scholarly journals Wind Turbine Controller to Mitigate Structural Loads on a Floating Wind Turbine Platform

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Paul A. Fleming ◽  
Antoine Peiffer ◽  
David Schlipf
Keyword(s):  
Wind Turbine ◽  
Control Design ◽  
Simulation Tool ◽  
Floating Platform ◽  
Design Work ◽  
Wave Disturbances ◽  
Control Modules ◽  
Elastic Simulation ◽  
Bending Loading ◽  
Fully Coupled

This paper summarizes the control design work that was performed to optimize the controller of a wind turbine on the WindFloat structure. The WindFloat is a semisubmersible floating platform designed to be a support structure for a multimegawatt power-generating wind turbine. A controller developed for a bottom-fixed wind turbine configuration was modified for use when the turbine is mounted on the WindFloat platform. This results in an efficient platform heel resonance mitigation scheme. In addition, several control modules, designed with a coupled linear model, were added to the fixed-bottom baseline controller. The approach was tested in a fully coupled nonlinear aero-hydro-elastic simulation tool in which wind and wave disturbances were modeled. This testing yielded significant improvements in platform global performance and tower-base bending loading.

scholarly journals Wind Turbine Controller to Mitigate Structural Loads on a Floating Wind Turbine Platform

2016 ◽  
Author(s):  
Paul A. Fleming ◽  
Antoine Peiffer ◽  
David Schlipf
Keyword(s):  
Wind Turbine ◽  
Control Design ◽  
Simulation Tool ◽  
Floating Platform ◽  
Design Work ◽  
Wave Disturbances ◽  
Global Performance ◽  
Control Modules ◽  
Bending Loading ◽  
Fully Coupled

This paper summarizes the control design work that was performed to optimize the controller of a wind turbine on the WindFloat structure. The WindFloat is a semi-submersible floating platform designed to be a support structure for a multi-megawatt power-generating wind turbine. A controller developed for a bottom-fixed wind turbine configuration was modified for use when the turbine is mounted on the WindFloat platform. This results in an efficient platform heel resonance mitigation scheme. In addition several control modules, designed with a coupled linear model, were added to the fixed-bottom baseline controller. The approach was tested in a fully coupled nonlinear aero-hydroelastic simulation tool in which wind and wave disturbances were modeled. This testing yielded significant improvements in platform global performance and tower-base-bending loading.

Validation of a Novel Floating Wind Turbine Simulation Tool via Benchmarking: Case Study of a Semi-Submersible Platform

2021 ◽  
Author(s):  
Aengus John Connolly ◽  
Gerard O'Mahony
Keyword(s):  
Finite Element ◽  
Structural Analysis ◽  
Numerical Modelling ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Offshore Wind ◽  
Simulation Tool ◽  
Offshore Wind Turbines ◽  
Structural Simulation ◽  
Fully Coupled

Abstract This paper describes the validation of a novel floating wind turbine simulation tool based on an existing finite element offshore structural analysis solver that recently has been extended to simulate offshore wind turbines. Given the growing importance of offshore wind in the decarbonization strategy of many countries, and particularly the predicted exponential future growth in floating offshore wind, the requirement for validated numerical modelling tools to support detailed engineering design is now greater than ever. The tool combines a unique structural analysis solver incorporating a 3D hybrid beam-column element featuring fully-coupled axial, torsional and bending deformation modes, with the open-source aerodynamic modelling software FAST, to enable it to perform fully coupled aero-hydro-structural simulation of offshore wind turbines. The validation process focuses on a floating semi-submersible platform hosting a 5MW turbine, which is the reference model used in the international research project Offshore Code Comparison Collaboration Continuation (OC4). This is a code-to-code verification project sponsored by the International Energy Agency (IEA) which benchmarks a range of simulation codes for offshore wind turbine modelling. Beginning with fundamental test cases, such as static equilibrium, eigen-analysis, and free-decay simulations, the scenarios advance in complexity to include current loading, regular and random wave excitation, in conjunction with both steady and turbulent wind inflow. The new tool generates results which exhibit a close correlation with the OC4 benchmark data, thereby validating the numerical modelling approach. Although primarily focused on the semi-submersible, the validation programme also considers the same 5MW turbine hosted by a jacket substructure in shallower water, illustrating the versatility of the modelling tool to simulate fixed support structures in addition to floating. Given the scope of the validation effort, this paper presents a representative sample of results only. A more comprehensive report covering the other load cases can be provided to interested readers by the authors. This paper complements the research work undertaken in OC4, further substantiating its insights into the dynamic responses of floating offshore wind turbines. The new tool offers advantages for non-linear structural simulation via its innovative finite element solution technique, and detailed hydrodynamic modelling via its established and proven numerical models. The combination underlines the benefits of exploiting synergies between offshore oil and gas and offshore wind.

