Low Frequency Oscillation at a Multi Machine Environment by Using UPFC Tuned Based on Simulated Annealing

Unified Power Flow Controller (UPFC) is one of the most viable and important Flexible AC Transmission Systems (FACTS) devises. Application of UPFC in single machine and multi machine electric power systems has been investigated with different purposes such as power transfer capability, damping of Low Frequency Oscillations (LFO), voltage support and so forth. But, an important issue in UPFC applications is to find optimal parameters of UPFC controllers. This paper presents the application of Unified Power Flow Controller (UPFC) to enhance dynamic stability of a multi-machine electric power system. A supplementary stabilizer based on UPFC (like power system stabilizer) is designed to reach the defined purpose. An intelligence optimization method based on Simulated Annealing (SA) is considered for tuning the parameters of UPFC supplementary stabilizer. Several nonlinear time-domain simulation tests visibly show the ability of UPFC in damping of power system oscillations and consequently stability enhancement