Ferramenta computacional para cálculo da impedância série e capacitância de linhas aéreas de transmissão

Abstract

The calculation of the parameters of overhead transmission lines used in studies of shortcircuit is difficult to develop, requiring the assistance of computer programs. The software available in the market are expensive and not intuitive in its use. Thus, this work presents the development of a JAVA SE application denominated LTCalc for calculating the series impedance and capacitance for overhead transmission lines. At first, the required data for the study is presented, as well as its appropriate treatment. The process for calculating the self and mutual impedances that compose the impedance matrix is demonstrated, taking into account Carson's method for correcting the effect of soil. It will also be exposed the methodology of constructing Maxwell's potential matrix, and its inverse matrix, which is the line capacitance matrix. Methods are proposed to reduce the matrix considering the effect of grounded wires, bundled conductors and double circuit lines, and also applying the symmetrical components transformation to the matrix. The software operation sequence for performing an analysis is explained, as well as its corresponding ATP's Line Constant parameter. A case study of a 500 kV line was done, detailing its calculation process and execution in LTCalc, and ATP's Line Constant sub-routine was used to validate LTCalc's results.