Fully Coupled Aero-Hydro-Structural Simulation of New Floating Wind Turbine Concept

2018 ◽  
Author(s):  
Aengus Connolly ◽  
Marc Guyot ◽  
Marc Le Boulluec ◽  
Léna Héry ◽  
Aonghus O’Connor
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Structural Model ◽  
Capital Expenditure ◽  
Offshore Wind ◽  
Floating Platform ◽  
Simulation Methodology ◽  
Floating Wind Turbine ◽  
Floating Offshore Wind Turbines ◽  
Fully Coupled

This paper describes a fully coupled numerical simulation methodology which is tailored towards floating offshore wind turbines. The technique assembles three key components; an aerodynamic model of the applied wind loads based on blade element momentum theory, a structural model of the floating platform and its associated mooring lines based on the nonlinear finite element method, and a hydrodynamic model of the wave-induced forces based on potential flow theory. The simulation methodology has been implemented in a commercial software product called ‘Flexcom Wind’, and the technical validation involves comparisons with experimental data derived from model-scale tank test facilities. The validation process centres on an innovative floating wind turbine concept developed by Eolink. Unlike most wind turbines in industry which are supported by a single mast, this patented design uses four separate pillars to connect the turbine structure to the corners of the floating platform. This unique configuration offers several advantages over conventional designs, including a more even stress distribution in structural members, reduced dynamic vibration, smaller floater size and lower overall capital expenditure. Data obtained from the numerical simulations combined with the empirical tests is helping to optimise the device, with a view to further improving its structural design and performance.

scholarly journals Load Estimation of Offshore Wind Turbines

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1895 ◽  
Author(s):  
Sang Lee ◽  
Matthew Churchfield ◽  
Frederick Driscoll ◽  
Senu Sirnivas ◽  
Jason Jonkman ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
Wind Turbine ◽  
Gulf Of Maine ◽  
Offshore Wind ◽  
Simulation Tool ◽  
Floating Platform ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Equivalent Load ◽  
Turbine Wake

The influence of 3 MW Hywind-II wind turbine wakes from an upstream offshore floating wind turbine on a downstream turbine with a separation distance of seven rotor diameters was studied for a site in the Gulf of Maine. The turbines and the platforms were subjected to atmospheric boundary layer flows. Various sensitivity studies on fatigue loads with respect to the positions of the downstream turbine were performed and validated with a large-eddy simulation tool. In particular, the effect of various lateral positions of the downstream turbine relative to the upstream turbine were considered using time-series turbine wake data generated from the large-eddy simulation tool which served as an input to an aero-elastic wind turbine model to assess the loads. The load response from the rotor, tower, and the floating platform for the downstream turbine were sensitive to the lateral offset positions where turbines that were partially exposed to upstream turbine wakes yielded significant increases in the cyclic load range. For the given set of lateral positions for the downstream turbine, the largest damage equivalent load occurred when the turbine was one rotor diameter to the left of the centerline, when looking upstream, which is the position of the turbine fully exposed to upstream turbine wake. On the other hand, the fatigue load on the downstream turbine placed on the right side of the position fully exposed to the upstream turbine wake, yielded lower stress due to the non-symmetric shape of the turbine wake. The configuration associated with the largest damage equivalent loads was further investigated in a large-eddy simulation, modeling both the upstream and downstream turbines. It was found that the energy spectra at the blade rotational frequency were a magnitude order higher for the downstream turbine, especially for surge, heave, pitch, and yaw motion of the platform. The increase of the damage equivalent load for the flapwise blade root moment was 45% compared to the upstream turbine, which can potentially reduce the turbine service life time.

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.

