scholarly journals Model tests for tilting control of suction bucket foundation for offshore wind turbine with path points

2021 ◽  
Vol 21 (3) ◽  
pp. 125-132
Author(s):  
You-Seok Kim ◽  
Jong-Pil Lee
Keyword(s):  
Control Method ◽  
Wind Farms ◽  
Offshore Wind ◽  
Scale Model ◽  
Positive Pressure ◽  
Offshore Wind Turbine ◽  
Offshore Wind Farms ◽  
Bucket Foundation ◽  
Model Foundation ◽  
Ground Condition

In offshore wind farms, tilting control based on a single-basket suction bucket foundation is a significant problem. In a single-basket suction bucket foundation, the tilting control of the foundation is possible by arranging the cells inside and controlling the pressure of each cell. However, the pressure of each cell must be finely controlled. Studies on this topic have been conducted, but no specific tilting control method has been developed. This paper presents experimental model results for tilting control obtained during the installation of a suction bucket foundation consisting of three internal cells. Tilting control was performed by independently controlling the internal pressure of each cell. A 1:100 scale model was used, and the ground condition was sandy. Four cases of tilting control tests for the model foundation were used with multiple combinations of internal positive, negative, or both pressures of each cell. It was found that the tilting control was within 5° during the installation and operation stages. There was a tilting control limit for operation based on the model with only negative pressure; therefore, 5° tilting control was achieved by combining the positive pressure.

Optimization of O&M for Offshore Wind Farms Modelling for WMTC Conferences

2015 ◽  
Author(s):  
Thomas Nivet ◽  
Ema Muk-Pavic
Keyword(s):  
Wind Farm ◽  
Wind Farms ◽  
Cost Effective ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Offshore Wind Farms ◽  
Climate Conditions ◽  
Operation Analysis ◽  
Cost Effective Approach ◽  
Failure Evaluation

Offshore wind energy is one of the most upcoming sources of energy, and it is already partially replacing the fossil fuelled power production. However, offshore wind turbine technology is also associated with harsher weather environment. Indeed, it experiences more challenging wind and wave conditions, which in turn limits the vessels capabilities to access the wind farms. Additionally, with the constant rise of power utilization, improvements in the Operation Maintenance (O&M) planning are crucial for the development of large isolated offshore wind farms. Improvements in the planning of the O&M for offshore wind farms could lead to considerable reduction in costs. For this reason, the interest of this research paper is the investigation of the most cost effective approach to offshore turbine maintenance strategies. This objective is achieved by implementing a simulation approach that includes a climate conditions analysis, an operation analysis, a failure evaluation and a simulation of the repairs. This paper points out how different O&M strategies can influence the sustainability of a wind farm.

Value of site-specific information for the design of offshore wind farms

2019 ◽  
Author(s):  
Jorge Mendoza Espinosa ◽  
Jochen Köhler
Keyword(s):  
Safety Margin ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Specific Information ◽  
Offshore Wind Farms ◽  
Site Specific ◽  
A Value ◽  
Probabilistic Characterization ◽  
Clear Guideline

<p>Monopiles are the most common offshore wind turbine support structures. They are to be designed so that resonance with the rotor-passing excitation is avoided. However, the estimation of the eigenfrequencies is strongly influenced by the soil-structure interaction, whose characterization with prior information is associated with large uncertainties. No clear guideline is given regarding the safety margin to be left between the structure first natural frequency and the excitation regions. In this paper, the expected consequences of leaving a certain margin are studied and quantified. The decisions regarding the investment in site-specific characterization are coupled into the decision scenario by means of a value of information analysis. The results provide insight on the efficient allocation of resources at the design point in time and the sensitivity of the decisions regarding the probabilistic characterization of the design scenario.</p>

scholarly journals Stability Analysis of the Floating Offshore Wind Turbine Support Structure of Cell Spar Type during its Installation

2019 ◽  
Vol 26 (4) ◽  
pp. 109-116
Author(s):  
Paweł Dymarski ◽  
Czesław Dymarski ◽  
Ewelina Ciba
Keyword(s):  
Stability Analysis ◽  
Wind Farms ◽  
Offshore Wind ◽  
Design And Technology ◽  
Offshore Wind Turbine ◽  
Ocean Engineering ◽  
Support Structure ◽  
Offshore Wind Farms ◽  
University Of Technology ◽  
The Stability

Abstract The article presents the results of selected works related to the wider subject of the research conducted at the Faculty of Ocean Engineering and Ship Technology of the Gdansk University of Technology, which concerns design and technology of construction, towing, and settlement on the seabed, or anchoring, of supporting structures for offshore wind farms. As a result of this research, several designs of this type of objects were developed, including two stationary types: gravitational and Jack-up, which are placed on the seabed, and two floating types: TLP and SPAR, anchored with tendons and anchors in the form of nailed or suction piles. Below presented is the stability analysis of the new floating CELL SPAR type support structure for offshore wind turbines during its installation in waters with a depth of over 65 m.

scholarly journals Reliability Analysis on One-Step Overall Transportation of Composite Bucket Foundation for Offshore Wind Turbine

