Baltic Cable
The Baltic Cable is a high-voltage direct current transmission line for coupling the German and the Swedish power grid.
The Baltic Cable used with 450 kV, the maximum operating voltage of all systems for transmitting power in Germany and was up to the commissioning of the NorNed in 2008 with a transmission distance of 250 km, the longest in Europe one in use high voltage cable. The transmission line is realized as a high-voltage direct current (HVDC) transmission with a maximum transmission power of 600 MW.
Principle
For a submarine cable, the principle of a monopolar DC transmission is that only one pole is shifted as an isolated cable in the ground or at the sea floor.
The second pole is executed as electrodes in the water. When return is at the sea crossing the sea water and upper soil layers. In order to achieve a low resistance grounding, the grounding device is designed as a large-scale structures, the so-called electrodes. The electrical conductivity of sea water plays due to the large cross-section for the resistor does not matter. In the Baltic Cable the electrodes of the grounding consist of a bare copper ring with a radius of 1000 m.
Environmental aspects of the recessed electrode in the water
In seawater, the current transport through the ion conduction. Triggered by the maximum electric direct current of 1340 A at the electrodes results in electrolysis of the electrodes to a chemical decomposition of the sea water or the dissolved salts. At the anode the water in the dissolved chloride is oxidized to chlorine, to the cathode of the sea water is reduced to hydrogen and hydroxide ions. This 41 kg chlorine at the anode and 47.8 kg of sodium hydroxide at the cathode in the Baltic Sea are released daily. Which of the two electrodes is on Swedish and German side, the anode and cathode, respectively, depends on the current direction: This is from the direction of power flow, depending on whether the electrical power from Germany to Sweden or transported is reversed, and the electrical polarity of the trunk.
By a further increase in the surfaces of the electrodes, the release of chlorine and sodium hydroxide solution can be distributed on a larger quantity of water, and thus the concentration of the reaction products to be reduced by dilution. Although increases with increasing distribution of the reaction products, the affected area of the Baltic Sea, but takes within the affected area from the environmentally toxic effects according to the dilution of the reaction products. Since the electrolysis to maintain the electrical line ( ionic conduction ) is required by the sea water, the electrolysis can be completely avoided by a metallic connection between the two electrodes.
Alternatively, the extension to a bipolar system is possible. After making such an extension would, if both poles are working with equally strong current, no current can flow through the grounding electrodes and therefore no electrolysis of seawater occur. In fact, quite a few monopolar HVDC systems have been extended to bipolar systems (example: Kontiskan ). The overhead line section in Sweden is prepared by the installation of two conductor cables for this and at least on the grounds of the converter station Arrie in Sweden is enough space available for the establishment of a second power converter. Whether it will, in the foreseeable future for this expansion, which could allow a double transmission capacity is questionable because of the suboptimal network connection in Lübeck.
Line course
The Baltic Cable starts in an erected on the site of a former coal-fired power plant in Lübeck- Herrenwyk converter station (53 ° 53 ' 49 "N, 10 ° 48' 9" O53.89694444444410.8025 ). Immediately adjacent to this station is still a 110-kV-/10-kV-Umspannwerk Stadtwerke Lübeck GmbH network, which laid on the masts of Lübeck- Siems 380-kV-/110-kV-Freileitung -Lübeck Herrenwyk two 110 kV three-phase circuits is fed. Pairing from a 380-kV-/110-kV-Transformator on the grounds of the converter station in Lübeck- Herrenwyk not exist.
The light emanating from the converter station "Baltic Cable", which consists of the 450 - kV high-voltage cable and the leads to the electrodes in the Baltic Sea electrode cable crosses under the area lying adjacent to this area Travelodge in a channel 6 feet below the bottom of the Trave, and then then as misplaced in the Travelodge submarine to follow it to its mouth.
After crossing the Priwall Peninsula, the Baltic Cable follows the coast of Mecklenburg- Vorpommern, then east of Rostock slowly to the northeast, to run towards Sweden. The leading to the electrode electrode cable runs to about 5 km north- west of Glasin - Warnkenhagen, Mecklenburg- Vorpommern 54 ° 2 ' 1 "N, 11 ° 3' 11 " O54.033511.053194444444 parallel to high voltage cables ( distance about 1 meter, in the channel under the Travelodge laid next to the high-voltage cables).