Elastic Deformations of Floaters for Offshore Wind Turbines: Dynamic Modelling and Sectional Load Calculations

2017 ◽  
Author(s):  
Michael Borg ◽  
Henrik Bredmose ◽  
Anders M. Hansen
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Dynamic Modelling ◽  
Wave Structure ◽  
Diffraction Theory ◽  
Offshore Wind ◽  
Simulation Tool ◽  
Simulation Tools ◽  
Global Platform ◽  
Elastic Simulation

To achieve economically and technically viable floating support structures for large 10MW+ wind turbines, structural flexibility may increase to the extent that becomes relevant to incorporate along with the corresponding physical effects within aero-hydro-servo-elastic simulation tools. Previous work described a method for the inclusion of substructural flexibility of large-volume substructures, including wave-structure interactions through linear radiation-diffraction theory. Through an implementation in the HAWC2 simulation tool, it was shown that one may incorporate the effects of additional modes on substructure and wind turbine response as well as predict the excitation of substructure flexible modes. This work goes one step further and describes a method to calculate internal substructural stresses that includes dynamic effects. In dynamic calculations, the substructure flexibility is considered through a reduced set of modes, selected based on their relevance to the external load frequency range, and represented with a superelement. The implementation of this method in aeroelastic simulation tool HAWC2 and wave-structure analysis program WAMIT is described, highlighting the practical challenges. A case study of the DTU 10MW Reference Wind Turbine installed on the Triple Spar concept is presented to illustrate the method. The results show that the substructure flexible modes, global platform motion and wind turbine loads can influence sectional loads within the substructure.

Fully-Coupled Aero-Hydrodynamic Simulation of Floating Offshore Wind Turbines by Different Simulation Methods

2018 ◽  
Author(s):  
Ping Cheng ◽  
Decheng Wan
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Platform ◽  
Hydrodynamic Simulation ◽  
Floating Offshore Wind Turbine ◽  
Floating Offshore Wind Turbines ◽  
Fully Coupled

To accurately predict the critical loads due to wind and wave is one of the common challenges in designing a floating offshore wind turbine (FOWT). The fully-coupled aero-hydrodynamic simulation of a floating offshore wind turbine, the NREL-5MW baseline wind turbine mounted on a semi-submersible floating platform, is conducted with two methods. Firstly, the in-house code naoe-FOAM-os-SJTU, which is developed on the open source platform OpenFOAM and coupled with the overset grid technique, is employed for the directly CFD computations. And another in-house code FOWT-UALM-SJTU developed by coupling the unsteady actuator line model (UALM) with naoe-FOAM-SJTU is also utilized for coupling simulations. In both models, the three-dimensional Reynolds Averaged Navier-Stokes (RANS) equations are solved with the turbulence model k-ω SST, and the Pressure-Implicit with Splitting of Operations (PISO) algorithm is applied to solve the pressure-velocity coupling equations. Both two solvers provide reasonable results of main aerodynamic loads as well as the main hydrodynamic forces. The FOWT-UALM-SJTU solver achieves better computational efficiency by simplifying the blade structure as actuator line models, while the naoe-FOAM-os-SJTU solver provides more accurate detailed flow information near the turbine blades.

scholarly journals Control design, implementation, and evaluation for an in-field 500 kW wind turbine with a fixed-displacement hydraulic drivetrain

2018 ◽  
Vol 3 (2) ◽  
pp. 615-638 ◽  
Author(s):  
Sebastiaan Paul Mulders ◽  
Niels Frederik Boudewijn Diepeveen ◽  
Jan-Willem van Wingerden
Keyword(s):  
Wind Turbine ◽  
Control Design ◽  
Business Case ◽  
Torque Control ◽  
Offshore Wind ◽  
Pelton Turbine ◽  
Torque Control Strategy ◽  
Control Scheme ◽  
Active Valve ◽  
Electrical Generator

Abstract. The business case for compact hydraulic wind turbine drivetrains is becoming ever stronger, as offshore wind turbines are getting larger in terms of size and power output. Hydraulic transmissions are generally employed in high-load systems and form an opportunity for application in multi-megawatt turbines. The Delft Offshore Turbine (DOT) is a hydraulic wind turbine concept replacing conventional drivetrain components with a single seawater pump. Pressurized seawater is directed to a combined Pelton turbine connected to an electrical generator on a central multi-megawatt electricity generation platform. This paper presents the control design, implementation, and evaluation for an intermediate version of the ideal DOT concept: an in-field 500 kW hydraulic wind turbine. It is shown that the overall drivetrain efficiency and controllability are increased by operating the rotor at maximum rotor torque in the below-rated region using a passive torque control strategy. An active valve control scheme is employed and evaluated in near-rated conditions.

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