Page 108: of Offshore Engineer Magazine (Aug/Sep 2014)

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North Sea

Wind power gains

More than 3.8GW of ofshore wind transmission capacity is being installed by TenneT ofshore northern Europe.

Meg Chesshyre found out more. iemens is making good progress HelWin1 will convert input on the fve offshore high-voltage from the Meerwind Süd/Ost

S and Nordsee Ost wind farms, direct current (HVDC) grid con- nections it is installing for the German- which are currently under construction.

Dutch network operator TenneT. The grid connections have a total trans-

Earlier this year Siemens mission capacity of more than 3.8 installed the 12,000-ton

GW. In June, the 10,500-ton HelWin2

BorWin2 (800 MW) offshore converter platform topside was loaded

TenneT is also tying in DolWin1, 2, 3 converter platform, 130 km off Borkum, The HVDC transmission market is out from Heerema Fabrication Group’s cluster, 165km off Dollard Bay. DolWin1 built by Nordic Yards at its shipyard in expected to double within the next fve fabrication yard at Zwijndrecht, in the was also built by HFG, for client ABB, Warnermünde, in Germany. Siemens is years from a current €2.5 billion. In the

Netherlands. with Heerema Zwijndrecht supplying in a consortium here with Italian cable last 40 years, “Orders for HVDC lines the topsides, and Heerema Vlissingen the specialist Prysmian. This should also The topside was installed last month with a total capacity of 250 gigawatts jacket. Commissioning is ongoing. The be on line in 1H 2015, as will SylWin1 (July), 85km offshore Heligoland, in the (GW) are anticipated for this decade,”

DolWin2 platform was built in Dubai. (864MW), also built by Nordic, to be German Bight on a 4500-ton jacket, built commented Tim Dawidowsky, CEO by Heerema Vlissingen. The installa- installed 160km off Sylt this summer. The sailaway was June 10. The projected tion was be carried out by Heerema The projected windfarms in the BorWin wind farms in the DolWin cluster are:

Marine Contractors’ derrick barge Thialf. wind farm cluster are: Albatros 1, BARD Borkum Riffgrund1, Borkum Riffgrund2,

HelWin2 is an unmanned platform with a Offshore 1, Deutsche Bucht, Global Tech Gode Wind1, Gode Wind2, MEG transmission capacity of 690MW, bridge- 1, and Veja Mate. For Sylwin, the wind Offshore1, Nordsee One, and Trianel linked to HelWin1 (576MW), which farms are Butendiek, Dan Tysk, and Windpark Borkum.

was installed in August 2013. HelWin1 Sandbank. The converter technology used by should be operational later this year, with The most recent order has been for Siemens is called HVDC Plus. This is a

HelWin2 following 1H 2015. BorWin3 (900MW), due to begin com- voltage-sourced converter of the modular

The HelWin2 transmission link mercial operation in 2019, where multi-level converter type. By contract will connect the offshore wind farm Siemens is in a consortium with Petrofac. with the conventional HVDC version,

Amrumbank West, located in the HelWin This is still in the engineering phase. which can only be used in networks with cluster, to the German grid at the Büttel Meanwhile, TenneT is mulling bids for suffcient short-circuit capacity, systems substation. There is capacity on the BorWin4 (900MW) with a contract award using HVDC Plus make it possible to converter platform for further tie-backs. due shortly. start up island networks from scratch, an important prerequisite for operation offshore.

HVDC technology enables the alternat- ing current generated by the wind farms to be converted to low loss direct current.

Siemens says transmission losses per link are less than 3%, not including cable losses. First a number of transformer platforms arranged around the wind farm transform the alternating current before it is converted into direct current on an

HVDC platform. It is transported to land via a submarine cable and then con- verted back into alternating current for onward transmission. HVDC technology is usually used when transmission cable

The HelWin2 converter platform being transported.

lengths reach 80km or longer.

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