It all happened within three minutes. At 1:08 p.m. Tuesday, a West Dade substation caught fire. A disconnect switch should have shut down the site, but for reasons unknown, the switch failed and the problem spread.
Next, the two huge nuclear reactors at Turkey Point sensed something was wrong and automatically shut down to protect themselves. Then, Florida’s entire grid started turning off lights because there wasn’t enough power.
This is Florida Power & Light President Armando Olivera’s explanation of how an estimated million customers statewide lost power. One switch didn’t disconnect like it was supposed to, and much of the electrical grid was down in a flash.
”That’s the part we don’t have any explanation for,” he said.
In fact, what occurred Tuesday isn’t that unusual. An outage large enough to darken at least half a million homes happens about every four months, according to a 2004 report from Jay Apt, an electrical reliability expert at Carnegie Mellon University.
NOT SINGLE PROBLEM
And that, Apt noted, is a function of the state of the United States’ power infrastructure. The system, he says, is designed to easily adjust itself to a single problem. More than one problem? Lights start blinking out.
”The North American Reliability Council says you have to be able to live with a single outage,” Apt said.
Much of the developed world does much better. Reported Apt in Issues in Science and Technology in 2006, the ”average U.S. customer loses power for 214 minutes per year. That compares to 70 in the United Kingdom, 53 in France, 29 in the Netherlands, six in Japan and two minutes” in Singapore.
Tuesday’s outage also reflects the system’s complexity, said Wade Troxell, an engineering professor at Colorado State. “The electric power grid is like the world’s most complex machine. No one person or entity controls or operates it. It operates much like a living organism.”
On Tuesday, the problem began at the Flagami substation on Flagler Street at 92nd Avenue, an unmanned structure of power lines and boxes across the street from FPL’s Miami-Dade headquarters.
Something sparked a fire. Such incidents happen all the time. A breaker, which can be 10 feet long, shuts down the station, and the grid is programmed to automatically adjust so that few, if any, customers lose power.
”These systems are all designed to handle two contingencies,” said Olivera. On Tuesday, that didn’t happen. ”We still don’t have a full understanding of what happened,” he said.
When the breakers didn’t isolate the problem, it spread quickly to other substations, perhaps as many as 20. At that point, ”a variety of sensors” at Turkey Point realized something was wrong, said Art Stall, FPL’s chief nuclear officer. “They acted to isolate it from the grid.”
The U.S. Nuclear Regulatory Commission hasn’t yet measured the duration or degree of the grid disturbance, but the voltage blip was enough to trigger an emergency shutdown of both nuclear reactors at Turkey Point, as well as three other units — instantly unplugging a plant that supplies nearly a half-million homes.
”We may be talking about a few seconds that caused this to happen,” said Roger Hannah, a U.S. Nuclear Regulatory Commission spokesman.
Though Turkey Point is South Florida’s largest source of electricity, it depends on off-site power to run most of its critical safety systems, such as pumps and circulating systems that cool the reactors and a stockpile of spent nuclear fuel.
That’s a standard safeguard to ensure plant operators can still shut down a reactor if the plant suffers a problem, Hannah said. Turkey Point, like other plants, also has an array of diesel backup generators if off-site power fails.
AUTOMATIC RESPONSE
FPL said Turkey Point never lost its off-site power, but at 1:09 p.m., the plant’s sensors detected a drop in voltage in transmission lines serious enough to trip an automatic shutdown. Electromagnets opened, dropping control rods over exposed uranium in the reactors and halting the nuclear fission that superheats water used to turn the steam-driven turbines.
”It’s almost instantaneous,” said April Schilpp, FPL’s senior manager for nuclear communications. “When it’s automatic like that, the turbines go off-line and everything goes boom-boom-boom in sequence.”
It’s something akin to the way a household circuit-breaker works, though those are designed to respond to damaging surges of excess power, not threatening drops in voltage.
The two reactors at Turkey Point — as well as a new natural-gas fired generator at the same location — shut down within a minute. That was an intense shock to the electric system — creating far more demand for power in the area’s homes and businesses than there was supply.
To fix that imbalance, the system automatically shut down large parts of the grid, the effects rippling up the state in waves of brownouts and blackouts.
About 196,000 customers in Miami-Dade and Broward lost power, 168,000 in Palm Beach County, 91,000 in Naples and elsewhere in Southwest Florida, and 18,000 in the Daytona area.
Because the grid connects all Florida utilities, Progress Energy Florida, which operates in the central part of the state, had 153,000 customers lose power. Tampa Electric reports about 80,000 customers were affected, mostly in Hillsborough County.
1 MILLION AFFECTED
Altogether, Olivera estimated 1 million customers in the state lost power at one point or another.
By 3 p.m., less than two hours after the initial problem, most of the customers in central Florida had their lights back. By 5 p.m., only about 8,000 FPL customers were still in the dark.
In the infamous blackout of 2003, which stretched from Ohio to New York, a task force blamed the disaster on human error. On whether that was a possibility Tuesday, Olivera said, “I wouldn’t rule out anything right now.”
When asked later how often the disconnect switches are inspected and when they were last inspected, the utility did not have an immediate reply.
Experts say there are other ways to operate an electric grid. Apt, the Carnegie Mellon professor, noted that after France experienced severe outages in the late 1990s from ice storms, “it just built double lines that were tremendously expensive.”
Because France has a single, government-controlled grid, it could do that ”by fiat,” Apt said. In the United States, that might double the cost of electricity, which neither utilities nor customers are eager to see.
Troxell, the Colorado engineer, said some countries are now building a ”smart grid,” which is less centralized and a greater diversity of power makers, such as solar units in homes. “That helps manage the system to prevent cascading from happening.”
Both FPL and NRC said Turkey Point’s automatic safety systems worked as designed and federal site inspectors reported no indication of problems with the reactors, said Ken Clark, a Nuclear Regulatory Commission spokesman.
But critics said the outage underlined their concerns about FPL’s plans to add two more reactors at Turkey Point in coming decades.
Dawn Shirreffs, South Florida Organizer for Clean Water Action, said Florida’s Public Service Commission should push for safer alternative sources less vulnerable to minor outages.
”The domino effect that occurred in today’s blackout would not have occurred using a variety of real clean energy solutions,” she said.
Source: Miami Herald
*Sigh* I wish that newspapers and television stations didn’t feel obligated to get quotes from self-proclaimed “experts” blithely claiming that “clean electrical solutions” should be used to solve the problem. Like what, damnit? If there were an “alternative” “clean” method of generating power that was affordable, (oh, no! Not the dreaded “a” word!) it would already be in use. Putting $100,000 worth of solar panels on a roof that might sail over to the next county in hurricane season seems, to put it mildly, really stupid. Something tells me that she isn’t championing small neighborhood pellet bed reactors.
I suppose she wants us to drain the ‘glades and plant ’em in sugar cane to make ethanol which doesn’t seem very environmentally sound but hey, it works for me. I’m not that fond of skeeters and gators anyway.
A1A South 