Minimax approximation synthesis in PSS design by embedding gravitational search algorithm

This paper presents a new approach to formulate the conventional objective function into multi order polynomials. This work also gives an emphasis on a novel designing and tuning methodology of power system stabilizers (PSSs) over New England System (10 Generator, 39 bus). The intelligent technique based on Newton´s Law of gravitation and law of motion, Gravitation Search algorithm (GSA) is applied to find the optimal parameters of PSSs. A new minimax approach is employed to design the PSSs, where several run of eigenvalue analysis is performed and in each iteration maximum deviation between ideal phase lag and proposed design is calculated. Approach is to minimize the maximum deviation between both frequency responses. For each set of PSSs parameters, the correlation between settling time, over shoot of the rotor swing curves is formulated by using minimax approach. The efficacy of the proposed design is tested over a wide range of contingencies, perturbation and different system configurations. Comparative analysis of all polynomial designs are presented while solving each with GSA. The results show those polynomials of order one (linear) are found to be the best fit and show a robust response under all operating conditions.