scholarly journals Response Characteristics of the DeepCwind Floating Wind Turbine Moored by a Single-Point Mooring System

2018 ◽  
Vol 8 (11) ◽  
pp. 2306 ◽  
Author(s):  
Yingyi Liu ◽  
Shigeo Yoshida ◽  
Hiroshi Yamamoto ◽  
Akinori Toyofuku ◽  
Guanghua He ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Numerical Study ◽  
Single Point ◽  
Offshore Wind ◽  
Response Characteristics ◽  
Floating Wind Turbine ◽  
Decay Test ◽  
Response Amplitude Operators ◽  
Marine Engineering ◽  
Offshore Oil

In recent years, the SPM (Single-Point Mooring) concept has been widely employed in several branches of the naval architecture and marine engineering field, such as FPSOs (Floating Production, Storage and Offloading units), offshore oil rigs, etc., but not yet popular in the offshore wind energy. To investigate the response characteristics of an SPM-moored FWT (Floating Wind Turbine), in the present work, we perform a numerical study on the DeepCwind semisubmersible wind turbine, using the state-of-the-art open-source tool FAST. The free-decay test results show that the SPM layout affects the natural periods of the wind turbine in rotational modes, as well as the mooring stiffness of the diagonal rotational and crossing rotational-translational terms, especially in relation to the yaw mode. Comparisons of the RAOs (Response Amplitude Operators) elucidate that the presence of wind influences significantly the sway, roll and yaw motions of the SPM layout. Finally, the weathervane test shows that an asymmetry exists in the free-yaw motion response when the semisubmersible wind turbine is moored by an SPM system.

Study of a Floating Foundation for Wind Turbines

2012 ◽  
Author(s):  
Sébastien Gueydon ◽  
Sam Weller
Keyword(s):  
Wind Turbine ◽  
Shallow Water ◽  
Numerical Study ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Farms ◽  
Physical Measurements ◽  
Floating Wind Turbine ◽  
Wave Basin ◽  
Floating System

Offshore wind farms are currently located predominantly in shallow water as it is possible to cost effectively install bottom fixed offshore turbines. Where shallow water sites are not available, floating offshore turbines could be a better solution than bottom fixed turbines. Currently three main concepts are promoted for the design of a floating wind turbine: a ballast stabilized floater (i.e. spar), a buoyancy stabilized floater (i.e. barge or semi-submersible) or a mooring stabilized floater (tension leg platform). In April 2011 the DeepCWind consortium visited MARIN to carry out model tests in the offshore wave basin with these three types of floating wind turbine platform. This paper reports a numerical study of a wind turbine supported by a semi-submersible floater. The response of the floating system to wind and wave conditions is compared to physical measurements at 1:50 model scale. The outcome of these comparisons is discussed in the conclusions of this paper.

Study of a Floating Foundation for Wind Turbines

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Sébastien Gueydon ◽  
Sam Weller
Keyword(s):  
Wind Turbine ◽  
Shallow Water ◽  
Numerical Study ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Farms ◽  
Physical Measurements ◽  
Floating Wind Turbine ◽  
Wave Basin ◽  
Floating System

Offshore wind farms are currently located predominantly in shallow water as it is possible to cost effectively install bottom fixed offshore turbines. Where shallow water sites are not available, floating offshore turbines could be a better solution than bottom fixed turbines. Currently three main concepts are promoted for the design of a floating wind turbine: a ballast stabilized floater (i.e., spar), a buoyancy stabilized floater (i.e., barge or semisubmersible), or a mooring stabilized floater (tension leg platform). In April 2011 the DeepCWind consortium visited MARIN to carry out model tests in the offshore wave basin with these three types of floating wind turbine platform. This paper reports a numerical study of a wind turbine supported by a semisubmersible floater. The response of the floating system to wind and wave conditions is compared to physical measurements at 1:50 model scale. The outcome of these comparisons is discussed in the conclusions of this paper.

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

Energies ◽  
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.

