A Novel Grid Connection Method for DFIG based on Direct Power Control

This paper proposes a grid-connection control strategy for doubly fed induction generator (DFIG) wind power systems based on direct virtual stator active and reactive power control. The proposed control strategy, named as Direct Virtual Power Control (DVPC), is achieved without proportional-integral (PI) regulator. It requires grid voltages, rotor currents, and rotor position information only. Using the proposed control strategy, a soft grid connection can be achieved without alternate control strategies. To validate the proposed method, a digital signal process (DSP) and complex programmable logic device (CPLD) based 7.5KW experimental prototype is build up. Experimental results are provided to verify the theoretical findings, which include the improved dynamic response and soft grid-connection.