Jimmy Glotfelty, a top official with the U.S. Department of Energy (DOE), last week expressed confidence that a joint U.S.-Canadian task force investigation into the historic Aug. 14 blackout that cut across portions of both countries will be able to pinpoint the cause or causes of the massive series of power outages.

“We feel very confident,” said Glotfelty, director of the DOE’s Office of Electric Transmission and Distribution. “We have a tremendous of data,” he said. “The data, as you dig deeper and deeper and deeper, tells you more and more, and we are very confident that we will get to be able to tell the public how this happened and why this happened,” said Glotfelty, who is also serving as a U.S. coordinator for the task force.

The task force on Friday outlined its initial findings related to the sequence of events leading up to the blackout. The initial chronology was unveiled by the task force’s co-chairs, U.S. Secretary of Energy Spencer Abraham and Herb Dhaliwal, Canada’s minister of natural resources.

At a later point, a reporter noted that certain events on the day of the blackout were not included in the timeline released by the task force. Specifically, the reporter cited publicly released transcripts detailing phone conversations between operators at Cinergy and the Midwest Independent Transmission System Operator on the day of the blackout.

Glotfelty said that it would be wrong to assume that just because the transcripts weren’t cited in the chronology, the task force had decided that these conversations weren’t relevant to the overall blackout.

“There are other factors that have happened before 12:05 and ones that are not on here that may have relevance,” the DOE official said. “As we dig deeper, we will draw conclusions as to what their relevance is.”

In detailing the events leading to the blackout, the report’s sequence starts with a series of generators tripping offline from 12:05 p.m. through 1:31 p.m. that day, beginning with an American Electric Power (AEP) unit in Ohio.

The report noted that there was an apparent “voltage collapse” that day, which occurred on portions of the transmission system surrounding and within the northern Ohio and eastern Michigan load centers.

The report devotes a fair amount of space explaining the role of reactive power in the overall grid. Transmission system voltage is needed to transfer electric power from generating stations to load centers. Reactive power is the component of total power that assists in maintaining proper voltages across the power system.

“Reactive power is greatest near load centers where it’s necessary,” Glotfelty noted in a conference call. Reactive power “is a component that keeps the frequency and voltage of the transmission system at the appropriate level. When you have reactive power disturbances, as well as frequency disturbances, the system normally corrects itself,” the DOE official noted. “In this instance, it seems like that did not happen.”

Meanwhile, the report said that most of the events that appear to have contributed to the blackout occurred during the period from about noon EDT until 4:13 p.m. EDT (all times in the chronology are in Eastern Daylight Time).

“Generation and transmission operating events plus scheduled interchange through the systems in the region may have affected events later in the day,” the report said. “The investigators are studying these events beginning at 8 a.m. on Aug. 14 to determine whether they were significant to the blackout.”

The first generator to go offline was AEP’s 375 MW Conesville Unit 5 plant in central Ohio at 12:05, followed by DTE’s 785 MW Greenwood Unit 1 at 1:14. That unit is located north of the Detroit area. Greenwood Unit 1 returned to service at 1:57.

At 1:31, FirstEnergy’s Eastlake Unit 5 in northern Ohio (597 MW) tripped. The unit is located in northern Ohio along the southern shore of Lake Erie and is connected to the 345 kV transmission system.

Much of this sequence of events dovetails with a chronology previously issued by Ohio-based FirstEnergy earlier this month.

“These generating unit trips (shutdowns) caused the electric power flow pattern to change over the transmission system,” the report said. The timeline goes on to offer details on several transmission lines disconnecting in the Buckeye state, generation trips in central Michigan and subsequent events tied to the cascading outages.

“While this timeline marks an important milestone in this bi-national investigation, it’s important to note that this timeline is not intended to indicate — and should not be assumed to explain — why the blackout happened,” said Abraham. “The timeline is intended to provide an early picture of what happened.”

Abraham noted that the power grid “is a complex machine that likely failed in complex ways, and a thorough, professional investigation is under way to competently explain the causes of the blackout.”

Abraham said that the overall timeline is “an important step in our search for answers. But it’s only a step. It is far from a final product, and much work needs to be done before we can draw any definitive conclusions.”

The entire 14-page report can be downloaded at: www.doe.gov.

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