A Concept for Overhead Transmission Line Performance Evaluation toward Lightning Strikes

Abstract

According to the historical data, most overhead transmission line (OHL) fault was caused by lightning strikes. However, the evaluation of OHL performance toward lightning strikes in PT PLN (Persero) was commonly performed by gathering the number of recorded faults without any value as a reference. This paper explains a concept for OHL performance evaluation toward lightning using the Total Outage Rate (TOR) method. TOR value was obtained by calculating the probability of flashover (shielding failure flashover/SFFOR and back flashover/BFOR) based on OHL design data and lightning data. According to the analysis, the evaluated 150 kV OHL historical fault was 3.26 fault/year/100 km which is lower than the calculated TOR (6.01 flashover/year/100 km). Therefore, this OHL doesn't need any improvement toward lightning performance (i.e., installing Transmission Line Arrester, unbalancing insulator). A brief framework of this evaluation method is presented as a reference for OHL sorting. The result of variation toward several parameters in OHL design showed that a higher value of tower footing resistance, a bigger shielding angle, and a lower value of the insulator's BIL give a higher TOR value.