Energy-sorted Prony analysis for identification of dominant low frequency oscillations

In modern power system, the large size areas are interconnected for better power pooling that results in increased system inertia. However, this makes power to flow over long distances and pushing tie lines to operate closer to their maximum capacity. Operating tie lines closer to maximum capacity increases the possibility of inter-area oscillations (0.1-1 Hz) between two areas and is dominating near high load density area. The modern power system with growing interconnection creates more challenges in inter-area stability analysis. This paper proposes energy-sorted Prony method for online identification of dominant modes corresponding to Low Frequency Electromechanical Oscillations (LFEOs) in highly interconnected power system using Phasor Measurement Unit (PMU) data. The proposed method overcomes the disadvantage of higher false alarm rate of basic Prony method. This disadvantage is due to trivial modes that get introduced because of higher order system used in basic Prony method. The proposed method introduces a new methodology that uses the energy-sorted Prony that calculates the energy of all modes and sorts them according to energy content, this reduces the higher false alarm rate. To verify the effectiveness of the proposed method, a test signal and a two-area, four-machine system are used and the simulated results are presented.