Design and simulation of feed-forward decoupling control for a 5 MW Grid-Connected solar PV system aimed at rural electrification in Nigeria

Solar energy is converted into electricity through Photovoltaic (PV) systems. Single-stage power converters are frequently used in large-scale Photovoltaic Systems (PVS) to ensure high efficiency and a straightforward architecture. These converters perform three main functions: grid synchronization, peak power point tracking, and harmonic reduction with current management. This paper focuses on a specific type of single-stage, high-power three-phase Grid-Connected PV System (GCPS) rated at 5 MW that supplies active power to the utility grid. To sustain stability, the system utilises a voltage controller that maintains the DC-link capacitor voltage at 480 V . It also features a Maximum Power Point Tracking (MPPT) system that dynamically adjusts the voltage and current of the solar panel to maximise power output. A synchronised reference frame (dq) controller, which manages both reactive and active power, is integrated into the system. To generate the synchronised reference frame, the proposed log-sigmoid function-based fuzzy logic rule is employed. MATLAB/Simulink simulations demonstrate that under constant irradiance ( 1000 W/m 2 , 25°C ), the PV array delivers 5 MW , with the load consuming 3 MW and the grid exporting 1.7 MW , achieving an efficiency of 94.04% . When irradiance decreases to 500 W/m 2 , the PV output reduces to 2.585 MW , while the load demand is still met at 3 MW with the grid supplying the deficit, yielding 95.05% efficiency . For a temperature drop from 25°C to 10°C , the PV output increases to 5.42 MW , supplying the load ( 3 MW ) and exporting 1.98 MW to the grid with 91.9% efficiency . Under load variation from 3 MW to 4 MW , the system maintains stable operation, achieving the highest efficiency of 94.9% . The results confirm that the proposed Log-Sigmoid Membership Functional Fuzzy Logic Synchronous Reference Frame (LMFFL-SRF) controller enhances stability, achieves unity power factor operation, and ensures robust performance under varying environmental and load conditions.