Bounds of Estimated States Based on Line Parameter Uncertainties

Abstract

The accurate monitoring and control of power systems relies heavily on the power system topology, the accurate models of every component and especially on the accurate representation of the power system transmission lines. The parameters that characterize the existing transmission lines (resistance and reactance) are stored in the control center database and are used in several applications, such as the state estimator, power flow analysis, and voltage stability analysis. The parameters’ values may be subjected to errors and their exactness can be refined using Phasor Measurement Unit (PMU) measurements from the two ends of the transmission lines (in case of pi model). In such a case, the calculated line parameters will have associated a maximal error relative to the PMU-chain measurement uncertainty. In this paper, the standard uncertainty of the calculated line parameters is used for assessing the intervals linked to the estimated states. The proposed approach is validated using the IEEE 14-bus system where it is demonstrated that the calculated intervals always encompass the true state of the system.