The invention discloses a
partial discharge ultrahigh-frequency
signal initial time determination method based on a difference energy function. The method comprises the steps of (1) arranging a ultrahigh-frequency sensor on to-be-tested equipment, acquiring and sampling an ultrahigh-frequency
signal waveform generated by the
partial discharge by high-sampling-rate digital
testing equipment; (2) calculating a cumulative energy function of the ultrahigh-frequency
signal waveform generated by the
partial discharge; (3) optimally selecting the length WL of a data window, and calculating the difference energy function of the cumulative energy function from a first data window based on the sliding window
algorithm; (4) determining a moment corresponding to the first significant
peak value of the difference energy function, and adopting the moment corresponding to the first significant
peak value of the difference energy function as an initial moment for ultrahigh-frequency signals. According to the technical scheme of the invention, by the difference energy function, the rapid growth position of the cumulative energy function is strengthened and the
slow growth part of the cumulative energy function is weakened. Meanwhile, the
white noise and the low-frequency and narrow-band
noise in ultrahigh-frequency signals are corresponding to the
slow growth part of the cumulative energy function. Therefore, the level of the
white noise and the level of the narrow-band
white noise are effectively reduced by the difference energy function.