Dissertation > Excellent graduate degree dissertation topics show

Study on Fault Line Selection in Non-solid Earth Network Based on the Wavelet Packet Transform

Author: PanMeng
Tutor: LiangJun
School: Shandong University
Course: Proceedings of the
Keywords: Small current grounding system Arc suppression coil Wavelet transform Modulus maxima of wavelet packet MATLAB
CLC: TM862
Type: Master's thesis
Year: 2008
Downloads: 393
Quote: 4
Read: Download Dissertation

Abstract

China's distribution network neutral point of widespread adoption of the small current grounding (including grounding, arc suppression coil grounding and the high resistance grounded) way to avoid the line of single phase grounding fault (also known as the small current grounding fault) caused by tripping The power supply is interrupted. For small current grounding fault, the fault current is weak, unstable arc and random factors and other reasons, ground fault line selection more difficult, has been the lack of reliable fault line selection method and the high accuracy of the small current grounding fault line selection device, serious hinder the improvement of the power supply distribution network reliability and automation level. With the reliability and power quality requirements increase, the small current grounding system fault lines in the single-phase ground fault occurs choice and more attention. Therefore, the study of high accuracy, high reliability, automatic line selection and development of the automatic line selection device, improve power supply reliability, reduce power loss and improve the level of distribution automation is of great significance. For fault line selection in small current grounding system on the basis of the understanding of domestic and international distribution network fault line selection research, analysis of the principle and the advantages and disadvantages of the existing fault line selection method, and analyzed in neutral point grounding system and the neutral point arc suppression coil grounding system steady-state and transient characteristics of single-phase ground fault occurs, especially for the use of fault transient characteristics and transient in-depth study. Fault transient signal is mixed with a singularity of non-stationary noise high-frequency signal. Emerging wavelet theory in the analysis of transient non-stationary signal is superior to the traditional Fourier analysis method, and therefore have good localization characteristic in the time-frequency domain due to its singular point detection commonly used in this type of signal. Wavelet analysis, the choice of the wavelet function is very important, different wavelet function has a different scope and applications; same time, the different scales of the wavelet transform corresponding to the different frequency bands of the signal. In this paper, based on the characteristics of the fault transient signal, summed up the principle of selection of the wavelet function and scale, and at the same time to make a clear definition in the selection of B-spline function and wavelet function summarizes the derivation of the equivalent filter bank . Based on in-depth study of wavelet theory and analysis of small current grounding system single-phase ground fault transient characteristics, this paper proposes the use of a modulus maxima of wavelet packet small current grounding line selection . The line selection method can take full advantage of the small current grounding system effective component in the high-frequency transient zero sequence current of single-phase ground fault line and wavelet space, has a strong anti-interference ability. In this paper, MATLAB software to build a small current grounding system simulation model, a large number of small current grounding system simulation. In the simulation experiment, by docking Location location, close angle, set different parameters such as grounding resistance value of the new method of fault line selection line selection effect analysis, results show that the line selection method is effective and accurate reliability.

Related Dissertations

CLC: > Industrial Technology > Electrotechnical > High Voltage Engineering > Overvoltage and Its Protection > Over-voltage protection devices
© 2012 www.DissertationTopic.Net Mobile