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(回答先: エリー湖周辺で電流が逆流 投稿者 エイドリアン 日時 2003 年 8 月 16 日 20:08:42)
Investigators focused on an electrical transmission loop that encircles Lake Erie as they tried to understand a massive power blackout that cut across the Northeast and Midwest, leaving millions of people without electricity.
Although no cause has been determined, officials were taking particular interest in a series of power line interruptions that occurred in the Cleveland area during the hour before the blackout hit Thursday, racing across the region from southern New England to Michigan.
Two minutes after the last of these Cleveland-area line problems there were "power swings noted in Canada and the eastern U.S.," said a document made public late Friday by the North America Electric Reliability Council.
But the NERC document cautioned "it's not clear if these events caused the (wider blackout) or were a consequence of other events."Public Utilities of Ohio Chairman Alan Schriber said that the information from NERC was inconclusive but that "it's in the realm of possibility" that power was being drawn from FirstEnergy from outside its system because of increased power demand."Everybody's trying to point their finger at Ohio. By golly, maybe it's not Ohio," Schriber said. "I don't know who that would be and they (NERC) don't either."Meanwhile, the White House announced a U.S.-Canadian task force will investigate the cause of the blackout and identify actions to prevent it from happening again. It will be headed by Energy Secretary Spencer Abraham and Canadian Natural Resources Minister Herb Dhaliwal.
President Bush said the power breakdown showed "we need to modernize the electricity grid." But, he acknowledged, "Something like this isn't going to happen overnight."NERC officials also said that as of late Friday afternoon about two-thirds of the lost power had been restored throughout the affected region. At the peak, 61,800 megawatts of power had been lost; by 4:15 p.m. Friday all but 19,900 megawatts had been restored, said NERC. It gave no breakdown on what areas were still without power.
The cause of the blackout remained elusive. Earlier it had been believed the problem started in Canada, while still another theory had the cause pinned down to eastern Michigan.
No one was sure.
What did become clear, however, was that power grid experts were stunned at the broad reach of the blackout and the speed - a matter of seconds - in which it spread thousands of miles across New York and southern New England to the eastern sections of Michigan and into Canada."We never anticipated we could have a cascading outage" of this magnitude and speed, said Michehl Gent, chief of NERC, the industry-sponsored organization charged with assessing the dependability of the nation's electric grids.
Precautions were supposed to have been put in place to prevent such a widespread domino effect, he said, vowing to ferret out what triggered the chain of events and to take corrective action.
If the problem began in Ohio or Michigan, as was being speculated, it should never have reached Manhattan, complained New York Gov. George Pataki, adding that the grid was supposed to be designed to isolate such problems. "That just did not happen," he said.
But it may be days, even weeks, before solid answers emerge.
As power slowly began to be restored Friday, officials jumped from one theory to another in search for a cause.
Gent at a news conference acknowledged that the answer was somewhere on what is called the "Lake Erie Loop" - a massive, but troublesome transmission loop that encircles Lake Erie from New York to Detroit, into Canada and back to New York."That's the center of the focus. This has been problem for years and there have been all sorts of plans to make it more reliable," said Gent.
About the time power was disrupted at 4:11 p.m. EDT Thursday, technicians noticed a stunning development on the northern leg of the loop: some 300 megawatts of electricity moving east abruptly reversed course and within seconds 500 megawatts of power suddenly were moving west.
Electricity flows on its easiest path so it is believed the change in direction was caused by a sudden reduction in power somewhere on the line at the western end of the loop, investigators suggested."This was a big swing back and forth," said Gent, adding that throughout the grid system, power levels began to fluctuate. That caused generators and other systems to trip across the region to protect equipment.
More than 100 power plants, including 22 nuclear reactors in the United States and in Canada, shut down, most of them automatically to protect themselves against power surges, officials said.
The whole process "essentially took 9 seconds," said Gent "It happened very quickly."But what triggered the shift of electricity flow and where?
As of late Friday no one was confident enough to say."Speculation is running rampant," said Gent. "I really don't want to speculate."He said it could be next week before any firm answers are known, but he ticked off a string of factors that authorities are certain played no role.
Reports of lightning hitting a facility in the Niagara Falls area have been ruled out, as have reports that a fire at a New York City electric facility may have triggered the power disaster.
The weather also has been given a reprieve because it was not hot enough either in the Ohio Valley or in the Northeast to cause such a demand on electricity that the system should have overloaded, said Gent. In fact, he said, there was plenty of extra capacity.
And terrorism has been ruled out by everyone from grid managers to President Bush.
But Gent said he wouldn't rule out that negligence by someone, somewhere might have been a cause. Investigators will have to determine whether some industry transmission standards might have been ignored, or perhaps simply conclude that the industry-crafted standards are inadequate.
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On the Net:
North American Electric Reliability Council:
http://seattletimes.nwsource.com/APWires/tech/D7SUPKB00.html
Outage probe looks to single power line in Ohio
Industry expert: Lines in that region have had trouble before
Friday, August 15, 2003 Posted: 10:44 PM EDT (0244 GMT)
(CNN) -- The power industry's watchdog council turned Friday toward a series of transmission lines known as the "Lake Erie loop" as it sought the source of the power outage that affected parts of eight states and Canada.
