Bayesian Approach for Typhoon-Induced Fragility Analysis of Real Overhead Transmission Lines

Failure accidents of transmission lines due to excessive wind-induced displacements pose a serious threat to the operational stability and security of the electric power grid. A Bayesian approach is proposed to assess the discharge failure probability of overhead transmission lines under typhoon hazards. The Bayesian approach is capable of combining the prior information in the design stage and the full-scale measurement data in the operational stage together to determine the real performance of the tower-line system. By integrating the procedures of the model updating, modal identification, and multiscale wind field simulation in a unified Bayesian framework, the uncertainties of the structural parameters and wind load conditions are reduced and the fragility results are refined according to the updated data and parameters. Based on full-scale measurement data collected during the two strong typhoons Talim (1718) and Kong-rey (1825), the wind-induced fragility of a full-scale transmission line is updated sequentially using the proposed approach. The fragility results show that the failure probability may be underestimated in the design stage, which introduces potential risks in the long-term operation of transmission lines.