IEEE Power & Energy Magazine - January/February 2014 - 30

delayed the start of the inspections.
Approximately 1,500 mi of transmission were inspected between 17
and 21 August.
several instances of damage
to generators were reported. Five
units had failed rupture discs,
which kept these units unavailable
for more than 24 hours. rupture
discs are a pressure relief location
for the steam condenser. they are
MICHIGAN
Hampton
prone to failure when the entire
electrical network goes down, as
a consequent loss of circulatingThetford Greenwood
water pumps and vacuum pumps
results in a buildup of pressure in
Blackfoot
the condenser. the rupture discs,
Belle River
Jewel
however, are designed to fail under
St. Clair
Pontiac
stressed conditions and probably
Madrid DETROIT
prevented serious physical damStephens
age to the units. the availability of
Wayne
Majestic
spare discs so that units could be
Waterman
returned to service was an issue;
Brownstown
the need for so many simultaneFermi
Monroe
ous rupture disc replacements had
not been experienced previously.
One unit suffered a loss of configure 4. Eastern Michigan power system restoration (orange lines indicate 500 kV,
trol air on the generator seal oil
red lines indicate 345 kV, and blue lines indicate 230 kV).
system valves, resulting in oil in
the
generator.
the
output
of
another unit was limited due to a
connection to the Airport substation was energized, enabling
restoration of critical load. But access to river rouge and other ground in the no load/low load trip switch. Another unit had
southern generating plants was hampered by a fire at an oil an overheated boiler circulating-waterpump, which needed to
refinery at the time of the blackout that forced an evacuation of be replaced. Finally, one unit (river rouge 3) suffered bearing
the area. extension of energization to the Waterman station near damage during the event, which left the unit out of service for
downtown Detroit was therefore delayed until 8:00 a.m. With weeks. Lessons learned from the restoration experience in and
the closure of the Blackfoot-madrid 345-kV line at 8:55 a.m. around Detroit include:
and the closure of the ring bus at Pontiac at 9:30 a.m., the 345✔ the restoration effort was vulnerable to Detroit edikV loop around the Detroit metro area was finally reestablished.
son's computerized "in-service application" function,
A second 345-kV tie to consumers energy, the thetford-Jewel
used to prioritize and dispatch repair crews. this
circuit, was reclosed at 1:38 p.m. on 15 August.
function was not operable due to the loss of power,
As restoration continued, Detroit edison followed a
forcing repair crews to make a number of extra trips
practice of energizing whole distribution centers without
back to service centers to pick up new work orders.
isolating individual circuits. up to this point, most of the
✔ Practices in maintaining spare rupture discs for genrestoration actions were preparatory to restoring load. Diserators were deficient for coping with system wide
tribution crews were needed as transmission was restored in
disturbances and hence were changed.
order to balance load against available generation. substantial restoration of distribution started at about 2:30 p.m. on Southern Michigan
15 August. the restoration of the essex 24-kV station at 5:30 the southeastern corner of the consumers energy system in
p.m. picked up a significant portion of the load in the city of southern michigan had also blacked out. After the initial disDetroit. the last of four critical pumps for the city's water turbance, operators received conflicting information about the
and sanitation department was restored in the evening.
amount of generation. Operators believed the consumers energy
Detroit edison conducted inspections of transmission lines system was undergenerating, but the high frequency (60.2 hz)
and switchyards over the next several days to maintain system suggested the opposite. Operators maintained generation levels
reliability. the inspections were conducted both by air and on until the status of the system could be ascertained. restoration
the ground, and they were both visual and thermal. storms efforts commenced with an emergency page of transmission
30

ieee power & energy magazine

january/february 2014

Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - January/February 2014