An efficient nonlinear method for cascading failure analysis and reliability assessment of power distribution lines under wind hazard

Abstract

The weakest poles in a power distribution line (PDL) will overturn first and then cause additional impacts on adjacent poles through wires, which may trigger catastrophic cascading failures. This paper aims to develop a more accurate and efficient approach to support risk assessment of cascading failures for PDLs under wind hazards. The failure propagation equation is first proposed, which is a nonlinear method for solving tensions of a multi-span PDL considering the pulling effect of failed poles; The vertical and horizontal overturning angles of failed poles are determined, and their impact on cascading failures is investigated. Regarding the cascading effect, the structural fragility is estimated using Monte Carlo method, and the failure probability is further obtained considering the joint distribution of wind speed and direction. Finally, an innovative probability-based critical collapse curve, featured by optimizing structural parameters including horizontal span and operating tension, is proposed to reduce cascading failure risks. Compared with previous works, the proposed method exhibits unique advantages in terms of accuracy; Ignoring the influence of overturning angle overestimates additional tensions; The failure probability significantly increases after considering the cascading effect. The proposed method possesses extensive application prospects in performance evaluation and anti-continuous collapse design of PDLs.