Online estimation of thévenin equivalent using discrete fourier transform

Abstract

This paper presents a method for the determination of the Thévenin equivalent (TE) parameters of a power system using local phasor measurement unit (PMU) measurements. The proposed method is based on an innovative use of Discrete Fourier Transform (DFT), where the DFT coefficients are calculated for the measured voltage and current phasors, which are used to determine the TE parameters. The method presented exploits the characteristics of DFT to develop a new simple and efficient method for TE determination. The calculated DFT is also utilized to detect the presence of measurement errors and to get the best estimate of TE parameters in such conditions and also enable identification of the erroneous measurement. The proposed method is illustrated using a simple system and tested with the data of standard test systems, which all verified the accuracy of the proposed method.