Detection Changes in Line Insulation Conductivity by High-Frequency Voltage and Current Pulsations Using Wavelet Transform

The cable line is one of the main elements in the power transmission system, but due to the cable lines considerable length, monitoring the line condition and tracking its damage is a complex process. In practice, methods quite a variety are used to monitor the line condition, through monitoring the change in current and voltage in high-voltage cable lines with long distances, and control parameters using equivalent circuits.Study object is a short cable line, 6 km long, with a connected source of 6 kV, in a network with a non-linear load. Given its short-length, the overall changes in voltage and current will not have significant deviations between the input and output of the cable line. The main observation is carried out in the high frequencies area at a 2500 Hz frequency with the expectation of evident deviations in the current and voltage caused by the influence a non-linear load.By conducting two experiments, a line without damage and a line with damaged insulation, a number of deviations in the pulses change over time were revealed. The most evident deviations occur in the current, which is expressed due to a change in the main pulses amplitude and the significant appearance low-amplitude fluctuations between damaged phases under the influence of opposite-phase pulses.