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

2014 ◽  
Vol 136 (2) ◽  
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.

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

2012 ◽  
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.

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

2010 ◽  
Author(s):  
Yoon Hyeok Bae ◽  
M. H. Kim ◽  
Young S. Shin
Keyword(s):  
Dynamic Analysis ◽  
Wind Turbines ◽  
Vertical Plane ◽  
Clean Energy ◽  
Rotor Dynamics ◽  
Offshore Wind ◽  
Irregular Waves ◽  
Dynamic Coupling ◽  
Coupled Dynamic Analysis ◽  
Floating Offshore 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.

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

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.

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

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.

Coupled Dynamic Analysis of a Tension Leg Platform Floating Offshore Wind Turbine

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Teng Wang ◽  
Hui Jin ◽  
Xiaoni Wu
Keyword(s):  
Dynamic Analysis ◽  
Wind Turbine ◽  
Offshore Wind ◽  
Wind Loads ◽  
Offshore Wind Turbine ◽  
Wave Loads ◽  
Tension Leg Platform ◽  
Floating Offshore Wind Turbine ◽  
Turbulent Wind ◽  
Coupled Dynamic Analysis

The dynamic response of a tension leg platform (TLP) floating offshore wind turbine (FOWT) was analyzed with considering the aero-hydro characteristic of the whole floating wind turbine system including the wind turbine, TLP platform, and tethers. The “aero-hydro” coupled dynamic analysis was conducted in ansys-aqwa with a dynamic link library (DLL) calculating the aerodynamics loading at every steptime based on the blade element momentum theory. Results from the coupled dynamic analysis of TLP FOWT under the condition of turbulent wind and regular wave show that the wind loads influence mainly the low-frequency response of the TLP FOWT. The wind loads have a large impact on the offsets of the TLP away from the initial position while the wave loads influence mainly the fluctuation amplitude of the TLP FOWT. The average TLP pitch response under the wind load is significantly larger due to the large wind-induced heeling moment on the wind turbine. In addition, the tension of tethers at the upwind end is greater than that at the downwind end. The wind loads could reduce effectively the average tension of the tethers, and the tension of tethers is significantly affected by the pitch motion. Results from the coupled dynamic analysis of TLP FOWT under the condition of turbulent wind and irregular wave show that the surge and pitch of TLP result in an obvious increase of thrust of the turbine and the amplitude of torque fluctuation, more attention should be paid to the pitch and surge motion of TLP FOWT.

scholarly journals Experimental and Numerical Analysis of a 10 MW Floating Offshore Wind Turbine in Regular Waves

Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2608
Author(s):  
Hyeonjeong Ahn ◽  
Hyunkyoung Shin
Keyword(s):  
Wind Turbine ◽  
Model Test ◽  
Model Tests ◽  
Offshore Wind ◽  
East Sea ◽  
Irregular Waves ◽  
Offshore Wind Turbine ◽  
Regular Waves ◽  
Floating Offshore Wind Turbine ◽  
Floating Offshore Wind Turbines

Floating offshore wind turbines (FOWTs) experience fluctuations in their platforms, owing to the various wave and wind conditions. These fluctuations not only decrease the output of the wind power generation system, but also increase the fatigue load of the structure and various equipment mounted on it. Therefore, when designing FOWTs, efficient performance with respect to waves and other external conditions must be ensured. In this study, a model test was performed with a 10 MW floating offshore wind turbine. The model test was performed by scaling down a 10 MW FOWT model that was designed with reference to a 5 MW wind turbine and a semisubmersible platform by the National Renewable Energy Laboratory and the DeepCwind project. A scale ratio of 1:90 was used for the model test. The depth of the East Sea was considered as 144 m and, to match the water depth with the geometric similarity of mooring lines, mooring tables were installed. The load cases used in the model test are combined environmental conditions, which are combined uniform wind, regular waves and uniform current. Especially, Model tests with regular waves are especially necessary, because irregular waves are superpositions of regular waves with various periods. Therefore, this study aimed to understand the characteristics of the FOWTs caused by regular waves of various periods. Furthermore, in this model test, the effect of current was investigated using the current data of the East Sea. The results obtained through the model tests were the response amplitude operator (RAO) and the effective RAO for a six degrees-of-freedom motion. The results obtained from the model tests were compared with those obtained using the numerical simulation. The purpose of this paper is to predict the response of the entire system observed in model tests through simulation.

