الفهرس 
INTRODUCTION AND PREVIOUS WORKOnly 14 pages are availabe for public view
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Abstract
Renewable energy sources have become a popular alternative electrical energy source. In the last few years the photovoltaic (PV) and wind power generation has been increased significantly. But there are issues for both systems, the intermittent nature of solar energy such as variation of radiation and temperature affects the output power of PV systems and the other problem in wind energy systems is how to obtain power at maximum value with various wind speeds. To overcome these problems, this thesis proposes a hybrid energy system which combines both PV system and a doubly-fed induction generator (DFIG) based wind turbine as an alternative to conventional sources of electrical energy. This was done through the following steps: Firstly, performance enhancement of grid connected PV system by using incremental conductance (IC) maximum power point tracking (MPPT) technique. The main objective of the control is to maintain the MPPT operation under different solar irradiations. The IC technique has numerous significant merits such as, simple, cost effective and easy to implement. The system consist of the PV array supply, DC link capacitor, boost converter, three phase inverter and 3-phase grid connected system. Secondly, investigation and track the MPPT of DFIG-based wind turbines under different wind speeds by using perturb and observe (P&O) technique. The P&O technique is considered one of the best techniques used to obtain the maximum power that can be taken out of wind energy for some features such as low cost, simple structure high dependability and ease of implementation. Finally, investigates the dynamic modeling, design and control strategy of a grid-connected PV/wind hybrid power system. The hybrid power system consists of PV system and a DFIG based wind turbines that are integrated through main DC-bus to enhance the system performance. In addition, an experimental model of a PV system, DFIG-based wind turbine and PV/wind hybrid system are implemented in the laboratory (Smart Systems Labs). The experimental study focuses on analysis the performance of a PV grid system during variation of the environmental conditions. On other hand, it highlights the dynamic response of the DFIG with different wind speed profiles (step and ramp changes). Based on simulation and experimental results, it was obvious that the simulation results were in a good agreement with the experimental results.