Rotor-Floater-Mooring Coupled Dynamic Analysis of Mini TLP-Type Offshore Floating Wind Turbines

An increasing number of floating offshore wind turbines are planned and designed these days due to their vast potential in massive generation of clean energy from ocean wind. In the present study, a numerical prediction tool has been developed for the fully coupled dynamic analysis of an offshore floating wind turbine system in time domain including blade-rotor dynamics and control, mooring dynamics, and platform motions. In the new computer program, the dynamic coupling between the rotating blades and the floater is considered in addition to the mooring-floater dynamic coupling so that the influence of rotor dynamics on the hull-mooring performance and vice versa can be assessed. Mono-column mini TLPs with 1.5MW units for two different water depths, 80m and 200m, are selected as an example. The TLP becomes stiffer both in horizontal- and vertical-plane modes as water depth decreases. As a result, wave-frequency motions and the resulting tendon tensions tend to increase in the 80-m case. However, the coupling effects with rotors are decreased in the shallower depth case. When compared with the uncoupled analysis, we can observe more pronounced rotor-dynamics effects at high frequencies in the coupled simulations, which may appreciably influence fatigue life in the case of larger blades. The developed technology and numerical tool are readily applicable to the design of new offshore floating wind farms in irregular waves, dynamic winds, and steady currents.

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Aero-Elastic-Floater-Mooring Coupled Dynamic Analysis of FOWT (Floating Offshore Wind Turbine) in Maximum Operation and Survival Conditions

Volume 4: Offshore Geotechnics; Ronald W. Yeung Honoring Symposium on Offshore and Ship Hydrodynamics ◽

10.1115/omae2012-83545 ◽

2012 ◽

Cited By ~ 1

Author(s):

Y. H. Bae ◽

M. H. Kim ◽

Q. Yu ◽

J. K. Heo

Keyword(s):

Dynamic Analysis ◽

Wind Turbine ◽

Clean Energy ◽

Offshore Wind ◽

Irregular Waves ◽

Offshore Wind Turbine ◽

Coupled Dynamic Analysis ◽

Floating Offshore Wind Turbines ◽

Mooring Dynamics ◽

Dynamics And Control

Increasing numbers of FOWTs (floating offshore wind turbines) are planned in the coming years due to their high potential in massive generation of clean energy from ocean-wind. In the present study, a numerical prediction tool has been developed for the fully coupled dynamic analysis of an FOWT system in time domain including aero-loading, blade-rotor dynamics and control, mooring dynamics, and platform motions so that the influence of rotor-control dynamics on the hull-mooring performance and vice versa can be assessed. Hywind spar design with 5MW turbine is selected as an example, and two different environmental conditions, maximum operational and survival conditions, are applied for this study. The maximum operational condition means the maximum environmental condition that wind turbine can work normally, and the survival condition represents the extreme situation without any blade-turbine operation. Through this study, it is seen that the design environments for different structural components of FOWT can be different. The developed technology and numerical tool are readily applicable to the design of any future FOWTs in any combinations of irregular waves, dynamic winds, and steady currents.

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Aero-Elastic-Control-Floater-Mooring Coupled Dynamic Analysis of Floating Offshore Wind Turbine in Maximum Operation and Survival Conditions

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.4025029 ◽

2014 ◽

Vol 136 (2) ◽

Cited By ~ 7

Author(s):

Y. H. Bae ◽

M. H. Kim

Keyword(s):

Dynamic Analysis ◽

Clean Energy ◽

Offshore Wind ◽

Irregular Waves ◽

Offshore Wind Turbine ◽

Coupled Dynamic Analysis ◽

Floating Offshore Wind Turbines ◽

Mooring Dynamics ◽

Dynamics And Control ◽

The Time Domain

Increasing numbers of floating offshore wind turbines (FOWTs) are planned in the coming years due to their high potential in the massive generation of clean energy from ocean wind. In the present study, a numerical prediction tool has been developed for the fully coupled dynamic analysis of an FOWT system in the time domain including aero-loading, tower/blade elasticity, blade-rotor dynamics and control, mooring dynamics, and platform motions so that the influence of aero-elastic-control dynamics on the hull-mooring performance and vice versa can be assessed. The Hywind spar design with a 5 MW National Renewable Energy Laboratory (NREL) turbine is selected as an example and two different collinear wind-wave-current environmental conditions, maximum operational and survival conditions, are applied for this study. The maximum operational condition means the maximum environmental condition with normal blade-turbine operation and the survival condition represents the extreme situation without any blade-turbine operation. Through this study, it is seen that the ultimate-loading environments for different structural components of the FOWT can be different. The developed technology and numerical tool are readily applicable to the design of any type of future FOWTs in any combinations of irregular waves, dynamic winds, and steady currents.

