Wide area measurement-based coherency identification for real-time transient stability assessment

Fast and accurate coherency identification is necessary for the equivalence transform when real-time analyzing the transient stability of power system. In this paper, a novel method of coherency identification based on Wide Area Measurement (WAMS) is presented. By analyzing the dynamic process of the system, a comprehensive variable is obtained by giving angle, angular velocity and angular acceleration time-varying weights to better reflect the difference of real-time dynamic behavior among generators. Thus, the coherency identification method based on comprehensive variable is put forward. Besides, an evaluation method based on Davies-Bouldin´s Index (DBI) is presented to real-time assess the rationality of clustering result. The speed and accuracy of the proposed scheme is verified by simulations on IEEE standard 39-bus 10-unit system.