| 摘要 |
PROBLEM TO BE SOLVED: To easily specify the causes of a fault by analyzing the short-time signal of a transition phenomenon part immediately after a ground fault of a high-voltage power distribution line and hence obtaining characteristics for each cause. SOLUTION: A time frequency analysis result for each cause in a ground fault is accumulated (S1), and a zero-phase current waveform/zero-phase voltage waveform in the ground fault is analyzed (S2). Then, the transition part of the zero-phase current waveform/zero-phase voltage waveform for several ms immediately before the ground fault is detected (S3), and a mother waveletΨ(x) is calculated (S4). Further, the value of the conversion of the wavelet is calculated (S5), and the ratio of each frequency for a fundamental wave is calculated (S6). Then, the time frequency analysis of the transition part is displayed by a topographic plot (S7), comparison is made with the topographic plate for each grounding fault cause by pattern recognition in a step S8, a judgment value is calculated, and this procedure is repeated for increasing the number of learning times.
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