scholarly journals Fatigue Strength Assessment of Semi-Submersible Floating Wind Turbine Foundation under Turbulent Wind

2018 ◽  
Vol 7 (1) ◽  
pp. 27
Author(s):  
Song SANG ◽  
Zhaofei CHU ◽  
Aixia CAO ◽  
Zixin DONG ◽  
Jinqi DONG
Keyword(s):  
Wind Turbine ◽  
Fatigue Damage ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Connecting Rod ◽  
Strength Assessment ◽  
Structural Fatigue ◽  
Floating Wind Turbine ◽  
Fast Wind ◽  
Turbine Model

Under the complex marine environment load and the role of the upper wind turbine load, deep sea floating wind turbine support structure would suffer fatigue damage, which often endangers the safety of the wind turbine system. This paper chose the "5 MW baseline" wind turbine model which published by the US National Renewable Energy Laboratory (NREL) as the design basis. The paper uses the OC4-DeepC wind semi-submersible offshore wind turbine model for the verification of offshore floating wind turbines. According to the characteristics of stress and the distribution of stress, the paper selects seven key parts which are prone to fatigue damage are screened, respectively established local finite element models and carried out grid encryption. Based on the SESAM hydrodynamic analysis software and FAST wind motor dynamic load calculation procedure, the fatigue damage of the target node under the action of wind turbine load is studied. The results show that the structural fatigue damage occurs mainly at the horizontal connection of the upper part of the neutral column and the diagonal connection of the lower part of the neutral column. The fatigue damage degree of the crown and the saddle point is relatively large at the connecting rod position.

Key Contributors to Lifetime Accumulated Fatigue Damage in an Offshore Wind Turbine Support Structure

2017 ◽  
Author(s):  
Emil Smilden ◽  
Erin E. Bachynski ◽  
Asgeir J. Sørensen
Keyword(s):  
Wind Turbine ◽  
Fatigue Damage ◽  
Control Strategies ◽  
Time Domain Analysis ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wave Loads ◽  
Support Structure ◽  
Wear And Tear ◽  
Collateral Effects

A simulation study is performed to identify the key contributors to lifetime accumulated fatigue damage in the support-structure of a 10 MW offshore wind turbine placed on a monopile foundation in 30 m water depth. The relative contributions to fatigue damage from wind loads, wave loads, and wind/wave misalignment are investigated through time-domain analysis combined with long-term variations in environmental conditions. Results show that wave loads are the dominating cause of fatigue damage in the support structure, and that environmental condtions associated with misalignment angle > 45° are insignificant with regard to the lifetime accumulated fatigue damage. Further, the results are used to investigate the potential of event-based use of control strategies developed to reduce fatigue loads through active load mitigation. Investigations show that a large reduction in lifetime accumulated fatigue damage is possible, enabling load mitigation only in certain situations, thus limiting collateral effects such as increased power fluctuations, and wear and tear of pitch actuators and drive-train components.

The Current Situation and Recent Advances of Deep-Water Floating Wind Turbine

2012 ◽  
Vol 226-228 ◽  
pp. 772-775
Author(s):  
Yu Chen ◽  
Chun Li ◽  
Wei Gao ◽  
Jia Bin Nie
Keyword(s):  
Wind Turbine ◽  
Deep Water ◽  
Rapid Development ◽  
Coupled Model ◽  
Wind Farms ◽  
International Standards ◽  
Offshore Wind ◽  
Current Status ◽  
Offshore Wind Turbine ◽  
Floating Wind Turbine

Offshore wind turbine is a novel approach in the field of wind energy technology. With the rapid development of coastal wind farms, it is the trend to move them outward to deep-water district. However, the cost of construction rises significantly with the increase in water depth. Floating wind turbine is one of the efficient methods to solve this problem. The early history, current status and cutting-edge improvements of overseas offshore floating wind turbine as well as the shortcomings shall be presented. The concept designs, international standards, fully coupled model simulations and hydrodynamic experiments will be illustrated and discussed together with the development of the theory and the related software modules. Thus a novel researching method and concept shall be presented to provide reference for future researches

scholarly journals Mooring Line Damping Estimation for a Floating Wind Turbine

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Dongsheng Qiao ◽  
Jinping Ou
Keyword(s):  
Wind Turbine ◽  
Estimation Method ◽  
Excitation Amplitude ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Scale Model ◽  
Mooring Line ◽  
Offshore Wind Turbine ◽  
Floating Wind Turbine ◽  
Excitation Period

The dynamic responses of mooring line serve important functions in the station keeping of a floating wind turbine (FWT). Mooring line damping significantly influences the global motions of a FWT. This study investigates the estimation of mooring line damping on the basis of the National Renewable Energy Laboratory 5 MW offshore wind turbine model that is mounted on the ITI Energy barge. A numerical estimation method is derived from the energy absorption of a mooring line resulting from FWT motion. The method is validated by performing a 1/80 scale model test. Different parameter changes are analyzed for mooring line damping induced by horizontal and vertical motions. These parameters include excitation amplitude, excitation period, and drag coefficient. Results suggest that mooring line damping must be carefully considered in the FWT design.

