Within the NORCOWE research center, the Geophysical Institute of the University of Bergen (GFI/UiB) and Christian Michelsen Research (CMR) has conducted a series of 3 field experiments, mainly dedicated to the characterization of inflow conditions and wind turbine wakes under various atmospheric conditions and for different locations.
The first campaign (LIMECS; LIdar Measurement Campaign Sola; Kumer et al., 2014) was performed from March to August 2013 at and around the Sola airport Stavanger in collaboration with the Norwegian Meteorological Office (MET) and the airport operator Avinor. We deployed two Windcubes v1 and a scanning Windcube 100S at two different sites in Sola, one next to the runway and the other one near to the autosonde from MET, in a distance of about 2.5 km. In combination with wind profiles up to 200 m (Windcubes v1) and 3 km (Windcube 100S) and temporally more frequent radiosonde ascents, we collect a variety of wind information in the coastal atmospheric boundary layer. Main research focus of the experiment was the validation of wind profiles measured by the scanning wind lidar system Leosphere WindCube 100S against radiosoundings for altitudes up to 3 km above the surface and the characterization of the system with respect of its capability to resolve relevant boundary layer phenomena in the coastal region, as land-sea breeze circulation and katabatic drainage flows. The results of the comparison with the radiosoundings show an increasing correlation of 0.95 to 0.99 for increasing measurement heights (125 to 1325 m) between the scanning LiDAR wind profiles and the radiosonde horizontal wind speeds. Though the number of LiDAR measurements decreases with increasing height, the measurements seem to correlate better with the radiosonde data in high altitudes. The scanning LiDAR data show also a high potential for boundary layer studies, such as the estimation of boundary layer height. A combination of RHI and PPI scans also allowed to capture even rather shallow land-sea breeze circulations and drainage flows.
The second campaign (WINTWEX-W, WINd Turbine Wake Experiment-Wieringermeer; Kumer et al., 2015; Kumer et al., 2016) was performed in collaboration with the Energy Centre of the Netherlands (ECN) from November 2013 to May 2014 at the ECN test site Wieringermeer. The test facility consists of a row of five Nordex 2.5 MW research wind turbines with a hub height and rotor diameter of 80 m. Around 3 rotor diameter upstream of the research turbine number 6 a met mast of 108 m measures upstream wind and temperature conditions at three and two different altitudes respectively. Additional to the standard met-mast instrumentation, we deployed one WindCube V1 upstream of the research turbine number 6 and two WindCube V1 and a WindCube 100s downstream, relative to the main wind direction. The downstream devices were located at 2, 5 and 12 rotor diameter distance aligned for winds coming from 210◦ south-west. After relocation on November 29th 2013, the locations changed to 1.75, 3 and 12 rotor diameter downstream along the wake line aligned for winds coming from 218◦ south-west. The Windcube V1s measured standard profiles at 40, 52, 60, 100, 108, 120, 140, 160, 200 m above ground level with a sampling frequency of 1 Hz. The scanning configuration of the Windcube 100s consisted of three Plan Position Indicator (PPI) and three Range Height Indicator (RHI) scans repeating every minute.
During parts of the campaign, the nacelle of the research turbine number 6 has been also equipped with an upstream looking Wind Iris and a horizontally oriented, downstream looking Zephir (ZPH328) nacelle LiDAR for the characterization of both inflow and wake.
The main results gained from the campaign so far include the investigation of the effect of atmospheric stability on averaged and normalized wind and turbulence intensity profiles (Kumer et al., 2015; Kumer et al., submitted to Remote Sensing) and on the spectral energy density (Kumer et al. 2016; Kumer et al., submitted to Remote Sensing).
The third and so far last campaign transferred the expertise and experience gained during the before described onshore campaigns to real offshore conditions. The OBLEX-F1 campaign, conducted between May 2015 and October 2016 at and around the FINO1 platform in the German Bight as international field experiment in collaboration with the Federal Maritime and Hydrographic Agency of Germany (BSH), the German Wind Energy Institute (DEWI), the Forschungs- und Entwicklungszentrum Fach¬hochschule Kiel GmbH (FuE Kiel GmbH) and AXYS Technologies. In addition to the heavily instrumented FINO1 tower, one static lidar wind profiler (operated by DEWI) and two scanning WindCube 100S were deployed on the FINO1 platform. Those instruments provided wind profiles up to 3 km above the ground as well as RHI and PPI scans for the investigation of the structure and dynamics of single turbine wakes of the adjacent Alpha Ventus wind farm. During specific meteorological conditions the scanning patterns were adapted to allow for the investigation of coherence in turbulence (Cheynet et al. 2016). One of the ground-breaking achievements of the OBLEX-F1 campaign was the first offshore deployment of a passive microwave temperature and humidity profiler (Radiometer Physics, HATPRO RG4) that allows for a detailed characterization of atmospheric stability over the whole atmospheric boundary layer up to at least 3 km above ground. The campaign was terminated in the beginning of October 2016 and the data are now in the basic quality control phase, which is, however, indicating a good data availability and data quality to be used in future studies.
Bogunović Jakobsen, J., E. Cheynet, J. Snæbjörnsson, T. Mikkelsen, M. Sjöholm, N. Angelou, P. Hansen, B. Svardal, V. Kumer, and J. Reuder, Assessment of wind conditions at a fjord inlet by complementary use of sonic anemometers and LiDARs, Energy Procedia, 80, 411-421, DOI: 10.1016/j.egypro.2015.11.445, 2015
Cheynet, E., J. Bogunović Jakobsen, J. Snæbjörnsson, J. Reuder, V. Kumer, and B. Svardal,
Assessing the potential of a commercial pulsed lidar for wind characterization at a bridge site, accepted for publication in Journal of Wind Engineering & Industrial Aerodynamics
Cheynet, E., J. Bogunovic Jakobsen, B. Svardal, J. Reuder, and V. Kumer, Wind coherence measurement by a single pulsed Doppler wind lidar, Energy Procedia, 94, 462-477, doi:10.1016/j.egypro.2016.09.217, 2016
Kumer, V., J. Reuder, M. Dorninger, R. Zauner, and V. Grubišić, Turbulent kinetic energy estimates from profiling wind LiDAR measurements and their potential for wind energy applications, Renewable Energy, 99, 12, 898-910, doi:10.1016/j.renene.2016.07.014, 2016
Kumer, V., J. Reuder, and R. Eikill, Characterization of turbulence in wind turbine wakes under different stability conditions from static Doppler LiDAR measurements, submitted to Remote Sensing
Kumer, V.-M., J. Reuder, and B. R. Furevik, A comparison on LiDAR and radiosonde wind measurements, Energy Procedia, 53, 214-220, DOI: 10.1016/j.egypro.2014.07.230, 2014
Kumer, V., J. Reuder, B. Svardal, C. Sætre, and P. Eecen, Characterisation of single wind turbine wakes with static and scanning WINTWEX-W LiDAR data, Energy Procedia, 80, 245-254, DOI: 10.1016/j.egypro.2015.11.428, 2015
Measurement campaigns carried out by NORCOWE: