Electric Power Network State Tracking From Multirate Measurements

This paper proposes a novel tracking state estimator to process both fast-rate synchronized phasor and slow-rate supervisory control and data acquisition (SCADA) measurements. The former are assumed to be in limited number. The latter are exploited as and when they arrive to the control center. In order to restore observability, after each execution of the tracking state estimator, forecast SCADA measurements are used as pseudo-measurements in the next estimation. An event detection analysis allows assessing if the system is in quasi-steady-state. If so, an innovation analysis is performed to identify and eliminate erroneous SCADA measurements. The system state is computed by Hachtel's augmented matrix method. The option of exploiting time-tagged SCADA measurements is also considered. The method is illustrated through detailed dynamic simulations of a test system evolving toward voltage collapse, with and without emergency control.