Wind Power Reliability Research
The U.S. wind power industry is well established, with nearly 75 gigawatts of installed capacity across the United States. Given this large base of installed wind turbines, NREL is increasingly researching ways to increase wind turbine reliability, with the goal of minimizing maintenance costs, improving capacity factors, and ultimately driving down the levelized cost of wind energy.
NREL's wind power reliability research for land-based turbines is focused primarily on gearboxes, blades, and how turbines interact with the electric grid. Offshore reliability capabilities include drivetrain analysis, data collection and analysis, and validating a variety of technologies and systems.
Wind Turbine Gearbox Reliability
Premature gearbox failures have a significant impact on the cost of wind power plant operations. In 2007, NREL initiated the Gearbox Reliability Collaborative, which includes wind turbine manufacturers, owners, researchers, and consultants. The project combines analysis, field research, dynamometer characterization, condition monitoring, and the development and population of a gearbox failure database in a multipronged approach to determine why many wind turbine gearboxes do not achieve their expected design life. NREL's dynamometer research facilities play a key role in the Gearbox Reliability Collaborative by validating new designs.
Wind Turbine Blade Reliability
Wind turbine blade failures are an extremely rare occurrence, but when they do happen, the results can be catastrophic. For this reason, blade manufacturers require tests of blade properties, static mechanical tests, and fatigue tests to certify wind blade and wind turbine designs. In addition to full-scale blade validation, National Wind Technology Center facilities have extensive capabilities to perform small- to large-scale subcomponent tests.
Power Grid Reliability
To characterize wind turbine responses to disturbances on the electric grid, NREL has developed the Controllable Grid Interface (CGI) evaluation system, the first in the United States to include fault simulation capabilities. The 7-megavolt amperes CGI allows manufacturers and system operators to conduct the evaluations required for certification in a controlled laboratory environment. It is the only system in the world that is fully integrated with two dynamometers and has the capacity to extend that integration to turbines in the field and to a matrix of electronic and mechanical storage devices—all of which are within close proximity.
The CGI characterizes wind turbines off-line from the grid, verifies compliance with standards, and provides grid operators with the performance information they need for a fraction of the time and cost it would take to validate a turbine in the field. The CGI is a unique tool for evaluating the frequency response controls of wind turbines and energy storage. In particular, both inertial and primary frequency response controls can be validated and tuned up under real frequency events that can be reproduced on CGI terminals based on previously recorded data from various power systems or from data generated by models.