A novel approach to obtain constant DC-link voltage of the grid-connected converter under harmonically grid voltage conditions

The paper proposed a novel approach to obtain constant DC-link voltage of the grid-connected voltage source converter under harmonically distorted grid voltage conditions. Firstly, the mathematical model of the converter was deduced with the consideration of the harmonically grid voltage conditions. According to the expression of DC-link voltage, the control scheme based on the proposed PI+R current control strategy was designed to remove the DC-link voltage ripple. The expression of DC-link voltage is unrelated to the three-phase impedances, which means the operation performance of the converter would not be influenced by the variation of the three-phase impedances. The effectiveness is validated by the simulation results on a 1-MW GSC system.