Bacteria Foraging: A New Tool for Simultaneous Robust Design of UPFC Controllers

Robust tuning of lead-lag type controller used for regulating FACTS control signal to improve dynamic stability has been an area of interest in research. This paper presents a new approach based on the foraging behavior of E.coli Bacteria in the human intestine, to optimize simultaneously three constants each of four lead-lag type UPFC controller present in a single machine infinite bus (SMIB) power system. For the tuning purpose, a multi-objective cost function is formulated that accounts for damping factors and ratios of various system modes for a wide range of operating conditions. Robustness of the proposed tuning method is shown by transient stability analysis of the system time domain simulations when subjected to disturbances at different operating conditions.