Commercial operations have begun at the project by the transmission system operator, TenneT.
The offshore platform for HelWin1, which connects the Nordsee Ost and Meerwind Süd/Ost wind farms, is located approximately 85km off the German coast, north-west of the island of Helgoland.
Siemens Energy Management Division CEO Jan Mrosik said: "This year we have completed the world’s first two large-category offshore grid connections equipped with efficient direct-current technology.
"We also intend to put the next two projects into commercial operation as planned within a few months."
With the HelWin1grid connection, up to 576MW of electricity can be supplied to power more than 700,000 households in Germany.
TenneT TSO board member Lex Hartman said: "With the completion of HelWin1, TenneT now provides around 2,000 MW of transmission capacity in the German North Sea.
"TenneT is therefore in good time fulfilling nearly one third of the expansion targets of the German Federal Government of 6,500 MW by 2020."
The next two grid connections, which include 864MW Sylwin 1 and 690MW HelWin 2, are scheduled to enter service in the first six months of 2015 while the fifth link, 900MW BorWin 3 is planned to begin operations in 2019.
