A new method for noninvasive measurement of grid harmonic impedance with data selection

Abstract

Summary The paper presents a new, noninvasive method for the measurement of power grid harmonic impedance. The method is a robust variant of transfer function estimation method. Its novelty lays in the way of selecting local harmonic impedance estimates for averaging, based on input–output coherence estimates, which immunizes it against background voltage variations. The method is validated by simulation including varying background voltage harmonics, both for fixed and slowly varying harmonic impedance. It has also been tested with noisy and nonsynchronously sampled signals. The method is compared with another noninvasive method with data selection. Simulation results clearly show that the proposed method returns lower estimation errors. Also, its computational complexity is significantly reduced compared with the reference one. The presented results of a field test conducted at medium‐voltage/low‐voltage substation prove that the method works well in real conditions. Copyright © 2015 John Wiley & Sons, Ltd.

Harmonic current emission level assessment of residential loads based on impedance-gathering trend

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“…Utility harmonic impedance is a key factor to assess harmonic emission levels in power systems, since it can be used to successfully distinguish the utility‐side and customer‐side harmonic contributions . Calculation methods of utility harmonic impedance can be divided into categories, ie, invasive and noninvasive methods . With invasive methods, utility harmonic impedance is extracted from the variations of voltage and current caused by the injected harmonic current.…”

A Method for Utility Harmonic Impedance Estimation Based on Constrained Complex Independent Component Analysis

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