Improved Current Control of Three-Phase Grid-Connected Inverter Systems Under the Grid Voltage Distortions

This paper proposes the control method for reducing a total harmonic distortion (THD) of the grid current at the three-phase grid-connected inverter systems when the grid voltages are distorted. The THD of the grid current caused by grid voltage harmonics is derived by considering the phase delay and attenuation due to a hardware low-pass filter. Both the gain and angle of a compensation voltage for suppressing the harmonic currents at the minimum point of THD of the grid current are derived. The simulation and experimental results show the validity of the proposed control method.