Condition Evaluation Method of Cable Based on the Growth of Electrical Tree

Abstract

The diagnosis of XLPE cable lines by partial discharge (PD) has always been a key technical issue. As an important parameter reflecting the insulation status of XLPE cable equipment, partial discharge is closely related to its insulation status. A state evaluation method of cable based on the growth of electrical tree is proposed in this paper, which can realize the quantitative evaluation of cable state. Based on the energy conservation law of electrical tree growth in molecular thermodynamics, the relationship between local discharge signal and electrical tree length in cable insulation is studied. In order to evaluate the insulation condition of a cable element, the partial discharge failure probability of the cable element is solved by using the electrical tree length index according to the stress-strength interference theory in the field of mechanical reliability. In addition, a partial discharge test of 10kV XLPE cable is performed. The data on partial discharge and the growth process of the electrical tree are recorded. By substituting the proposed model for calculating the probability of cable partial discharge faults, the effectiveness of the proposed method in evaluating cable status is verified.