Flexible AC transmission

The operation and components of the flexible AC transmission system (FACTS) are described. FACTS, designed to overcome the limitations of the present mechanically controlled AC power transmission systems, uses reliable, high-speed power electronic controllers. Its benefits are examined. These include greater control of power, so that it flows on the prescribed transmission routes; secure loading of transmission lines to levels nearer their thermal limits; greater ability to transfer power between controlled areas, so that the generation reserve margin may be reduced; prevention of cascading outages by limiting the effects of faults and equipment failure; and damping of power system oscillations