Evaluation of modified XLPE for 320 kV HVDC Cable use at elevated Conductor Temperatures

While cross-linked polyethylene (XLPE) is the industry standard for AC systems, it must demonstrate uncompromising electrical and thermomechanical stability under sustained DC stress and elevated temperatures. A primary objective for reliable HVDC operation remains the optimization of volume resistivity and the mitigation of space charge accumulation [1].

This research details the engineering and rigorous authentication of a DC-optimized XLPE material. Initially, the base resin was refined by integrating ethylene-based polymer blending strategies, building upon preliminary investigations into microstructure and charge transport behaviour [1]. This was followed by a strategic optimization of the crosslinking system, comparing three distinct agent combinations. Among these, a specific formulation exhibited a superior performance equilibrium and was subsequently applied to a full-scale ±320 kV VSC

HVDC cable. The prototype successfully cleared a comprehensive type test (TT) per CIGRE standards. Furthermore, predictive modelling via COMSOL Multiphysics suggests that this material provides sufficient margins for ±525 kV applications, specifically when operated at 70°C with a 28mm insulation layer. These findings underscore the material's readiness for upcoming pre-qualification (PQ) trials and higher-voltage deployments.