New European Wind Atlas: The Østerild balconies experiment

Karagali, Ioanna; Mann, Jakob; Dellwik, Ebba; Vasiljević, Nikola

doi:10.1088/1742-6596/1037/5/052029

Cited by 13 publications

(15 citation statements)

References 12 publications

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“…The aim of this experiment was to characterize the horizontal flow field above a flat, heterogeneous forested landscape at two heights relevant for wind energy applications. Known as the Østerild Balconies experiment (Mann et al, 2017;Karagali et al, 2018;Simon and Vasiljevic, 2018), the wind speed data covers a large horizontal area (around 50 km 2 ), with the possibility of characterizing flow patterns in a wide range of scales, both in time and space. However, these advantages come with increased complexity on data reliability.…”

Section: Real Data: øSterild Balconies Experimentsmentioning

confidence: 99%

“…The data used in this study originated from both phases of the experiment, with PPIs pointing to the west. For more details about the experiment, lidars and terrain characteristics see (Karagali et al, 2018;Vasiljevic et al, 2016;Simon and Vasiljevic, 2018).…”

Section: Real Data: øSterild Balconies Experimentsmentioning

confidence: 99%

“…Testing filters on a controlled and synthetic data set, contaminated with a well Table 1. Characteristics of the Balconies experiment, from Karagali et al (2018). The scans are not instantaneous neither totally synchronous, with a horizontal sweep speed of 2 • /s in the azimuth direction in a range of 90 • , with a total time of 45 s per scan.…”

Section: Synthetic Datamentioning

confidence: 99%

“…Such filters work by detecting discrete or anomalous steps in V LOS which present a difference between of line-of-sight wind speed, V LOS , and its local (moving) median above a certain threshold, predefined by the user. Beck and Kühn (2017) first and Karagali et al (2018) in an adapted version, follow a different approach (here called KDE filter, from Kernel Density Estimate) based on the statistical self-similarity of the data, which, in simple terms, assumes that reliable observations are alike and will be located close together in the observational space. The probability density distribution of observations (estimated via KDE) in a dynamically normalized V LOS − CNR space shows that measurements likely to be valid are located in a high density region.…”

Section: Introductionmentioning

confidence: 99%

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Filtering of pulsed lidars data using spatial information and a clustering algorithm

Alcayaga¹

2020

Preprint

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Abstract. Wind lidars present advantages over meteorological masts, including simultaneous multi-point observations, flexibility in measuring geometry, and reduced installation cost; but wind lidars come with the cost of increased complexity in terms of data quality and analysis. Carrier-to-noise ratio (CNR) has been the metric most commonly-used to recover reliable observations from lidar measurements, but with severely reduced data recovery. In this work we apply a clustering technique to identify unreliable measurements from pulsed lidars scanning a horizontal plane, taking advantage of all data available from the lidars–not only CNR, but also line-of-sight wind speed (VLOS), spatial position, and VLOS smoothness. The performance of this data filtering technique is evaluated in terms of data recovery and data quality, against both a median-like filter and a pure CNR-threshold filter. The results show that the clustering filter is capable of recovering more reliable data in noisy regions of the scans, increasing the data recovery up to 38 % and reducing by at least two thirds the acceptance of unreliable measurements, relative to the commonly used CNR-threshold. Along with this, the need for user intervention in the setup of data filtering is reduced considerably, which is a step towards a more automated and robust filter.

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Section: Real Data: øSterild Balconies Experimentsmentioning

confidence: 99%

Section: Real Data: øSterild Balconies Experimentsmentioning

confidence: 99%

Section: Synthetic Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Filtering of pulsed lidars data using spatial information and a clustering algorithm

Alcayaga¹

2020

Preprint

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“…In addition, the data availability of ground-based LiDARs in the PPI scan mode was the highest, generally above 95%. In the experiment performed at Østerild test station for large wind turbines in 2016 [107], Doppler LiDARs were installed on the balconies of light towers at 50 m and 200 m above the ground. Data obtained from horizontal scans at 50 m above the ground were categorized according to the inflow velocity measured from a sonic anemometer situated at 37 m above the ground.…”

Section: Wind Resource Assessmentmentioning

confidence: 99%

A Review of Progress and Applications of Pulsed Doppler Wind LiDARs

et al. 2019

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Doppler wind LiDAR (Light Detection And Ranging) makes use of the principle of optical Doppler shift between the reference and backscattered radiations to measure radial velocities at distances up to several kilometers above the ground. Such instruments promise some advantages, including its large scan volume, movability and provision of 3-dimensional wind measurements, as well as its relatively higher temporal and spatial resolution comparing with other measurement devices. In recent decades, Doppler LiDARs developed by scientific institutes and commercial companies have been well adopted in several real-life applications. Doppler LiDARs are installed in about a dozen airports to study aircraft-induced vortices and detect wind shears. In the wind energy industry, the Doppler LiDAR technique provides a promising alternative to in-situ techniques in wind energy assessment, turbine wake analysis and turbine control. Doppler LiDARs have also been applied in meteorological studies, such as observing boundary layers and tracking tropical cyclones. These applications demonstrate the capability of Doppler LiDARs for measuring backscatter coefficients and wind profiles. In addition, Doppler LiDAR measurements show considerable potential for validating and improving numerical models. It is expected that future development of the Doppler LiDAR technique and data processing algorithms will provide accurate measurements with high spatial and temporal resolutions under different environmental conditions.

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Characterization of atmospheric coherent structures and their impact on a utility-scale wind turbine

Abraham

Hong

2022

Flow

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Atmospheric turbulent velocity fluctuations are known to increase wind turbine structural loading and accelerate wake recovery, but the impact of vortical coherent structures in the atmosphere on wind turbines has not yet been evaluated. The current study uses flow imaging with natural snowfall with a field of view spanning the inflow and near wake. Vortical coherent structures with diameters of the order of 1 m are identified and characterized in the flow approaching a 2.5 MW wind turbine in the region spanning the bottom blade tip elevation to hub height. Their impact on turbine structural loading, power generation and wake behaviour are evaluated. Long coherent structure packets $(\mathrm{\ \mathbin{\lower.3ex\hbox{$\buildrel> \over {\smash{\scriptstyle\sim}\vphantom{_x}}$}}\ }200\;\textrm{m)}$ are shown to increase fluctuating stresses on the turbine support tower. Large inflow vortices interact with the turbine blades, leading to deviations from the expected power generation. The sign of these deviations is related to the rotation direction of the vortices, with rotation in the same direction as the circulation on the blades leading to periods of power surplus, and the opposite rotation causing power deficit. Periods of power deficit coincide with wake contraction events. These findings highlight the importance of considering coherent structure properties when making turbine design and siting decisions.

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New European Wind Atlas: The Østerild balconies experiment

Cited by 13 publications

References 12 publications

Filtering of pulsed lidars data using spatial information and a clustering algorithm

Filtering of pulsed lidars data using spatial information and a clustering algorithm

A Review of Progress and Applications of Pulsed Doppler Wind LiDARs

Characterization of atmospheric coherent structures and their impact on a utility-scale wind turbine

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