Space charge dynamics of epoxy/micro-Al2O3 composites under multi-physical fields

Abstract

The direct current gas insulated transmission line (DC GIL) technique has emerged as a promising solution to achieve carbon neutrality and enable efficient long-distance transmission of renewable energy. However, the stable and long-term operation of DC GIL insulators poses a significant challenge that requires insulating materials capable of overcoming charge accumulation issues against multi-fields, including electric, temperature, and force. Here, we investigate the space charge dynamics and electrical conductivity of epoxy (EP) resin and EP/micro-Al2O3 composites under various stimuli of electrical, thermal, and mechanical stresses, using two modified pulsed electro-acoustic and electrical conductivity measurement systems with mechanical pressure control. It is found that stronger electric fields and higher temperature conditions have a more significant impact on space charge accumulation, while higher mechanical stress results in more shallow traps in EP composites. Furthermore, the bipolar carrier transport modeling and numerical calculations are performed to rationalize the experimental observations and reveal the mechanistic impacts of multi-physical fields on the space charge behavior of EP composites for DC GIL insulator use.