A review of new innovations in power system control

Financial and environmental constraints have afflicted power systems throughout the world. Environmental pressures have forced the retirement and nonreplacement of power station close to urban load centres as well as making it more difficult and expensive to establish additional transmission lines to supply these large load centres. All these factors have altered the method of power system operation from the manner originally planned. Larger amounts of power are being conveyed over the interconnections. This results in transmission bottlenecks, under-utilisation and sometimes unwanted extra loading of transmission facilities. FACTS (Flexible AC Transmission Systems) specially designed to introduce more “flexibility” both in normal and emergency operation of an electric power system have been proposed. The flexibility is related to the direct control (both local and centralised) of both active and reactive power. The main aim is to increase the utilisation of existing facilities even to its thermal limits (without sacrificing reliability) in order to reduce the difficulties in installing new transmission lines and to permit larger transfer of low-cost electricity through interconnected areas or countries. This paper provides a review of the basic concepts of FACTS, the possible FACTS options currently available, the development and demonstration efforts in USA and Europe and the cost benefit analysis of such an installation. The paper concludes that FACTS technology is now available for use, although the cost may be prohibitive initially