Wind generation connection to a power system affects its steady state and transient stability. This effect increases with the increase of wind generation capacity penetration. In this book, determining the optimal location of FACTS devices to solve the problem associated with wind penetration in power systems is carried out by using genetic algorithm optimization technique. The first part of the study in this book is devoted to the selection of suitable FACTS type and ranking method. After the selection is fulfilled, the second part, which deals with maximizing the wind energy penetration of the system by using series FACTS devices in certain range, is performed under several topologies of system. Other studies are carried out to increase wind penetration based on several models of wind generation. Also, comparison between wind penetration increases in same location or in several locations is carried out in this book. Results showed that series FACTS devices in certain range are able to solve these problems associated with wind penetration in power systems with acceptable cost saving. Examination of the proposed approach is carried out on several IEEE test systems.