Posters
Come meet the poster presenters to ask them questions and discuss their work
We would like to invite you to come and see the posters at our upcoming conference. The posters will showcase a diverse range of research topics, and will give delegates an opportunity to engage with the authors and learn more about their work. Whether you are a seasoned researcher or simply curious about the latest developments in your field, we believe that the posters will offer something of interest to everyone. So please join us at the conference and take advantage of this opportunity to learn and engage with your peers in industry and the academic community.
On 9 April at 17:15, we’ll also hold the main poster session and distinguish the 7 best posters of this year’s edition with our traditional Poster Awards Ceremony. Join us at the poster area to cheer and meet the laureates, and enjoy some drinks with all poster presenters!
We look forward to seeing you there!
PO148: Laser beam alignment of a scanning lidar in an offshore measurement campaign - an extension of the Sea Surface Levelling Method
Kira Gramitzky, Research assisstant, Fraunhofer Institute for Wind Energy Systems (IWES)
Abstract
Scanning lidars offer advantages such as a long range and the ability to cover large areas and multiple points, making them ideal for offshore applications and large wind farms. However, at these distances, precise alignment of the laser beam is crucial, as small deviations of 0.1° in distances of 5 km can shift the measurement point by around 8.7 m. On land, systematically placed hard targets are often used for levelling, but this is difficult and often impossible offshore. Sea Surface Levelling (SSL) provides an efficient alternative by using the sea surface as a reference. The water surface is scanned in as large a part of the 360°-sector as possible at a constant negative elevation angle, and the distance to the sea surface is estimated by analysing the CNR (carrier to noise ratio) signal that drops when the laser beam hits the water surface. If the device is perfectly aligned, the distance to the sea surface is constant in all directions for a fixed elevation angle. If not the deviations of the distances in different directions can be used to determine the tilt. This study extends the SSL method by scanning the sea surface at multiple ranges (different elevation angles). This allows not only pitch and roll to be determined, but also the elevation offset of the scanning lidar. Scans for the new SSL method were conducted by a scanning lidar deployed on a transition piece of a wind turbine. The results are compared to an external high-resolution inclinometer and CNR mappings of hard targets. The results show good robustness and reproducibility. The method provides reliable calibration without additional equipment in the field. After the SSL, only one hard target is required to estimate the north offset of the device, strongly relaxing practical limitations often faced in the field.
No recording available for this poster.
