Savitzky–Golay Filter-Based PLL: Modeling and Performance Validation

Abstract

A phase-locked loop (PLL) based on synchronous reference frame (SRF) is a standard PLL that has a simple construction and performs well under undisrupted grid conditions. However, in imbalanced and harmonically disturbed environments, the fundamental grid voltage characteristics deteriorate greatly. Integrating a variety of filters in the control algorithm has been suggested as a solution to address this issue. An optimal low-pass filter characteristic can be achieved with the Savitzky Golay Filter (SGF), which is a zero-phase smoothing filter. The primary objective of this manuscript is to offer a new small-signal design of SGF-based filtration in the SRF-PLL. Using this model, a researcher can easily evaluate the SGF-PLL’s behavior and stability condition. Comparative analysis on performance evaluation is carried out with other PLLs, and the findings represent the principal achievements of the manuscript. This includes a substantial improvement in dynamic response and harmonic profile under transient conditions because of SGF’s superior filtration ability, which is obtained through the convolution process. Moreover, the results are also free of any unnecessary phase delay or distortions due to SGF’s zero-phase filtering characteristics. The results are further validated through mathematical analysis and hardware implementation.