scholarly journals Stochastic Response Analysis for a Floating Offshore Wind Turbine Integrated with a Steel Fish Farming Cage

2018 ◽  
Vol 8 (8) ◽  
pp. 1229 ◽  
Author(s):  
Xiang Zheng ◽  
Yu Lei
Keyword(s):  
Wind Turbine ◽  
Fish Farming ◽  
Offshore Wind ◽  
Hydrodynamic Performance ◽  
Offshore Wind Turbine ◽  
Response Analysis ◽  
Stochastic Response ◽  
Floating Structure ◽  
Structural Dynamic ◽  
Floating Offshore Wind Turbine

A state-of-the-art concept integrating a deepwater floating offshore wind turbine with a steel fish-farming cage (FOWT-SFFC) is presented in this paper. The configurations of this floating structure are given in detail, showing that the multi-megawatt wind turbine sitting on the cage foundation possesses excellent hydrostatic stability. The motion response amplitude operators (RAOs) calculated by the potential-flow program WAMIT demonstrate that the hydrodynamic performance of FOWT-SFFC is much better than OC3Hywind spar and OC4DeepCwind semisubmersible wind turbines. The aero-hydro-servo-elastic modeling and time-domain simulations are carried out by FAST to investigate the dynamic response of FOWT-SFFC for several environmental conditions. The short-term extreme stochastic response reveals that the dynamic behavior of FOWT-SFFC outperforms its counterparts. From the seakeeping and structural dynamic views, it is a very competitive and promising candidate in offshore industry for both power exploitation and aquaculture in deep waters.

Dynamic Response of Spar-Type Floating Offshore Wind Turbine in Freak Wave

2019 ◽  
Author(s):  
Yougang Tang ◽  
Yan Li ◽  
Peng Xie ◽  
Xiaoqi Qu ◽  
Bin Wang
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Offshore Wind ◽  
Modulation Method ◽  
Power Coefficient ◽  
Offshore Wind Turbine ◽  
Floating Structure ◽  
Mooring Lines ◽  
Freak Wave ◽  
Floating Offshore Wind Turbine

Abstract Simulations are conducted in time domain to investigate the dynamic response of a SPAR-type floating offshore wind turbine under the scenarios with freak wave. Towards this end, a coupled aero-hydro numerical model is developed. The methodology includes a blade-element-momentum model for aerodynamics, a nonlinear model for hydrodynamics, a nonlinear restoring model of SPAR buoy, and a nonlinear algorithm for mooring cables. The OC3 Hywind SPAR-type FOWT is chosen as an example to study the dynamic response under the freak conditions, while the time series of freak wave is generated by the Random Frequency Components Selection Phase Modulation Method. The motions of platform, the tensions in the mooring lines and the power generation performance are documented in different cases. According to the simulations, it shows that the power coefficient of wind turbine decreased rapidly at the moment when freak wave acted on the floating structure.

Effects of Fish Nets on the Nonlinear Dynamic Performance of a Floating Offshore Wind Turbine Integrated with a Steel Fish Farming Cage

2020 ◽  
Vol 20 (03) ◽  
pp. 2050042 ◽  
Author(s):  
Y. Lei ◽  
S. X. Zhao ◽  
X. Y. Zheng ◽  
W. Li
Keyword(s):  
Wind Turbine ◽  
Nonlinear Dynamic ◽  
Dynamic Performance ◽  
Fish Farming ◽  
Ocean Waves ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Offshore Wind Turbine ◽  
Wind Sea

