An Assessment of Structural Design Guidelines for Offshore Wind Turbines

2007 ◽  
Author(s):  
Rakesh K. Saigal ◽  
Dan Dolan ◽  
Armen Der Kiureghian ◽  
Tim Camp ◽  
Charles E. Smith
Keyword(s):  
Renewable Energy ◽  
Wind Turbine ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Guidance Document ◽  
Support Structures ◽  
Design Standards ◽  
Offshore Wind Farms ◽  
Design Requirements

This paper addresses the need for U.S. standards to establish design requirements for offshore wind turbine support structures. There are wind power resources in U.S. waters that can be developed to generate substantial amounts of clean, renewable energy. While a number of offshore wind farms have been proposed for U.S. waters none have been built. The U.S. Minerals Management Service and the National Renewable Energy Laboratory have recently commissioned a study to compare and benchmark the International Electrotechnical Commission (IEC) design standards with the American Petroleum Institute (API) recommended practices. Offshore wind farms that are operating in Europe have been designed using standards developed specifically for offshore wind, such as those developed by Germanischer Lloyd (GL) and Det Norske Veritas (DNV). The IEC has recently drafted design requirements specifically for offshore wind farms that provides a comprehensive definition of load conditions and references other standards, where needed, to provide a complete guidance document. The intent of this paper is to examine the range of applicability of the various design standards and to assess how these standards apply to the design of U.S. offshore wind turbine (OWT) support structures.

Effect of Foundation Modelling Methodology on the Dynamic Response of Offshore Wind Turbine Support Structures

2011 ◽  
Author(s):  
Eric Van Buren
Keyword(s):  
Wind Turbine ◽  
Dynamic Properties ◽  
Dynamic Performance ◽  
Optimization Procedure ◽  
Operating Conditions ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Support Structures ◽  
Design Standards ◽  
Modelling Methodology

When preliminarily investigating offshore wind turbine tower concepts it is common to develop optimization software for determining the best possible structural layout. This type of optimization procedure requires a large number of iterations to determine the best possible design and can be quite time consuming, particularly if the dynamic performance of each structure is to be investigated using an aero-hydro-servo-elastic type solver. When performing this type of “dynamic optimization” it is convenient to simply assume fixed boundary conditions at the soil-structure interface and ignore the dynamic properties of the foundation. Using fixed conditions allows for each of the layouts to be compared quickly and makes the computer models simple to create and more efficient in computation than if the foundation is included. Alternatively, the foundations of offshore wind turbine support structures can be represented with several different methods of varying complexity and detail. The most widely used method is the use of a distributed spring model commonly known as the p-y method. This approach is the primary method in most offshore wind turbine design standards for determining the static and cyclic reaction of offshore piles. In this work, two offshore wind support structure layouts are modeled and analyzed in the wind turbine analysis program HAWC2. Dynamic time series analyses under operating conditions are carried out for each tower with fixed conditions and with foundation models based on the p-y method in order to determine the appropriateness of utilizing fixed foundation conditions for optimization procedures.

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.

Study on the Coexistence of Offshore Wind Farms and Cage Culture

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1960
Author(s):  
Hsing-Yu Wang ◽  
Hui-Ming Fang ◽  
Yun-Chih Chiang
Keyword(s):  
Wind Turbine ◽  
Wind Power ◽  
Wind Farm ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Offshore Wind Farms ◽  
Offshore Wind Power ◽  
Waves And Currents ◽  
The Waves

In this study, a hydrodynamic model was used that includes the effects of wave–current interactions to simulate the wave and current patterns before and after offshore wind turbine installation in western Taiwan. By simulating the waves and currents after the offshore wind turbine was established, the waves and currents caused by the wind turbine were seen to have a limited range of influence, which is probably within an area about four to five times the size of the diameter (12–15 m) of the foundation structure. Overall, the analysis of the simulation results of the wave and current patterns after the offshore wind turbines were established shows that the underwater foundation only affected the local area near the pile structure. The wind farm (code E) of the research case can be equipped with about 720 cage cultures; if this is extended to other wind farms in the western sea area, it should be possible to produce economic-scale farming operations such as offshore wind power and fisheries. However, this study did not consider the future operation of the entire offshore wind farm. If the operation and maintenance of offshore wind farms are not affected, and if the consent of the developer is obtained, it should be possible to use this method to provide economically large-scale farming areas as a mutually beneficial method for offshore wind power generation and fisheries.

