Trigger for swings in power still unknown
Advertiser News Services
A day after the mysterious record blackout that descended on New York, Canada and the Midwest, about the only thing electricity experts could say for sure was: It could happen again.
Associated Press
But what happened?
Stranded commuters slept on the steps of the post office at 33rd Street and Eighth Avenue in New York early yesterday.
It will take days or weeks before engineers determine the cause, or series of causes, said Michehl R. Gent, president of the North American Electric Reliability Council.
An early sign of trouble Thursday was a wild swing in power in the loop surrounding Lake Erie, he said in a conference call from the Princeton, N.J., headquarters of the nonprofit industry group that oversees the power system.
Shortly after 4 p.m. EDT Thursday, instruments recorded 300 megawatts of power moving eastward toward New York. Then, in a sudden reversal, 500 megawatts surged westward, Gent said. Wild fluctuations continued for 9 seconds at various points in the Northeast.
Gent could not say where the initial trigger occurred, beyond "the Midwest." He ruled out lightning as a possible trigger, suspected by some officials earlier, and reiterated that there were no signs of an attack.
He blamed himself. "My job is to see that this doesn't happen, and you can say that I failed in my job," Gent said. "That's why I'm upset."
The nine-second jolt, after a series of power-line failures in the Cleveland area, rolled across the East, blacking out cities as far away as Toronto and New York and affecting 50 million people.
"It just dropped on us like a ton of bricks," said Anthony Earley, chief executive of Detroit utility owner DTE Energy Co. About 600,000 of its 2.4 million customers still lack power, and it will take all weekend to restore the system, Earley said.
Five high-voltage power lines in the Cleveland area were tripped off line between 3:06 p.m. and 4:06 p.m. EDT, the council said. Large power swings were seen in Canada and the eastern United States at 4:08 p.m., though no significant failures were reported in those regions before 4:11 p.m. "It is not clear if these events caused the event or were a consequence of other events," the council said.
The investigators have discarded speculation that the culprit was a failure of the Niagara Mohawk system in New York, or collapse of the transmission system in Canada.
Gent said the nine-second power reversal may have triggered shutdowns at power plants and transmission lines.
Officials at Midwest Independent Transmission System Operator, which runs the grid covering Indiana, Michigan and parts of Ohio, confirmed in a separate call that they had observed power-line failures more than an hour before the cascading blackouts began.
"At that time, our analysis did not indicate we were in this type of cascading event," said Roger Harszy, the Carmel, Ind.-based group's director of operations, who was in the control room when the first failures occurred. "When we saw the power swing reverse around Lake Erie, we realized it was a serious event."
An emergency conference call was held with managers of other regional power grids. The cascading failures occurred too fast to prevent, Harszy said.
Bruce Wollenberg, director of the University of Minnesota Center for Electric Energy, likened the breakdown to closing a road at rush hour. "The power flows onto other parts of the grid," Wollenberg said, "and if they are already heavily loaded, then you get a gridlock in the electric power system."
As power continues to flow, lines get overheated and measuring equipment shuts them down, Wollenberg said. "You do that enough times, and it's going to plunge some systems into darkness." That's what happened in the 1965 blackout, when one circuit went out in Canada, he said.
The reversal tripped off a series of transmission lines, protecting the system from damage, said Linda Blair, a spokeswoman at International Transmission Co.
Rapid swings like Thursday's wreak havoc, said David Whiteley, former chairman of the reliability council's planning committee. "The power grid does not respond well to very rapid, sudden perturbations," he said.
Gent said the Northeast was using 75 percent of available power when the blackout occurred. Industry experts speculated, however, that transmission lines might have been running at capacity.
The council requires that power generators maintain adequate reserves, but there is no such provision for lines that carry the electricity to homes and businesses.
Bloomberg News Service and the Philadelphia Inquirer contributed to this report.
