Abstract：Grid synchronization technique is one of the key techniques in the grid-connected operation of distributed power generation systems. In order to solve the problems that there exists second and higher harmonics in the traditional single-phase stationary reference frame phase-locked loop (PLL) and imaginary orthogonal signal is needed for synchronous reference frame PLL which can't totally eliminate grid harmonics at the same time, a new single-phase PLL method without imaginary orthogonal signal generation is put forward. This proposed method embeds a cascade control structure on the basis of the traditional stationary reference frame PLL. The corresponding open-loop system to such structure generates the resonant peak at the grid harmonics which are exported by the phase discriminator so that the corresponding harmonics can be completely eliminated in the closed-loop control and purer frequency, phase and other related information can be extracted by the proposed PLL. Finally, the proposed PLL is tested by the related experiment under different grid conditions. The results how the validity and superiority of this method.
2021, Vol. 22 
