Cálculo de impedâncias e admitâncias internas de cabos isolados empregando modelos analíticos e elementos finitos

Abstract

This paper presents the calculation of internal impedances and admittances by Finite Element Method, varying cable configurations and material. The results obtained by the numerical formulations were compared with those obtained by analytical formulations between 0.1 Hz and 1 MHz. Initially, a single-phase case was analyzed and from this, new cases were implemented, considering three-phase systems surrounded by a common pipe with the purpose of analyzing the influence of the arrangement of the power veins on the internal parameter calculations. It was observed that the closer the sheeth is to the armor, the greater its own capacitance and resistance variations occur for high frequencies. For multifilament cable cases, it was observed that the insertion of a semiconductor layer has little influence on the impedance calculations, but causes an increase in capacitance values. Moreover, it was found that an equivalent cable with solid conductor and area equal to the sum of the filament areas has a maximum percentage difference for capacitance less than 17%, but for resistance has discrepancies at high frequencies and for inductances has discrepancies for low frequencies. At the end, the contribution of a communication cable in the impedance and capacitance matrices was calculated.