Unbalanced faults analysis in grid - Connected PV system

Abstract

A search for replacement of non-renewable energy leads to a new founding that is renewable energy which is unlimited energy source. One of the renewable energy is solar energy where photovoltaic (PV) array is used to convert the energy from the sun to electrical energy. PV is widely use in the grid-connected system nowadays. Since the founding of this method, the technology of extracting solar energy from photovoltaic array into grid network system has been growing rapidly. However, with the best installation method the photovoltaic system could not guarantee the system is immune to fault and its effects. The existence of fault in the grid system may cause a drop in the outputs and will drop even lower with penetration of photovoltaic devices in the system. This paper presents the effects of faults penetration inside the grid-connected PV system with three unbalanced faults being tested for this purpose and compare the results obtained. To observe the effects of these faults, a model of grid-connected PV system is built using MATLAB® 2009/Simulink with the help of Simscape and SimPowerSystems toolboxes. First, a PV system is developed in order to make the photovoltaic sourcing the system using a solar cell lumped with 70 others cell to make a PV module. With the help of a booster, the PV system voltage output is regulated and linked to a three-phase inverter circuit. Step-up transformers then are placed at the end of the inverter to replicate real-life utility. Lastly, faults are injected to the connection of inverter and the second transformer of the end of the system is observed for any changes in the voltage magnitude and waveform.