Life Estimation of HVDC Cables Subjected to Fast and Slow Polarity Reversals

Abstract

This paper aims at estimating the life of extruded HVDC cable insulation subjected to fast and slow voltage polarity reversals (VPRs). An ad hoc MATLAB code is used for the transient electric field simulation in the cable insulation thickness by solving numerically Gauss, ohm, and current continuity equations beside a macroscopic conductivity equation. A transient temperature is also considered during slow VPR transients. The results show a significant localized reduction in the life of the inner insulation, making the life distribution non-monotonous inside the insulation thickness. The results show that fast VPRs are the most stressing transients in this study. The longer the duration of the zero-voltage period in slow VPR, the less stressed the insulation, hence, the longer the local life in the inner insulation of the cable. The latter is justified by the charge relaxation during slow VPRs.