I. Introduction
DAMPING of oscillations in interconnected power system is essential for secure and stable operation of the system. Power System Stabilizer (PSS) is the most widely used device for resolving oscillatory stability problems [1]. The transfer function model of Conventional Delta-Omega Power System Stabilizer (CPSS) with input Delta-Omega is shown in Fig.1. $${V_{s}(S)\over \Delta \omega(s)}=K_{STAB_{i}}\left[{sT_{wi}\over 1+sT_{wi}}\right]\left[{1+sT_{1i}\over 1+sT_{2i}}{1+sT_{3i}\over 1+sT_{4i}}\right]\eqno\hbox{(1)}$$ where,
PSS number
stabilizer gain,
washout time constant,
time constants of the lead lag networks.
Transfer function model of delta-omega CPSS.