Determination of critical zones for voltage instability in power systems

It is shown that voltage collapse in power systems can be associated with the emergence of impulse modes in the post-bifurcation trajectory of the system represented in descriptor form. The local intensity of voltage instability at load buses can be characterized by the participation factors obtained through eigenanalysis of the Jacobian matrix of the system which correspond to voltages at load buses. It can also be quantified by sensitivity analysis of total generated reactive power with respect to loading parameters of the system. Relative distribution of the participation and sensitivity factors among load buses depends on the load characteristics and loading patterns. They are greatly affected by the transition of the generators into a constant reactive power mode. Simulation results are presented.