Swepol

SwePol is the name of a 254.05 km long monopolar high voltage direct current (HVDC ) that the power grids of Poland and Sweden combined.

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The HVDC SwePol went in 2000. It has an operating voltage of 450 kV and a maximum transmission capacity of 600 MW. It has the fourth-longest at the time of high-voltage submarine cable in the world. The SwePol coexists with 239.28 km Seekabelabschnitt of two land cable sections, one of 2.22 km in length in Sweden long from the Baltic coast to the converter station in a former quarry in Stärnö and a 12.55 km in Poland from the landfall point in Ustka to the converter station Bruskowo Wielkie.

The high-voltage cable has a cross-section of 2100 mm ². In contrast to other systems, the monopolar HVDC SwePol not used as the ground return conductor but separate cable. This consist in the Baltic Sea consists of two parallel cables with 630 mm ² and the surface sections of a cable with 1100 mm ² cross-section. The cable for the return conductor are designed for a voltage of 24 kV. Grounding is in the converter station Bruskowo Wielkie.

In both stations smoothing reactors are used with an inductance of 225 mH, which are called air coils with a weight of 27.5 t run and located on the high voltage side.

A harmonic filter filters are two stations each with four used the. To 11, which is 13, the 24th and the 36th harmonic coordinated and consist of a series connection of a coil and a capacitor Of these, the filter for the 11th and the 13th harmonic by adjusting the inductance value are tunable. The filters provide a reactive power of 95 MVAr. A further 95 MVAr are available through a capacitor bank.

In both stations, the power converter is designed as a twelve-pulse circuit with thyristors 792 and housed in three 16 m high Thyristortürmen located in a converter hall.

Since inception occurred eleven cable damage, even caused by an anchor, and once by a fishing net. A system fault meant that energy was fed by Sweden in the Polish electricity network. On 14 February 2005 burned in polish converter station the smoothing reactor; they had to be in a 20-hour action replaced by a new then. Two fires in the harmonic filters did a redesign of the filter is necessary.