Model-Free Predictive Voltage Control of a Grid-Forming Inverter Based on an Ultralocal Predictor

Grid-forming inverters (GFI) have gained significant importance as they are used to supply alternating current (AC) in distributed generation systems and islanded microgrids, where inductive-capacitive-inductive (LCL) output filters are commonly employed to mitigate harmonics injected by voltage-source inverters (VSI). Advantages such as the simple operational principle, fast dynamic response, multivariable control, among others, have contributed to establishing Model Predictive Control (MPC) as a suitable alternative for controlling the inverter systems with LCL filters. However, it presents a significant disadvantage: it relies on the phenomenological model of the system, thus disturbances or random variations in parameters deteriorate control quality and performance. This work proposes the implementation of a model-free voltage predictive control for a grid-forming inverter with LCL filter, based on an ultralocal predictor using only input and output data from the system. The proposed method is validated through simulation analysis and experimental results to demonstrate its real-time applicability.