Comparison of Spar and Semisubmersible Floater Concepts of Offshore Wind Turbines Using Long-Term Analysis

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Hasan Bagbanci ◽  
D. Karmakar ◽  
C. Guedes Soares
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Transfer Functions ◽  
Probability Distributions ◽  
Offshore Wind ◽  
Short Term ◽  
Offshore Wind Turbines ◽  
Floating Wind Turbine ◽  
Offshore Floating Wind Turbine

The long-term probability distributions of a spar-type and a semisubmersible-type offshore floating wind turbine response are calculated for surge, heave, and pitch motions along with the side-to-side, fore–aft, and yaw tower base bending moments. The transfer functions for surge, heave, and pitch motions for both spar-type and semisubmersible-type floaters are obtained using the fast code and the results are also compared with the results obtained in an experimental study. The long-term predictions of the most probable maximum values of motion amplitudes are used for design purposes, so as to guarantee the safety of the floating wind turbines against overturning in high waves and wind speed. The long-term distribution is carried out using North Atlantic wave data and the short-term floating wind turbine responses are represented using Rayleigh distributions. The transfer functions are used in the procedure to calculate the variances of the short-term responses. The results obtained for both spar-type and semisubmersible-type offshore floating wind turbine are compared, and the study will be helpful in the assessments of the long-term availability and economic performance of the spar-type and semisubmersible-type offshore floating wind turbine.

DNV GL Standard for Floating Wind Turbines

2018 ◽  
Author(s):  
Anne Lene Haukanes Hopstad ◽  
Kimon Argyriadis ◽  
Andreas Manjock ◽  
Jarett Goldsmith ◽  
Knut O. Ronold
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Technical Specification ◽  
Oil And Gas Industry ◽  
Offshore Wind ◽  
Floating Structures ◽  
Service Specification ◽  
Technical Requirements ◽  
Floating Wind Turbine ◽  
Damage Stability

The first issue of the DNV Offshore Standard, DNV-OS-J103 Design of Floating Wind Turbine Structures, was published in June 2013. The standard was based on a joint industry effort with representatives from manufacturers, developers, utility companies and certifying bodies from Europe, Asia and the US. The standard represented a condensation of all relevant requirements for floaters in existing DNV standards for the offshore oil and gas industry which were considered relevant also for offshore floating structures for support of wind turbines, supplemented by necessary adaptation to the wind turbine application. The development of the standard capitalized much on experience from development projects going on at the time, in particular the Hywind spar off the coast of western Norway, the WindFloat off the coast of Portugal and the Pelastar TLP concept. In July 2018, DNV GL published a revision of DNV-OS-J103 as a part of the harmonization of the DNV GL codes for the wind turbine industry after the merger between Det Norske Veritas (DNV) and Germanischer Lloyd (GL) in the fall of 2013. The standard was re-issued as DNVGL-ST-0119 Floating wind turbine structures. This new revision reflects the experience gained after the first issue in 2013 as well as the current trends within the industry. Since 2013, numerous guidelines addressing the design of floating structures for offshore wind turbines have been published by various certifying bodies, and an IEC technical specification on the subject is under way. In addition, several prototypes have been installed and the first small array of floating wind turbines, Hywind Scotland pilot park, are currently in operation. The most important updates in the revision of the standard include formulation of floater-specific load cases, requirements to be fulfilled to support the exemption for design of unmanned floaters with damage stability, and replacement of current consequence-class based requirements for design fatigue factors with low-consequence based factors dependent on the accessibility for inspection and repair, the aim being a safety level against fatigue similar to that which is currently targeted for bottom-fixed structures. Other topics which have been considered in the revision are the floater motion control system and its possible integration with the control and protection system for the wind turbine, the issue of how to deal with slack in tendons in the station keeping system, corrosion, anchor design and power cable design. In parallel to the revision of the standard, a new service specification for certification of floating wind turbines has been developed by DNV GL, identified as DNVGL-SE-0422 Certification of floating wind turbines. For technical requirements, the service specification refers to the revised standard, DNVGL-ST-0119. The technical paper summarizes the updates and changes in the revised standard, in addition to the content of the new service specification.

Investigations of Unsteady Aerodynamics of an Offshore Floating Wind Turbine With Platform Motions Using Dual-Sliding Method

2020 ◽  
Author(s):  
Xiaodong Wang ◽  
Zhaoliang Ye ◽  
Ziwen Chen ◽  
Yize Guo ◽  
Yujun Qiao
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Aerodynamic Performance ◽  
Offshore Wind ◽  
Sliding Mesh ◽  
Unsteady Aerodynamic ◽  
Floating Wind Turbine ◽  
Mesh Method ◽  
Offshore Floating Wind Turbine ◽  
Platform Motions

Abstract Offshore wind energy developed rapidly in recent years. Due to the platform motions causing by ocean waves, the aerodynamics of floating offshore wind turbines (FOWT) show strong unsteady characters than onshore wind turbines. The widely used methods to investigate the unsteady aerodynamic performance of wind turbine are Blade Element Momentum (BEM) and Free-Vortex Wake (FVW) methods. The accuracy of these two methods strongly depend on empirical formula or correction models. However, for dynamics motions of wind turbine, there is still a lack of accurate models. CFD simulations using overset or dynamic mesh methods also have been used for FOWT aerodynamic investigations. However, the mesh deforming or reconstruction methods are usually suitable for small movement of wind turbine blade. In this paper, a dual-sliding mesh method is employed to simulate the unsteady aerodynamic characters of an offshore floating wind turbine with supporting platform motions using Unsteady Reynolds Averaged Navier-Stokes (URANS) simulations. Both rotor rotation and platform motions are treated as rigid angular motions. The relative motion and data exchange were simulated using sliding mesh method. The NREL 5MW reference wind turbine with platform pitching and rolling motions are considered. The pitching and rolling motions of floating platform are simplified in the form of a prescribed sinusoidal function. Different conditions with two amplitudes and two frequencies of pitching and rolling motions were investigated. URANS were performed with full structured mesh for wind turbine rotor using commercial software FLUENT. The platform motions were set using User Defined Function (UDF). Transitional Shear Stress Turbulence (T-SST) model was employed. The simulation results were compared with BEM method and FVW method results. Both steady status and dynamic pitching processes are investigated. The variations of wind turbine aerodynamic load, as well as the aerodynamic character of airfoils at different spanwise positions, were obtained and analyzed in detail. The simulations results show that the platform pitching introduce remarkable influence on the wind turbine aerodynamic performance. The platform pitching has much larger influence on the wind turbine power and thrust than the platform rolling. The dual-sliding mesh method shows potentials to investigation the dynamic process with multiple rigid motions.

scholarly journals Numerical study of various geometries of breakwaters for the installation of floating wind turbines

2016 ◽  
Vol 13 (1) ◽  
pp. 27-37 ◽  
Author(s):  
Keyvan Esmaeelpour ◽  
Rouzbeh Shafaghat ◽  
Rezvan Alamian ◽  
Rasoul Bayani
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Numerical Study ◽  
Energy Resources ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Renewable Energy Resources ◽  
Time Step ◽  
Set Up ◽  
The Right

The everyday growing populations all over the world and the necessity of increase in consumption of fossil energies have made the human to discover new energy resources, which are clean, cheap and renewable. Wind energy is one of the renewable energy resources. Considerable wind speed has made settling of wind turbines at sea beneficial and appealing. For this purpose, choosing the appropriate plates to set up wind turbines on the surface of sea is necessary. Regarding the installation condition, by choosing suitable geometry for floating breakwaters, offshore wind turbine can be mounted on them. Suitable geometry of breakwater for multifunctional usage could be selected with analyzing and comparing pressure, force and moment produced by incoming waves. In this article, we implement boundary element method to solve governing differential equations by assuming potential flow. On the other hand, for promoting free surface in each time step, we employed Euler-Lagrangian method. Finally, to find the appropriate geometry for installing the wind turbine on the breakwater, moment and wave profile next to the right and left side of breakwater body are calculated. Among simulated geometries, breakwater with trapezoid geometry which its larger base is placed in the water has more sustainability and it is the most suitable geometry for wind turbine installation.

