Study on propagation characteristics and analysis of partial discharges for electrical treeing in XLPE power cables

XLPE power cable sample and electrode system were designed and built to simulate electrical treeing in actual XLPE cables. Results showed that the testing system can meet research requirements on electrical treeing. Electrical treeing tests on samples of 15kV XLPE power cables were carried out at power frequency of voltages between 12kV and 21kV and the influence of voltage on morphology of electrical trees was analyzed, In addition, partial discharge (PD) patterns of electrical trees during tree growth were also studied. It has been found that propagation of electrical trees can be divided into four stages. The maximal discharging-phase distributions, average discharging-phase distributions and statistical parameters derived from PD distributions were presented. The results showed that in actual XLPE power cable, the effect of voltage si similar to needle-plate electrode system on morphology of electrical trees, however, there are some differences in propagation process of electrical trees, and sk value of the maximal discharging-phase distributions decreases with the propagation of electrical trees, which may potentially be considered as a parameter to diagnose electrical tree propagation stages.