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Contact Person: Trond Toftevaag (Trond.Toftevaag@sintef.no)
Nordic PhD course on Wind Power (June 2005), Smøla 6 – 10 June 2005.
Problem for final examination.
Small-Signal and Transient Stability and Control
Establish a dynamic model of a two-area, 4 machine, power system similar to the system given
on page 813, Ref. [1]. Use PSS/E, SIMPOW®, Sim Power Systems (Matlab/Simulink) or
similar.
1. Steady state analysis
Perform steady state analysis, and check that the initial system state corresponds to the one
given in ref[1] (at least approximately).
2. Small-signal stability – manual excitation control
Perform small-signal stability analysis of the system with all four generators on manual
excitation control (compute the eigenvalues of the system state matrix).
Determine the frequencies, damping ratios, and mode shapes of the rotor oscillation modes.
(Same assumptions as given in (a) on page 814 in Ref. [1]).
3. Small-signal stability – automatic excitation control
Determine the eigenvalues, frequencies, and damping ratios of rotor oscillations when all four
generators are equipped with automatic excitation control according to descriptions given in (b)
on page 814 in Ref. [1].
Compare with results in item 2. Analyse, comment, describe, and conclude.
4. Transient stability – automatic excitation control
Perform transient stability analysis of the system when all four generators are equipped with
automatic excitation control according to item 3 for the following contingencies:
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Line from bus #8 to bus #9 circuit #1 is disconnected
Temporary three-phase short-circuit on bus #7
Analyse results, describe, and comment. Focus on dynamic behaviour of generators with
respect to active power, rotor angle, field voltage, rotor speed (as a minimum).
Find CCT (critical clearing time) for the most “sensitive” generator(s).
Discuss and test possible means to obtain enhanced transient stability of the system for these
particular faults. Determine CCT and other important quantities in this context for the system
when possible stabilizing controls are implemented in the model.
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Establish a modified dynamic model of the above two-area, 4 machine, power system model,
where generator No 3 is replaced with a swing bus (slack bus), both in the steady state (power
flow) computations and in the dynamic simulations.
Nordic PhD Course on Wind Power
TT
2005-06-20
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5. Small-signal stability of modified system – automatic excitation control
Repeat the above item 3 for the modified system model.
Compare with results in item 3 (and 2). Analyse, comment, describe, and conclude.
6. Transient stability of modified system – automatic excitation control
Perform transient stability analysis of the modified system for the same contingencies as
described in item 4.
Describe, analyse results, and comment. Focus on dynamic behaviour of generators with
respect to active power, rotor angle, field voltage, rotor speed (as a minimum).
Find CCT (critical clearing time) for the most “sensitive” generator(s).
Develop/propose and test means to obtain enhanced transient stability of the modified system
for these particular faults. (Keyword: Power System Stabilizer (PSS)).
Determine CCT and other important quantities in this context for the modified system when
stabilizing controls are implemented in the model.
References:
[1]
Prabha Kundur: Power System Stability and Control.
Electric Power Research Institute. Power System Engineering Series.
McGraw-Hill, Inc. 1994.
Nordic PhD Course on Wind Power
TT
2005-06-20