With an increased focus on green energy production in recent years, more wind turbines or windmills are being installed to harness wind energy. Many modern wind turbines include blades having lengths in the range of about twenty-five (25) meters (m) to about ninety-nine (99) m. Furthermore, such blades are rotatably mounted on a mast whose height may range from about eighty (80) m to about one hundred and twenty (120) m. During conditions where sufficient wind is present to turn the blades, the blades rotate a turbine attached to an electric generator to create electrical power. This power may be used to supply additional electric power to the distribution grid, or may be used directly by the wind turbine owner. As the demand for renewable energy sources increases, the need for a greater number of wind turbines will increase. Multiple wind turbines are sometimes installed across expansive open areas grouped in wind farms to harness the power of the wind and convert it to electrical energy.
Ground based radars are a primary source of information regarding atmospheric conditions, location and quantity of water and/or ice, as well as other objects in the atmosphere. Existing ground based radar applications must meet certain criteria such as coverage, accuracy, latency, scan rate, reliability and resolution. Currently, ground based radars serve as a key component of national surveillance systems that detect and track objects operating in the nation’s airspace. In addition to applications in the defense industry, radar fulfills various civilian requirements. These civilian applications include but are not limited to air traffic control, weather surveillance and tracking, tracking airborne releases of toxic materials, calibration of satellite-based instruments, observing debris flow from disasters such as mudslides and floods, monitoring air quality, monitoring movement of volcanic ash, and detecting birds and other aviation hazards.
Wind turbines interfere with radar, particularly Doppler radar because of the time variable signatures generated by the rotating blades. The interference caused by wind turbines creates blind spots in the radar coverage when a wind turbine is installed in the line of sight of the radar installation. In the interest of national security, permission to install wind turbines in the line of sight of existing radar installations may be prohibited. Other remediation actions include additional processing intended to filter the wind turbine signature. However, such techniques risk corrupting the received data signal and may increase the likelihood that a threat will go undetected. Additionally, complex processing taxes the computer’s resources and timelines available in existing legacy radar systems. Additional air traffic rules may be implemented in areas near or above wind turbines. However, such measures do not address the situation where an airborne object does not comply with air traffic regulations.
The patented invention is a wind-turbine having radomes with radar sensors installed on the wing-tips thereof. A wind-turbine radar arrangement according to one embodiment is intended to solve various radar return problems caused by time-variable return signatures of large wind turbines. Further, the wind-turbine may provide the power required to operate the integrated radar system. Moreover, a radar system integrated onto the wing tips of a wind-turbine may include a complement of various operating frequencies adapted to maximize coverage with simultaneous imaging and surveillance. Such a radar-wind turbine system may also enable ISAR (Inverse Synthetic Aperture Radar)/SAR (Synthetic Aperture Radar) imaging radar capabilities. Thus, there is disclosed a radar system comprising an antenna configured to transmit and/or receive a radio frequency (RF) signal; and a processor in electrical communication with the antenna and configured to generate an RF signal for transmission and/or to process a received RF signal; wherein the antenna is mounted to a blade of a wind turbine such that relative motion is defined between the antenna and a target within a line of sight of the antenna.
Multi-use of wind turbines is gaining momentum as wind energy becomes popular around the world.
Patent Information
Patent Number: US 9,128,184
Patent Title: Radar wind turbine
Inventors: Bachmann; Svetlana M. (Liverpool, NY), Reitz; Elliott (Liverpool, NY)
Assignee: Lockheed Martin Corporation (Bethesda, MD)
Family ID: 1000000337564
Appl. No.: 13/803,264
Filed: March 14, 2013
Abstract: A blade mounted radar system comprises a wind turbine having a hub and blades extending therefrom; a radar antenna configured to transmit and/or receive a radio frequency (RF) signal; and a processor in electrical communication with the radar antenna and configured to generate the RF signal for transmission and/or to process the received RF signal. The radar antenna is affixed to one of the blades of the wind turbine such that relative motion is defined between the radar antenna and a target within a line of sight of the radar antenna. The problem of the ground based radar line of sight being obscured by the wind turbine is mitigated in this setup, as radar and turbine coexist in the same structure. Improved performance and additional capability are enabled by elevated installation and vertical SAR imaging capability. Doppler capabilities are extended using known motion of the antenna relative to stationary objects.