Estudo Inicial a Respeito de Sobretensões em Linhas de Transmissão Considerando o Efeito da Frequência Sobre os Parâmetros do Solo
Keywords: Electromagnetic transient, frequency-dependent soils, transmission lines, ground-return impedance, ground-return admittance
AbstractIn order to compute the electromagnetic transients in power systems adequately, several papers in the literature have proposed different approaches to properly model the ground by its frequency-dependent (FD) soil parameters (conductivity and permittivity). This article presents a brief study on how to simulate electromagnetic transients generated on single- phase transmission line (TL) subjected to slow- and fast-front disturbances. For this analysis, a summary of 8 FD soil models developed in the literature, discussing their conditions and variations, is presented. Then, the formulations of each model are included in the calculation of the longitudinal impedance and the transversal admittance of a certain TL where the impact of the FD soil models are discussed. A comparison between the transient responses obtained with a TL located above a ground considering its frequency-constant electrical parameters with those computed with different FD soil models is carried out. Results indicate that a significant modification on the transient responses characterized by reduced peaks and shifted waveforms is obtained when the FD soil models are considered for the analysis.