الفهرس 
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Abstract
Due to the effects of global warming from greenhouse gas released to the atmosphere by combustion of fossil fuels, high prices of fossil fuels and their unsteady supply, researchers are becoming more concerned in the renewable energy sources. Renewable energy generated from sources such as wind, solar, biomass etc. are either utilized on their own (standalone mode) or connected to the national grid. Renewable energy sources are cheaper, clean and readily available as they can be used again and again. On the other hand renewable energy sources do not produce constant amount of energy throughout the day and hence they need a good control design. To connect the energy generated from these renewable energy sources to the grid, a voltage source inverter is usually used to convert DC power to AC power. The output of this converter has high order harmonics originating from its high switching frequency. These harmonics should be filtered to prevent their effects on equipment connected to the grid. Several different types of filters as L- filter, LC-filter etc. can be used to filter these harmonics but LCL filters have been known to have high attenuation of the harmonics and allow the use of smaller values of inductors and capacitors which makes it cheaper and less bulky than the others. However the LCL filters produce resonance around its resonant frequency. This resonance causes oscillations and hence should be damped. The objectives of this thesis are to design the control of the voltage source inverter, the LCL filter and its active damping methods. The control of the system is implemented using PI controllers and synchronization with the grid using phase locked loop (PLL). The designed grid connected renewable energy system is simulated using MATLAB/SIMULINK software.