OC6 Phase I: Investigating the underprediction of low-frequency hydrodynamic loads and responses of a floating wind turbine

Abstract Research in floating wind turbine resulted in the publication of a number of studies comparing wind turbine loads on a variety of floaters and fixed foundations. Some of them concluded that the blade and drivetrain loads would only be marginally increased -if increased at all — when a turbine would be installed on a floater [1] [2] and [3]. This paper proposes to evaluate how rotor and tower loads are correlated to nacelle acceleration, wind and wave conditions. It can somehow be considered as an extension to a barge-type floater and onsite measurements, of published work applied to fixed offshore wind turbines [4] and a spar-type floating wind turbine [5]. The body of data used for this exercise includes results from full-scale prototype measurements and simulations for a variety of turbine ratings. It can be concluded that in power production cases, blade and main shaft loads are only weakly correlated to nacelle low frequency accelerations and hence wave conditions, hence aerodynamic loads are still the main driver for rotor and tower top loads. In rotor-idling conditions, the situation is mainly dependent on the wind speed range, but aerodynamics are the largest contributor of blade and main shaft loads in severe wind conditions. These results can help understand where design uncertainties lie in floating wind turbine loads.

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Experimental Investigation of the Coupling Between Aero- and Hydrodynamical Loads On A 12 MW Semi-Submersible Floating Wind Turbine

10.1115/omae2021-62980 ◽

2021 ◽

Author(s):

Maxime Thys ◽

Carlos Souza ◽

Thomas Sauder ◽

Nuno Fonseca ◽

Petter Andreas Berthelsen ◽

...

Keyword(s):

Wind Turbine ◽

Low Frequency ◽

Turbine Rotor ◽

Ocean Basin ◽

Sea State ◽

Turbulent Wind ◽

Aerodynamic Loads ◽

Wave Elevation ◽

Floating Wind Turbine ◽

Quantities Of Interest

Abstract Model tests were performed with a model of the INO WINDMOOR 12 MW floating wind turbine in the Ocean Basin at SINTEF Ocean. The tests were done at a scale of 1:40. RealTime Hybrid Model testing was used for the modelling of the wind turbine rotor and aerodynamic loads. A subset of the results is analysed to study the influence of the wind on the platform motions, the acceleration at tower top, the loads at base of tower and the relative wave elevation. The study is based on the comparison of the quantities of interest for different tests with the same moderate sea-state but with different wind modelling: no wind, constant thrust force, turbulent wind of 11.5 m/s and turbulent wind of 25 m/s. The wind modelling has a minimal influence on the platform surge and pitch response in the wave-frequency range. On the other hand, the aerodynamic loads, including wind turbine controller dynamics and turbulent wind, has an important impact on the low-frequency surge and pitch response. The aerodynamic loads are important for the loads at tower base due to the dominance of the tower-RNA induced gravitational loads at low-frequency. Maximum relative wave elevation was found to be mainly dependent on the thrust induced mean pitch angle.

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Uncertainty modeling in reliability analysis of floating wind turbine support structures

Renewable Energy ◽

10.1016/j.renene.2020.10.068 ◽

2021 ◽

Vol 165 ◽

pp. 88-108

Author(s):

Salem Okpokparoro ◽

Srinivas Sriramula

Keyword(s):

Wind Turbine ◽

Reliability Analysis ◽

Uncertainty Modeling ◽

Support Structures ◽

Floating Wind Turbine

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Fluid-structure interaction and stress analysis of a floating wind turbine

Marine Structures ◽

10.1016/j.marstruc.2021.102970 ◽

2021 ◽

Vol 78 ◽

pp. 102970

Author(s):

B. Wiegard ◽

M. König ◽

J. Lund ◽

L. Radtke ◽

S. Netzband ◽

...

Keyword(s):

Wind Turbine ◽

Stress Analysis ◽

Fluid Structure Interaction ◽

Fluid Structure ◽

Structure Interaction ◽

Floating Wind Turbine

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A novel conceptual design of a dynamically positioned floating wind turbine

Ocean Engineering ◽

10.1016/j.oceaneng.2020.108528 ◽

2021 ◽

Vol 221 ◽

pp. 108528

Author(s):

Shengwen Xu ◽

Motohiko Murai ◽

Xuefeng Wang ◽

Kensaku Takahashi

Keyword(s):

Wind Turbine ◽

Conceptual Design ◽

Floating Wind Turbine

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Fault detection and diagnosis of a blade pitch system in a floating wind turbine based on Kalman filters and artificial neural networks

Renewable Energy ◽

10.1016/j.renene.2020.12.116 ◽

2021 ◽

Author(s):

Seongpil Cho ◽

Minjoo Choi ◽

Zhen Gao ◽

Torgeir Moan

Keyword(s):

Neural Networks ◽

Artificial Neural Networks ◽

Fault Detection ◽

Wind Turbine ◽

Kalman Filters ◽

Fault Detection And Diagnosis ◽

Floating Wind Turbine ◽

Artificial Neural ◽

Pitch System ◽

Detection And Diagnosis

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Dynamic Modeling of an Offshore Floating Wind Turbine for Application in the Mediterranean Sea

Energies ◽

10.3390/en14010248 ◽

2021 ◽

Vol 14 (1) ◽

pp. 248

Author(s):

Lorenzo Cottura ◽

Riccardo Caradonna ◽

Alberto Ghigo ◽

Riccardo Novo ◽

Giovanni Bracco ◽

...

Keyword(s):

Wind Turbine ◽

Mediterranean Sea ◽

Wind Farm ◽

Reference Model ◽

Wide Spectrum ◽

Wind Farms ◽

Offshore Wind ◽

Floating Wind Turbine ◽

The Mediterranean ◽

Offshore Floating Wind Turbine

Wind power is emerging as one of the most sustainable and low-cost options for energy production. Far-offshore floating wind turbines are attractive in view of exploiting high wind availability sites while minimizing environmental and landscape impact. In the last few years, some offshore floating wind farms were deployed in Northern Europe for technology validation, with very promising results. At present time, however, no offshore wind farm installations have been developed in the Mediterranean Sea. The aim of this work is to comprehensively model an offshore floating wind turbine and examine the behavior resulting from a wide spectrum of sea and wind states typical of the Mediterranean Sea. The flexible and accessible in-house model developed for this purpose is compared with the reference model FAST v8.16 for verifying its reliability. Then, a simulation campaign is carried out to estimate the wind turbine LCOE (Levelized Cost of Energy). Based on this, the best substructure is chosen and the convenience of the investment is evaluated.

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