FLEXIBLE AC TRANSMISSION-SYSTEMS (FACTS)

The paper reviews literature which addresses the application of Flexib le AC Transmission System (FACTS) concepts to the improvement of Power System utilisation and performance. It summarises literature on using high speed thyristor based control of HVAC power system elements to e nhance the power carrying capacity of existing transmission circuits w ithout compromising reliability. It describes a study system represent ative of existing power systems that has been developed to evaluate th e economic and technical issues of loading transmission lines to their thermal limits. Considered are two scenarios, a multi-line corridor a nd a long radial interconnection, where the issues addressed are trans ient and dynamic stability, power flow control, reactive support and v oltage stability. A benchmark. system is developed to validate perform ance of the more simple devices. It is concluded that FACTS devices ha ve the potential to significantly increase system stability margins th ereby increasing loading capability of existing transmission corridors such as between Scotland and England. Economic evaluations of the app lications reviewed in the literature show that FACTS devices are attra ctive when compared with the other methods of achieving similar perfor mance objectives.