Báo cáo hóa học: Research Article On the Empirical Estimation of Utility Distribution Damping Parameters Using Power Quality Waveform Data

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Báo cáo hóa học: " Research Article On the Empirical Estimation of Utility Distribution Damping Parameters Using Power Quality Waveform Data"Hindawi Publishing CorporationEURASIP Journal on Advances in Signal ProcessingVolume 2007, Article ID 95328, 12 pagesdoi:10.1155/2007/95328Research ArticleOn the Empirical Estimation of Utility Distribution DampingParameters Using Power Quality Waveform Data Kyeon Hur,1 Surya Santoso,1 and Irene Y. H. Gu2 1 Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX 78712, USA 2 Department of Signals and Systems, Chalmers University of Technology, 412 96 Gothenburg, Sweden Received 30 April 2006; Revised 18 December 2006; Accepted 24 December 2006 Recommended by M. Reza Iravani This paper describes an efficient yet accurate methodology for estimating system damping. The proposed technique is based on linear dynamic system theory and the Hilbert damping analysis. The proposed technique requires capacitor switching waveforms only. The detected envelope of the intrinsic transient portion of the voltage waveform after capacitor bank energizing and its decay rate along with the damped resonant frequency are used to quantify effective X/R ratio of a system. Thus, the proposed method provides complete knowledge of system impedance characteristics. The estimated system damping can also be used to evaluate the system vulnerability to various PQ disturbances, particularly resonance phenomena, so that a utility may take preventive measures and improve PQ of the system. Copyright © 2007 Kyeon Hur et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.1. INTRODUCTION Based on this background, it is desirable to predict the likelihood of harmonic resonance using system damping pa-Harmonic resonance in a utility distribution system can oc- rameters such as the Q factor and the damping ratio ζ at thecur when the system natural resonant frequency—formed by resonance frequency. The Q factor is more commonly knownthe overall system inductance and the capacitance of a ca- as the X/R ratio. The reactance and resistance forming the Q factor should be the impedance effective values that includepacitor bank—is excited by relatively small harmonic cur- the effect of loads and feeder lines, in addition to impedancesrents from nonlinear loads [1]. The system voltage and cur-rent may be amplified and highly distorted during the reso- from the equivalent Thevenin source and substation trans-nance encounter. This scenario is more likely to occur when former. In other words, the X/R ratio is influenced by thea capacitor bank is energized in a weak system with little or load level. When the ratio is high, harmonic resonance is more likely to occur. Therefore, this paper proposes an effec-negligible resistive damping. During a resonance, the volt-age drop across the substation transformer and current flow- tive algorithm to estimate the X/R ratio based on linear dy-ing in the capacitor bank is magnified by Q times. Q is the namic system theory and the Hilbert damping analysis. Thequality factor of a resonant circuit and is generally repre- estimation requires only voltage waveforms from the ener-sented by XL /R, where XL and R are the reactance and resis- gization of capacitor banks to determine the overall systemtance of the distribution system Thevenin equivalent source damping. It does not require system data and topology, andand substation transformer at the resonant frequency. Note therefore it is practical to deploy in an actual distribution sys-that during a resonance, the magnitude of XL is equal to but tem environment.opposite in sign to that of XC , the reactance of a capacitor There has been very little research carried out on this subject. Most previous efforts have been exerted on voltagebank. In addition, during a resonance, XL and XC reactancesare h and 1/h multiple of their respective fundamental fre- stability issues in the transmission system level, such as dy-qu ...