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.

Dynamic Modeling and Simulation of a Spar Floating Offshore Wind Turbine With Consideration of the Rotor Speed Variations

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Mohammed Khair Al-Solihat ◽  
Meyer Nahon ◽  
Kamran Behdinan
Keyword(s):  
System Dynamics ◽  
Wind Turbine ◽  
Torque Control ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Aerodynamic Load ◽  
Floating Platform ◽  
Dynamic Simulations ◽  
Floating Offshore Wind Turbine ◽  
Wind Turbine Tower

This paper presents a rigid multibody dynamic model to simulate the dynamic response of a spar floating offshore wind turbine (FOWT). The system consists of a spar floating platform, the moorings, the wind turbine tower, nacelle, and the rotor. The spar platform is modeled as a six degrees-of-freedom (6DOFs) rigid body subject to buoyancy, hydrodynamic and moorings loads. The wind turbine tower supports rigid nacelle and rotor at the tip. The rigid rotor is modeled as a disk spinning around its axis and subject to the aerodynamic load. The generator torque control law is incorporated into the system dynamics to capture the rotor spinning speed response when the turbine is operating below the rated wind speed. The equations of motions are derived using Lagrange's equation in terms of the platform quasi-coordinates and rotor spin speed. The external loads due to hydrostatics, hydrodynamics, and aerodynamics are formulated and incorporated into the equations of motion. The dynamic simulations of the spar FOWT are performed for three load cases to examine the system eigen frequencies, free decay response, and response to a combined wave and wind load. The results obtained from the present model are validated against their counterparts obtained from other simulation tools, namely, FAST, HAWC2, and Bladed, with excellent agreement. Finally, the influence of the rotor gyroscopic moment on the system dynamics is investigated.

Structural Control of an Ultra-Large Semi-Submersible Floating Offshore Wind Turbine

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Zhixin Zhao ◽  
Wenhua Wang ◽  
Dongdong Han ◽  
Wei Shi ◽  
Yulin Si ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Dynamic Model ◽  
Structural Control ◽  
Degrees Of Freedom ◽  
Vibration Suppression ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Platform ◽  
Floating Offshore Wind Turbine ◽  
Proposed Model

Abstract A braceless semi-submersible floating platform is proposed for a Technical University of Denmark (DTU) 10-MW wind turbine at moderate water depths with reference to an existing National Renewable Energy Laboratory (NREL) 5-MW braceless semi-submersible floating platform, and a servo control system for a 10-MW semi-submersible floating offshore wind turbine (FOWT) is introduced. To control the ultimate and fatigue loads of the FOWT, a fore-aft tuned mass damper (TMD) installed in the nacelle of the 10-MW semi-submersible FOWT was investigated for vibration alleviation and load reduction. Considering the hydrodynamic and mooring effect, a four degrees-of-freedom (DOFs) (platform surge and pitch motions, tower fore-aft bending, and TMD translation) simplified dynamic model for the 10-MW semi-submersible FOWT is established based on D’Alembert’s principle. Then, the parameter estimation is conducted based on the Levenberg–Marquardt (LM) algorithm, and the simplified dynamic model was further verified by comparing the output responses with FAST and the proposed model. Furthermore, the exhaustive search (ES) and genetic algorithm (GA) are embedded into the simplified dynamic model to optimize the TMD parameters. Finally, a fully coupled time-domain simulation for all the selected environmental conditions is conducted in FAST, and the vibration suppression performance of the optimized TMD design for the 10-W semi-submersible FOWT was further examined and analyzed.

Design and Aero-Elastic Simulation of a 5MW Floating Vertical Axis Wind Turbine

2012 ◽  
Author(s):  
Luca Vita ◽  
Uwe S. Paulsen ◽  
Helge A. Madsen ◽  
Per H. Nielsen ◽  
Petter A. Berthelsen ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Wind Waves ◽  
Vertical Axis ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
The European Union ◽  
Vertical Axis Wind Turbine ◽  
Floating Platform ◽  
Mooring Lines ◽  
Sea Bed

This paper deals with the design of a 5MW floating offshore Vertical Axis Wind Turbine (VAWT). The design is based on a new offshore wind turbine concept (DeepWind concept), consisting of a Darrieus rotor mounted on a spar buoy support structure, which is anchored to the sea bed with mooring lines [1]. The design is carried out in an iterative process, involving the different sub-components and addressing several conflicting constraints. The present design does not aim to be the final optimum solution for this concept. Instead, the goal is to have a baseline model, based on the present technology, which can be improved in the future with new dedicated technological solutions. The rotor uses curved blades, which are designed in order to minimize the gravitational loads and to be produced by the pultrusion process. The floating platform is a slender cylindrical structure rotating along with the rotor, whose stability is achieved by adding ballast at the bottom. The platform is connected to the mooring lines with some rigid arms, which are necessary to absorb the torque transmitted by the rotor. The aero-elastic simulations are carried out with Hawc2, a numerical solver developed at Risø-DTU. The numerical simulations take into account the fully coupled aerodynamic and hydrodynamic loads on the structure, due to wind, waves and currents. The turbine is tested in operative conditions, at different sea states, selected according to the international offshore standards. The research is part of the European project DeepWind (2010–2014), which has been financed by the European Union (FP7-Future Emerging Technologies).

