Influence of accurate soil representation for transmission-line parameters: Analyses based on Carson´s modified formulations

In this paper the influence of earth´s conductivity and permittivity frequency dependence are evaluated when calculating transversal and longitudinal transmission lines´ parameters directly from numerical integration of Carson´s modified expressions. As an example of the importance of properly considering the frequency-dependent soil model, an actual 440 kV single three-phase transmission-line was represented, comparing the longitudinal and transversal parameters considering the earth´s conductivity and permittivity frequency dependence soil model in relation to the common soil representation with a constant conductivity and permittivity that can be neglected assuming a low frequency approximation.