Characterizing wind gusts in complex terrain

Abstract. Wind gusts are a key driver of aerodynamic loading, especially for tall structures such a bridges and wind turbines. However, gust characteristics in complex terrain are not well understood and common approximations used to describe wind gust behavior may not be appropriate at heights relevant to wind turbines and other structures. Data collected in the Perdigão experiment are analyzed herein to provide a foundation for improved wind gust characterization and process-level understanding of flow intermittency in complex terrain. High-resolution observations from sonic anemometers and vertically pointing Doppler lidars are used to conduct a detailed study of gust characteristics with a specific focus on the parent distributions of nine gust parameters (that describe velocity, time, and length scales), their joint distributions, height variation, and coherence in the vertical and horizontal planes. Best-fit distributional forms for varying gust properties show good agreement with those from previous experiments in moderately complex terrain but generate nonconservative estimates of the gust properties that are of key importance to structural loading. Probability distributions of gust magnitude derived from vertically pointing Doppler lidars exhibit good agreement with estimates from sonic anemometers despite differences arising from volumetric averaging and the terrain complexity. Wind speed coherence functions during gusty periods (which are important to structural wind loading) are similar to less complex sites for small vertical displacements (10 to 40 m), but do not exhibit an exponential form for larger horizontal displacements (800 to 1500 m).

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Characterizing Wind Gusts in Complex Terrain

10.5194/acp-2018-906 ◽

2018 ◽

Author(s):

Frederick Letson ◽

Rebecca J. Barthelmie ◽

Weifei Hu ◽

Sara C. Pryor

Keyword(s):

Wind Turbines ◽

Complex Terrain ◽

Probability Distributions ◽

Wind Loading ◽

Wind Gust ◽

Wind Gusts ◽

Sonic Anemometers ◽

Vertical Displacements ◽

Structural Loading ◽

Good Agreement

Abstract. Wind gusts are a key driver of aerodynamic loading, especially for tall structures such a bridges and wind turbines. However, gust characteristics in complex terrain are not well understood and common approximations used to describe wind gust behavior may not be appropriate at heights relevant to wind turbines and other structures. Data collected in the Perdigão experiment are analyzed herein to provide a foundation for improved wind gust characterization and process-level understanding of flow intermittency in complex terrain. High-resolution observations from sonic anemometers and vertically pointing Doppler lidars are used to conduct a detailed study of gust characteristics with a specific focus on the parent distributions of nine gust parameters (that describe velocity, time and length scales), their joint distributions, height variation and coherence in the vertical and horizontal planes. Best-fit distributional forms for varying gust properties show good agreement with those from previous experiments in moderately complex terrain but generate non-conservative estimates of the gust properties that are of key importance to structural loading. Probability distributions of gust magnitude derived from vertical pointing Doppler lidars exhibit good agreement with estimates from sonic anemometers despite differences arising from volumetric averaging and the terrain complexity. Wind speed coherence functions during gusty periods (which are important to structural wind loading) are similar to less complex sites for small vertical displacements (10 to 40 m), but do not exhibit an exponential form for larger horizontal displacements (800 to 1500 m).

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Wind Gust Characterization at Wind Turbine Relevant Heights in Moderately Complex Terrain

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-18-0040.1 ◽

2018 ◽

Vol 57 (7) ◽

pp. 1459-1476 ◽

Cited By ~ 6

Author(s):

W. Hu ◽

F. Letson ◽

R. J. Barthelmie ◽

S. C. Pryor

Keyword(s):

Complex Terrain ◽

Power Spectra ◽

Wind Component ◽

Length Scale ◽

Wind Gust ◽

Atmospheric Conditions ◽

Length Scales ◽

Wind Gusts ◽

Sonic Anemometers ◽

Gust Factors

AbstractImproved understanding of wind gusts in complex terrain is critically important to wind engineering and specifically the wind energy industry. Observational data from 3D sonic anemometers deployed at 3 and 65 m at a site in moderately complex terrain within the northeastern United States are used to calculate 10 descriptors of wind gusts and to determine the parent distributions that best describe these parameters. It is shown that the parent distributions exhibit consistency across different descriptors of the gust climate. Specifically, the parameters that describe the gust intensity (gust amplitude, rise magnitude, and lapse magnitude; i.e., properties that have units of length per time) fit the two-parameter Weibull distribution, those that are unitless ratios (gust factor and peak factor) are described by log-logistic distributions, and all other properties (peak gust, rise and lapse times, gust asymmetric factor, and gust length scale) are lognormally distributed. It is also shown that gust factors scale with turbulence intensity, but gusts are distinguishable in power spectra of the longitudinal wind component (i.e., they have demonstrably different length scales than the average eddy length scale). Gust periods at the lower measurement height (3 m) are consistent with shear production, whereas at 65 m they are not. At this site, there is only a weak directional dependence of gust properties on site terrain and land cover variability along sectorial transects, but large gust length scales and gust factors are more likely to be observed in unstable atmospheric conditions.

