Power Harmonic Suppression based direct vector control for robust DFIG operation during grid voltage distortions

This paper proposes a Power Harmonic Suppression (Damping) (PHS) based reference current generation scheme, which focuses on simultaneous mitigation of harmonic pulsations in electromagnetic torque, stator real and reactive powers, and DC-link voltage while retaining sinusoidal stator and grid currents and unity power factor at grid side. The crux of this PHS method lies in its ability to eliminate the harmonic powers developed in the DFIG stator and grid at 100Hz, 200Hz, 300Hz, 400Hz, and 600 Hz owing to second, fifth, and seventh harmonic grid voltages. This is achieved as a result of the elimination of natural fluxes developed in the DFIG air gap due to second, fifth, and seventh harmonic distortions in grid voltage. For this, a single concurrent reference current generation technique is developed for RSC and GSC to mitigate the oscillations of electromagnetic torque, stator real and reactive powers, and ripples in DC-link voltage. Further, the reference rotor currents (positive, negative, fifth, and seventh sequence) are compared with the actual rotor currents using a PI controller to retain sinusoidal stator and grid currents. The proposed scheme's efficacy is validated with PSCAD/EMTDC simulations and using OPAL-RT OP4510 real-time simulator, on a 2.3 kVA DFIG. A Power Harmonic Suppression (PHS)-based reference current generation technique for simultaneous control of DFIG parameters under harmonically distorted grid voltage is proposed. This is achieved by eliminating the power harmonics (second, fifth, and seventh) in the DFIG at 2 theta s, 4 theta s, 6 theta s, 8 theta s, and 12 theta s under distorted grid voltages, which enables simultaneous elimination of pulsations in stator powers, torque, and DC-link voltage of DFIG while retaining sinusoidal stator and grid currents and unity power factor at grid side. image