Abstract:
In recent years, much attention has been paid to the use of multi-megawatt photovoltaic systems in power distribution and over-distribution systems. Also, due to lower costs of photovoltaic systems, grid-connected photovoltaic technology has improved significantly. However, the increasing growth of photovoltaic systems may have adverse consequences for power systems in terms of harmonics, voltage profiles, stability, and so on. Therefore, this dissertation offers the best possible integration of photovoltaic generators into a grid-connected DG converter with multiple photovoltaic panel inputs. The challenging issues in designing, and analysing such systems arise from the complex dynamic model of these systems, which is rooted in nonlinear characteristics of voltage and current in solar modules. In this thesis, a step-by-step process of modelling, designing, and analysing various parts of the system such as: photovoltaic array, DC bus capacitor, voltage source inverter, passive output filters and inverter current controller and DC bus voltage is presented. Also in this thesis a new method for designing DC bus voltage controller based on nonlinear voltage-current characteristic linearization of photovoltaic module is presented and a criterion based on the maximum power sequential controller parameters to improve the performance of this controller is extracted under changes in radiation level. Has been. The results show the satisfactory performance of the whole system and the designed controllers as well as the accuracy of the analytical criteria extracted for the stable operation of the system under various operating conditions.
