Joint Description Methods of Wind and Waves for the Design of Offshore Wind Turbines

2009 ◽  
Vol 43 (3) ◽  
pp. 23-33 ◽  
Author(s):  
Kim E. Mittendorf
Keyword(s):  
Wind Energy ◽  
Wind Wave ◽  
Limit State ◽  
Wave Model ◽  
Design Guidelines ◽  
Offshore Wind ◽  
Ultimate Limit State ◽  
Wave Loads ◽  
Offshore Wind Energy ◽  
The North

AbstractWind and wave loads are equally important for the design of offshore wind energy structures. For the design against an ultimate limit state or fatigue, the engineer has to estimate the combination of loads that are likely to occur simultaneously during the design life of the wind turbine. This is quite a complex task, involving different wind/wave models, load-calculation methods and statistical analysis of simultaneous extreme wind and wave conditions. Moreover, reliable and realistic methods for the assessment of the service life of an offshore wind energy converter under combined wind and wave loads are necessary. However, the current design guidelines (Det Norske Veritas or German Lloyd) provide hardly any information on how to model the wind and wave correlation. In this article, several approaches for obtaining the required wind-wave correlation for the design have been investigated. Manual wave forecasting methods, spectral sea state descriptions and numerical wave model data have been compared to simultaneously measured wind and wave data from the FINO research platform in the German Bight of the North Sea. The used approaches are general and can be easily applied to different data sets from different regions.

Fatigue and Serviceability Limit State Model Basis for Assessment of Offshore Wind Energy Converters

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
S. Thöns ◽  
M. H. Faber ◽  
W. Rücker
Keyword(s):  
Wind Energy ◽  
Limit State ◽  
Sensitivity Study ◽  
Offshore Wind ◽  
Ultimate Limit State ◽  
Offshore Wind Energy ◽  
Limit States ◽  
Serviceability Limit State ◽  
State Models ◽  
Energy Converters

This paper develops the models for the structural performance of the loading and probabilistic characterization for the fatigue and the serviceability limit states for the support structure of offshore wind energy converters. These models and a sensitivity study are part of a risk based assessment and monitoring framework and will be applied for establishing the “as designed and constructed” reliability as prior information for the assessment and the design of monitoring systems. The constitutive physical equations are introduced in combination with the fatigue and serviceability limit state requirements as the starting point for the development of the structural performance and loading models. With these models introduced in detail, several modeling aspects for both limit states are analyzed. This includes analyses of the influence on the hot spot stresses by applying a contact formulation for the pile guide brace connection and the application of a finite element formulation using solid elements. Further, the comparison of the natural frequencies of a discrete rotor model with a continuous rotor model is documented. To account for uncertainties associated with the structural and loading models, a probabilistic model is derived on the basis of literature review and measurement data from a prototype Multibrid M5000 support structure. The sensitivity study is based on the calculation of a nonlinear coefficient of correlation in conjunction with predetermined designs of experiments. This is conducted by a systematic analysis of the influence of the random variables on limit state responses and hence on the structural reliability. Integrating the analyses and sensitivity studies of the fatigue and serviceability limit state models developed in this paper as well as the ultimate limit state models in Thöns et al. (“Ultimate Limit State Model Basis for Assessment of Offshore Wind Energy Converters,” ASME J. Offshore Mech. Arct. Eng.), the model basis for the assessment is completed. The process of establishing and analyzing such a model basis contributes to a detailed understanding of the deterministic and probabilistic characteristics of the structure and provides valuable insights in regard to the significance of available data.

Ultimate Limit State Model Basis for Assessment of Offshore Wind Energy Converters

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
S. Thöns ◽  
M. H. Faber ◽  
W. Rücker
Keyword(s):  
Finite Element ◽  
Wind Energy ◽  
Limit State ◽  
Offshore Wind ◽  
Sensitivity Analyses ◽  
Ultimate Limit State ◽  
Offshore Wind Energy ◽  
Support Structure ◽  
Ultimate Limit ◽  
Energy Converters

