Application of Non-Gapped Line Surge Arresters to the 150 kV Overhead Lines of Rhodes: An Investigation through ATP-EMTP Simulations

The application of non-gapped line surge arresters (NGLAs) to the 150 kV double-circuit overhead lines of the electrical network of Rhodes island in southeastern Aegean Sea, Greece, is investigated through ATP-EMTP simulations. Several NGLA installation configurations are studied considering the power frequency tower ground resistance and AC voltage phase angle as parameters. The simulated scenarios include lightning strikes to shield wire, as well as to phase conductors (shielding failure). The improvement of the lightning performance of an 150 kV line is quantified. The current flowing through the NGLAs and the corresponding absorbed energy are computed. The energy stress of the NGLAs due to shielding failure is more severe as compared with the case of lightning strike to the shield wire; this holds even for the highest tower ground resistance of 200 Ω considered in this study. A significant improvement of the lightning performance of the investigated 150 kV double-circuit overhead line requires the installation of at least three NGLAs per tower, protecting one of the two circuits. For the relatively low tower ground resistance of this line (10 Ω), this configuration prevents backflashover of both circuits as well. However, for higher ground resistance values six NGLAs per tower are required to completely eliminate backflashover.