This paper aims to study the effects of fish nets on the nonlinear dynamic performance of a floating offshore wind turbine integrated with a steel fish farming cage (FOWT-SFFC). Fully coupled aero-hydro-servo-elastic numerical models of FOWT-SFFC, with and without nets, are constructed to probe the nonlinear time-domain stochastic response. The first-order potential flow model with quadratic drag forces is employed to calculate the hydrodynamic loading on the foundation. The effects of nets on the damping ratios of 6 degree-of-freedom motions and on their displacement response amplitude operators (RAOs) are respectively investigated in numerical decay tests and monochromatic regular waves. The results show that the nets help to increase the damping level for the whole system and reduce motion RAOs when wave periods are around the natural periods of motions, while nets play insignificant role in motions when wave periods are far away from motion natural periods. The dynamic performances of FOWT-SFFC with and without nets under random ocean waves, the combined random wind and random waves as well as current are comprehensively compared and discussed. The simulation results indicate that in wind-sea dominated conditions, the nets tend to slightly increase the dynamic responses of FOWT-SFFC, especially the components corresponding to natural periods. Nonetheless, under sea states that comprise both wind-sea waves and swell, nets help to reduce the dynamic responses of FOWT-SFFC by introducing additional damping.

A Novel Structural Form of Semi-Submersible Platform for a Floating Offshore Wind Turbine with Hydrodynamic Performance Analysis

2013 ◽  
Vol 477-478 ◽  
pp. 109-113
Author(s):  
Bin Bin Lai ◽  
Cheng Bi Zhao ◽  
Xiao Ming Chen ◽  
You Hong Tang ◽  
Wei Lin
Keyword(s):  
Wind Turbine ◽  
Wind Farm ◽  
Wind Waves ◽  
Simulation Method ◽  
Offshore Wind ◽  
Hydrodynamic Performance ◽  
Offshore Wind Turbine ◽  
Structural Form ◽  
Floating Platform ◽  
Floating Offshore Wind Turbine

With the mature of floating offshore wind turbine technology, floating wind farm building in the deep sea becomes an inevitable trend. In the design of floating offshore wind turbine, the change of structural form is the main factor influencing hydrodynamic performance. This research, taking a typical sea condition in China's coastal areas as the object of study, designs a novel semi-submersible foundation for NREL 5 MW offshore wind turbine in 200 m deep water. In the design, deep-draft buoys structures are used to reduce the force of waves on the floating offshore, while damping structures are used to optimize the stability of wind turbine and reduce the heave amplitude. By means of numerical simulation method, the hydrodynamic performance of semi-submersible support is studied. Meanwhile, the response amplitude operators (RAOs) and the wave response motions of platform are calculated. The results in time domain indicate that the floating wind turbine system can keep safe and survive in the harsh sea condition, coupling wind, waves and currents. It is showed that the designed semi-submersible support of platform has excellent hydrodynamic performance. This change of structural form may serve as a reference on the development of offshore wind floating platform.

scholarly journals On Motion and Hydroelastic Analysis of a Floating Offshore Wind Turbine

2019 ◽  
Author(s):  
Azin Lamei ◽  
Masoud Hayatdavoodi ◽  
Carlos Wong ◽  
Bin Tang
Keyword(s):  
Wind Turbine ◽  
Offshore Wind ◽  
Elastic Response ◽  
Offshore Wind Turbine ◽  
The Novel ◽  
Floating Structure ◽  
Hydrodynamic Loads ◽  
Flexible Bodies ◽  
Floating Offshore Wind Turbine ◽  
Environmental Loads

Abstract This study is concerned with motion analysis and hydroelastic response of a floating offshore wind turbine to wave loads. The novel floating structure, made of prestressed concrete, is designed to support multiple wind turbines, and it rotates according to the environmental loads to face the incoming wind. The floating structure is attached to a mooring line that allows the rotation of the structure in response to the environmental loads. The floating structure is an equilateral triangular platform. The wind turbines are located at the vertices. Due to the dimensional characteristics of the structure, elasticity of the floating platform plays an important role in its dynamics. While the dynamic response of the structure is driven by both aerodynamic and hydrodynamic loads, this study focuses on the motion and elastic response of the novel floating structure to the hydrodynamic loads only. The three dimensional hydrodynamic loads on the floating structure are obtained by use of the constant panel approach of the Green function method, subject to linear mooring loads. A finite element analysis is carried out for the calculation of the elastic response of the structure. Computations of the integrated linear structure-fluid-structure interaction problem are performed in frequency domain using HYDRAN, a computer program written for the linear dynamic analysis of rigid and flexible bodies. Results presented here include the response amplitude operators of both the rigid and flexible bodies to incoming waves of various frequencies and directions. Also presented are the wave-induced stresses on the floating body, and the elastic deformations.