This paper establishes the model basis regarding the ultimate limit state consisting of structural, loading, and probabilistic models of the support structure of offshore wind energy converters together with a sensitivity study. The model basis is part of a risk based assessment and monitoring framework and will be applied for establishing the “as designed and constructed” reliability as prior information for the assessment and as a basis for designing a monitoring system. The model basis is derived considering the constitutive physical equations and the methodology of solving these which then in combination with the ultimate limit state requirements leads to the specific constitutive relations. As a result finite element models based on shell elements incorporating a structural and a loading model are introduced and described in detail. Applying these models the ultimate capacity of the support structure and the tripod structure are determined with a geometrically and materially nonlinear finite element analysis. The observed failure mechanisms are the basis for the definition of the ultimate limit state responses. A probabilistic model accounting for the uncertainties involved is derived on the basis of literature review and measurement data from a prototype Multibrid M5000 support structure. In combination with the developed structural and loading models, sensitivity analyses in regard to the responses are performed to enhance the understanding and to refine the developed models. To this end, as the developed models necessitate substantial numerical efforts for the probabilistic response analysis predetermined designs of numerical experiments are applied for the calculation of the sensitivities using the Spearman rank correlation coefficient. With this quantification of the sensitivity of the random variables on the responses including nonlinearity the refinement of the model is performed on a quantitative basis.

scholarly journals Offshore Wind Energy Resource Atlas of Asturias (N Spain)

Proceedings ◽  
2018 ◽  
Vol 2 (23) ◽  
pp. 1416
Author(s):  
Mario López ◽  
Noel Rodríguez-Fuertes ◽  
Rodrigo Carballo
Keyword(s):  
Wind Speed ◽  
Numerical Model ◽  
Wind Energy ◽  
Energy Resource ◽  
Offshore Wind ◽  
Power Curve ◽  
Offshore Wind Energy ◽  
The North ◽  
North Of Spain ◽  
First Time

This work assesses for the first time the offshore wind energy resource in Asturias, a region in the North of Spain. Numerical model and observational databases are used to characterize the gross wind energy resource at different points throughout the area of study. The production of several wind turbines is then forecasted on the basis of each technology power curve and the wind speed distributions. The results are mapped for a better interpretation and discussion.

Comparison of Design Guidelines for Offshore Wind Energy Systems

2007 ◽  
Author(s):  
Rakesh Saigal ◽  
Dan Dolan ◽  
Armen Kiureghian ◽  
Tim Camp ◽  
Charles Smith
Keyword(s):  
Wind Energy ◽  
Energy Systems ◽  
Design Guidelines ◽  
Offshore Wind ◽  
Offshore Wind Energy ◽  
Wind Energy Systems

scholarly journals Review of wind-wave coupling models for large-eddy simulation of the marine atmospheric boundary layer

2021 ◽  
Author(s):  
Georgios Deskos ◽  
Joseph C. Y. Lee ◽  
Caroline Draxl ◽  
Michael A. Sprague
Keyword(s):  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Wind Energy ◽  
Atmospheric Boundary Layer ◽  
Wind Wave ◽  
Offshore Wind ◽  
Marine Atmospheric Boundary Layer ◽  
Offshore Wind Energy ◽  
Eddy Simulation ◽  
Large Eddy

AbstractWe present a review of existing wind-wave coupling models and parameterizations used for large-eddy simulation of the marine atmospheric boundary layer. The models are classified into two main categories: (i) the wave phaseaveraged, sea-surface-roughness models and (ii) the wave phase-resolved models. Both categories are discussed from their implementation, validity, and computational efficiency viewpoints with emphasis given on their applicability in offshore wind energy problems. In addition to the various models discussed, a review of laboratory-scale and field-measurement databases are presented thereafter. The majority of the presented data have been gathered over many decades of studying air-sea interaction phenomena, with the most recent ones compiled to reflect an offshore wind energy perspective. Both provide valuable data for model validation. Finally, we also discuss the modeling knowledge gaps and computational challenges ahead.

scholarly journals Exploitation of the far-offshore wind energy resource by fleets of energy ships – Part 1: Energy ship design and performance

2020 ◽  
Vol 5 (3) ◽  
pp. 839-853 ◽  
Author(s):  
Aurélien Babarit ◽  
Gaël Clodic ◽  
Simon Delvoye ◽  
Jean-Christophe Gilloteaux
Keyword(s):  
Wind Energy ◽  
North Atlantic Ocean ◽  
Energy Resource ◽  
Energy Conversion Efficiency ◽  
Energy Performance ◽  
Ship Design ◽  
Chemical Energy ◽  
Offshore Wind ◽  
Offshore Wind Energy ◽  
The North

Abstract. This paper deals with a new concept for the conversion of far-offshore wind energy into sustainable fuel. It relies on autonomously sailing energy ships and manned support tankers. Energy ships are wind-propelled. They generate electricity using water turbines attached underneath their hull. Since energy ships are not grid-connected, they include onboard power-to-X plants for storage of the produced energy. In the present work, the energy vector is methanol. The aim of the paper is to propose an energy ship design and to provide an estimate for its energy performance as function of the wind conditions. The energy performance assessment is based on a numerical model which is described in the paper. Results show that the wind energy-to-methanol (chemical energy) conversion efficiency is 24 % and that such an energy ship deployed in the North Atlantic Ocean could produce approximately 5 GWh per annum of chemical energy (900 t of methanol per annum).

