Droop Control Using Impedance of Grid-Integrated DFIG within Microgrid

This paper presents a droop control for a stable grid-integrated operation of doubly fed induction generator (DFIG) within microgrid. While the leakage inductances were neglected in the conventional control method, the proposed droop control uses the leakage inductances of DFIG as the output filter inductance by simply just changing the field orientation. This additional output filter inductor improves the system stability by adjusting the output impedance in the microgrid, of which the line impedance is mainly resistive. Also, the virtual impedance method, which is used for the power decoupling and the system stabilization in an inverter-based generator, is introduced to the proposed droop control of DFIG for the case that the leakage inductances are insufficient. To validate the proposed droop control method of DFIG, the simulation and experimental results in the resistive line impedance, where the conventional droop control of DFIG is unstable, are presented.