Active load reduction using individual pitch, based on local blade flow measurements

Larsen, Torben J.; Madsen, Helge Aagaard; Thomsen, Kenneth

doi:10.1002/we.141

Cited by 144 publications

(103 citation statements)

References 4 publications

(5 reference statements)

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“…Bossanyi [1] and Larsen et al [2] investigate the fatigue load alleviation potential of an improved blade pitch control. Larsen et al [2] reach to the conclusion that by adopting a cyclic blade pitching the apwise fatigue loads can be reduced up to 15 % with respect to the normal collective pitch, and a 28 % reduction would be instead achieved by pitching each blade independently.…”

Section: Introductionmentioning

confidence: 99%

Stability investigation of an airfoil section with active flap control

Bergami

Gaunaa

2009

Wind Energy

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This paper presents a method to determine utter and divergence instability limits for a 2D airfoil section tted with active control. The control system consists of a ap-like deformable trailing edge actuator, maneuvered by algorithms based on measurements of either heave displacement, local angle of attack, or pressure di erence over the airfoil. The purpose of the trailing edge actuator is to reduce uctuations in the aerodynamic forcing and a signi cant potential for active fatigue load alleviation has been reported in recent studies.Besides the control, the full model of the ap equipped airfoil also comprises a structural and an aerodynamic part. The in-plane motion and deformation of the 2D structure are described by three degrees of freedom: heave translation, pitch rotation and ap de ection. A potential ow model provides the aerodynamic forces and their distribution, the unsteady aerodynamics are described using an indicial function approximation. Stability of the full aeroservoelastic system is determined through eigenvalue analysis.Validation is carried out against a reimplementation of the recursive method by Theodorsen and Garrick for`exure-torsion-aileron' utter. The implemented stability tool is then applied to an airfoil section representative of a wind turbine blade with active ap control. It is thereby observed that the airfoil stability limits are signi cantly modi ed by the presence of the ap, and they depend on several parameters: ap structural characteristics, type of control, control gain factors and time lag.

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Section: Introductionmentioning

confidence: 99%

Stability investigation of an airfoil section with active flap control

Bergami

Gaunaa

2009

Wind Energy

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“…load conditions, power generation, noise aspects, and fatigue and extreme loads (Elliott and Cadogan, 1990;Larsen et al, 2005;Barlas et al, 2012;Madsen, 2014;St. Martin et al, 2016) The wind of interest is the free undisturbed turbulent inflow, but at the location of the wind turbine rotor.…”

Section: Introductionmentioning

confidence: 99%

Free-flow wind speed from a blade-mounted flow sensor

et al. 2018

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Abstract. This paper presents a method for obtaining the free-inflow velocities from a 3-D flow sensor mounted on the blade of a wind turbine.From its position on the rotating blade, e.g. one-third from the tip, a blade-mounted flow sensor (BMFS) is able to provide valuable information about the turbulent sheared inflow in different regions of the rotor. At the rotor, however, the inflow is affected by the wind turbine, and in most cases the wind of interest is the inflow that the wind turbine is exposed to, i.e. the free-inflow velocities.The current method applies a combination of aerodynamic models and procedures to estimate the induced velocities, i.e. the disturbance of the flow field caused by the wind turbine. These velocities are subtracted from the flow velocities measured by the BMFS to obtain the free-inflow velocities. Aeroelastic codes, like HAWC2, typically use a similar approach to calculate the induction, but they use it for the reversed process, i.e. they add the induction to the free inflow to get the flow velocities at the blades, which are required to calculate the resulting aerodynamic forces.The aerodynamic models included in the current method comprise models based on blade element momentum (BEM) for axial and tangential induction, a radial induction model and tip loss correction, and models for skew and dynamic inflow.It is shown that the method is able to calculate the free-inflow velocities with high accuracy when applied to aeroelastic HAWC2 simulations with a stiff structural model while some deviations are seen in simulations with a flexible structure.Furthermore, the method is tested on simulations performed by a flexible structural model coupled with a large-eddy simulation (LES) flow solver. The results of this higher-fidelity verification confirm the HAWC2-based conclusion.

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“…Other approaches, such as taking the variance of a stress are not a direct representation of fatigue, as mentioned in [8]. In [9][10][11], loading reductions are achieved by controlling the pitch of each blade independently, but the damage is estimated offline. In [8], controllers for wind turbines were designed by approximating fatigue load by an analytical function based on spectral moments, where it is assumed that the stress is an output from a given linear system with Gaussian white noise input, but measurements are not directly used.…”

Section: Introductionmentioning

confidence: 99%

Fatigue damage estimation and data‐based control for wind turbines

Barradas-Berglind

Wisniewski

Soltani

2015

IET Control Theory & Applications

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Abstract:The focus of this work is on fatigue estimation and data-based controller design for wind turbines. The main purpose is to include a model of the fatigue damage of the wind turbine components in the controller design and synthesis process. This study addresses an online fatigue estimation method based on hysteresis operators, which can be used in control loops. The authors propose a data-based model predictive control (MPC) strategy that incorporates an online fatigue estimation method through the objective function, where the ultimate goal in mind is to reduce the fatigue damage of the wind turbine components. The outcome is an adaptive or self-tuning MPC strategy for wind turbine fatigue damage reduction, which relies on parameter identification on previous measurement data. The results of the proposed strategy are compared with a baseline model predictive controller.

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Active load reduction using individual pitch, based on local blade flow measurements

Cited by 144 publications

References 4 publications

Stability investigation of an airfoil section with active flap control

Stability investigation of an airfoil section with active flap control

Free-flow wind speed from a blade-mounted flow sensor

Fatigue damage estimation and data‐based control for wind turbines

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