Wind/Wave Misalignment Effects on Mooring Line Tensions for a Spar Buoy Wind Turbine

2018 ◽  
Author(s):  
Luigia Riefolo ◽  
Fernando del Jesus ◽  
Raúl Guanche García ◽  
Giuseppe Roberto Tomasicchio ◽  
Daniela Pantusa
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Wave ◽  
Offshore Wind ◽  
Mooring Line ◽  
Ultimate Limit State ◽  
International Electrotechnical Commission ◽  
Wave Loads ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

The design methodology for mooring systems for a spar buoy wind turbine considers the influence of extreme events and wind/wave misalignments occurring in its lifetime. Therefore, the variety of wind and wave directions affects over the seakeeping and as a result the evaluation of the maxima loads acting on the spar-buoy wind turbine. In the present paper, the importance of wind/wave misalignments on the dynamic response of spar-type floating wind turbine [1] is investigated. Based on standards, International Electrotechnical Commission IEC and Det Norske Veritas DNV the design of position moorings should be carried out under extreme wind/wave loads, taking into account their misalignments with respect to the structure. In particular, DNV standard, in ‘Position mooring’ recommendations, specifies in the load cases definition, if site specific data is not available, to consider non-collinear environment to have wave towards the unit’s bow (0°) and wind 30° relative to the waves. In IEC standards, the misalignment of the wind and wave directions shall be considered to design offshore wind turbines and calculate the loads acting on the support structure. Ultimate Limit State (ULS) analyses of the OC3-Hywind spar buoy wind turbine are conducted through FAST code, a certified nonlinear aero-hydro-servo-elastic simulation tool by the National Renewable Energy Laboratory’s (NREL’s). This software was developed for use in the International Energy Agency (IEA) Offshore Code Comparison Collaborative (OC3) project, and supports NREL’s offshore 5-MW baseline turbine. In order to assess the effects of misaligned wind and wave, different wind directions are chosen, maintaining the wave loads perpendicular to the structure. Stochastic, full-fields, turbulence simulator Turbsim is used to simulate the 1-h turbulent wind field. The scope of the work is to investigate the effects of wind/wave misalignments on the station-keeping system of spar buoy wind turbine. Results are presented in terms of global maxima determined through mean up-crossing with moving average, which, then, are modelled by a Weibull distribution. Finally, extreme values are estimated depending on global maxima and fitted on Gumbel distribution. The Most Probable Maximum value of mooring line tensions is found to be influenced by the wind/wave misalignments. The present paper is organized as follows. Section ‘Introduction’, based on a literature study, gives useful information on the previous studies conducted on the wind/wave misalignments effects of floating offshore wind turbines. Section ‘Methodology’ describes the applied methodology and presents the spar buoy wind turbine, the used numerical model and the selected environmental conditions. Results and the corresponding discussion are given in Section ‘Results and discussion’ for each load case corresponding to the codirectional and misaligned wind and wave loads. Results are presented and discussed in time and frequency domains. Finally, in Section ‘Conclusion’ some conclusions are drawn.

scholarly journals Exploitation of the far-offshore wind energy resource by fleets of energy ships. Part A. Energy ship design and performance

2020 ◽  
Author(s):  
Aurélien Babarit ◽  
Gaël Clodic ◽  
Simon Delvoye ◽  
Jean-Christophe Gilloteaux
Keyword(s):  
Wind Energy ◽  
North Atlantic Ocean ◽  
Energy Resource ◽  
Energy Conversion Efficiency ◽  
Energy Performance ◽  
Ship Design ◽  
Chemical Energy ◽  
Offshore Wind ◽  
Offshore Wind Energy ◽  
The North

Abstract. This paper deals with a new concept for the conversion of far-offshore wind energy into sustainable fuel. It relies on autonomously sailing energy ships and manned support tankers. Energy ships are wind-propelled. They generate electricity using water turbines attached underneath their hull. Since energy ships are not grid-connected, they include onboard power-to-X plants for storage of the produced energy. In the present work, the energy vector is methanol. The aim of the paper is to propose an energy ship design and to provide an estimate for its energy performance as function of the wind conditions. The energy performance assessment is based on a numerical model which is described in the paper. Results show that the wind energy-to-methanol (chemical energy) conversion efficiency is 24 % and that such energy ship deployed in the North Atlantic Ocean could produce approximately 5 GWh per annum of chemical energy (900 tonnes of methanol per annum).

Sign in / Sign up

Export Citation Format

Share Document