Analysis of Small Disturbance Stability Regions of Power System Models with Real and Reactive Power Flows

Small-disturbance (SD) stability regions of power systems models incorporating bus voltage variation and the real and reactive power flow equations are analyzed. It is shown that SD stability regions may be disconnected. Furthermore, the regions contain fihnitely many components in a compact domain of interest. A sufficient condition is derived for a domain to have a unique SD stable solution of the real and reactive power flow equations. Other analytic properties of the SD stability regions are also investigated.