Volume 2 - Issue 3, May - June 2026

Flexible AC Transmission System (FACTS) controllers are modern power electronic devices used in electrical power systems to improve transmission efficiency, voltage stability, and power quality. In today’s power systems, increasing electricity demand, renewable energy integration, and transmission congestion create many operational challenges. Conventional transmission systems are unable to provide flexible control during sudden load changes and disturbances. FACTS controllers solve these problems by controlling voltage, impedance, and phase angle of transmission lines. This paper explains the working principle, classification, applications, advantages, and limitations of FACTS devices. Major controllers such as Static VAR Compensator (SVC), Static Synchronous Compensator (STATCOM), Thyristor Controlled Series Capacitor (TCSC), Static Synchronous Series Compensator (SSSC), and Unified Power Flow Controller (UPFC) are discussed in detail. The role of FACTS controllers in smart grids, renewable energy systems, and power quality improvement is also explained. FACTS technology helps in reducing transmission losses, improving voltage profile, increasing power transfer capability, and enhancing system reliability. Although FACTS devices have high installation costs, their technical and economic benefits make them an important technology for future power systems and smart grids.

Apurva Ramchandra Patil,"FACTS Controllers for Power Quality Improvement and Power System Stability Improving Power System Performance Using FACTS Devices" International Journal of Advanced Multidisciplinary Research and Educational Development, V2(3): Page(367-371) May-June 2026. ISSN: 3107-6513. www.ijamred.com. Published by Scientific and Academic Research Publishing.