Power Quality Improvement in a Three-Phase Grid Tied Photovoltaic System Supplying Unbalanced and Nonlinear Loads

Abstract

This paper is focused on the improvement of the current quality at the Point of Common Coupling (PCC) of a three-phase grid connected photovoltaic system supplying unbalanced and nonlinear loads. The photovoltaic (PV) system is composed of a PV generator interfaced to the grid via a DC–DC power stage connected to a grid-tied inverter. Therefore, to improve the grid current quality at the PCC, the PV inverter is performed as a shunt active power filter in addition to its main task which is the injection of the PV generated power. Thus, this paper proposes a novel and efficient algorithm aimed to extract the correct disturbing current introduced by the nonlinear and unbalanced loads. This disturbing current including the reactive power, harmonic and unbalanced currents, is considered as the reference current in the effective control strategy of the PV inverter. Therefore, the good obtained simulated results point out the effectiveness and the reliability of the proposed algorithm to improve the quality of the grid current and compensate the disturbing current by eliminating the reactive and unbalanced currents and reducing the total harmonic distortion with a fast dynamic response.