Active Vibration Control of WTG

Aktiv vibrationskontrol af WTG

Bau, Alexander John ; Ochelka, Thomas Johannsen

4. term

Electro-Mechanical System Design, Master

2026

2026-05-29

53

Wind turbine gearboxes experience high‑frequency twisting (torsional) vibrations caused by the repeated engagement of gear teeth (gear meshing). Over time, these vibrations can increase wear and reduce efficiency. This thesis examines how to model these gear‑mesh vibrations and reduce them by actively using the generator torque to counteract the motion. We analyze measured vibration data in both the frequency domain and the order domain (relative to rotational speed) to identify the main excitation sources in a two‑stage planetary gearbox. Guided by these findings, we build a simplified single‑degree‑of‑freedom torsional model that represents the dominant twisting mode. The model uses a grey‑box approach that combines basic physics with data. Its parameters are fitted to operational data using nonlinear least‑squares optimization, and time‑varying excitation gains are estimated with a sliding‑window method (calculations over short intervals to track changes). The model reproduces the key dynamics, including resonance and how vibration levels vary with speed and load. Two control strategies are evaluated in simulation. Harmonic Feedforward (HFF) applies a cancelling torque at the gear‑mesh frequency. Adaptive Harmonic Feedforward adjusts this cancellation based on the measured vibration level, so it can cope with changing operating conditions. In the simulations, both methods reduce vibration under normal conditions, and the adaptive approach performs better when speed and load vary. Overall, the results indicate that active generator‑torque control is a useful way to mitigate gear‑mesh vibrations in wind turbine gearboxes.

Vindmøllers gearkasser udsættes for højfrekvente vridningsvibrationer (torsion), når tandhjulenes tænder gentagne gange griber ind. Med tiden kan sådanne vibrationer øge slitagen og sænke effektiviteten. Specialet undersøger, hvordan disse tandindgrebs‑vibrationer kan modelleres og dæmpes ved aktivt at bruge generatorens moment til at modvirke bevægelsen. Vi analyserer målte vibrationsdata i både frekvensdomænet og ordre‑domænet (i forhold til omdrejningstal) for at finde de vigtigste excitationer i et to‑trins planetgear. På den baggrund opbygges en forenklet torsionsmodel med én dominerende frihedsgrad, som beskriver hovedvridningen. Modellen er en grå‑boks tilgang, der kombinerer grundlæggende fysik med data. Modellens parametre tilpasses driftsdata med ikke‑lineær mindste‑kvadraters optimering, og tidsvarierende excitationsforstærkninger estimeres med en glidende vindue‑metode (beregninger over korte intervaller for at følge ændringer). Modellen gengiver de væsentlige dynamiske forhold, herunder resonans og hvordan vibrationsniveauer ændrer sig med hastighed og last. To styringsstrategier vurderes i simulation. Harmonisk feedforward (HFF) påfører et modvirkende moment ved tandindgrebsfrekvensen. Adaptiv harmonisk feedforward justerer denne kompensation ud fra det målte vibrationsniveau og kan derfor håndtere skiftende driftsforhold. I simulationerne reducerer begge metoder vibrationer under normale forhold, og den adaptive tilgang klarer sig bedst, når hastighed og last varierer. Samlet set peger resultaterne på, at aktiv styring af generatorens moment er en nyttig måde at dæmpe tandindgrebs‑vibrationer i vindmøllers gearkasser.

[This apstract has been rewritten with the help of AI based on the project's original abstract]

Vibrationer ; Kontrol ; Gearboks ; Vindmølle ; Planet gearboks ; FFT

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