Fast transient stability estimation using a novel dynamic equivalent reduction technique

A new dynamic equivalent power system (DEPS) model for fast first swing transient stability assessment is proposed in this paper. The DEPS model makes use of the phenomenon that during a fault on a large power system, there are many generators that are only lightly disturbed when compared with severely disturbed machines. The method substitutes these less disturbed machines by one equivalent generator but allows some model parameters to become time dependent. The crucial feature is that a novel method of classification of the less disturbed machines based on a Taylor series expansion which achieves a very rapid assessment of first swing critical clearing time (CCT) has been developed. This method is fundamentally different from other published dynamic equivalent techniques, such as the extended equal area criterion method and the identification of coherent generators, and both reliability and efficiency are better. With this DEPS model the efficiency of the traditional first swing transient stability analysis could be fundamentally improved. Extensive tests performed on several IEEE test systems show that the proposed model is suitable for fast transient stability assessment in large systems