At this point it branches off to the east of the route to lead to the electrode at 54 ° 1 ' 42 "N, 11 ° 8' 24 " O54.02833333333311.14. This is designed as a bare copper ring with a radius of 1000 meters off the German Baltic coast Glasin - Warnkenhagen. The 32- kilometer-long electrode cable is a XLPE - insulated copper cables. The first calculated from the converter station in Lübeck- Herrenwyk 20 kilometers of this cable have a cross section of 1400 mm ², the last 12 km of a 800 mm ².
From the landing point on the south coast of Sweden, the 450 - kV cable still leads over a distance of 5.5 kilometers of underground cables to a point east of the E6 at (55 ° 25 ' 28 " N, 13 ° 3' 39" O55.42444444444413.060833333333 ) over land. From there, the overhead line over two suspension towers ( ' " 12 13 ° 3 N, " 50' O55.43055555555613.053333333333 55 ° 25 ) extends to the first Abspannmast in north- northwesterly direction. At this pole, the line changes direction in a north northeast direction and leads east to Södra Haslov past seven masts supporting the next Abspannmast at ( 55 ° 27 ' 8 " N, 13 ° 2' 56 " O55.45222222222213.048888888889 ). Now there is a change of direction to the northeast. About eight supporting masts she goes to the third Abspannmast at ( 55 ° 28 ' 33 "N, 13 ° 4' 2 " O55.47583333333313.067222222222 ).
Now pivots the line in west-north -westerly direction and leads over 15 supporting masts (including 3 angle suspension towers ) south of Västra Ingelstad past the penultimate Abspannmast at ( 55 ° 29 ' 29 " N, 13 ° 8' 18" O55.49138888888913.138333333333 ). From this pole line of a support mast, an angle of the supporting mast and the finishing period of the converter station is running in Krusenberg (55 ° 30 ' 5 " N, 13 ° 8' 44" O55.50138888888913.145555555556 ), which is also referred to as a converter station Arrie and a existing substation was built for 380 kV kV/110.
Overall, the 12 km long overhead line section from 40 masts, each with a cross-arm consists of two conductors. When two conductors of two bundle conductors are used on the overhead line section which are connected at their ends permanently attached to each other and are 6 meters long insulators on the poles. Thus, the overhead line of the Baltic Cable, even though it looks like a bipolar lead, a monopolar line.
Underground cable
The 23 km long line from the converter station Kruse mountain to the anode at the bottom of the Baltic Sea off the Swedish coast consists of two parallel-connected and laid in the ground copper cables, each with 630 mm ² cross-section, insulated with XLPE. The anode are 40 titanium networks, each of which has an area of 20 m² and is covered for protection against mechanical damage with plastic pipes and stones. Because of the way as monopolar line the Baltic Cable performs in its environment in much higher magnetic fields than direct current lines with integrated or installed at a short distance return conductors.
Overhead line
Since radio interference can come from this transmission line, an active harmonic filter was installed in the converter station in Kruse mountain. Because there is no overhead line on the German side section of the Baltic Cables, no such device in Lübeck- Herrenwyk is available.
Bottleneck
The HVDC Baltic Cable could not initially be operated at the maximum possible 600 MW transmission power, as emanating from Lübeck- Herrenwyk 380 - kV three-phase line terminates at the substation Lübeck- Siems and the connection to the German 380 kV grid is still above lines of 220 kV and in some cases even the 110- kV level occurs, which greatly reduces the maximum transferable power and also increases the transmission loss.
Of the original two planned 380 kV lines to Lübeck ( from the nuclear power plant crumbs to Lübeck - Siems and of the converter station Lübeck- Herrenwyk to 380 kV substation Schwerin ) was the construction of the 380 kV line between the nuclear power plant crumbs and the Lübeck- Siems substation deleted according to the E.ON AG. However, perhaps a 380 - kV line will be built to a different 380 kV substation in Schleswig -Holstein, Hamburg and Lower Saxony. The construction of the 380 kV connection from Luebeck to Schwerin - Herrenwyk also will not move forward on environmental grounds.
A new 220 - kV cables and a static var compensator (SVC ) in Lübeck- Siems a transmission power of 600 megawatts has been available since December 2004. The reactive power compensation system was designed and built by Siemens.