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Controllable Grid Interface Test System

NREL's controllable grid interface (CGI) test system can reduce certification testing time and costs while providing system engineers with a better understanding of how wind turbines, photovoltaic inverters, and energy storage systems react to disturbances on the electric power system.

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 devicesall of which are within close proximity.

NREL's 7-MVA CGI tests wind turbines offline 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.

The CGI test system is located at the National Wind Technology Center.

Download the fact sheet.


Vahan Gevorgian

Senior Engineer | 303-384-6940