The balanced properties of next generation DC XLPE insulation

The installation of HVDC cables has continuously increased since the implementation of the first commercial HVDC cable link between the Swedish mainland and the island of Gotland during the 1950s. Since the introduction of extruded HVDC materials almost two decades ago, the installation rate of HVDC cables has increased significantly. This has mainly been triggered by the integration of the renewable energy sources in the grid and an increased connectivity between different countries and energy markets. XLPE materials have also gained an increased usage due to their simple manufacturing, laying and jointing procedures with pre-fabricated joints [1]. The HVDC links in service today utilising extruded XLPE materials are commisioned and operating at voltage levels up to 320 kV. The demand from the market has been directed towards increasing the transmission voltages in order to transmit more power over longer distances. This due to that the actual load centres commonly are located far way from the new renewable energy sources such as off-shore wind and hydropower.