Modeling the overhead line vulnerability to combined wind and snow loads for resilience assessment studies

Extreme weather events are a major concern for Transmission System Operators (TSOs) because of their increasing frequency and disruptive effects on system infrastructure and load supply. The assessment of component vulnerability to natural threats is essential for an accurate evaluation of power system resilience. However this task is very challenging also due to the interactions among different threats: models should be sufficiently complete to take this complexity into account, but also practical enough to be applied to large power systems. A notable example concerns snow and wind, which determine combined actions both directly on the infrastructure of an overhead line (OHL) and indirectly on the environment (such as trees) around the line path. The paper presents an analytical model of the vulnerability of OHL to the combined actions of snow and wind, assuring a good tradeoff between accuracy and tractability. Simulations performed on a line from an area of the Italian transmission grid show the ability of the model to account for the combinations of snow and wind induced actions both on the OHL infrastructure and on the environment interfering with the OHL.