State reconstruction from a limited number of synchronized phasor measurements: Application to voltage instability detection

This paper deals with the performance of the wide-area monitoring previously proposed by the authors in [1], [2] for early detection of voltage instability, when a limited number of synchronized phasor measurements is available. This sensitivity-based scheme assumed that phasor measurements are sufficient in number and location for a state estimator to determine the voltages at all buses of the region prone to voltage instability. This paper demonstrates that the method still performs well when relying on bus voltages obtained from a state reconstruction procedure exploiting a limited number of synchronized phasor measurements which do not make the region of concern observable. The state reconstruction is formulated as the minimization, under constraints, of a weighted least square objective involving the available phasor measurements together with bus power pseudo-measurements relative to a reference state. The presented results relate to a 52-bus system with phasor measurements obtained from detailed time simulation of a long-term voltage unstable evolution triggered by a large disturbance.