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Improvement Dependability of Offshore Horizontal-Axis Wind Turbines by Applying New Mathematical Methods for Calculation the Excess Speed in Case of Wind Gusts

Energies ◽

10.3390/en14113085 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3085

Author(s):

Konstantin Osintsev ◽

Seregei Aliukov ◽

Alexander Shishkov

Keyword(s):

Computer Simulation ◽

Wind Turbines ◽

Experimental Studies ◽

Offshore Wind ◽

Approximation Schemes ◽

Calculation Error ◽

Strong Wind ◽

Mathematical Methods ◽

Wind Gusts ◽

Gas Dynamic

The problem of increasing the reliability of wind turbines exists in the development of new offshore oil and natural gas fields. Reducing emergency situations is necessary due to the autonomous operation of drilling rigs and bulk seaports in the subarctic and Arctic climate. The relevance of the topic is linked with the development of a methodology for theoretical and practical studies of gas dynamics when gas flows in a pipe, based on a mathematical model using new mathematical methods for calculation of excess speeds in case of wind gusts. Problems in the operation of offshore wind turbines arise with storm gusts of wind, which is comparable to the wave movement of the gas flow. Thus, the scientific problem of increasing the reliability of wind turbines in conditions of strong wind gusts is solved. The authors indicate a gross error in the calculations when approximating through the use of the Fourier series. The obtained results will allow us to solve one of the essential problems of modeling at this stage of its development, namely: to reduce the calculation time and the adequacy of the model built for similar installations and devices. Experimental studies of gas-dynamic flows are carried out on the example of a physical model of a wind turbine. In addition, a computer simulation of the gas-dynamic flow process was carried out. The use of new approximation schemes in processing the results of experiments and computer simulation can reduce the calculation error by 1.2 percent.

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Wind Gust Detection and Impact Prediction for Wind Turbines

Remote Sensing ◽

10.3390/rs10040514 ◽

2018 ◽

Vol 10 (4) ◽

pp. 514 ◽

Cited By ~ 5

Author(s):

Kai Zhou ◽

Nihanth Cherukuru ◽

Xiaoyu Sun ◽

Ronald Calhoun

Keyword(s):

Wind Turbines ◽

Wind Gust ◽

Impact Prediction

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Comparison of Spar and Semisubmersible Floater Concepts of Offshore Wind Turbines Using Long-Term Analysis

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.4031312 ◽

2015 ◽

Vol 137 (6) ◽

Cited By ~ 6

Author(s):

Hasan Bagbanci ◽

D. Karmakar ◽

C. Guedes Soares

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Transfer Functions ◽

Probability Distributions ◽

Offshore Wind ◽

Short Term ◽

Offshore Wind Turbines ◽

Floating Wind Turbine ◽

Offshore Floating Wind Turbine

The long-term probability distributions of a spar-type and a semisubmersible-type offshore floating wind turbine response are calculated for surge, heave, and pitch motions along with the side-to-side, fore–aft, and yaw tower base bending moments. The transfer functions for surge, heave, and pitch motions for both spar-type and semisubmersible-type floaters are obtained using the fast code and the results are also compared with the results obtained in an experimental study. The long-term predictions of the most probable maximum values of motion amplitudes are used for design purposes, so as to guarantee the safety of the floating wind turbines against overturning in high waves and wind speed. The long-term distribution is carried out using North Atlantic wave data and the short-term floating wind turbine responses are represented using Rayleigh distributions. The transfer functions are used in the procedure to calculate the variances of the short-term responses. The results obtained for both spar-type and semisubmersible-type offshore floating wind turbine are compared, and the study will be helpful in the assessments of the long-term availability and economic performance of the spar-type and semisubmersible-type offshore floating wind turbine.

