Practical Validation of an Adaptive-Gain Fractional-Order PI Controller for Grid-tied PV Systems

This study investigates energy management in grid-connected photovoltaic (PV) systems, with particular emphasis on the regulation of active and reactive power exchanged with the utility grid under dynamic operating conditions. The intermittent nature of solar energy and grid disturbances requires control strategies capable of ensuring fast response and high-power quality. To address these challenges, an adaptive-gain fractional-order proportional–integral (AG-FOPI) controller is proposed for the inner current control loop of a grid-tied PV inverter. The controller combines the robustness and memory properties of fractional-order integration with an adaptive proportional gain to enhance transient performance while preserving steady-state accuracy. The proposed control strategy is implemented and validated using real-time hardware-in-the-loop (HIL) experimentation based on a TI F28379D digital control platform. Experimental results demonstrate fast and accurate tracking of active and reactive power references, with settling times below 10 ms and negligible overshoot during dynamic transitions. In addition, the injected grid current exhibits low harmonic distortion, with total harmonic distortion consistently maintained below 1.8%. These results confirm the practical suitability of the AG-FOPI controller for grid-tied photovoltaic applications.

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