As any remote sensor, standard WindCube wind reconstruction assumes flow homogeneity across the volume of measurement. In complex terrain, this assumption is no longer valid and measurements are inaccurate. To tackle this problem, Vaisala has developed a method allowing capturing flow inhomogeneity and obtaining accurate measurements in complex flow conditions.
Integrated within the WindCube, the FCR is an algorithm which associates the 10 minute average measurement of the WindCube with fluid mechanics equations in order to determine the wind velocity (ie wind speed and wind direction) for a given terrain topography. It embeds a 3D wind field model for complex terrain which has been configured to produce a mass consistent wind field using data from the WindCube.
It requires two types of data to be retrieved automatically:
- Site topography: the FCR uses corresponding topographic tiles from the embedded Shuttle Radar Topography Mission (SRTM) or Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) public database based on the configured GPS input. The database contains the terrain elevation at a 100 meter resolution for a 1 km*1 km square, downscaled at a 10 meter resolution.
- Wind measurements: wind speed and wind direction at several heights at a single location as measured by the WindCube standard wind reconstruction.
The FCR approach has achieved broad acceptance. Its performances have been proven on moderately complex terrain and forested terrain. The solution has been tested and validated by independent industry experts around the globe. FCR acceptance is effective: the German TR6 guideline accept its use without mast for moderately complex terrain.
The FCR algorithm relies on a patented technology.
Among others:
- CRES validation campaign, moderately complex site, Greece, 2010 (full report available)
- GL-Garrad Hassan validation campaign, moderately complex site, Canada, 2011
- JUWI validation campaign, moderately complex site, Germany, 2012
- Cowi / DTU validation campaign, moderately complex site, Bosnia, 2013-2014
- Acciona Energia / Barlovento validation campaign, moderately complex site, Spain, 2011
- Evaluation of wind measurement uncertainty of WindCube in complex terrain, Leopshere 2019
In addition, WindCube output data are also compatible with most CFD tools such as Meteodyn, WindSim, ZephyScience or some in-house models from consultants and can be used for post-correction purposes.