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The largest HVDC link in the Mediterranean Sea.

The SAPEI HVDC undersea link delivers surplus power from the island of Sardinia, an autonomous region of Italy, to the Italian mainland to help strengthen the power grid near Rome. Italy is today the world’s biggest importer of electrical power, and interconnections like this can deliver enough electricity to supply one million homes.

Terna - Rete Elettrica Nazionale SpA, awarded contracts to ABB in 2006 to supply the HVDC converter stations, one in Fiume Santo, Sardinia and the other in Latina, on the Italian mainland. The subsea cable lies 1,600 meters (5,200 ft) below sea level in the Tyrrhenian Sea, and is the deepest subsea power cable in the world, as well as one of the longest at 420 km, with an additional 15 km of land cables. The SAPEI link is owned and operated by Terna.

The SAPEI HVDC system is a 1,000 MW bipole transmission link, and an important strategic link to ensure a strong connection with Sardinia, the second largest region of Italy. Each pole is rated 500 MW at ±500 kV with 1,000 Ampere as nominal current. SAPEI is also the second HVDC power transmission link from Sardinia to the Italian mainland.

In the 1960s, ABB supplied mercury-arc valves and HVDC control systems to the first HVDC link from Sardinia to the Italian mainland, called the SACOI HVDC link (Sardinia, Corsica, Italy). This was a 200 MW transmission from Codrongianos on Sardinia to San Dalmazio in Tuscany, south of Florence, and was commissioned in 1967. The link also runs over the French island of Corsica.

Main data

Commissioning year: 2011
Power rating: 1,000 MW
No. of poles: 2
AC voltage: 400 kV (both ends)
DC voltage: ±500 kV
Length of DC submarine cables: 2 x 420 km
Length of DC underground cables: 2 x 1 km (Fiume Santo) + 2 x 14 km (Latina)
Main reason for choosing HVDC: Length of sea cable
Application: Interconnecting grids

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