Performance Specifications for Real-Time Hybrid Testing of 1:50-Scale Floating Wind Turbine Models

Hall, Matthew; Moreno, Javier; Thiagarajan, Krish

doi:10.1115/omae2014-24497

Cited by 22 publications

(16 citation statements)

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“…In our setup, a ducted fan is used to apply the force representing the total rotor thrust that is computed in real time by a numerical model. Other hybrid methods are discussed in Chabaud et al and Hall et al Recently, wires have been used to introduce the rotor thrust in hybrid test campaigns for horizontal axis wind turbines in Bachynski et al and Hall and Goupee and for vertical axis wind turbines . An effort to define the specifications and requirements of hybrid testing methods has been carried out in Hall et al and Müller et al The importance of non‐linear hydrodynamics and wind loading in the low‐frequency dynamics of floating wind turbine has been studied in previous publications.…”

Section: Introductionmentioning

confidence: 99%

Low‐frequency dynamics of a floating wind turbine in wave tank–scaled experiments with SiL hybrid method

2019

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The design of floating wind turbines needs the validation of numerical models against measurements obtained from experiments that accurately represent the system dynamics. This requires solving the conflict in the scaling of the hydrodynamic and aerodynamic forces that arises in tests with wind and waves. To sort out this conflict, we propose a hybrid testing method that uses a ducted fan to replace the rotor and introduce a force representing the aerodynamic thrust. The force is obtained from a simulation of the rotor coupled in real time with the measured platform displacements at the basin. This method is applied on a test campaign of a semisubmersible wind turbine with a scale factor of 1/45. The experimental data are compared with numerical computations using linear and non-linear hydrodynamic models. Pitch decays in constant wind show a good agreement with computations, demonstrating that the hybrid testing method correctly introduces the aerodynamic damping. Test cases with constant wind and irregular waves show better agreement with the simulations in the power spectral density's (PSD's) low-frequency region when non-linear hydrodynamics are computed. In cases with turbulent wind at rated wind speed, the low-frequency platform motions are dominated by the wind, hiding the differences from hydrodynamic non-linearities. In these conditions, the agreement between experiments using the proposed hybrid method and computations is good in all the frequency range both for the linear and the non-linear hydrodynamic models. Conversely, for turbulent winds producing lower rotor thrust, non-linear hydrodynamics are relevant for the simulation of the low-frequency system dynamics.

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Section: Introductionmentioning

confidence: 99%

Low‐frequency dynamics of a floating wind turbine in wave tank–scaled experiments with SiL hybrid method

2019

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“…When the experimental goal is to qualify the global performance of the system, a so-called "realtime hybrid model testing" approach may be applied: in the case of the FWT in the wave basin, this implies that the aerodynamic forces are actuated upon the physical model according to simultaneous (real-time) simulations of the turbine rather than being generated by a small-scale physical turbine [1,[12][13][14]. Real-time hybrid model testing will be referred to as ReaTHM TM testing (a trademark of MARINTEK) in the following.…”

Section: Introductionmentioning

confidence: 99%

Real-Time Hybrid Model Testing of a Braceless Semi-Submersible Wind Turbine: Part II — Experimental Results

Bachynski

Thys

Sauder

et al. 2016

Volume 6: Ocean Space Utilization; Ocean Renewable Energy

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Real-Time Hybrid Model (ReaTHM) tests of a braceless semi-submersible wind turbine were carried out at MARIN-TEK's Ocean Basin in 2015. The tests sought to evaluate the performance of the floating wind turbine (FWT) structure in environmental conditions representative of the Northern North Sea. In order to do so, the tests employed a new hybrid testing method, wherein simulated aerodynamic loads were applied to the physical structure in the laboratory. The test method was found to work well, and is documented in [1].The present work describes some of the experimental results. The test results showed a high level of repeatability, and permitted accurate investigation of the coupled responses of a FWT, including unique conditions such as blade pitch faults. For example, the influence of the wind turbine controller can be seen in decay tests in pitch and surge. In regular waves, aerodynamic loads due to constant wind had little influence on the structure motions (except for the mean offsets). Tests in irregular waves with and without turbulent wind are compared directly, and the influence of the wave-frequency motions on the aerodynamic damping of wind-induced low-frequency motions can be observed.

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“…In this, the wind turbine aerodynamics are modeled numerically rather than physically, and this simulation is dynamically coupled with the remaining floating structure experiment. A motion tracking system transmits physical platform motions to the wind turbine simulation, and an actuation system applies the calculated aerodynamic forces onto the floating platform experiment …”

Section: Introductionmentioning

confidence: 99%

Validation of a hybrid modeling approach to floating wind turbine basin testing

Hall

Goupee

2018

Wind Energy

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Hybrid modeling combining physical tests and numerical simulations in real time opens new opportunities in floating wind turbine research. Wave basin testing is an important validation step for floating support structure design, but current methods are limited by scaling problems in the aerodynamic loadings. Applying wind turbine loads with an actuation system controlled by a simulation that responds to the basin test offers a way to avoid scaling problems and reduce cost barriers for floating wind turbine design validation in realistic coupled conditions. In this work, a cable-based hybrid coupling approach is developed and implemented for 1:50-scale wave basin tests with the DeepCwind semisubmersible floating wind turbine. Tests are run with thrust loads provided by a numerical wind turbine model. Matching tests are run with physical wind loads using an above-basin wind maker. When the numerical submodel is set to match the aerodynamic performance of the physical scaled wind turbine, the results show good agreement with purely physical wind-wave tests, validating the hybrid model approach. Further hybrid model tests with simulated true-to-scale dynamic thrust loads and wind turbulence show noticeable differences and demonstrate the value of a hybrid model approach for improving the true-to-scale realism of floating wind turbine basin tests. KEYWORDS basin test, floating, hybrid model, hybrid testing, wind turbine 1 INTRODUCTION Scale-model testing of floating wind turbines, often considered an essential validation step in the design process, faces a difficult scaling problem. Two different fluid-structure-interaction domains need to be scaled simultaneously: the hydrodynamics of the floating support structure and the aerodynamics of the wind turbine. The dominance of different nondimensional ratios in each makes scaling without compensation cause discrepancies in the results. For example, a scaled-down floating wind turbine may require higher wind speeds and blade pitch adjustments to achieve the correct thrust force. 1 On top of this, there is the challenge of recreating a wind turbine's mechanical properties at small scale. For less advanced facilities, even providing controlled wind conditions above the wave basin may not be feasible. All these factors contribute to the scaling difficulty in floating wind turbine experiments. A number of approaches have arisen in recent years to counter some of these challenges, especially to do with the turbine aerodynamics. Müller et al review many of the challenges and options for floating wind turbine basin testing. 2 The most direct approach is to compensate for performance reductions through changes to the rotor geometry. Martin et al explored enlarging the blades, using special airfoils, and adding leading edge roughness to counter the lowered Reynolds number. 3 Research at the University of Maine and the Maritime Research Institute of the Netherlands(MARIN) showed that using low-Reynolds number airfoils with enlarged chord lengths can come close to matching true-to-s...

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Performance Specifications for Real-Time Hybrid Testing of 1:50-Scale Floating Wind Turbine Models

Cited by 22 publications

References 0 publications

Low‐frequency dynamics of a floating wind turbine in wave tank–scaled experiments with SiL hybrid method

Low‐frequency dynamics of a floating wind turbine in wave tank–scaled experiments with SiL hybrid method

Real-Time Hybrid Model Testing of a Braceless Semi-Submersible Wind Turbine: Part II — Experimental Results

Validation of a hybrid modeling approach to floating wind turbine basin testing

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