Grid-connected control research of distributed photovoltaic connected to AC distribution network

A lot of harmonic is generated when distributed photovoltaic (PV) connects to the distribution network through inverter. LCL filter is adopted in the grid-connected control system because LCL filter has stronger ability to filter high frequency harmonic than L-type filter. Compared with pulse width modulation (PWM), space vector pulse width modulation (SVPWM) has a higher control accuracy and is easier to implement digital. In the paper, SVPWM controls the inverter to change DC into AC. Then, AC connects to the AC distribution network through LCL filter and transformer. The simulation results show that the frequency and phase of the sine wave output are the same with those of distribution network, which indicates that the designed system of PV connected to distribution network and the adopted grid-connected control method are feasible and effective.