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Reference Number NIA_NGTO013
Title Predicting Vibration Fatigue for Overhead Line Conductor Systems
Status Completed
Energy Categories Other Cross-Cutting Technologies or Research 100%;
Research Types Applied Research and Development 100%
Science and Technology Fields PHYSICAL SCIENCES AND MATHEMATICS (Metallurgy and Materials) 50%;
UKERC Cross Cutting Characterisation Not Cross-cutting 100%
Principal Investigator Project Contact
No email address given
National Grid Electricity Transmission
Award Type Network Innovation Allowance
Funding Source Ofgem
Start Date 01 July 2018
End Date 01 July 2019
Duration ENA months
Total Grant Value £89,000
Industrial Sectors Power
Region London
Programme Network Innovation Allowance
Investigators Principal Investigator Project Contact , National Grid Electricity Transmission (100.000%)
  Industrial Collaborator Project Contact , National Grid plc (0.000%)
Web Site
Objectives Finite Element Analyses of vibrations on complex structures will be used to quantify the vibration amplitudes against existing simple experimental measurements available for common conductors, as well as GAP and ACCC HTLS conductors (from data already available) and other available data from NG.This initial approach aims to verify that a tool to quantify the fatigue of complex conductor structures (and differentiate among the different conductors) based on the vibrations is possible. This preliminary/feasibility study could, later on, be combined with experimental measurements in a small test-bed to capture the effect of different operating temperatures and tensions to validate and finalise a more advanced tool that can be used to predict conductor (single and bundles) life expectancy due to vibration fatigue. Review the current modeling practices and identify the cases for which existing (CIGRE) calculations are not adequate (have a significant error) and thus not appropriate to be implemented on all conductor types. Develop a preliminary tool that can capture the structural effect of conductors and allow the effect of structural differences to be quantified. Quantify also the error (in relation/comparison to the current practice) and its significance. Perform Finite Element Analyses using COMSOL on a single conductor and a twin bundle to identify the complexity, computer resources, and time required for modelling conductor vibrations and compare Finite Element Analysis (FEA results with current CIGRE standard calculations (used currently by the industry). To demonstrate that conductor structure and stranding geometry affect vibration fatigue (for conductors and bundles) and develop a preliminary computational tool to quantify it.To identify the properties that make some conductors more immune to vibrations and correlate these with any benefits on increasing overhead line systems power flows.
Abstract Conductor vibrations are one of the most common reasons for conductor fatigue and failures. CIGRE has highlighted that for ACSR (Aluminum Conductor Steel Reinforced) there is uncertainty in relation to self-damping since it depends on the tension shared between aluminum strands and the core at different temperatures. This uncertainty is even more prominent with High Temperature Low Sag (HTLS) conductors. Furthermore, the current methods for quantifying vibration fatigue are based on beam theory (which is valid only for homogeneous conductors) which ignores the properties of the interlayers (e.g., trapezoidal vs. round strands). Past work indicated that the natural frequency under the assumption of the conductor with isotropic properties (i.e. solid homogeneous beam) results in more than 40% error on vibration effects when compared to the composite (sandwich beams) conductor assumption. Currently, there is no existing method to calculate the fatigue of composite (bimetallic, bi-material) conductors and there is also a lack of metrics (apart bending stress) that can be associated with the effect of vibrations on conductor and conductor bundles condition (life expectancy and fatigue).As a result, there are high levels of uncertainty in the expected life of these assets. Better understanding vibration fatigue will allow for more accurate assessment of life expectancy.
Publications (none)
Final Report (none)
Added to Database 02/12/22