IEEE Power & Energy Magazine - January/February 2014 - 43

Field Voltage
Terminal Voltage

january/february 2014

30.000

27.000

24.000

21.000

18.000

15.000

12.000

Time (s)

Summary
restoration actions involve very unusual conditions, especially for local generation used as a bsr. important considerations for assuring that restoration plans are realizable
include the ability to operate in islanded conditions with
stable frequency and voltage control, the availability of synchronizing equipment at key substations to permit paralleling
of separate sections, and the validity of assumptions used to
assess the ability of synchronous generators to operate at the
unusual points of their capability required during the restoration period.
restoration actions performed to recover from a
blackout may vary from those determined in the restoration studies. restoration plans are based on a given set of
assumptions, such as the available transmission, the amount
of cold load to be picked up, and the many other conditions
discussed in this article. although actual conditions could
differ from these assumptions, restoration studies provide
value by demonstrating the logic behind particular steps
being taken, such as the reasoning behind the choice and
sequence of operator actions and the expected results of
those actions. with this understanding, the operating staff
will be able to adapt to differences in the actual versus the
assumed conditions.
this article has described restoration operations and
the studies that should be part of a restoration planning
process. in particular, it attempted to describe technical
issues such as system dynamics and control aspects of the
black-start process. this overview should be helpful to utility staff involved in the development of restoration plans.
development of thorough restoration plans and the testing of those plans through simulation and drills will help
to minimize disruption of service to loads and the risk of
damage to equipment following partial or total power system blackouts.

9.000

6.000

3.000

Speed Deviation

0.0

motor reactive power, electrical torque, and motor slip are
shown. note the dip in motor terminal voltage and that the
demand for reactive power rises during the period following the lowest voltage at the motor terminals. the motor's
air gap torque increases significantly during the acceleration
period, as expected, to overcome the mechanical load torque
that opposes developed electromagnetic torque.
the dynamic response of the bsU during the starting of
this large induction motor is shown in Figure 8. the performance of the excitation system is shown as it works to
control the bsU's terminal voltage. note the fast response
and large field forcing applied to pull up the machine terminal voltage from the dip caused by the large reactive power
demand imposed by the starting motor. the unit also sees
a significant voltage rise caused by the rapid reduction in
reactive power as the motor locks in to its operating speed.
electric power demand also increases during this period
as the motor accelerates and moves toward its steady-state
operating point.

figure 8. Dynamic response of the BSU as the large
induction motor is started: field voltage, terminal voltage,
and speed.

For Further Reading
M. M. adibi, "power system restoration, methodologies, and
implementation strategies," IEEE Series on Power Engineering, p. M. anderson, ed., 2000.
ieee Committee report, "system restoration-deploying
the plan: current operational problems working group,"
IEEE Trans., pp. 4623-4671, nov. 1982.
J. w. Feltes and C. grande-Moran, "black start studies for
system restoration," presented at the 2008 ieee power and energy society general Meeting, pittsburgh, pa, 20-24 July 2008.
J. w. Feltes, C. grande-Moran, p. duggan, s. Kalinowsky,
M. Zamzam, V. C. Kotecha, and F. p. de Mello, "some considerations in the development of restoration plans for electric utilities serving large metropolitan areas," IEEE Trans.
on Power Systems, vol. 21, no. 2, pp. 909-915, May 2006.
ieee Committee report, "new approaches in power
system restoration," IEEE Trans. on Power Systems, vol. 7,
no. 4, pp. 1428-1434, nov. 1992.
M. henderson, e. rappold, J. w. Feltes, C. grande-Moran,
d. durbak, and o. bileya, "addressing restoration issues for
the iso new england system," 2012 ieee power and energy
society general Meeting, san diego, Ca, July 2012.

Biographies
James Feltes is with siemens power technologies international (siemens pti), schenectady, new york.
Carlos Grande-Moran is with siemens power technologies international (siemens pti), schenectady, new york.
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