Design of Gear-Less Wind Turbine Variable Speed Generators

摘要

If the use of gear boxes in grid connected wind turbines could be eliminated with convertor connected low speed generators, a reduction of cost and weight of the plant could be possible. Studies of these generators have been performed within the Swedish wind energy research program. Earlier designs of gearless low speed generators have often had fixed speed operation with the stator connected directly to the grid. The generator volume will then be much larger than the volume of a generator with a gear box, as the volume is approximately proportional to the rated torque. However, if the generator is connected to a convertor in order to allow variable speed operation, it will be possible to use frequencies higher than the grid frequency. With higher frequency the magnetic flux in the generator will be reduced, which makes it possible to design the machine with less iron. This will reduce the weight and cost of the generators. The design results form this study of low speed synchrounous and induction generators in the rated range of 200 to 4000 kW are presented in this paper together with comparative designs of standard machines. (ERA citation 12:028505)