Polarimetric Time/Frequency characteristics of wind turbines as radar target (WM-PARSAX)

The global needs in development of ecologically friendly renewable sources of energy results nowadays in increasing number of wind turbines, which convert the wind energy into electricity. Efficient conversion requires that the scale of turbine's construction has to be in order of hundred meters, resulting in big linear velocities of rotated blades. For efficient solution of energy distribution and maintenance problems such turbines are constructed in groups forming so called wind-farms. Besides advantages of ecologically friendly energy source, the existence of such wind-farms in populated areas has some drawbacks, like disturbing wireless communications and disrupting operation of existing and future radars, which provide crucial information for air-traffic control, aerospace surveillance, weather nowcast and forecast. Rotating parts of turbines scatter incident electromagnetic signals with very wide continuous Doppler spectra. Such signals can be considered as moving clutter that hides reflections of targets like aircraft for ATC radars and rain for weather radars, and could not be suppressed using traditional/standard algorithms for radar signal processing.

Currently available techniques for mitigation of these negative impact and interferences mostly detect them and exclude �infected� spatial elements of radar coverage area from further processing and consideration. It results in degradation of radars performance and ability to provide necessary Quality of Service to sensing information users. The development of more advanced and efficient algorithms is currently limited by the limited depth of understanding of complex dynamic character of physical phenomena that are involved in such interferences formation.

The main goal of the project is to develop better understanding of electromagnetic waves scattering phenomena due to interactions between radar signals and wind turbine construction elements. Such understanding will result in development of appropriate models for radar �clutter� created by wind turbines and improved interpretation of the radar observations, and in finding radar observables and/or their derivations with most optimal features for efficient mitigation of wind turbines dynamic clutter in modern and future radars.

The project uses the combined research approach, which includes the theoretical development of simplified electromagnetic model of radar signals scattered by wind turbines, in different domains (range-slow time, range-Doppler, time-Doppler, for different polarizations and polarimetric parameters, etc.) in combination with application of this model as a tool for interpretation and understanding of experimentally measured radar data and their derivatives. The controllable simplification of the model, which considers only analyses of the most important radar observable electromagnetic and scattering effects, is expected to result in the development of computationally not complex, tractable tool for simulation, interpretation and understanding of radar observations. One of possible outcome from this study can be development of inverse technique, which will use measured radar micro-Doppler pattern to restore kinematic structure of the complex rotating construction and characterize its elements.