IEEE Power & Energy Magazine - January/February 2014 - 32

Operators must prioritize critical loads during restoration,
including water and sanitation system pumps, off-site power
for nuclear generating stations, and airports.
of potentially damaging equipment. reactive devices alone
✔ the next step is to reassemble a skeletal high-voltage
are insufficient to regulate voltage on an unloaded transmisnetwork.
sion system. the system is vulnerable throughout the process:
✔ then a "cranking" path for generation must be proat least one instance was observed of a fully restored area colvided so as to assure the system is stable and will be
lapsing, forcing utility personnel to start all over again.
restored without sustaining excessive voltages.
the ability to tie to a large interconnection makes the res✔ gradually connect lower voltage facilities and custoration process easier and smoother. A large interconnection
tomer load to maintain voltage stability. reactive
provides very stable frequency control and, to a lesser extent,
devices alone are insufficient to regulate voltage on an
voltage control. maintaining voltage and frequency in a
unloaded transmission system.
smaller island is considerably more difficult. in several such
✔ the availability of connection to a large interconnecinstances, operators found it necessary to manually shed load
tion makes frequency control and voltage control more
to prevent a complete collapse of the remaining system.
stable.
Operators must prioritize critical loads during restoration.
✔ shed load if need be to maintain stability within an
such loads, at the bulk power system level, include water and
island being restored.
sanitation system pumps, off-site power for nuclear generat✔ Prioritize critical loads during restoration.
ing stations, and airports.
the old cliché "expect the unexpected" is certainly appli- Regulatory Recommendations
cable to a system restoration effort. Despite the thoughtful and Standards
development of restoration plans, a number of unforeseen most of the recommendations that followed the postmortem
difficulties arose throughout the process, including damaged analysis of the blackout focused on preventing a cascading
generators, the inability to synchronize due to excessive volt- outage as opposed to recovering from one. recommendation
age disparities, and an inability to physically reach substations 29 from the u.s.-canada Power system Outage task Force,
due to industrial hazards spawned by the power outage. com- however, was as follows: "evaluate and disseminate lessons
munications was cited as an issue
in nearly all areas; communication
systems need to be able to function in the absence of the power
grid. similar flaws in emergency
plans were seen following hurricane katrina: officials anticipated
Quebec
being able to use cellular phones
Ontario
Ottawa
following the storm, but many cellular towers were inoperable.
VT
to summarize, the lessons
MI
Toronto
learned included the following
NH
priorities and steps:
Detroit
NY
✔ improve communications
MA
among responsible parCT
ties and communication
Toledo Cleveland
systems.
PA
New York
✔ Develop and maintain
OH
IN
a restoration plan, and
NJ
always be prepared to
IL
"expect the unexpected."
WV
✔ restoration begins by first
assessing the current state
figure 5. The area affected by 14 August 2003 blackout.
of the system.
32

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january/february 2014

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