Hybrid state estimation of power system using conventional and phasor measurements

Abstract

State estimation is traditionally being done by using conventional measurements obtained from SCADA system. The measurements include voltage magnitudes, real and reactive power injection at the buses, and real and reactive power flow through the lines. With the advent of phasor measurement units (PMU), that provides synchronized voltage and current phasors at the PMU installed bus and the adjoining lines, a new chapter has been added to the state estimation process. This paper compares the conventional weighted least squares state estimation technique with the Hybrid state estimation technique that includes both conventional and synchronized measurements obtained from SCADA system and PMUs. No bus is taken as reference for Hybrid Estimator. Cartesian coordinate system is used to negate the problems faced when flat start or lightly loaded lines are considered. Tests are done on the standard IEEE 14-bus system. Results of both the methods are compared which shows that the Hybrid state estimation improves the precision of the estimates to a great extent.