Reference voltage optimizer for maximum power point tracking in triphase grid-connected photovoltaic systems

• Maximum power point tracking (MPPT) in photovoltaic (PV) arrays is addressed.
• PV system including a PV panel, a PWM DC/AC inverter connected to triphase grid.
• Voltage reference must be designed so as to achieve maximum power point tracking.
• Nonlinear control of the DC link voltage.
• The power factor correction (PFC) requirement must be satisfactorily realized.

The problem of maximum power point tracking (MPPT) in photovoltaic (PV) arrays is addressed considering a PV system including a PV panel, a PWM DC/AC inverter connected to triphase grid. Interestingly, the proposed PV system features higher reliability and reduced cost as it involves no chopper and no radiation/temperature sensors, unlike standard systems. We seek the achievement of three control objectives: (i) the voltage reference must be designed so as to achieve maximum power point tracking (MPPT), (ii) the DC link voltage must be tightly regulated over a wide range voltage-reference variation, (iii) and the power factor correction (PFC) requirement must be satisfactorily realized. To meet these objectives, a multiloop controller is designed, using nonlinear design techniques, based on the nonlinear system model. Then, it is formally demonstrated that the proposed controller actually meets the desired control objectives.