Life Estimation of Extruded HVDC Cables Under Prequalification Test Conditions

The goal of this paper is the evaluation of the loss of life fractions as well as the life of cable for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$500-\text{kV}$</tex> DC cables with XLPE insulation under pre-qualification test load cycles. A previously developed ad-hoc MATLAB code was refined to consider two HVDC cables, the first one has a copper conductor with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2000 ~\text{mm}^{2}$</tex> cross-section, while the second cable has an Aluminum conductor with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2500 ~\text{mm}^{2}$</tex> cross-section. The time-varying temperature and electric field profiles are calculated. Then, the fractions of life lost and the cable life at five radii within the insulation wall are evaluated via the electrothermal life model in the Miner's law framework. A comparison between the field profiles, the life fractions lost, and the life of cable insulation calculated by means of the rigorous and the approximate method for the electric field is carried out.