The HVDC Visby-Nas is a bipolar HVDC- plant taken in between Visby and a wind power centre in the proximity of Nas on Gotland, taken in service in 1999. The operating voltage of the HVDC Visby-Nas is 80kV and the maximum transmission rate 50 megawatts. The HVDC Visby-Nas implemented as 70 kilometers long underground cable allows a more stable line operation than an alternating current transmission by its extensive regulation possibilities. Because right of ways for overhead lines require nowadays long during procedures, mentioned line was realized as underground cable. Underground cables for three-phase alternating current are more extensive than those for direct current, which also led to the choice of an HVDC transmission.
