A New Assessment Method of Customer Harmonic Emission Level

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

“…This can be explained by the fact that subtracting shifted noise realizations ξ r and ξ r À p in Equations (3) or (4) makes the resulting noise Δξ r correlated, as some of the noise samples are repeated within a single data window, even if the original noise ξ was white. This serial correlation raises the variance of the resulting noise realization, that is, var Δξ r ð Þ ¼ var ξ r À ξ r À p ¼ var ξ r ð Þ þ var ξ r À p þ 2cov ξ r ; ξ r À p (16) by the value of 2cov(ξ r , ξ r À p ), which can be significant for low p. Increasing p results in the decrease of the share of repeated noise samples within a window. In this situation, the noise variance var(Δξ r ) decreases, and consequently, the errors of HI estimation decrease.…”

An impedance matrix constrained‐based method for harmonic emission level estimation

“…Typical non-intrusive methods include fluctuation method, 13,14 linear regression method, [15][16][17] random vectors covariance method, 12 Cauchy mixed model-based method, 18 and independent component analysis (ICA) method. [19][20][21][22][23] The fluctuation method and linear regression method are poor in terms of resisting the variation of background harmonic inherently, which usually requires background harmonic source keep constant, and the customer side harmonic source is the dominant harmonic source at PCC.…”

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

“…Many studies have been conducted to determine customers' harmonic contribution; the Norton equivalent circuit is usually adopted, and the key parameter in the equivalent circuit to estimate harmonic contribution is the utility harmonic impedance [4]. Therefore, in recent years, many studies have been focused on the estimation of utility harmonic impedance, which can be divided into invasive methods [5][6][7][8][9][10] and non-invasive methods [11][12][13][14][15][16][17][18][19][20][21][22]. Invasive methods intend to create a disturbance in power system, and then measure the responses of harmonic voltage and current at PCC.…”

“…Several non-invasive methods for utility harmonic impedance estimation have been proposed. For example, in fluctuation methods [11,12], the utility harmonic impedance is quantified using the ratio of harmonic voltage fluctuation and harmonic current fluctuation. The selection of fluctuation data only caused by the customer side is the key to this method, but in practice, utility side and customer side often fluctuate simultaneously.…”