Controllable Grid Interface

NREL uses its controllable grid interface (CGI) to recreate any grid scenario to better understand impacts on energy systems and grid-edge devices.

The CGI allows researchers to customize power in multimegawatt experiments. This is used to demonstrate controls and configurations for wind and solar power generation, energy storage systems, conventional generation, and diverse loads.

Growth in renewable energy introduces new operational challenges to the power sector. Wind, solar, and battery power plants must comply with strict grid interconnection rules, including fault ride-through, power quality performance, and the provision of essential reliability services for grid operations. To validate these services and device controls, the industry needs a tool to replicate power systems in a safe environment.

The CGI at NREL comprises two systems, 7 MVA and 20 MVA, that can validate the many active and reactive power control features of renewable and conventional generation and storage technologies in a controlled, 13.2-kV, medium-voltage grid environment. The CGI can validate:

• Direct frequency control (for islands or microgrids)
• Black-start capability
• Voltage fault ride-through, in accordance with grid codes and standards
• Inertial response (synthetic synchronous inertia)
• Fast frequency response
• Primary frequency response controls (governor droop-like control)
• Harmonic injections
• Reactive power controls under weak and strong grid conditions
• Balanced and unbalanced fault ride-through of devices under simulated grid conditions
• Advanced controls testing, such as interarea oscillations damping controls, sub-synchronous control interactions, damping controls, impedance characterization of inverter-based technologies, other plant-level controls using RTDS/HIL for larger plant simulation, and microgrid/islanded grid energy management systems testing.

Publications

NREL CGI and Power-Hardware-in-the-Loop Platform for Validation of Multi-Technology Energy Systems at Scale, Presentation at the Sixth International Workshop on Grid Simulator Testing of Wind Turbine Power Trains and Other Renewable Technologies (2022)

Stability and Fidelity of Power-Hardware-in-the-Loop Using NREL’s CGI, Presentation at the Sixth International Workshop on Grid Simulator Testing of Wind Turbine Power Trains and Other Renewable Technologies (2022)

Overview of ARIES Research Projects Involving Inverter-Based Resources, Presentation at the Power Electronic Grid Interface Platform Workshop (2020)

NREL Controllable Grid Interface (CGI): Overview of Progress and Projects, Presentation at the Fifth International Workshop on Grid Simulator Testing (2019)

Overview of CGI/Dynos/PHIL Platform, Presentation at the Fifth Annual International Workshop on Grid Simulator Testing of Energy Systems and Wind Turbine Powertrains (2018)

View all NREL publications about the controllable grid interface.

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