Direct Power Control of Doubly Fed Induction Generator Using Extended Power Theory Under Unbalanced Network

This paper proposes a novel DPC method for the DFIG power control system. The proposed DPC method is based on extended power theory rather than conventional instantaneous power theory. The proposed method calculates the rotor reference voltage based on the principle of deadbeat power control. Then, the rotor reference voltage is synthesized using space vector modulation (SVM). As a result, the switching frequency is constant, and satisfactory control performance is achieved under both balanced and unbalanced network conditions. This technique achieves the control targets of ensuring a constant stator-side active power, constant extended reactive power and sinusoidal stator currents without power compensation terms or other measures under unbalanced network conditions. Different from other DPC-SVM methods, the phase-locked loop (PLL) block is eliminated, and the whole structure of the control system is simple and easy to use. No parameters need to be tuned in the proposed method. The effectiveness of the proposed method is validated by the presented simulation and experimental results on a 1.5 kW laboratory DFIG control system.