科技進步促使傳統工業轉型成高科技產業，供電品質與電力品質更顯重要，因此，本論文主旨即在於應用改良型時頻轉換之方法，並針對電力品質之訊號，予以深入分析探討。
本文首先應用Gabor-Wigner轉換探討高阻抗接地故障。Gabor-Wigner轉換除了適用於非穩態訊號之外，其主要優點為時頻解析度高，並可克服Wigner分佈所衍生之雜訊問題。本文所提方法已應用於水泥地之高阻抗接地故障、濕土地之高阻抗接地故障以及草地上之高阻抗接地故障等不同情況下之接地故障偵測。由本文實驗結果顯示此方法可正確偵測出各種不同狀況之高阻抗接地故障，確有助於故障偵測分析領域之提昇參考。
其次，本文將所提出的方法探討於各種不同之電壓閃爍訊號，其中包括5 Hz電壓閃爍頻率、10 Hz電壓閃爍頻率、電壓閃爍訊號加入諧波之訊號以及電弧爐運轉之電壓閃爍訊號等。由模擬產生之波形及實地實測之波形測試結果顯示，本文所提之方法均可有效偵測各種環境時之電壓閃爍變動情形，有助於提供相關電力工程人員掌握電力運轉品質之相關資訊。
再者，本文將所提出的方法探討間諧波訊號，而由模擬分析及訊號實測顯示，本文方法可偵測出間諧波之發生時間點、頻率及各頻率之振幅。而且在分析各量測訊號時，均能精確掌握，並無誤判情形發生。
最後，本文將所提出的方法進行探討電壓驟降及電壓中斷之訊號，實驗結果佐以說明本文方法不僅可有效分析電壓驟降及電壓中斷之時間點、頻率及振幅，而且時頻解析度較佳，研究成果有助於目前電力品質之研究改進參考。

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.

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