A transformer exploded last October at the National Renewable Energy Laboratory’s Flatirons campus in Colorado, cutting off the lab’s connection to the grid and shutting down NREL’s offices, servers and research hardware.
But the lab was surrounded by the solar panels, wind turbines and batteries it studies. It just lacked a controller that would have coordinated those assets to produce a reliable microgrid.
"When the Flatirons Campus lost power, we didn't have a microgrid controller capable to black start and manage all the microgrid assets, and building a controller from scratch was impractical with such short notice," said Przemyslaw Koralewicz, an NREL researcher.
Instead of using a controller to connect components, the researchers programmed each one individually to promote stability.
“We developed a communication-less scheme that took advantage of standard frequency controls of the renewable assets and that could be programmed expediently without significant oversight or customization," Koralewicz said.
This improvised scheme proved to have a number of advantages over microgrid controllers, he said.
"For one, the cybersecurity threats directed at distributed resources become effectively zero, because data exchange between devices isn't necessary. Additionally, the approach is plug and play for devices, such that renewable assets can be added or removed more-or-less seamlessly."
This makes it scalable, according to NREL, to much larger applications like the Hawaiian islands or the Western Interconnection that spans the western continental states.
The blackout changed the way researchers approach the Advanced Research on Integrated Energy Systems (ARIES) program, which is designed to match the complexity of the world’s energy system. They have since used a 1.5 megawatt wind turbine, a 450 kilowatt solar panel array, and a 1 MW lithium-ion battery to keep the lab running—reliably—for 72 hours.
For the researchers, their experience has resolved doubts about the resilience of a 100%-renewable system.
“Our results with ARIES show there is nothing to fear from a fully renewable grid,” the lab asserts.
Read more analysis on how the scheme promotes resilience here, or watch this newly-released video overview: