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Thunderstorm downburst risks to wind farms
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10.1063/1.4792497
/content/aip/journal/jrse/5/1/10.1063/1.4792497
http://aip.metastore.ingenta.com/content/aip/journal/jrse/5/1/10.1063/1.4792497

Figures

Image of FIG. 1.
FIG. 1.

Illustration of wind field in a vertical plane through the downburst center. a) Vertical, Uz , and radial, Ur , components from Eqs. (1) and (2) , (b) downburst winds, and (c) downburst and ambient winds.

Image of FIG. 2.
FIG. 2.

Wind field in a vertical plane through the downburst center at its peak intensity. The expanded views show two 2-D square regions of contrasting wind fields.

Image of FIG. 3.
FIG. 3.

Plan view showing turbines in the wind farm and the path of a moving downburst.

Image of FIG. 4.
FIG. 4.

Pitch control, rotor speed, and power curve.

Image of FIG. 5.
FIG. 5.

Integrated damage or loss assessment for turbine units in a wind farm during simulated downbursts.

Image of FIG. 6.
FIG. 6.

Simulation of an illustrative JAWS “average” downburst. Note that d(t) = distance from downburst to turbine; rm (t) = radius to maximum winds; Unorm  = wind speed normal to the rotor plane (at hub); Pitch Angle = blade pitch angle; FlapBM = flapwise bending moment at a blade root. (a) Plan view showing downburst track and turbine, (b) Uamb = 6 m/s; with yaw control.

Image of FIG. 7.
FIG. 7.

Distribution of array-average hub-height extreme wind speed and extreme flapwise bending moment at a blade root, accounting for uncertainty in downburst touchdown location and direction of translation. (a) Distribution of the array-average hub-height extreme wind based on 10 240 simulations for the JAWS average downburst. (b) Distribution of the array-average extreme flapwise bending moment at a blade root based on 10 240 simulations for the JAWS average downburst. (c) Distribution of the array-average hub-height extreme wind based on 10 240 simulations for the NIMROD Yorkville downburst. (d) Distribution of the array-average extreme flapwise bending moment at a blade root based on 10 240 simulations for the NIMROD Yorkville downburst.

Image of FIG. 8.
FIG. 8.

The worst case out of 10 240 simulations for the JAWS average downburst (where R 0 = 5.3 km, θ0 = 144.5°, and °) that resulted in the largest array-average extreme load (Utrans  = downburst translational speed;  = ambient wind speed at 90 m; HorWndV = horizontal wind speed at hub height; HorWndDir = horizontal wind direction at hub height; Yaw = yaw position of turbine nacelle; FlapBM1 = flapwise bending moment at root of Blade 1 (similar variables for Blades 2 and 3); Pitch = blade pitch angle). (a) Downburst track and extreme flapwise bending moment at a blade root due to non-turbulent wind field. (b) Hub-height wind speed, nacelle yaw, blade pitch angle, and flapwise bending moment at blade root of turbine #17 (see (a)).

Image of FIG. 9.
FIG. 9.

The worst case out of 10 240 simulations for the NIMROD Yorkville downburst (where R 0 = 10.7 km, θ0 = 185.5°, and °) that resulted in the largest array-average extreme load (Utrans  = downburst translational speed; Uamb (90 m) = ambient wind speed at 90 m; HorWndV = horizontal wind speed at hub height; HorWndDir = horizontal wind direction at hub height; Yaw = yaw position of turbine nacelle; FlapBM1 = flapwise bending moment at root of Blade 1 (similar variables for Blades 2 and 3); Pitch = blade pitch angle). (a) Downburst track and extreme flapwise bending moment at a blade root due to non-turbulent wind field. (b) Hub-height wind speed, nacelle yaw, blade pitch angle, and flapwise bending moment at blade root of turbine #8 (see (a)).

Image of FIG. 10.
FIG. 10.

Wind field and turbine loads for a NIMROD Yorkville downburst simulation (where R 0 = 7.4 km, θ0 = 172.6°, and °) that resulted in the largest loads at a single turbine unit (Utrans  = downburst translational speed;  = ambient wind speed at 90 m; HorWndV = horizontal wind speed at hub height; HorWndDir = horizontal wind direction at hub height; Yaw = yaw position of turbine nacelle; FlapBM1 = flapwise bending moment at root of Blade 1 (similar variables for Blades 2 and 3); Pitch = blade pitch angle). (a) Downburst track and extreme flapwise bending moment at a blade root due to both non-turbulent and turbulent parts of the wind field. (b) Hub-height wind speed, nacelle yaw, blade pitch angle, and flapwise bending moment at blade root of turbine #16 (see (a)).

Image of FIG. 11.
FIG. 11.

Histograms of array-average hub-height extreme wind speed and extreme flapwise bending moment at a blade root, accounting for uncertainty in downburst touchdown location and direction of translation. (a) Histogram of the array-average hubheight extreme wind based on 2490 “significant” simulations for the JAWS average downburst. (b) Histogram of the array-average extreme flapwise bending moment at a blade root based on 2490 “significant” simulations for the JAWS average downburst. (c) Histogram of the array-average hub-height extreme wind based on 2689 “significant” simulations for the NIMROD Yorkville downburst. (d) Histogram of the array-average extreme flapwise bending moment at a blade root based on 2689 “significant” simulations for the NIMROD Yorkville downburst.

Image of FIG. 12.
FIG. 12.

Conditional probability of exceedance plots for array-average hub-height extreme wind speed and extreme flapwise bending moment at a blade root, accounting for uncertainty in downburst touchdown location and direction of translation. (a) Conditional probability of exceedance for the array-average hub-height extreme wind based on 2490 “significant” simulations for the JAWS average downburst. (b) Conditional probability of exceedance for the array-average extreme flapwise bending moment as a blade root based on 2490 “significant” simulations for the JAWS average downburst. (c) Conditional probability of exceedance for the array-average hub-height extreme wind based on 2689 “significant” simulations for the NIMROD Yorkville downburst. (d) Conditional probability of exceedance for the array-average extreme flapwise bending moment as a blade root based on 2689 “significant” simulations for the NIMROD Yorkville downburst.

Tables

Generic image for table
Table I.

Thunderstorm downburst parameters used in the simulations.

Generic image for table
Table II.

Turbine properties/dimensions and schematic diagram.

Generic image for table
Table III.

Lower and upper bounds for uniformly distributed random variables used to describe downburst touchdown locations and translation directions. The upper bound for R 0 is taken, for consistency, to be the larger of the R 0, max values for the two downbursts.

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/content/aip/journal/jrse/5/1/10.1063/1.4792497
2013-02-19
2014-04-23
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Thunderstorm downburst risks to wind farms
http://aip.metastore.ingenta.com/content/aip/journal/jrse/5/1/10.1063/1.4792497
10.1063/1.4792497
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