Journal cover Journal topic
Wind Energy Science The interactive open-access journal of the European Academy of Wind Energy
https://doi.org/10.5194/wes-2018-25
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research articles
09 Apr 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Wind Energy Science (WES).
An efficient frequency-domain model for quick load analysis of floating offshore wind turbines
Antonio Pegalajar-Jurado, Michael Borg, and Henrik Bredmose Department of Wind Energy, Technical University of Denmark, Nils Koppels Allé 403, 2800 Kongens Lyngby, Denmark
Abstract. A model for Quick Load Analysis of Floating wind turbines, QuLAF, is presented and validated here. The model is a linear, frequency-domain, efficient tool with four planar degrees of freedom: platform surge, heave, pitch and tower modal deflection. The model relies on state-of-the-art tools from which hydrodynamic, aerodynamic and mooring loads are extracted and cascaded into QuLAF. Hydrodynamic and aerodynamic loads are precomputed in WAMIT and FAST respectively, while the mooring system is linearized around the equilibrium position for each wind speed using MoorDyn. An approximate approach to viscous hydrodynamic damping is developed, and the aerodynamic damping is extracted from decay tests specific for each degree of freedom. Without any calibration, the model predicts the motions of the system in stochastic wind and waves with good accuracy when compared to FAST. The damage-equivalent bending moment at the tower bottom is estimated with errors between 0.2 % and 11.3 % for all the load cases considered. The largest errors are associated with the most severe wave climates for wave-only conditions and with turbine operation around rated wind speed for combined wind and waves. The computational speed of the model is between 1300 and 2700 times faster than real-time.
Citation: Pegalajar-Jurado, A., Borg, M., and Bredmose, H.: An efficient frequency-domain model for quick load analysis of floating offshore wind turbines, Wind Energ. Sci. Discuss., https://doi.org/10.5194/wes-2018-25, in review, 2018.
Antonio Pegalajar-Jurado et al.
Antonio Pegalajar-Jurado et al.
Antonio Pegalajar-Jurado et al.

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Short summary
This paper presents a simplified numerical model to quickly predict motion and loads of floating offshore wind turbines. Hydrodynamic, aerodynamic and mooring loads are extracted from higher-fidelity numerical tools. Without calibration, the model can predict with good accuracy the motions of the system in real wind and wave conditions. Loads at the tower base are estimated with errors between 0.2 % and 11.3 %. The model can simulate between 1300 and 2700 times faster than real-time.
This paper presents a simplified numerical model to quickly predict motion and loads of floating...
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