Simulation of the effect of temperature on space charge transport in LDPE under DC electric field stress

Abstract

Polymers are considered essential materials used in high-voltage direct current (HVDC) applications due to their excellent insulating properties. They are widely employed in various electrical equipment such as cables, transformers, and station insulators, providing effective protection against high currents and voltages. One of the main challenges in these applications is the effect of temperature on the performance of these insulators, as elevated temperatures can alter the electrical properties of polymers, potentially impacting the dynamics of electric charges within the material. In this work, bipolar charge transport (BCT) was used to study the effect of temperature on the dynamics of space charge in LDPE under a DC electric field. The model includes processes such as injection, migration, trapping, detrapping, and recombination. We applied a DC electric field of 50 kV/mm to low-density polyethylene (LDPE) films for 2 hours under different temperatures. The results indicate that higher temperatures significantly enhance charge mobility, leading to improved charge flux, reduced trapping, and increased detrapping of charges. This results in a more uniform distribution of the electric field within the material and a quicker transition to a steady-state condition. The increase in temperature within the applied electric field created a relative balance between trapped charge and mobile charge, indicating a positive effect of higher temperatures on the electrical insulation properties of LDPE.