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 23
Author(s):  
Jijian Lian ◽  
Pengwen Wang ◽  
Conghuan Le ◽  
Xiaofeng Dong ◽  
Xu Yang ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Wind Farms ◽  
Frequency Domain Analysis ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Observation Data ◽  
Offshore Wind Farms ◽  
One Step ◽  
The One ◽  
Installation Technology

Composite bucket foundations, which have been successfully transported, installed, and operated at the Qidong, Xiangshui, and Dafeng offshore wind farms in China, are economically advantageous due to the relatively simple transportation and installation process. The innovative one-step transportation and installation technology of foundation-tower-nacelle is the key phase in saving costs. In this paper, a “foundation lift ship” overall transport mode is proposed and introduced for the first time. Prototype data measurement, preliminary numerical simulation, and theoretical calculations were conducted to investigate whether the foundation-ship integrity, tower hoop stability, and various indexes of the nacelle met the requirements under the influences of various environmental factors. The multi-system coupling motion mechanism and analysis method of this new structure and transportation mode were expounded. Through the prototype observation data of the one-step overall transportation, the ship-foundation system reliability of the structure in the case of large wind and wave was confirmed. Furthermore, it was found that in the one-step overall transportation, the importance of factors to nacelle acceleration decreased in the order of wave height, current speed, and wind speed by the time and frequency domain analysis and data statistics.

Systematic Testing of the Fatigue Performance of Submerged Small-Scale Grouted Joints

2015 ◽  
Author(s):  
Peter Schaumann ◽  
Alexander Raba
Keyword(s):  
Wind Farms ◽  
Fatigue Tests ◽  
Load Level ◽  
Fatigue Performance ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Small Scale ◽  
Loading Frequency ◽  
Surrounding Water ◽  
Offshore Wind Farms

With an increasing demand for renewable energy, offshore wind farms become more and more important. Within the next 15 years the German government intends to realize offshore wind farms with a capacity of 15 GW of electrical energy. This corresponds to approximately 3000 to 4000 new turbines. The grouted joint is a common structural detail for the connection between substructure and foundation piles in offshore wind turbine structures. For lattice substructures such as jackets, the connection is located just above the seabed and is permanently surrounded by water. Prior investigations by Schaumann et al. showed that the surrounding water may have an impact on the fatigue performance of grouted joint specimens. Thus far, very few results of submerged fatigue tests on grouted joint specimens are published and their statistical reliability is insecure. Within this paper, 24 individual test results are presented. Regarding test parameters, the focus is set on two different applied load levels, two different loading frequencies and two different grout materials. All parameters are varied in a factorial experiment and are statistically evaluated. The evaluation shows that load level and loading frequency have a significant effect on the fatigue performance of the connection. Moreover, both effects are significantly correlated. For the used grout materials no significant impact is visible, which can be explained by their similarity regarding mechanical properties and micro structure. Furthermore, the mean displacement and the stiffness degradation of the specimens during fatigue tests are discussed in detail in the paper. In conclusion, previously published results on the fatigue performance of submerged small scale grouted joint specimens can be confirmed. Load level as well as loading frequency can be stated as most relevant parameters for the fatigue performance.

scholarly journals Concrete Support Structures for Offshore Wind Turbines: Current Status, Challenges, and Future Trends

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1995
Author(s):  
Alexandre Mathern ◽  
Christoph von der Haar ◽  
Steffen Marx
Keyword(s):  
Wind Turbines ◽  
Wind Farms ◽  
Steel Structures ◽  
Production Costs ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Future Trends ◽  
Support Structures ◽  
Offshore Wind Farms ◽  
New Developments

Today’s offshore wind turbine support structures market is largely dominated by steel structures, since steel monopiles account for the vast majority of installations in the last decade and new types of multi-leg steel structures have been developed in recent years. However, as wind turbines become bigger, and potential sites for offshore wind farms are located in ever deeper waters and ever further from the shore, the conditions for the design, transport, and installation of support structures are changing. In light of these facts, this paper identifies and categorizes the challenges and future trends related to the use of concrete for support structures of future offshore wind projects. To do so, recent advances and technologies still under development for both bottom-fixed and floating concrete support structures have been reviewed. It was found that these new developments meet the challenges associated with the use of concrete support structures, as they will allow the production costs to be lowered and transport and installation to be facilitated. New technologies for concrete support structures used at medium and great water depths are also being developed and are expected to become more common in future offshore wind installations. Therefore, the new developments identified in this paper show the likelihood of an increase in the use of concrete support structures in future offshore wind farms. These developments also indicate that the complexity of future support structures will increase due to the development of hybrid structures combining steel and concrete. These evolutions call for new knowledge and technical know-how in order to allow reliable structures to be built and risk-free offshore installation to be executed.

scholarly journals The Influence of Selected Strain-Based Failure Criteria on Ship Structure Damage Resulting from a Collision with an Offshore Wind Turbine Monopile

2021 ◽  
Vol 28 (4) ◽  
pp. 42-52
Author(s):  
Karol Niklas ◽  
Alicja Bera
Keyword(s):  
Wind Turbine ◽  
Strain Curve ◽  
Wind Farms ◽  
Linear Representation ◽  
Failure Criteria ◽  
Green Energy ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Offshore Wind Farms ◽  
Structure Damage

