Transient analysis on overhead transmission line considering the frequency dependent soil representation

Abstract

This paper presents a transient study, analyzing the frequency-domain response and the time-domain response of overhead transmission line (TL) with the longitudinal and transversal parameters represented by models that take into account the influence of the earth's parameters frequency dependence. Usually, between 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> Hz and 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> Hz the earth's conductivity may have the same order of magnitude as the product of the signal angular frequency (ω) by the dielectric constant (ε <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> ) due to the dependence of these parameters with frequency. Therefore, the low frequency assumptions traditionally used - the soil conductivity considered as constant and ω.ε <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> nil - can lead to incorrect models that does not adequately represent the transmission line's transient response. A practical example it is presented through a time-domain single-phase switching test (SFST) in order to compare the TL transient response with the frequency dependence soil representation and the regular representation with constant conductivity in the PSCAD program.