A hybrid power system state estimator using synchronized and unsynchronized sensors

Summary This paper presents a hybrid state estimator based on measured data delivered by unsynchronized and synchronized sensors, taking into account their different refresh rates. The proposed algorithm is based on a reference‐free problem formulation, using Cartesian coordinates for both the phasorial measurements and the state vector. Each time that supervisory control and data acquisition measurements are updated, a nonlinear state estimator runs using asynchronously gathered measurements and a limited number of synchronized measurements. In between supervisory control and data acquisition scans, each time that phasor measurements are refreshed, a linear state estimation is executed. The proposed scheme processes separately the conventional and the phasorial measurements. The method is validated by simulation results on the IEEE 14 and 118 bus benchmark systems.