Electromagnetic Fault Analysis of Superconducting Wind Generator with Different Topologies

Superconducting (SC) direct-drive wind generators are one of the best candidates for the offshore wind energy applications. The gearbox that exists in the traditional wind generators can be removed. Using superconductors in the armature and excitation windings will largely increase the machine torque density. However, the synchronous reactance in a traditional superconducting synchronous machine is usually low due to its large air gap. Consequently, operating faults will largely threat the machine itself. Also, the superconductor needs to work in the low temperature, usually around 30 K. The magnetic field around it and the current flows in it are also limited. Thus, to improve the machine reliability, the superconducting system needs to be taken care. In this paper, a double stator superconducting flux modulation machine (DSSFMM) is studied and its fault performances are analyzed. From the results, both fault current and fault torque in this kind of machine are low. It is also indicated that the AC loss of the SC coils during fault condition is low.