Influence of the Harmonics in Rotor Current on the Wave Shape of the Stator Voltage in a Double-Fed Winddriven Induction Generator

摘要

The double-fed induction generator can, compared with the standard synchronous and asynchronous generator, significant increase the energy output at some windpower sites with a low average windspeed. A converter has to be connected to the rotor, to create a current with a variable frequency. Harmonics on this current induce non-harmonic slip dependent harmonics on the stator current. Both practical experiments and computer simulations have been done, to verify the basic theory presented. The investigation shows that the pulse width modulation methods could be used to reduce the rotor current harmonics. If a proper wave shape is used, no significant stator current harmonics will appear, which could cause voltage variation on a weak grid. The double-fed induction generator with its large speed range and controllable power factor promises some advantages in wind energy conversion, if harmonics induced on the stator current are eliminated. (ERA citation 08:033609)