Homeowners living near wind farms in Germany have voiced concerns over the continual flashing of safety beacons atop wind turbines – meant to warn low-flying aircraft and prevent collisions. The residents say the lights are an annoyance, especially in larger wind farms.
A new radar detection system that switches beacons on only when necessary could promote better community relations and ensure wind energy development in the country stays on track.
Engineers from the Fraunhofer Institute for High Frequency Physics and Radar Techniques together with private firm Industrial Electronics and wind farm engineering company Dirkshof Wind GmbH have developed project Parasol, whereby anti-collision beacons only begin blinking when a radar device detects an aircraft is approaching a wind farm at a dangerous altitude.
This considerably shortens the time the warning lights are flashing, says Heiner Kuschel, department head at Fraunhofer in Wachtberg.
“The collision warning lights only switch on when an airplane is within a radius of four kilometers and flying below an altitude of about 2500 feet (700 meters). We use the passive radar sensors to essentially extend a protective umbrella over the wind farm like a parasol.”
Unlike active radar used in air traffic control that requires expensive licensing, the Parasol is called a passive radar system because it taps into local radio station frequencies to find local aircraft around wind farms. According the Institute, these digitised signals are particularly suited to vectoring in on moving objects.
The Parasol radar unit captures radio waves bouncing off air traffic and calculates distance, position, and velocity of the approaching aircraft. This data is fed to a computer that then decides whether to switch on the beacons.
A prototype has already been installed and successfully tested at a wind farm operated by Dirkshof in the town of Reußen-Köge near Husum, Germany.
“We are able to operate the system without a transmitter module of its own, and dependent on weather conditions. A transmitter license required for active radar systems it not required for this, so it can be operated cost-effectively,” Kuschel said.
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