The fatigue loading effects of yaw control for wind plants

Zalkind, Daniel; Pao, Lucy Y.

doi:10.1109/acc.2016.7524969

Cited by 23 publications

(34 citation statements)

References 11 publications

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“…In contrast to what was reported 20 in previous studies, the fatigue load components do not necessarily decrease with increasing yaw offsets, and we offered justifications as to why that might be happening. Whereas blade-root loads can be said to decrease, large standard deviations of the mean results also point to caution and to the need to carefully assess the site conditions.…”

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confidence: 51%

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Assessment of Wind Turbine Component Loads Under Yaw-Offset Conditions

Damiani

Dana

Annoni

et al. 2017

Preprint

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Abstract. Renewed interest in yaw control for wind turbine and power plants for wake redirection and load mitigation demands a clear understanding of the effects of running with skewed inflow. In this paper, we investigate the physics of yawed operations, building up the complexity from a simplified analytical treatment to more complex aeroelastic simulations. Results in terms of damage equivalent loads (DELs) and extreme loads under operating, misaligned conditions are compared to data collected from an instrumented, utility-scale wind turbine. The analysis shows that multiple factors are responsible for the DELs of 5 the various components, and that airfoil aerodynamics, elastic characteristics of the rotor, and turbulence intensities are the primary drivers. Both fatigue and extreme loads are observed to have relatively complex trends with yaw offsets, which can change depending on the wind-speed regime. Good agreement is found between predicted and measured trends for both fatigue and ultimate loads.

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confidence: 51%

“…Zalkind and Pao (2016), for example, suggest the existence of an asymmetric behavior of blade and tower fatigue loads hinting at the same positive offset as load-favorable misalignment direction. …”

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confidence: 99%

Assessment of Wind Turbine Component Loads Under Yaw-Offset Conditions

Damiani

Dana

Annoni

et al. 2017

Preprint

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“…However, there are ongoing research campaigns which seek to understand and quantify the impacts to loading. Already published are studies which consider the impact on loads from operating in yaw using aero-servoelastic wind turbine models (Zalkind and Pao, 2016) and computational fluid dynamics (Schulz et al, 2016). Additionally, there is a currently ongoing field test in which a utility-scale wind turbine which is highly instrumented with load sensors is operated intentionally in yaw to assess impacts (Fleming et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

Field test of wake steering at an offshore wind farm

Fleming

Annoni

Shah³

et al. 2017

Wind Energ. Sci.

248

198

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Abstract. In this paper, a field test of wake-steering control is presented. The field test is the result of a collaboration between the National Renewable Energy Laboratory (NREL) and Envision Energy, a smart energy management company and turbine manufacturer. In the campaign, an array of turbines within an operating commercial offshore wind farm in China have the normal yaw controller modified to implement wake steering according to a yaw control strategy. The strategy was designed using NREL wind farm models, including a computational fluid dynamics model, Simulator fOr Wind Farm Applications (SOWFA), for understanding wake dynamics and an engineering model, FLOw Redirection and Induction in Steady State (FLORIS), for yaw control optimization. Results indicate that, within the certainty afforded by the data, the wake-steering controller was successful in increasing power capture, by amounts similar to those predicted from the models.

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“…The results indicate that the control is indeed capable of improving the power capture in the wind farm. In Zalkind [22], the increase of fatigue loads experienced by wind turbines using yaw control to redirect wakes is studied. In Urbàn [23], the focus is on the yaw control of the downstream wake-affected wind turbines for reducing the blade root flapwise fatigue loading: the main result is that modest wind turbine lifetime increases can be achieved for low wind speeds and high turbulence levels, but considerable improvements (up to the order of 20%) can be achieved when the wind speed is moderate and the turbulence intensity is low.…”

Section: Introductionmentioning

confidence: 99%

The Yawing Behavior of Horizontal-Axis Wind Turbines: A Numerical and Experimental Analysis

et al. 2019

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The yawing of horizontal-axis wind turbines (HAWT) is a major topic in the comprehension of the dynamical behavior of these kinds of devices. It is important for the study of mechanical loads to which wind turbines are subjected and it is important for the optimization of wind farms because the yaw active control can steer the wakes between nearby wind turbines. On these grounds, this work is devoted to the numerical and experimental analysis of the yawing behavior of a HAWT. The experimental tests have been performed at the wind tunnel of the University of Perugia on a three-bladed small HAWT prototype, having two meters of rotor diameter. Two numerical set ups have been selected: a proprietary code based on the Blade Element Momentum theory (BEM) and the aeroelastic simulation software FAST, developed at the National Renewable Energy Laboratory (NREL) in Golden, CO, USA. The behavior of the test wind turbine up to ±45 • of yaw offset is studied. The performances (power coefficient C P ) and the mechanical behavior (thrust coefficient C T ) are studied and the predictions of the numerical models are compared against the wind tunnel measurements. The results for C T inspire a subsequent study: its behavior as a function of the azimuth angle is studied and the periodic component equal to the blade passing frequency 3P is observed. The fluctuation intensity decreases with the yaw angle because the distance between tower and blade increases. Consequently, the tower interference is studied through the comparison of measurements and simulations as regards the fore-aft vibration spectrum and the force on top of the tower.

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The fatigue loading effects of yaw control for wind plants

Cited by 23 publications

References 11 publications

Assessment of Wind Turbine Component Loads Under Yaw-Offset Conditions

Assessment of Wind Turbine Component Loads Under Yaw-Offset Conditions

Field test of wake steering at an offshore wind farm

The Yawing Behavior of Horizontal-Axis Wind Turbines: A Numerical and Experimental Analysis

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