Implement generic power system stabilizer for synchronous machine
This block requires that you have a Control System Toolbox™ license. Otherwise, trying to simulate a model containing this block produces an error.
The Generic Power System Stabilizer (PSS) block can be used
to add damping to the rotor oscillations of the synchronous machine
by controlling its excitation. The disturbances occurring in a power
system induce electromechanical oscillations of the electrical generators.
These oscillations, also called power swings, must be effectively
damped to maintain the system stability. The output signal of the
PSS is used as an additional input (
vstab) to the
Excitation System block. The PSS input signal can be either the machine
speed deviation, dw, or its acceleration power, Pa = Pm - Peo (difference
between the mechanical power and the electrical power).
The Generic Power System Stabilizer is modeled by the following nonlinear system:
To ensure a robust damping, the PSS should provide a moderate phase advance at frequencies of interest in order to compensate for the inherent lag between the field excitation and the electrical torque induced by the PSS action.
The model consists of a low-pass filter, a general gain, a washout high-pass filter, a phase-compensation system, and an output limiter. The general gain K determines the amount of damping produced by the stabilizer. The washout high-pass filter eliminates low frequencies that are present in the dw signal and allows the PSS to respond only to speed changes. The phase-compensation system is represented by a cascade of two first-order lead-lag transfer functions used to compensate the phase lag between the excitation voltage and the electrical torque of the synchronous machine.
The time constant, in seconds (s), of the first-order low-pass
filter used to filter the block's input signal. Default is
The overall gain K of the generic power system stabilizer. Default
The time constant, in seconds (s), of the first-order high-pass
filter used by the washout system of the model. Default is
The numerator time constant T1n and denominator time constant
T1d, in seconds (s), of the first lead-lag transfer function. Default
The numerator time constant T2n and denominator time constant
T2d, in seconds (s), of the second lead-lag transfer function. Default
The limits VSmin and VSmax, in pu, imposed on the output of
the stabilizer. Default is
The initial DC voltage, in pu, of the block's input signal.
Specification of this parameter is required to initialize all states
and start the simulation in steady state with
to zero. Default is
If selected, a plot of the frequency response of the stabilizer is displayed when you click the Apply button. Default is cleared.
The Magnitude in dB parameter is not visible if the Plot frequency response is not selected. If selected, the magnitude of the frequency response is plotted in dB. Default is selected.
The Frequency range parameter
is not visible in the dialog box if the Plot
frequency response is not selected. Specify the frequency
range used to plot the frequency response of the stabilizer. Default
Two types of signals can be used at the input
The synchronous machine speed deviation dw signal (in pu)
The synchronous machine acceleration power Pa = Pm - Peo (difference between the machine mechanical power and output electrical power (in pu))
The output is the stabilization voltage (in pu) to connect to the Vstab input of the Excitation System block used to control the terminal voltage of the synchronous machine.
See the help text of the
 Kundur, P., Power System Stability and Control, McGraw-Hill, 1994, Section 12.5.