Comparison Study of Superconducting Generators With Multiphase Armature Windings for Large-Scale Direct-Drive Wind Turbines

To reduce the cost of energy and increase the reliability, large-scale direct-drive wind turbines are preferred, especially for the rising offshore wind power generation. Compared to traditional generators, superconducting generators offer many advantages, such as higher power density, higher efficiency at all load, less maintenance, and so on. Therefore, they are regarded as very promising candidates for large-scale direct-drive wind generators with power of 10 MW and larger. For such generators, a great challenge is the full-power converters, which are required as an interface with the grid. Multiphase armature windings are usually used to reduce the current stress of power electronic devices. Two 12-MW nine-phase superconducting generators are designed. Both armature windings consist of three sets of three-phase lap windings, and the primary difference is the phase difference between adjacent phase sets. Using finite element method, the characteristics of the two generators are analyzed and compared, from the point of view of torque performance, eddy-current losses on the damping shell, and power conversion system.