A method for assessing customer harmonic emission level based on improved fluctuation method

Abstract

raditional fluctuation method estimates the utility harmonic impendence by the ratio of the harmonic fluctuation of voltage to current at PCC, in which fluctuation samples are selected to improve average accuracy. However, the fluctuation filtering method may not increase estimation accuracy of individual sample. This paper proposes an improved fluctuation method based on the phase angle correcting principle. First, the phase angle value estimated by harmonic fluctuation ration of voltage to current is modified. Then, an extension line pointing the actual value of utility harmonic impedance is drawn from estimated dot by use of the corrected phase. The intersection of different extension lines is calculated to approach the actual value. Simulation shows that the improved method in this paper provides a more precise estimation than that provided by traditional fluctuation method in the case that the customer fluctuation is dominant. This method provides an effective way for the estimation of customer harmonic emission level.

Harmonic contribution assessment on the condition of background harmonic fluctuations

“…The filtering principle in statistics is used to determine the customer dominant harmonic current fluctuation and then the background harmonic impedance is estimated [1].…”

“…In the researches, two classes of methods have been proposed to quantify the harmonic contributions of loads: fluctuation quantity based methods [1,2] and linear regression based methods [3][4][5][6]. All these approaches are mainly on the assumption of constant background harmonics, while the background harmonic is time-varying in the practical power systems, hence the approaches cannot be used in the actual systems.…”

“…Linear regression based methods [5,6] are only applied when the harmonic fluctuates slightly in both customer side and utility side, while conventional fluctuation quantity based methods [2] are mostly valid if the harmonic just fluctuates in customer side. On the condition that the harmonic fluctuates strongly in both customer side and utility side, dominant fluctuation filtering method [1] performs well for enough consideration of background harmonic fluctuations. In the paper, the harmonic contributions are assessed on the basis of adopting dominant fluctuation filtering method to determine the background harmonic impedance.…”

A Harmonic Impedance Identification Method of Traction Network Based on Data Evolution Mechanism

“…Moreover, some identification methods of harmonic impedance are widely used in the utility power grid (UPG). Fluctuation methods [14,15] can identify the harmonic impedance through the ratio of the increments of harmonic voltage to current at a point of common coupling (PCC) with high measurement accuracy. Reference [16][17][18][19] proposed linear regression methods.…”

A Piecewise Bound Constrained Optimization for Harmonic Responsibilities Assessment under Utility Harmonic Impedance Changes

“…These works can be mainly classified as fluctuation quantity methods [10,11], linear regression methods [12][13][14] and independent component analysis (ICA) [15,16] methods. Fluctuation quantity methods rely on the fluctuation quantity proportion of harmonic voltage to current for calculating the harmonic impedance.…”