Evaluating Dynamic Performance of DTC under Grid Disturbance for a Wind Driven DFIG

摘要

This paper presents a direct torque control (DTC) approach combined with a space vector pulse width modulation (SVPWM) strategy for a doubly-fed induction generator (DFIG). The proposed DTC replaces the classic hysteresis controllers with a model predictive (MP) controller to achieve constant switching frequency and to reduce the ripples in the calculated values. The proposed DTC approach is mainly concerned with controlling the rotor side converter (RSC) of the DFIG under grid fault conditions. To validate the effectiveness of the proposed DTC scheme, the DFIG dynamic performance is tested under unbalanced grid conditions. Obtained results show that the proposed DTC approach exhibits better dynamic behavior and improves the DFIG stability during the fault period. The results are also compared with that of conventional DTC method without pulse width modulation (PWM) strategy. From comparison, it can be realized that the proposed DTC proves its compactness for providing improved dynamic performance for the DFIG under up normal grid conditions.