Power oscillation damping in multi-machine power system using PSSs considering various load models

This paper studies the effect of Power System Stabilizers in damping of low frequency oscillations in a multi-machine power system with different load combinations. Various load models considered are constant impedance load, mixture of constant impedance and constant current load and mixture of constant impedance and constant power load. For this, a linearized model of multi-machine power system was developed. After forming state matrix, Eigen value analysis was carried out to find out low frequency local and inter-area modes of oscillations. For the optimal placement of PSS, participation factor analysis was carried out. The generator with highest participation factor is considered best candidate for the placement of PSSs. This analysis is carried out for two area (4-machines, 14 bus system) and multi area (16 machines, 68 bus, NY-NETS) system. The performance of PSSs in damping both local and inter-area modes of oscillations was found to be satisfactory.