Análise comparativa de correntes de curto-circuito utilizando o método das componentes simétricas e o método das componentes de fase.

Abstract

Usually, in short-circuit analysis, transmission lines are assumed to be ideally transposed without addressing the errors that this assumption may cause. This work presents a comparison of the values obtained for phase to ground fault current in transmission lines, using the symmetrical components method and the phase coordinates method. The study is carried out in steady-state for a single and a double circuit transmission lines. The calculation of parameters and short-circuit simulations are performed with the ATP (Alternative Transients Program). Three situations are addressed: ideally transposed line, actual scheme transposed line and untransposed line. The Fortescue transformation matrix is applied to define the ideally transposed line parameters, characterizing the analysis using symmetrical component method. For phase coordinates modeling, each line section between transposition towers is represented by a PI circuit with lumped components. The actual transposition scheme is taken into account by interchanging each phase conductor position at the transposition towers, in such way that, on the average, along the line each phase conductor occupies the position of the remaining phase conductors. The values of fault current at several points along the line are obtained for each case and compared against.