Short-Range Doppler-Radar Signatures from Industrial Wind Turbines: Theory, Simulations, and Measurements

Industrial wind turbines are large constructions that require in-field monitoring. In this paper, short-range Doppler radar signatures of wind turbines are both mathematically analyzed and practically verified through simulations and experiments. Two custom-designed radar prototypes that operate at the C and K bands, respectively, are employed in the acquisition campaign. The unique features of the radar signal-in particular, some observed energetic flashes in the time-Doppler map-appear as curved lines for specific acquisition scenarios and/ or for nonstraight blades. Furthermore, it is demonstrated that the use of high-frequency radar systems is beneficial in terms of improved spectrogram resolution. Experimental results coming from a 50-m-height wind turbine and a curved-blade 12-m-height turbine are also discussed, in this paper, in the context of the provided theoretical and simulation frameworks. This paper paves the way for noncontact structural health monitoring of industrial-type wind turbines through portable low-cost Doppler radar sensors.