Contrôle passif non linéaire du galop sur les lignes aériennes de transport d'énergie
Bibliographic record
Abstract
This thesis presents advancements made in the research project titled: "Nonlinear passive control of galloping on overhead transmission lines." This study focuses on galloping oscillations in the conductors of overhead power transmission lines. This phenomenon occurs due to interactions of effects of icing around the cable (and modification of the profile of the cable) which may produce aerodynamics instabilities. The galloping is mainly related to low frequency (ranging from 0.08 Hz to 3 Hz) and high amplitude vibrations. This phenomenon can cause severe damage to the cables, such as short circuits and cable breakages. Certain devices, such as interphase spacers and detuning pendulums, help to mitigate the consequences of galloping. The aim of this project is to investigate the possibility of nonlinear passive control of galloping oscillations. The goal is to model the coupling of a transmission line cable subjected to galloping instability with a nonlinear passive absorber known as a Nonlinear Energy Sink (NES). This aims to evaluate the efficiencies of the NES in controlling galloping vibrations on power transmission lines. First of all, a simplified linear beam model with elastic boundary conditions is presented. This model enables local study of the coupling between a transmission line cable subjected to galloping instability and a nonlinear absorber. This initial step introduces an analytical modeling of the aerodynamic force based on a quasi-static motion assumption. Then, a more comprehensive analytical model which takes into account the geometric nonlinearities of a power transmission line span is articulated. This model also considers a self-excited aerodynamic force. The analytical results of the nonlinear dynamics of one span of the considered system are compared with numerous finite element results. This analytical model is also compared with experimental data by matching bifurcation diagrams and galloping observations collected by the Hydro-Québec research institute. This model serves as a design tool for a nonlinear absorber to control galloping oscillations of a mode of an overhead power transmission line span. Finally, a finite element modeling of a transmission line span coupled with a nonlinear absorber is performed. This modeling considers the interaction between the wind and the cable covered with an ice layer. Unlike the analytical model, this finite element model is not designed as a dimensioning tool but has the advantage of fewer simplifying assumptions than the analytical model. It allows studying inter-modal energy transfers that can occur during galloping oscillations.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.009 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".