An investigation into extreme-weather-caused transmission line unavailability

One of the primary causes of major transmission line outages is extreme weather conditions particularly lightning, wind and conductor icing (e.g., Quebec, U.S. ice storms of 1998). The statistical results of a detailed analysis of an Alberta provincial utility´s transmission line outage data base and Alberta Environmental Service weather data bases over a 20 year period are investigated in this paper. The analysis reveals the significance of the geographical location of the transmission lines and their frequency of outages. The paper also reveals that the number of transmission line outages is not necessarily proportional to the physical length of the line for many transmission lines which contradict may publish methodologies. The paper provides the basic framework for constructing advanced probabilistic reliability models of transmission line networks (e.g., Markov models and Monte Carlo simulation models) based on the historical Canadian Electricity Association´s utility equipment reliability data base [1] and the environmental service weather data bases.