A Novel Graphical Method for Thévenin Equivalent Determination based on 3D Plane Fitting

This paper presents a novel technique for online Thévenin Equivalent (TE) parameters determination for power systems. A graphical method for deriving TE parameters using online Phasor Measurement Unit (PMU) measurements is presented. The method is developed based on plane fitting in the three-dimension space of quantities derived from the PMU measurements. A least squares estimation method is also presented for estimating the TE based on the same quantities and mathematical basis. Approaching TE from graphical and analytical aspects is useful for understanding of such a powerful tool and its possible application for grid analysis. Both of the proposed methods have the ability to accommodate large number of measurements in each calculation step with low computational power requirements. The proposed method performance is tested on IEEE 30-bus system, the result shows that the proposed method can track TE equivalent parameters.