Geological and geotechnical characterisation for offshore wind turbine foundations: A case study of the Sheringham Shoal wind farm

The experimental proof of the floating wind turbine has been started off Goto Islands in Japan. Furthermore, the project of floating wind farm is afoot off Fukushima Prof. in north eastern part of Japan. It is essential for realization of the floating wind farm to comprehend its safety, electric generating property and motion in waves and wind. The scale model experiments are effective to catch the characteristic of floating wind turbines. Authors have mainly carried out scale model experiments with wind turbine models on SPAR buoy type floaters. The wind turbine models have blade-pitch control mechanism and authors focused attention on the effect of blade-pitch control on both the motion of floater and fluctuation of rotor speed. In this paper, the results of scale model experiments are discussed from the aspect of motion of floater and the effect of blade-pitch control.

Download Full-text

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

Journal of Marine Science and Engineering ◽

10.3390/jmse9050543 ◽

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.

Download Full-text

Study on the Dynamic Response for Floating Foundation of Offshore Wind Turbine

Volume 5: Ocean Space Utilization; Ocean Renewable Energy ◽

10.1115/omae2011-50329 ◽

2011 ◽

Author(s):

Yougang Tang ◽

Jun Hu ◽

Liqin Liu

Keyword(s):

Wind Turbine ◽

Wind Farm ◽

Dynamic Responses ◽

Offshore Wind ◽

Offshore Wind Turbine ◽

Wave Load ◽

Mooring Lines ◽

Floating Foundation ◽

Wind Turbine System ◽

Sea Area

The wind resources for ocean power generation are mostly distributed in sea areas with the distance of 5–50km from coastline, whose water depth are generally over 20m. To improve ocean power output and economic benefit of offshore wind farm, it is necessary to choose floating foundation for offshore wind turbine. According to the basic data of a 600kW wind turbine with a horizontal shaft, the tower, semi-submersible foundation and mooring system are designed in the 60-meter-deep sea area. Precise finite element models of the floating wind turbine system are established, including mooring lines, floating foundation, tower and wind turbine. Dynamic responses for the floating foundation of offshore wind turbine are investigated under wave load in frequency domain.

Download Full-text

Fatigue Life Analysis of Offshore Wind Turbine Support Structures in an Offshore Wind Farm

ASME 2018 1st International Offshore Wind Technical Conference ◽

10.1115/iowtc2018-1061 ◽

2018 ◽

Author(s):

Bryan Nelson ◽

Yann Quéméner

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Wind Farm ◽

The Body ◽

Offshore Wind ◽

Offshore Wind Turbine ◽

Analysis Tool ◽

Support Structures ◽

Offshore Wind Farm ◽

Actuator Disk

This study evaluated, by time-domain simulations, the fatigue lives of several jacket support structures for 4 MW wind turbines distributed throughout an offshore wind farm off Taiwan’s west coast. An in-house RANS-based wind farm analysis tool, WiFa3D, has been developed to determine the effects of the wind turbine wake behaviour on the flow fields through wind farm clusters. To reduce computational cost, WiFa3D employs actuator disk models to simulate the body forces imposed on the flow field by the target wind turbines, where the actuator disk is defined by the swept region of the rotor in space, and a body force distribution representing the aerodynamic characteristics of the rotor is assigned within this virtual disk. Simulations were performed for a range of environmental conditions, which were then combined with preliminary site survey metocean data to produce a long-term statistical environment. The short-term environmental loads on the wind turbine rotors were calculated by an unsteady blade element momentum (BEM) model of the target 4 MW wind turbines. The fatigue assessment of the jacket support structure was then conducted by applying the Rainflow Counting scheme on the hot spot stresses variations, as read-out from Finite Element results, and by employing appropriate SN curves. The fatigue lives of several wind turbine support structures taken at various locations in the wind farm showed significant variations with the preliminary design condition that assumed a single wind turbine without wake disturbance from other units.

