The cascading DSC (Delay Signal Cancellation) algorithm has been widely applied in the calculation of the positive sequence components of fundamental voltage. Due to its characteristics, the DSC has the shortcoming of not functioning properly in delay time. To make up for this shortcoming, this paper proposes a coordinated control method of cascading DSC and PSDR (Positive Sequence Decoupled Resonant). Furthermore, a threshold switch method is proposed to classify the grid faults and choose corresponding control strategy. Based on the proposed method, a corresponding PLL model is built in the Matlab/Simulink platform. As is verified in simulation, when faults occur in the power grid while harmonic wave disturbance exits, the proposed novel PLL can obtain accurate phase information of the grid with low time cost and high precision, and it also weakens the fault’s influence upon the output frequency of PLL.