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 optimize 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 paper 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.

Network reliability framework integrating demand response and flexible OHL ratings

“…Equation (13) shows the minimum and maximum limits for factor L,j . The values min and max are selected based on the criticality of line ageing.…”

“…Till now, there is very limited literature combining reliability benefits and network ageing risks resulted from EL and PLR [9,10]. Although a few studies capture the ageing risks accompanied by the EL operation of OHLs [11][12][13], they fail to define proper economic solutions for minimising those risks.…”

Determination of the power transmission line ageing failure probability due to the impact of forest fire

“…The main factor causing ageing of power transmission line is high operating temperature [20]. To calculate the ageing failure probability under forest fire, real-time line temperature should be obtained first.…”

“…After obtaining the line temperature, the ageing failure probability can be calculated by (20). Simulation results of ageing Fig.…”

Transient Temperature Calculation and Multi-Parameter Thermal Protection of Overhead Transmission Lines Based on an Equivalent Thermal Network

“…The electrical and mechanical properties, strength loss, and sagging of overhead transmission lines during overloading are influenced by conductor temperature and overload duration [8][9][10]. The conductor temperature can be a more accurate reflection of the safety condition of transmission lines than current.…”