scholarly journals Transient LES of an offshore wind turbine

2017 ◽  
Vol 2 (2) ◽  
pp. 603-614 ◽  
Author(s):  
Lukas Vollmer ◽  
Gerald Steinfeld ◽  
Martin Kühn
Keyword(s):  
Wind Turbine ◽  
Wind Farm ◽  
Mesoscale Model ◽  
Sampling Rate ◽  
Measurement Data ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Offshore Wind Farms ◽  
Synoptic Wind

Abstract. The estimation of the cost of energy of offshore wind farms has a high uncertainty, which is partly due to the lacking accuracy of information on wind conditions and wake losses inside of the farm. Wake models that aim to reduce the uncertainty by modeling the wake interaction of turbines for various wind conditions need to be validated with measurement data before they can be considered as a reliable estimator. In this paper a methodology that enables a direct comparison of modeled with measured flow data is evaluated. To create the simulation data, a model chain including a mesoscale model, a large-eddy-simulation (LES) model and a wind turbine model is used. Different setups are compared to assess the capability of the method to reproduce the wind conditions at the hub height of current offshore wind turbines. The 2-day-long simulation of the ambient wind conditions and the wake simulation generally show good agreements with data from a met mast and lidar measurements, respectively. Wind fluctuations due to boundary layer turbulence and synoptic-scale motions are resolved with a lower representation of mesoscale fluctuations. Advanced metrics to describe the wake shape and development are derived from simulations and measurements but a quantitative comparison proves to be difficult due to the scarcity and the low sampling rate of the available measurement data. Due to the implementation of changing synoptic wind conditions in the LES, the methodology could also be beneficial for case studies of wind farm performance or wind farm control.

scholarly journals Scour Controlling Effect of Hybrid Mono-Pile as a Substructure of Offshore Wind Turbine: A Numerical Study

2020 ◽  
Vol 8 (9) ◽  
pp. 637 ◽  
Author(s):  
Yong-Jun Cho
Keyword(s):  
Wind Turbine ◽  
Numerical Study ◽  
Standing Waves ◽  
Wind Farms ◽  
Horseshoe Vortex ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Control Effect ◽  
Incoming Wave ◽  
Offshore Wind Farms

In Europe, which has been operating offshore wind farms well ahead of South Korea, most offshore wind turbines installed in shallow waters are suffering from severe scouring problems due to the horseshoe vortex. These operating experiences can serve as a valuable lesson for Korea. After a thorough review, we conclude that the horseshoe vortex’s intensity is proportional to the height of the standing waves near an offshore wind turbine. Based on this rationale, we propose a hybrid mono-pile, which is a mono-pile with an additional light turbine mounted at its toe that can dissipate the incoming wave energy with the rotation that occurs when the turbine is exposed to incoming waves or currents. The weakened standing waves in this manner would lead to less sediment transport. We proceeded to carry out the numerical simulation to verify the scouring control effect of the hybrid mono-pile. Numerical results show that the hybrid mono-pile could reduce scouring remarkably.

Ship Impact Behavior on Jacket Type Offshore Wind Turbine Foundation

2014 ◽  
Author(s):  
Jianhua Zhang ◽  
Dianwei Gao ◽  
Ke Sun ◽  
Zhiyang Zhang
Keyword(s):  
Wind Turbine ◽  
Wind Farms ◽  
Offshore Wind ◽  
Impact Behavior ◽  
Offshore Wind Turbine ◽  
Power Structures ◽  
Offshore Structure ◽  
Offshore Wind Farms ◽  
Practical Engineering ◽  
Special Location

Jacket is an ideal supporting structure for large 4 to 6 MW offshore wind turbine (OWT) in deep sea. However, Due to the harsh marine environment, as well as offshore wind farms are mostly located near a busy waterway, it is inevitable that ships crash offshore wind power structures. Sometimes, collision accidents may result in severe damage in the support structure. To study the collision behavior of jacket offshore structure, dynamic characteristics of the jacket OWT foundation is analyzed in this paper, based on ADINA explicit dynamic analysis method, considering different ship speed, impact locations and joint thickness. Based on the numerical results, the joints are reinforced in special location to meet requirements. Structural performances of jacket type OWT foundation under ship impact are studied. The research results in the paper can provide the reference for practical engineering design.

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