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

Abstract

Utility harmonic impedance is an important parameter for harmonic mitigation. In this paper, a method for utility harmonic impedance estimation method based on constrained independent component analysis is proposed. The conventional impedance estimation method based on ComplexICA has two major problems: the algorithm is not suitable for separating weak and strong source mixed signals, and lots of sample data should be provided to avoid converging on a local optimum. To solve the two problems, the prior information of the utility harmonic source is added to the objective function of ComplexICA; in this paper, the measurement data at PCC when the load is shutdown are chosen as the prior information. Then the utility harmonic source signal can be recovered and the separated matrix can be obtained effectively. The connection between the utility harmonic source, utility harmonic impedance and the data at PCC are established using Norton equivalent circuit, and then the separation matrix is used to calculate utility harmonic impedance. The performance and feasibility of the proposed method are verified by the computer simulation and field test. Compared with the current ComplexICA method, the proposed method is more adaptive to changes in the background harmonic and the calculation result is more stable.

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

“…If some prior information of the impedance matrix or harmonic sources can be found, the estimation accuracy will increase. In some paper, the measured harmonic voltages and currents at PCC when the load is shutdown are selected as the prior information of the utility side harmonic sources, 23 which requires the utility harmonic source to keep steady during the whole calculation period. However, the utility harmonic sources are usually composed of the harmonic sources except for the concerned nonlinear loads, so it varies with these harmonic sources.…”

“…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. The method based on covariance characteristics of random vectors, which measures the utility harmonic impedance based on the utility harmonic source and the harmonic current at PCC are weakly correlated or independent, it can suppress the influence of background harmonic to some degree.…”

“…Harmonic load fluctuation is composed of fast-varying components and slow-varying components, and the fastvarying components are independent. 19 Therefore, the independent component analysis methods are proposed [20][21][22][23] based on this principle. These methods are free from the assumption that the customer side harmonic impedance is much large than that of the utility side, which can estimate the harmonic impedance accurately when the background harmonic fluctuates acutely.…”

On Adaptive Control for Electrical Discharge Machining Using Vibroacoustic Emission

“…If not taken into attention to the mass of the wire sections h 1 and h 2 and mass losses on electroerosion wear [49,50], an amplitude of oscillation may be presented as a complex amplitude of the harmonic signal [51][52][53]:…”

Design and Implementation of Novel Multi-Converter-Based Unified Power Quality Conditioner for Low-Voltage High-Current Distribution System

“…With the development of science and technology, the electronic loads have increased largely [2]. A great amount of harmonic loads has been employed in the manufacturing industry, entertainment centers and financial enterprises, which can inject plenty of harmonic currents into the grid [3][4][5]. Furthermore, large numbers of single-phase loads are connected to the distribution system [6].…”