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Testing

Photo of a large wind turbine blade sticking out of the structural testing laboratory; it is perpendicular to a building at the National Wind Technology Center.

A multimegawatt wind turbine blade extends outside of the structural testing facility at the NWTC. PIX #19010

Testing capabilities at the National Wind Technology Center (NWTC) support the installation and testing of wind turbines that range in size from 400 watts to 5.0 megawatts. Engineers provide wind industry manufacturers, developers, and operators with turbine and component testing that ensures performance and reliability. Prototype testing is especially important to capture manufacturing flaws. The NWTC staff conducts tests on components in laboratory environments and on turbines in the field to produce data that can be used to certify and validate turbine designs. Evolving over more than thirty years, with the support of the U.S. Department of Energy, the NWTC has developed test equipment, methods, and data acquisition to foster wind technology testing.

We offer capabilities in structural testing, drivetrain testing, and field testing. The capabilities are supported by world-class testing facilities.

Structural Testing

Structural testing of wind turbine blades and system components reveals design and manufacturing problems at an early stage of development and leads to overall improvements in design, performance, and reliability while reducing the risks inherent when commercializing new designs. Blade testing is a requirement for type certification. As part of the blade certification process, blades are subjected to a test matrix including a series of static and fatigue load cases. A typical load matrix consists of:

  • Property testing, including mass and center of gravity tests and modal characterization.

  • Static load cases where a bending moment is applied to the blade to simulate extreme load events the blade is expected to survive during the blade lifetime.

  • Fatigue testing which applies highly accelerated dynamic loads in flapwise and lead-lag directions to simulate the equivalent loads the blade is expected to endure during its lifetime.

The NWTC is accredited by the American Association of Laboratory Accreditation (A2LA) to perform testing to the IEC 61400-23 blade test standard.  The NWTC has operated wind turbine blade structural testing facilities since 1990 and during this time has tested hundreds of blades. The NWTC has pioneered the development of innovative test systems which both improve test accuracy and decrease the time of a typical test program.  One fatigue test method developed at the NWTC is the Universal Resonant Excitation system which has been commercialized as a standard industrial product.  The centers' experienced staff is proficient in testing and provides engineering expertise on best design practices.

See our Blade Test Facility Specifications.

Drivetrain Testing

Dynamometers are an effective means by which new drivetrain designs can be validated. The NWTC has dynamometer testing facilities that can test turbine drivetrains from the smallest turbines under 10 kW to the largest at 5 MW. Read about our Dynomometer Test Facilities and see the Dynamometer Facility
Specifications
.

Field Testing

Full-scale turbine testing at the NWTC encompasses a wide range of activities that provide high-quality testing support for wind technology projects. Field tests include turbine structural dynamic characterization and full-scale modal testing. Our testing validates performance and reliability and is especially important in capturing manufacturing flaws and identifying damaging operating conditions such as resonance, both of which may cause fleet-wide retrofits after commercialization.

  • Power performance, noise, loads, and power quality testing: NREL is one of only two facilities in the United States with testing capabilities accredited by the A2LA.

  • Modal Testing: Full-scale turbine modal testing helps design engineers determine the system's natural frequencies, damping values, and mode shapes. Modal tests ensure that the operational conditions preclude resonant frequencies, thereby minimizing dynamic loads and lengthening the life of the turbine. In addition, full-scale modal survey results are used to validate structural and controls models that wind researchers develop to improve the performance of wind turbines. The NWTC also conducts component-level modal testing of wind turbine blades, drivetrains, and towers.

  • Aerodynamics Testing: NWTC has conducted many tests that support turbine R&D, most notably the NREL Unsteady Aerodynamics Experiment in the NASA-Ames Wind Tunnel. This research acquired data sets for more than 1,700 different turbine conditions that are a valuable resource for developing and validating wind turbine aerodynamic codes.

As a facility accredited by the American Association of Laboratory Accreditation (A2LA), the NWTC enables turbine manufacturers and wind plant developers to meet wind turbine certification, financial, and other oversight requirements throughout the world. NWTC field testing personnel are members of standards committees for the International Electrotechnical Commission and the International Measuring Network of Wind Energy Institutes (MEASNET). Efficient quality control processes performed by the NWTC produce reliable test results in accordance with international standards.

Read about our Field Test Sites.

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