San Diego Gas & Electric (SDG&E) has continued to utilize their microgrid in the Borrego Springs community and, in May, had to use it to power the entire community during a planned grid outage. According to SDG&E, it is believed to be the first time in the country that a community has been fully powered by a microgrid system.
The utility said that, in addition to on-site generation and energy storage systems, they also used a nearby 26 megawatt (MW) NRG Energy solar facility to supply electricity to the area's nearly-3,000 people.
The Borrego Spring Microgrid was integrated after SDG&E received an $8 million U.S. Department of Energy (DOE) grant in 2008.
"SDG&E demonstrated in a real-world situation how we can use innovative technology to create a more resilient and sustainable grid for our customers," said Dave Geier, SDG&E's vice president of electric transmission and system engineering, in a statement. "Borrego Springs was entirely separated from the main grid, running on the Microgrid's local onsite resources for nine hours as we conducted necessary maintenance. This ability to operate independently of the grid when necessary is exactly what the Microgrid was designed for and the fact that we were able to accomplish this using local renewable energy is an added benefit. We are very proud to offer this innovative service to the community."
The maintenance needed on the microgrid was caused by a lightning strike that had damaged a transmission line feeding Borrego Springs. The repairs included work on three transmission poles -- a repair that would normally cause a 10-hour outage to the community. Borrego Springs' microgrid uses a combination of local power generation, energy storage, and automated switching, which can allow it to disconnect from the San Diego Grid during emergencies.
"SDG&E seamlessly switched over to the Microgrid to power the entire community at 8:45 a.m. on May 21, allowing the maintenance work to begin," the utility said in a statement. "The Microgrid generated the majority of power during this time from the large Borrego Solar facility, using batteries and traditional distributed generation to 'follow the load' and fill in gaps created by the solar facility. This is necessary because solar power is intermittent by nature and requires back-up resources when solar becomes unavailable, such as when a cloud moves in front of the sun."
The microgrid is powered by computer software and automated switching that helped any fluctuations be accounted for in real-time. The grid maintenance was finished at 5:30 p.m., when SDG&E switched the community back to the main grid. Customers saw a 10-minute planned outage, rather than the nine hours they could have been without power.
"The Microgrid was really a crucial tool during this maintenance," said Linda Haddock, executive director of the Borrego Springs Chamber of Commerce, in a statement. "This innovative project provided electricity to our residents and kept the town running all day. Residents were also pleased that the Borrego Solar facility was used to support this effort. It's great to see all these local, sustainable resources being put back into the community to truly make a difference in the lives of our residents in Borrego Springs."
SDG&E was recently awarded another $5 million from the California Energy Commission (CEC) to connect the nearby solar facility to help power the entire microgrid -- which adds even more reliability of the grid.
"SDG&E's success during the outage is the first step in implementing the CEC's grant. SDG&E plans to incorporate more advanced computer software and sensors to continue to enhance the microgrid," SDG&E said in a statement. "These innovations will broaden the microgrid's use of renewable energy to power the entire community and allow this type of outage response to become routine and standardized."
The construction on the new integration is expected to be completed by mid-2016.
Source: Smart Grid News
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