LiDAR wind measurement in complex terrain: GEO-NET is Trusted Service Provider for ZX LiDARs

Based on this vast experience, the LiDAR manufacturer ZX-LiDARs has now appointed GEO-NET as a "Trusted Service Provider" for ZX-LiDARs. With the 24th anniversary of GEO-NET these are more than enough reasons to celebrate: That is why the experts from Hanover today grant a 24 % discount on wind measurement services. Visit us on our homepage under www.geo-net.de for further information and secure your discount voucher!

Wind measurements in complex terrain are anything but trivial, but absolutely necessary - if no suitable reference data from neighbouring wind farms are available during the planning of a wind farm, the uncertainties of an energy yield calculation increase to such an extent that the calculation is no longer bankable.

Even with a simple wind measurement in flat terrain, many details have to be taken into account in order to comply with the relevant international standards such as TR6, MEASNET and IEC61400-12-1 and thus ensure the bankability of the measurement. In complex terrain, the terrain poses additional challenges: since the wind field changes significantly over short distances due to obstacles such as hills, slopes, valleys, cliffs, etc., the wind measurement can only be used for an energy yield assessment within a radius of about 2 km, so several measurements are necessary for a large wind farm. With classical wind measuring masts this quickly becomes very complicated, especially as a met mast and its foundations require sufficiently flat terrain - at some locations it is simply not possible to erect a mast because it is too steep. Modern LiDAR devices are much more flexible in this respect: the compact devices are much easier to set up, do not need a building permit and are easier to maintain. In complex terrain, however, they have a system-related disadvantage resulting from the measuring principle: the wind speed is measured with several laser beams that measure in different directions at a certain angle to each other and produce wind speed and wind direction by vector calculation. However, this only works as long as the wind field is homogeneous in all directions. In complex terrain, for example when the wind flows over a hill or crest, this homogeneity is no longer given, which leads to measurement errors.

An internationally accredited consultant like GEO-NET can estimate this error in advance, and thus identify the location for the LiDAR-devide that produces the smallest measurement error on the one hand, and correct the measurement error in the actual measurement results on the other. For this purpose, the experienced experts from Hanover use the three-dimensional flow model FITNAH-3D, which has proven itself especially in complex terrain and has been validated for this purpose at numerous locations. With this model GEO-NET generates a map showing the deviations of a LiDAR measurement from the actual wind speed. This map serves as a basis for the selection of the measuring site and for the later error correction. In this way, the uncertainties of a LiDAR measurement in complex terrain can be significantly reduced.