Proposed FDTC and FDPC Control for WECS Based on DFIG
摘要
In this paper, enhanced direct torque (DTC) and direct power control (DPC) are applied to two-level back-to-back converters to reduce the high ripples encountered in the conventional DTC and DPC controls. The two-level back-to-back converters are connected to the rotor side of the doubly fed induction generator (DFIG) based on a wind energy conversion system (WECS). The proposed FDTC and FDPC strategies rely on the hybridization of fuzzy logic controllers with the conventional DTC and DPC respectively. Moreover, in the FDPC approach, the number of sectors is extended from six to twelve sectors. The fuzzy logic inference system is designed. Using the FDTC the optimum voltage vector can be selected based on the flux and torque errors according to the position of the rotor flux. On the other hand, for the DPC, the suitable voltage vector is selected based on the active and reactive power errors according to the position of the grid-side converter (GSC) voltage vectors. MATLAB/Simulink performed extensive simulations. The results demonstrated the effectiveness of the FDTC and FDPC, which offer higher performances in transient and steady-state operation than the conventional methods (DTC and DPC), with a significant reduction in power ripples and feeding the grid with low current THD (less than 5%) which confirms with the IEEE standards.