Thevenin equivalent circuit parameter estimation for the PCC upstream system

The Thevenin equivalent circuit parameters for the upstream system seen at a load bus plays an important role in the power system operation and planning. In order to accurately estimate the Thevenin equivalent parameters for the upstream supply system, an estimation method not requiring synchronized measurement is used in this paper. The characteristics of the probability curves of load voltage and impedance fluctuations have been analyzed, based on which the data selection criteria has been established. The field measurement data from different substations are processed by the proposed methods, and abnormal data has been filtered out in order to increase the accuracy of the estimated parameters. The validity and accuracy of the proposed method has been verified by both the simulation and field measurement data.