The Baltic-Cable is a HVDC power line running beneath the Baltic Sea that interconnects the electric power grids of Germany and Sweden.

The Baltic Cable uses a transmission voltage of 450kV - the highest operating voltage of all facilities for energy transmission in Germany. At 250 kilometres long it is the longest high voltage cable on earth. It is a monopolar HVDC system with a maximum transmission facility of 600 Megawatts.

The course of the Baltic Cable starts at the inverter station at Luebeck-Herrenwyk, which is situated on the site of a former coal-fired power station. It crosses the river Trave in a channel 6 metres below the bottom of the river and then follows its course as sea-cable laid at the Eastern side of this river. After crossing the peninsula at Priwall the cable runs at first parallel to the coast of Mecklenburg-Vorpommerm , in order to turn behind Rostock north-easterly toward Sweden.

From the point on the Southern coast of Sweden where it reaches the land, the Baltic Cable runs for a further 5 kilometres as an underground cable. The last 12 kilometres of the 262 kilometre long Baltic Cable power line are built as overhead lines hung on 40 pylons.

Although Baltic-Cable is a monopolar line, which would only require one conductor on the pylons, two conductors were installed along the whole overhead section. These conductors are permanently connected in parallel in the inverter station at Kruseborg and at the termination of the overhead line.

Because this overhead line can generate radio interferences, there is a highly effective active filter system installed at the Kruseborg inverter station. In the Luebeck-Herrenwyk inverter station, there is no requirement for such a system, because there is no overhead powerline section on the German side of the Baltic Sea.

The cable cannot be operated at the maximum transmision rating of 600 Megawatts, because the 380kV-line which begins at the converter station of Luebeck-Herrenwyk ends at the Luebeck-Siems substation. From there power flows on 220kV and 110kV lines, which reduces the maximum transmission rate and increases the losses of the transmission.

Of the two originally planned 380kV-lines to Luebeck (from Kruemmel Nuclear Power Station to Luebeck-Siems and from Schwerin substation to Luebeck-Herrenwyk), the 380kV-line between Kruemmel and Luebeck-Siems was cancelled according to speakers from the E.ON AG .

There is still the option to build a 380kV-line from Luebeck to another 380kV-substation in Schleswig-Holstein, Hamburg or Niedersachsen. The construction of the 380kV-link between Luebeck-Herrenwyk and Schwerin is not progressing due to opposition from ecologists.

A transmission rate of 600 megawatts should be possible via a new 220kv cable and a SVC (static var compensator) in Lübeck-Siems after 2005.

External links

• Technical information
• Circuit diagrams and track of cable