A three-phase three wire grid-connect photovoltaic energy source with Sepic converter to track the Maximum Power Point

This paper presents modeling and control of a grid connected photovoltaic plant. The system consists of a PV cell, a Sepic DC-DC converter used for Maximum Power Point Tracking (MPPT), a three-phase grid converter. A nonlinear control technique of a three-phase inverter is proposed to compensate unbalanced load currents. It allows full control of DC bus voltage, while controlling power flow from the PV cells to the system and guarantying balanced sinusoidal grid currents at unity power factor under varying solar irradiation. Moreover, a sliding mode control technique for a Sepic DC-DC converter is used to extract the MPPT. The proposed control techniques have shown good performance. The system is validated using the “Power system Blockset” simulator under various values of the solar irradiation.