Electric field tailoring in HVDC cable joints utilizing electro-thermal simulation: effect of field grading materials

In this study, electric field distribution of cable joints under steady state voltage and transient conditions, i.e. lightning impulse and polarity reversal, was investigated using electrothermal simulation. Field grading techniques including geometric grading and geometric grading with field grading materials were considered as the methods to tailor local electric field distribution based on an electro-thermal model of 80kV joint in COMSOL Multiphysics. The results show 6.5 kV/mm and 6.9 kV/mm decrease in amplitude of electric field at the critical point of the interface in presence of FGM under steady state and polarity reversal transient condition, respectively.