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Unusual Outage Tests Power Grid

Tribune photo by MICHAEL SPOONEYBARGER

Crews with Progress Energy worked on power lines along U.S. 19 just south of Enterprise Road in Palm Harbor Tuesday.

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By RICHARD MULLINS, The Tampa Tribune

Published: February 27, 2008

An extraordinary loss of electricity from two South Florida nuclear power plants about 1 p.m. Tuesday triggered a cascade of blackouts across the state, cutting electricity for an estimated 3 million people.

Within a few seconds of the nuclear units going down, electrical networks from Miami to Tampa engaged safety systems to protect themselves from potential damage and stopped providing electricity to customers, power company officials say.

The outage affected several hundred thousand customers in the Tampa Bay area for several hours Tuesday.

The statewide event may have been triggered by a fire at an electrical substation in Miami, illustrating the interdependent nature of electricity distribution in Florida. If anything, the outage put emergency backup systems to the test at phone, cable, cellular and other utility providers that normally only engage those systems during hurricanes.

"This was an extremely unusual occurrence," Tampa Electric Co. President Chuck Black said.

About 50,000 of Tampa Electric's 670,000 customers lost power for some time Tuesday. Most customers saw service restored by 4 p.m., company officials said.

About 150,000 Progress Energy customers across the state lost power. The company did not have a tally of local outages but said the vast majority had power restored by 3 p.m.

Florida Power & Light, the state's largest utility, said equipment failure and a fire at a Miami substation led to the power outage. FPL is still trying to determine what caused the failure and fire. The company says such equipment failure should not have caused the widespread blackouts.

The outages had no connection to terrorism, Homeland Security Department spokeswoman Laura Keehner said. No foul play was suspected, Miami-Dade County Mayor Carlos Alvarez said.

Florida Gov. Charlie Crist said that he was grateful to the utilities "for the great work they put in" to quickly restore power.

Crist said he consulted with Florida National Guard Maj. Gen. Douglas Burnett about using troops to help ensure the safety of Floridians in case it appeared there would be significant outages overnight, but Crist ruled out troop use when power was restored for most customers by nightfall.

Rapid Fire Chain Of Events

The power disruption in Miami rippled across a large, cooperative power grid that connects Florida power plants and is designed to routinely smooth out lulls and spikes in power usage and demand.

The outage began when a Florida Power & Light electricity distribution system in the Miami area broke down about 1 p.m., said Brenda Mozafari, a project manager with the Nuclear Regulatory Commission who oversees projects at Florida nuclear plants.

When that outage occurred, two nuclear generating units about 25 miles south of downtown Miami at Turkey Point independently and automatically unplugged from the power grid, shutting down to prevent internal damage.

Within a couple of seconds, control rods above the two Turkey Point reactor cores dropped down between the nuclear fuel rods - as they are designed to do - all but instantly squelching the nuclear chain reaction that helps generate electricity, NRC officials said.

It's thought the reactors sustained no damage.

As the nuclear plants stopped producing power, the overall electricity supply dropped dramatically across the state. That, in turn, triggered safety systems to engage as far away as Tampa and Gainesville.

Two other nuclear power plants in the state, a reactor in Crystal River and twin reactors in St. Lucie County, continued to operate, although officials at those two facilities noticed the grid disturbance.

One nuclear unit at Turkey Point was set to restart Tuesday evening. The other was expected to remain shut down for scheduled maintenance, NRC officials said.

System Worked On Cue

Although inconvenient to customers, the outages in the Bay area occurred because electrical systems did what they were designed to do, Tampa Electric Co. officials said.

The phenomenon is similar to a home surge protector for TV sets or computers, which automatically cuts the power flow when it detects a disturbance. By doing this, it is hoped that damage to a TV or computer is prevented. The surge protector can be reset quickly when the power supply stabilizes.

"By disconnecting, we prevented something that could have moved into a much worse problem," said Black at Tampa Electric.

Normally, Florida's statewide electrical grid handles power loss and spikes several times a day, balancing demand and generation from power plants across the region with no effect on customers. The difference Tuesday was the degree of the problem, Black said.

Although the exact scope had not been determined, power experts said the system immediately lost between 2,000 and 3,000 megawatts, the equivalent of two or more large power plants.

Black said such a sudden, large drop in power had not happened in recent memory, outside of hurricanes in Florida.

Local Ripple Effect

Tampa Electric spokesman Rick Morera said most of the large-scale outages in the Tampa area affected New Tampa and the University of South Florida's Tampa campus.

The Brandon and Valrico areas east of Tampa lost power for about 45 minutes, coming back up shortly before 2 p.m. Neither Brandon Regional Hospital nor the Westfield Brandon mall reported power outages. Hospitals typically have emergency generators to keep critical systems running.

At Tampa's University Community Hospital, an operations building and a warehouse, neither of which is directly involved in patient care, lost power for about 50 minutes.

In Pinellas County, about six schools reported power losses, school district spokeswoman Andrea Zahn said. Outages were also reported at the school district's administrative offices, transportation facilities and operations offices.

The power loss resulted in traffic signals going dark in some areas across Tampa.

Phone and cable TV companies in the Bay area engaged backup systems normally used only during severe storms. By 2:30 p.m., Verizon Wireless officials counted 61 cellular phone sites in the Tampa Bay area running on backup generators and 24 sites on battery backups. None of those cellular sites lost service, said spokesman Chuck Hamby, even though the company saw a "tremendous amount of usage all of the sudden as people reached for their cell phones."

The main land-line phone company in the area, Verizon, reported some service problems in the Brandon area as backup generators turned on, spokesman Bob Elek said. The company's Internet and FiOS TV service also saw battery backup systems engage at homes.

Bright House Networks had brief glitches, spokesman Joe Durkin said, but a backup system restored power for cable TV, phone and Internet service.

Information from The Associated Press was used in this report. Reporters from The Tampa Tribune, TBO.com and News Channel 8 also contributed. Tribune reporter Richard Mullins can be reached at rmullins@tampatrib.com or (813) 259-7919.

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