MW-scale wind turbines provide a testbed for advanced grid integration research and controls system optimization, coupled with energy storage and other advanced technologies. This capability supports the industry trend toward large-scale hybrid wind, solar, and energy storage plants.

The NREL 1-MW/MWh battery energy storage system (BESS) provides as fast as 50 millisecond response times to grid events. The BESS offers a platform for energy storage research and demonstration of improved grid services, including synthetic inertia, fast frequency response, power oscillation damping, active power flow control, reactive power and voltage control, transient fault ride-through, and more. The site also hosts two lithium-ion MW batteries with hosting capacity for four other MW-scale energy storage systems.

Dynamometers validate wind turbine drivetrains by replacing the rotor and blades of a turbine with a powerful motor to simulate operation. They employ model-in-the-loop techniques to emulate rotor, tower, pitch, and yaw systems with computer simulations operating in real time. NREL's 2.5-MW and 5-MW dynamometers can be connected to the CGI for grid integration research, including back to back inverter systems validations.

Advanced sensing, measurement, and forecasting capabilities are incorporated with new generation and load controls to enable advancements in grid operations and controls research. Connection to NREL's High Performance Computing Data Center enables the simulation of massive data flows such as atmospheric inflow, wind turbine loads, electricity generation, and real-time electricity prices to validate new system controls and forecasting over different timescales.

The CGI is a 7-MVA system, with 39 MVA short circuit capacity for 2 seconds, that provides the unique simulation capability of a flexible controlled grid. This capability can be used for validating various types of reliability services under fully controlled grid contingency scenarios and different interconnection conditions, such as strong or weak grids. The CGI enables validation of new grid technologies and control systems, significantly reducing certification time for hardware performance validation 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.

In conjunction with the CGI, researchers use RTDS technologies to simulate regional power flow for actual utility operation including grid-disturbance events, such as a weather-induced outage. RTDS systems enable power and controller hardware-in-the-loop research capabilities, allowing researchers to validate the operation of advanced wind, PV, and energy storage for grid services, including frequency stability, transient stability, and voltage stability. With the CGI and network of installed phasor measurement units (PMU), RTDS systems can conduct power hardware-in-the-loop experiments for large-area stability controls as well as advanced impedance-measurement based stability controls.

High performance computing and visualization at NREL propel technology innovation as a research tool by which scientists and engineers find new ways to tackle our nation's energy challenges—challenges that cannot be addressed through traditional experimentation alone. By including a virtual link from the CGI to the Energy Systems Integration Facility’s HPC systems, researchers and industry partners can visualize complex systems in a virtual environment and observe advanced, real-time testing schemes that combine the flexibility of the CGI with the ESIF’s grid simulator and smart-grid capabilities.

Control of NWTC wind, solar, and energy storage systems are coupled to real-time electricity market price signals to validate system optimization for different electricity markets, including day-ahead energy and ancillary service markets.

The site can connect and disconnect from the utility grid to operate as a microgrid in grid-connected or island mode. In island mode, the site provides its own voltage source, interconnected loads, and variable generation is controlled to maintain stable grid conditions as they act as a single controllable entity with respect to the grid.