Wind Wave Misalignment In The Loads Analysis Of A Floating Offshore Wind Turbine Preprint
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Wind Wave Misalignment In The Loads Analysis Of A Floating Offshore Wind Turbine Preprint
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Author :
language : en
Publisher:
Release Date : 2014
Wind Wave Misalignment In The Loads Analysis Of A Floating Offshore Wind Turbine Preprint written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
Wind resources far from the shore and in deeper seas have encouraged the offshore wind industry to look into floating platforms. The International Electrotechnical Commission (IEC) is developing a new technical specification for the design of floating offshore wind turbines that extends existing design standards for land-based and fixed-bottom offshore wind turbines. The work summarized in this paper supports the development of best practices and simulation requirements in the loads analysis of floating offshore wind turbines by examining the impact of wind/wave misalignment on the system loads under normal operation. Simulations of the OC3-Hywind floating offshore wind turbine system under a wide range of wind speeds, significant wave heights, peak-spectral periods and wind/wave misalignments have been carried out with the aero-servo-hydro-elastic tool FAST [4]. The extreme and fatigue loads have been calculated for all the simulations. The extreme and fatigue loading as a function of wind/wave misalignment have been represented as load roses and a directional binning sensitivity study has been carried out. This study focused on identifying the number and type of wind/wave misalignment simulations needed to accurately capture the extreme and fatigue loads of the system in all possible metocean conditions considered, and for a down-selected set identified as the generic US East Coast site. For this axisymmetric platform, perpendicular wind and waves play an important role in the support structure and including these cases in the design loads analysis canimprove the estimation of extreme and fatigue loads. However, most structural locations see their highest extreme and fatigue loads with aligned wind and waves. These results are specific to the spar type platform, but it is expected that the results presented here will be similar to other floating platforms.
Wind Wave Misalignment In The Loads Analysis Of A Floating Offshore Wind Turbine
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Author : L. Barj
language : en
Publisher:
Release Date : 2014
Wind Wave Misalignment In The Loads Analysis Of A Floating Offshore Wind Turbine written by L. Barj and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Ocean energy resources categories.
Design Load Analysis Of Two Floating Offshore Wind Turbine Concepts
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Author : Gordon M. Stewart
language : en
Publisher:
Release Date : 2016
Design Load Analysis Of Two Floating Offshore Wind Turbine Concepts written by Gordon M. Stewart and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Much of the United States' wind resource is located over deep water where fixed-bottom offshore wind turbines are cost-prohibitive. To capture this energy, floating offshore wind turbines are being developed. However, current design standards do not explicitly cover issues relating to floating offshore wind turbines, which leads to risk and uncertainty in the design process. Two important issues that this dissertation investigates are the effect of simulation length and wind and wave misalignment on fatigue and ultimate loads. Experience in the offshore floating oil and gas industry has recommended simulation lengths of 3-6 hours, but the wind industry typically simulates between 10 minutes and one hour. The reasons for these simulation lengths is explored and recommendations for floating offshore wind turbines are made. The current offshore wind turbine design standard states that co-aligned wind and waves are a conservative ``worst-case'' scenario for loads, but this assertion may only hold true for fixed-bottom offshore turbines. A large operational design-space set of simulations are run to determine the impact of wind and wave misalignment on floating offshore turbines. Using results from both the simulation length and wind/wave misalignment study, probabilistic methods are used to determine a minimum set of simulations that is able to accurately characterize the loads response of floating platforms. Reduction of avian impacts have long been an important concern for the installation of wind farms. There is large uncertainty in the impacts of offshore wind farms on seabirds in the United States, as no offshore wind farms are currently operating. In this dissertation, experience from Europe is used to create a model of seabirds' interaction with fixed-bottom offshore wind farms. This model is used in a multi-objective optimization of the layout of a generic fixed-bottom offshore wind farm, considering both impacts on birds as well as power production. To simulate a farm comprised of floating offshore wind turbines, uncertainty in the positions of the turbines in the farm is introduced, and the layout is once again subjected to a multi-objective optimization.
Computation Of Wave Loads Under Multidirectional Sea States For Floating Offshore Wind Turbines Preprint
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Author :
language : en
Publisher:
Release Date : 2014
Computation Of Wave Loads Under Multidirectional Sea States For Floating Offshore Wind Turbines Preprint written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
This paper focuses on the analysis of a floating wind turbine under multidirectional wave loading. Special attention is given to the different methods used to synthesize the multidirectional sea state. This analysis includes the double-sum and single-sum methods, as well as an equal-energy discretization of the directional spectrum. These three methods are compared in detail, including theergodicity of the solution obtained. From the analysis, the equal-energy method proved to be the most computationally efficient while still retaining the ergodicity of the solution. This method was chosen to be implemented in the numerical code FAST. Preliminary results on the influence of these wave loads on a floating wind turbine showed significant additional roll and sway motion of theplatform.
Comparison Of Methods For The Computation Of Wave Forcing
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Author : Olga Glöckner
language : en
Publisher: GRIN Verlag
Release Date : 2018-05-18
Comparison Of Methods For The Computation Of Wave Forcing written by Olga Glöckner and has been published by GRIN Verlag this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-05-18 with Technology & Engineering categories.
