PROJECT TITLE :

State estimation and observability analysis for phasor measurement unit measured systems

ABSTRACT :

The synchronised phasor measurement units (PMUs) can give extremely accurate measurements that will improve the state estimation performance and observability. Though full observability based only on PMUs seems terribly impractical nowadays, it will be the case during a few years when these devices become commonplace equipment at substations. This paper compares the performances of three state estimation formulations, in terms of the convergence properties and also the variance in the estimated states. Phasor measurements, furthermore zero injections, are incorporated and either rectangular or polar coordinates will be used to represent the bus voltage and branch current phasors measured by PMUs. Current phasors in polar coordinates could give rise to ill-conditioning problems, which are resolved by conversion into rectangular coordinates format, using the uncertainty propagation theory. The behaviour of the weather within the measurement Jacobian matrix, as a result of of this measurements, is investigated for attainable sick-conditioning of the state estimator coefficient matrix. A non-iterative topological??numerical algorithm is proposed for observability checking and restoration in case of observability loss. The proposed algorithms are demonstrated with the IEEE 14-bus and IEEE 118-bus systems.