High-Performance Fuzzy Fractional-Order PID-Based Control Strategy for Grid-Tied Photovoltaic Systems with Active Power Filtering Capability

Currently, meeting grid standards for grid-connected photovoltaic (PV) solar power systems is a major challenge, particularly in terms of energy quality under conditions of non-linear loads, fluctuations in solar radiation, and parameter uncertainties. Conventional strategies based on proportional–integral–derivative (PID) regulators often suffer from limited robustness, higher total harmonic distortion (THD) of current, and noticeable fluctuations in voltage and power. To address these limitations, this work proposes a high-performance control strategy based on a fuzzy fractional-order PID (FFOPID) controller for a grid-connected PV system with efficient energy filtering capability. The proposed approach combines the robustness of fuzzy logic with the flexibility and memory characteristics of fractional-order control to regulate the DC-link voltage, ensure a unity power factor, reduce THD, and enhance dynamic performance. A systematic design methodology is developed to determine and optimize the FFOPID parameters. The studied system includes a PV array, a two-level inverter using space vector modulation, an inductive filter, a nonlinear load, and the utility grid. The proposed method is validated through MATLAB simulations and compared with the PI approach. Results demonstrate that the FFOPID significantly improves the overall system performance. In particular, the THD of the grid current is reduced from 4.05% with the PI to 0.63% with the proposed method. In addition, DC-link voltage fluctuations are minimized, and power oscillations are effectively suppressed. Stable operation is also maintained under sudden variations in solar irradiance and load conditions, confirming the effectiveness of the proposed approach for advanced grid-connected PV systems requiring high power quality.