Observability and state estimation of electrical power networks (sinusoidal signals)

The aim of this article is to extract the totality of determinable parameters (measured or deduced) of an electrical power network in stationary state, in view to estimate their true values. These systems, different from conservation-law systems, are described by linear and bilinear equations which involve the complex intensities Ir and Ic, the impedances Zr and Zc, and voltages across the associated branch Ur and Uc. An algorithm allowing one to determine those determinable parameters is presented; this algorithm is based on the number of measured and unmeasured variables, on their localization and on their interdependence. Close to this observability study, a method of state estimation applied to the observable sub-system is presented. This method allows, besides the true value estimation, to detect and localize possible defects on the instrumentation, by the analysis of normalized residues. Finally, these algorithms will be applied to an electrical system. 2002 Elsevier Science Ltd. All rights reserved.