Stuttgart, Germany [RenewableEnergyWorld.com] Wind energy, currently regarded as an important source of renewable energy, is dependent upon the optimal operation of the newest generation of large wind turbines. This is possible through reliable measurement of the wind inflow characteristics. Experience has shown that the accurate power generation estimation based on wind speed is a challenging task and that for large new turbine models, conventional met mast wind speed measurements are not feasible due to cost and technical considerations.
But researchers at the Endowed Chair of Wind Energy (SWE) of the University of Stuttgart are working together with researchers from the University of Oldenburg and other project partners on an alternative remote sensing technique for wind energy applications. LIDAR technology (Light Detection and Ranging) is a laser-based measurement technique that performs wind field measurements in a more flexible and economical way. Currently, LIDAR is the best candidate to replace the met mast based wind measurements used in power curve calculations for offshore wind farms.
LIDAR systems detect wind speed and direction based on the time delay of the laser beam reflected by airborne aerosols. This technology has been used for decades, mainly for atmospheric research. In recent years the wind energy industry has seen the advantages of this technology for wind field measurements. This research project aims to further develop LIDAR technology for wind energy applications. The objective is to establish this measurement technique as a quality standard for wind field measurements with the spatial and temporal resolution needed by the wind energy industry.
The research concentrates on two main topics, namely, power curve assessment and wind field measurement from the nacelle. The first deals with ground-based approaches to replace conventional anemometers mounted on a met mast. The second aims at the development and verification of new nacelle-based approaches to measure inflow and wake wind fields. Control strategies and far wake models are also developed and tested with the measurements.
The SWE has assembled a group of partners to evaluate a commercial LIDAR system supplied by Leosphere. The research center, ForWind, at the University of Oldenburg will work on new methods for unsteady power curve estimation. The German Aerospace Center (DLR) will bring its experience using LIDARs for atmospheric research and airplane wakes. Power curve measurements will be performed on an onshore five megawatt (MW) prototype wind turbine belonging to Multibrid GmbH in Bremerhaven.
At this site, SWE will carry out measurements on a 102m met mast. The German Wind Energy Institute (DEWI) will supply its experience on standardized power curve measurements, with support from the offshore measurements conducted at the research platform FINO1 in the North Sea.
The results of this project supported by the German Federal Environment Ministry will be made available to the entire wind energy community. Moreover, the results will provide essential input for a scientific support program for the German offshore test site “Alpha Ventus.” This offshore wind farm, located 45 kilometers north of the island of Borkum, will begin operation in the fall of 2008.