Turbulence-Turbine Interaction: The Basis for the Development of the TurbSim Stochastic Simulator

Kelley, Neil

doi:10.2172/1031981

Cited by 31 publications

(35 citation statements)

References 23 publications

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“…While LLJs often greatly increase the speed of the wind in the rotor layer of a turbine (40-120 m above the ground in this study), shear and veer place additional stresses on the structure that can increase the need for regular maintenance and the possibility of mechanical failure (Eggers et al 2003;Kelley 2011). Correlation of wind speeds over large distances can also cause problems for balancing supply and demand on the energy grid if large amounts of wind-generated electricity dominate the system.…”

Section: Introductionmentioning

confidence: 89%

“…Veer was also elevated during strong jet periods, though such values were consistent with nonjet stable periods. The high rotor-layer shear (;3.5 m s 21 ) and veer (;78) values present during strong jet episodes produce forces on turbine structures that can impact long-term mechanical reliability (Kelley 2011). While the V1 lidar cannot directly measure turbulence, we can estimate wind variability by taking the standard deviation of 1-Hz measurements for each 3-min averaging period.…”

Section: B the Impact Of Observed Jets On Rotor-layer Windsmentioning

confidence: 99%

“…1999; Moriarty et al 2004;Kelley 2011;Churchfield et al 2012). Finally, rapid increases or decreases of wind speeds in the rotor-layer have been connected to low-level jets in modeling studies (Deppe et al 2013).…”

Section: B the Impact Of Observed Jets On Rotor-layer Windsmentioning

confidence: 99%

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Observing and Simulating the Summertime Low-Level Jet in Central Iowa

Vanderwende

Lundquist

Rhodes

et al. 2015

Monthly Weather Review

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In the U.S. state of Iowa, the increase in wind power production has motivated interest into the impacts of low-level jets on turbine performance. In this study, two commercial lidar systems were used to sample wind profiles in August 2013. Jets were systematically detected and assigned an intensity rating from 0 (weak) to 3 (strong). Many similarities were found between observed jets and the well-studied Great Plains low-level jet in summer, including average jet heights between 300 and 500 m above ground level, a preference for southerly wind directions, and a nighttime bias for stronger jets. Strong vertical wind shear and veer were observed, as well as veering over time associated with the LLJs. Speed, shear, and veer increases extended into the turbine-rotor layer during intense jets. Ramp events, in which winds rapidly increase or decrease in the rotor layer, were also commonly observed during jet formation periods. The lidar data were also used to evaluate various configurations of the Weather Research and Forecasting Model. Jet occurrence exhibited a stronger dependence on the choice of initial and boundary condition data, while reproduction of the strongest jets was influenced more strongly by the choice of planetary boundary layer scheme. A decomposition of mean model winds suggested that the main forcing mechanism for observed jets was the inertial oscillation. These results have implications for wind energy forecasting and site assessment in the Midwest.

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Section: Introductionmentioning

confidence: 89%

Section: B the Impact Of Observed Jets On Rotor-layer Windsmentioning

confidence: 99%

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Observing and Simulating the Summertime Low-Level Jet in Central Iowa

Vanderwende

Lundquist

Rhodes

et al. 2015

Monthly Weather Review

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“…They found that LLJs can cause instabilities leading to coherent turbulence and KelvinHelmholtz waves, which they correlated with an increase in flapwise loads in the blade roots. In a following study, Kelley (2011) detected that the maximum turbine damages occurred within a narrow range of atmospheric stability usually associated with LLJs. Sathe et al (2013) used wind profile models together with an aeroelastic simulator to investigate whether the wind profile and the atmospheric stability modify the wind turbine loads.…”

Section: Previous Work On Wind Shearmentioning

confidence: 96%

Impacts of the low-level jet's negative wind shear on the wind turbine

et al. 2017

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Abstract.Nocturnal low-level jets (LLJs) are defined as relative maxima in the vertical profile of the horizontal wind speed at the top of the stable boundary layer. Such peaks constitute major power resources for wind turbines. However, a wind speed maximum implies a transition from positive wind shears below the peak to negative ones above. The effect that such a transition has on wind turbines has not been thoroughly studied.This research study employed a methodical approach to the study of negative wind shear's impacts on wind turbines. Up to now, the presence of negative shears inside the turbine's rotor in relation to the presence of positive shears has been largely ignored. A parameter has been proposed to quantify that presence in future studies of LLJ-wind-turbine interactions. Simulations were performed using the NREL aeroelastic simulator FAST code. Rather than using synthetic profiles to generate the wind data, all simulations were based on real data captured at the high frequency of 50 Hz, which allowed us to perform the analysis of a turbine's impacts with real-life, small scales of wind motions.It was found that the presence of negative wind shears at the height of the turbine's rotor appeared to exert a positive impact on reducing the motions of the nacelle and the tower in every direction, with oscillations reaching a minimum when negative shears covered the turbine swept area completely. Only the tower wobbling in the spanwise direction was amplified by the negative shears; however, this occurred at the tower's slower velocities and accelerations. The forces and moments were also reduced by the negative shears. The aforementioned impacts were less beneficial in the rotating parts, such as the blades and the shafts. Finally, the variance in power production was also reduced. These findings can be very important for the next generation of wind turbines as they reach deeper into LLJ's typical heights.The study demonstrated that the presence of negative shears is significant in reducing the loading on wind turbines. A major conclusion of this study is that the wind turbines of the future should probably be designed with the aim of reaching the top of the nightly boundary layer more often and therefore the altitudes where negative shears are more frequent. Doing so will help to reduce the positive shear's associated damage and to capture the significant LLJ energy.

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“…Given that the finest domain uses a 1.25-km resolution, turbulence is not resolved by the model grid but rather estimated by the MYNN PBL scheme. Despite this potential source of error, any changes to TKE production are important, as turbulence can affect turbine power output and increase stresses on the turbine structure (e.g., Eggers et al 2003;Kelley 2011).…”

Section: Effects Of Crop Selection On the Local Wind Profilementioning

confidence: 99%

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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Turbulence-Turbine Interaction: The Basis for the Development of the TurbSim Stochastic Simulator

Cited by 31 publications

References 23 publications

Observing and Simulating the Summertime Low-Level Jet in Central Iowa

Observing and Simulating the Summertime Low-Level Jet in Central Iowa

Impacts of the low-level jet's negative wind shear on the wind turbine

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

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