International Transmission Says "Loop Flow" Caused Grid Collapse

Nov 04, 2003

Novi, Mich., November 5, 2003 - International Transmission Company endorses today's report from the Michigan Public Service Commission on its investigation into the blackout of August 14 and particularly its explanation of the role of the initial power surges (i.e., loop flow) through Michigan to Ohio.

"I commend the Michigan Public Service Commission for a thorough and timely review and analysis," said Joseph Welch, President and CEO, International Transmission Company. "There is almost no question about the timing and sequence of events that resulted in the blackout," said Welch. "Problems in northern Ohio led to line outages that caused the massive 2,000 megawatt surge of power and the accompanying voltage drop that led to the collapse of the system."

Electric power flows according to the path of least resistance. However, electric transactions are scheduled from one specific location to another without regard to the actual flow of energy. Loop flow results from the effect of those unscheduled flows. In this case, when the lines in Ohio disconnected, the electricity found a path across the state of Michigan and back into Ohio.

International Transmission's Michigan Electric Power Coordination Center in Ann Arbor precisely tracked the amount of power flowing into and out of Michigan. Using its Disturbance Storage and Logger (DSL), an automated computerized system, International Transmission was able to collect comprehensive data in two-second increments on power flows, loads, generating plant output, line outages and other critical factors.

"Our DSL showed that the timing and sequence of events that day and clearly demonstrated that the power increase entering Michigan was in response to demand from Ohio." Welch said.

"One of the underlying deficiencies was an almost utter lack of communications between transmission jurisdictions. With even a short notice of problems, there were steps we could have taken. In addition to investing in upgrading the transmission infrastructure, we need mandatory, enforceable reliability standards." Welch said.

International Transmission Co.
Anne Jinks

Franco Public Relations Group
Fred Zosel