الفهرس 
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Abstract
The power-voltage curve of Photovoltaic (PV) array has multi-peaks during partial shading conditions (PSCs), with one global maximum power (GMP) and multiple local peaks. Traditional maximum power point tracking (MPPT) schemes are unable to track the GMP under PSCs. The technique as string inverters enhances the extracted power during PSCs when compared to central inverter approach, but it has negative impact on the PV systems in term of cost and complexity. The recently published String Optimizer Circuit (SOC)-based technology can be employed to get a performance like string inverter technology, while employing just one inverter at the output stage, i.e., at reduced cost. This thesis intends to evaluate the performance of SOC-based PV array under different partial shading conditions compared to the other existing technologies. In this thesis five different technologies with two different PV arrays dimensions (4×2 and 4×3) have been investigated under different partial shading scenarios, namely: central inverter, string inverter, AC Module inverter, SOC-based system with open loop control and SOC-based system with closed loop control. The performance of SOC-based scanning global maximum power point tracking (GMPPT) technology has been improved in the presented work, where closed loop controller for string current is proposed instead of its conventional open-loop control. This has been done by using a PI (Proportional-Integral Controller) to generate an appropriate duty cycle that contributes to setting the required reference current with the assistance of the proposed GMPPT-based scanning technique. The MATLAB/SIMULINK software package has been used to build models of the five technologies under investigation. Finally, the performance of SOC-based system with closed-loop control for a 2×2 PV array versus central inverter technology has been investigated using real time simulator (OPAL-RT, OP4510). All results show that the proposed SOC-based system enhances the extracted power during PSCs when compared to central converter technology. The proposed closed loop current controller improves the amount of obtained PV power in some PSCs when compared to the conventional open-loop control. The proposed SOC-based closed-loop system has the same amount of power as string inverter technology, but at reduced cost.