Switchgear and substations

Fljótsdalur substation

Eastern Iceland

Verkís services was project planning, design, tender documents, contracting and design supervision and risk management.

 Sizes: 220 kV and 132 kV
 Project time:  2003 - 2007

Project overview:
The substation is located in east Iceland. It stands at about 50 m a.s.l. and is located at the end of a cable tunnel to the powerhouse complex of the underground powerhouse of Kárahnjúkar HEP. The substation facilitates the transmission of electricity from the 690 MW power station to Fjarðaál aluminium smelter and the interconnection to the 132 kV transmission grid. The substation is owned and operated by Landsnet hf, the Icelandic transmission system operator.

The substation is an important link between the Kárahnjúkar power station and the Fjarðaál aluminium smelter with some connection to the national grid. Reliability was therefore a key issue in the design of the substation.

The substation equipment is housed in a concrete building on two floors with the power transformers in front of the building. The 245 kV switchgear is connected to the six unit transformers in the underground powerhouse by power cables running through the approximately 1.000 m long cable tunnel. Two 245 kV transmission lines, 50 km long, connect the substation to the aluminium smelter and two autotransformers connect the substation to the national grid with approximately 100 MW maximum transmission capacity.

The switchgear is of the SF6 gas insulated indoor type, suitable for direct connection with SF6/air bushings to transmission lines, SF6/oil bushings to power transformers and XLPE cable connections. The splitting of the busbars is a special feature of the 245 kV switchgear, each half connected to three generating units in the power station, one transmission line to the aluminium smelter and one interconnection transformer to the grid.

The substation is equipped with a modern control and protection system and is normally remotely controlled and monitored from a dispatch centre in Reykjavík. The substation building is protected from snow avalanches by a triangular shaped earth filled dam, deflecting avalanches from the building.