A Decoupled Control Study of a Grid-Connected Photovoltaic Power System

In this work, we describe a control of grid-connected photovoltaic power system. The control is based on the decoupling of the active and reactive currents. It permits to indirectly control active and reactive powers injected into the grid. The control strategy is based on the decoupling of the inverter output currents to active and reactive currents using the Park transformation. The decoupled currents (active and reactive) are compared with the reference values. The reference active current is calculated from the DC regulator output, the reactive current reference is set to zero to ensure a unit power factor. To reduce the voltage variations of the DC bus, we add a PI regulator with anti-windup compensation. Due to non-linear I-V characteristics of PVs generators and environmental conditions, the PVs generators give maximum power only at a single point. A DC/DC converter controlled by MPPT is introduced at the output of the PVs generators to track the maximum power point (MPP). MATLAB/ Simulink environment is used to design and simulate the strategy study. From the obtained results we can conclude that the control strategy used in this work ensures a good performances and stability.