Fatigue reduction in floating offshore wind turbines using tuned mass dampers - A modelling approach in the frequency domain
| Main Author: | Fatras, Nicolas |
|---|---|
| Format: | info Lainnya |
| Terbitan: |
, 2018
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| Subjects: | |
| Online Access: |
https://zenodo.org/record/3715108 |
Daftar Isi:
- This study focuses on the fatigue behaviour of a semi-submersible floating offshore wind turbine. Using Lagrange’s equation of motion, a simplified model of the system is set up in the frequency domain, taking into account wind and ocean wave external forces. The frequency domain’s faster computation times allow to test the model for a wider range of environmental conditions and subsequently optimise a passive control system over a larger range of parameters. To operate in the frequency domain, linearisation methods are applied to some forces. If the ensuing results are not accurate enough, frequency transformations from time-domain outputs are taken from the literature to correctly represent highly non-linear forces. Based on the dynamic model results, an analysis of the fatigue loads at the tower base is obtained from the differential movement between the floating platform and the tower. The frequencies contributing the most to fatigue are identified, taking into account the probability distribution of the frequency content of the external forces based on local weather data. Finally, tuned mass dampers (TMD) are used for fatigue reduction in the identified critical frequency range. The TMDs’ efficiency is measured by the Damage Equivalent Load (DEL) reduction at the tower base. A parametric study is done to evaluate the optimal characteristics of the TMDs, including mass, position, damping coefficient, stiffness and total number of dampers.