Passive Control Strategy to Mitigate Sub-synchronous Control Interaction of DFIG-Based Integrated Power Systems

The sub-synchronous control interaction (SSCI) may exist between the wind farm with the doubly-fed induction generators (DFIG) and the series compensated line. The existing mitigation methods to the SSCI by improving the PI control strategy often introduce nonlinear functions and observers, which increases system order and solution difficulty. A passive control strategy is proposed to supper the SSCI. Firstly, the mechanism of the SSCI in the DFIG-based wind farm is analyzed. It is found that the double-loop PI controller of the rotor side converter has a notable impact on the SSCI, hence so it may be improved to mitigate SSCI. Secondly, the passive controller to the rotor side converter is designed based on the Euler-Lagrange (EL) model and the passive theory. This controller mitigates SSCI by finding the steady state point and injecting the damping. Finally, the mitigation effect of the proposed strategy is verified by time domain analysis, and compared with the results with the PI control to validate the control effect of the proposed control strategy against different compensation levels and wind speed.