Analysis of the inter-area mode phenomenon in power systems following large disturbances

The authors deal with the analysis of the inter-area mode phenomenon in stressed power systems following large disturbances. The dynamic phenomenon of interest is dominated by the inertial effects and usually referred to as the inertial transient. In this phenomenon, following a large disturbance, a small group of generators close to the fault location are severely disturbed initially. As the transient progresses, the weak synchronizing forces in the system dominate. When instability occurs, it takes place as a separation of a large group of generators (including the small group severely disturbed by the fault initially) from the rest of the system. The analysis reported attempts to develop a better understanding of the problem. It is shown that the inter-area mode phenomenon could occur as a result of a nonlinear interaction of the natural modes of oscillation in the system. A procedure to predict the onset of the inter-area mode is presented