Double Fundamental Frequency PLL Based on Dual Bandpass Filter Structure

In order to solve the problem of synchronization between grid inverter and grid voltage, and improve the detection speed and the precision for the positive-sequence component. Based on dual band pass filter structure, this paper puts forward a new type called double fundamental frequency phase locked loop (DFF-PLL) to measure the double fundamental frequency of positive-sequence component, this method can achieve fast and effectively synchronous with power grid. The principle of DFF-PLL is introduced in detail in this paper. Using a band pass filter eliminates the DC bias and harmonics of input voltage. The performance of DFF-PLL is verified by using simulation and experimental results. Compared with traditional PLL, this method improves the detection speed and accuracy under unbalanced grid voltages.