Dynamic Response Analysis of a Floating Offshore Wind Turbine During Severe Typhoon Event

2013 ◽  
Author(s):  
Tomoaki Utsunomiya ◽  
Iku Sato ◽  
Shigeo Yoshida ◽  
Hiroshi Ookubo ◽  
Shigesuke Ishida
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Response Analysis ◽  
Dynamic Response Analysis ◽  
Floating Offshore Wind Turbine ◽  
Demonstration Experiment ◽  
Typhoon Event

In this paper, dynamic response analysis of a Floating Offshore Wind Turbine (FOWT) with Spar-type floating foundation is presented. The FOWT mounts a 100kW down-wind turbine, and is grid-connected. It was launched at sea on 9th June 2012, and moored on 11th for the purpose of the demonstration experiment. During the experiment, the FOWT was attacked by severe typhoon events twice. Among them, Sanba (international designation: 1216) was the strongest tropical cyclone worldwide in 2012. The central atmospheric pressure was 940 hPa when it was close to the FOWT, and the maximum significant wave height of 9.5m was recorded at the site. In this paper, the dynamic responses of the platform motion, the stresses at the tower sections and the chain tensions during the typhoon event, Sanba (1216), have been analyzed, and compared with the measured data. Through the comparison, validation of the numerical simulation tool (Adams with SparDyn developed by the authors) has been made.

Validation of the Motion Analysis Method of Floating Offshore Wind Turbines Using Observation Data Acquired by Full Scale Demonstration Project

2019 ◽  
Author(s):  
Haruki Yoshimoto ◽  
Ken Kamizawa
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Demonstration Project ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Analysis Method ◽  
Floating Structure ◽  
Floating Offshore Wind Turbine ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

Abstract In recent years, the social demands for the introduction of renewable energy are increasing, demonstration projects of floating offshore wind turbine are being implemented and planned around the world. In Japan, a demonstration test named Fukushima FORWARD (Fukushima Floating Offshore Wind Farm Demonstration Project) has been conducted since 2011. Fukushima FORWARD is a project carried out by the Ministry of Economy, Trade and Industry, the world’s first floating offshore windfarm with a total capacity of 14 MW, including three floating offshore wind facilities and one floating offshore substation. In Fukushima FORWARD, Japan Marine United Corporation is in charge of floater part EPCI (Engineering, Procurement, Construction and Installation) of one floating offshore wind facility and one floating offshore substation. The floating offshore wind turbine (Ship Name: Fukushima Hamakaze) designed and built by Japan Marine United Corporation is equipped with a downwind 5 MW wind turbine. The floating structure adopts the advanced spar shape in order to reduce wave frequency motions and is moored by six spread catenary mooring lines. In the design of floating offshore wind turbines, it is important to estimate motions with high accuracy. Especially floating offshore wind turbine equipped with horizontal axis wind turbine requires heavy RNA (Rotor Nacelle Assembly) to be installed on the tower, and the floater motion greatly influences the design of the tower base. The tower base is required to have sufficient reliability because it directly leads to collapse of the wind turbine if it is damaged. On the other hand, the tower base is generally constructed with a cylinder made of extremely thick steel plate which is difficult to bend and weld, and if it has excessive safety factor the cost has increased greatly. Also, estimating the motion is the basis for estimating the load on the floating structure. In this paper, statistical analysis of long-term data measured by Fukushima FORWARD floating offshore wind turbine focusing on the motion and its features are introduced. In addition, we compare the motion obtained by potential theory and coupled analysis with actually measured motion using the measured wave and wind data and evaluate the validity of the analysis method.

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