An eSO-CCF Based Fundamental Component Extraction for Three/Single-Phase System

The Generalized Integrator (GI)-based complex coefficient filter (CCF) is a promising solution for extracting fundamental component of the signals, quadrature signal and grid voltage parameters under distorted grid conditions. It has gained considerable attention in three-phase systems due to its ability to handle complex input signals and its frequency-selective harmonic extraction capabilities. However, under weak-grid conditions with high distortion, harmonics, sub-harmonics, and dc offsets, its performance deteriorates, failing to extract accurate fundamental component of the signals and therefore synchronization signals get affected. This article proposes an enhanced second-order CCF (eSO-CCF) for both three-phase (3ø) and single-phase <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(1\phi)$</tex> systems, capable of extracting fundamental components more accurately and rejecting dc offsets robustly under weak-grid conditions. Performance of the proposed eSO-CCF is validated through MATLAB/SIMULINK simulations and experimental results on an FPGA-based controller, compared with CCF, SO-CCF, and fourth-order-GI/second-order-SOGI.