Design of single-phase phase-locked loop based on cascaded second-order generalized integrator

Due to the inevitable existence of various DC bias and higher harmonics in the current power grid, the traditional phase-locked loop (PLL) based on Second-order Generalized Integrator (SOGI) is sensitive to DC bias and has insufficient filtering ability for higher harmonics. To solve this problem, a cascaded second-order generalized integrator structure is proposed, which consists of three cascaded SOGI modules. The first two SOGI modules filter out the higher harmonic and DC components respectively, and then output a pair of orthogonal components through the third SOGI module. Through MATLAB/Simulink modeling simulation and experimental platform verification, the results show that the cascaded SOGI-PLL proposed in this paper has good anti-DC bias interference ability and harmonic suppression effect, which has a good reference significance for the realization of single-phase system.