NREL's controllable grid interface test system can reduce certification testing time and costs while providing system engineers with a better understanding of how wind turbines react to disturbances on the electric power system.
To understand the behavior of wind turbines during grid disturbances, manufacturers and utility grid operators perform a series of tests and transient simulation studies. Utility operators need to estimate how much power wind turbines can provide to help regulate grid frequency. And after design modifications are made to control software, manufacturers may need to retest their turbines. But testing wind turbines in the field can be a lengthy and expensive process.
NREL developed the controllable grid interface (CGI) test system to reduce the time and cost required to conduct these tests. The controllable grid interface is the first test facility in the United States that has fault simulation capabilities. It allows manufacturers and system operators to conduct the tests 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. NREL's 7-MVA CGI tests 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 test a turbine in the field. CGI is a unique tool for testing frequency response controls of wind and solar generation and energy storage. In particular, both inertial and primary frequency response controls can be tested, 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.
For More Information
For more information about grid simulation, see the following resources.
First International Workshop on Grid Simulator Testing of Wind Turbine Drivetrains
NREL and Clemson University hosted the First International Workshop on Grid Simulator Testing of Wind Turbine Drivetrains June 13–14, 2013, at the National Wind Technology Center near Boulder, Colorado.
Second International Workshop on Grid Simulator Testing of Wind Turbine Drivetrains
NREL and Clemson University hosted the Second International Workshop on Grid Simulator Testing of Energy Systems and Wind Turbine Powertrains at the Duke Energy Electric Grid Research, Innovation & Development Center in North Charleston, South Carolina September 17–18, 2014.
NWTC Controllable Grid Interface
This fact sheet explains NREL's controllable grid interface, which tests wind turbines off-line from the grid and verifies compliance with standards.
Grid Simulator for Testing MW-Scale Wind Turbines at NREL
This poster describes an initiative by NREL to design and construct a 9-MVA grid simulator to operate with 2.5-MW and 5-MW dynamometer facilities.