Development of Single-Phase Two-Stage Grid-Connected PV System in PLECS Simulation Program

Abstract

Conventional sources such as oil, natural gas, and coal are the major and more dominant energy sources. Increased fossil fuels consumption via power plants led to global warming due to the rise of CO2 emissions. Therefore, renewable energy sources have attracted more attention. Among those sources, the solar PV systems have gained much more interest due to its reliability and ease of access to its sources. These days the grid-connected PV systems are being heavily employed. This increased penetration, however, presents several challenges to the energy systems. This project aimed to design and simulate the single phase two stage grid-tied PV system to study the behaviour of the system operation and to understand the main challenges facing this type of the system when it is connected to AC grid. The project was developed in three stages to illustrate step by step the design of the main components of the double stage PV system. Using the ideal DC source, the boost converter has been designed with double closed-loop control to interface the high DC load and simulated it using PLECs. The simulation results showed the controller has the robustness and a good performance to regulate the output voltage. The DC/AC inverter with cascade control loops was then designed and modelled using PLECs to interface with single-phase AC grid. The simulation findings demonstrated a good performance of the controller to maintain the DC link voltage and regulate the injected current into the grid. The two topologies of DC/DC boost converter and DC/AC inverter were integrated with single-phase grid and the simulation has been performed in PLECs to illustrate overall behaviour of the system. The PV array and MPPT algorithm were then designed and developed to replace the ideal DC source, to determine the impact of the change of the environmental conditions on the system. The simulation results showed the algorithm of MPPT applied at boost converter could enhance the operating hours for PV systems and effectively optimise the output of power from PV panels. Moreover, the controller in the AC side maintained the power factor at the unity and delivered the grid with power generated by solar panels.