A Synchronous Reference Frame based PLL Control for a Grid-Tied Photovoltaic System

Abstract

For grid interconnection of a Photovoltaic (PV) system, there are some vital requirements that are to be addressed. Grid synchronization methods are very vital in the grid interconnected PV system. Therefore, a phase-locked loop (PLL) system is mandatory for the phase identification of the utility system. A Synchronous Reference Frame (SRF) based PLL control for a Grid-tied PV system is described in this paper. This PLL system is analyzed and designed in order to control the inverter in the dq-frame while infusing the grid with required power. To justify the work, a grid tied PV system with all the above discussed components is designed in MATLAB/SIMULINK and its various results have been tested. Here, a PV array with hundred numbers of BPMSX-120 PV panels is taken into consideration. These PV array has ten parallel strings of PV panels and in string consists of ten series connected PV panels. To verify the correctness of the designed PV array, different characteristics of this array have been presented for different environmental conditions. To test the working of maximum power point tracker (MPPT), the PV panel outputs are provided. Eventually, various results like waveforms of the three phase inverter output voltage, injected AC current to the grid, total harmonic distortion analysis etc. are reported in this thesis to justify modeling of the three phase grid and its synchronization with the PV array.