The XLPO cable insulation with synchronous-enhanced DC electrical and high-temperature mechanical properties

High voltage direct-current (HVDC) cable is key equipment for utilizing offshore wind power. The high-temperature mechanical and DC electrical properties are two key figures for crosslinked polyethylene cable insulation, which are always contradictory and difficult to satisfy synchronously. To address the problem, we proposed crosslinked polyolefin (XLPO) insulation with 20.3% enhanced high-temperature mechanical stability and improved DC breakdown strength and volume resistivity. The thermally stimulated current results of XLPO showed depolarization current peaks at higher temperatures, responding to better inhibition of space charge and improved DC insulation. In addition, the XLPO exhibited thermodynamic compatibility with only one endothermic peak in differential scanning calorimetry thermograms and decreased small-angle X-ray scattering long-period. The strategy proposed in this work to enhance the comprehensive performance of cable insulation provides a promising route to next-generation HVDC cables.