Analysis of Lightning Shielding Design of High Voltage Overhead Lines for Transelec

Transelec is the leading power transmission company in Chile, with nearly 10.000 kilometers of power transmission lines and nearly sixty 500 kV and 220 kV substations in the Central Interconnected System (SIC) power grid and the Great North  Interconnected System (SING) power grid. Due to the geographic and climatic diversity of the territory covered by the transmission lines owned by Transelec, these are exposed to frequent faults and outages produced by lightning strikes affecting the operation of the whole interconnected system. Worried about the issue, Transelec wanted to analyze the current state of lightning shielding of their overhead lines. Unfortunately, Chile does not have information about lightning activity over his territory, therefore calculation of the ground flash density GFD was carried out base on Word Wide Lightning Location Network (WWLLN) database. Five overhead lines were analyzed based on failures reports and based on GFD maps, taking into account overhead lines with high outage rates and high GFD.  Lightning shielding was analyzed based on electrogeometric method taking into account landform and catenary. From the analysis, it was concluded which section or sections of overhead line show the highest likelihood of shielding failure for every overhead line. To sum up, results were compared with failures reports in order to stablish a relationship between them and lightning activity in those areas.