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By Times WiresA series of failures apparently started in the Midwest. Now officials want to know why and how to prevent it.
In a transmission system control room Thursday in Carmel, Ind., Roger Harzy stared at a computer screen that had just revealed 1,000 megawatts of wayward electricity surging around the top of Lake Erie from the Toronto area into Detroit.
Moments before, Michigan power companies had been routinely shipping several hundred megawatts to Toronto, but the flow - enough to light more than 500,000 homes - unaccountably reversed in a power tsunami that the system was not prepared to handle.
The burst of power flowing through the area was so large that generating plants and circuits on high-voltage transmission lines shut down to protect vital equipment from damage. The shutdowns apparently began in Michigan and Ohio, effectively cutting off entire sections of states from the rampaging electricity flows. In seconds, huge mismatches in demand and supplies of power were created and the disruptions jumped to the Canadian-U.S. border, then into New York State.
Harzy, operations director for a transmission coordinating organization serving energy companies in 15 states around the Great Lakes, had time to grab a hotline to call his counterparts in Canada and states to the east. In moments, as he was talking to Toronto, its transmission network was already shutting down. "It happened very quickly. It was the beginning of the cascade," Harzy said Friday.
Ultimately, dozens of lines and about 100 power plants, with a staggering 61,800 megawatts of generation, had shut down - apparently before any human could react. The series of failures began about 4:08 p.m., and was over within roughly five minutes.
"This whole event was essentially a 9-second event, maybe 10," said Michehl Gent, president and chief executive of the North American Electric Reliability Council, describing how the problem started. His organization was founded after the 1965 blackout to prevent repetitions of it.
Gent and other officials could offer no explanation for the failure of a series of systems that is supposed to isolate such problems, keeping a blackout in one region from dragging its neighbors into darkness, as happened Thursday. Some of those systems worked, notably in northern New Jersey and Pennsylvania, preventing the failure from spreading southward, and in Connecticut, protecting New England. Others did not.
On Friday, the White House announced a U.S.-Canadian task force will investigate the cause of the blackout and identify ways to prevent it from happening again. It will be headed by Energy Secretary Spencer Abraham and Canadian Natural Resources Minister Herb Dhaliwal.
As for the first event that set the disaster in motion, no one is sure yet what it was.
But records show that, in the two hours before the full collapse, there was a series of problems on transmission lines in Ohio. Records kept by SoftSwitching Technologies, a company hired by the power industry to monitor the grid, show episodes of voltage sagging too low on those lines - at 2:24 p.m., twice at 3:17 p.m. and most seriously, twice again at 3:43 p.m. The more serious problems might have involved a transmission line in Cleveland that investigators were focusing on.
Officials were able, though, to rule out a number of theories spun Thursday, including high demand due to heat, lightning strikes in the Niagara Falls area, or a fire at a power plant.
And after New York state officials said they believed it was a problem at the Perry nuclear reactor near Cleveland, the operators of that plant disputed that.
Either way, officials at both the New York Independent System Operator, the consortium that manages the state's grid, and the North American Electric Reliability Council, said it appeared that the problem began in the Midwest, crossed into Ontario near Detroit, and then passed into New York at Niagara Falls and perhaps other points, as well.
In summertime, power produced in the Midwest is often sold to consumers in the Northeast, but the current does not always take the most direct route; instead, it often takes a loop around Lake Erie and through the Canadian province of Ontario.
Gent said 300 to 500 megawatts - enough to electrify a small city - were moving west to east, from Michigan to New York through Ontario, when the problem struck. It was either the failure of some power plants or of some transmission lines. Suddenly, he said, the flow of electrons reversed, pulling 500 megawatts from east to west, out of New York - a swing, in the space of a few seconds, of as much as 1,000 megawatts, the output of a large power plant.
The problem is that the power grid is like a game of tug of war, which works as long as neither side - the generating stations and the load centers - wins. If one side falters, and the rope moves too far, everyone on the other side will fall down.
In a system with hundreds of critical components, the top priority of each is not to keep the lights on, but to protect itself from overload. Power lines are guarded by automatic devices that "isolate" them, or take them out of service, when the tug-of-war rope moves too far.
Some experts were not surprised at the system's problems.
Scientists and engineers with the National Research Council warned the White House and Congress about the vulnerability of the power grid as recently as November, saying nationwide weaknesses needed to be repaired.
The report, "Making the Nation Safer: The Role of Science and Technology in Countering Terrorism," was issued in response to the Sept. 11 attacks, but it noted that the systems were "subject to increased stress even without the threat of terrorism."
"It's something that's been coming I think for the past 35 years," said Mel Olken, editor in chief of IEEE Power & Energy Magazine, which is published by the Institute of Electrical and Electronics Engineers.
"We just kept stretching our systems further and further" as homes and businesses were upgraded to cope with air conditioners and computers.
New York Assemblyman Paul Tonko, an engineer and chairman of his chamber's Energy Committee, said there hasn't been major spending to improve transmission lines by the state since the 1970s and no major work by utilities since the 1960s.
But the blackout will give new urgency to an energy plan that has languished in Congress for more than two years, lawmakers said, and they asserted that elements aimed at upgrading the power infrastructure will gain importance.
- Information from the Washington Post, New York Times and Associated Press was used in this report.