State estimation of power system based on SCADA and PMU measurements

A two stage state estimator (SE) of an Electric Power System (EPS) is presented in this paper. It combines SCADA (Supervisory Control and Data Acquisition) and PMU (Phasor Measurement Unit) measurements. This feature gives it more accuracy on estimation over conventional algorithms based on SCADA measurements and also the possibility to obtain dynamic information of the system behavior. In the first stage a nonlinear HSE (Hybrid State Estimator) is executed at every updating moment of SCADA measurements. The state is defined as the vector of complex bus voltages and it is estimated by WLS (Weighted Least Square) technique. The measurement vector includes SCADA measurements and PMU voltage measurements. In the second stage a nonlinear SE is executed at every updating moment of PMU measurements. The state is defined as the vector of complex branch currents and it is estimated by WLS technique. The measurement vector of this case includes only PMU voltage and current measurements. The performance of the proposed method is analyzed on a 17 bus system (IEEE 14 bus system modified). Results show the ability of the algorithm to track the voltage dynamic accurately.