Research on SPLL of Three-Phase PWM Rectifier Based on Improved DSOGI

Abstract

DSOGI(Double Second Order Generalized Integral play an important role in SPLL(Soft Phase Locked Loop) of three-phase PWM rectifier under three-phase unbalanced, large harmonic and DC component power grid. But it also can cause a large phase-locked frequency oscillation when the grid occurs frequency jump. In order to reduce the oscillation amplitude, the author proposed an improved DSOGI-SPLL which the FIR filters were inserted before integrators. The system was analyzed in frequency domain before and after improvement. Matlab/Simulink software was used to build model and validated this strategy. The results of theoretical analysis and simulation indicate that this strategy can not only retain the original functions of DSOGI-SPLL, but also reduce oscillation amplitude of the phase-locked frequency caused by grid frequency jump. At last, an experiment was built. The results of experiment indicate that the improved DSOGI-SPLL is effective, simple and practical.