NREL, SDG&E collaboration expands resiliency in Borrego Springs

Some of the United States’ most beautiful and geographically diverse locations are also marked by extreme weather occurrences, which can create disturbances on the electric grids that supply them with power. Borrego Springs, California, is one of those places.

Borrego Springs is northeast of San Diego—and to help address the high-risk environment, San Diego Gas & Electric Co. (SDG&E) operates a microgrid there. In collaboration with the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL), SDG&E is able to remain on the forefront of advanced microgrid technology.

Microgrids are self-powered electric grids that can operate independently or connect to the larger grid. They play an important role in resiliency, in part, because they are able to disconnect from the main grid during outages and continue to operate independently. Energy resiliency in places such as Borrego Springs is especially important.

“Borrego Springs is on the eastern edge of our service territory,” said Tom Bialek, SDG&E chief engineer. “You get these monsoonal rains that occur and cause flash floods, and there’s a lot of talk in our region on energy resilience because we’re in an area that faces significant wildfire threats. Due to our complex topography and strong Santa Ana winds, San Diego and Southern California are the most conducive to rapidly expanding wildfires anywhere in the United States and perhaps the world. These winds get to be hurricane force. That’s what people don’t appreciate. We’re looking at Category 1 to Category 2 winds down over the mountaintops coupled with low humidity and dry, dead fuel. In this environment, all it takes is a single spark and fires will spread very, very quickly. From a resiliency perspective, that’s why this is really important.”

What NREL is working with SDG&E to better understand is how a microgrid controller with advanced technology would perform, specifically with the Borrego Springs microgrid. NREL is able to explore this safely at its Energy Systems Integration Facility (ESIF), which is home to an important and unique capability. The ESIF houses NREL’s megawatt-scale microgrid test platform, which allows utilities such as SDG&E to connect their microgrids and run a variety of simulations.

“We have an amazing modeling and simulation capability to bring in feeder data from SDG&E and be able to answer “Ëœwhat if’ questions with multiple devices, not just with a single component, utilizing our power hardware-in-the-loop capability,” said Martha Symko-Davies, Energy Systems Integration laboratory program manager. “That’s the key of what ESIF can do: de-risk and implement the technology in Borrego Springs.”

Annabelle Pratt, NREL principal investigator on the project from the Power Systems Engineering Center, said collaboration was key to this project. NREL had to obtain the modeling data from SDG&E to set up the simulation. NREL also needed the controller. For this project, Pratt, Kumaraguru Prabakar, and the rest of the team had controller hardware and two megawatt-scale inverters in the loop.

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The Clarion Energy Content Team is made up of editors from various publications, including POWERGRID International, Power Engineering, Renewable Energy World, Hydro Review, Smart Energy International, and Power Engineering International. Contact the content lead for this publication at

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