Study of Time Delay of UHF Signal Arrival in Location Partial Discharge

In the study of location partial discharge in transformer based on the UHF method, in order to accurately locate partial discharge source, precisely achieving time delay of different signals which are received by different UHF sensors and radiated from the same partial discharge source is essential. Three methods of time delay estimation are introduced and compared, including the initial peak, the inflection point of cumulative energy curve, cross correlation, and the measures of signal de-noising based on the wavelet transform and cubic splines interpolation are introduced to optimize the methods mentioned above. Then the pin-to-flat electrode model and the wedge model are adopted respectively to experiment these methods. Results demonstrate that absolute error between the time delay estimation through optimized cross correlation and the time delay in theory, which is less than 30 ps, is the least among the errors through other methods mentioned above, and the optimized cross correlation analysis can achieve the highest precision among other methods and can be used to accurately locate partial discharge source.