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Coupled Dynamic Analysis for Multi-Unit Floating Offshore Wind Turbine in Maximum Operational and Survival Conditions

Volume 9: Ocean Renewable Energy ◽

10.1115/omae2015-42062 ◽

2015 ◽

Author(s):

H. K. Jang ◽

H. C. Kim ◽

M. H. Kim ◽

K. H. Kim

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Time Domain ◽

Offshore Wind ◽

Offshore Wind Turbine ◽

Random Waves ◽

Mooring Lines ◽

Floating Offshore Wind Turbine ◽

Coupled Dynamic Analysis ◽

Floating Offshore Wind Turbines

Numerical tools for a single floating offshore wind turbine (FOWT) have been developed by a number of researchers, while the investigation of multi-unit floating offshore wind turbines (MUFOWT) has rarely been performed. Recently, a numerical simulator was developed by TAMU to analyze the coupled dynamics of MUFOWT including multi-rotor-floater-mooring coupled effects. In the present study, the behavior of MUFOWT in time domain is described through the comparison of two load cases in maximum operational and survival conditions. A semi-submersible floater with four 2MW wind turbines, moored by eight mooring lines is selected as an example. The combination of irregular random waves, steady currents and dynamic turbulent winds are applied as environmental loads. As a result, the global motion and kinetic responses of the system are assessed in time domain. Kane’s dynamic theory is employed to formulate the global coupled dynamic equation of the whole system. The coupling terms are carefully considered to address the interactions among multiple turbines. This newly developed tool will be helpful in the future to evaluate the performance of MUFOWT under diverse environmental scenarios. In the present study, the aerodynamic interactions among multiple turbines including wake/array effect are not considered due to the complexity and uncertainty.

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Proposal and Performance Study of a Novel Mooring System with Six Mooring Lines for Spar-Type Offshore Wind Turbines

Applied Sciences ◽

10.3390/app112411665 ◽

2021 ◽

Vol 11 (24) ◽

pp. 11665

Author(s):

Shi Liu ◽

Yi Yang ◽

Chao Wang ◽

Yuangang Tu

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Offshore Wind ◽

Irregular Waves ◽

Offshore Wind Turbine ◽

Mooring System ◽

Mooring Lines ◽

Included Angle ◽

Offshore Wind Turbines ◽

Floating Offshore Wind Turbines

Spar-type floating offshore wind turbines commonly vibrate excessively when under the coupling impact of wind and wave. The wind turbine vibration can be controlled by developing its mooring system. Thus, this study proposes a novel mooring system for the spar-type floating offshore wind turbine. The proposed mooring system has six mooring lines, which are divided into three groups, with two mooring lines in the same group being connected to the same fairlead. Subsequently, the effects of the included angle between the two mooring lines on the mooring-system’s performance are investigated. Then, these six mooring lines are connected to six independent fairleads for comparison. FAST is utilized to calculate wind turbine dynamic response. Wind turbine surge, pitch, and yaw movements are presented and analyzed in time and frequency domains to quantitatively evaluate the performances of the proposed mooring systems. Compared with the mooring system with six fairleads, the mooring system with three fairleads performed better. When the included angle was 40°, surge, pitch, and yaw movement amplitudes of the wind turbine reduced by 39.51%, 6.8%, and 12.34%, respectively, when under regular waves; they reduced by 56.08%, 25.00%, and 47.5%, respectively, when under irregular waves. Thus, the mooring system with three fairleads and 40° included angle is recommended.

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Dynamic Analysis of Mooring Cables with Application to Floating Offshore Wind Turbines

Journal of Engineering Mechanics ◽

10.1061/(asce)em.1943-7889.0000999 ◽

2016 ◽

Vol 142 (3) ◽

pp. 04015101 ◽

Cited By ~ 1

Author(s):

Crescenzo Petrone ◽

Nicholas D. Oliveto ◽

Mettupalayam V. Sivaselvan

Keyword(s):

Dynamic Analysis ◽

Wind Turbines ◽

Offshore Wind ◽

Offshore Wind Turbines ◽

Floating Offshore Wind Turbines

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On the Modeling of Spar-Type Floating Offshore Wind Turbines

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.569-570.636 ◽

2013 ◽

Vol 569-570 ◽

pp. 636-643 ◽

Cited By ~ 8

Author(s):

