Siemens wins maintenance contracts for offshore electric grid connections in the North Sea

After having won the orders to build the two North Sea grid connections HelWin1 and BorWin2 in the summer of this year, Siemens has now also been contracted to carry out their entire maintenance. The two contracts, awarded by the Dutch grid operator TenneT, are Siemens’ first in the emerging field of offshore grid connection maintenance services within Germany and are initially for a period of five years. The two connections provide transfer capacity to the German mainland for several offshore wind farms in the North Sea. Siemens will establish a service base in Lower Saxony close to the coastline for the offshore and onshore converter stations. This enables Siemens to further expand its comprehensive operation & maintenance service portfolio for electricity transmission grids.


"The BorWin2 and HelWin1 projects for integration of the offshore wind farms Veja Mate, Global Tech I and Nordsee Ost into the onshore high-voltage transmission grid will benefit from our many years of experience in this field. As the undisputed market leader, we have so far received orders for connecting offshore wind farms with a rating totaling approximately 4,800 megawatts. Now we are going to aggressively develop our maintenance business in this field as well”, says Dr. Udo Niehage, CEO of the Power Transmission Division within the Energy Sector at Siemens.


The services covered by the contract include preparing the maintenance schedules, coordinating and executing inspections, preventive maintenances and repairs, and providing the related logistics and spare parts management services. To ensure fast customer response, Siemens will set up a service base in Lower Saxony close to the coastline and will staff it with highly qualified personnel. The wind farms are located between 85 and 125 kilometers offshore, to the north-west of the islands of Borkum and Helgoland, and pose special challenges in terms of maintenance and logistics due to their exposure to a harsh maritime environment. The BorWin2 grid connection will have a transmission capacity of up to 800 megawatts (MW) of clean electric power, HelWin1 a capacity of 576 MW. Both connections will be built using high-voltage direct current (HVDC) transmission technology with submarine cables, and are scheduled to be ready for operation in 2013.


Using HVDC technology reduces transmission losses significantly. High-voltage cable links more than 80 kilometers long require HVDC for power transmission due to the fact that a major portion of the electrical energy would be lost as reactive power with an AC connection of that length and power rating. Siemens has developed HVDC Plus for precisely such applications. This modular VSC technology reduces the complexity and thus the installation space needed at offshore platforms.

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