"Then Ben had this idea of having cells that communicate with each other to form a hierarchical system that could cover the entire grid. That's how it went to the multicell perspective."
With the launch of NODES in 2015, Bernstein and fellow NREL Researcher Emiliano Dall'Anese set their sights on new algorithms for a distributed grid. These algorithms use the limited computation of many customer devices such as inverters to functionally run the grid.
"Our main algorithms are coming from optimization and control theory," said Bernstein. "If you go to the literature, there's a gap between the two: Optimization finds solutions (but ignores real-world conditions) while control algorithms work to stabilize in not-ideal conditions. We're bridging the two domains."
"What's novel in our solution is that we address a two-part problem," said Kroposki. "First, because of the large number of devices, we cannot use central control, but must instead distribute the optimization problem. The other problem is that we have time-varying conditions, therefore the optimization is changing every second and must be solved in real time."
Other challenges remain, such as identifying the complete set of inverter functions required to help stabilize the grid, as well as the necessary incentives.
At a theoretical level, AEG stitches these developments together—along with NREL expertise in control technology development, microgrid and distribution system controls, and cybersecurity—into a larger, more complete theory.
Like the grid that the team is optimizing, distributed "cells" of support are appearing for AEG. One of these domains is wind energy, in which an AEG-future also presumes an autonomous wind farm.
"It's one of my favorite projects by far," said Jennifer King, a researcher at NREL who has spent the past year constructing the wind slice of AEG. "It's a nice mix of applied research, but we still get to work at the fundamental, technical level. The techniques and the communication across technologies just don't exist today," she said. "One thought is that buildings can shift their load to try and match (the variable output of wind), so we're working with the buildings team to understand how."