The Current Situation and Recent Advances of Deep-Water Floating Wind Turbine

2012 ◽  
Vol 226-228 ◽  
pp. 772-775
Author(s):  
Yu Chen ◽  
Chun Li ◽  
Wei Gao ◽  
Jia Bin Nie
Keyword(s):  
Wind Turbine ◽  
Deep Water ◽  
Rapid Development ◽  
Coupled Model ◽  
Wind Farms ◽  
International Standards ◽  
Offshore Wind ◽  
Current Status ◽  
Offshore Wind Turbine ◽  
Floating Wind Turbine

Offshore wind turbine is a novel approach in the field of wind energy technology. With the rapid development of coastal wind farms, it is the trend to move them outward to deep-water district. However, the cost of construction rises significantly with the increase in water depth. Floating wind turbine is one of the efficient methods to solve this problem. The early history, current status and cutting-edge improvements of overseas offshore floating wind turbine as well as the shortcomings shall be presented. The concept designs, international standards, fully coupled model simulations and hydrodynamic experiments will be illustrated and discussed together with the development of the theory and the related software modules. Thus a novel researching method and concept shall be presented to provide reference for future researches

scholarly journals Mooring Line Damping Estimation for a Floating Wind Turbine

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Dongsheng Qiao ◽  
Jinping Ou
Keyword(s):  
Wind Turbine ◽  
Estimation Method ◽  
Excitation Amplitude ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Scale Model ◽  
Mooring Line ◽  
Offshore Wind Turbine ◽  
Floating Wind Turbine ◽  
Excitation Period

The dynamic responses of mooring line serve important functions in the station keeping of a floating wind turbine (FWT). Mooring line damping significantly influences the global motions of a FWT. This study investigates the estimation of mooring line damping on the basis of the National Renewable Energy Laboratory 5 MW offshore wind turbine model that is mounted on the ITI Energy barge. A numerical estimation method is derived from the energy absorption of a mooring line resulting from FWT motion. The method is validated by performing a 1/80 scale model test. Different parameter changes are analyzed for mooring line damping induced by horizontal and vertical motions. These parameters include excitation amplitude, excitation period, and drag coefficient. Results suggest that mooring line damping must be carefully considered in the FWT design.

Physical Model Testing of the TetraSpar Demo Floating Wind Turbine Prototype

2019 ◽  
Author(s):  
Michael Borg ◽  
Anthony Viselli ◽  
Christopher K. Allen ◽  
Matthew Fowler ◽  
Christoffer Sigshøj ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Numerical Models ◽  
Model Testing ◽  
Offshore Wind ◽  
Scale Model ◽  
Test Facility ◽  
Hydrodynamic Characteristics ◽  
Ocean Engineering ◽  
Floating Wind Turbine ◽  
Floating Offshore Wind Turbines

Abstract As part of the process of deploying new floating offshore wind turbines, scale model testing is carried out to de-risk and verify the design of novel foundation concepts. This paper describes the testing of a 1:43 Froude-scaled model of the TetraSpar Demo floating wind turbine prototype that shall be installed at the Metcentre test facility, Norway. The TetraSpar floating foundation concept consists of a floater tetrahedral structure comprising of braces connected together through pinned connections, and a triangular keel structure suspended below the floater by six suspension lines. A description of the experimental setup and program at the Alfond W2 Ocean Engineering Lab at University of Maine is given. The objective of the test campaign was to validate the initial design, and contribute to the development of the final demonstrator design and numerical models. The nonlinear hydrodynamic characteristics of the design are illustrated experimentally and the keel suspension system is shown to satisfy design criteria.

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