Enhanced Half-Cycle Oscillator for Robust and Fast Single-Phase Orthogonal Signal Generation and Grid Synchronization

Full-cycle discrete-time oscillators offer strong DC offset and harmonic rejection for orthogonal signal generation (OSG) in single-phase systems, but suffer from sluggish dynamic response due to their long filtering window. This article addresses this limitation by analyzing a full-window averaged discrete-time oscillator and deriving a new half-window discrete oscillator (HWDO) structure with improved dynamic response while preserving orthogonality and harmonic filtering capabilities. It is further shown that DC-offset leakage in the$\boldsymbol{\beta}$-component is inherent to half-cycle realizations, and a lightweight compensation scheme is proposed to restore DC-offset immunity without compromising harmonic attenuation. The resulting HWDO-based OSG is combined with a successive phasor-based frequency estimator for adaptive tracking of grid parameters, and its performance is assessed in real time using an OPAL-RT platform under DC offset, harmonics, phase jumps, magnitude steps, and frequency deviations. Results demonstrate a one-cycle ($\boldsymbol{\approx}$20 ms) settling time during transients, with robust performance competitive with established open-loop schemes.