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Figure 69: Comparison of Windcube 10-min averages with calibrated mast at Risø Høvsøre
5.4 Conclusions and perspectives
This chapter summarizes the principles of operation, the performances and critical parameters
of Doppler pulsed wind lidars, such as the WINDCUBE lidar from LEOSPHERE. It takes into
accountthe different steps ofthe velocitymeasurement process.Thisdetailedprocess analysis
provides the backbone for a pulsed lidar development, optimization and issues related to serial
production.
More generally, pulsed and CW lidars have shown great reliability and accuracy in the
measurement of wind characteristics such as horizontal and vertical wind speed and wind
direction at various heights on flat terrains and offshore (Courtney et al., 2009; Westerhellweg
et al., 2010).Thehigh datarecovery rate up toabove bladetop ensuresahighqualityanalysis
of the wind conditions available on the project site, leading to an optimized layout design and
the choice of the suitable turbines.
Regarding future improvements, the measurement of additional wind parameters like turbulence
intensities, kinetic fluxes or inflow-angles is under investigation at the present time
and should be available in the near future.
One of the remaining challenges is also reaching high accuracy in complex terrains where
flow distortion occurs and impairs the lidar wind components retrieval from measured radial
velocities. Since lidar radial velocities are still very accurate even on complex and rough
terrains, a methodology using CFD modeling has been recently developed to avoid taking
the flow homogeneity assumption (Boquet et al., 2009; Bingöl et al., 2009; Boquet et al.,
2010a).Eventhoughnew, thismethodologyhas alreadyshowngoodresultsonsitesofvarious
complexities. The measurement of additional wind parameters like turbulence intensities,
kineticfluxesorinflowanglesisunderinvestigationatthepresenttimeandshouldbe available
in the near future.
To sum up, lidar anemometry has already proven its great utility in the development of
wind farm projects, as an instrument allowing considerable financial gains through a better
understanding of the wind conditions at a site and therefore reducing the capital risk of
the investors (Boquet et al., 2010b), but also for operational power curves measurements
118 DTU Wind Energy-E-Report-0029(EN)