Predicting the electric field distribution in polymers used as electrical insulating materials remains the Holy grail, as the presence of charges disturbs the Laplacian electric field. Charges arising from the electrodes are one of the dominant mechanism of charge generation, particularly in polyethylene-based materials. Hence, nanometric scale processes at play at the interface have a non negligible impact on charge injection. In the present study, a bipolar charge transport model developed in 2D is used to simulate the impact of several nanometric scale processes, such as the variation of the barrier height linked to the chemical structure of the material at the interface, as well as surface roughness. Simulation results as regards net charge density, current, but also recombination rate, will be compared to a case where no specific supplementary hypothesis is set at the electrodes. At last, simulations have been performed for a combination of roughness and barrier height variation along the electrode.