Implementing a Single-Phase Quasi-Z-Source Inverter with the Indirect Current Control Algorithm for a Reconfigurable PV System

摘要

A reconfigurable photovoltaic system based on the structure is developed by combining a single-phase quasi-Z-source inverter and the grid-connected system, and a digital signal processor is used to implement the indirect current control algorithm of the quasi-Z-source inverter. The DC bus voltage and the output voltage can be effectively regulated by shoot-through and nonshoot-through modes. In addition, a zero-point detector circuit with phase-locked loop and power control is employed to facilitate the parallel connection and the output power control of the inverter to the grid. When the grid is under a fault condition, the voltage amplitude and power angle of the system can be regulated using the indirect current control algorithm, and the operation mode can be smoothly changed from the grid-connected mode to island mode. The feasibility of the system model and control algorithm are verified throughout the simulations by using MATLAB/Simulink. Finally, a system prototype was constructed and tested and the results show that the parallel connection of inverter to grid can be successfully implemented using the indirect current control algorithm; besides, different control functions can be also validated.