Digital and experimental study of voltage collapse and instability in power system

A model of a power system with load dynamics is studied by investigating voltage collapse phenomena and sustained oscillation with a fast exciter. In the case of voltage collapse, the reactive power demand at a load bus is slowly increased until the voltage magnitude sharply falls to a very low level. In the case of instability and sustained oscillation, the small signal voltage instability is studied at a particular point with a fast exciter having hard limits. It is shown that the divergent response eventually results in sustained oscillations when hard limits in the fast excitation system are imposed. The paper presents both digital simulation and experimental results. A brief introduction to bifurcation theory is also included in the paper for completeness.