A Multi-Band Power System Stabilizer (MB-PSS) is developed in this paper to get a moderate phase advance at all frequencies of interest in order to compensate for the inherent lag between the field excitation and the electrical torque induced to ensure robust oscillation damping. Its performance is compared with two conventional power system stabilizers (PSS) used to add damping to the rotor oscillations of the synchronous machine by controlling its excitation currents during disturbances. One of them is fed from acceleration power signal and called (Pa-PSS) and the other is fed from speed deviation signal and called (dω-PSS). Digital time responses simulations of the nonlinear system performance during and after severe disturbances have proved effectiveness of the developed (MBPSS). The (MB-PSS) is found to be more effective than those with (dωPSS) and (Pa-PSS). The (MB-PSS) act very fast to follow transient system conditions and to restore its stability subsequent to severe disturbances.