Modal Analysis of a Renewable Power Generation Station Based on the Equivalent Decoupling

In this paper, a single-unit-based modal analyzing method for the renewable power generation station (RPGS) is proposed and the characteristics of the mode shapes (MSs) and participation factors (PFs) are analytically studied. First, under the condition that the units are of similar dynamic models, expressions for the MS and PF matrices of the station with respect to the MS and PF matrices of a single unit and the network parameters are derived. Then, it is found that for each of the modes, the MSs and PFs can be formed by the MSs and PFs of a single unit and the eigenvalues and eigenvectors of the network reactance matrix. Therefore, a single-unit-based modal analysis method is proposed. Second, it is further revealed that under the condition of similar dynamic models, the activities and participations of the same state variable of each of the units to a single mode are mainly determined by the network topology. In addition, the condition and mechanism for the phenomenon that participations of each of the units to the dominant mode are nearly identical are also analytically demonstrated. Finally, effectiveness of the method proposed and conclusions drawn is verified via study cases.