Overhead line design considerations for conductor creep mitigation

Abstract

Utilities are continuously investigating methods to economically reinforce their overhead line (OHL) networks by reconductoring with larger conductors or with novel high-temperature low-sag (HTLS) conductor technologies. To further optimise the OHL design, conductor creep ageing is calculated and mitigated at installation, which economically improves an OHLs’ performance. An already established methodology is used to investigate common and HTLS conductors ageing effect on sag and tension in order to highlight the benefits and risks that could result from existing creep mitigation methods particularly on HTLS conductors. The study aims to identify the impact of important design factors such as ice loading and emergency operation events and their frequency of occurrence on creep mitigation as well as to highlight the creep variation of the same materials used particularly on different HTLS conductors. The analysis presented here indicates that pre-tensioning could be more beneficial on soft aluminium HTLS conductors while over-tensioning can result in extensive durations of conductor over-stressing on steel supported and Gap-type conductors. Furthermore, the conductor technology majorly affects the creep of steel core which cannot be considered always as zero. The accuracy of the methodology is also re-validated using recent experimental data from Gap conductor.