The Michigan Public Service Commission (MPSC) issued an order requiring electric companies in Michigan to review and, if necessary, make operating changes to avoid future power disruptions such as those that occurred during the Aug. 14, 2003, blackout.

The MPSC order follows the release of the final report by the U.S.-Canada Power System Outage Task Force on the blackout.

The report found that the sensitivity of various relay settings on the transmission system contributed to the spread of the cascading blackout. However, the report also notes that the relays were not intended to protect systems other than their own. The appropriate relay setting is a new concern that had not been previously identified in the U.S.-Canada interim report released on Nov. 18, 2003.

“We previously concluded that Michigan's electrical companies did not cause the August 14 blackout, and the bi-national report released today verifies that,” notes MPSC Chair J. Peter Lark. “But today's final report identifies a new concern with the operation of electric transmission relays in Michigan and Ohio. The Michigan Public Service Commission intends to make sure that these relays do not play a part in any potential future blackouts. That is why we are directing Michigan electric companies to analyze their relay settings and make any necessary corrections.”

The order directs all electric utilities and transmission companies operating in Michigan to analyze and, if necessary, make operating changes to their impedance relay settings to minimize the likelihood of future cascading outages. The utilities and transmission companies are directed to submit reports on their findings and actions by May 10. These reports should also include responses to the findings of the bi-national report, especially related to impedance relay settings.

“My colleagues and I will continue to review the bi-national report and may seek additional information and issue further orders,” Lark adds. “We want to make sure that Michigan's utility and transmission companies have taken all steps possible to reduce the likelihood of future power disruptions and to enhance electric reliability in Michigan.”

The MPSC is an agency within the Department of Labor & Economic Growth.