Development of Frequency-Fixed All-Pass Filter-Based Single-Phase Phase-Locked Loop

Samir Gautam,Hafiz Ahmed,Josep M Guerrero,Weidong Xiao,Dylan Dah-Chuan Lu

doi:10.1109/jestpe.2021.3085124

Abstract

Phase-locked loops (PLL) are widely used in the synchronization of grid interfaced power converters. One solution is based on orthogonal signal generation (OSG), which requires the grid frequency information for their appropriate operation. This article developed a new solution to achieve the PLL function for single-phase grid interconnection but eradicate additional frequency feedback loops in the traditional architecture of all-pass filter PLL (APF-PLL). Four new topologies are developed along with their small-signal modeling and dynamic analysis. A thorough comparison among them on their dynamic response, steady-state accuracy, implementation, and disturbance rejection capability is carried out. Finally, the best approach of frequency-fixed (FF) APF-PLL is experimentally evaluated with frequency adaptive APF-PLL and FF PLLs belonging to time delay (TD) and second-order generalized integrator (SOGI) families.

Highlights

S YNCHRONIZATION unit is a key element in grid interfaced converter (GIC) control systems [1]–[3]
One solution is based on orthogonal signal generation (OSG), which requires the grid frequency information for their appropriate operation.This paper developed a new solution to achieve the Phase-locked loops (PLL) function for single-phase grid interconnection but eradicate additional frequency feedback loops in the traditional architecture of all-pass filter PLL (APF-PLL)
A wide variety of OSGs have been recommended for PLL application in the literature, such as TD [6], Hilbert transform (HT) [7], discrete fourier transform (DFT) [8], second-order generalized intergrator (SOGI) [9], all-pass filter (APF) [10] and complex coefficient filter (CCF) [11]

Summary

Introduction

S YNCHRONIZATION unit is a key element in grid interfaced converter (GIC) control systems [1]–[3]. Gridsynchronization based on phase-locked loop has been widely utilized to track the grid phase, frequency, and amplitude in single-phase systems. The PLL is a closed-loop control system constituting three parts, namely: phase detector (PD), loop filter (LF), and voltage-controlled oscillator (VCO) [4]. All single-phase PLLs can be classified into either as (i) power-based or (ii) quadrature based PLL, depending on how the PD is implemented. The latter technique using OSG unit is primarily preferred for its distinct advantages, the absence of second harmonic oscillation and simplified amplitude estimation [5]. A wide variety of OSGs have been recommended for PLL application in the literature, such as TD [6], Hilbert transform (HT) [7], discrete fourier transform (DFT) [8], SOGI [9], all-pass filter (APF) [10] and complex coefficient filter (CCF) [11]

Objectives

Methods

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Conclusion