Study on phase delay compensation of single-phase grid-connected inverter based on SOGI-PLL

Using SOGI-PLL algorithm to control the inverter for pre-synchronous tracking of grid voltage can effectively ensure its safety and reduce the impact on the grid. Considering the phase delay caused by digital control and hardware circuitry, this paper carries out preliminary tracking of the grid voltage based on the SOGI-PLL phase-locking principle, and then extracts the grid phase and the inverter output voltage phase by using the switching phase identification algorithm, and then compensates the phase difference between the two by combining the PI link and the trigonometric formula. After verifying the effectiveness of the compensation method through simulation, a test platform with F28335 chip as the core is built, and the results show that the algorithm can compensate the phase delay of the output voltage of the grid-connected inverter, and the average value of the phase difference is 2.2° before compensation, and the phase difference is less than 0.005° after compensation, which effectively improves the phase tracking accuracy.