Michehl Gent, president of the North American Electric Reliability Council, said that though the cause remains unknown, initial evidence points to the loop that encircles the easternmost of the Great Lakes, from New York to Detroit, Michigan, and through Canada.
"We have some indications that the first transmission lines that were tripped were in the Midwest," he said on a telephone conference call with journalists. "We're not sure what that means. We're not absolutely sure that's where it happened, and we won't be sure for the next couple of days."
But, he added, "that's the center of focus."
Later Friday, Gent told CNN it appears that the first known problem was the loss of a power line in Cleveland, Ohio, at 3:06 p.m. Thursday. The loss of the power line could be an early link in a chain of events that led to the blackout, he said.
An examination of power logs as well as timelines of various sequences helped Gent's staff trace the blackout back to the loss of that 345,000 volt line
Gent said it is not known why that line went down, and his staff is still looking at what happened during the next hour.
The blackout began spreading in New England, the upper Midwest and parts of Canada just after 4:10 p.m., taking down 21 power plants in the next three minutes, according to Genscape, which monitors power transmissions in the United States.
Gent said NERC should have more answers by Monday.
The power line in Cleveland is one of 50 in the Lake Erie loop.
The loop of transmission lines has "been a problem for years, and there have been all sorts of plans to make this a more reliable thing, with cables under the lake and such, but nothing has come to fruition," Gent said.
Gent said power on the northern side of the lake was flowing from west to east just before the incident, and "as it unfolded, the power reversed itself" and nearly doubled.
"There was a big swing back and forth on the north of the lake," he said. "The whole loop had this oscillating power phenomenon that ... was essentially a nine-second event."
From that initial incident, he said, the blackout cascaded off the loop and spread before the electrical system "did what it was supposed to do" and stopped it.
NERC does not consider terrorism or cyberterrorism possible causes.
"Physical terrorism is fairly easy to rule out," he said. "There's no evidence of a blowup, or somebody breaking in."
As for cyberterrorism, "it's virtually impossible to get in without leaving some tracks," he said. "They can cover their tracks as far as who they are but they cannot cover their tracks about where they've been."
As for what the "nine-second event" might have been, Gent said, the investigation would uncover it.
"There are two possibilities," he said. "Either the rules that we have are inadequate and need to be changed to accommodate this unknown event, or somebody wasn't following the rules."
NERC's rules voluntary
NERC's rules, however, are voluntary, and the council has no enforcement abilities. Gent said he has been advocating mandatory rules for about five years, to no avail.
"There's a bill before Congress ... we had hoped that would have been passed by now," he said. "This would have allowed us to enforce the rules."
He added, "We've been increasingly concerned that economic concerns of other pressures will sort of force people to not follow the rules or to extend in some way that limits their ability to follow them."
Gent said that one of the areas investigators will look at closely is a change that took place when the power industry was deregulated.
"When the industry deregulated," he said, "it separated the owners of transmission lines and the owners of generation plants. We no longer have transmission lines built to accommodate generation systems.
"When they separated, generators started building plants at convenient locations ... without considering how transmission lines in that area would accommodate them," he said. "We have more than adequate generation for the United States and Canada but we don't have an adequate transmission system."
Gent said NERC's current efforts focus on restoration; a thorough investigation will follow.
"If we've designed a system for this not to happen, how can it happen?" he said. "Assuming we can conduct a proper investigation, then we will turn to preventing this from ever happening again."
The electrical industry created the council in 1965 after 30 million people in seven states and two Canadian provinces lost power in what became known as "The Great Blackout." It is charged with designing systems to prevent such outages.
Gent said he was personally "embarrassed" by the widespread blackout.
"My job is to see that this doesn't happen," he said. "You could say that I failed in my job. That's why I'm upset."
Transmission officials say system worked
Officials from PJM, a regional transmission organization, confirmed Friday that as the cascade started flowing through the system at 4:10:48 p.m. EDT Thursday, the system's internal controls kicked in and prevented the problem from spreading.
Within a fraction of a second, Erie, Pennsylvania, and in the northeast corner of New Jersey experienced a disruption of power that saved the rest of the grid.
The affected region's network was stable within one minute, and no other areas were hit by the blackout.
"We are really pleased that our system functions the way it was supposed to and that it isolated the problem and stopped the outages from spreading," said Ray Dottard, a spokesman for PJM in Valley Forge, Pennsylvania.
Dottard compared the cascading power outages to falling dominoes. Mechanisms built into the system stop the lines from failing, the equivalent of taking two dominoes out of a series, leaving the dominoes behind the gap standing. The missing dominoes will still cause problems, but the ones still standing will be spared.
The Erie loop, said PJM spokesman Michael Bryson, begins and ends in Buffalo, New York. It travels west to Cleveland and Detroit, then circles around the lake into Canada before crossing back into the United States.
PJM also has control of transmission lines in all of or part of Delaware, Maryland, New Jersey, Ohio, Pennsylvania, Virginia, West Virginia and the District of Columbia, according to its Web site.
http://www.cnn.com/2003/US/08/15/blackout.cause/index.html
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