A fuzzy power system stabilizer (FPSS) is developed using the concept of fu
zzy basis functions. The linguistic rules, regarding the dependence of the
plant output on the controlling signal, are used to build the initial FPSS.
Based on the Lyapunov's direct method, an adaptation rule is developed in
order to make the FPSS adaptive to changes in operating conditions of the p
ower system. The FPSS is designed for a cogenerator, and simulation studies
are based on a one machine-infinite bus model. Nonlinear simulations revea
l that the performance of the adaptive fuzzy power system stabilizer (AFPSS
) is better than the performance of a conventional (linear) power system st
abilizer (CPSS) and a fixed-parameter FPSS for a wide range of operating co
nditions.