Bifurcations and loadability issues in power systems

This paper deals with bifurcations and loadability issues in power systems. A single machine system with dynamic state space represented by a set of differential algebraic equations is considered. It is emphasized that this small system can give a first step in understanding the issues discussed in this paper. Using system loading as a bifurcation parameter and considering two methodologies for calculating system equilibrium points - specification of a fixed terminal voltage and a voltage-controller reference - the incidence of voltage imposed by the machine in the system stability is studied. The results of this paper reveal that careful attention must be paid to all methodologies for calculating equilibrium points, as some may obscure likely solutions in the state space. In addition, a proper adjustment of a machine voltage-controller reference can be exploited to provide relief to a system when it is operating close to collapse.