Evaluation of lightning protection of unshielded 132kV overhead lines using surge arresters

Abstract

The usual lightning protection of high volt-age overhead lines is the usage of groundwires. In some cases, they cannot be used. This paper evaluates the effectiveness of different alternative protection schemes using surge arresters for a 132kV unshielded overhead line. The protection schemes are: a surge arrester at each conductor and tower, a surge arresters only at the central conductor and every tower (the configuration studied has the central conductor higher than lateral ones at therefore acts as a shield wire) and a surge arrester at each conductor and one out of two towers. The last two protective schemes are consid-ered due to economic reasons. Number of annual flashovers in a 100km line with the different protec-tion schemes is computed following IEEE recommen-dations. Direct, induced and back flashovers are con-sidered. Over-voltages are computed using the ATP software package, distinguishing between tower, cen-tral conductor and lateral conductor lightning strokes. Conclusions are presented about the effectiveness of each protective scheme.