BIFURCATIONS, CHAOS, AND CRISES IN VOLTAGE COLLAPSE OF A MODEL POWER-SYSTEM

Bifurcations occurring in power system models exhibiting voltage colla pse have been the subject of several recent studies. Although such mod els have been shown to admit a variety of bifurcation phenomena, the v iew that voltage collapse is triggered by possibly the simplest of the se, namely by the (static) saddle node bifurcation on of the nominal e quilibrium, has been the dominant one. The authors have recently shown that voltage collapse can occur ''prior'' to the saddle node bifurcat ion. In the present paper, a new dynamical mechanism for voltage colla pse is determined: the boundary crisis of a strange attractor or synon ymously a chaotic blue sky bifurcation. This determination is reached for an example power system model akin to one studied in several recen t papers. More generally, blue sky bifurcations (not necessarily chaot ic) are identified as important mechanisms deserving further considera tion in the study of voltage collapse.