WASHINGTON -The nation's worst blackout was a "largely preventable" event caused by a constellation of failures at Ohio's FirstEnergy Corp., a team of government investigators reported yesterday.
The widespread power outages Aug. 14 were triggered by the loss of three high-voltage transmission lines in Northern Ohio - which short-circuited after getting tangled with trees - and by a failure of Akron-based FirstEnergy Corp. operators to contain the problem, according to findings of a U.S.-Canadian Task Force.
Investigators said an alarm system malfunctioned in the control room of FirstEnergy preventing operators from keeping other lines from overloading or notifying neighboring utilities.
The report, released yesterday by the U.S. Department of Energy, offered the first definitive cause of the Northeast Blackout, which cascaded throughout the Northeast and parts of Canada, cutting power to about 50 million people. It painted a picture of a utility that failed to keep trees trimmed adequately and was then overwhelmed as events mushroomed out of control.
It also blamed the power transmission coordinator for FirstEnergy's region, the Midwest Independent System Operator, or MISO, which the report said was using outdated data in its monitoring and ineffective tools to analyze the system. A key tool MISO uses to evaluate the system, called a state estimator, was not working for about three hours before the blackout hit, partly because of human error, the report said.
The task force found that human error, equipment malfunctions and communication breakdowns all contributed to the system crash that left commuters stranded, people trapped in elevators and lights out in homes, factories and offices for as long as a week. More than 263 power plants went down.
"This blackout was largely preventable," said Energy Secretary Spencer Abraham, who released the report at the Energy Department during a joint press conference with Canada's minister of natural resources, Herb Dhaliwal.
Abraham said the voluntary procedures that keep the nation's power transmission grid in balance were ignored, and "a number of relatively small problems combined to become a very big one. ... Once the problem grew to a certain magnitude, nothing could have been done to prevent it from cascading out of control."
The report said that between 3:05 p.m. and 3:42 p.m., three of FirstEnergy's power lines failed, each the result of a contact between a line and a tree that had grown beyond the clearance height for the line. As each line failed, its outage increased the load on the remaining lines.
The blackout spread when grid operators failed to adjust equipment or power plant output or take certain customers temporarily off-line to restore the grid's balance. Consequently electricity quickly moved onto other lines that in turn became overloaded and shut down. At that point the blackout spiraled out of control, engulfing the Northeast and parts of Canada within minutes.
Investigators, who began probing the blackout's cause in early September, said they found no evidence of sabotage or terrorist activities and reported that all affected nuclear plants in the United States and Canada functioned property.
But they found that First- Energy and MISO violated reliability standards set by the North American Electric Reliability Council.
FirstEnergy violated at least four standards: It didn't return its system to a safe status within 30 minutes after the failure of its Chamberlin-Harding line at 3:05 p.m; it never notified nearby utilities of the problems; it failed to analyze what was happening; and it didn't adequately train its operators, the report said.
MISO, the multistate grid operator operating from Indiana, did not notify other regions about the potential problems and didn't ensure that it had adequate tools to analyze system problems or adequate grid monitoring capability, according to the report.
The industry is largely self-regulatory on reliability issues with no penalty for rule violations.
FirstEnergy officials disputed the report's conclusions yesterday, saying investigators should have considered the role of a transmission system that was built to transmit power locally, not over long distances as it has in a deregulated market.
"We still do not believe the outage can be explained simply by events on our system," said Kristen Baird, a FirstEnergy spokeswoman. "By focusing on our events, we don't feel the task force addressed the complexity and magnitude of operations on the grid. The transmission system is being used today in a way for which it was not designed."
Investigators found that MISO violated standards by failing to notify other reliability coordinators at utilities of potential problems and because its monitoring system was disabled.
That occurred when MISO's "state estimator," used to evaluate the reliability of the power system, was turned off by a MISO analyst who was troubleshooting an unrelated problem.
"After fixing the problem, he forgot to re-enable it, so ... the tools were not returned to normal automatic operation," the report said. "Thinking the system had been successfully restored, the analyst went to lunch."
At 2:40 p.m., MISO discovered that its state estimator was not running on an automatic, five-minute schedule.
The energy secretary pointed to the report's findings as further evidence that the nation needs mandatory rules on the use of its interconnected transmission grid. Such rules have been included in the comprehensive energy bill passed Tuesday by the House and now before the Senate.
The bill would set up regional transmission organizations that would develop and enforce mandatory standards and rules with oversight from the Federal Energy Regulatory Commission.