Download Full-text

A Comparison of Time Domain Seismic Analysis Methods for Offshore Wind Turbine Structures: Using a Superelement Approach

ASME 2019 2nd International Offshore Wind Technical Conference ◽

10.1115/iowtc2019-7562 ◽

2019 ◽

Author(s):

Laurens Alblas ◽

Corine de Winter

Keyword(s):

Rigid Body ◽

Wind Turbine ◽

Time Domain ◽

Wind Farm ◽

Assessment Tool ◽

Seismic Analysis ◽

Offshore Wind ◽

Offshore Wind Turbine ◽

Rigid Body Motions ◽

Seismic Accelerations

Abstract Recently, wind farm development has gained more traction in Asian countries such as Taiwan, which are seismically active. Compared to Europe, the offshore wind structures need to be designed for these additional extreme environmental conditions. For monopiles, these calculations can typically be performed in an integrated way in the wind turbine load calculation, but for jackets the superelement (SE) approach remains preferred. At the time of writing different approaches are being applied in the industry to apply the SE approach for seismic time domain analysis. This work explains and compares three different methods, based on calculations performed in offshore strength assessment tool Sesam and aeroelastic tool BHawC. When including additional interface nodes at the foundation model bottom into the SE to which the seismic accelerations can be applied in BHawC similarly as in the re-tracking run in Sesam, the results between BHawC and Sesam are nearidentical. Using a normal SE, which only includes an interface node for the connection to the wind turbine tower bottom, and including the response due to seismic displacements into the SE load file gives a match between BHawC and Sesam, and closely matches the results of the case with additional interface nodes. Doing the same but only including the dynamic response of the interface point relative to a frame of reference moving with the rigid body motions as caused by the seismic accelerations into the SE load file, significant differences occur. This is due to the lack of the loading effect of rigid body motions. The same conclusions on how these methods compare can be drawn when using different wind and wave cases. The presented results give insights into the differences between the methods and how the choice of method may influence the results.

Download Full-text

Estimation of Risk of Progressive Drifts in a Wind Farm Caused by Collision of Drift Ship

Volume 6: Ocean Space Utilization ◽

10.1115/omae2015-41473 ◽

2015 ◽

Author(s):

Eiji Hirokawa ◽

Hideyuki Suzuki ◽

Shinichiro Hirabayashi ◽

Minon Muratake

Keyword(s):

Wind Turbine ◽

Wind Farm ◽

Offshore Wind ◽

Mooring Line ◽

Offshore Wind Turbine ◽

Mooring System ◽

Environmental Load ◽

Collision Process ◽

Tank Experiment ◽

Estimation Of Risk

In off-shore wind turbine, it is difficult to determine the risk of accident caused by the mooring destruction through experiment. In this paper, the authors discuss the risk, with the case of a drifting ship wanders into the wind farm. In the design of a floating offshore wind turbine (FOWT), drift of a FOWT is considered as a serious failure mode and the mooring system must be designed to avoid the failure. The failure of mooring line is not initiated just by extreme environmental load but can be initiated by collision with a drifting ship, which enters the wind farm. This phenomenon is difficult to investigate by a tank experiment. So far, little knowledge exists about the phenomenon. In this research, a simulator to reproduce the collision process of a FOWT and a drift ship and a progressive drift of FOWTs in a wind farm was developed. Using this simulator and statistics of drift incidents of a ship, a procedure to evaluate risk of progressive drifts in a wind farm was established. In that case, second accident that a wind turbine which has started drifting caused by the drifting ship collides with one another wind turbine is expected. As a result, the risk mainly depends on the risk of drifting caused by a large displaced ship. In addition, the risk partly depends on the arrangement of wind farm.

Download Full-text

Foundation structural health monitoring of an offshore wind turbine—a full-scale case study

Structural Health Monitoring ◽

10.1177/1475921715586624 ◽

2016 ◽

Vol 15 (4) ◽

pp. 389-402 ◽

Cited By ~ 28

Author(s):

Wout Weijtjens ◽

Tim Verbelen ◽

Gert De Sitter ◽

Christof Devriendt

Keyword(s):

Structural Health Monitoring ◽

Wind Turbine ◽

Health Monitoring ◽

Full Scale ◽

Offshore Wind ◽

Offshore Wind Turbine ◽

Structural Health

Download Full-text

Feasibility study of offshore wind turbine substructures for southwest offshore wind farm project in Korea

Renewable Energy ◽

10.1016/j.renene.2014.08.039 ◽

2015 ◽

Vol 74 ◽

pp. 406-413 ◽

Cited By ~ 17

Author(s):

Wei Shi ◽

Jonghoon Han ◽

Changwan Kim ◽

Daeyong Lee ◽

Hyunkyoung Shin ◽

...

