Energies 2013, 6(8), 4097-4116; doi:10.3390/en6084097
Article

Damping Wind and Wave Loads on a Floating Wind Turbine

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Received: 22 April 2013; in revised form: 11 July 2013 / Accepted: 23 July 2013 / Published: 9 August 2013
(This article belongs to the Special Issue Wind Turbines 2013)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: Offshore wind energy capitalizes on the higher and less turbulent wind speeds at sea. To enable deployment of wind turbines in deep-water locations, structures are being explored, where wind turbines are placed on a floating platform. This combined structure presents a new control problem, due to the partly unconstrained movement of the platform and ocean wave excitation. If this additional complexity is not dealt with properly, this may lead to a significant increase in the structural loads and, potentially, instability of the controlled system. In this paper, the wave excitation is investigated, and we show the influence that both wind speed, wave frequencies and misalignment between wind and waves have on the system dynamics. A new control model is derived that extends standard turbine models to include the hydrodynamics, additional platform degrees of freedom, the platform mooring system and tower side-side motion, including gyroscopic effects. The models support a model-based design that includes estimators for wind speed and wave frequency. The design is applied to a number of examples representing different wind and wave conditions and successfully demonstrates a reduction in the structural oscillations, while improving power performance.
Keywords: optimal control; closed loop systems; wind energy
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MDPI and ACS Style

Christiansen, S.; Bak, T.; Knudsen, T. Damping Wind and Wave Loads on a Floating Wind Turbine. Energies 2013, 6, 4097-4116.

AMA Style

Christiansen S, Bak T, Knudsen T. Damping Wind and Wave Loads on a Floating Wind Turbine. Energies. 2013; 6(8):4097-4116.

Chicago/Turabian Style

Christiansen, Søren; Bak, Thomas; Knudsen, Torben. 2013. "Damping Wind and Wave Loads on a Floating Wind Turbine." Energies 6, no. 8: 4097-4116.

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