Demand for electrical energy continues to grow steadily, and is particularly strong in those countries on the threshold of industrialization. Electricity grid upgrades can not keep pace with the growing energy demand due to economical and environmental considerations that electric utilities are facing today to extend their power systems. Due to this situation, operators are looking for ways to utilize the existing power systems more efficiently. Consequently, most of power systems, nowadays, are working with heavy loading conditions. These new highly stressed operating conditions of these power systems arises different forms of power system instability. This book looks at stressed modern power system together with integrated wind resources and the role of FACTS devices in enhancing voltage stability.