A Finite Element Method Based Approach for Modeling of Partial Discharges in HVDC Cables

Occurrence of partial discharges (PD) is a critical phenomenon preceding an impending insulation failure in HVDC cables. Modeling of PD due to deformations in the insulation is a vital step towards the development of a reliable monitoring tool to assess the condition of cable insulation. Finite Element Method (FEM) is proved to be a constructive technique in modeling partial discharge phenomena in AC cables. Modeling of PD requires the estimation of electric field which is complex in HVDC cables compared to HVAC cables due to the dependence of material conductivity on temperature and electric field inside the cable geometry. This paper is an attempt towards the development of a FEM based model for simulation of partial discharge occurrence due to voids in the insulation of HVDC cables. A three dimensional FEM model of a 500 kV HVDC cable with a cylindrical void inside the insulation is modeled in ANSYS platform. The developed model is simulated for voids of two different sizes and apparent charge is estimated for each case. The simulation results show the feasibility of the developed FEM model to simulate the PD phenomena in HVDC cables under steady DC conditions and changing temperature environment.