High-frequency Signal Acquisition And Data Analysis Based On Virtual Instrument

After the cable failure occurred, troubleshooting timely and restoring power efficiently can avoid significant economic losses caused by power blackouts. Traditional ways on cable fault detection can only solve a part of the problems and the results may not ideal. So, this paper introduced a portable and rapid method by building a virtual instrument in Labview environment to realize the combination of wavelet thresholding method and three pulses measurement. And it also present a low-voltage pulse generator that can perform well under the measurement standards.First of all, as the fault waveforms can be easily interfered, a method that using wavelet thresholding to process the waveforms in this paper was proposed.At the same time, considering the coupling relationship between threshold and threshold functions, to achieve the optimal result by selecting threshold and threshold function, an algorithm was proposed that can achieve bidirectional optimization within the range from zero to a high-frequency cut-off threshold. According to the corresponding relationship between optimal threshold and changes of decomposition level, the selection of decomposition level can be realized by selecting optimal threshold.After choosing clock and optocoupler belong low-voltage DC pulse generator and finishing the design of pulse generating circuit, peak measurement circuit and over-voltage protection circuit under measurement standards, the simulation test shows that generator is qualified.To verify the feasibility and accuracy of the proposed fault location method, different short and open cable faults have been emulated in Simulink. The virtual instrument on cable fault detection is also constructed in Labview. It almost achieved the fuctions that acquisition, storage, playback, filtering, correlating of pulse waveform. According to measurements of 100 m, 75 m, 50 m wires, paper pointed out the instrument’s lacks and improving directions.