Two level dynamic state estimator for electric power systems based on nonlinear transformation

A two level dynamic state estimator for electric power systems is proposed. The direct system measurements are transformed, using a nonlinear transformation, into another set of measurements such that the resultant estimation problem is suitable for two level calculations. The main computational load is performed at the low level subsystems, and the voltage estimates are obtained directly from this level. The upper level (co-ordination level) is responsible for calculating the rotation angle required to be added to the angles already estimated at the low level to refer all angles to the general slack busbar of the network. The proposed estimator is tested on the IEEE-30 busbar network. Results showed that the accuracy of this two level estimator is high, and it is compared with the case when the estimation is carried out on the global network. On the other hand, a significant reduction in computational time is achieved.<>