Effects of Adjacent Spans and Correlated Failure Events on System-Level Hurricane Reliability of Power Distribution Lines

Past performance of distribution networks against hurricanes has highlighted the high vulnerability of these systems in electric power networks and the need for their reliability assessment for risk-informed decision-making purposes. A network level reliability analysis would require the estimation of reliability of line segments between key switches in the network. Former reliability studies, however, are based on a number of limiting assumptions. These include assuming independent mechanistic behavior of spans in a line segment during strong winds and statistical independence of failure events of components in a line. Due to correlations in wind loadings on the poles, environmental conditions that affect the decay rate of the poles, and structural properties of the poles, failures of poles are expected to be correlated events. This paper investigates the effects of these factors on the hurricane reliability of power distribution lines. Couplings in the wind performance of adjacent spans are incorporated here properly through an equivalent boundary model. Moreover, a multiscale matrix-based method is adopted to efficiently assess system reliability of distribution lines considering correlations in the failure events of line components. Numerical results indicate that couplings and statistical correlations have a considerable impact on the reliability of distribution systems.