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U.S. finishes wind turbine radar interference trials

The FAA and other U.S. government agencies have completed the third and final operational field test in a two-year, $8 million program to study the physical and electromagnetic interference between radar systems and wind turbine farms, and to identify mitigation techniques to address this issue.

Data from the third Interagency Field Test and Evaluation of Wind Turbine-Radar (IFT&E), designed to assess near-term mitigation and to help develop long-term mitigation techniques, is being analyzed by Sandia National Laboratories and the Massachusetts Institute of Technology Lincoln Laboratory. The test took place in April.

Interference with radar has been a safety concern for both the FAA and the military, as well as a key roadblock to developers of new wind turbine farms, both in the U.S. and abroad.

Energy needs are accelerating plans for new wind farms, and elevating the priority for finding mitigation measures for radar interference. According to the U.S. Department of Energy (DOE), since 2000 wind power-generation capacity in the U.S. has increased from 5 gigawatts to 60, and could increase to as much as 305 gigawatts by 2030, supplying about 20% of U.S. electricity needs.

“To accommodate future wind energy growth in the United States, new technologies are needed to mitigate interference impacts from wind turbines on radar systems, which include decreased sensitivity, false targets, and corrupted track quality,” says the Energy Department.

U.K.-based startup Aveillant, which is developing 3-D holographic radar systems to counter the problem, says when wind farms are located within 20 nm of an airport, reflections from the rotor blades can mask the position and altitude of aircraft in a large area near the facility. The interference, known as “clutter,” appears as a large clump on air traffic control radar screens and can be confused with a weather cell, according to Aveillant. Primary returns from aircraft in the vicinity—including range and bearing—are generally lost near the wind farms, though secondary surveillance from aircraft with functioning transponders is typically not affected. The FAA, military and homeland security agencies are also concerned about the effects on long-range radar systems.

The IFT&E program analyzed wind turbine interference during three multi-day tests in which long-range, terminal and other radar systems were used to track a variety of test aircraft flying around and over wind farms in Minnesota and Texas.

The April test took place in King Mountain, Texas, home to a 280-megawatt wind farm with 214 turbines.

“The laboratories’ technical evaluation of the most promising technologies will be used by FAA to validate and accelerate the new mitigation technologies for temporary deployment into the national aviation system,” says the Energy Department. “In addition, the agencies are developing a longer-term plan involving more permanent solutions that can be applied to both land-based and offshore wind turbines.”