Optimal placement of FACTS devices for voltage stability using line indicators

Optimal location of FACTS (Flexible AC Transmission System) is very important for static voltage stability. This paper presents the determination of most unstable bus of system using P-V curve and eigenvalue analysis and the critical line using the stability indices. Voltage collapse indicators indices give exact information about the stability condition of a system and also determine the most insecure bus of the system. The line indices are evaluated for IEEE 14 bus system and critical line is found where the index reaches its maximum value. PSAT (power System Analysis Toolbox) software is used for Continuation Power Flow (CPF)) and the results shows that optimal placement of Unified Power Flow Controller (UPFC) significantly increase the loadability margin and stability of system.