Analysis of low frequency oscillation in single-phase grid-connected inverter

The oscillation phenomenon in single-phase grid-connected inverter with LCL filter is analyzed. MATLAB/Simulink simulation is performed based on the average model of system, which shows that, the oscillation phenomenon occurs in a stable system along with the change of regulating coefficient. The discrete model of grid-connected inverter is deduced by using the stroboscopic sampling method. The system stability is analyzed according to the eigenvalues of Jacobian matrix, which reveals that the Hopf bifurcation occurred in system causes the oscillation phenomenon. The bifurcation point is accurately predicted by analyzing the change of eigenvalues. A method combined with the characteristic equation is given to determine the oscillation frequency. The correctness and validity of theoretical analysis are verified by experiments.