Low-Complexity Model Predictive Stator Current Control of DFIG Under Harmonic Grid Voltages

This paper proposes a low-complexity model predictive stator current control (LC-MPSCC) strategy of the doubly fed induction generator (DFIG) under harmonic grid voltage conditions. Sinusoidal stator currents are ensured to be injected into the power grid due to the direct control of the stator currents rather than the rotor currents. No extractions of harmonic voltages or currents are needed in the proposed LC-MPSCC strategy. Conventional resonant regulators that are usually adopted to eliminate the harmonic components in the stator currents are also avoided. Thus, the control system complexity can be decreased. To reduce the iterative computation process in the predictive control strategy, a low-complexity method is designed and only two predictions are needed, which is much smaller than the conventional predictive control that needs seven predictions in a two-level three-phase inverter. The low-complexity method enables higher sampling frequency for better steady performance. Finally, simulation and experimental results on a 1-kW DFIG system are provided to validate the effectiveness of the LC-MPSCC strategy.