Posters

Abstract

The project Windcal2.0 which finished in June, 2024 demonstrated that nacelle lidar calibrations could be faster and more accurate. The reduction in calibration time was achieved with a motion device (or a pan-and-tilt unit, PTU) that could switch automatically between lidar beams. The accuracy of the calibration was improved by developing a new reference sensor – a 2-D lidic system consisting of two short-range continuous wave lidars. Following on the good results and the recommendations made at the end of the project, another project was initiated to further improve the concept by switching from a 2-D to a 1-D lidic system. The main goal was to further reduce calibration uncertainty and simplify the measurement setup. To show this can be achieved a calibration of a 4-beam nacelle lidar with one lidic only as a reference was carried out in the period Apr-Aug 2025.  Ensuring good alignment between the nacelle lidar and the lidic was crucial. We verified that the nacelle lidar beams and the lidic beam were within 10cm of each other by detecting them on a wooden board with the help of an IR camera. The motion device on which the nacelle lidar was mounted would switch between lidar beams every two minutes.  Making sure that the setup was stable throughout the calibration was achieved by recording and monitoring the pan and tilt angles of the PTU and the lidar’s tilt and roll measurements.   The calibration results from the four beams of the nacelle lidar were very consistent with each other – both in terms of calibration constants and total uncertainty.   The method is currently appliable to 4-beam nacelle lidars but could be adapted to other types of lidars in the future.