DETECTING MULTIPLE SOLUTIONS IN STATE ESTIMATION IN THE PRESENCE OF CURRENT MAGNITUDE MEASUREMENTS

This paper investigates the observability problem when the network con tains current magnitude measurements. Use of these measurements may le ad to multiple solutions and therefore to the loss of unique observabi lity for certain measurement configurations. The paper proposes a simp le method based on the commonly used measurement residual covariance m atrix, in order to detect the possibility of multiple solutions for a given measurement set. The proposed test is simple to implement and us es the already available matrices and data structures of the commonly used weighted least squares state estimation programs. It can be utili zed as a planning tool during the initial stages of measurement system design as: well as an online observability analysis tool to enhance t he capability of the existing observability programs which can not pro perly process the current magnitude measurements. Numerical examples a re provided to demonstrate the performance of the proposed method on s ample power systems.