Earth conductivity and permittivity data measurements: Influence in transmission line transient performance

In this work some procedures to measure and model soil electromagnetic behavior in frequency domain are presented. The soil samples were collected at Cachoeira Paulista, Brazil, southeastern region (22°41.2′S, 44°59.0′W). The proposed model takes into account the earth conductivity and permittivity frequency dependence. Some procedures to reduce noise signals in the field measurement values are presented. The parameters of an actual 440 kV single three-phase transmission line were evaluated in frequency domain (considering the proposed soil model and the common representation with a constant conductivity and no permittivity), such as longitudinal line parameters, attenuation factor, phase velocity and transfer function. It was possible to identify regions where not considering the proposed model could result in severe error.