The analysis of the February 26, 2008, category four system disturbance in Florida has led to the release of three industry-wide reliability advisories, announced the North American Electric Reliability Corporation (NERC) on June 26. The advisories follow the recent release of an interim report on the outage by the Florida Reliability Coordinating Council (FRCC), which contains a number of recommendations to users, owners, and operators of the bulk power system in Florida aimed at preventing recurrence and improving system response to all disturbances.

The first of the three advisories deals directly with the root cause of the outage, a decision to disable key protective relays in a substation west of Miami while troubleshooting was underway. The advisory encourages the industry to review practices and procedures to ensure that proper authorizations are obtained before such measures are taken.

The remaining advisories focus on the capabilities of generation plants to “ride-through” changes in voltage or frequency on the system without unexpectedly disconnecting from the grid, while still protecting generating equipment from permanent damage. They also include provisions to help grid operators and planners better understand and account for generators that may disconnect from the grid during a severe disturbance.

“Every system disturbance is an opportunity to learn more about how the system responds to extreme conditions,” commented Robert Cummings, NERC’s director of events analysis and information exchange. “This event has brought to light a few key issues about the behavior of the system that the entire industry can use to improve the bulk power system’s response to future disturbances.”

Although most of the affected customers were restored within one hour of the initiating events, the Florida outage was ranked a four on NERC’s system event classification scale for the loss of roughly 4,500 MW of customer load, 4,300 MW of generation, and 26 transmission lines. NERC’s event classification scale has five levels and is designed to designate the severity of bulk power system disturbances; category five is the most severe on this scale. Three other events have been ranked a four or higher in the past year out of 33 tracked bulk power system disturbances.

“Our focus is on ensuring the reliability of the bulk power system in North America and putting the standards in place that will eventually reduce the likelihood and severity of future system disturbances,” commented Rick Sergel, President & CEO of NERC. “Unfortunately, no standards or enforcement process can prevent all system disturbances from occurring. Issues like severe weather, simultaneous multiple equipment failure and human error can occur, but it’s our job to minimize their effects. Today’s (June 26) advisories will help to do just that.”