scholarly journals Seismic Fragility Assessment of a Novel Suction Bucket Foundation for Offshore Wind Turbine under Scour Condition

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 499
Author(s):  
Duc-Vu Ngo ◽  
Young-Jin Kim ◽  
Dong-Hyawn Kim
Keyword(s):  
Horizontal Displacement ◽  
Offshore Wind ◽  
Seismic Fragility ◽  
Offshore Wind Turbine ◽  
Environmental Condition ◽  
Offshore Wind Turbines ◽  
Displacement Capacity ◽  
Foundation Model ◽  
The Stability ◽  
External Loads

This study proposed a new suction bucket (SB) foundation model for offshore wind turbines (OWT) suitable for a shallow muddy seabed, using more than three single buckets through kinetic derivation. The performance of new optimal foundation was evaluated by its horizontal displacement capacity and compared with a conventional SB composed of three buckets. Under external loads such as earthquakes, wind, and the combination of the both, the stability of this novel SB foundation was verified. The seismic fragility curve was also evaluated at some scour depths. These results were compared with the response of a tripod suction bucket (TSB) foundation, which was also designed for a shallow muddy seabed. The results indicated that scour significantly changed the dynamic response of this novel SB foundation but it had a better bearing capacity than the TSB foundation, despite its smaller size and weight. The fragility of TSB is always higher than the developed foundation in the same environmental condition. With reasonable volume and size, this novel SB foundation has great potential for future industrialization and commercialization.

The Influence of Foundation Modeling Assumptions on Long-Term Load Prediction for Offshore Wind Turbines

2008 ◽  
Author(s):  
Erica Bush ◽  
Puneet Agarwal ◽  
Lance Manuel
Keyword(s):  
Wind Turbine ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Load Prediction ◽  
Offshore Wind Turbines ◽  
Extreme Loads ◽  
Foundation Model ◽  
Flexible Foundation ◽  
Ultimate Limit

In evaluating ultimate limit states for design, time-domain aeroelastic response simulations are typically carried out to establish extreme loads on offshore wind turbines. Accurate load prediction depends on proper modeling of the wind turbulence and the wave stochastic processes as well as of the turbine, the support structure, and the foundation. One method for modeling the support structure is to rigidly connect it to the seabed; such a foundation model is appropriate only when the sea floor is firm (as is the case for rock). To obtain realistic turbine response dynamics for softer soils, it is important that a flexible foundation is modeled. While a single discrete spring for coupled lateral/rotational motion or several distributed springs along the length of the monopile may be employed, a tractable alternative is to employ a fictitious fixed-based pile modeled as an “equivalent” cantilever beam, where the length of this fictitious pile is determined using conventional pile lateral load analysis in combination with knowledge of the soil profile. The objective of this study is to investigate the influence of modeling flexible pile foundations on offshore wind turbine loads such as the fore-aft tower bending moment at the mudline. We employ a utility-scale 5MW offshore wind turbine model with a 90-meter hub height in simulations; the turbine is assumed to be sited in 20 meters of water. For a critical wind-wave combination known to control long-term design loads, we study time histories, power spectra, response statistics, and probability distributions of extreme loads for fixed-base and flexible foundation models with the intention of assessing the importance of foundation model selection. Load distributions are found to be sensitive to foundation modeling assumptions. Extrapolation to rare return periods may be expected to lead to differences in derived nominal loads needed in ultimate limit state design; this justifies the use of flexible foundation models in simulation studies.

A Novel Concept for Self Installing Offshore Wind Turbines

2013 ◽  
Author(s):  
Kasper Wåsjø ◽  
Jorge Vicente Bermúdez Rico ◽  
Morten Bjerkås ◽  
Tore Søreide
Keyword(s):  
Cost Saving ◽  
Wind Turbine ◽  
Early Phase ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Offshore Wind Turbines ◽  
Steel Jacket ◽  
The Stability ◽  
Novel Concept ◽  
The Cost

The present paper describes a novel concept of a self-installing offshore wind turbine. A concept for combined installation of the substructure and turbine in one single operation without the need of expensive installation vessels is described. The stability of the concept during transport and installation is obtained by two structurally connected standard barges with dimension 92 × 32 m. The concept proves to be stable with weather window equal HS = 4 m for transport and Hs = 1.5 m for installation in the waiting of more accurate analyses. A cost saving potential in this early phase of 17% is identified compared to the more common steel jacket solution. The cost saving is related to the installation process.

scholarly journals Maintenance Planning of Offshore Wind Turbine Using Condition Monitoring Information

2009 ◽  
Author(s):  
Jose´ G. Rangel-Rami´rez ◽  
John D. So̸rensen
Keyword(s):  
Condition Monitoring ◽  
Wind Turbines ◽  
Wind Farm ◽  
Offshore Structures ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Maintenance Planning ◽  
Offshore Wind Turbines ◽  
Inspection And Maintenance ◽  
Monitoring Information

