Title page for ETD etd-12062002-152858


Type of Document Master's Thesis
Author Tsai, Shu-Jen Steven
Author's Email Address stsai@vt.edu
URN etd-12062002-152858
Title Power Transformer Partial Discharge (PD) Acoustic Signal Detection using Fiber Sensors and Wavelet Analysis, Modeling, and Simulation
Degree Master of Science
Department Electrical and Computer Engineering
Advisory Committee
Advisor Name Title
Liu, Yilu Committee Chair
de Wolf, David A. Committee Member
Phadke, Arun G. Committee Member
Keywords
  • Acoustic Emission
  • Fiber Optic Sensor
  • Power Transformer
  • Partial Discharge (PD)
  • Wavelet Transform Denoising
Date of Defense 2002-12-06
Availability unrestricted
Abstract
In this work, we first analyze the behavior of the acoustic wave from the theoretical point of view using a simplified 1-dimensional model. The model was developed based on the conservation of mass, the conservation of momentum, and the state equation; in addition, the fluid medium obeys Stokes assumption and it is homogeneous, adiabatic and isentropic. Experiment and simulation results show consistency to theoretical calculation.

The second part of this thesis focuses on the PD signal analysis from an on-site PD measurement of the in-house design fiber optic sensors (by Virginia Tech, Center for Photonics Technology). Several commercial piezoelectric transducers (PZTs) were also used to compare the measurement results. The signal analysis employs the application of wavelet-based denoising technique to remove the noises, which mainly came from vibration, EMI, and light sources, embedded in the PD signal. The denoising technique includes the discrete wavelet transform (DWT) decomposition, thresh-holding of wavelet coefficients, and signal recovery by inverse discrete wavelet transform. Several approaches were compared to determine the optimal mother wavelet. The threshold limits are selected to remove the maximum Gaussian noises for each level of wavelet coefficients. The results indicate that this method could extract the PD spike from the noisy measurement effectively. The frequency of the PD pulse is also analyzed; it is shown that the frequencies lie in the range of 70 kHz to 250 kHz. In addition, with the assumed acoustic wave propagation delay between PD source and sensors, it was found that all PD activities occur in the first and third quadrant in reference to the applied sinusoidal transformer voltage.

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 28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access 
  Appendixes.pdf 837.20 Kb 00:03:52 00:01:59 00:01:44 00:00:52 00:00:04
  Bibliography.pdf 78.39 Kb 00:00:21 00:00:11 00:00:09 00:00:04 < 00:00:01
  Chapter1.pdf 88.91 Kb 00:00:24 00:00:12 00:00:11 00:00:05 < 00:00:01
  Chapter2.pdf 389.21 Kb 00:01:48 00:00:55 00:00:48 00:00:24 00:00:02
  Chapter3.pdf 333.61 Kb 00:01:32 00:00:47 00:00:41 00:00:20 00:00:01
  Chapter4.pdf 188.13 Kb 00:00:52 00:00:26 00:00:23 00:00:11 00:00:01
  Chapter5.pdf 631.38 Kb 00:02:55 00:01:30 00:01:18 00:00:39 00:00:03
  Chapter6.pdf 88.26 Kb 00:00:24 00:00:12 00:00:11 00:00:05 < 00:00:01
  Front.pdf 146.93 Kb 00:00:40 00:00:20 00:00:18 00:00:09 < 00:00:01
  Vita.pdf 125.95 Kb 00:00:34 00:00:17 00:00:15 00:00:07 < 00:00:01

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