Coupled Numerical Analysis of a Concept TLB Type Floating Offshore Wind Turbine

2019 ◽  
Author(s):  
Iman Ramzanpoor ◽  
Martin Nuernberg ◽  
Longbin Tao
Keyword(s):  
Wind Turbine ◽  
Renewable Energy Sources ◽  
Second Order ◽  
Offshore Wind ◽  
Design Stage ◽  
Offshore Wind Turbine ◽  
Clear Understanding ◽  
Mooring System ◽  
Floating Platform ◽  
Floating Offshore Wind Turbine

Abstract The main drivers for the continued decarbonisation of the global energy market are renewable energy sources. Moreover, the leading technological solutions to achieve this are offshore wind turbines. As installed capacity has been increasing rapidly and shallow water near shore sites are exhausted, projects will need to be developed further from shore and often in deeper waters, which will pose greater technical challenges and constrain efforts to reduce costs. Current floating platform solutions such as the spar and semi-submersible rely on large amounts of ballast and complex structural designs with active stabilisation systems for stability of the floating offshore wind turbine platform (FOWT). The primary focus of this study is to present a design concept and mooring arrangement for an alternative floating platform solution that places emphasis on the mooring system to achieve stability for a FOWT. The tension leg buoy (TLB) is designed to support future 10MW offshore wind turbine generators. This paper presents the numerical methodology used for a coupled hydro-elastic analysis of the floater and mooring system under combined wind, wave and current effects. A concept TLB design is presented and its platform motion and mooring line tension characteristics are analysed for a three-hour time domain simulation representing operating and survival conditions in the northern North Sea with water depths of 110 metres. The importance of wave drift forces and the other non-linear excitation forces in the concept design stage are evaluated by comparing the motion and tension responses of three different numerical simulation cases with increasing numerical complexity. The preliminary TLB system design demonstrated satisfactory motion response for the operation of a FOWT and survival in a 100-year storm condition. The results show that accounting for second-order effect is vital in terms of having a clear understanding of the full behaviour of the system and the detailed response characteristics in operational and survival conditions. Extreme loads are significantly reduced when accounting for the second-order effects. This can be a key aspect to not overdesign the system and consequently achieve significant cost savings.

Numerical Design of a Floating Offshore Wind Turbine Large Scale Model for Control Purposes

2021 ◽  
Author(s):  
Federico Taruffi ◽  
Simone Di Carlo ◽  
Sara Muggiasca ◽  
Alessandro Fontanella
Keyword(s):  
Numerical Model ◽  
Wind Turbine ◽  
Large Scale ◽  
Offshore Wind ◽  
Scale Model ◽  
Offshore Wind Turbine ◽  
Floating Platform ◽  
Floating Offshore Wind Turbine ◽  
Numerical Design ◽  
Blue Growth

Abstract This paper deals with the numerical design of a floating offshore wind turbine outdoor large-scale prototype based on the DTU 10MW. The objective of this work is to develop a numerical simulation environment for the design of an outdoor scaled prototype. The numerical model is realized coupling the preliminary designed Blue Growth Farm large-scale turbine model with a traditional floater, the OC3 spar buoy. The numerical model is used to evaluate the loads associated with the wind turbine when combined to a floating foundation, with the focus on the coupling between the dynamics of the control system and the one of the floating platform. In addition to this, also the consistency of loads on crucial turbine components is an interesting test bench for the evaluation of the dynamical effects and drives the final design of the physical model.

scholarly journals Effects of Second-Order Hydrodynamics on the Dynamic Responses and Fatigue Damage of a 15 MW Floating Offshore Wind Turbine

2021 ◽  
Vol 9 (11) ◽  
pp. 1232
Author(s):  
Xuan Mei ◽  
Min Xiong
Keyword(s):  
Wind Turbine ◽  
Fatigue Damage ◽  
Second Order ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Extreme Condition ◽  
Offshore Wind Turbine ◽  
Floating Platform ◽  
Floating Offshore Wind Turbine ◽  
The Cost

In order to investigate the effects of second-order hydrodynamic loads on a 15 MW floating offshore wind turbine (FOWT), this study employs a tool that integrates AQWA and OpenFAST to conduct fully coupled simulations of the FOWT subjected to wind and wave loadings. The load cases covering normal and extreme conditions are defined based on the met-ocean data observed at a specific site. The results indicate that the second-order wave excitations activate the surge mode of the platform. As a result, the surge motion is increased for each of the examined load case. In addition, the pitch, heave, and yaw motions are underestimated when neglecting the second-order hydrodynamics under the extreme condition. First-order wave excitation is the major contributor to the tower-base bending moments. The fatigue damage of the tower-base under the extreme condition is underestimated by 57.1% if the effect of second-order hydrodynamics is ignored. In addition, the accumulative fatigue damage over 25 years at the tower-base is overestimated by 16.92%. Therefore, it is suggested to consider the effects of second-order wave excitations of the floating platform for the design of the tower to reduce the cost of the FOWT.

