New Design Proposal for the TLP Type Offshore Wind Turbines

2013 ◽  
Author(s):  
Yasunori Nihei ◽  
Midori Matsuura ◽  
Motohiko Murai ◽  
Kazuhiro Iijima ◽  
Tomoki Ikoma
Keyword(s):  
Wind Turbines ◽  
Oil And Gas ◽  
Design Method ◽  
Offshore Wind ◽  
Wave Forces ◽  
Oil And Gas Development ◽  
Offshore Wind Turbines ◽  
Motion Characteristics ◽  
Set Up ◽  
High Set

In this paper, we will show a new proposal to design a Tension Leg Platform (TLP) type offshore wind turbines. Generally, TLPs are used in deepwater oil and gas development fields due to their favorable motion characteristics. In this field, they have high set up costs. An upper structure of 5MW wind turbine, however, is only 450tons at its total weight, which is much lighter than that of oil and gas platforms. Therefore the displacement and water plane area of the platform might be smaller. As a result, wave forces could decrease and it could lead initial tensions to be lower. This idea that leads to low set up costs was discussed in our previous paper. Principal particulars of TLP prototypes was proposed and a tank test with both waves and wind that used 1/100 scale models was examined in the previous paper. Capsizing could be observed based on the conventional design method. So we reason why and how this capsizing occured in this paper. Also we propose new design process and new TLP prototypes based on this process.

An Approach for the Optimum Design of TLP Type Offshore Wind Turbines

2011 ◽  
Author(s):  
Yasunori Nihei ◽  
Midori Matsuura ◽  
Hiroyuki Fujioka ◽  
Hideyuki Suzuki
Keyword(s):  
Wind Turbine ◽  
Oil And Gas ◽  
Turbine Blades ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wave Forces ◽  
Oil And Gas Development ◽  
Motion Characteristics ◽  
Set Up ◽  
High Set

In this paper, we will show a new approach to design a Tension Leg Platform (TLP) type offshore wind turbine. Generally, TLPs are used in deepwater oil and gas development fields due to their favorable motion characteristics. In this field, they have high set up costs. An upper structure of 5MW wind turbine, however, is only 450tons at its total weight, which is much lighter than that of oil and gas platforms. Therefore the displacement and water plane area of the platform might be smaller. As a result, wave forces could decrease and it could lead initial tensions to be lower. This idea that leads to low set up costs will be discussed and also principal particulars of two types of TLP prototypes will be proposed in the present work. A tank test using 1/100 scale models was conducted under combined wind and wave conditions in this work. We measured not only motion characteristics, tensions on tendons, but also rotation speed of the turbine blades. Important phenomena in terms of a gyro effect, snapping and so on could be observed, and will be introduced in this paper.

Designing Process and Motion Characteristics of Spar Type Offshore Wind Turbines

2013 ◽  
Author(s):  
Yasunori Nihei ◽  
Tomoki Ikoma ◽  
Minori Kozen ◽  
Fumiya Sato ◽  
Motohiko Murai ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Oil And Gas ◽  
Type Structure ◽  
Offshore Wind ◽  
Scale Model ◽  
Offshore Wind Turbine ◽  
Offshore Wind Turbines ◽  
Motion Characteristics

In this paper, we will discuss about the designing process and the motion characteristics of the spar type offshore wind turbines. When considering a spar type structure for offshore wind turbines, it is important to take a lot of elements into consideration which have not yet been considered in the case of oil and gas platforms. In this research, we used the following standards to conduct our tests. The limit of the heel angle was 5 degrees when the wind turbines are generating in the rated state. When designing the substructure for this research we have decided to go with a substructure that operates in depth of 100m or more. Following the conditions above we have designed the spar type offshore wind turbine used for this research. In order to compare the simulated result we have created a scale model and performed tank tests under various conditions. Also we observed unexpected motion characteristics in certain mooring arrangement. So we will touch these subjects in this paper.

Detailed Study on Breaking Wave Interactions With a Jacket Structure Based on Experimental Investigations

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Jithin Jose ◽  
Olga Podrażka ◽  
Ove Tobias Gudmestad ◽  
Witold Cieślikiewicz
Keyword(s):  
Wind Turbines ◽  
Wave Breaking ◽  
Offshore Structures ◽  
Offshore Wind ◽  
Wave Forces ◽  
Breaking Wave ◽  
Offshore Wind Turbines ◽  
Wave Parameters ◽  
Wave Slamming ◽  
Breaking Wave Forces

