A small photovoltaic inverter for grid-connected operation

Oburu, David Katandi
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Solar energy being one of the most promising renewable resources, plays a very significant role in the energy sector of different economies in the world. However, the photovoltaic (PV) system still faces some challenges such as high costs, low efficiency and the photovoltaic (PV) system’s output power intermittent nature as compared to other renewable technologies. This project focuses on three key areas of PV grid-connected inverter control strategies that is the PV Maximum Power Point Tracking (MPPT) using perturb and observe technique, the PV gridconnected Synchronization technique using phase-locked loop (PLL) and PV inverter control using proportionate-integral (PI) technique to control the voltage and the current of the PV gridconnected inverter. The control techniques operate in such a way that during the grid-connected mode, the PV inverter output frequency and the amplitude is controlled by the grid and the inverter operates in a current-controlled mode. The inverter current-controlled mode of operation achieves two requirements that is, the excess energy generated from the PV inverter is transmitted to the grid under no overload condition. During unfavorable weather conditions or overload conditions, both the grid and the PV inverter operate in a voltage-controlled mode in order to maintain a constant frequency and amplitude of the voltage across the load. Simulations in MATLAB/SIMULINK have been used to verify the validity of the proposed system.
Capstone Project submitted to the Department of Engineering, Ashesi University in partial fulfillment of the requirements for the award of Bachelor of Science degree in Electrical and Electronic Engineering, May 2020
grid-connected photovoltaic system, inverter control system, modeling, power conditioning unit