path on the impedances and the admittances of underground multiconductor power cable arrangements is presented in this paper. The expressions for the self and mutual earth correction terms are derived by a rigorous solution of the electromagnetic-field equations. The involved semiinfinite integrals are calculated by using a suitable numerical integration technique. The propagation characteristics of a single insulated conductor and of a typical three-phase single-core cable arrangement are investigated and are compared to the corresponding ones obtained by other approaches. Finally, the cable parameters calculated by the proposed method are used in a simulation of a fast transient in a three-phase single-core cable.Index Terms-Earth return admittance, earth return impedance, electromagnetic transients, power cable modeling.

Analysis of ground return impedance calculation methods for modeling of underground cables for lightning studies

“…Several researchers proposed solution methods for the direct numerical evaluation of the Pollaczek integral [21][22][23][24][25]. These methods require a considerably higher amount of computations in comparison to the other approximation methods mentioned earlier.…”

Effect of ground return path on partial discharge signal propagation along single-core and three-core power cables

“…Similar to (3), the modal variables are derived: YZT I is diagonal with eigenvalues as matrix components which are related to the modal parameters as (6)(7)(8).…”

“…Sunde [7] further developed the model from Pollaczek by including the influence of the earth permittivity to the earth return impedances. Papadopoulos and his colleagues claimed that previous earth impedance models are limited to the low frequency range because they all neglect the influence of the earth to the shunt admittance [8]. These authors gave general expressions to calculate the effect of earth return impedance on underground single-core power cables by utilizing numerical integration techniques [21].…”

“…Figure A3 shows the geometric configuration of a single-core underground cable. The self-earth impedance can be evaluated according to [8] by…”

“…However, earth is part of the transmission line model. The earth impedance itself has been studied by many researchers [5][6][7][8].…”