The detection accuracy of the traditional phase-locked loop technology is disturbed by the direct current(DC)component

negative sequence component and harmonic component when the three-phase grid voltage contains DC component

asymmetrical voltage and serious distortion

which makes it cannot track the frequency and phase of power grid voltage accurately. In order to solve the problems

this paper proposes a synchronization method which combines the sequence-decoupled resonant(SDR)controller and cascaded double second order generalized integrator based software phase-locked loop(CDSOGI-SPLL). The SDR controller is used to separate positive and negative sequence components. The cascaded double second order generalized integrator(CDSOGI)is used to carry out secondary separation and harmonic suppression

and to eliminate the effect of DC component on orthogonal signal of CDSOGI. The simulation and experimental results show that the grid voltage synchronization information can be accurately collected when the three-phase grid voltage contains DC component

asymmetrical voltage and serious distortion. This work is supported by National Natural Science Foundation of China(No. 51377013

No. 51407023).