Room:
Egbert-von-Hoyer Hall
Topic:
H. Offshore wind energy
Form of presentation:
Oral
Duration:
100 Minutes
Chaired by: M. Muskulus, P. Schaumann
16:30
Design study and full scale MBS-CFD simulation of the IDEOL floating offshore wind turbine foundation
Friedemann Borisade | University of Stuttgart | Germany
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Authors:
Friedemann Borisade | University of Stuttgart | Germany
Thomas Choisnet | Germany
Po Wen Cheng | Germany
A two MW floating offshore wind turbine is developed within the EU-FP7 project FLOATGEN. The focus of this paper is to perform design studies of the mooring foundation at the hull and to investigate the full scale floater concept in a coupled MBS-CFD environment at regular waves. Measurements from wave tank model tests are used for validation. The results show the potential of CFD methods to be used as virtual test bed during the design process.
16:50
Wind tunnel validation of AeroDyn, within LIFES50+ project: imposed Surge and Pitch tests
Dr. Ilmas Bayati | POLITECNICO DI MILANO | Italy
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Authors:
Dr. Ilmas Bayati | POLITECNICO DI MILANO | Italy
Ilmas Bayati | Italy
Marco Belloli | Italy
Luca Bernini | Italy
Alberto Zasso | Italy
This paper presents the rst set of results of the steady and unsteady wind tunnel tests, performed at Politecnico di Milano wind tunnel, on a 1/75 rigid scale model of the DTU 10 MW wind turbine, within the LIFES50+ project. The aim of these tests is the validation of the open source code AeroDyn developed at NREL. Numerical and experimental steady results are compared in terms of thrust and torque coe cients, showing good agreement, as well as for unsteady measurements gathered with a 2 degree-of-freedom test rig, capable of imposing the displacements at the base of the model, and providing the surge and pitch motion of the oating o shore wind turbine scale model. The measurements of the unsteady test con guration are compared with AeroDyn/Dynin module results, implementing the generalized dynamic wake (GDW) model. Numerical and experimental comparison showed similar behaviours in terms of non linear hysteresis, however some discrepancies are herein reported and need further data analysis and interpretations about the aerodynamic integral quantities, with a special attention to the physics of the unsteady phenomenon.
17:10
Control design methods for floating wind turbines for optimal disturbance rejection
Frank Lemmer | University of Stuttgart | Germany
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Author:
Frank Lemmer | University of Stuttgart | Germany
An analysis of the floating wind turbine as a multi-input-multi-output system investigating the effect of the control inputs on the system outputs is shown. These effects are compared to the ones of the disturbances from wind and waves in order to give insights for the selection of the control layout. The frequencies with the largest impact on the outputs due to limited effect of the controlled variables are identified. Finally, an optimal controller is designed as a benchmark and compared to a conventional PI-controller using only the rotor speed as input. Here, the previously found system properties, especially the difficulties to damp responses to wave excitation, are confirmed and verified through a spectral analysis with realistic environmental conditions. This comparison also assesses the quality of the employed simplified linear simulation model compared to the nonlinear model and shows that such an efficient frequency-domain evaluation for control design is feasible.
17:30
Experimental and numerical study of a 10MW TLP wind turbine in waves and wind
Antonio Pegalajar-Jurado | DTU | Denmark
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Authors:
Antonio Pegalajar-Jurado | DTU | Denmark
Anders Mandrup Hansen | Denmark
Robert Laugesen | Denmark
Robert Flemming Mikkelsen | Denmark
Michael Borg | Denmark
Taeseong Kim | Denmark
Nicolai Francis Heilskov | Denmark
Henrik Bredmose | Denmark
This paper presents tests on a 1:60 version of the DTU 10MW wind turbine mounted on a tension leg platform (TLP) and their numerical reproduction. Both the experimental setup and the numerical model are Froude-scaled, and the dynamic response of the floating wind turbine to wind and waves is compared to tests in terms of motion in the six degrees of freedom, nacelle acceleration and mooring line tension. The numerical model is implemented in the aero-elastic code Flex5, featuring the unsteady BEM method and the Morison equation for the modelling of aerodynamics and hydrodynamics, respectively. It was calibrated with the tests by matching key system features, namely the steady thrust curve and the decay tests in water. The calibrated model is used to reproduce the wind-wave climates in the laboratory, including regular and irregular waves, with and without wind. The model predictions are then compared to the measured data, and quantitative and qualitative agreements are found, as well as some discrepancies. Finally, the source of the discrepancies is discussed and some improvements in the numerical model are suggested in order to obtain a better agreement with the experiments.
17:50
Load extrapolations based on measurements from an offshore wind turbine at alpha ventus
Prof. Po Wen Cheng | University of Stuttgart | Germany
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Authors:
Prof. Po Wen Cheng | University of Stuttgart | Germany
Po Wen Cheng | Germany
Statistical extrapolations of loads can be used to estimate the extreme loads that are supposed to occur on average once in a given return period. Extrapolations of extreme loads recorded for a period of three years at different positions of an offshore wind turbine at the alpha ventus offshore test field have been performed. The difficulties that arise when using measured instead of simulated extreme loads in order to determine 50-year return loads will be discussed. The main challenge is outliers in the data that have a significant influence on the extrapolated extreme loads. Results of the short- and long-term extreme load extrapolations, comprising various methods for the extreme load extraction, the choice of the statistical distribution function as well as the fitting method are presented. Generally, load extrapolation with measurement data is possible, but the selection of the database and the choice of the distribution function and fitting method should be made carefully.