Deterioration processes such as fatigue and corrosion are typically affecting offshore structures. To “control” this deterioration, inspection and maintenance activities are developed. Probabilistic methodologies represent an important tool to identify the suitable strategy to inspect and control the deterioration in structures such as offshore wind turbines (OWT). Besides these methods, the integration of condition monitoring information (CMI) can optimize the mitigation activities as an updating tool. In this paper, a framework for risk-based inspection and maintenance planning (RBI) is applied for OWT incorporating CMI, addressing this analysis to fatigue prone details in welded steel joints at jacket or tripod steel support structures for offshore wind turbines. The increase of turbulence in wind farms is taken into account by using a code-based turbulence model. Further, additional modes t integrate CMI in the RBI approach for optimal planning of inspection and maintenance. As part of the results, the life cycle reliabilities and inspection times are calculated, showing that earlier inspections are needed at in-wind farm sites. This is expected due to the wake turbulence increasing the wind load. With the integration of CMI by means Bayesian inference, a slightly change of first inspection times are coming up, influenced by the reduction of the uncertainty and harsher or milder external agents.

scholarly journals Improving the Strategy of Maintaining Offshore Wind Turbines through Petri Net Modelling

2021 ◽  
Vol 11 (2) ◽  
pp. 574
Author(s):  
Rundong Yan ◽  
Sarah Dunnett
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Petri Net ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Maintenance Costs ◽  
Offshore Wind Turbines ◽  
Major Repair ◽  
Wind Turbine System ◽  
Periodic Maintenance

In order to improve the operation and maintenance (O&M) of offshore wind turbines, a new Petri net (PN)-based offshore wind turbine maintenance model is developed in this paper to simulate the O&M activities in an offshore wind farm. With the aid of the PN model developed, three new potential wind turbine maintenance strategies are studied. They are (1) carrying out periodic maintenance of the wind turbine components at different frequencies according to their specific reliability features; (2) conducting a full inspection of the entire wind turbine system following a major repair; and (3) equipping the wind turbine with a condition monitoring system (CMS) that has powerful fault detection capability. From the research results, it is found that periodic maintenance is essential, but in order to ensure that the turbine is operated economically, this maintenance needs to be carried out at an optimal frequency. Conducting a full inspection of the entire wind turbine system following a major repair enables efficient utilisation of the maintenance resources. If periodic maintenance is performed infrequently, this measure leads to less unexpected shutdowns, lower downtime, and lower maintenance costs. It has been shown that to install the wind turbine with a CMS is helpful to relieve the burden of periodic maintenance. Moreover, the higher the quality of the CMS, the more the downtime and maintenance costs can be reduced. However, the cost of the CMS needs to be considered, as a high cost may make the operation of the offshore wind turbine uneconomical.

scholarly journals Impact of Typhoons on Floating Offshore Wind Turbines: A Case Study of Typhoon Mangkhut

2021 ◽  
Vol 9 (5) ◽  
pp. 543
Author(s):  
Jiawen Li ◽  
Jingyu Bian ◽  
Yuxiang Ma ◽  
Yichen Jiang
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Safety Evaluation ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Motion Response ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Coupling Motion

A typhoon is a restrictive factor in the development of floating wind power in China. However, the influences of multistage typhoon wind and waves on offshore wind turbines have not yet been studied. Based on Typhoon Mangkhut, in this study, the characteristics of the motion response and structural loads of an offshore wind turbine are investigated during the travel process. For this purpose, a framework is established and verified for investigating the typhoon-induced effects of offshore wind turbines, including a multistage typhoon wave field and a coupled dynamic model of offshore wind turbines. On this basis, the motion response and structural loads of different stages are calculated and analyzed systematically. The results show that the maximum response does not exactly correspond to the maximum wave or wind stage. Considering only the maximum wave height or wind speed may underestimate the motion response during the traveling process of the typhoon, which has problems in guiding the anti-typhoon design of offshore wind turbines. In addition, the coupling motion between the floating foundation and turbine should be considered in the safety evaluation of the floating offshore wind turbine under typhoon conditions.

scholarly journals Physical Modelling of Offshore Wind Turbine Foundations for TRL (Technology Readiness Level) Studies

2021 ◽  
Vol 9 (6) ◽  
pp. 589
Author(s):  
Subhamoy Bhattacharya ◽  
Domenico Lombardi ◽  
Sadra Amani ◽  
Muhammad Aleem ◽  
Ganga Prakhya ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Prior Experience ◽  
Physical Modelling ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Foundation Design ◽  
Offshore Wind Turbines ◽  
Sea Bed ◽  
Geological Conditions

Offshore wind turbines are a complex, dynamically sensitive structure due to their irregular mass and stiffness distribution, and complexity of the loading conditions they need to withstand. There are other challenges in particular locations such as typhoons, hurricanes, earthquakes, sea-bed currents, and tsunami. Because offshore wind turbines have stringent Serviceability Limit State (SLS) requirements and need to be installed in variable and often complex ground conditions, their foundation design is challenging. Foundation design must be robust due to the enormous cost of retrofitting in a challenging environment should any problem occur during the design lifetime. Traditionally, engineers use conventional types of foundation systems, such as shallow gravity-based foundations (GBF), suction caissons, or slender piles or monopiles, based on prior experience with designing such foundations for the oil and gas industry. For offshore wind turbines, however, new types of foundations are being considered for which neither prior experience nor guidelines exist. One of the major challenges is to develop a method to de-risk the life cycle of offshore wind turbines in diverse metocean and geological conditions. The paper, therefore, has the following aims: (a) provide an overview of the complexities and the common SLS performance requirements for offshore wind turbine; (b) discuss the use of physical modelling for verification and validation of innovative design concepts, taking into account all possible angles to de-risk the project; and (c) provide examples of applications in scaled model tests.

