Effects of Power System Stabilizer on Inter-area Oscillation in a Longitudinal Power System

Modern power systems bring many benefits but they may also contain many potential problems such as low-frequency oscillations which threat the stability of the system. The main objective of this paper is to report a preliminary study of the effects of power system stabilizer on the small-signal stability and the damping of low-frequency oscillations of a power system which is under fast development and has a longitudinal grid pattern. Spontaneous low-frequency oscillations are potential to occur in the exchange of regional power flow under normal operation, especially in the operation of an interconnected power system with a longitudinal network structure. The inter-area oscillations often have features of being low frequency, lightly damped, and affecting relatively more generating units located in multiple areas. The method of eigen-analysis is utilized to perform the study of the inter-area oscillations with an emphasis on the oscillation mode with low frequency and light damping. The eigenvalue, eigenvector, and participation factors associated with the inter-area oscillation mode are calculated in details and possible locations of PSS are chosen for study accordingly. The results demonstrate for the PSS the effectiveness in damping inter-area oscillatory modes and thus the contribution to the improvement of stability of the study system.