Exploration of the conceptual structure of voltage stability

An exploration is conducted of the differences which distinguish the state space of voltage stability from the familiar features of angle stability. The differences are major, mostly resulting from the presence of algebraic equations in the voltage problem. In voltage stability the load flow equations cannot be done away with as is customary in angle stability. The result is that in voltage stability a multiplicity of singular points and surfaces join the equilibria of all orders which are present in angle stability. As it turns out the singularities share the role of the equilibria and their stable and unstable manifolds as sources or sinks of trajectories and as boundaries of regions of behavior. Also singularities introduce events such as bifurcation points of various kinds which govern the entire complex of phenomena to a large extent. The plethora of these features, their roles and interactions, and the resulting structure of features and events are examined with respect to power systems and their generators.<<ETX>>