To provide a stable electric power supply and meet the burgeoning demands of the 21^st century, Stanford University (Palo Alto, California, U.S.) recently upgraded its primary distribution substation and reconfigured controls to enable a power island via the existing campus cogeneration system.

Located beside Palo Alto in the San Francisco Bay area, Stanford University is a highly developed and complex campus with facilities and services far more elaborate and strategic than those of the typical community of 13,000.

The ever-mounting electric energy needs of “The Farm,” as the 8200-acre (3318-hectares) Stanford campus is known, include providing for a vigorous real estate development plan. There are 678 major buildings at Stanford, plus 843 owner-occupied housing units for faculty on campus, and 628 rental units. The local county Board of Supervisors has approved a new 10-year university General Use Permit and Community Plan allowing for 2 million additional square feet of academic facilities and up to 3000 new housing units to be built on campus. When the plan is fully implemented, The Farm will house thousands of buildings and an even higher population of users who will be highly dependent on reliable electric power.

A 50-MW gas and steam turbine cogen system, operated by Cardinal Cogeneration, meets much of the university's present power needs, and also sells power back to the general grid via Pacific Gas & Electric Co. (PG&E), backfeeding an average of approximately 20 MW. The faculty residential area is served by PG&E.

Glyn Lewis, partner and design engineer for Applied Power, a Redwood Shores, California, U.S., electrical engineering consultant, was hired by the Stanford High Voltage Shop, which runs the Electrical Power System, to perform a peer review of the substation in 2002. Lewis and the High Voltage Shop organization decided that much of the main substation's hardware would have to be replaced or upgraded to meet future goals. Also, the Utility Group needed to modify relay protection and communications to implement the power island. The project team divided the work into two phases, and Lewis was retained as a consulting engineer for the project.

Phase One began with replacement of the substation circuit breakers and disconnect switches. “The circuit breakers had to be replaced. They were 50 years old, and there were no spare parts available anymore,” Lewis explains. “Secondly, the Utility Group was experiencing trouble with the high-voltage disconnect switches, so they wanted to have those replaced for reasons of safety as well as reliability.”

“We split the substation so that we'd have most of it operating during the upgrade,” says Steve Briscombe, Stanford Electric utility manager. “We decommissioned one side of the bus and replaced the protection relays, then finished up on the other side. This approach enables us to accomplish the whole project without shutting down university facilities.” The old 60-kV oil-filled circuit breakers (OCBs) were removed from the substation, and replaced with SF6 breakers.

The new relays include the SEL-351 directional and overcurrent reclosing relay, SEL-311 Series relay, SEL-551 overcurrent/reclosing relay, and SEL-587 current differential relay. There are also redundant SEL-2100 logic processor units to apply the SEL logic and communications. SEL-2505 remote I/O modules handle the fiberoptics link for remote control from the cogeneration plant, which is 2000 ft (607 m) away from the control room.
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