Measuring Wind Farm Effects over the North Sea with Two Aircraft Measurement data pool for realistic predictions of the energy yield of offshore wind farms

For the X-Wakes project, two aircraft are being used in a measurement campaign this summer to investigate the spatial distribution and recovery of the wind field in front of and behind offshore wind farms. An extensive data set is being collected for the project to analyse the wind conditions over the North Sea and the interaction of wind farms and the atmosphere. For the last measurement flights in the project, two research aircraft from Technische Universität Braunschweig are even being used simultaneously for the first time.

The Cessna F406 D-ILAB, the new research aircraft of TU Braunschweig, measures the inflow conditions in the measurement campaigns; the Dornier 128 D-IBUF measures the atmosphere behind the wind farms. Both aircraft are equipped with a nose mast to measure temperature, humidity and wind, and the Dornier 128 with cameras and a laser scanner to measure the swell. The simultaneous coordinated flights allow temporal and spatial differences to be determined separately.

The previous flight-based measurement data in front of and behind offshore wind farms with the Dornier 128 are also unique worldwide. After the end of the project, they will be publicly available in their entirety and will subsequently be available to research and industry for the validation of models.

In the X-Wakes project, further measurement data is also available in the area of the North Sea and from satellites. The data is used to further develop models of varying complexity. The aim is to obtain realistic predictions of the yield of offshore wind farms in order to optimise the further expansion of wind farms on the North Sea.

“We have a short time window for the measurements with two aircraft: since 2020, the new research aircraft D-ILAB has been in operation, replacing the D-IBUF after more than 35 years in the service of research at TU Braunschweig. In autumn, the D-IBUF will come to the Deutsches Museum in Oberschleissheim,” explains the scientific spokesperson of the project, Dr. Astrid Lampert from TU Braunschweig.

Project data:

The X-Wakes project is being carried out in a large consortium coordinated by the Fraunhofer Institute for Wind Energy Systems. Project partners are the Institute of Flight Guidance at TU Braunschweig, the Eberhard Karls University in Tübingen, the Helmholtz Centre Geesthacht, the Karlsruhe Institute of Technology, the University of Oldenburg, and UL International GmbH. Various wind farm operators and the Federal Maritime and Hydrological Agency are involved in the project as associated partners. The research project is funded by the Federal Ministry for Economic Affairs and Energy.

Background:

The area that can be used for wind energy in the German Bight is limited. Therefore, wind farms are usually built in groups, so-called wind farm clusters. Such clusters can consist of several hundred wind turbines. While wake currents are generated behind the turbines, upstream the wind is reduced by upstream effects. As a result, the turbines encountered by the wake convert less energy and are more heavily loaded. Under certain atmospheric conditions, wakes can extend over distances of more than 50 kilometres.