Nissum Bredning First to Use Siemens SF6-Free Switchgear

Siemens has supplied four panels of the 8VM1 gas-insulated SF6-free high-voltage switchgear (GIS) to Siemens Gamesa Renewable Energy.

The systems have a capacity of 72.5 kilovolts (kV) and were deployed on the Nissum Bredning Vind wind farm in Denmark.

The switchgear protects the wind farm’s four turbines from overloads and short circuits and thereby ensures an uninterruptible power supply, Siemens said.

The metal-encapsulated 8VM1 from the blue GIS portfolio was developed specifically for use in offshore wind turbines. They work with the vacuum circuit-breaker technology and with clean air as the insulating medium instead of sulfur hexafluoride (SF6).

The wind farm operators, Nissum Bredning Vindmøllelaug and Jysk Energi, are relying on a new cable and turbine concept at a voltage of 66kV to connect the four seven-megawatt (MW) wind turbines from Siemens to the grid.

Compared with the usual 33kV grid connection, this new concept is said to increase transmission capacity and lower the cost of laying cables. The 28MW wind farm has been supplying electricity since March.

”In the future, 66 kV could be the standard voltage for offshore turbines. A higher voltage means lower cable-laying costs and also fewer losses. The “cable in pipe” solution also makes it possible to simplify cabling between the turbines. A slimmed-down tower concept helps save even more material. In this case, reduced-weight prototypes that are specially suited to jacket concepts are to be installed,” Siemens said.

The economic prospects of the offshore wind energy technology being tested in the project are expected to demonstrate a significant positive impact on power generation costs. The Danish energy agency DEA anticipates that the components being tested in Nissum Bredning will provide savings on investment and operating costs.