This book introduces FACTS technology and VSC-based FACTS controllers. It describes the Newton method and its application for solving the power-flow problem. Subsequently, the book presents the Newton power-flow modeling of the static synchronous series compensator, unified power-flow controller, interline power-flow controller, generalized unified power-flow controller, and static synchronous compensator. It also depicts a unified Newton power-flow model of AC systems incorporating multiterminal VSC-HVDC systems with PWM control schemes. Numerous case studies are carried out for validation of the models.