Van Nguyen Dinh ◽

Biswajit Basu

Keyword(s):

Wind Turbines ◽

Operating Conditions ◽

Offshore Wind ◽

Wave Loads ◽

Dynamic Coupling ◽

Modeling Tools ◽

Modeling And Analysis ◽

Offshore Wind Turbines ◽

Floating Offshore Wind Turbines ◽

Floating Platforms

In this paper an overview about floating offshore wind turbines (FOWT) including operating conditions, property and applicability of the barge, tension-leg, and spar floating platforms is described. The spar-floating offshore wind turbines (S-FOWT) have advantages in deepwater and their preliminary design, numerical modeling tools and integrated modeling are reviewed. Important conclusions about the nacelle and blade motions, tower response, effects of wind and wave loads, overall vibration and power production of the S-FOWT are summarized. Computationally-simplified models with acceptable accuracy are necessary for feasibility and pre-engineering studies of the FOWT. The design needs modeling and analysis of aero-hydro-servo dynamic coupling of the entire FOWT. This paper also familiarizes authors with FOWT and its configurations and modeling approaches.

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Study of motion of spar-type floating wind turbines in waves with effect of gyro moment at inclination

Journal of Naval Architecture and Marine Engineering ◽

10.3329/jname.v9i1.10732 ◽

2012 ◽

Vol 9 (1) ◽

pp. 67-79 ◽

Cited By ~ 8

Author(s):

N. Mostafa ◽

M. Murai ◽

R. Nishimura ◽

O. Fujita ◽

Y. Nihei

Keyword(s):

Wind Turbines ◽

Offshore Structures ◽

Moment Of Inertia ◽

Offshore Wind ◽

Irregular Waves ◽

Scale Model ◽

Water Tank ◽

Offshore Wind Turbines ◽

Floating Offshore Wind Turbines ◽

Marine Engineering

Recently, a number of research groups have paid much attention to the study of Floating Offshore Wind Turbines (FOWTs). Similar to other offshore structures, the FOWTs are subjected to irregular waves and wind loads which cause a dynamic response in the structures. Under marine environmental conditions, they face many forces which prevent them from floating in the upright condition; they incline as a result of the winds, strong currents, typhoons, cyclones, storms etc. The motion of the FOWT might be changed by a change in gyroscopic effect which depends on the angular velocity and moment of inertia of the blade. Therefore, to investigate the effect of the gyro moment on the motion of the FOWT, two types of experiment were carried out in a water tank using a 1/360 scale model of a prototype FOWT. Firstly, the interaction between the rotary motion of the wind turbine blade and the dynamic motion of the SPAR-type FOWT was studied at small angles of inclination in regular waves. Secondly, the interaction between the change of rotational speed as well as moment of inertia of the blade and the motion of the FOWT was studied. In this paper, numerical calculations have been carried out using potential theory based on the 3D panel method. Finally, the experimental results are compared with the results of numerical simulation and findings are discussed. DOI: http://dx.doi.org/10.3329/jname.v9i1.10732 Journal of Naval Architecture and Marine Engineering 9(2012) 67-79

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Integrated Dynamic Analysis of Floating Offshore Wind Turbines

Volume 1: Offshore Technology; Offshore Wind Energy; Ocean Research Technology; LNG Specialty Symposium ◽

10.1115/omae2006-92291 ◽

2006 ◽

Cited By ~ 81

Author(s):

Finn Gunnar Nielsen ◽

Tor David Hanson ◽

Bjo̸rn Skaare

Keyword(s):

Wind Speed ◽

Dynamic Analysis ◽

Wind Turbines ◽

Control Strategy ◽

Rotor Blade ◽

Offshore Wind ◽

Offshore Wind Turbines ◽

Pitch Control ◽

Floating Offshore Wind Turbines ◽

Wind Velocities

Two different simulation models for integrated dynamic analysis of floating offshore wind turbines are described and compared with model scale experiments for the Hywind concept for floating offshore wind turbines. A variety of both environmental conditions and wind turbine control schemes are tested. A maximum power control strategy is applied for wind velocities below the rated wind speed for the wind turbine, while a constant power control strategy is achieved by controlling the rotor blade pitch for wind velocities above rated wind speed. Conventional rotor blade pitch control for wind velocities above rated wind speed introduces negative damping of the tower motion. This results in excitation of the natural frequency in pitch for the tower and may lead to unacceptable tower motions. Active damping of the undesirable tower motions is obtained by an additional pitch control algorithm based on measurement of the tower velocity.

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