scholarly journals Suction Bucket Pile–Soil–Structure Interactions of Offshore Wind Turbine Jacket Foundations Using Coupled Dynamic Analysis

2020 ◽  
Vol 8 (6) ◽  
pp. 416
Author(s):  
Pasin Plodpradit ◽  
Osoon Kwon ◽  
Van Nguyen Dinh ◽  
Jimmy Murphy ◽  
Ki-Du Kim
Keyword(s):  
Dynamic Analysis ◽  
Wind Turbine ◽  
Vibration Analysis ◽  
Soft Clay ◽  
Free Vibration Analysis ◽  
American Petroleum Institute ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Coupled Dynamic Analysis ◽  
Forced Vibration Analysis

This paper presents a procedure for the coupled dynamic analysis of offshore wind turbine–jacket foundation-suction bucket piles and compares the American Petroleum Institute (API) standard method and Jeanjean’s methods used to model the piles. Nonlinear springs were used to represent soil lateral, axial, and tip resistances through the P–Y, T–Z, and Q–Z curves obtained by either API’s or Jeanjean’s methods. Rotational springs with a stiffness equated to the tangent or secant modulus characterized soil resistance to acentric loads. The procedure was implemented in X-SEA program. Analyses of a laterally loaded single pile in a soft clay soil performed in both the X-SEA and Structural Analysis Computer System (SACS) programs showed good agreements. The behaviors of a five MW offshore wind turbine system in South Korea were examined by considering waves, current, wind effects, and marine growth. In a free vibration analysis done with soil stiffness through the API method, the piles were found to bend in their first mode and to twist in the second and third modes, whereas the first three modes using Jeanjean’s method were all found to twist. The natural frequencies resulting from Jeanjean’s method were higher than those from the API method. In a forced vibration analysis, the system responses were significantly influenced by soil spring stiffness type. The procedure was found to be computationally expensive due to spring nonlinearities introduced.

Numerical and Experimental Investigation Regarding the Landing Manoeuvre of a Catamaran Vessel at an Offshore Wind Turbine in Waves

2015 ◽  
Author(s):  
Daniel Ferreira González ◽  
Matthias Lemmerhirt ◽  
Moustafa Abdel-Maksoud ◽  
Marcel König ◽  
Alexander Düster
Keyword(s):  
Experimental Investigation ◽  
Time Domain ◽  
Offshore Structures ◽  
Offshore Wind ◽  
Irregular Waves ◽  
Offshore Wind Turbine ◽  
Reaction Forces ◽  
Simulation Results ◽  
The Time Domain ◽  
Hydrodynamic Effects

In this work, the landing manoeuvre of a catamaran vessel at a monopile foundation is investigated by experiments compared with numerical simulations. Therefore, a method is presented which allows simulating the described landing manoeuvre at offshore structures. The simulation in the time domain is based on potential theory using a boundary element method (BEM) and it computes the motions of the rigid body due to the hydrodynamic loads which consist of the incoming waves and the diffraction caused by the monopile. Further, a fender model is implemented, considering the reaction forces due to the friction and the deformation of the fender. The model is further able to distinguish between slip and non-slip condition of the fender. Apart from this, model tests of the landing manoeuvre were carried out with a catamaran model. During the tests the model pushed its fender against an equally scaled monopile. The motions of the vessel and the forces at the attachment of the fender were measured in regular and irregular waves. The obtained data which leads to a better understanding of the hydrodynamic effects during a landing manoeuvre is compared with the simulation results in order to improve the numerical method. The validation with experimental results shows that the method is applicable to quantify the risk of the fender suddenly slipping.

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