Analyzing the growth of XLPE insulation damage under the application of repeated lightning impulses using nonlinear models

Abstract

The most commonly used insulation systems in submarine cables and substations nowadays are cross-linked polyethylene(XLPE). The expected life of this insulation is reduced due to the phenomenon called treeing. The reduction in life of the insulation is mainly due to the overvoltage stresses such as lightning strokes affecting the insulation. The growth characteristics of trees under repeated lightning impulses are investigated using nonlinear models in this paper. After solving Poisson’s equations for the required geometry of the XLPE insulation in COMSOL multiphysics, the electric field values obtained are utilized to model the growth characteristics. Repeated lightning impulses are applied as the input to the model. The growth of the tree in the insulation is analyzed by developing a program based on a probabilistic approach. The analysis of the key parameters of insulation damage is assessed by histogram plots.