抄録
Long term DC properties of DC-XLPE insulation material, which have been developed for DC use, were investigated. It was found that the life time of DC-XLPE under DC voltage application becomes longer by addition of nano-sized filler. The time dependence of space charge distribution at 50kV/mm was observed for 7 days. As a result, there is almost no accumulation of space charge in DC-XLPE. The 250kV DC-XLPE cables and accessories were manufactured and subjected to a type test and PQ test for the use in the Hokkaido-Honshu DC link facility owned by the Electric Power Development Co., Ltd. These tests were done under the conditions that include a polarity reversal test for line commutated converter (LCC) systems as recommended in CIGRE TB 219. The test temperature was set at 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 362.5kV (=1.45PU) for 15 minutes 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.
