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Generic Power System Stabilizer

Implement generic power system stabilizer for synchronous machine

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  • Generic Power System Stabilizer block

Libraries:
Simscape / Electrical / Specialized Power Systems / Electrical Machines / Synchronous Machine Control

Description

Note

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.

Examples

Performance of Three PSS for Interarea Oscillations

Performance of Three PSS for Interarea Oscillations

Three Power System Stabilizers (PSS) models using Kundur's four-machine two-area test system.

Ports

Input

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Input port that accepts one of these two inputs:

  • The synchronous machine speed deviation dw signal (in pu)

  • The synchronous machine acceleration power Pa = Pm - Peo, which is the difference between the machine mechanical power and output electrical power (in pu)

Output

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Stabilization voltage, in per unit. Connect this output port to the Vstab input port of the Excitation System block that you use to control the terminal voltage of the synchronous machine.

Parameters

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To edit block parameters interactively, use the Property Inspector. From the Simulink® Toolstrip, on the Simulation tab, in the Prepare gallery, select Property Inspector.

Time constant, in seconds (s), of the first-order low-pass filter used to filter the block input signal.

Overall gain K of the generic power system stabilizer.

Time constant, in seconds (s), of the first-order high-pass filter used by the washout system of the model.

Numerator time constant T1n and denominator time constant T1d, in seconds (s), of the first lead-lag transfer function.

Numerator time constant T2n and denominator time constant T2d, in seconds (s), of the second lead-lag transfer function.

Limits VSmin and VSmax, in pu, imposed on the output of the stabilizer.

Initial DC voltage, in pu, of the block input signal. Specification of this parameter is required to initialize all states and start the simulation in steady state with vstab set to zero.

Select this option to display a plot of the frequency response of the stabilizer when you click the Apply button.

Select this option to plot the magnitude of the frequency response to plot, in dB.

Dependencies

To enable this parameter, select the Plot frequency response parameter.

Frequency range used to plot the frequency response of the stabilizer.

Dependencies

To enable this parameter, select the Plot frequency response parameter.

References

[1] Kundur, P., Power System Stability and Control, McGraw-Hill, 1994, Section 12.5.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced before R2006a

See Also

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