Mitigation of rotor blade-flash masking in passive radar collision warning system PARASOL

The passive radar based collision warning system for wind power plants PARASOL controls the switching of the warning lights on demand in order to increase acceptance of renewable energies in the population and avoid the attraction of birds by light emissions. The system design is composed of three passive radar sensors providing the location of potential targets by the measurement of time-difference-of-arrival (TDOA) of direct and reflected echo signals and calculation of the TDOA ellipsoid intersections. This paper primarily investigates a method of suppressing unwanted signal returns from wind turbines blades in passive radar systems. A signal processing procedure is proposed, which suppresses the returns of rotor echoes, while allowing the detection of target returns. The validity of this approach is demonstrated with data obtained from a PARASOL passive radar system.