New Test Facility to Improve Wind Turbines

Premature failures of mechanical systems have a significant impact on the cost of wind turbine operations and thus the total cost of wind energy. Recently, the Energy Department's National Renewable Energy Laboratory (NREL) took a giant step forward in the quest for more reliable, lower-cost wind power with the addition of the new 5-megawatt (MW) Dynamometer Test Facility at its National Wind Technology Center (NWTC). The new facility dramatically expands the capability of NWTC engineers and their industry partners to verify the performance and reliability of wind turbine drivetrain prototypes and commercial machines.

NREL engineer Scott Lambert (left) and Project Manager Mark McDade discuss calibrations being done on the new dynamometer at the 5-MW Dynamometer Test Facility at NREL's National Wind Technology Center (NWTC). Credit: Dennis Schroeder.

The facility is capable of testing drivetrains up to 5 MW — large enough to test virtually any land-based turbine — and employs dynamically variable loading capabilities that will allow researchers to better simulate conditions a turbine might experience in the field.

"These new capabilities make this a very special facility, one of the largest and finest of its kind in the world," NWTC Director Fort Felker said. "It gives NREL an enhanced ability to do comprehensive testing of modern multi-megawatt wind turbine systems in a laboratory environment to verify their performance and reliability before they are widely deployed."

NWTC Director Fort Felker speaks at the November dedication ceremony for the new 5-MW Dynamometer Test Facility. Credit: Dennis Schroeder

A dynamometer system replaces the rotor and blades of a wind turbine and allows researchers to control the turbine drivetrain's mechanical and electrical systems while simulating normal and extreme operating conditions. Historically, this testing has been done under torque (rotating) loads only. The new state-of-the-art facility at the NWTC, funded with the support of the Energy Department and the American Recovery and Reinvestment Act (ARRA), incorporates a non-torque loading system into the testing regimen, a hydraulic device that allows for simulation of both the rotational and bending loads that a wind turbine rotor places on a drivetrain.

"The non-torque loading system is what really sets this facility apart from other comparable test sites," NWTC Dynamometer Project Manager Mark McDade said. "This allows us to test the drivetrain system with the types of loads that it will see in a real-world application. It's a very important feature for a test apparatus because the adverse impacts these types of loads can have on a system are significant."

The system features a 6-MW motor, which provides the power to a turbine during testing. The motor turns at very high speed and low torque. The motor drives a gearbox, which transforms the output to the high torque and low speed that is appropriate for a wind turbine drivetrain. This provides the rotating loads on the test article.

Add to this motorized torque testing the non-torque loading capability unique to the NWTC, and NREL is able to put a wind turbine drivetrain through the most realistic loading tests possible in a laboratory.

By David Glickson, NREL