Abstract
Since wind power generation systems operate at very low rotation speeds, synchronous generators that apply hightemperature superconductors (HTS) to the field windings provide merits such as significant reductions in size/weight and improved rating/partial load efficiency. In this study, a conceptual structure of the HTS generators with a salient-pole iron rotor and racetrack-shaped HTS field coils was proposed. The electrical designs of the large-scale salient-pole HTS generators were prepared using the design program developed. In the design, operating field current was determined from the allowable HTS coil heat loss, which was calculated using three-dimensional magnetic flux analysis. The influence of magnetic flux density in rotor iron cores and the number of poles on elements of main-generator performance such as generator weight, generator efficiency and the required HTS length were clarified. Furthermore, the suitable stator outer diameter for a given output power was studied in order to obtain satisfactory generator performance. Machine parameters were determined considering these results, and electrical designs of 5-10 MW HTS generators were created under an operating temperature of 77 K.
