Enhancing Damping in Single-Phase Grid-Forming Virtual Oscillator Control Inverters: A Feedforward Strategy

The expansion of residential distributed generation systems relies heavily on single-phase inverters for grid integration. However, these inverter-based resources compromise grid stability, mainly due to a lack of inertia and grid strength. To address these issues, grid-forming inverters have been developed, with virtual oscillator control (VOC) emerging as a promising approach due to its superior dynamic performance. However, basic VOC-based inverters cannot provide inertial functionality. Attempts to incorporate virtual inertia into VOCs have significantly reduced the damping factor and led to severe dynamic oscillations. This paper presents a novel technique to improve the dynamic response of single-phase VOC-based inverters by enhancing damping without affecting the virtual inertia and droop functionalities. The effectiveness of the proposed approach is validated through small-signal analysis and extensive experimental testing on a 2.5 kVA single-phase inverter. The results confirm the small-signal model with well-damped dynamic responses in gridconnected mode, without degrading system inertia during stand-alone operation.