Preliminary findings of an ongoing investigation into the cause of widespread power outages that swept across Florida last Tuesday indicate that the primary cause was human error, Florida Power & Light Co. (FPL) said Friday.
According to FPL, a field engineer who was diagnosing a switch that had malfunctioned at the company’s Flagami substation in west Miami disabled two levels of relay protection without authorization and contrary to FPL’s standard procedures and established practices. During the diagnostic process a fault occurred and, because both levels of relay protection had been removed, it caused an outage ultimately affecting 26 transmission lines and 38 substations, the company said.
One of the substations affected serves a pair of 693 MW nuclear units and a natural gas unit at FPL’s Turkey Point power station, 25 miles south of Miami. Those units automatically shut down just after 1 p.m. due to an under-voltage condition.
Two other FPL generation plants were also affected, bringing a total of 3,400 MW of generating capacity off the grid in a matter of minutes and knocking out power to an estimated one million customer accounts, including 584,000 FPL customer accounts, representing about 2.5 million people statewide. FPL has said it began restoring power to customers in about one hour and virtually all affected customers had power by 4:30 p.m.
On Friday FPL President Armando Olivera issued an apology to the company’s customers.
“We understand that this event caused a significant inconvenience. We also understand that reliability and safety are cornerstones of our commitment and accountability,” Olivera said. “While in this instance we failed to perform to our expected standards in regard to reliability, safety was never an issue and the safeguards built into our system worked as intended. Because of this and the experience, training and practice drills of our work force, we were able to restore power to our customers quickly.
“These preliminary findings address the most pressing questions that have been posed. We are committed to completing a full and thorough investigation, to cooperating fully with the appropriate regulatory agencies and to sharing our findings publicly when the investigation is completed. We will address any issues that are identified in order to prevent a recurrence.
“While the investigation is ongoing, to this point we have no indication that there are any deficiencies with the design of our facilities or with our maintenance procedures. However, out of an abundance of caution, we have implemented interim changes governing relay protections to prevent a recurrence,” Olivera said.
An “event analysis team” led by the Florida Reliability Coordinating Council (FRCC) was established midweek to determine “the root cause of the equipment failure” that resulted in the power outages. The FRCC team, including one member from the North American Electric Reliability Corp. (NERC), an observer from the Federal Energy Regulatory Commission, an observer from the Florida Public Service Commission and several industry experts from Seminole Electric, Progress Energy Florida, Tampa Electric Co. and FPL, is due to hold its first meeting, which will be closed to the public, on Monday (March 3) in Tampa. The investigation is expected to take several months. The results of the team’s analysis will then be turned over to FRCC’s compliance staff to determine whether any NERC reliability standards were violated, according to FRCC President Sarah Rogers.
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