1 Department of Electrical Engineering, Technical University of Denmark2 Center for Electric Power and Energy, Department of Electrical Engineering, Technical University of Denmark3 Department of Wind Energy, Technical University of Denmark4 Wind Energy Systems, Department of Wind Energy, Technical University of Denmark
Direct drive superconducting generators might become attractive in large offshore wind turbines, because the drive train must provide a torque scaling with the radius of the rotor blades as R3 due to limitation of the tip speed of the blades. We have previously found that a coated conductor based generator can technically compete with a gear box drive train equivalent to the 5 MW NREL reference turbine . However the price of the coated conductor results in a generator price exceeding the expected price of the entire turbine. MgB2 conductors can be seen as a low cost alternative to the coated conductors, but the operation temperature in range of T = 15-20 K and the engineering current density Je is smaller. We have found that a 16 pole synchronous generator with active diameter D = 4.2 m and length L = 1.5 m based on a MgB2 wire with Je = 70 A/mm2 in approximately 4 Tesla field would result in a wire usage in the order of 330 km. This has the potential to decrease the price of the superconductor wires in the generator by a factor of 10 compared to the coated conductors, but the cryogenics will be a challenge and is discussed. Finally we will use turbine load simulations to discuss the torque events that such a 5 MW generator would experience if installed in the NREL turbine.
Conference Program Book - 2012 Applied Superconductivity Conference (asc 2012), 2012, p. 887-887