The growing scale of offshore wind turbines and projects requires higher efficiency in the grid connection between turbines and substation. In an effort to reduce costs and curtail demand for copper as the essential material of the inter-array wires, Siemens is going ahead with a new 66 kilovolt (kV) solution. The paradigm shift for inter-array systems can be ordered as an option with the Siemens offshore direct drive wind turbines. The 66kV option includes a transformer, a switch-gear, and a cable in between.
The 66kV voltage solution is expected to become standard for future offshore wind projects. As more turbines can be put on each string of turbines due to the higher voltage, fewer strings are needed, and thus fewer array “feeder” cables. This provides additional advantages in logistics and installation. Total savings in the cost of the park grid are estimated to reach up to 15 percent. These savings can however be influenced by project-specific factors including distances between turbines, soil conditions, and project size. Since the supply chain for transformers, switch-gears and other electrical components are sourced from other Siemens Divisions, the company benefited from specialized technology for redesigning its offshore direct drive platform for the 66kV solution.
“Customers can now order our offshore direct drive wind turbines rated at 6, 7, or 8 megawatts with a 66kV option as an addition to the 33kV option. In fact, we are very proud to apply the option at the 712 MW East Anglia ONE project in the UK,” explained Peter Esmann, Product Manager at Siemens Wind Power and Renewables. “This upgrade may seem like a small step towards reducing LCoE. We see it as a future standard, since the benefits increase as projects and turbines increase in size.”