A top official with PJM Interconnection last week said that the grid operator experienced “extreme, large flows” west-to-east on its system on the afternoon of Aug. 14 when a massive and historic blackout hit parts of the Northeast, Midwest and eastern Canada.

At around 4:10 p.m. on the first day of the dramatic series of outages, PJM saw 2,000 MW of power flow “increase across our system from the west into the east and up into New York,” said Michael Kormos, vice-president for operations at PJM. Shortly thereafter, that flow changed direction and came back into PJM. The flow back into PJM was a “little less” than 2,000 MW, he said.

A PJM 500-kV line “loaded up very quickly,” Kormos noted, with voltages on the 500-kV line then depressing “very quickly.” The PJM official said that one event was the “direct result” of the other. “As the flows increased rapidly through our system, the voltages were depressed,” Kormos noted. But PJM’s system was “able to basically respond and rebound,” he said, with the system able to “come back up very quickly to the point where the actual flows reversed.”

Kormos made his comments in a conference call with reporters, in which he gave a detailed overview of a presentation the grid operator gave on Thursday to its members committee related to the events of Aug. 14.

The report also includes a timeline related to when various PJM power lines tripped offline on that day. For the most part, this timeline reflects an initial west-to-east flow of power, Kormos noted, with the one exception possibly being the Branchburg-Ramapo line, which is PJM’s main tie to New York.

He said that this line “tripped out fairly early in the process, but other than that, the system seemed to go west-to-east, where the tie-lines in the western part of our system tripped out, followed by the eastern ties, but we’re talking in most cases seconds, if not minutes, that this was all happening.”

PJM also “lost a large number of generation” units on its system, Kormos told reporters. Most of the affected generators were taken offline “due to the fact that the transmission around them had been disconnected.” He added that some units “did trip out where the generation stayed intact,” mentioning New Jersey’s Oyster Creek nuclear power plant specifically.

Kormos said that the first plant in the PJM region knocked offline during the day of the blackout was the Armstrong power plant in Allegheny Energy’s service territory in Pennsylvania. This plant went offline at ten minutes after 4:00 p.m.

The data included in the report is preliminary and subject to change. “This is still raw data for us,” Kormos said in reference to the report.

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