Influência da resistividade elétrica do solo na impedância longitudinal de sequência por unidade de comprimento em linha de transmissão aérea

Abstract

Overhead transmission lines make up a vital part of the electrical power system, which is responsible for generating, transmitting and distributing large amounts of electrical energy, necessary for the development of any nation. Brazil is a country with continental dimensions, having in its composition different climates and vegetation, factors that influence the formation of the soil and, therefore, the value of its electrical resistivity. With this, it becomes necessary to identify the importance of modeling the soil as a conducting plane with finite resistivity, analyzing the relationship between different soil resistivities and the unit longitudinal electrical parameters, decomposed into sequence components, also known as modal components, using the complex image method. In this work, a calculation routine was developed, in MATLAB® language, to reproduce the matrix calculation of the electrical parameters of the transmission line, with data from a real 440 kV line, from the primitive matrix to the sequence impedances. The results were compared with the data obtained in the PSCAD/EMTDC® software, separated as resistance and inductance per unit of length, presented in the form of tables and graphs. These data show that the consideration of the real ground has no negligible influence on the positive sequence impedance, however, it drastically influences the zero-sequence impedance, in a more impactful way when ignored and produces considerable error within the analyzed resistivities.