Rotor flux vector control of DFIG without currents rotor sensor

In this work a new strategy for controlling doubly-fed induction generator is presented. The proposed scheme has two nested control loops. The internal loop regulates the rotor flux, in opposition to the classical approach of controlling the rotor currents. The external loop controls stator currents. Since the machine is connected directly to the grid, this results in a direct control of active and reactive power delivered to the grid. In the presented work rotor flux is controlled without measurement of the rotor currents, reducing complexity and increasing the reliability. The proposed scheme is implemented in a 4KW experimental prototype composed of a doubly-fed induction generator and a squirrel-cage induction machine acting as the primary mover. The DFIG rotor is fed by an industrial inverter properly modified to be controlled by external gate signals generated by a dSPACE 1104 platform, also running the control algorithm and performing data capture. Experimental results are presented and analyzed.