The contract was won with Danish company Bladt Industries, which will construct the 2,000 ton substation at its site in Aalborg in July 2014.
Semco’s contract includes the offshore commissioning of electrical and technical systems at the substation.
The Nordsee Ost wind plant is due to be completed in 2014 and lies 35 kilometres from the island of Helgoland.
Semco’s vice president, Carsten Nielsen, said: "Semco Maritime has in recent years witnessed significant growth within wind power founded on our extensive experience as an offshore key operator in the North Sea region gained over the past decade."