Wave breaking is one of the major concerns for offshore structures installed in shallow waters. Impulsive breaking wave forces sometimes govern the design of such structures, particularly in areas with a sloping sea bottom. Most of the existing offshore wind turbines were installed in shallow water regions. Among fixed-type support structures for offshore wind turbines, jacket structures have become popular in recent times as the water depth for fixed offshore wind structures increases. However, there are many uncertainties in estimating breaking wave forces on a jacket structure, as only a limited number of past studies have estimated these forces. Present study is based on the WaveSlam experiment carried out in 2013, in which a jacket structure of 1:8 scale was tested for several breaking wave conditions. The total and local wave slamming forces are obtained from the experimental measured forces, using two different filtering methods. The total wave slamming forces are filtered from the measured forces using the empirical mode decomposition (EMD) method, and local slamming forces are obtained by the frequency response function (FRF) method. From these results, the peak slamming forces and slamming coefficients on the jacket members are estimated. The breaking wave forces are found to be dependent on various breaking wave parameters such as breaking wave height, wave period, wave front asymmetry, and wave-breaking positions. These wave parameters are estimated from the wave gauge measurements taken during the experiment. The dependency of the wave slamming forces on these estimated wave parameters is also investigated.

Structural Analysis of a Hybrid Substructure With Multi-Cylinder for 5MW Offshore Wind Turbines

2014 ◽  
Author(s):  
Min-Su Park ◽  
Youn-Ju Jeong ◽  
Young-Jun You
Keyword(s):  
Free Surface ◽  
Structural Analysis ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Expansion Method ◽  
Wave Force ◽  
Offshore Wind ◽  
Wave Forces ◽  
Offshore Wind Turbines ◽  
Scattering Wave

The substructure for offshore wind turbines is strongly influenced by the effect of wave forces as the size of substructure increases. Therefore, it is very important to reduce the wave force acting on substructures. In the present study the hybrid substructure, which is composed of a multi-cylinder having different radius near free surface and a gravity substructure at the bottom of multi-cylinder, is suggested to reduce the wave forces. The fluid domain is divided into two regions to calculate the wave forces acting on the hybrid substructure with multi-cylinder and the scattering wave in each fluid region is expressed by an Eigen-function expansion method. The comparison between the mono pile and the hybrid substructure is made for wave forces. Using the wave forces obtained from this study, the structural analysis of hybrid substructure is carried out through ANSYS mechanical. In order to investigate the resonance between the wind turbine and the hybrid substructure, the modal analysis is also carried out.

Linear Stability Control of Offshore Wind Turbines

2010 ◽  
Author(s):  
Christine A. Mecklenborg ◽  
Philipp Rouenhoff ◽  
Dongmei Chen
Keyword(s):  
Wind Turbines ◽  
Deep Water ◽  
Fossil Fuels ◽  
Wind Farms ◽  
Stability Control ◽  
Offshore Wind ◽  
Wave Forces ◽  
Offshore Wind Farms ◽  
Offshore Wind Turbines ◽  
Strong Winds

Offshore wind farms in deep water are becoming an attractive prospect for harnessing renewable energy and reducing dependence on fossil fuels. One area of major concern with offshore wind turbines is stability control. The same strong winds that give deep water turbines great potential for energy capture also pose a threat to stability, along with potentially strong wave forces. We examine development of state space controllers for active stabilization of a spar-buoy floating turbine. We investigate linear state feedback with a state observer and evaluate response time and disturbance rejection of decoupled SISO controllers.

Demonstration of the Intelligent Mooring System for Floating Offshore Wind Turbines

2019 ◽  
Author(s):  
Magnus J. Harrold ◽  
Philipp R. Thies ◽  
Peter Halswell ◽  
Lars Johanning ◽  
David Newsam ◽  
...  
Keyword(s):  
Wind Turbines ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Offshore Wind ◽  
Mooring System ◽  
Gas Industry ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Physical Testing ◽  
Line Loads

Abstract Existing mooring systems for floating offshore wind turbines are largely based on designs from the oil and gas industry. Even though these can ensure the safe station keeping of the floating wind platform, the design of the mooring system is currently largely conservative, leading to additional expense in an industry striving to achieve cost reduction. Recent interest in the usage of mooring materials with non-linear stiffness has shown that they have the potential to reduce peak line loads, ultimately reducing cost. This paper reports on the combined physical testing and numerical modeling of a hydraulic-based mooring component with these characteristics. The results suggest that the inclusion of the component as part of the OC4 semi-submersible platform can reduce the peak line loads by 10%. The paper also discusses a number of challenges associated with modeling and testing dynamic mooring materials.

