The dynamic stability of a system can be improved by providing suitably tuned power
system stabilizers on selected generators to provide damping to critical oscillatory
modes. Suitably tuned Power System Stabilizers (PSS), will introduce a component
of electrical torque in phase with generator rotor speed deviations resulting in
damping of low frequency power oscillations in which the generators are participating.
The input to stabilizer signal may be one of the locally available signal such as
changes in rotor speed, rotor frequency, accelerating power or any other suitable
signal. This stabilizing signal is compensated for phase and gain to result in adequate
component of electrical torque that results in damping of rotor oscillations and
thereby enhance power transmission and generation capabilities. State-space techniques
described under Dynamic Stability Studies or classical control theory such as Bode
plots, root locus techniques can be used to determine suitable parameters for power
system stabilizers.The design can then be verified with a transient stability analysis
for practical system disturbances.
A Typical Control Schematic Diagram of Power System Stabilizer
http://www.powerapps.org/PAES_Dynamic Stability Or Small Signal Stability Studies.aspx