Yaw Systems for wind turbines – Overview of concepts, current challenges and design methods

Kim, M. G.; Dalhoff, Peter

doi:10.1088/1742-6596/524/1/012086

Cited by 44 publications

(21 citation statements)

References 10 publications

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“…In addition, a second yaw control case (Y5) is constructed, for which a higher maximum yaw rate of ω max = 5 • /s is selected. Although this significantly exceeds the capabilities of the abovementioned turbine design concepts, this case will allow to assess whether significant gains in power could be achieved by rapidly yawing turbine designs, such as low-inertia two-bladed teeter hinge wind turbines [61].…”

Section: Control Casesmentioning

confidence: 99%

Dynamic Strategies for Yaw and Induction Control of Wind Farms Based on Large-Eddy Simulation and Optimization

2018

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Abstract:In wind farms, wakes originating from upstream turbines cause reduced energy extraction and increased loading variability in downstream rows. The prospect of mitigating these detrimental effects through coordinated controllers at the wind-farm level has fueled a multitude of research efforts in wind-farm control. The main strategies in wind-farm control are to influence the velocity deficits in the wake by deviating from locally optimal axial induction setpoints on the one hand, and steering wakes away from downstream rows through yaw misalignment on the other hand. The current work investigates dynamic induction and yaw control of individual turbines for wind-farm power maximization in large-eddy simulations. To this end, receding-horizon optimal control techniques combined with continuous adjoint gradient evaluations are used. We study a 4 × 4 aligned wind farm, and find that for this farm layout yaw control is more effective than induction control, both for uniform and turbulent inflow conditions. Analysis of optimal yaw controls leads to the definition of two simplified yaw control strategies, in which wake meandering and wake redirection are exploited respectively. Furthermore it is found that dynamic yawing provides significant benefits over static yaw control in turbulent flow environments, whereas this is not the case for uniform inflow. Finally, the potential of combining overinductive axial induction control with yaw control is shown, with power gains that approximate the sum of those achieved by each control strategy separately.

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Section: Control Casesmentioning

confidence: 99%

Dynamic Strategies for Yaw and Induction Control of Wind Farms Based on Large-Eddy Simulation and Optimization

2018

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“…The deviation between the wind direction and the yaw angle of the turbine is usually averaged over several minutes and a threshold for the deviation is used to keep the turbine from constantly yawing (Burton et al, 2011). This has the effect that the turbine is in standstill mode most of the time (Kim and Dalhoff, 2014). Although the details of the yaw control depend on the manufacturer, and is commonly kept confidential, in our experience the yaw angle remains constant for about 5 to 10 min in most cases before the yaw control corrects the yaw angle according to the changed wind direction.…”

Section: Statistical Analysis Of Wind Direction Measurementsmentioning

confidence: 99%

“…A number of algorithms can be used for the computation of these kinds of optimization problems, including the intuitive game theoretic approach presented in Marden et al (2012). This algorithm has the benefit that it works on complex, nonlinear problems and does not depend on any gradients, but unfortunately it converges relatively slowly.…”

Section: (4)mentioning

confidence: 99%

“…Greedy yaw control: this reference control is derived from the baseline, it refers to the situation that every individual turbine tries to locally maximize its power output by yawing directly into the wind direction without any intentional yaw misalignment. The term greedy control was introduced by Marden et al (2012) in the scope of induction-based wind farm control.…”

Section: Evaluation Of Control Algorithmsmentioning

confidence: 99%

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Robust active wake control in consideration of wind direction variability and uncertainty

et al. 2018

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Abstract. The prospects of active wake deflection control to mitigate wake-induced power losses in wind farms have been demonstrated by large eddy simulations, wind tunnel experiments, and recent field tests. However, it has not yet been fully understood how the yaw control of wind farms should take into account the variability in current environmental conditions in the field and the uncertainty in their measurements. This research investigated the influence of dynamic wind direction changes on active wake deflection by intended yaw misalignment. For this purpose the wake model FLORIS was used together with wind direction measurements recorded at an onshore meteorological mast in flat terrain. The analysis showed that active wake deflection has a high sensitivity towards short-term wind directional changes. This can lead to an increased yaw activity of the turbines. Fluctuations and uncertainties can cause the attempt to increase the power output to fail. Therefore a methodology to optimize the yaw control algorithm for active wake deflection was introduced, which considers dynamic wind direction changes and inaccuracies in the determination of the wind direction. The evaluation based on real wind direction time series confirmed that the robust control algorithm can be tailored to specific meteorological and wind farm conditions and that it can indeed achieve an overall power increase in realistic inflow conditions. Furthermore recommendations for the implementation are given which could combine the robust behaviour with reduced yaw activity.

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“…Jeong et al 7 investigated the impact of yaw error on aeroelastic characteristics of a horizontal axis wind turbine blade. Kim et al 8 showed 131 related patents to the yaw systems and discussed that the highest number of these patents refer to load reduction design and methods. He reported that the yaw system is the second most common mechanical component that contributes to an overall failure rate.…”

Section: Introductionmentioning

confidence: 99%

Comparative study of yaw and nacelle tilt control strategies for a two-bladed downwind wind turbine

Zhao

Al-Khalifin

et al. 2018

FMRIJ

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The structural dynamics and response of a two-bladed downwind wind turbine configuration using a tilt control concept is examined based on Computational Structural Dynamics (CSD) analysis. Nacelle tilt angles of 5, 20, 35, 50 and 65 degrees are investigated based on varying wind speeds in order to achieve the same rated power output. Yaw angles of 20, 30, 40, 50 and 60 degrees are examined with the purpose of comparing structural loads and displacements between two control methods. The computed load effects reveal that the tower top and base shear forces are reduced significantly using the nacelle tilt control compared with the yaw control method. The shear forces and bending moments at the blade root also show favorable outcomes at most nacelle tilt angles except for 65 degrees.

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Yaw Systems for wind turbines – Overview of concepts, current challenges and design methods

Cited by 44 publications

References 10 publications

Dynamic Strategies for Yaw and Induction Control of Wind Farms Based on Large-Eddy Simulation and Optimization

Dynamic Strategies for Yaw and Induction Control of Wind Farms Based on Large-Eddy Simulation and Optimization

Robust active wake control in consideration of wind direction variability and uncertainty

Comparative study of yaw and nacelle tilt control strategies for a two-bladed downwind wind turbine

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