Preliminary Experimental Investigation of the Effect of Long Temporary Overvoltages on the Reliability of HVDC Extruded Cables

Pole-to-ground faults in HVDC transmission systems with Voltage Source Converters may cause Long Temporary Over-Voltages on the healthy pole of the configuration. This work aims at a preliminary experimental evaluation of the effect caused by the repetitive application of such Long TOVs on the XLPE insulation for HVDC cables. This paper also studies the changes in the dielectric relaxation properties, with their proposed mechanism, of 0.15 mm-thick XLPE sheets after being subjected to different levels of electrical aging due to TOVs.