  The most commonly used weighted least square state estimator in power
industry is nonlinear and formulated by using conventional measurements such as
line flow and injection measurements. PMUs (Phasor Measurement Units) are
gradually adding them to improve the state estimation process. In this paper
the way of corporation the PMU data to the conventional measurements and a
linear formulation of the state estimation using only PMU measured data are
investigated. Six cases are tested while gradually increasing the number of
PMUs which are added to the measurement set and the effect of PMUs on the
accuracy of variables are illustrated and compared by applying them on IEEE 14,
30 test systems.
