Harmonic impedance estimation in frequency deviation scenario

Abstract

Harmonic impedance is an important parameter for electrical power system analyses. This parameter can be used in some important application such as island and resonance detection. The methods used for impedance estimation can be separated in two categories: Invasive and noninvasive methods. The noninvasive methods do not cause any disturbance in the grid, but the results are less accurate than the invasive methods. However, in both methods, when there is frequency deviation, the results are less accurate, due to the spectral leakage caused by asynchronous sample rate. Then, this work presents a technique to improve the results of the impedance estimation using Lagrange Interpolation to synchronize the sampling and to avoid the spectral leakage.