Local System Modeling Method for Resilience Assessment of Overhead Power Distribution System under Strong Winds

Abstract

During extreme weather events, such as hurricanes or major winter snowstorms, power distribution systems, such as the overhead power distribution systems consisting of wood poles and power wires, would encounter failures that can bring massive power outages. Daily lives for communities are significantly affected by the interruptions of the regular service of power distributions. Fragility assessments of pole-wire systems under high wind loads have been carried out before, either using physics-based structural analysis methods or data-driven methods. However, fragility analyses of the entire pole-wire system are still challenging due to the lack of detailed information for dimensions, materials, soil conditions of pole-wire systems, the inconsistent wind loads applied on the systems at different geographic locations, and high computational costs. In the present study, a new local system modeling method considering the effects of neighboring spans for the resilience assessment of overhead power distribution systems under strong winds is proposed. The effects of neighboring spans are investigated to predict the failure probability of pole-wire systems with lower computational costs. Soil springs are applied to model the boundary support of poles to provide a more reliable estimation of the structural behaviors under large wind loads. Various simple pole-wire systems with different numbers of poles are studied to investigate the effects of neighboring spans. The number of neighboring spans that might affect the structural behaviors of the studied poles is investigated. The effects of lateral lines on the structural behaviors of the studied poles are also investigated. Based on the results, a case study is conducted to validate the accuracy of the proposed method. The reliability of a hypothetical pole-wire system calculated by the structural analysis method and the proposed method is compared. The accuracy of the proposed method is validated. Additionally, the effects of the degradation of neighboring spans on the structural behaviors of the studied poles are studied. For a local region with complex geographic terrain, wind loads applied on a pole-wire system could vary at different locations. Fragility curves of poles calculated with the proposed method under different wind directions are obtained to include the wind direction effects. The proposed method could help consider interactions between individual pole nodes with acceptable computational costs.