Experimental Validation for Motion of a SPAR-Type Floating Offshore Wind Turbine Using 1/22.5 Scale Model

2009 ◽  
Author(s):  
Tomoaki Utsunomiya ◽  
Tomoki Sato ◽  
Hidekazu Matsukuma ◽  
Kiyokazu Yago
Keyword(s):  
Wind Turbine ◽  
Simulation Method ◽  
Offshore Wind ◽  
Irregular Waves ◽  
Scale Model ◽  
Offshore Wind Turbine ◽  
Floating Offshore Wind Turbine ◽  
Wave Basin ◽  
Tank Experiment ◽  
Made In

In this paper, motion of a SPAR-type floating offshore wind turbine (FOWT) subjected to wave loadings is examined. The proposed prototype FOWT mounts a 2MW wind turbine of down-wind type, whose rotor diameter is 80m and hub-height 55m. The SPAR-type floating foundation measures 60m in draft, having circular sections whose diameter is 12m at the lower part, 8.4m at the middle (main) part and 4.8m at the upper part. The FOWT is to be moored by a conventional anchor-chain system. In order to design such a FOWT system, it is essential to predict the motion of the FOWT subjected to environmental loadings such as irregular waves, turbulent winds, currents, etc. In this paper, the motion of the FOWT subjected to regular and irregular waves is examined together with the application of steady horizontal force corresponding to steady wind. The wave-tank experiment is made in the deep sea wave-basin at NMRI (National Maritime Research Institute), using a 1/22.5 scale model of the prototype FOWT. The experimental results are compared with the numerical simulation results for validation of the simulation method.

scholarly journals Wind and Wave Disturbances Compensation to Floating Offshore Wind Turbine Using Improved Individual Pitch Control Based on Fuzzy Control Strategy

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Feng Yang ◽  
Qing-wang Song ◽  
Lei Wang ◽  
Shan Zuo ◽  
Sheng-shan Li
Keyword(s):  
Fuzzy Control ◽  
Wind Turbine ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Platform ◽  
Floating Offshore Wind Turbine ◽  
Pitch Control ◽  
Wave Disturbances ◽  
Fatigue Loads ◽  
Individual Pitch Control

Due to the rich and high quality of offshore wind resources, floating offshore wind turbine (FOWT) arouses the attentions of many researchers. But on a floating platform, the wave and wind induced loads can significantly affect power regulation and vibration of the structure. Therefore, reducing these loads becomes a challenging part of the design of the floating system. To better alleviate these fatigue loads, a control system making compensations to these disturbances is proposed. In this paper an individual pitch control (IPC) system integrated with disturbance accommodating control (DAC) and model prediction control (MPC) through fuzzy control is developed to alleviate the fatigue loads. DAC is mainly used to mitigate the effects of wind disturbance and MPC counteracts the effects of wave on the structure. The new individual pitch controller is tested on the NREL offshore 5 MW wind turbine mounted on a barge with a spread-mooring system, running in FAST, operating above-rated condition. Compared to the original baseline collective pitch control (CPC) (Jonkman et al., 2007), the IPC system shows a better performance in reducing fatigue loads and is robust to complex wind and wave disturbances as well.

Impact of Rotor Misalignment due to Platform Motions on Floating Offshore Wind Turbine Blade Loads

2019 ◽  
Author(s):  
Rachael E. Smith ◽  
Ajit C. Pillai ◽  
Gavin Tabor ◽  
Philipp R. Thies ◽  
Lars Johanning
Keyword(s):  
Wind Turbine ◽  
Wind Farm ◽  
Structural Response ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Offshore Wind Turbine ◽  
Unsteady Loading ◽  
Future Work ◽  
The Impact ◽  
Blade Loads

Abstract The rotor of a horizontal-axis floating offshore wind turbine is more frequently misaligned with the oncoming wind than that of a fixed offshore or onshore wind turbine due to the pitch and yaw motions of the floating support structure. This can lead to increased unsteady loading and fatigue on the components beyond those considered in the standard load cases. In this work, the Simulator fOr Wind Farm Applications (SOWFA) tool within the CFD toolbox OpenFOAM is used to perform simulations of a wind turbine at different stationary angles to the oncoming wind flow that a floating wind turbine may experience, so that the impact of misaligned flow on power production and blade loading can be studied. The turbine is modelled using an actuator line method which is coupled with NREL’s aeroelastic code FAST to compute the structural response. The results of this study will be used in future work to optimise the rotor geometry of a floating offshore wind turbine.

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