The conventional power plants of 1950s were equipped with continuously acting automatic voltage regulators to improve the transient stability of system. The high gain of these voltage regulators has a destabilizing effect on power system. The power oscillations of small magnitude and high frequency, which often persisted in power system, present the limitation to the amount of power transmitted within the system. Improved performance has been achieved by adding damping to the system by employing power system stabilizers (PSS). Conventionally a lead- lag PSS was used to achieve this objective but has certain demerits like sluggish response etc. The use of Artificial intelligence has gain momentum now days in power system. This book gives the overview of various artificial intelligence techniques used in PSS till now and a case study based on fuzzy logic based PSS, its performance for a grid connected synchronous generator, and finally the effect of type of membership functions on PSS. This is my second book in this area. Its a perfect book for the students, researchers and industry related experts to explore the possibility of AI techniques in power system stability problems.