Applying a New Resonant Converter with a New Control Method and Improve Reactive Power Capability in the DFIG

This paper presents a new control method for a doubly fed induction generator (DFIG) and a new resonant converter (RC) for grid side converter (GSC). By using this control method, the separated control of active and reactive power will be possible. Also by using the RC, DC link capacitor in conventional two stage AC-DCAC conversion will be omitted. To make conventional two stage AC-DC-AC output current and voltage more useful, a low pass filter should be added between the output and the grid or rotor to smooth out the ac portion. These filters need to be lossless, and was constructed from inductors and capacitors. Capacitors and inductors that were being used in low pass filters structure and also DC link capacitor, in the conventional converters will be used in the resonant circuit of RC. The value of capacitors and their nominal voltage will be decreased. The reactive power capability is subject to several limitations resulting from the voltage, current, and speed, which change with the operating point. In this paper the current limit of reactive power capability will be reclaimed. The simulation results show the new control method and resonant converter has good and lossless performance.

Keywords:

Resonant Converter (RC) , Doubly Fed Induction Generator (DFIG) , Reactive Power Capability , Separated Active and Reactive Power Control