A nonlinear observability formulation for power systems incorporating generator and load dynamics

Traditionally, observability in power systems is derived from the state-estimation problem and is based on a non-linear algebraic model of the system. This measure of system observability focuses on the sensitivity of the system measurements to the change In the system states. Since the model of the system used is an algebraic model, describing the flow of power throughout the network, the non-linear dynamics of the system related to generator performance and non-linear components are ignored. The proposed observability formulation accounts for these non-linearities and provides a more comprehensive observability determination with the ability to track the observability determination of the system along the trajectory of the dynamic system states. The observability formulation of the system is sensitive to the trajectories of the system states, and the regions of the statespace where the system observability is lost are presented. A qualitative analysis for the limits of the observability formulation is presented for a 3-bus power system.