This paper presents two proposed control techniques implemented on both small and large-scale power systems. These techniques are fuzzy logic power system stabilizer followed by a proportional-integral controller(FLPSS-PI) ,and proportional-integral followed by a fuzzy logic power system stabilizer
(PI-FLPSS) . Two signals from the synchronous machine are chosen as inputs
to the proposed controller, deviation in speed and deviation in speed derivative. The effectiveness of the proposed FLPSS-PI , and PI-FLPSS are demonstrated by the results of a gigital computer simulation of a small and a large-scale power systems. A comparative study is made between the performance of the two proposed controllers .