Climate change and growing concern of limited fossil fuel reserves and prices have led to the necessity of creating renewable and sustainable energy sources. Recently, Wind energy is attracting more attention from researchers and even utilities due to its benefits as a clean and abundant source of energy. Moreover, it is worth noting that Power demand has increased substantially while the expansion of power transmission lines has been severely limited due to inadequate resources and environmental restrictions. As a consequence, some transmission lines are heavily loaded and the system stability becomes a serious problem. FACTS controllers have been used for solving various power system control problems, enhancing power system stability in addition to their main function of power flow control. In this book a comprehensive and intensive study of a wind farm connected to the grid has been proposed. The aim of this book is to investigate the system stability of a wind farm connected to medium voltage grid in different operating conditions and to investigate the behavior of the system when using a Static Var Compensator (SVC) and Static Synchronous Compensator (STATCOM).