ABSTRACT
AC transmission circuits are mostly composed of passive elements having very little controllability. Therefore, when the load increases, existing network control methods are not sufficient to properly accommodate increased power flows. As a result, certain lines are more heavily loaded and stability margins are reduced. Due to the difficulty of controlling power flows by existing methods, new types of power electronic devices called FACTS (Flexible AC Transmission System) are used to control existing T&D networks. FACTS devices are installed at all voltage levels up to 800 kV.