Presentation slides from the year 2014 in the subject Engineering - Civil Engineering, grade: 1,0, University of Hannover, language: English, abstract: Unlike fossil fuels (e.g. oil, coal and natural gas), wind energy is a renewable energy resource. Since winds at sea are stronger and more consistent than onshore winds, the demand for offshore wind turbines has increased over the last years. As energy can be produced more efficient in deeper water, several floating offshore wind turbine constructions, such as the OC3 Hywind spar-buoy, have been proposed. The design of floating wind turbines depends on the simulation of the system behavior caused by exciting forces. This thesis deals with the comparison between different methods for calculating wave forces and resulting platform motions of a floating offshore wind turbine. On the one hand, wave exciting loads computed with Morison’s equation are compared to the hydrodynamic forces simulated by the open source code FAST on the basis of the diffraction theory. On the other hand, response motions of the floating structure are simulated by the commercial offshore software SESAM in the frequency domain and compared with the motions calculated by FAST in the time domain.
Simulation Length Requirements In The Loads Analysis Of Offshore Floating Wind Turbines
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Author :
language : en
Publisher:
Release Date : 2013
Simulation Length Requirements In The Loads Analysis Of Offshore Floating Wind Turbines written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
The goal of this paper is to examine the appropriate length of a floating offshore wind turbine (FOWT) simulation - a fundamental question that needs to be answered to develop design requirements. To examine this issue, a loads analysis of an example FOWT was performed in FAST with varying simulation lengths. The offshore wind system used was the OC3-Hywind spar buoy, which was developed for use in the International Energy Agency Code Comparison Collaborative Project and supports NREL's offshore 5-megawatt baseline turbine. Realistic metocean data from the National Oceanic and Atmospheric Administration and repeated periodic wind files were used to excite the structure. The results of the analysis clearly show that loads do not increase for longer simulations. In regards to fatigue, a sensitivity analysis shows that the procedure used for counting half cycles is more important than the simulation length itself. Based on these results, neither the simulation length nor the periodic wind files affect response statistics and loads for FOWTs (at least for the spar studied here); a result in contrast to the offshore oil and gas industry, where running simulations of at least 3 hours in length is common practice.
Simulation Length Requirements In The Loads Analysis Of Offshore Floating Wind Turbines
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Author : Lorenz Haid
language : en
Publisher:
Release Date : 2013
Simulation Length Requirements In The Loads Analysis Of Offshore Floating Wind Turbines written by Lorenz Haid and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
Loads Analysis Of A Floating Offshore Wind Turbine Using Fully Coupled Simulation
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Author :
language : en
Publisher:
Release Date : 2007
Loads Analysis Of A Floating Offshore Wind Turbine Using Fully Coupled Simulation written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with Deep-sea mooring categories.
The vast deepwater wind resource represents a potential to use floating offshore wind turbines to power much of the world with renewable energy. Comprehensive simulation tools that account for the coupled excitation and response of the complete system, including the influences of wind-inflow, aerodynamics, structural dynamics, controls, and, for offshore systems, waves, currents, and hydrodynamics, are used to design and analyze wind turbines. The application of such tools in the analysis of floating offshore wind turbines has previously been investigated to only a limited extent. There are numerous possible concepts for floating offshore wind turbine platforms, including a variety of configurations currently used in the offshore oil and gas industries. Coupled analyses are needed to determine their technical and economic feasibility. This paper presents the use of fully coupled aero-hydro-servo-elastic simulation tools to perform a preliminary loads analysis of a 5-MW offshore wind turbine supported by a barge with catenary moorings, which is one of the many promising floating platform concepts.
A Comparison Of Methods For Computation Of Wave Forcing
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Author : Olga Glöckner
language : en
Publisher: GRIN Verlag
Release Date : 2018-05-17
A Comparison Of Methods For Computation Of Wave Forcing written by Olga Glöckner and has been published by GRIN Verlag this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-05-17 with Technology & Engineering categories.
Diploma Thesis from the year 2014 in the subject Engineering - Civil Engineering, grade: 1,0, University of Hannover (A&M University Texas, Ludwig-Franzius-Institut für Wasserbau, Ästuar- und Küsteningenieurwesen), language: English, abstract: Unlike fossil fuels (for example oil, coal and natural gas), wind energy is a renewable energy resource. Since winds at sea are stronger and more consistent than onshore winds, the demand for offshore wind turbines has increased over the last years. As energy can be produced more efficient in deeper water, several floating offshore wind turbine constructions, such as the OC3 Hywind spar-buoy, have been proposed. The design of floating wind turbines depends on the simulation of the system behavior caused by exciting forces. This thesis deals with the comparison between different methods for calculating wave forces and resulting platform motions of a floating offshore wind turbine. On the one hand, wave exciting loads computed with Morison’s equation are compared to the hydrodynamic forces simulated by the open source code FAST on the basis of the diffraction theory. On the other hand, response motions of the floating structure are simulated by the commercial offshore software SESAM in the frequency domain and compared with the motions calculated by FAST in the time domain.
Comparison Of Second Order Loads On A Tension Leg Platform For Wind Turbines Preprint
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Author :
language : en
Publisher:
Release Date : 2015
Comparison Of Second Order Loads On A Tension Leg Platform For Wind Turbines Preprint written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
The first objective of this work is to compare the two floating offshore wind turbine simulation packages {DIFFRAC+aNySIM} and {WAMIT+FAST}. The focus is on second-order wave loads, and so first- and second-order wave loads are applied to a structure sequentially for a detailed comparison and a more precise analysis of the effects of the second-order loads. aNySIM does not have the capability to model flexible bodies, and so the simulations performed in this tool are done assuming a rigid body. FAST also assumes that the platform is rigid, but can account for the flexibility of the tower. The second objective is to study the effects of the second-order loads on the response of a TLP floating wind turbine. The flexibility of the tower must be considered for this investigation, and therefore only FAST is used.