Identification of dominant low-frequency modes in ring-down oscillations using multiple Prony models

This study presents a simple approach to modify the Prony algorithm to extract dominant low-frequency modes present in ring-down oscillations in power systems. The proposed approach is based on the observation that true modes present in the ring-down oscillations appear consistently, irrespective of the order of the Prony model. It is shown that the consistently appearing modes can be extracted using a sorting method. The improved Prony algorithm which has the feature of extracting only the true modes present in the input signal is utilised to propose an oscillation monitoring algorithm in this study. The suitability of the proposed oscillation monitoring algorithm for real-time monitoring of low-frequency inter-area oscillations is demonstrated using synthetic signals and simulated signals of different test systems.