The analysis of damped characteristics and location error of cable oscillation wave testing system

Compared with the traditional detection methods for linked polyethylene (XLPE) cable's partial discharge (PD), the PD detection method based on damped oscillation wave testing system (OWTS) is a new type nondestructive testing technique, which has higher convenience and validity. However, in engineering applications, the effective implementation of the test was greatly hindered by the invalid charge-discharge in the high voltage circuit of OWTS and the location error of PD. With using theoretical derivation method to analyze the principle of PD detection based on damped OWTS, the invalid mechanism for charge-discharge and the error sources of the detection system are clarified. In addition, by adopting time domain reflectometry (TDR) method to calibrate the cable length and wave velocity, the process is coupled with each other. It is very important to obtain accurate cable length and wave velocity, which can make a decisive role in realizing the pre-location of cable's PD defects based on damped OWTS. Meanwhile, by taking an operating 35-kV cable as the test case, the analysis of PD detection in the cables based on OWTS is carried out. As a result, the conclusions of the analysis are of great instructive significance to the detection and location of the cable's PD based on damped OWTS.