Strength Assessment of Jacket Offshore Wind Turbine Support Structure Accounting for Rupture1

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Baran Yeter ◽  
Yordan Garbatov ◽  
C. Guedes Soares
Keyword(s):  
Wind Turbine ◽  
Low Cycle Fatigue ◽  
High Stress ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Small Scale ◽  
Support Structures ◽  
Support Structure ◽  
Strength Assessment ◽  
High Stress Concentration

The objective of the present work is to carry out the strength assessment of jacket offshore wind turbine support structures subjected to progressive rupture. A defect existing in a structure made during the fabrication may turn into a small-scale rupture and because of the high-stress concentration and low-cycle fatigue load. Therefore, the ultimate load-carrying capacity of the support structure is analyzed accounting for the progress of the rupture until the leg component experiences a full rupture along its circumference. The effect of imperfection severity is also investigated. The moment–curvature relationship of the structure concerning the studied cases is presented. Furthermore, the jacket support structures, at different water depths, are also analyzed and discussed. Finally, some of the leg components are removed one by one to study the redundancy of the jacket support structure at 80-m water depth.

Simulation of an Offshore Wind Turbine Using a Weakly-Compressible CFD Solver Coupled With a Blade Element Turbine Model

2019 ◽  
Author(s):  
Baptiste Elie ◽  
Guillaume Oger ◽  
David Le Touzé
Keyword(s):  
Wind Turbine ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Simulation Tool ◽  
Weakly Compressible ◽  
Element Simulation ◽  
Development And Validation ◽  
Elastic Modules ◽  
Turbine Model ◽  
Blade Element

Abstract The present study addresses the first steps of development and validation of a coupled CFD-BE (Blade Element) simulation tool dedicated to offshore wind turbine farm modelling. The CFD part is performed using a weakly-compressible solver (WCCH). The turbine is taken into account using FAST (from NREL) and its effects are imposed into the fluid domain through an actuator line model. The first part of this paper is dedicated to the presentation of the WCCH solver and its coupling with the aero-elastic modules from FAST. In a second part, for validation purposes, comparisons between FAST and the WCCH-FAST coupling are presented and discussed. Finally, a discussion on the performances, advantages and limitations of the formulation proposed is provided.

Parametric Study of Catenary Mooring System for a Semisubmersible Floating Wind Turbine in Intermediate Water Depth

2020 ◽  
Author(s):  
Jiawen Li ◽  
Qiang Zhang ◽  
Jiali Du ◽  
Yichen Jiang
Keyword(s):  
Wind Turbine ◽  
Water Depth ◽  
Offshore Wind ◽  
Design Parameters ◽  
Mooring Line ◽  
Offshore Wind Turbine ◽  
Reference Structure ◽  
Intermediate Water ◽  
Mooring System ◽  
Floating Wind Turbine

Abstract This paper presents a parametric design study of the mooring system for a floating offshore wind turbine. We selected the OC4 DeepCwind semisubmersible floating wind turbine as the reference structure. The design water depth was 50 m, which was the transition area between the shallow and deep waters. For the floating wind turbine working in this water area, the restoring forces and moments provided by the mooring lines were significantly affected by the heave motion amplitude of the platform. Thus, the mooring design for the wind turbine in this working depth was different from the deep-water catenary mooring system. In this study, the chosen design parameters were declination angle, fairlead position, mooring line length, environmental load direction, and mooring line number. We conducted fully coupled aero-hydro dynamic simulations of the floating wind turbine system in the time domain to investigate the influences of different mooring configurations on the platform motion and the mooring tension. We evaluated both survival and accidental conditions to analyze the mooring safety under typhoon and mooring fail conditions. On the basis of the simulation results, this study made several design recommendations for the mooring configuration for floating wind turbines in intermediate water depth applied in China.

scholarly journals Study of Floating Wind Turbine with Modified Tension Leg Platform Placed in Regular Waves

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 703 ◽  
Author(s):  
Juhun Song ◽  
Hee-Chang Lim
Keyword(s):  
Wind Turbine ◽  
Real Data ◽  
Offshore Wind ◽  
Scale Model ◽  
Offshore Wind Turbine ◽  
Wave Loads ◽  
Tension Leg Platform ◽  
Mooring Lines ◽  
Floating Wind Turbine ◽  
Wave Conditions

