Atmospheric stability affects wind turbine power collection

Wharton, Sonia; Lundquist, Julie K.

doi:10.1088/1748-9326/7/1/014005

Cited by 206 publications

(188 citation statements)

References 15 publications

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“…This wind-speed impact is lofted by vigorous convective plumes, with significant differences extending up to 500 m. Meanwhile, when the boundary layer is very stable, the roughness effect is confined to a small layer within the first 20 m above the surface (Mahrt 1999). These results illustrate the importance of boundary-layer stability to crop-turbine interactions, which is comparable to the observed influence of stability on windturbine performance (Wharton and Lundquist 2012;Vanderwende and Lundquist 2012). Also provided is the number of times each stability class was simulated by the model at the wind farm…”

Section: Effects Of Crop Selection On the Local Wind Profilesupporting

confidence: 63%

Could Crop Height Affect the Wind Resource at Agriculturally Productive Wind Farm Sites?

Vanderwende

Lundquist

2015

Boundary-Layer Meteorol

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The collocation of cropland and wind turbines in the US Midwest region introduces complex meteorological interactions that could influence both agriculture and wind-power production. Crop management practices may affect the wind resource through alterations of land-surface properties. We use the weather research and forecasting (WRF) model to estimate the impact of crop height variations on the wind resource in the presence of a large turbine array. A hypothetical wind farm consisting of 121 1.8-MW turbines is represented using the WRF model wind-farm parametrization. We represent the impact of selecting soybeans rather than maize by altering the aerodynamic roughness length in a region approximately 65 times larger than that occupied by the turbine array. Roughness lengths of 0.1 and 0.25 m represent the mature soy crop and a mature maize crop, respectively. In all but the most stable atmospheric conditions, statistically significant hub-height wind-speed increases and rotor-layer wind-shear reductions result from switching from maize to soybeans. Based on simulations for the entire month of August 2013, wind-farm energy output increases by 14 %, which would yield a significant monetary gain. Further investigation is required to determine the optimal size, shape, and crop height of the roughness modification to maximize the economic benefit and minimize the cost of such crop-management practices. These considerations must be balanced by other influences on crop choice such as soil requirements and commodity prices.

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Section: Effects Of Crop Selection On the Local Wind Profilesupporting

confidence: 63%

Could Crop Height Affect the Wind Resource at Agriculturally Productive Wind Farm Sites?

Vanderwende

Lundquist

2015

Boundary-Layer Meteorol

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“…In particular, lidar-measured turbulence is a significant parameter in the wind energy industry, where high-resolution measurements are often needed in remote locations. Wind power production can differ substantially as a result of turbulence (e.g., Wharton and Lundquist, 2012;Clifton and Wagner, 2014), and turbulence can induce damaging loads on the turbine blades, reducing the turbine's reliability and expected lifetime (e.g., Kelley et al, 2006). Thus, turbulence is an extremely important parameter to measure in the wind farm site selection and design process.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of three lidar scanning strategies for turbulence measurements

et al. 2016

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Abstract.Several errors occur when a traditional Doppler beam swinging (DBS) or velocity-azimuth display (VAD) strategy is used to measure turbulence with a lidar. To mitigate some of these errors, a scanning strategy was recently developed which employs six beam positions to independently estimate the u, v, and w velocity variances and covariances. In order to assess the ability of these different scanning techniques to measure turbulence, a Halo scanning lidar, WindCube v2 pulsed lidar, and ZephIR continuous wave lidar were deployed at field sites in Oklahoma and Colorado with collocated sonic anemometers.Results indicate that the six-beam strategy mitigates some of the errors caused by VAD and DBS scans, but the strategy is strongly affected by errors in the variance measured at the different beam positions. The ZephIR and WindCube lidars overestimated horizontal variance values by over 60 % under unstable conditions as a result of variance contamination, where additional variance components contaminate the true value of the variance. A correction method was developed for the WindCube lidar that uses variance calculated from the vertical beam position to reduce variance contamination in the u and v variance components. The correction method reduced WindCube variance estimates by over 20 % at both the Oklahoma and Colorado sites under unstable conditions, when variance contamination is largest. This correction method can be easily applied to other lidars that contain a vertical beam position and is a promising method for accurately estimating turbulence with commercially available lidars.

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“…Few studies have been able to capture information about the two-and three-dimensional flow fields of wind speed, direction, and turbulence, as well as how these atmospheric variables affect fatigue loads (e.g., stress on the blades) and turbine thrust coefficients. In Wharton and Lundquist (2012b) we examined the influences of ambient turbulence and wind shear on power production in the leading row of turbines at the same wind farm as discussed here.…”

Section: Discussionmentioning

confidence: 99%

“…We also focused on spring and summer time periods because earlier work (Wharton and Lundquist 2012a) found that stability effects on the wind speed profile and turbulence profile were strongest during these time periods. Wharton and Lundquist (2012b) furthermore found strong stability effects on power generation during these months at the upwind row of turbines.…”

mentioning

confidence: 91%