In the grid-connected system

due to the existence of a large number of power electronic devices

there are DC components and high-frequency components in the voltage output by the grid-connected inverter. The loop filter of the traditional phase-locked loop is difficult to completely filter the harmonics of the input signal. A phase shift occurs in the output signal of the phase-locked loop. In response to this phenomenon

this paper constructs a second-order band-pass filter (Biquad filter

BF) to effectively suppress the DC component and high-frequency harmonics in the input voltage signal. The quadrature signal in the phase-locked loop is constructed by constructing a second-order generalized integrator ( SOGI). The characteristics of the second-order bandpass filter are analyzed in the article

and the parameters of the second-order bandpass filter are designed. Finally

through the Matlab/Simulink software

the conditions including DC components

high-frequency components

distortion

jumps

etc. The simulation results show that the phase-locked loop based on the second-order band-pass filter can well suppress the DC component and high-frequency component

and effectively eliminate the phase shift caused by unreasonable parameter settings.