Single-Phase PLL Based on an Adaptive Notch Filter

Abstract

Single-Phase Phase-Locked Loops (PLL) have become a crucial component of grid-tied power converters. PLL accuracy and fast response are important for control and protection purposes, especially in the presence of voltage harmonics and frequency variations. In this paper, a new PLL structure based on an Adaptive Notch Filter (ANF) is presented. This ANF, which generates the orthogonal system of the PLL, is implemented with an All-Pass Filter (APF) having inherent advantages, such as low sensitivity to coefficient rounding when implemented in fixed-point microprocessors and easy implementation in a Digital Signal Processing (DSP). Both simulation with MATLAB/Simulink, and experimental results on a fixed-point DSP, are presented and analyzed to evaluate the performance of the introduced PLL and to support the theoretical development. A set of comparative simulations between the proposed PLL and a some single-phase PLL described in the literature are conducted to validate the method.