06 LIDAR SUPPLEMENT


steerable scan heads, invented, designed and manufactured by Risø DTU in close collaboration with Natural Power and a Danish industrial design company IPU (DK).


Turbine integrated lidars for steering and control Wind turbines are often placed in areas where powerful winds are common and, if they are not


now possible to obtain pre-vision and forecasting of the incoming wind gusts and shear. Detailed monitoring of the upwind inflow


conditions, in combination with new (to be developed) active feed-forward control, opens up many new possibilities for minimising the loads and increasing the efficiency and hence the life-time of turbines and wind farms. Several time scales for the wind measure -


ments and the corresponding systems will be involved. The typical 10-minute sampling period of wind data for wind surveys may be adequate for controlling the turbines yaw. But this time scale is not short enough to characterise the impact of local turbulence on the turbine performance. Wind gusts detected 100-200 meters


Long-range wind scanners at work (concept) Test work is progressing, in our laboratory


and in the fields around Risø DTU, to calibrate and performance-test these new short range WindScanners. The first outdoor wind and turbulence studies have been performed in the spring of 2011 (“Six-beam” 3D turbulence profiling experiment, and “Small hut wind wake flow and turbulence visualisation”).


Long-range (0.1 – 6 Km) WindScanners In addition, in collaboration with the French lidar manufacturer Leosphere, IPU and Risø DTU have also engaged in the design and manu - facturing of three new two-axis mirror-based steerable scan heads, and integrated them with three WindCube200 lidars to power WindScanners for long-range applications. Testing of hardware and software for jointly steering and controlling these long-range wind scanners is in progress in collaboration with Leosphere. The long-range WindScanners have since


become available commercially from Leosphere as 2D beam-steerable wind profilers (Windcube200S), with a nominal measurement range during typical atmospheric conditions out to 6000m. The first field testing of the long-range


WindScanners took place at Nice airport and Marseilles airport in France during April-May this year.


International Sustainable Energy Review Volume 5, Issue 3, 2011


Engineers from Leosphere and IPU behind the scan head on a long-range WindScanner during a lab test at RISO DTU


» Wind gusts detected 100-200 meters upwind typically impact the turbine rotor on a 10 s scale, timely enough to feather or pitch the blades «


optimally trimmed and aligned into the gales, they can be exposed to excess loads or even be destroyed. By use of lidars mounted on the nacelle, or integrated into the spinner or the blades, it is


upwind typically impact the turbine rotor on a 10 s scale, timely enough to feather or pitch the blades. The turbine rpm is another variable that can be adjusted to prevent damage on that time scale. Blades provided with active trailing edge flaps require wind data acquired at even shorter (sub-second) time scales. A first turbine-mounted lidar capability was


achieved in a proof-of-principle experiment in 2003, in which a prototype ZephIR lidar was placed on the nacelle of a Nordex N90 turbine5


.


This experiment demonstrated the feasibility of wind speed measurements at ranges up to 200m in front of the turbine. In 2009, a continuous wave (CW) conically-


scanning wind lidar (ZephIR) was installed in the spinner of a large 80m diameter, 59m hub


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11