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Wind Estimation in the Lower Atmosphere Using Multirotor Aircraft

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-16-0177.1 ◽

2017 ◽

Vol 34 (5) ◽

pp. 1183-1191 ◽

Cited By ~ 52

Author(s):

Ross T. Palomaki ◽

Nathan T. Rose ◽

Michael van den Bossche ◽

Thomas J. Sherman ◽

Stephan F. J. De Wekker

Keyword(s):

Wind Speed ◽

Sonic Anemometer ◽

Unmanned Aircraft ◽

Lower Atmosphere ◽

Promising Alternative ◽

Atmospheric Structure ◽

Structure And Dynamics ◽

Sonic Anemometers ◽

Vertical Profiling ◽

Good Agreement

AbstractUnmanned aerial vehicles are increasingly used to study atmospheric structure and dynamics. While much emphasis has been on the development of fixed-wing unmanned aircraft for atmospheric investigations, the use of multirotor aircraft is relatively unexplored, especially for capturing atmospheric winds. The purpose of this article is to demonstrate the efficacy of estimating wind speed and direction with 1) a direct approach using a sonic anemometer mounted on top of a hexacopter and 2) an indirect approach using attitude data from a quadcopter. The data are collected by the multirotor aircraft hovering 10 m above ground adjacent to one or more sonic anemometers. Wind speed and direction show good agreement with sonic anemometer measurements in the initial experiments. Typical errors in wind speed and direction are smaller than 0.5 and 30°, respectively. Multirotor aircraft provide a promising alternative to traditional platforms for vertical profiling in the atmospheric boundary layer, especially in conditions where a tethered balloon system is typically deployed.

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Wind Gust Measuring at Low Altitude Using An Unmanned Aerial System

10.32920/ryerson.14653290 ◽

2021 ◽

Author(s):

Alton Yeung

Keyword(s):

Turbulence Models ◽

Satellite System ◽

Data System ◽

Measurement Unit ◽

Wind Gust ◽

Wind Gusts ◽

Low Altitude ◽

And Performance ◽

Global Navigation Satellite ◽

Aerial Platform

A small unmanned aerial vehicle (UAV) was developed with the specific objective to explore atmospheric wind gusts at low altitudes within the atmospheric boundary layer (ABL). These gusts have major impacts on the flight characteristics and performance of modern small unmanned aerial vehicles. Hence, this project was set to investigate the power spectral density of gusts observed at low altitudes by measuring the gusts with an aerial platform. The small UAV carried an air-data system including a fivehole probe that was adapted for this specific application. The air-data system measured the local wind gusts with an accuracy of 0.5 m/s by combining inputs from a five-hole probe, an inertial measurement unit, and Global Navigation Satellite System (GNSS) receivers. Over 20 flights were performed during the development of the aerial platform. Airborne experiments were performed to collect gust data at low altitudes between 50 m and 100 m. The result was processed into turbulence spectrum and the measurements were compared with the MIL-HDBK-1797 von K´arm´an turbulence model and the results have shown the model underpredicted the gust intensities experienced by the flight vehicle. The anisotropic properties of low-altitude turbulence were also observed when analyzing the measured gusts spectra. The wind and gust data collected are useful for verifying the existing turbulence models for low-altitude flights and benefit the future development of small UAVs in windy environment.

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Prognostics-based adaptive control strategy for lifetime control of wind turbines

10.5194/wes-2021-144 ◽

2021 ◽

Author(s):

Edwin Kipchirchir ◽

Manh Hung Do ◽

Jackson Githu Njiri ◽

Dirk Söffker

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Control Strategy ◽

Fatigue Loading ◽

Operational Reliability ◽

Operating Conditions ◽

Rotor Blades ◽

Time Step ◽

Damage Level ◽

Structural Loading

Abstract. Variability of wind profiles in both space and time is responsible for fatigue loading in wind turbine components. Advanced control methods for mitigating structural loading in these components have been proposed in previous works. These also incorporate other objectives like speed and power regulation for above-rated wind speed operation. In recent years, lifetime control and extension strategies have been proposed to guaranty power supply and operational reliability of wind turbines. These control strategies typically rely on a fatigue load evaluation criteria to determine the consumed lifetime of these components, subsequently varying the control set-point to guaranty a desired lifetime of the components. Most of these methods focus on controlling the lifetime of specific structural components of a wind turbine, typically the rotor blade or tower. Additionally, controllers are often designed to be valid about specific operating points, hence exhibit deteriorating performance in varying operating conditions. Therefore, they are not able to guaranty a desired lifetime in varying wind conditions. In this paper an adaptive lifetime control strategy is proposed for controlled ageing of rotor blades to guaranty a desired lifetime, while considering damage accumulation level in the tower. The method relies on an online structural health monitoring system to vary the lifetime controller gains based on a State of Health (SoH) measure by considering the desired lifetime at every time-step. For demonstration, a 1.5 MW National Renewable Energy Laboratory (NREL) reference wind turbine is used. The proposed adaptive lifetime controller regulates structural loading in the rotor blades to guaranty a predefined damage level at the desired lifetime without sacrificing on the speed regulation performance of the wind turbine. Additionally, significant reduction in the tower fatigue damage is observed.

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