Including the calculation of transient electric field in the life estimation of HVDC cables subjected to load cycles

A procedure for life estimation of HVDC cables under the time-varying electrothermal stress associated with load cycles was proposed for the first time in [13]. This procedure relies on a few approximations. The most severe is that the DC field EDC(r,t), at radius r within the cable insulation and at time t during the thermal transients associated with load cycles, is calculated using Eoll’s formula for the DC electric field EDC(r) in steady state [14]. This approximation was called the “quasi-steady” DC field hypothesis in [13], since it is equivalent to assuming that the field varies slowly between one steady (or equilibrium) profile to another. The aim of the present paper is to improve the procedure for life estimation of DC cables subjected to load cycles, by replacing the quasi-steady hypothesis with an approach that involves solving Maxwell’s equations in accordance with the guidelines given in [15].