Frequency domain analysis of power system forced oscillations

A frequency domain approach is used to analyse power system forced low frequency oscillations. The gain characteristics of a closed loop transfer function, which reflects the effect of disturbances on power angle oscillations, are shown to be crucial in identifying the frequency ranges in which amplified oscillatory disturbances can occur. It is shown that tuning power system stabilisers (PSS), based on eigenvalue analysis, lack the insight gained from the explicit evaluation of the gain response. The authors also propose a dynamic gain reduction scheme which decouples the negative damping effects while accentuating the stabilising effects of the PSS derivative feedback. It is shown that a considerable reduction in the tie-line mode oscillations can be achieved