A fuzzy controller has been designed and implemented to enhance the overall power system stability. To achieve good damping characteristics over a wide range of operating conditions, speed deviation and acceleration of a synchronous generator are chosen as the input signals to the fuzzy controller. The stabilizing signal is determined according to the nonlinear fuzzy membership functions depending on the speed and acceleration states of the generator. The design and digital simulation studies are carried out on a one-machine infinite bus power system. The design is implemented on a 5 kVA generator in the Power System Laboratory with an IBM-486 computer associated with A/D and D/A converter acting as the real time controller. The implementation study is carried out on both single-machine and two-machine infinite bus power systems respectively. Studies of simulation and implementation show that the proposed fuzzy controller is very effective  --- Conference held Vancouver, British Columbia, Canada, 13-16 September, 1993