GK Dürnrohr

GK Dürnrohr stands west of Dürnrohr substation in Lower Austria. It was a high-voltage direct current back-to-back station built to exchange power between Austria and Czechoslovakia. The plant operated from 1983 to 1996 with a nominal rating of 550 MW and DC voltage of 145 kV. Transmission losses were only 1.4 per cent. Planning began in 1975 after an agreement between Austria and Poland. Construction started at the end of 1980 and the station went into service in mid-1983. The station’s static inverter used 1056 thyristors, each with a wafer diameter of 100 mm. These were the largest thyristors in the world at the time. The inverter was housed in a reinforced concrete valve hall 29.8 metres long and 13.8 metres high. Two three-phase transformers rated 335 MVA stood on either side of the hall. A smoothing coil with an 85 mH iron core was installed at the eastern end. Four AC filters on both sides kept harmonics under control. Visitors find the valve hall still standing, now used for operational purposes by Verbund AG. Inside, three thyristor towers contain the inverter’s twelve-pulse branches. The cellar holds air conditioning, water cooling and treatment plant. Equipment rooms contain battery and rectifier units, storage and test gear. Outside, a 102-kilometre 380 kV power line runs to Slavětice in the Czech Republic. The line crosses the border near Kleinhaugsdorf and once carried Robert Ospald to freedom in 1986.