Saturation controller-based direct power control for doubly-fed induction generator

Abstract

This paper proposes a novel direct power control (DPC) scheme for doubly-fed induction generator (DFIG). Unlike the conventional DPC using hysteresis comparators, the proposed DPC utilizes nonlinear saturation controllers for the voltage vector selection and duty ratio modulation. This makes the calculation of the duty ratios of the voltage vectors much simpler and independent of DFIG parameters. The effect of DFIG rotor speed variations on the power ripples is considered in the proposed DPC by designing an adaptive bandwidth for the saturation controller. The proposed DPC scheme can significantly reduce the power ripples using a fixed switching frequency while preserving most of the intrinsic merits of the conventional DPC, such as fast dynamics, low parameter dependence, and easy implementation. The effectiveness of the proposed DPC scheme is confirmed by simulation results for a 2-MW DFIG-based WECS in MATLAB/Simulink.