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Siemens and Prysmian build submarine interconnector in the Irish Sea

Siemens Energy and Prysmian will build a 2.2 GW high voltage direct current (HVDC) submarine DC interconnector in the Irish Sea.

By Kari Williamson

The order, worth over €1.1 billion, is for the National Grid Electricity Transmission (NGET) and its Scottish counterpart Scottish Power Transmission (SPT), which have founded the special-purpose joint venture NGET/SPT Upgrades Ltd. for the grid expansion project.

The project could be the first submarine interconnector using a DC voltage level of 600 kV – the highest voltage level used to date is 500 kV.

The Western HVDC Link project will provide additional power transmission capacity on Britain’s transmission system, and could help balance supply and demand within the grid sections in light of the continued growth of remote and fluctuating renewable energy sources.

The link is scheduled to be operational by late 2015.

Higher voltage levels in the cables allow higher power transmission capacity with the same diameter of copper in the cable and thus reduce the cost of material used, Siemens explains.

It also means lower transmission losses. The total power loss in the link, caused by the two conversions – from AC to DC and back to AC – as well as by the ohmic resistance of the cables will be less than 3%.

"This order to connect National Grid’s and Scottish Power’s transmission networks underscores our technological leadership in the HVDC field by using the as yet unrivalled voltage level of 600 kV for a submarine interconnector with an also unmatched transmission capacity of 2200 MW. Raising the voltage level in the cable by 20% also enhances its transmission capacity by one-fifth. The transmission losses in the cable are simultaneously reduced by one-third," says Udo Niehage, CEO of the Power Transmission Division of Siemens Energy.

“This milestone reconfirms our undisputed prominent role in the submarine cables sector,” adds Fabio Romeo Executive Vice President Energy Business at Prysmian, “both in terms of market share and track record and in terms of know-how and innovation capabilities. In addition, I would also like to highlight our ever-increasing commitment to the renewable energies sector, with a wide range of high-end products and technologies available to support the development of greener and smarter power grids.”

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