M.A. Thesis:

Optimal location and parameter tuning of power system stabilizers(PSS) in Multi-Machine power systems using Fuzzy Logic and PSO Algorithm

In most industrialized societies and even in developing countries, along with the rapid growth of electric energy, large interconnected networks have been made and developed. The need for reliable energy and the optimal use of energy resources Necessitate the need for interconnection of area networks. Therefore, the study of the dynamic stability of multi-machine power systems against disturbances has been one of the important issues of today's interconnected networks. Low frequency oscillations, which are referred as electromechanical oscillations of power system, are one of the important dynamical problems of the power system. It causes oscillations in rotor angle of the generators in network, that is related to the mechanical mode of the generators and these frequencies are about 0-2.5 Hz. Power system stabilizers usually used to damp out low-frequency oscillations. There are two important problems while using such controllers, generally: first, select the optimal location to PSS installation, and second, PSS parameters adjustment with the aim of attenuation increase in network's low frequencies oscillation modes. optimal placement is done, in order to optimal improvement of power systems damping, in addition to the PSS parameter adjustment. PSS parameters adjustment using PSO algorithm, contain three parts: real part of eigenvalue, damping ratio and generator speed varying by considering the weight among them. PSS position determined by detecting critical modes and first and second eigenvalues sensitivity. PSS parameters are adjusted using Particle Swarm Optimization algorithm (PSO), and using fuzzy algorithm optimal location for the PSS is determined, by acquisition eigenvalues and damping ratio and considering some fuzzy rules to guarantee the stability. simulation results on 4-machine power system show the desirable performance.

Keywords: power system stabilizer, multi-machine power system, optimal placement of power system s