Contract awarded for advanced cable connecting wind farm and converter station at sea
Wednesday 23 December 2020
TenneT uses the further developed 1,200 square millimeters cable conductor cross-section offshore the first time
Cable with 100 kilograms per meter enables more efficient single connections
Three-phase current cables will connect wind farms with TenneT’s converter platform HelWin beta and DolWin kappa
ZTT wins tender for this two 155kV-AC offshore connections
To transport the electricity from offshore wind farms to land wind power produced off the German North Sea coast is transmitted from two wind farms to one TenneT converter platform each (HelWin beta and DolWin kappa). There the three-phase current is converted into direct current and transported to the converter station on land where to convert the electricity back into three-phase current and fed into the extra-high voltage grid via the neighboring transformer station. The produced offshore electricity is collected in a transformer station platform before TenneT takes over at the offshore converter station with a 155-kilovolt three-phase cable. Global subsea cable manufacturer Zhongtian Technology Submarine Cable Co., Ltd [ZTT for short] has been commissioned for both wind farm connections of five and 16 kilometre respectively. The cable systems will be produced at one of its manufacturing base in Nantong/ China and then transported to Europe. The laying itself will be carried out by the subcontractor asso.subsea (Greece). The first cable laying is planned for summer 2022 to connect Kaskasi II wind farm.
Two cable systems with a conductor cross-section of 630 square millimeters will be used to transmit 342 megawatts on the five-kilometer long route between the wind farm's transformer sta-tion and HelWin beta. Using the HelWin2 grid connection, the electricity is transported over 130 kilometers to the land station in Büttel (Schleswig-Holstein) and fed into the extra-high voltage grid. For the cable laying that will follow in the summer of 2023, TenneT uses the first time the ad-vanced three-phase cable with a conductor cross-section of 1,200 square millimeters, which will transport the almost 242 megawatts from the Gode Wind 3 wind farm via just one cable system. Various cables and pipelines to be crossed pose a particular challenge, and the route, which is over 16 kilometers long, also runs through the Gode Wind 1 wind farm, which is already in opera-tion. Gode Wind 3 is connected to the extra-high voltage grid via DolWin kappa and the associat-ed DolWin6 grid connection in Emden/East (Lower Saxony).
With its operational grid connection projects in Germany and the Netherlands, TenneT provides offshore wind capacities of 8,532 megawatts. Currently TenneT is implementing seven further offshore grid connection projects in both countries.