Estudo do desempenho de linhas de transmissão sob ação de descargas atmosféricas

Abstract

This work was essentially dedicated to the evaluation the performance of transmission lines when submitted to the action of lightning. This phenomenon is very random and, especially, when the impact occurs directly on the transmission line, constitutes the main source of outages. Thus, it is necessary to complete understanding of the mechanisms that determine these outages. Emphasis was given to the performance of LTs with nominal voltage levels from 138kV. Thus, was presented a specific analysis of the main mechanisms associated with outages because the incidence of lightning, in three situations: directly in the phase conductor, next to the phase conductor and directly into the cable shield or metallic structure. All these mechanisms can significantly influence the outages rates in transmission lines with voltage levels from 138kV. Based on these mechanisms was performed an evaluation of the efficiency of traditional and unconventional practices, from previous studies to improve the performance of transmission lines in the face of lightning, to reduce the outages rates. Finally, were presented the results obtained through simulations using the computation plattaform Alternative Transients Program ATP. Was considered a typical configuration of transmission lines and two forms of wave current: first discharge and subsequent discharge, to evaluate the overvoltage caused the lines. Then, an evaluation of practices for reducing the number of outages was done.