High Temperature Superconducting (HTS) generator for a large-scale wind power generation system draws much attention as a contemporary research item. Excitation systems in HTS generators, particularly brushless HTS exciters are a new challenge.This paper deals with the performance analysis of a 10 kW HTS wind power generator with brushless exciter and examines application possibility of the generator for wind turbines through hardware integration with the exciter. To supply DC current into the HTS coils, a brushless exciter was adopted in the generator. The field current of the generator supplied by the brushless exciter passed through the HTS coil without any mechanical connections. The HTS generator, which consisted of 6 pole racetrack type HTS coils for rotor and 36 slots copper windings for stator, was designed and fabricated. The HTS coils were mounted in a vacuum vessel integrated into the rotor, and cooled down by thermo-syphon cooling method with a cryogenic refrigerator. Through the physical fabrication of the machine, we confirmed several important results as follows. The rated output power of the generator reached to 10 kW at 300 rpm, and the operating temperature was maintained at 30 K by the cooling method. The operating field current was 95 A at operating temperature. When the performance results of the conventional power supply and the brushless exciter were compared, the magnetic flux densities of the generators were almost identical, and the total harmonic distortion of the output voltage of the generator using the brushless exciter was 3.2% which is under the IEEE standard limit of 5%. The results will be utilized to practical design of a generator with brushless exciter through which the heat loss reduction of the field winding and the simplicity of the structure of a large-scale HTS wind power generator will be achieved.
|Submitters Country||Rep. of Korea|