Parametrized fragility, failure analysis and cost-effectively strengthening of electrical power distribution system under ice and concurrent wind hazards

In the past decades, the increasing frequency and severity of winter storms due to climate change have revealed the vulnerability of power systems against such events. This study aims to investigate the impact of ice and concurrent wind hazards on power systems by proposing a set of parametrized fragility functions for utility poles and conductors, and then applying them to system failure analysis and cost-effectively strengthening. The fragility model is generated by logistic regression to estimate the failure probability of poles and conductors as a function of hazard and structural characteristics. Applying proposed functions, system failure analysis is performed using IEEE123 testbed in four cities with various hazard characteristics. The results show that wind speed significantly affects pole rupture, while extreme ice and wind combination influences conductor breakage. Meanwhile, even minor structural failure leads to severe outages. Moreover, the risk-based Expected Outage Reduction (EOR) is calculated with developed fragility models as pole replacement ranking index. By comparing different replacement strategies, the 70-year system performance can be cost-effectively optimized by risk-based pole ranking and replacement pace and timing. Overall, the models and applications presented in this paper serve as a critical part of power system resilience analysis against winter-related hazards.