Posters

Abstract

So far it was only possible to estimate the probability of icing at one or several heights at a met mast before a wind turbine was built. Cameras, heated and unheated anemometers as well as temperature measurements have been used for this purpose. One of the objectives of IEA Task 52: Large-Scale Deployment of Wind LiDAR is the attempt to replace met masts with LiDARs in wind energy applications. Many studies and efforts are being made to solve the problems encountered in LiDAR practice, for example in complex terrain and cold climate. As production losses, increased load, risk of failure and noise emissions, as well as safety issues due to ice throw and fall are challenges for the operation of wind farms in cold climate, ice detection with LiDAR becomes an inevitable task. However, a satisfactory solution for ice detection with LiDAR that works in all different types of cold climate does not yet exist. First results of a method for detecting icing with LiDAR were not entirely satisfactory. Although all icing periods were detected, they were drastically overestimated. The criteria of temperatures below 0°C and cloud cover, which are measured by the meteorological station and the LiDAR, are not sufficient to reliably identify icing, as the information on the liquid water content of the cloud is missing. In the meantime, a concept for calibrating Wind LiDAR with ceilometer is developed. The ceilometer CL61 by Vaisala is not only capable of profiling the cloud, boundary and aerosol layer but also allows a straightforward identification of liquid and ice clouds, precipitation type and melting layer, and has an improved potential for monitoring aerosols, smoke, dust, and volcanic ash thanks to depolarization ratio profiling. Meteotest has started a collaboration with Vaisala to combine knowledge of icing with laser expertise. The aim is to provide a tool to determine the liquid water content of clouds and thus to detect icing not only at one height, but at the entire rotor plane of a wind turbine. From December 2023 to the end of March 2024 the ceilometer will be installed at two sites in cold climate in Switzerland. Both sites dispose of a 100m meteorological mast equipped with heated and unheated anemometers, temperature sensors at different heights, a camera filming an unheated anemometer and a Wind LiDAR. A Windcube V2.1 from Vaisala is installed at the first site and a ZX300 from ZX Lidars at the second site. In collaboration with Vaisala and the two LiDAR manufacturers we will analyse the icing events and try to find a way to calibrate the Wind LiDAR. The measurement setup and the first results of the icing detection will be presented at Windeurope Technology in Dublin.