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

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 10³ Hz and 10⁶ 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_g) 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_g 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.