BIFURCATION AND CHAOS IN POWER-SYSTEMS

A detailed example of a power system model with load dynamics is studi ed by investigating qualitative changes or bifurcations in its behavio ur as a reactive power demand at one load bus is increased. In additio n to the saddle-node bifurcation often associated with voltage collaps e, we find other bifurcation phenomena which include Hopf bifurcation, cyclic fold bifurcation, period doubling bifurcation, and the emergen ce of chaos. The presence of these dynamic bifurcations motivates a re -examination of the role of saddle-node bifurcations in the voltage co llapse phenomenon. In fact, simulation results suggest that voltage co llapse may take place before the reactive power demand is increased to the system steady-state operating limit where a saddle-node bifurcati on is detected. We also consider the role that the algebraic constrain ts imposed by some load models may play in the global analysis of the attractors of the system. Implications for power system operations are drawn.