The performance of three-phase four-wire grid-connected inverter with enhanced power quality

This paper presents the performance of grid-connected inverter when installed in three-phase four-wire distribution system. The inverter is utilized as power converter to inject power. Furthermore, this inverter is also utilized as a shunt active power filter to compensate current unbalance, load current harmonics, and load reactive power demand. It is controlled such a way therefore it draws or supplies fundamental active power from and to grid. The control mechanism is carried out by power balance theory using PI controller. The control system consists of DC voltage regulator, phase-locked loop (PLL), and hysteresis current controller. PI controller is used as DC voltage regulator, which regulates DC-link capacitor voltage to be constant. The performance of this controller is demonstrated through simulation. The results of the simulation show the capability of an inverter to inject power to grid. Particularly for nonlinear load, the current harmonics are compensated effectively.