Power Quality Improvement by an Active Power Filter in Grid-connected Photovoltaic Systems with Optimized Direct Power Control Strategy

In this article, a grid-connected photovoltaic system with functionality of power quality enhancement is studied. The integration of the photovoltaic generator into the grid takes place in one stage, using a three-phase voltage source inverter. A direct power control algorithm strategy with a new switching table has been proposed to decrease power losses into the voltage source inverter, to enhance power quality, to optimize the control of instantaneous active and reactive powers, and to perform as a multi-function device by incorporating shunt active power filter functionality. In addition to this control strategy, a maximum power point tracking perturb and observe algorithm is applied to the inverter to extract optimal available power from the photovoltaic array. The proposed system can provide the power factor correction, harmonic elimination, reactive power compensation, and simultaneously inject the maximum power available from the photovoltaic array to the load and/or grid. The multifunctional features of the proposed control algorithm are demonstrated using extensive simulation studies and are validated through experimental results.