Modelling the ion behaviour in polyethylene containing by-products and submitted to high DC field stress

Abstract High voltage direct current links increasingly use polyethylene (PE) based materials as insulation, due to their outstanding electrical and thermal properties. However, it is known for long that ions, present in the crosslinked PE material, play a major role in the space charge behaviour, and hence in the ageing of the material. Crosslinking by-products seem to be related to the activity of ionic processes. However, it is a real challenge to identify the kind of ions and to determine its amount. In this context, simulation tools related to charge transport are of interest to apprehend the impact of the presence of ions, their transport and accumulation, on the overall macroscopic behaviour. The goal of the present paper is to propose a new model related to ion generation and transport, either accounting for dissociation of molecules or to their ionization. The simulations results, consisting in space charge density profiles and currents, are compared to experimental observations available in the literature to conclude on the possible mechanism of ion generation in PE materials containing by-products.