The effect of instrument transformer accuracy class on the WLS state estimator accuracy

The measurement chain of the power system consists of various components introducing their associated uncertainty to the measured quantity. Although, it is important to identify and quantify the individual uncertainties of the measurement chain components and consequently the combined measurement chain uncertainty, it is nearly impossible to do this for all the components. In this paper a simplified measurement chain is considered that consists of the instrument transformer and the measurement device. The importance of considering the accuracy class of the instrument transformer is underlined by examining the effect of the instrument transformer accuracy class on the performance of a conventional and a hybrid state estimator performance. The two state estimators are used in the IEEE 118 bus system.