Power Cut Off to 35,000 in Southern Arizona
Jun 18 - Arizona Daily Star
Arizona's Palo Verde nuclear power plant - the nation's largest single producer of electricity - may remain out of service for days after a glitch in the region's electrical grid triggered an automatic shutdown Monday morning.
Lights, computers and air conditioners were simultaneously knocked out for
about 35,000 Tucson Electric Power Co. customers in Tucson and Green Valley,
plus an additional 30,000 Phoenix-area residents. Power was restored to
virtually all customers within an hour.
Utility officials said the outage at Palo Verde, 55 miles west of Phoenix,
didn't put the public at risk. They also said it shouldn't have any lasting
effects on Arizona's power supply or the rates customers pay.
"Essentially, what we saw was the system protecting itself. . . . It was
a very orderly shutdown," said Jim McDonald, spokesman for Arizona Public
Service Co., which owns a 29.1 percent share of Palo Verde and supplies power to
about 1 million Arizonans, most of them around Phoenix.
The outage also hit APS' Redhawk natural gas power plant, five miles
southeast of Palo Verde, and the nearby Arlington Valley natural gas plant run
by Charlotte, N.C.-based Duke Energy North America. Those two facilities quickly
restarted, but APS officials said it probably would take days for the Palo Verde
plant to return to normal.
Although about 65,000 Arizonans lost power at the start of a hot summer day,
energy companies and state regulators said the system worked, since it didn't
fall prey to a massive, cascading blackout like the one last August that
afflicted nearly 50 million residents of the Northeast and Midwest.
"It was not a significant outage in terms of the size, scope and
duration of it," said Heather Murphy, spokeswoman for the Arizona
Corporation Commission, which regulates utilities. "There's nothing that
indicates to the commission that we have a systematic grid problem, the likes of
which they had back East."
Since 2000, Arizona has added more than 9,000 megawatts of generating
capacity and also upgraded its transmission network, Murphy said.
"With all the additional generation that's available in and around
Arizona, I believe the power is out there for us to keep the lights on and not
have any additional problems," she said.
Palo Verde, built at a cost of $5.9 billion, supplies 3,810 megawatts to
about 4 million customers in Arizona, New Mexico, Texas and California. TEP is
not a regular Palo Verde customer, relying instead on its own generating
stations in Tucson, Springerville and the Four Corners area.
"We're connected to them via the grid, but TEP doesn't own any of the
Palo Verde facility," said Art McDonald, a TEP spokesman. "We may have
purchased power coming out of Palo Verde in the past to supplement our own
system, or if market conditions were economically advantageous."
APS will be forced to buy replacement power, but that added expense will be
borne by the company's shareholders, not its ratepayers, APS' McDonald said.
The problem began at 7:41 a.m. when a disturbance on the grid cut power to
the northern and western sections of the Phoenix metro area.
"Something, somewhere in northwest Phoenix went wrong with the
wires," APS' McDonald said. "We don't know where, don't know why or
know how."
The disturbance may have been centered on non-APS equipment near 115th Avenue
and Union Hills, he said.
Because of the sudden loss of generating capacity on the grid, about 35,000
TEP customers scattered around the metro area went dark as computers sought to
rebalance the system.
"Power is generated as needed. It can't be stored," TEP spokesman
Joe Salkowski said. "At any given moment, there is an equal amount of power
being generated and used."
The power disruption caused TEP to lose about 60 megawatts when the load on
the system was 1,040 megawatts. At this time of the year, TEP's demand peaks at
about 1,800 megawatts in the late afternoon.
Palo Verde
Palo Verde Nuclear Generating Station
Operator: Arizona Public Service Co.
Owners:
APS 29.1%
Salt River Project 17.5%
El Paso Electric Co.15.8%
Southern California Edison 15.8%
Public Service Company of New Mexico 10.2%
Southern California Public Power Authority 5.9%
Los Angeles Department of Water and Power 5.7 %
Capacity: 3,810 megawatts from three 1,270-megawatt units
Construction: Began June 1976. Unit 1 completed January 1986, Unit 2 in
September 1986 and Unit 3 in January 1988. Total cost: $5.9 billion.
Source: Salt River Project
Contact reporter Mitch Tobin at 573-4185 or mtobin@azstarnet.com
. Star reporter Jennifer Sterba contributed to this story.