Identification of Tower-Wake Distortion Using LIDAR Measurement

Abstract

In this present work, 10 minutes averaged concurrently measured wind data using collocated anemometers at 16.88 m height and Light Detecting and Ranging (LIDAR) at 16 m height, collected over a period of one month (June 1-June 30, 2014), have been analyzed to identify the tower wake distortion. lattice equilateral triangular communication towers with boom-mounted anemometers attached to it, not built but instrumented according to IEC61400-12-1:2005(E) standard is used for data collection. The Lidar and the collocated anemometers accurately identified the sectors affected by tower wake. In WS1 and WS2, the affected direction sectors are between 90-130° and 220-260°, respectively. The wind speed deficit using the collocated anemometers is up to 49% of the free stream velocity whereas that of the Lidar is up 58%. This is expected because the lidar measures consistently higher wind speed at the site than the anemometers. The secondary support structures such as cross and horizontal bracings, cable ladders, cable bundles and attachment brackets significantly influenced the wind speed and wind directions observed by the anemometers; requiring further investigation. A strong correlation between the data observed by two techniques demonstrated strong correlation after data treatment. The result shows that numerous communication towers scattered all over Africa can be used for resources assessment if proper investigated.