Characterization of wind velocities in the upstream induction zone of a wind turbine using scanning continuous-wave lidars

Simley, Eric; Angelou, Nikolas; Mikkelsen, Torben; Sjöholm, Mikael; Mann, Jakob; Pao, Lucy Y.

doi:10.1063/1.4940025

Cited by 99 publications

(95 citation statements)

References 14 publications

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“…Three-dimensional wind-field measurements made using dual-Doppler intersecting RHI scans and using continuity to estimate the vertical velocity were used to study flow upstream and downstream of a utility-scale wind turbine . Three-dimensional wind and turbulence measurements using fully coordinated short-range continuous wave triple lidars (Mikkelsen et al, 2008;Simley et al, 2016) and long-range triple lidar scanning Vasiljević et al, 2016) have been demonstrated to provide high quality measurements of complex flow. In addition, manually coordinated triple lidar measurements (Wang et al, 2016) were also tested and showed promise in measuring the 3-D wind fields operationally.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of single and multiple Doppler lidar techniques to measure complex flow during the XPIA field campaign

et al. 2017

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Abstract. Accurate three-dimensional information of wind flow fields can be an important tool in not only visualizing complex flow but also understanding the underlying physical processes and improving flow modeling. However, a thorough analysis of the measurement uncertainties is required to properly interpret results. The XPIA (eXperimental Planetary boundary layer Instrumentation Assessment) field campaign conducted at the Boulder Atmospheric Observatory (BAO) in Erie, CO, from 2 March to 31 May 2015 brought together a large suite of in situ and remote sensing measurement platforms to evaluate complex flow measurement strategies.In this paper, measurement uncertainties for different single and multi-Doppler strategies using simple scan geometries (conical, vertical plane and staring) are investigated. The tradeoffs (such as time-space resolution vs. spatial coverage) among the different measurement techniques are evaluated using co-located measurements made near the BAO tower. Sensitivity of the single-/multi-Doppler measurement uncertainties to averaging period are investigated using the sonic anemometers installed on the BAO tower as the standard reference. Finally, the radiometer measurements are used to partition the measurement periods as a function of atmospheric stability to determine their effect on measurement uncertainty.It was found that with an increase in spatial coverage and measurement complexity, the uncertainty in the wind measurement also increased. For multi-Doppler techniques, the increase in uncertainty for temporally uncoordinated measurements is possibly due to requiring additional assumptions of stationarity along with horizontal homogeneity and less representative line-of-sight velocity statistics. It was also found that wind speed measurement uncertainty was lower during stable conditions compared to unstable conditions.

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Section: Introductionmentioning

confidence: 99%

Evaluation of single and multiple Doppler lidar techniques to measure complex flow during the XPIA field campaign

et al. 2017

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“…Branlard et al (2016) emphasize that further investigations are necessary to conclude whether the effects of the stagnation on the turbulence are systematic or not (see also Branlard, 2017, which is an expanded version of Branlard's thesis). Simley et al (2016) measure the turbulent inflow towards a Vestas V27 wind turbine using three synchronized continuous wave, scanning Doppler lidars. They clearly see the stagnation in front of the rotor.…”

Section: Introductionmentioning

confidence: 99%

How does turbulence change approaching a rotor?

et al. 2018

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Abstract. For load calculations on wind turbines it is usually assumed that the turbulence approaching the rotor does not change its statistics as it goes through the induction zone. We investigate this assumption using a nacelle-mounted forward-looking pulsed lidar that measures low-frequency wind fluctuations simultaneously at distances between 0.5 and 3 rotor diameters upstream. The measurements show that below rated wind speed the low-frequency wind variance is reduced by up to 10 % at 0.5 rotor diameters upstream and above rated enhanced by up to 20 %. A quasi-steady model that takes into account the change in thrust coefficient with wind speed explains these variations partly. Large eddy simulations of turbulence approaching an actuator disk model of a rotor support the finding that the slope of the thrust curve influences the low-frequency fluctuations.

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“…Branlard et al (2016) emphasize that further investigations are necessary to conclude whether the effects of the stagnation on the turbulence 20 are systematic or not (see also Branlard, 2017, which is an expanded version of Branlard's thesis). Simley et al (2016) measure the turbulent inflow towards a Vestas V27 wind turbine using three synchronized continuous wave, scanning Doppler lidars. They clearly see the stagnation in front of the rotor and also a slight rotation of the inflow.…”

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confidence: 99%

How does turbulence change approaching a rotor?

Mann¹,

Peña²,

Troldborg³

et al. 2017

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Abstract. For load calculations on wind turbines it is usually assumed that the turbulence approaching the rotor does not change its statistics as it goes through the induction zone. We investigate this assumption using a nacelle-mounted forwardlooking pulsed lidar that measures low frequency wind fluctuations simultaneous at distances between one half and three rotor diameters upstream. The measurements show that below rated wind speed the low-frequency wind variance is reduced by up to 10% at one half rotor diameter upstream and above rated enhanced by up to 20%. A quasi-steady model that takes into 5 account the change of thrust coefficient with wind speed explains these variations partly. Large-eddy simulations of turbulence approaching an actuator disk model of a rotor support the finding that the slope of the thrust curve influences the low-frequency fluctuations.

show abstract

Characterization of wind velocities in the upstream induction zone of a wind turbine using scanning continuous-wave lidars

Cited by 99 publications

References 14 publications

Evaluation of single and multiple Doppler lidar techniques to measure complex flow during the XPIA field campaign

Evaluation of single and multiple Doppler lidar techniques to measure complex flow during the XPIA field campaign

How does turbulence change approaching a rotor?

How does turbulence change approaching a rotor?

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