Keyword(s):

Wind Turbine ◽

Feasibility Study ◽

Wind Farm ◽

Offshore Wind ◽

Offshore Wind Turbine ◽

Offshore Wind Farm

Download Full-text

Validation of Numerical Models of the Offshore Wind Turbine From the Alpha Ventus Wind Farm Against Full-Scale Measurements Within OC5 Phase III

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.4047378 ◽

2020 ◽

Vol 143 (1) ◽

Author(s):

Wojciech Popko ◽

Amy Robertson ◽

Jason Jonkman ◽

Fabian Wendt ◽

Philipp Thomas ◽

...

Keyword(s):

Wind Speed ◽

Wind Turbine ◽

Wind Farm ◽

Operating Conditions ◽

Offshore Wind ◽

Phase Iii ◽

Offshore Wind Turbine ◽

Discrete Fourier Transforms ◽

Simulation Tools ◽

Axial Forces

Abstract The main objective of the Offshore Code Comparison Collaboration Continuation, with Correlation (OC5) project is validation of aero-hydro-servo-elastic simulation tools for offshore wind turbines (OWTs) through comparison of simulated results to the response data of physical systems. Phase III of the OC5 project validates OWT models against the measurements recorded on a Senvion 5M wind turbine supported by the OWEC Quattropod from the alpha ventus offshore wind farm. The following operating conditions of the wind turbine were chosen for the validation: (1) idling below the cut-in wind speed, (2) rotor-nacelle assembly (RNA) rotation maneuver below the cut-in wind speed, (3) power production below and above the rated wind speed, and (4) shutdown. A number of validation load cases were defined based on these operating conditions. The following measurements were used for validation: (1) strains and accelerations recorded on the support structure and (2) pitch, yaw, and azimuth angles, generator speed, and electrical power recorded from the RNA. Strains were not directly available from the majority of the OWT simulation tools; therefore, strains were calculated based on out-of-plane bending moments, axial forces, and cross-sectional properties of the structural members. The simulation results and measurements were compared in terms of time series, discrete Fourier transforms, power spectral densities, and probability density functions of strains and accelerometers. A good match was achieved between the measurements and models setup by OC5 Phase III participants.

Download Full-text

Progress on the Development of a Holistic Coupled Model of Dynamics for Offshore Wind Farms: Phase I — Aero-Hydro-Servo-Elastic Model, With Drive Train Model, for a Single Wind Turbine

Volume 10: Ocean Renewable Energy ◽

10.1115/omae2018-77886 ◽

2018 ◽

Cited By ~ 1

Author(s):

Z. Lin ◽

D. Cevasco ◽

M. Collu

Keyword(s):

Wind Turbine ◽

Failure Mode ◽

Wind Turbines ◽

Wind Farm ◽

Failure Modes ◽

Coupled Model ◽

Offshore Wind ◽

Offshore Wind Turbine ◽

Elastic Model ◽

Offshore Wind Turbines

Currently, around 1500 offshore wind turbines are operating in the UK, for a total of 5.4GW, with further 3GW under construction, and 13GW consented. Until now, the focus of the research on offshore wind turbines has been mainly on how to minimise the CAPEX, but Operation and maintenance (O&M) can represent up to 39% of the lifetime costs of an offshore wind farm, due mainly to the high cost of the assets and the harsh environment, limiting the access to these assets in a safe mode. The present work is a part of a larger project, called HOME Offshore (www.homeoffshore.org), and it has as aim an advanced interpretation of the fault mechanisms through a holistic multiphysics modelling of the wind farm. The first step (presented here) toward achieving this aim consists of two main tasks: first of all, to identify and rank the most relevant failure modes within a wind farm, identifying the component, its mode of failure, and the relative environmental conditions. Then, to assess (for each failure mode) how the full-order, nonlinear model of dynamics used to represent the dynamics of the wind turbine can be reduced in order, such that is less computationally expensive (and therefore more suitable to be scaled up to represent multiple wind turbines), but still able to capture and represent the relevant dynamics linked with the inception of the chosen failure mode. A methodology to rank the failure modes is presented, followed by an approach to reduce the order of the Aero-Hydro-Servo-Elastic (AHSE) model of dynamics adopted. The results of the proposed reduced-order models are discussed, comparing it against the full-order coupled model, and taking as case study a fixed offshore wind turbine (monopile) in gearbox failure condition.

Download Full-text