PyraWind™: An Innovative Floating Offshore Wind Turbine (FOWT) Global Performance Analysis

2021 ◽  
Author(s):  
Zhiyong Yang ◽  
Xiaoqiang Bian ◽  
Yu Shi
Keyword(s):  
Wind Turbine ◽  
Hydrodynamic Model ◽  
Coupled System ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Offshore Wind Turbine ◽  
Offshore Wind Turbines ◽  
Ongoing Work ◽  
Heavy Lift ◽  
Solid Foundation

Abstract In the near future, the offshore wind industry will experience a significant increase of turbine size and of floating wind development activities. A floating offshore wind turbine foundation offers many advantages, such as flexibility in site selection, access to better offshore wind resources, and quayside integration to avoid a costly heavy lift vessel offshore campaign. PyraWind™ is a patented three canted column semisubmersible floating foundation for ultra large offshore wind turbines. It is designed to accommodate a wind turbine, 14 MW or larger, in the center of the interconnected columns of the hull with minimal modifications to the tower, nacelle and turbine. The pyramid-shaped hull provides a stable, solid foundation for the large wind turbine under development. This paper summarizes the feasibility study conducted for the PyraWind™ concept. The design basis for wind turbine floating foundations is described and the regulatory requirements are discussed. Also included are the hydrodynamic analysis of the hull and ongoing work consisting of coupling hull hydrodynamics with wind-turbine aerodynamic loads. The fully coupled system was analyzed using OpenFAST, an aerodynamic software package for wind turbine analysis with the ability to be coupled with the hydrodynamic model. Due to the canted columns, a nonlinear analysis was performed using the coupled numerical hydrodynamic model of the platform with mooring system in extreme sea states.

Verification Study of CFD Simulation of Semi-Submersible Floating Offshore Wind Turbine Under Regular Waves

2021 ◽  
Author(s):  
Yu Wang ◽  
Hamn-Ching Chen ◽  
Guilherme Vaz ◽  
Simon Mewes
Keyword(s):  
Cfd Simulation ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Regular Waves ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Spatial Convergence ◽  
Goal Response ◽  
Computational Fluid Dynamics Cfd ◽  
Response Amplitude Operators

Abstract Utilization of Computational Fluid Dynamics (CFD) codes to perform hydrodynamic analysis of Floating Offshore Wind Turbines (FOWTs) is increasing recently. However, verification studies of the simulations that quantifying numerical uncertainties and permitting a detailed validation in a next phase is often disregarded. In this work, a verification study of CFD simulations of a semi-submersible FOWT design under regular waves is performed. To accomplish this goal, Response Amplitude Operators (RAOs) are derived from the computational results of the heave, surge and pitch motions. Four grids with different grid sizes with a constant refinement ratio are generated for verification of spatial convergence. Three different time increments are paired with each grid for verification of temporal convergence. The verification study is performed by estimation of the numerical errors and uncertainties using procedures proposed by Eca and Hoekstra [1].

Experimental Study on the Stability Performance and Turning Motion of Multi-Connection VAWT

2021 ◽  
Author(s):  
Saika Iwamatsu ◽  
Yasunori Nihei ◽  
Kazuhiro Iijima ◽  
Tomoki Ikoma ◽  
Tomoki Komori
Keyword(s):  
Scaling Law ◽  
Type A ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Water Tank ◽  
Type B ◽  
Floating Bodies ◽  
Stability Performance ◽  
Turning Motion ◽  
The Stability

Abstract In this study, a series of dedicated water tank tests were conducted in wind and waves to investigate the stability performance and turning motion of Floating Offshore Wind Turbine (FOWT) equipped with two vertical axis wind turbines (VAWT). The FOWT targeted in this study is called Multi-connection VAWT, which is a new type of FOWT moored by Single-Point-Mooring (SPM) system. We designed and manufactured two types of semi-submersible floating bodies. One is a type in which VAWTs are mounted in two places of a right-angled isosceles triangle (Type-A) on a single floater, and the other is two independent units equipped with VAWTs on two separate floaters centered on a moored body. This is a type in which two semi-submersible floating bodies are lined up in a straight line (Type-B). The experimental conditions were determined by scaling down to 1/100 using Froude’s scaling law based on a wind thrust load of 320 kN (rated wind speed of 12 m/s) assuming an actual machine. In the free yawing test in waves, Type-A turned downwards, while Type-B was barely affected by the waves. Furthermore, in the free yawing test in wind, both Type-A and Type-B turned leeward and stabilized at a final point where the wind load was balanced.

Sign in / Sign up

Export Citation Format

Share Document