Stationary frame control strategy for voltage source inverter under unbalanced and distorted grid voltage

The paper presents the stationary frame control strategy for voltage source inverter (VSI) under unbalanced and distorted grid voltage, which aims at the two alternative control targets, namely 1) balanced and sinusoidal three-phase current; 2) the smooth active and reactive power injected into the power grid. Unlike the conventional method, the proposed strategy requires no complicated and time-consuming grid voltage negative and harmonic components extraction, and no control reference calculation. Moreover, the proposed strategy is implemented in stationary frame, thus the grid voltage fundamental component phase angle by phase lock loop (PLL) can be avoided. Therefore, the control strategy robustness against grid voltage unbalance and distortion disturbance can be essentially guaranteed. The improved reduced order generalized integrator (ROGI) regulators tuned respectively at +50Hz, -50Hz, -250Hz and +350Hz are employed in stationary frame to independently regulate the output three-phase current +50Hz (positive), -50Hz (negative), -250Hz (5th harmonic) and +350Hz (7th harmonic) components. While the ROGI regulators tuned at +100Hz, and vector PI (VPI) regulators tuned at 300Hz are adopted to restrain the VSI active and reactive power pulsation. The availability of the proposed control strategy is validated by the MATLAB/Simulink simulation result on the VSI simulation model.