Localization and Detection of Thermal Defects in High Voltage Cable Insulation Based on Time-Frequency Domain Reflection Method

The overload fluctuation in the operation of high voltage cable will lead to thermal defect aging. The detection of thermal defect aging plays an important role in the safe operation of high voltage cable. In this paper, a time-frequency domain reflection-based thermal defect location detection method for high voltage cable insulation is proposed. Locate thermal defects by injecting high-frequency signals with time-frequency characteristics and utilizing traveling wave reflections due to impedance mismatch. The experimental results show that WVD will appear cross terms, but the localization is more accurate. PWVD can reduce the influence of cross terms, but the localization error is large. Therefore, we can use the PWVD calculation results to eliminate the cross term interference of the WVD calculation results, and then use the WVD calculation results for the localization of the method.