NREL researchers develop and test microgrid controls at multiple time scales. This work has been demonstrated via in-house modeling and hardware development as well as testing of partner-developed systems.
A microgrid is a group of interconnected loads and distributed energy resources that acts as a single controllable entity with respect to the grid. It can connect and disconnect from the grid to operate in grid-connected or island mode.
Microgrids can include uncontrollable loads as well as distributed energy resources such as generators, storage devices, and controllable loads. Microgrids generally must also include a control strategy to maintain, on an instantaneous basis, real and reactive power balance when the system is islanded and, over a longer time, to determine how to dispatch the resources. The control system must also identify when and how to connect/disconnect from the grid.
- Modeling and simulation of microgrid systems on timescales of electromagnetic transients and dynamic and steady-state behavior
- Controller hardware-in-the-loop testing, where the physical controller interacts with a model of the microgrid and associated power devices
- Expertise in distributed optimization and control of sustainable power systems that can be applied to microgrid distributed energy resources dispatch
- Power hardware-in-the-loop testing of microgrid hardware
NREL is partnering with the Electric Power Research Institute to validate the performance of a Spirae-developed advanced microgrid controller capable of managing 1–10 MW of aggregated generation capacity. The aim is to develop a commercially viable and flexible microgrid controller that can easily adapt to end-user applications and electric grid characteristics.
The Electric Power Research Institute is leading a team that includes Spirae, NREL, a microgrid system analytics consultant, 14 utilities, and three target communities. NREL’s role is to validate and test the functions of the controller by connecting it to a virtual model of a microgrid embodied within a real-time digital simulator. The controller is also being connected to a utility-scale battery inverter, which interacts with the virtual model through an AC power amplifier and adjusts its output to the simulated electrical grid demand.
In this project, NREL will support GE by installing and testing a GE microgrid controller in a microgrid test platform at the Energy Systems Integration Facility.
This project investigates the interaction of distribution management systems with local controllers, including microgrid controllers. The project is developing integrated control and management systems for distribution systems to address high penetrations of interconnected distributed energy resources. The integrated control will be demonstrated using controller and power hardware connected to a simulation of a distribution system that contains a microgrid.
Omnetric and partners have developed a distributed intelligence platform that can support utility grid and microgrid operations. Power management during microgrid operation is enabled by the Siemens Microgrid Management System. NREL will test the Microgrid Management System performance on a microgrid test platform at its Energy Systems Integration Facility. The platform will include distributed equipment including a microgrid switch, PV inverter, wind power inverter, diesel generator, controllable loads, metering, and a grid simulator to emulate the point of common coupling.
NREL researchers have developed and tested advanced inverter control algorithms that “self-synchronize” when a utility voltage is not present. Under loss of utility power, a microgrid must regulate voltage and frequency within the grid. This research uses virtual oscillator control theory to implement voltage and frequency regulation.