Abstract Offshore wind farms are developing well all over the world, providing green energy from renewable sources. The evaluation of possible consequences of a collision involves Finite Element computer simulations. The goal of this paper was to analyse the influence of selected strain-based failure criteria on ship damage resulting from a collision with an offshore wind turbine monopile. The case of a collision between an offshore supply vessel and a monopile-type support structure was examined. The results imply that simulation assumptions, especially the failure criteria, are very important. It was found that, using the strain failure criteria according to the minimum values required by the design rules, can lead to an underestimation of the ship damage by as much as 6 times, for the length of the hull plate, and 9 times, for the area of the ship hull opening. Instead, the adjusted formula should be used, taking into account both the FE element size and the shell thickness. The influence of the non-linear representation of the stress-strain curve was also pointed out. Moreover, a significant influence of the selected steel grade on collision damages was found.

Monitor Method of Offshore Wind Turbine Based on Memory-Like and Neural Network Expert System

2014 ◽  
Vol 635-637 ◽  
pp. 687-693
Author(s):  
Ling Xia Su ◽  
Xia Xia Ma
Keyword(s):  
Fault Diagnosis ◽  
Wind Turbine ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Offshore Wind Farms ◽  
Onshore Wind ◽  
Diagnosis Method ◽  
Simulation Results ◽  
Improve Reliability

The number of offshore wind farms increases gradually because of the high capability of power generation. However, the costs of manufacturing, logistics, installation and maintenance of offshore wind turbine are higher than those of onshore wind turbine. Thus the introduction of fault diagnosis is considered as a suitable way to improve reliability of wind turbine and reduce costs of repairs and casualties. In this paper, 3 major failures of direct-driven wind turbine according to urgency and system responses are discussed. A "memory-like" model pretreatment method and a fault diagnosis method for the failures are investigated. The simulation results show that total amount of fault data to be processed and stored is reduced, and difficulties of knowledge gaining and fault reasoning are also decreased.

scholarly journals Simplified Floating Wind Turbine for Real-Time Simulation of Large-Scale Floating Offshore Wind Farms

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4571
Author(s):  
Thanh-Dam Pham ◽  
Minh-Chau Dinh ◽  
Hak-Man Kim ◽  
Thai-Thanh Nguyen
Keyword(s):  
Wind Turbine ◽  
Real Time ◽  
Large Scale ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Offshore Wind Farms ◽  
Real Time Simulation ◽  
The Real ◽  
Time Simulation

Floating offshore wind has received more attention due to its advantage of access to incredible wind resources over deep waters. Modeling of floating offshore wind farms is essential to evaluate their impacts on the electric power system, in which the floating offshore wind turbine should be adequately modeled for real-time simulation studies. This study proposes a simplified floating offshore wind turbine model, which is applicable for the real-time simulation of large-scale floating offshore wind farms. Two types of floating wind turbines are evaluated in this paper: the semi-submersible and spar-buoy floating wind turbines. The effectiveness of the simplified turbine models is shown by a comparison study with the detailed FAST (Fatigue, Aerodynamics, Structures, and Turbulence) floating turbine model. A large-scale floating offshore wind farm including eighty units of simplified turbines is tested in parallel simulation and real-time software (OPAL-RT). The wake effects among turbines and the effect of wind speeds on ocean waves are also taken into account in the modeling of offshore wind farms. Validation results show sufficient accuracy of the simplified models compared to detailed FAST models. The real-time results of offshore wind farms show the feasibility of the proposed turbine models for the real-time model of large-scale offshore wind farms.

scholarly journals Analysis of rotorcraft wind turbine wake encounters using piloted simulation

2021 ◽  
Author(s):  
Alexander Štrbac ◽  
Tanja Martini ◽  
Daniel H. Greiwe ◽  
Frauke Hoffmann ◽  
Michael Jones
Keyword(s):  
Wind Turbine ◽  
Alternative Energy ◽  
Wind Farm ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Vortex Wake ◽  
Offshore Wind Farms ◽  
Turbine Wake ◽  
Wind Turbine Wake

AbstractThe use of offshore wind farms in Europe to provide a sustainable alternative energy source is now considered normal. Particularly in the North Sea, a large number of wind farms exist with a significant distance from the coast. This is becoming standard practice as larger areas are required to support operations. Efficient transport and monitoring of these wind farms can only be conducted using helicopters. As wind turbines continue to grow in size, there is a need to continuously update operational requirements for these helicopters, to ensure safe operations. This study assesses German regulations for flight corridors within offshore wind farms. A semi-empirical wind turbine wake model is used to generate velocity data for the research flight simulator AVES. The reference offshore wind turbine NREL 5 MW has been used and scaled to represent wind turbine of different sizes. This paper reports result from a simulation study concerning vortex wake encounter during offshore operations. The results have been obtained through piloted simulation for a transport case through a wind farm. Both subjective and objective measures are used to assess the severity of vortex wake encounters.

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