Assessing a Health Index Algorithm for High Voltage Overhead Power Lines

High Voltage (HV) overhead power lines are complex systems of interconnected elements used to move huge amounts of electrical energy over national and international distances. Elements of overhead power lines are towers, insulator chains, bare conductors and accessories. They are designed according to the rated values of current, voltage and temperature, in order to satisfy an expected life, which is typically estimated in 50 years. As a consequence of the stresses determined by the operating conditions and the environment external agents, all the elements of the power lines are subject to ageing. Degradation mechanisms reduce power line useful life time, thus producing conditions for fault occurrences. Therefore, actually, models for assessing ageing and residual life of power line elements are topics of great interest. In this paper, an Health Index (HI) procedure for power conductors is proposed. The procedure assesses the mechanical degradation mechanisms acting on the energy carrier as a function of internal and external stress factors. Basing on the IEC Standards, a strength-stress model is formulated. Numerical simulations give evidence to the HI curves obtained as result of the proposed ageing model.