California Center for Sustainable Energy

SDG&E demonstration project in Borrego Springs

In San Diego, electricity meters have become smarter, with two-way communications and real-time monitoring, but the grid that supplies our power needs to be smarter too. That’s the purpose of the smart grid, a sort of Internet for electricity, with controls, computers and equipment working together to respond to quickly changing energy demands. But within the smart grid, there will be even greater need for intricate, local controls - at the microgrid level - a complex challenge for energy managers.

Originated in the 1890s, the electric grid has been improved upon as technology advanced through the decades. Today, it consists of some 10,000 electric generating units, producing more than 4,000 billion kilowatt-hours of power, connected to some 300,000 miles of transmission lines.

The interconnectivity of the power grid is both good and bad - when one distribution point goes down, it can bring on rolling blackouts and other distribution irregularities. With the advent of microgrids, the electric industry in the U.S. is on the brink of making a transition from a centralized system to one that is less centralized, more interactive with community demands and capable of continued supply even when other parts of the grid are shutdown, according to Vic Romero, director of smart grid projects for San Diego Gas & Electric. Romero gave a workshop on microgrids at CCSE in June.

Smart Grid: An intelligent distribution network that, using digital technology, delivers electricity from suppliers to consumers. This technology improves the grid’s efficiency and reliability by automatically alerting of power outages and by using two-way communications combined with smart meters, allowing customers to control and reduce their energy use.

Microgrid: A group of interconnected loads and distributed energy resources within clearly defined electrical boundaries that acts as a single controllable entity with respect to the grid. A microgrid can connect and disconnect from the grid to enable it to operate in both grid-connected or island-mode.

In October 2009, California established the deployment of smart grid technology as policy, requiring state utilities to submit a smart grid plan to the Public Utilities Commission by July 1, 2011. In June, San Diego Gas & Electric ( SDG&E) filed their smart grid deployment plan as a “policy guide for future investments” based on continuing dialogue with regional stakeholders and increasing customer needs for interconnecting renewable energy sources, powering electric vehicles and other technologies.

As part of efforts to help develop a smart grid, SDG&E is creating a demonstration microgrid project of sensors, communications and control equipment in Borrego Springs, a $15.2 million project with funding from the Department of Energy and the California Energy Commission. It is one of only nine DOE-funded microgrid projects nationwide.

The Borrego substation, with a peak load of over 10 megawatts, was selected because it provides a unique opportunity to explore microgrid islanding of an entire substation service area. SDG&E will test if they can keep the area running when disconnected from other parts of the grid.

The project involves integration of five technologies, including renewable energy resources and energy management, feeder automation system technologies, advanced energy storage, an outage/distribution management system and price-driven load management. The project will proactively identify and apply leading-edge technologies to improve the security and reliability of electricity supply and to lower costs to consumers.

"In addition to microgrid technology, the Borrego Springs project will teach us about numerous technologies, from battery storage and fuel cells to balancing load on a circuit-by-circuit basis," Romero said. "This technology has the potential to lead to greatly increased reliability."

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