الفهرس 
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Abstract
With the increasing fears of the impacts of the high penetration rates of Photovoltaic (PV) systems, a technical study about their effects on the power quality metrics of the utility grid is required. This thesis investigates a grid-tied PV system that is prepared in the power system computer aided design (PSCAD/EMTDC). The model consists of PV array, DC link capacitor, DC-DC buck converter, three phase six-pulse inverter, AC inductive filter, transformer and a utility grid equivalent model. The research starts with choosing PSCAD as the simulation environment and then by investigating the tasks of the different blocks of the grid-tied PV system model. It also investigates the effect of variable atmospheric conditions (irradiation and temperature) on the performance of the different components in the model. . DC-DC converter and inverter in this model use pulse width modulation (PWM) and sinusoidal pulse width modulation (SPWM) switching techniques, respectively. This thesis investigates the design of static compensator (STATCOM) and surge arresters for voltage dip and overvoltage due to lightning mitigations in the grid-connected PV system. The STATCOM is intended to replace the widely used static Var compensator (SVC). The compensation scheme of the STATCOM is derived using the symmetrical component method. In this work, the 6-pulse STATCOM configuration with insulated-gate bipolar transistor (IGBT) has been designed and the graphic based models of the STATCOM have been developed using the PSCAD/EMTDC. Accordingly, simulations are first carried out to illustrate the use of STATCOM and surge arresters in mitigating voltage problems in a grid-connected PV system. Simulation results prove that the STATCOM is capable of mitigating voltage sag as well as improving power quality of a system.