Automated wind turbine wake characterization in complex terrain
<p>An automated wind turbine wake characterization algorithm has been developed and applied to a data set of over 19 000 scans measured by a ground-based scanning Doppler lidar at Perdigão, Portugal, over the period January to June 2017. Potential wake cases are identified by wind s...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-06-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://www.atmos-meas-tech.net/12/3463/2019/amt-12-3463-2019.pdf |
| Summary: | <p>An automated wind turbine wake characterization algorithm has been developed
and applied to a data set of over 19 000 scans measured by a ground-based
scanning Doppler lidar at Perdigão, Portugal, over the period January to
June 2017. Potential wake cases are identified by wind speed, direction and
availability of a retrieved free-stream wind speed. The algorithm correctly
identifies the wake centre position in 62 % of possible wake cases, with 46 %
having a clear and well-defined wake centre surrounded by a coherent area of
lower wind speeds while 16 % have split centres or multiple lobes where
the lower wind speed volumes are no longer in coherent areas but present as
two or more distinct areas or lobes. Only 5 % of cases are not detected;
the remaining 33 % could not be categorized either by the algorithm or
subjectively, mainly due to the complexity of the background flow. Average
wake centre heights categorized by inflow wind speeds are shown to be
initially lofted (to two rotor diameters, <span class="inline-formula"><i>D</i></span>, downstream) except when the inflow
wind speeds exceed 12 ms<span class="inline-formula"><sup>−1</sup></span>. Even under low wind speeds, by 3.5 <span class="inline-formula"><i>D</i></span>
downstream of the wind turbine, the mean wake centre position is below the
initial wind turbine hub height and descends broadly following the terrain
slope. However, this behaviour is strongly linked to the hour of the day and
atmospheric stability. Overnight and in stable conditions, the average
height of the wake centre is 10 m higher than in unstable conditions at 2 <span class="inline-formula"><i>D</i></span> downstream from the wind turbine and 17 m higher at 4.5 <span class="inline-formula"><i>D</i></span> downstream.</p> |
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| ISSN: | 1867-1381 1867-8548 |