Lightning caused outages in the Austrian Power Grid transmission line network

Austria is one of the European countries with relatively high lightning activity [1] and lightning is a main cause of transmission line outages. In this presentation we have analyzed in detail lightning caused outages in the grid of the Austrian transmission system operator Austrian Power Grid (APG). 222 outage related lightning flashes were identified in the database of the Austrian lightning location system ALDIS as these flashes were located within a corridor of ±1 km along the considered lines and within a time window of ±1 second of the recorded outage time. These 222 flashes (203 of negative and 19 of positive polarity) are analyzed in terms of their local occurrence along the transmission lines and their peak currents. Tower footing resistances, which are affecting the occurrence of back flashover failures, were found to be log-normal distributed with a median of 4.4 Ω and a σ_ln = 1.1. Median peak current of negative and positive flashes causing transmission line outages is -11.3 kA and 37.9 kA, respectively, and median distance of flash locations to the line is 322 m.