Dominant mode identification for low frequency oscillations of power systems based on Prony algorithm

Once the power system low frequency oscillation occurs, the operators desire to find out the dominant mode LFO so as to take measures to suspend it. This paper proposes an identification method for dominant mode of LFO based on Prony algorithm in wide-area measurement system (WAMS). The presented method contains three steps, the first step is preprocessing of Prony analysis result, the second step is the dominant mode identification, and the third step is the grouping of different generators according individual generator´s frequency and phase information. Among the dominant mode identification step, three indexes are proposed to select the dominant mode. The first one is the ratio of amplitude and damping ratio; the second one is mode energy and the third one is the amplitude of sinusoidal decay mode after a period of oscillation. The simulation results in a two-area-four-machine benchmark system and 10 generator 39-bus New England system by DSATools demonstrate that the proposed method has strong adaptability to noise, i.e., the method has good performance of identification.