Electric Field Distribution in HVDC Cable Joint in Non-Stationary Conditions

Thi Thu Nga Vu, Gilbert Teyssedre and Séverine Le Roy
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Thi Thu Nga Vu: Faculty of Electrical Engineering, Electric Power University, 235 Hoang Quoc Viet, Hanoi 10000, Vietnam
Gilbert Teyssedre: Laboratory on Plasma and Conversion of Energy, University of Toulouse and CNRS, 118 Route de Narbonne, 31062 Toulouse, France
Séverine Le Roy: Laboratory on Plasma and Conversion of Energy, University of Toulouse and CNRS, 118 Route de Narbonne, 31062 Toulouse, France

Energies, 2021, vol. 14, issue 17, 1-17

Abstract: Accessories such as joints and terminations represent weak points in HVDC cable systems. The DC field distribution is intimately dependent on the thermal conditions of the accessory and on material properties. Moreover, there is no available method to probe charge distribution in these conditions. In this work, the field distribution in non-stationary conditions, both thermally and electrically, is computed considering crosslinked polyethylene (XLPE) as cable insulation and different insulating materials (silicone, rubber, XLPE) for a 200 kV joint assembled in a same geometry. In the conditions used, i.e., temperatures up to 70 °C, and with the material properties considered, the dielectric time constant appears of the same order or longer than the thermal one and is of several hours. This indicates that both physical phenomena need to be considered for modelling the electric field distribution. Both the radial and the tangential field distributions are analysed, and focus is given on the field distribution under the stress cone on the ground side and near the central deflector on the high voltage side of the joint. We show that the position of the maximum field varies in time in a way that is not easy to anticipate. Under the cone, the smallest tangential field is obtained with the joint insulating material having the highest electrical conductivity. This results from a shift of the field towards the cable insulation in which the geometrical features produce a weaker axial component of the field. At the level of the central deflector, it is clear that the tangential field is higher when the mismatch between the conductivity of the two insulations is larger. In addition, the field grows as a function of time under stress. This work shows the need of precise data on materials conductivity and the need of probing field distribution in 3D.

Keywords: HVDC cable system; accessories; space charge; field distribution (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (4)

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