A Modified PLL Based on Second Order Generalized Integrator for Single-Phase Voltage System

In grid connected system for monitoring single phase voltage parameters such as voltage amplitude, frequency and phase accurately variety of PLL methods are being used recently. In this paper a modified phase locked loop (PLL) system is represented for single phase operations. The mentioned technique offers a modified orthogonal system generation based on second order generalized integrator (SOGI). In this work Park transformation based phase comparator is used where only the quadrature axis component is tuned through PI controller to maintain almost zero phase difference between input and output voltage. This PLL method shows better performance in different abnormal conditions of grid like harmonics, noise, DC offset, voltage sag and so on. For harmonics suppression from input voltage signal, a filter is utilized at the input side of this PLL structure. The obtained simulation results are provided to evaluate the efficiency and accuracy of the mentioned PLL method.