DC/AC Conversion Efficiency of Grid-Connected Photovoltaic Inverters with Sensorless MPPT

In this paper, we study a photovoltaic system connected to the grid through a DC-AC inverter, the adopted control strategy predicts the future values of the estimated virtual fluxes, currents and power with a discrete time model, which imposes a desired behavior of the active and reactive powers injected to the grid. The active and reactive powers are directly controlled by selecting the switching state of the inverter using direct power control (DPC). The advantages of this strategy are the non-use of the current controllers and Park transformations; in addition, it minimizes the number of electrical sensors. In addition to that, a constant switching frequency is carried out to control the switches. The monitoring of the maximum power generated by the photovoltaic panels is done by the Hill climbing algorithm using the power estimated by the virtual flux. The whole architecture guarantees that the energy conversion is done with a high efficiency such as, reduced losses, a desired power factor, on the other hand the acceptable current distortion rate is ensured by using an SVM modulation technique. Simulations are performed to approve the performance of the proposed control design.