Windcube TM Pulsed lidar wind profiler Overview of more than 2 years of field experience J.P.Cariou, R. Parmentier, M. Boquet, L.Sauvage 15 th Coherent Laser Radar Conference Toulouse, France 25/06/2009
Presentation Outline 1. Wind Energy requirements for remote sensing 2. How can we meet these needs in flat terrain? 3. Example of some comparison campaigns vs. cup anemometry 4. Complex terrain: an exciting research field 5. Remaining challenges 6. Conclusion and questions 2
Wind Energy requirements for remote sensing Different needs: Initial site assessment: easy to deploy measurement device to measure at hub height (80m to 100m) Site calibration: wind shear and turbulence characterization for the site Micro-siting: fast and easy to move remote sensor in complement with few fixed small met masts Power Performance verification: accurate measurement over the whole rotor diameter (~40m to ~180m) But the same high accuracy requirement: Less than 0.1m/s uncertainty on horizontal wind speed (10min average) Accurate measurement of vertical wind, turbulence (standard deviation over 10min periods), and wind direction An industry that is used to measurement standards and traceable calibration process 3
WLS7 Windcube Doppler Lidar Specifications Specifications Ground layer WLS7 Minimum wind data height 40m Maximum wind data height Up to 200m* Averaging time 0.5s Vertical range resolution 20m Number of programmable heights 10 Wind speed accuracy < 0.2 m/s Wind direction accuracy < 2 Speed range 0 to 60 m/s *According to atmospheric conditions Parameters Output data Wind speed and direction Turbulence data 4
How can we meet these needs in flat terrain? With a strong knowledge of all sciences involved in the Lidar design: Optoelectronics: laser + high power amplifier + detection module Optics: optical system design + light propagation in the atmosphere Signal Processing: need for information theory limited Doppler shift detection processing (MLE e.g..) Electronics and computing: energy efficient electronics and optimized coding for the algorithm to perform fast and accurate calculations Mechanics: ensure the same level of accuracy over a broad range of operating conditions (temperature, humidity, With months (years?) of testing against reference cup anemometry across different sites and atmospheric conditions You accumulate a large knowledge base on the behavior, strenghs and weaknesses of your system You know its limits You can improve it and push it to its limits (as there is always a trade-off between your design, its cost and its performances) 5
Brief overview of several different measurement campaigns The Royal Netherlands Meteorological Institute (KNMI) Comparison up to 200m Measurement of very strong shear and direction change with height Beijing Institute of Atmospheric Physics (IAP) Measurement up to 200m inside Beijing City (urban conditions) Deutsche WindGuard GmbH Flat terrain in north Germany 135m met mast Class 1 reference cup anemometers, regularly calibrated Several Windcubes TM production units deployed 6
1 week of measurement at KNMI: the site Lidar KNMI 220m met tower (left) and Windcube TM seen from the tower s top (right picture) Cabauw, The Netherlands. 1 week 24 to 30 August 2007 all data included, no filtering Reference heights for comparison: 40m, 80m, 140m, 200m. WindcubeTM scanning cone angle: 30. 10 different heights in the range 40 220m. Lidar data output frequency: 0.5 Hz. 7
1 week of measurement at KNMI: the results 40m 200m Results summary: 8
KNMI measurement campaign: focus on bad weather conditions (1/2) Night Day strong wind shear and wind veer combined with low level clouds and rain 9
KNMI measurement campaign: focus on bad weather conditions (2/2) Night Day 10
1 week of measurement at IAP: the site Beijing City, Public Republic of China. 1 week December 2007 all data included, no filtering Reference heights for comparison: 40m, 80m, 140m, 200m. WindcubeTM scanning cone angle: 30. 10 different heights in the range 40 220m. Lidar data output frequency: 0.5 Hz. 11
1 week of measurement at IAP: the results 12
Deutsche WindGuard Lidar test station 135m mast equipped with cup anemometers and 3D sonic anemometers Refer to: A. Albers et al.: Comparison of Lidars, German test station for remote wind sensing devices, presentation at DEWEK 2008, Bremen, Germany, November 2008. 13
Deutsche WindGuard: comparison results Very good correlation with almost no offset Good correlation despite completely different measurement process see Ribstein et al. poster at EWEC2009 conference: Simulation of Heterodyne Pulsed Lidar: Effect of measurement process on average wind speed and turbulence measurement 14
Deutsche WindGuard: reproductibility test Same behavior: good manufacturing reproducibility Remaining signal processing issue corrected since the test was performed (see A.Albers paper for more details) 15
Research activities on complex terrain Refer to M.Boquet presentation, CLRC 2009 Refer to F.Bingöl presentation, EWEC 2009 16
Remaining challenges Technological challenges: Optoelectronics reliability in the field Fluid dynamics challenges: Better understand the effect of volume and time averaging on standard deviation measurement Understand, predict and correct differences with cup anemometry in complex terrain Shear and turbulences effects on wind turbines efficiency Operational challenges: Shocks and vibrations during transport All-weather operation (snow, rain, storms, scorching heat ) Remote power supply 17
Axane Windcube TM power pack H 2 fuel cell based solution Up to 3 months operation without refilling Silent and clean energy solution Can be complemented by solar panels and small wind turbine 18
50+ WINDCUBES DEPLOYED AROUND THE WORLD SINCE DEC 07 19
Thank you, Any questions? 20