An Improved Approach for the Calculation of the Transient Ground Resistance Matrix of Multiconductor Lines

The general integral expressions for the elements of the ground impedance matrix do not have an analytical inverse transform in the time domain. Therefore, the ground transient resistance of a multiconductor line is commonly evaluated in the time domain by means of approximated expressions in order to avoid the numerical inverse fast Fourier transform burden. In this paper, we propose a new analytical approach for calculating the transient ground resistance in the time domain that stands on the very accurate Sunde logarithmic expression for the ground impedance matrix of an overhead multiconductor line. The proposed analytical approach is adopted for calculating lightning induced voltages in a multiconductor overhead line. The results show that the proposed analytical formula is in perfect agreement with the numerical inverse Fourier transform of the general Sunde expression and, therefore, is more accurate than the approximated expressions available in the literature.