A state estimator including conventional and synchronized phasor measurements

This paper presents an effective weighted least square formulation for the solution of the state estimation problem, considering conventional as well as synchronized phasor measurements. The proposed algorithm is based on a reference-free formulation, using both rectangular and polar coordinates for branch current phasor measurements, and alleviates any numerical problems encountered during initialization stage of the state estimation algorithm. Analytical equations are provided for the conventional and the phasor measurements and their corresponding partial derivatives with respect to state variables. The proposed algorithm is tested with a seven bus system and is compared with the traditional state estimator. Simulation results show that the proposed algorithm improves the precision greatly and gets better behavior as compared with the traditional state estimator.

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► We develop a hybrid state estimation algorithm for power systems including PMUs.
► All bus phase angles are considered with regard to the reference dictated by GPS.
► Current phasors can be modelled in rectangular or polar form.
► Modelling current phasors in rectangular coordinates alleviates ill-conditioning.
► Inclusion of PMU measurements greatly improves its performance.