Upgrades at key SDG&E transmission site improve reliability, reduce energy costs

SAN DIEGO, Nov. 10, 2004 (PRIMEZONE) — San Diego Gas & Electric (SDG&E) recently energized a new 500-kilovolt (kV) switchyard and transformer at its Miguel substation site in Bonita two months ahead of schedule, improving the reliability of the utility’s energy-delivery system and reducing costs for Southern California customers by $18 million annually, according to SDG&E officials.

The project involved building a gas-insulated substation within the existing boundaries of the original substation site, which is the western terminus of the Southwest Powerlink, SDG&E’s only east-west electric transmission corridor. The upgrades were finished in a little more than a year – an unprecedented pace for a project of this complexity, which typically could take as long as two to three years. The accelerated timeframe was possible due to careful coordination between the company and its contractors for “just in time” design, material delivery and construction.

“Completion of the Miguel substation project was a top priority for the company,” said David L. Geier, vice president of electric transmission and distribution for SDG&E. “This project, along with completion of a 230-kV transmission line now under construction from Miguel to our Mission substation, will help improve the reliability of the overall power grid in Southern California. It also will save millions of dollars in energy costs for customers by reducing transmission congestion.”

The project allows SDG&E to import 100 MW to 400 MW more power through the Miguel substation, providing better access to less expensive electricity imports. SDG&E estimates energy cost savings of about $18 million a year by easing the electricity bottleneck at Miguel. Those savings are due to reduced congestion charges and to avoiding the added expense of running older, less efficient local power plants for reliability.

SDG&E pointed out that the $30 million substation project is a cost-effective solution to address the transmission congestion problems that threatened to cause regional outages for Southern California this year.

The substation is a major interconnection between Arizona and California. Regulating agencies, including the Federal Energy Regulatory Commission, the California Public Utilities Commission and the California Independent System Operator, have identified the Miguel substation as one of the most congested intersections on the state’s power grid. As the electricity demand has grown, the power gridlock at Miguel also has gotten worse — like a freeway at rush hour.

“Adding the 500kV switchyard and the second transformer at Miguel is like opening another two lanes on a major highway to allow more cars to use the road,” said Geier. “Nonetheless, you still need adequate on- and off-ramps to improve the traffic flow. That’s the role the second Miguel-Mission 230-kV transmission line would play. That’s why we have asked the CPUC to approve our plan to expedite completion of the line to get it in service as quickly as possible to help avoid outages next summer.”

Unique to the Miguel project is the use of gas insulation in a 500-kV substation. While the technology has been around for some time, this is the first time SDG&E has used it to expand a substation. The novel approach to the project enabled the company to shrink the facility to fit within a fraction of the space usually required.

An air-insulated 500-kV substation typically takes up an area the size of nine football fields, but with the gas-insulated-substation technology, the equipment fits inside a building smaller than one-fourth of a football field. Because it was contained within the substation property’s original “footprint,” the project did not have to go through a lengthy permitting and review process. The gas-insulated-substation design also left room to add more transformers in the future as needed to keep up with demand growth.

“With our innovative approach to the Miguel substation design, we went beyond simply fixing the immediate transmission congestion problem,” said Geier. “We built for tomorrow — to meet future power needs.”

About SDG&E [ www.sdge.com ]

SDG&E is a regulated public utility that provides safe and reliable energy service to 3.2 million consumers through 1.3 million electric meters and more than 800,000 natural gas meters.

The company’s service territory encompasses 4,100 square miles in San Diego and southern Orange counties. Exceptional customer service is a priority of SDG&E as it seeks to enhance the region’s quality of life. SDG&E is a regulated subsidiary of Sempra Energy. Sempra Energy, based in San Diego, is a Fortune 500 energy services holding company.

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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 Jennifer.Runyon@ClarionEvents.com.

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