2015 CSCE Annual Conference Regina - Building on our Growth Opportunities

2015 CSCE Annual Conference Regina - Building on our Growth Opportunities Conference

Effect of the design resistance of towers on the extent of transmission line cascading failures

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Mr. Sébastien Langlois, Université de Sherbrooke (Presenter)
Mr. Oussama Lamine Naouali, Université de Sherbrooke
Dr. Frédéric Légeron, Université de Sherbrooke

Transmission line structures may suffer catastrophic losses when cascading failures occur. These events are caused by dynamic loads very often related to the sudden ruin of conductors or other mechanical equipment. One strategy that is commonly used to mitigate the risks of large losses is the insertion of more robust, anti-cascading supports at specific locations along the line, for example at every 10 towers. This strategy limits the maximum number of failed supports. However, to further reduce financial losses, it would be interesting to better control the extent of these events. On the other hand, many authors have developed numerical models to reproduce the dynamic behavior of transmission lines subject to a broken conductor event. This paper studies, using a non-linear time history finite element model, the possibility to limit the extent of cascading failures simply by designing the towers to resist a certain portion of the dynamic load caused by a broken conductor. The model is first validated with existing small-scale experiments. Then, a parametric study is performed on a typical line section composed of tubular steel towers to provide graphs for the number of supports affected as a function of the tower resistance. Variables studied include the following: conductor mechanical tension, span length, and insulator length. The results of this study show that the numerical method and the strategy presented could allow transmission line designers to make decisions of their tower resistance that could limit the extent of possible cascading failures to a certain desired number of towers.