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Ledbury, United Kingdom

Pedersen A.T.,Technical University of Denmark | Montes B.F.,LM Wind Power | Pedersen J.E.,NKT Photonics A S | Harris M.,ZephIR Ltd. | Mikkelsen T.,Technical University of Denmark
European Wind Energy Conference and Exhibition 2012, EWEC 2012 | Year: 2012

A short-range continuous-wave coherent laser radar (lidar) has been tested in a highperformance wind tunnel for possible use as a standard component in wind tunnels. The lidar was tested in a low as well as a high speed regime ranging from 5-35 m/s and 40-75 m/s, respectively. In both low and high-speed regimes very good correlation with reference measurements was found. Furthermore different staring directions were tested and taking a simple geometrical correction into account very good correlation was again found. These measurements all demonstrate the high accuracy of the lidar and indicate a possible future for short range lidars as a complement to LDA and other standard equipment in wind tunnels. Source


Trademark
Zephir Ltd | Date: 2016-03-30

Anemometers; Laser anemometers; Laser doppler anemometers; Ground based laser anemometers; Vehicle mountable laser anemometers; Buoy mountable laser anemometers; Ship mountable laser anemometers; Aircraft mountable laser anemometers; Airborne laser anemometers; Laser anemometers for true air-speed measurements; Laser anemometers for air turbulence measurements; Laser anemometers for measuring wind speed in a wind tunnel; Wind turbine mountable laser anemometers; Optical fibre based laser anemometers; Laser doppler velocimeters; Laser radars; Laser based wind speed measurement apparatus; Apparatus for measuring wind speed using infra-red radiation; Parts and fittings for all of the aforesaid goods. Maintaining and servicing anemometers, radars, velocimeters, laser based wind speed measurement apparatus, apparatus for measuring wind speed using infra-red radiation. Wind speed measurement services; Wind speed measurement services using laser anemometers; Wind speed measurement services using optical fibre based laser anemometers; Laser anemometry services; Laser doppler anemometry services; Ground based laser anemometers services; Vehicle mounted laser anemometers services; Buoy mounted laser anemometers services; Ship mounted laser anemometers services; Wind turbine mounted laser anemometers services; Aircraft mounted laser anemometers services; Laser anemometers services for measuring wind speed in a wind tunnel; Measuring of air turbulence using laser anemometers; Measuring true airspeed using laser anemometers; Laser doppler velocimetry services; Lidar services for acquiring wind speed measurements; Wind speed measurement services using lasers; Wind speed measurement services using apparatus incorporating a source of infra-red radiation.


Branlard E.,Technical University of Denmark | Pedersen A.T.,Technical University of Denmark | Mann J.,Technical University of Denmark | Angelou N.,Technical University of Denmark | And 5 more authors.
Atmospheric Measurement Techniques | Year: 2013

The aim of this study is to experimentally demonstrate that the time-average Doppler spectrum of a continuous-wave (cw) lidar is proportional to the probability density function of the line-of-sight velocities. This would open the possibility of using cw lidars for the determination of the second-order atmospheric turbulence statistics. An atmospheric field campaign and a wind tunnel experiment are carried out to show that the use of an average Doppler spectrum instead of a time series of velocities determined from individual Doppler spectra significantly reduces the differences with the standard deviation measured using ordinary anemometers, such as ultra-sonic anemometers or hotwires. The proposed method essentially removes the spatial averaging effect intrinsic to the cw lidar systems. © 2012 Author(s). Source


Barker W.,Natural Power Consultants Ltd. | Pitter M.,ZephIR Ltd. | Burin Des Roziers E.,ZephIR Ltd. | Harris M.,ZephIR Ltd. | Scullion R.,ZephIR Ltd.
European Wind Energy Conference and Exhibition 2012, EWEC 2012 | Year: 2012

A significant body of work has been amassed in support of the ability of lidar systems to accurately measure wind speed for wind resource assessment. Lidar measurements at heights significantly greater than those achievable with industry-standard mast anemometry enable reduction of project uncertainties through direct measurement of resource at hub height and reduction of uncertainty in measured shear profiles. Measurement of turbulence intensity (TI) at hub height also plays a role in wind resource assessment methodologies, site classification and turbine selection studies. Presented are the results of a comparison of TI measurements from ZephIR 300 and an IEC compliant 91.5m anemometer mast. The data was collected over more than 5000 hours of operation at the U.K.'s only dedicated lidar and sodar test site, operated by Natural Power in Worcestershire. Turbulence intensity measured by ZephIR 300 at typical turbine hub height is shown to be in good agreement with that measured by industry-standard anemometry. This is maintained across the wind speed and turbulence intensity ranges encountered during the test period over a full calendar year. Maximum variation between ZephIR and mast mean TI values of less than 15% is observed with variation in atmospheric stability conditions and measurement height for a typical one month deployment across the year. This is of the order of reported accuracy for industry-standard cup anemometry in the measurement of wind speed variance and demonstrates the ability of ZephIR 300 to measure TI values in flat terrain to an accuracy suitable for use in wind energy applications. Source


Barker W.,Natural Power Consultants Ltd. | Slinger C.,ZephIR Ltd. | Pitter M.,ZephIR Ltd. | Burin Des Roziers E.,ZephIR Ltd. | And 2 more authors.
European Wind Energy Conference and Exhibition, EWEC 2013 | Year: 2013

A significant body of work has been produced in support of the ability of lidar systems to accurately measure wind speed for wind resource assessment. Lidar measurements at heights significantly greater than those achievable with industry-standard mast anemometry enable reduction of project uncertainties through direct measurement of resource at hub height and reduction of uncertainty in measured shear profiles. Measurement of turbulence intensity (TI) at hub height plays a role in wind resource assessment through the estimation of energy losses due to turbine wakes and is also a key component of site classification and turbine selection studies. In the work presented here deviation in TI measurements observed at the ZephIR Ltd. IEC compliant tall mast test facility are considered in the context of a typical wind farm Energy Yield Analysis (EYA) methodology to determine the associated deviation in net Annual Energy Production (AEP) for calculations based on data from ZephIR 300 and the mast. For a typical turbine separation, wind speed distribution and direction distribution the deviation in net AEP with observed deviation in measured TI is small compared to that associated with the uncertainty attributed to other inputs to the EYA methodology. Analysis of the wake model implemented suggests that the results obtained should hold for general turbine layouts within the scope of the model. This result is considered as evidence of the ability of ZephIR 300 to measure TI values in non-complex terrain to an accuracy suitable for use in a typical wind farm energy yield analysis. Source

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