Fragility models of electrical conductors in power transmission networks subjected to hurricanes

Power transmission conductors work as links in power transmission system. They allow the bulk transportation of energy between power plants and substations. A large number of these conductors may fail when subjected to hurricanes. Failure of these conductors may result in significant disruption in the power network and millions of dollars of replacement cost. This paper presents a framework for the development of fragility models of the transmission conductors. The framework considers the uncertainties in the wind turbulence and conductor capacity. The modal superposition method has been used to model the mechanical response of the conductors efficiently, and is validated by nonlinear finite element analysis. The first order reliability method has been implemented to capture the low failure probability of a single conductor with sufficient accuracy as confirmed by Monte Carlo simulation. The results of this study show that the failure probability of the conductors increases significantly once the wind speed reaches a certain critical value. The wind direction and span length have large influence on the failure probability. Therefore, the variability of span lengths over the transmission network has a substantial effect on the overall system failure. The fragility model provided in this research constitutes a major component for risk assessment of power transmission networks against hurricane hazards. It can be used to help engineers gain fundamental insights on the mechanical and probabilistic performance of power transmission conductors.