In this study, the typical ocean environment was simulated with the aim to investigate the dynamic response under various environmental conditions of a Tension Leg Platform (TLP) type floating offshore wind turbine system. By applying Froude scaling, a scale model with a scale of 1:200 was designed and model experiments were carried out in a lab-scale wave flume that generated regular periodic waves by means of a piston-type wave generator while a wave absorber dissipated wave energy on the other side of the channel. The model was designed and manufactured based on the standard prototype of the National Renewable Energy Laboratory (NREL) 5 MW offshore wind turbine. In the first half of the study, the motion and structural responses for operational wave conditions of the North Sea near Scotland were considered to investigate the performance of a traditional TLP floating wind turbine compared with that of a newly designed TLP with added mooring lines. The new mooring lines were attached with the objective of increasing the horizontal stiffness of the system and thereby reducing the dominant motion of the TLP platform (i.e., the surge motion). The results of surge translational motions were obtained both in the frequency domain, using the response amplitude operator (RAO), and in the time domain, using the omega arithmetic method for the relative velocity. The results obtained show that our suggested concept improves the stability of the platform and reduces the overall motion of the system in all degrees-of-freedom. Moreover, the modified design was verified to enable operation in extreme wave conditions based on real data for a 100-year return period of the Northern Sea of California. The loads applied by the waves on the structure were also measured experimentally using modified Morison equation—the formula most frequently used to estimate wave-induced forces on offshore floating structures. The corresponding results obtained show that the wave loads applied on the new design TLP had less amplitude than the initial model and confirmed the significant contribution of the mooring lines in improving the performance of the system.

VolturnUS 1:8: Conclusion of 18-Months of Operation of the First Grid-Connected Floating Wind Turbine Prototype in the Americas

2015 ◽  
Author(s):  
Anthony M. Viselli ◽  
Andrew J. Goupee ◽  
Habib J. Dagher ◽  
Christopher K. Allen
Keyword(s):  
Wind Turbine ◽  
Large Data ◽  
Full Scale ◽  
Offshore Wind ◽  
Mooring Line ◽  
Offshore Wind Turbine ◽  
Data Set ◽  
Floating Offshore Wind Turbine ◽  
The Past ◽  
Floating Wind Turbine

This paper presents an overview of the successful conclusion of 18 months of testing the first grid-connected floating offshore wind turbine prototype in the Americas. The prototype, called VolturnUS 1:8, was installed off Castine, Maine, USA. The prototype is a 1:8 scale prototype and serves to de-risk the deployment of a full-scale 6MW turbine. VolturnUS utilizes innovations in materials, construction, and deployment technologies such as a concrete semi-submersible hull and an advanced composite tower to reduce the costs of offshore wind. The prototype unit was designed following the American Bureau of Shipping (ABS) “Guide for Building and Classing Floating Offshore Wind Turbine Installations”. Froude scaling was used in designing the 1:8-scale VolturnUS prototype so that the motions of the prototype in the relatively protected site represent those of the full-scale unit in an open site farther offshore. During the past year, a comprehensive instrumentation package monitored key performance characteristics of the platform during operational, extreme, and survival storm conditions. Data collected include: wind speed, turbine power, rotor angular frequency, blade pitch, torque, acceleration; tower bending moment, 6 DOF accelerations at tower top and base, mooring line tensions, and wave elevation at the platform. During the past year the prototype has experienced many environments representative of scaled ABS design conditions including operational wind and sea-states, 50-year sea states and 500-year survival sea states. This large data set provides a unique view of a near full-scale floating wind turbine subjected to its prescribed environmental conditions. Inspections of the concrete hull following removal provided confirmation of material durability. Marine growth measurements provide data for future design efforts.

scholarly journals Large Aeroelastic Model of a Floating Offshore Wind Turbine: Mechanical and Mechatronics Design

2019 ◽  
Author(s):  
Sara Muggiasca ◽  
Alessandro Fontanella ◽  
Federico Taruffi ◽  
Hermes Giberti ◽  
Alan Facchinetti ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Large Scale ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Ocean Engineering ◽  
Floating Structure ◽  
Aeroelastic Model ◽  
Blue Growth ◽  
Turbine Model ◽  
The Eu

Abstract This paper deals with the mechatronic design of a large-scale wind turbine model (outdoor scaled prototype) based on the DTU 10MW. This is going to be integrated in the model of a multi-purpose floating structure to be deployed at the Natural Ocean Engineering Laboratory (NOEL) in Reggio Calabria (Italy). The floating wind turbine model is the downscaling of the full-scale structure designed within the EU H2020 Blue Growth Farm project. The structural design of the scaled wind turbine is presented, starting from the aeroelastic and aerodynamic design carried out in a previous work.

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