Monday 20th of June, Rannveig Oftedal Eikill succesfully defended her master thesis with the title "An Investigation of Single Wind Turbine Wakes with Static LiDAR Wind Profilers". She is now holding a master degree in Energy with the specialization Renewable Energy - Wind Energy. She has been a student at the University of Bergen.
The work was performed as part of NORCOWE and supervised by Prof. Joachim Reuder (main supervisor) and PhD student Valerie Kumer and Prof. Finn Gunnar Nielsen (co-supervisors).
Rannveig's master project is mainly based on the data of three static LiDAR wind profilers that were deployed during the seven month field experiment WINTWEX-W at ECN's test site in Wieringermeer. The campaign was focused on capturing the structure and dynamics of the wake of a NORDEX N80 research wind turbine and has created a unique dataset for corresponding investigations. For this study also sonic anemometer and temperature difference measurement from a 108 m meteorological mast and SCADA data from the wind turbine have been used, in addition to the static LiDAR wind profiler datasets. The compilation of a reliable LiDAR dataset for the campaign has been accomplished through a thorough re-examination of the raw measurements, and the development and application of an advanced de-spiking routine. Combining atmospheric data with SCADA data from the turbine, measurements of horizontal wind speed deficits and turbulence intensities in the wake region were analysed with respect to both atmospheric boundary layer stability and blade pitch angles.
The results show an increased wake effect for stable stratifications in general, with wind speed deficits larger than 40%, and an increase in absolute TI of more than 10%. The main efect of the blade pitch happens in the angle interval between 0 and 3 degrees. For pitch angles exceeding 3 degrees, stability seemed no longer to have an significant effect on the wake strength, which additionally becomes substantially reduced.
Rannveig O. Eikill (right) and Valerie Kumer at NORCOWE day last year
Eikill's master thesis is available to NORCOWE members in ProjectPlace.