A Flicker Away From a Blackout
Tuesday, June 21, 2005
TORONTO -- At 4:15 p.m. on May 27, the lights flickered across Ontario.
Subway cars in Toronto rolled to a stop while safety signals were reset. Pizza oven doors flew open on the ground floor of the city's landmark CN Tower. Cement and steel plants paused while machinery was restarted. Tens of thousands of computers automatically shut down and rebooted.
Hydro One, the Toronto-based electric utility, quickly issued a press statement seeking to reassure the public that the utility's "equipment protection worked as designed to isolate the fault."
In fact, the situation was much more tenuous. The power blip involved an extremely rare, still unexplained failure of two protection systems, according to internal documents of the utility, reports to oversight agencies and eight engineers. The eight are part of a group that has been on strike since June 6. By their accounts, the failure brought the region's power grid to the verge of a blackout like the one that struck on Aug. 14, 2003, plunging 50 million people in the United States and Canada into darkness.
"It was very bizarre, very disconcerting. And we may have a major problem on our hands," said engineer Aaron Cooperberg.
He and other engineers said that because they are striking, the precise cause of the malfunction has not been identified, and they say it could happen again. "Fundamentally, we had a very close call, and we don't know why," said another engineer, one of three who asked not to be identified, saying they feared retaliation by the company.
The electrical grid handled by Hydro One, which has 17,000 miles of high-power electric transmission lines throughout Ontario, managed the blip "very well," said Peter Gregg, vice president for corporate communications at the utility. Much of its cause is still not understood and under investigation, he said, and "we continue to be disappointed with the striking staff who seem to want to scaremonger on this incident."
Striking engineers said they were not seeking to pressure the company as part of their labor dispute. They said they were speaking out because they were worried that a threat remains to a power system they care about. "We're not pointing fingers," said one. "This isn't about a strike. It's about reliability of the system."
The May 27 incident set power generators in New York, Massachusetts, New Brunswick and Ontario swinging in wild oscillation, fighting one another to try to cope, according to official reports filed with oversight authorities in Canada and the United States.
The competition among generators produced what experts call a "ring" on the grid. According to an internal company document submitted to regulators, "the ringing lasted about 12 seconds." Computer simulations showed that "the oscillations can grow with time and result in the breakup of the power system in about 30 seconds," the internal document noted.
The industry oversight agencies have not yet publicly drawn any conclusions from the event. Edward Schwerdt, head of the Northeast Power Coordinating Council, which reviews the system's grids in New York, New England and eastern Canada, said the May 27 event was an "extreme contingency" but that no additional precautions to prevent a recurrence are being taken until an inquiry is complete.
An official of the U.S.-Canada oversight agency, called the North American Electric Reliability Council, also said they are awaiting a report. "We could see a change in the system frequency on the continent. We knew that something big had happened," said Glenn Brown, who heads a disturbance analysis group for the council. He compared the irregularity to one that blacked out all of Jacksonville, Fla., in April 2002.