Linear programming approach for state estimation incorporating phasor measurements

Abstract

This paper presents methodologies for incorporating phasor measurements into conventional state estimator. The angle measurements obtained from Phasor Measurement Units are handled as angle difference measurements rather than incorporating the angle measurements directly. Handling in such a manner overcomes the problems arising due to the choice of reference bus. Current measurements obtained from Phasor Measurement Units are treated as equivalent pseudo-voltage measurements at the neighboring buses. Two solution approaches namely normal equations approach and linear programming approach are presented to show how the Phasor Measurement Unit measurements can be handled. Comparative evaluation of both the approaches is also presented. Test results on IEEE 14 bus system are presented to validate both the approaches.978-1-4577-1510-5/11/$26.00 c 2011 IEEE

Analysis of Ill‐conditioning of hybrid state estimators in the presence of PMU measurements

“…Also, the gain matrix tends to become ill-conditioned as the system size increases. To overcome the numerical problems associated with SCADA based SEs, several techniques, like Peters and Wilkinson method [6], orthogonal decomposition [7,8], Levenberg-Marquardt algorithm [9], linear programming [10], and regularization method [11] have been explored by researchers. Approximate expres-sion for the condition number of the gain matrix was formulated in [6] and [12], and it was found that the injection measurements caused degradation in the numerical performance of the SE.…”