Linear coupled model for floating wind turbine control

Fontanella, Alessandro; Bayati, Ilmas; Belloli, Marco

doi:10.1177/0309524x18756970

Cited by 20 publications

(22 citation statements)

References 8 publications

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“…The model has 16 states and couples the aero-hydro-servo dynamics but with a mechanical model of a single rigid body only. A recent control-oriented model [18] uses hydrodynamic coefficients from a panel code, valid also for nonslender structures. Both of the latter models, however, neglect the tower flexibility.…”

Section: Reduced-order Modelingmentioning

confidence: 99%

Multibody modeling for concept-level floating offshore wind turbine design

Lemmer

Luhmann³

et al. 2020

Multibody Syst Dyn

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Existing Floating Offshore Wind Turbine (FOWT) platforms are usually designed using static or rigid-body models for the concept stage and, subsequently, sophisticated integrated aero-hydro-servo-elastic models, applicable for design certification. For the new technology of FOWTs, a comprehensive understanding of the system dynamics at the concept phase is crucial to save costs in later design phases. This requires low-and medium-fidelity models. The proposed modeling approach aims at representing no more than the relevant physical effects for the system dynamics. It consists, in its core, of a flexible multibody system. The applied Newton-Euler algorithm is independent of the multibody layout and avoids constraint equations. From the nonlinear model a linearized counterpart is derived. First, to be used for controller design and second, for an efficient calculation of the response to stochastic load spectra in the frequency-domain. From these spectra the fatigue damage is calculated with Dirlik's method and short-term extremes by assuming a normal distribution of the response. The set of degrees of freedom is reduced, with a response calculated only in the two-dimensional plane, in which the aligned wind and wave forces act. The aerodynamic model is a quasistatic actuator disk model. The hydrodynamic model includes a simplified radiation model, based on potential flow-derived added mass coefficients and nodal viscous drag coefficients with an approximate representation of the second-order slow-drift forces. The verification through a comparison of the nonlinear and the linearized model against a higher-fidelity model and experiments shows that even with the simplifications, the system response magnitude at the system eigenfrequencies and the forced response magnitude to wind and wave forces can be well predicted. One-hour simulations complete in about 25 seconds and even less in the case of the frequency-domain model. Hence, large sensitivity studies and even multidisciplinary optimizations for systems engineering approaches are possible.

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Section: Reduced-order Modelingmentioning

confidence: 99%

Multibody modeling for concept-level floating offshore wind turbine design

Lemmer

Luhmann³

et al. 2020

Multibody Syst Dyn

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“…Experimental results presented in this work directly assessed the effect of unsteady aerodynamic loads on the wind turbine response. Ongoing research by the authors is meant to compare this approach with the prediction of a simple FOWT linear model, like the one presented in [20], using as input data from unsteady loads measured in imposed motion experimental tests [9].…”

Section: Discussionmentioning

confidence: 99%

Numerical and Experimental Wind Tunnel Analysis of Aerodynamic Effects on a Semi-Submersible Floating Wind Turbine Response

Fontanella

Bayati

Taruffi

et al. 2019

Volume 10: Ocean Renewable Energy

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This paper presents the main results of an experimental campaign about the DeepCwind semi-submersible floating offshore wind turbine (FOWT), that was carried out at Politecnico di Milano wind tunnel, adopting a hybrid hardware-in-the-loop (HIL) testing technique. Differently from previous works by the authors, this further analysis herein reported, is specifically focused on evaluating the effects of aerodynamic loads on the FOWT platform motions. In order to reproduce the FOWT response to combined wind and waves in a wind tunnel, exploiting the high-quality flow, a HIL system was used. The aerodynamic and rotor loads were reproduced by means of a wind turbine scale model operating inside the wind tunnel and were combined with numerically generated wave loads for real-time integration of the FOWT rigid-body motion equations. The resulting platform motions were imposed to the wind turbine scale model by a hydraulic actuation system. A series of HIL tests was performed to assess the rotor loads effect on the FOWT response. Free-decay tests in still water under laminar un-sheared wind were carried out to evaluate how the aerodynamic forcefield modifies the platform modes frequency and damping. Irregular wave tests for different steady winds were performed to investigate the dependency of platform motion from the wind turbine operating conditions. A FAST v8 model of the studied floating system was developed to support the analysis and numerical simulations were performed to reproduce environmental conditions equivalent to those of the experimental tests. The FAST model prediction capability is discussed against HIL wind tunnel tests results.

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“…where k P and k I are the proportional and integral gains, which are tuned following the model-based approach of Fontanella et al (2018) to achieve the maximum damping for the platform pitch mode and for the drivetrain mode. A gain scheduling factor is introduced to adjust the PI controller gains as the wind speed varies.…”

Section: Definition Of a Reference Floating Wind Turbinementioning

confidence: 99%

Model-based design of a wave-feedforward control strategy in ﬂoating wind turbines

Fontanella¹,

Al²,

Wingerden³

et al. 2021

Preprint

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Abstract. Floating wind turbines rely on feedback-only control strategies to mitigate the effects of wave excitation. Improved power generation and lower fatigue loads can be achieved by including information about the incoming waves into the wind turbine controller. In this paper, a wave-feedforward control strategy is developed and implemented in a 10 MW floating wind turbine. A linear model of the floating wind turbine is established and utilized to show how wave excitation affects the wind turbine rotor speed output, and that collective-pitch is an effective control input to reject the wave disturbance. Based on the inversion of the same model, a feedforward controller is designed, and its performance is examined by means of linear analysis. A gain-scheduling algorithm is proposed to adapt the feedforward action as the wind speed changes. Non-linear time-domain simulations prove that the proposed feedforward control strategy is an effective way of reducing rotor speed oscillations and structural fatigue loads caused by waves.

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Linear coupled model for floating wind turbine control

Cited by 20 publications

References 8 publications

Multibody modeling for concept-level floating offshore wind turbine design

Multibody modeling for concept-level floating offshore wind turbine design

Numerical and Experimental Wind Tunnel Analysis of Aerodynamic Effects on a Semi-Submersible Floating Wind Turbine Response

Model-based design of a wave-feedforward control strategy in ﬂoating wind turbines

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