Practical Application of ±250‐kV DC‐XLPE Cable for Hokkaido–Honshu HVDC Link

SUMMARY The long-term dc properties of DC-XLPE insulation materials, which have been developed for dc use, were investigated. It was found that the lifetime of DC-XLPE under dc voltage application is extended by the addition of nano-sized filler. The time dependence of the space charge distribution at 50 kV/mm was observed for 7 days. Almost no accumulation of space charge in DC-XLPE was found. The 250-kV DC-XLPE cables and accessories were manufactured and subjected to a type test and PQ test for use in the Hokkaido–Honshu dc link facility owned by the Electric Power Development Co., Ltd. These tests were performed under conditions that included a polarity reversal test for line commutated converter (LCC) systems as recommended in CIGRE TB 219. The test temperature was 90 °C. The type test and PQ test were successfully completed. The DC-XLPE cable and accessories were installed in summer 2012 for the Hokkaido–Honshu dc link. After the installation of the dc extruded cable system, a dc high-voltage test at 362.5 kV (=1.45 PU) for 15 min was successfully completed in accordance with CIGRE TB 219. This dc extruded cable system was put into operation in December 2012 as the world's highest-voltage extruded dc cable in service and the world's first dc extruded cable for a LCC system including polarity reversal operation.