Automated controls prevent spread of blackouts
COLUMBUS, Ohio, Aug. 22, 2003 — American Electric Power (AEP) has released a timeline of events and conditions detected by automated controls on its transmission grid Aug. 14 when massive amounts of power were drawn north from AEP’s grid to loads in the vicinity of Lake Erie immediately prior to the blackout that affected all or parts of eight states and eastern Canada.
“This timeline provides details of the rapid escalation of events that impacted our transmission grid, but we will not get involved in the speculation as to the cause of the abnormal power flow swings across the grid or theorize about events occurring outside our system,” said Tom Shockley, AEP’s chief operating officer. “We have provided our data to the North American Electric Reliability Council (NERC) to be included in its analysis of the blackout. Today we are discussing the data at a Department of Energy technical hearing and in a conference call with our state regulators. We also are assisting the investigators as they determine the cause of the outage.
“It’s important to note that the load and generation on AEP’s grid were in balance both before and after the beginning of the blackout. This explains how we were able to maintain grid stability after our automated controls correctly reacted to prevent the blackout conditions from cascading through our seven- state eastern grid and to protect lines and equipment from potentially extensive damage,” Shockley said. “Our transmission system is a $3 billion asset that includes the world’s largest network of high-capacity 765-kilovolt (kV) lines that serve as the backbone of the East Coast’s grid. It’s a robust, well-designed system that proved its worth last week.”
AEP avoided potential widespread outages when automated control systems on its transmission equipment detected abnormal operating conditions and “tripped” — or opened — lines that interconnect with FirstEnergy’s transmission grid to the north. Lines that tripped are near Canton in northeastern Ohio and Findlay in northwestern Ohio.
After a line opens or trips, it may close again and allow power to flow. Or, if the breaker operates (opens and closes) several times and the abnormal condition is still sensed by the protection devices, the breaker will lockout, preventing power flow on the line until it is reset by an operator.
“The data indicates that our automated systems performed as designed,” said Henry Fayne, AEP’s executive vice president — energy delivery. “By quickly detecting abnormal conditions on the lines and attempting to correct the conditions, the automated relay protection systems prevented the blackout from spreading onto AEP’s extensive transmission network and shielded our equipment from possible substantial damage.”
When tripped by the automated control systems, a number of the lines were carrying power flows well above the summer emergency rating for the lines because of the massive amounts of power being drawn north from AEP’s system. For instance, the Canton Central — Cloverdale 138 kV line, with a summer emergency rating of 197 megavolt-amperes (MVA), was carrying 332 MVA when it tripped. The East Lima-Fostoria 345 kV line, with a summer emergency rating of 1,383 MVA, was carrying 2,000 MVA when the automated controls tripped the breaker. If a facility operates at or above the summer emergency rating the equipment can suffer thermal damage.
“It is likely that the automated controls tripped some transmission lines moments before they would have burned down because of extremely high power flows out of our system,” Fayne said. “However, the load and generation on AEP’s grid were in balance at this time, which helped prevent widespread blackouts in AEP’s service territories. The size and robust capacity of our grid can handle large swings and remain stable. During this time, our transmission operators were in contact with FirstEnergy and PJM, our reliability coordinator, analyzing the situation as events developed.”
AEP had approximately 14,000 of its 5 million customers without power for several hours on Aug. 14. This localized outage, in an area near Mt. Vernon in east-central Ohio, occurred at 4:38 p.m. EDT, approximately 27 minutes after the large blackout began. Indications are that the localized outage is related to other transmission outages in Northern Ohio. Power to the customers was restored by 9:15 p.m.
TIMELINE OF EVENTS
Summary of Major AEP Transmission Events
8/14/2003 Blackout – All Times EDT
3:41:33 p.m. South Canton — Star, 345kV Circuit, Line Lockout — high loading (1,272 MVA with a summer emergency rating of 1,383 MVA) and phase to ground trip. AEP owns 0.69 miles; FirstEnergy owns 33.42 miles. Star is a FirstEnergy substation.
3:42:53 p.m. Cloverdale — Torrey 138kV Circuit, Line Lockout — high loading (354 MVA with a summer emergency rating of 245 MVA). AEP owns 0.28 miles; FirstEnergy owns 6.86 miles. Cloverdale is a FirstEnergy substation.
3:44:12 p.m. East Lima — New Liberty 138kV Circuit, Line Lockout — high loading (152 MVA with a summer emergency rating of 188 MVA) and phase to ground trip. AEP owns the entire line.
3:45:33 p.m. Canton Central — Cloverdale 138 kV Circuit, Line Lockout — high loading (332 MVA with a summer emergency rating of 197 MVA). Breaker failure operation due to multiple operations of 138kV breaker “A1”. (Breaker had six trip- and-close operations in less than three minutes). This forces the Canton Central — Tidd 345kV line to temporarily operate to isolate the faulted 138 kV Breaker “A1”. The Canton Central — Tidd 345kV line was abnormal for 58 seconds before resuming normal operation. AEP owns 0.38 miles of Canton Central — Cloverdale; FirstEnergy owns 12.20 miles. Cloverdale is a FirstEnergy substation.
3:51:41 p.m. East Lima — North Findlay 138kV Circuit, Line Lockout — high loading (200 MVA with a summer emergency rating of 247 MVA) and phase to ground trip. AEP owns the entire line.
4:05:55 p.m. Dale — West Canton 138kV Circuit, Line Operation — high loading (estimated load – 329 MVA with a summer emergency rating of 245 MVA). Line remains open at Dale end. AEP owns 3.57 miles; FirstEnergy owns 12.35 miles. Dale is a FirstEnergy substation.
4:08:58 p.m. Galion — Muskingum River — Ohio Central 345 kV Circuit, Line Lockout — high loading (1,320 MVA with a summer emergency rating of 1,281 MVA). AEP owns the entire line. Galion is a FirstEnergy substation.
4:09:06 p.m. East Lima — Fostoria Central 345kV Circuit, Line trip at 2,000 MVA (summer emergency rating of 1,383 MVA) — high loading. Auto reclose is delayed by the Synchronizing Check Relay (a snapshot of data at 4:09:22 p.m. from East Lima’s protective relay showed FirstEnergy and AEP to be 104 degrees out of synchronization). Line closed successfully in 1 minute and 44 seconds. AEP owns the entire line.
4:09:22 p.m. Cloverdale — East Wooster 138kV Circuit, Line Lockout — high loading (data not available). AEP owns 0.61 miles; FirstEnergy owns 20.39 miles. Cloverdale is a FirstEnergy substation.
4:10:41 p.m. Fostoria Central — Galion 345kV Circuit, Line Lockout — high loading (data not available). AEP owns the entire line. Galion is a FirstEnergy substation.
4:38:02 p.m. Academia — Howard 138kV Circuit — Breaker failure operation due to multiple operations of 138 kV Breaker “S” (breaker had six trip and close operations in a short time period — high loading and phase to ground trip). This caused a total outage to Academia Station interrupting approximately 14,000 AEP customers. AEP owns the entire line.
American Electric Power owns and operates more than 42,000 megawatts of generating capacity in the United States and select international markets and is the largest electricity generator in the U.S. AEP is also one of the largest electric utilities in the United States, with almost 5 million customers linked to AEP’s 11-state electricity transmission and distribution grid. The company is based in Columbus, Ohio.