Using MVMO for Optimal Tuning of Linear Quadratic Regulators for DFIG-WT

The linear quadratic regulator (LQR) controller is used to enhance the low voltage ride through (LVRT) of doubly-fed induction generator based wind turbines (DFIG-WT). A heuristic optimization method, which is MVMO, is used for optimal design of the LQR weighting matrices Q and R. The objective function of the optimization problem is to minimize the peak short-circuit current and the associated time constants. In order to have realistic values the MVMO problem was constrained by the maximum available machine side converter in order to avoid over-modulation during fault periods. Additionally, the minimum threshold of the stator voltage that will lead to disconnection of the DFIG-WT was considered as a constraint. The results show that the new proposed controller enhanced the LVRT.