Better power transmission on Gotland

Breezy southern Gotland was an early favorite for wind power. By the late 1990’s, the Swedish island had an installed wind power capacity of 40 MW (megawatt). To cope with additional wind power generation, the island grid needed an improved way of maintaining power quality. In addition, the local utility GEAB (Gotlands Energi AB) experienced difficulties acquiring the necessary permits to build an additional overhead power transmission line. 

After a series of studies, GEAB was encouraged to build a pioneering HVDC (high-voltage direct current) commercial power transmission link called GotLight. The HVDC technology has the ability to overcome power quality problems that are inherent in wind power generation, and to transmit the power via underground cables. GEAB is a subsidiary of Vattenfall AB, which decided to finance the project together with the Swedish National Energy Administration. 

The project included project management, design, engineering, manufacturing, installation and commissioning, where all phases were completed successfully. It was the world’s first extruded cross linked polyethylene XLPE insulated HVDC underground cable. The innovation gave the 80 kV cables enhanced mechanical strength and flexibility, making them ideal for tough installation conditions as well as for interconnecting grids to improve the stability of transmission networks. The cables could be plough installed in a cost-efficient manner and buried close to each other. 

The transmission link between the wind farm in the southern part of Gotland and the city of Visby has a 50 MW power rating and it has been transmitting renewable power since 1999.

Cable system design and engineering, including two 70 km long XLPE underground cables

70 km

80 kV DC cable system with a 50 MW power rating

1997 - 1999

Gotlands Energi AB

Gotland, Sweden

 

 

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