A Hybrid State Estimator with Pseudo-Flows and Pseudo-Injections

Abstract

The paper presents the hybrid state estimator that incorporates the conventional measurements from the Supervisory Control And Data Acquisition (SCADA) system and the synchronized phasor measurements available from Phasor Measurement Units (PMUs). The voltage and current phasors are utilized to obtain pseudo-measurements of power flows and injections. The derived pseudo-measurements are combined together with the voltage phasors and the conventional measurements as inputs for the iterative state estimator based on the Weighted Least Squares method with the addition of equality constraints for zero-injections. The proposed formulation was tested on the IEEE test systems with 14, 30, 57 and 118 buses. The Croatian transmission power system model with the deployed PMUs was used as an example of the real power system. The simulation results were compared with another hybrid state estimator and with the classical solution that does not take advantage of the synchronized phasor measurements. The developed hybrid state estimator provides higher accuracy of the estimated system state along with improved filtering of measurement errors.