A Modified Time-Frequency Transform and Its Application to Power Quality Signal Supervision

  • 承 江永

學生論文: Doctoral Thesis

摘要

Continuous technological advancement has enabled conventional industries to upgrade into high-tech industries The emphasis on the quality of supplying power has hence becomes more important than ever Therefore this study thoroughly investigated power supply quality signals by using an improved time-frequency transform method This study first proposed Gabor-Wigner transform to investigate high impedance fault detection In addition to being applicable to non-stationary signals Gabor-Wigner transform exhibited major advantages such as considerably high time-frequency resolution and capability to overcome the noise problem in Wigner distribution The method proposed in this dissertation was applied to high impedance fault detection in various situations including on a cement ground wet ground and lawn The experiment results revealed that this method can correctly detect high impedance faults in various conditions serving as useful references for the study in the field of high impedance fault detection Furthermore the method proposed in this dissertation was applied to investigate various voltage flicker-generated signals such as 5Hz voltage flicker-generated signals 10Hz voltage flicker-generated signals voltage flicker-generated signals with harmonic signals and the voltage flicker-generated signals produced by electric arc furnace operations Test results of waveforms that were generated from simulations and measurements revealed that the proposed method effectively detected voltage flicker variations in all scenarios benefiting engineers to grasp the quality information of power operations The method proposed in this dissertation was also applied to discuss the inter-harmonic signals produced during the simulation and actual experiment When analyzing the inter-harmonic signals in simulation this method correctly detected the frequency and the time point of inter-harmonic signal occurrence and the amplitude of each frequency Moreover when analyzing inter-harmonic signals of actual experiments this method completed with a good detection without committing any misjudgment Finally the method proposed in this dissertation was used to investigate signals of voltage sag and voltage interruption as well The results show that this method can identify the time point frequency and amplitude of power sags and interruptions This method has also exhibited a higher resolution The outcomes gained from these tests are useful for the improvement of electric power quality study
獎項日期2016 三月 25
原文English
監督員Shyh-Jier Huang (Supervisor)

引用此

A Modified Time-Frequency Transform and Its Application to Power Quality Signal Supervision
江永, 承. (Author). 2016 三月 25

學生論文: Doctoral Thesis