Electric Field Disturbance Near Water Trees In XLPE Insulation of Power Cables and Self-carrying Insulated Wires at Non-Sinusoidal Voltages and Currents

Abstract

The features of electric field disturbance in cross-linked polyethylene (XLPE) insulation of power cables and self-carrying insulated wires (SIW) is studied, taking into account water microinclusions and microtrees that appear in such insulation during manufacture and operation. It is substantiated that the appearance of non-sinusoidal voltages and currents in power transmission lines using power cables and SIW with solid XLPE insulation causes an increase in electro-physical factors aimed at increasing the pulsating electromechanical pressure on the surface of solid XLPE insulation by liquid conductive microinclusions and tree branches and an increase in over time, their sizes along the strength of the existing electric field (EF). The paper defines the patterns of change over time in the magnitude of the electric field stress, stressed volume and the maximum pressure in the XLPE insulation and the additional impact on such patterns of higher harmonic components of electrical voltages and currents during non-sinusoidal processes in such insulation. It is indicated that such electro-physical effects on polymer insulation lead to an increase in the intensity of both threshold mechanisms and stochastic ones of destruction of the insulation microstructure. Thereby it is required the development of additional regulations for standard conditions for manufacture and operation of the XLPE power cables and self-carrying insulated wires.