The CCEBC/EEAC method is an effective method in the quantitative analysis of power system transient stability. This paper provides a qualitative analysis of the CCEBC/EEAC method and shows that from a geometrical point of view, the CCCOI-RM transformation used in the CCEBC/EEAC method can be regarded as a projection of the variables of the system model on a weighted vector space, from which a generalized(-P)-(-δ) trajectory is obtained. Since a transient process of power systems can be approximately regarded as a time-piecewise simple Hamiltonian system, in order to qualitatively analyse the CCEBC/EEAC method, this paper compares the potential energy of a two-machine infinite bus system with its CCEBC/EEAC energy. Numerical result indicates their similarity. Clarifying the qualitative relation between these two kinds of energies is significant in verifying mathematically the CCEBC/EEAC method for judging the criterion of power system transient stability. Moreover, the qualitative analysis of the CCEBC/EEAC method enables us to better understand some important phenomena revealed by quantitative analysis, such as multi-swing loss of stability and isolated stable domain.
The objective of this paper is to analyze the stability of equilibrium manifolds for a ratio-dependent two-predators one-prey model. Some model results are presented first with the bifurcation without parame-ters method, and then the method was used to study bifurcation along the equilibrium manifold for the model. The model does not lose stability even when some equilibria are locally unstable because the equilibrium manifold is stable when treated as a whole. The ecological implications of the results are discussed.
