Modelling charge transport in a HVDC cable using different softwares: from fluid models to macroscopic model

Modelling charge transport in a solid organic insulation has been actively developed this last decade, using homemade models or commercial ones for the case of fluid models, or macroscopic models based on the Maxwell-Wagner theory. Until now, no comparison has been performed to understand the advantages and drawbacks of each type of modelling. Moreover, the availability of 2D or 3D space charge measurements makes it now possible, in theory, to develop the available models in 2D or 3D. Going in this direction, two different fluid models, using either the finite volume method or the finite element method, and simulating charge transport in a model cable have been developed. A third model, macroscopic, based on the variation of the conductivity as a function of the electric field and the temperature has also been developed in parallel. We first compare the simulated results obtained using these models for the case of a polyethylene-insulated cable, i.e. a cylindrical geometry where the electric field and the temperature are not homogeneous along the insulation. The comparison shows the differences between the macroscopic model and the fluids ones, due to the fact that injection and bulk trapping of charges are not treated in the macroscopic model. A special attention is also paid to the comparison between the different fluid models, and to show the difficulty to handle the commercial software.