Study on the Morphology and Propagation of Electrical Treeing by Partial Discharge Patterns in XLPE Power Cables

A cross-linked polyethylene (XLPE) power cable sample and an 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 15 kV XLPE power cables were carried out at power frequency of voltages between 12 kV and 21 kV, and different morphologies of electrical trees were analyzed. In addition, partial discharge (PD) patterns of the common statistical characteristic and the time-frequency analysis (TFA) method for the electrical trees with different morphologies and different propagation stages were proposed. Results showed that in an actual XLPE power cable, the degree of skewness (sk) of the maximal and the mean discharging-phase distributions of PD decreases with the propagation of electrical trees, which may be considered as a parameter to diagnose electrical tree propagation stages. The phase-frequency-discharge magnitude (phi-f-q) map from the TFA method can distinguish the PD of electrical trees and the interference signal, and is also related to the morphology and propagation of electrical trees. Copyright (C) 2012 Praise Worthy Prize S.r.l. - All rights reserved.