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Fraunhofer IWES, Enertrag and GEO-Net Research Improved Wind Prognosis

Bremerhaven, Hannover, Dauerthal / Germay - With the increasing development of wind farm sites in complex terrain, the demands on the prognosis of wind conditions have also increased. Instead of linear models, 3D models are used. A current research project aims to further improve the quality of 3D models.

Under the management of the Fraunhofer Institute for Wind Energy Systems IWES, the project developer Enertrag, the wind experts from GEO-Net and other project partners are working together on a current research project to improve wind yield forecasts, especially at sites in complex terrain. With the scanning lidar a new technology is used, which enables area-based modelling of wind conditions.

Research project for the optimisation of wind field modelling

The new generations of wind turbines make it possible to use sites in uplands and forests, which would previously have been impossible to develop for economic wind farm operation. However, along with the ever-larger rotors, the growing hub heights, and the complex flow conditions over forests, mountains, and valleys, the forecasting of energy yields is also becoming increasingly challenging.

Simple linear models, such as those developed and used in the early days of wind energy, are therefore unsuitable for the complex wind conditions and the high demands on accuracy - sophisticated and computationally intensive 3D models have long been standard. In order to further improve the accuracy of these models, Fraunhofer IWES is carrying out the EWiNo project (development of a two-stage procedure for the assessment of wind sites with regard to their wind potential according to the EEG amendment 2017) in cooperation with the project developer Enertrag, the wind experts from GEO-Net and other well-known industrial partners from the wind industry. The project is supported by the Federal Ministry of Economics and Energy on the basis of a resolution of the German Bundestag (FKZ 0324225 A/B).

scanning Lidar measures wind conditions at any location in the wind farm area

For wind farm planning, wind conditions have so far been recorded with a lidar or measuring mast, by means of which the parameters wind speed and direction are measured at a location at the site of wind farms. The wind conditions are then transposed from this location using a model to the actual sites of the turbines in the farm.

In the EWiNo project a socalled scanning lidar is used as a new technology. With this version of the lidar device the wind conditions can be measured at virtually every point in a wind farm site. These measurements can subsequently be used to validate various 3D models such as FITNAH-3D and OpenFOAM, including under difficult conditions in forests and in complex terrain, so as to optimize the models.

The results will help to render yield forecasts more precise, including in forests and on complex terrain, and will thereby facilitate the planning of wind farms under such conditions in order, ultimately, to make their subsequent operation more efficient. Furthermore, methods were developed to al-low the measurements recorded with such scanning LiDAR devices to be employed in normal wind farm planning too.

For EWiNo, Enertrag as project developer, who also plans wind in the complex terrain of German up-lands, provides a site in Northern Hesse, where ideal research conditions for the use of the scanning lidar are available.



Source: IWR Online, 05 May 2020