Numerical Analysis of a Gravity Substructure for 5MW Offshore Wind Turbines due to Soil Conditions

2015 ◽  
Author(s):  
Min-Su Park ◽  
Youn-Ju Jeong ◽  
Young-Jun You ◽  
Du-Ho Lee ◽  
Byeong-Cheol Kim
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Soil Structure ◽  
Offshore Wind ◽  
Soil Structure Interaction ◽  
Structural Safety ◽  
Soil Conditions ◽  
Wave Forces ◽  
Offshore Wind Turbines ◽  
Structure Interaction

In order to increase the gross generation of wind turbines, the size of a tower and a rotor-nacelle becomes larger. In other words, the substructure for offshore wind turbines is strongly influenced by the effect of wave forces as the size of substructure increases. In addition, since a large offshore wind turbine has a heavy dead load, the reaction forces on the substructure become severe, thus very firm foundations should be required. Therefore, the dynamic soil-structure interaction has to be fully considered and the wave acting on substructure accurately calculated. In the present study ANSYS AQWA is used to evaluate the wave forces. The wave forces and wave run up on the substructure are presented for various wave conditions. Moreover, the substructure method is applied to evaluate the effect of soil-structure interaction. Using the wave forces and stiffness and damping matrices obtained from this study, the structural analysis of the gravity substructure is carried out through ANSYS mechanical. The structural behaviors of the strength and deformation are evaluated to investigate an ultimate structural safety and serviceability of gravity substructure for various soil conditions. Also, the modal analysis is carried out to investigate the resonance between the wind turbine and the gravity substructure.

WindFloat: A Floating Foundation for Offshore Wind Turbines—Part I: Design Basis and Qualification Process

2009 ◽  
Author(s):  
Dominique Roddier ◽  
Christian Cermelli ◽  
Alla Weinstein
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Oil And Gas ◽  
Large Diameter ◽  
Offshore Wind ◽  
Site Location ◽  
Offshore Wind Turbines ◽  
Design Basis ◽  
Floating Foundation ◽  
Visual Impacts

This paper and the corresponding hydrodynamic and structural study paper (also in these proceedings) summarize the feasibility study conducted for the WindFloat technology. The WindFloat is a 3-legged floating foundation for very large offshore wind turbines. It is designed to accommodate a wind turbine, 5 MW or larger, on one of the columns of the hull with minimal modifications to the tower, nacelle and turbine. Technologies for floating foundations for offshore wind turbines are evolving. It is agreed by most experts that the offshore wind industry will see a significant increase in activity in the near future. Fixed offshore turbines are limited in water depth to approximately 30∼50m. Market transition to deeper waters is inevitable, provided suitable technologies can be developed. Despite the increase in complexity, a floating foundation offers distinct advantages: • Flexibility in site location. • Access to superior wind resources further offshore. • Ability to locate in coastal regions with limited shallow continental shelf. • Ability to locate further offshore to eliminate visual impacts. • An integrated structure, without a need to redesign the mast foundation connection for every project. • Simplified offshore installation procedures. Anchors are significantly cheaper to install than fixed foundations and large diameter towers. This paper focuses on the design basis for wind turbine floating foundations, and explores the requirements that must be addressed by design teams in this new field. It shows that the design of the hull for a large wind turbine must draw on the synergies with oil and gas offshore platform technology, while accounting for the different design requirements and functionality of the wind turbine.

Study of Landing and Lift-Off Operation for Wind Turbine Components on a Ship Deck

2012 ◽  
Author(s):  
Mateusz Graczyk ◽  
Peter Christian Sandvik
Keyword(s):  
Wind Turbines ◽  
Vertical Motion ◽  
Offshore Wind ◽  
Factors Affecting ◽  
Offshore Wind Turbines ◽  
Maintenance Work ◽  
Lift Off ◽  
Motion Characteristics ◽  
Light Components ◽  
Lifting System

Access to offshore wind turbines is much more challenging and costly than for the land-based turbines. One of the factors affecting choice of the vessel to perform the maintenance work is its performance in waves. Performance of two different ships that may be used for exchange of light components for offshore wind turbines is analyzed. Vertical motion characteristics (displacement and velocity) and forces/accelerations acting on such components and lifting system during lift-off and disposal operation are investigated. Based on the analysis performed for a monohull and a catamaran, limiting sea-states are calculated and weather windows allowing for performing exchange operations are identified.

A Conceptual Design Method for Parametric Study of Blades for Offshore Wind Turbines

2011 ◽  
Author(s):  
Lars Fro̸yd ◽  
Ole G. Dahlhaug
Keyword(s):  
Wind Turbines ◽  
Design Method ◽  
Design Procedure ◽  
Rotor Blades ◽  
Offshore Wind ◽  
Offshore Wind Turbines ◽  
Integrated Method ◽  
Horizontal Axis Wind Turbines ◽  
Parametric Studies ◽  
The Time Domain

This article presents a simplified, integrated method for design studies of blades for offshore wind turbines. The method applies to variable speed horizontal axis wind turbines with pitch control, and allows designing the rotor blades based on a very limited set of input parameters. The purpose of the method is to allow parametric studies of different design configurations of the rotor at a reasonable effort. The resulting wind turbine models are at a level of detail suitable for preliminary design considerations using e.g. aero-elastic simulations in the time domain. The aerodynamic design is based on blade element momentum (BEM) considerations using a distribution of 2D airfoil characteristics. The structural design of the blades is based on aerodynamic forces calculated from a small number of load cases. The design procedure is facilitated by using simplified cross-section definitions and iterative approaches. The resulting blade designs are shown to compare well with data from available turbine models.

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