Probabilistic analysis of weather related loads on overhead transmission lines in Ontario, Canada

Design and installation of transmission lines are considerable economic undertakings for electric utility companies. The common approach to the design of transmission lines has been by deterministic methods. However, the designers are now considering the use of probabilistic methods to improve the reliability and economics of new transmission lines. The major requirements for applying the probabilistic methods are well established load and strength databases. A program developed previously by the authors (1988) has been used to estimate weather related loads needed for reliability based design of transmission lines. Statistical parameters such as mean, coefficient of variation and Gumbel extreme value coefficients for wind, ice and wind-on-ice loads have been calculated for 30 weather stations in Ontario. Also discussed are the combined occurrences of wind and ice loads on conductors, which would be useful in the probabilistic analysis of certain type of transmission line problems