Wind Turbine impact to ATC radars - an assessment approach

The impact of Wind Turbine (WT) echo signals on diverse types of radars has been studied world-wide and with good success understanding the interference mechanisms in principal. However, there is a lack of practical approaches to calculate the acceptance for planned wind parks near radar stations. The officials commissioned with acceptability proving often refuse WT project request based on some simple rules dealing with “disturbance area assumptions”, mostly without real verification. One principal difficulty for elaboration of quantitative assessments is the need to know details about the radar internals, which may have a large impact to the radar sensitivity regarding WT interferences. So, without knowledge of the radar signal processing mechanisms, it is nearly impossible to predict the operational degradation caused by such disturbances. The calculation tool presented here deals with WT impact assessments on Air Traffic Control (ATC) radars under knowledge of certain radar key parameters related to antenna, waveforms, signal- and data-processing. Those key parameters may be delivered by the radar manufacturer to the officials to enable the quantitative calculations. For this purpose, a quantitative assessment tool predicting WT interferences was set up using the parameters of the German ASR-S radar. The interference results are expressed as detection probability per influenced area quantile along any aircraft path over or nearby wind farms, considering WT-type specific reflectivity characteristics and the WT emplacements in the landscape. The tool has been validated with real radar measurements.