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Abstract
Power quality is considered as the most important term of the power system network. Power system faces many disturbances which affect the supply waveform, voltage sag and harmonics are the major problems which can cause malfunctioning or tripping of equipment and many other problems on the system. One of the causes of these events is the inrush current during the energization of no-load transformers. The thesis presents an effective and economic solution for the protection of sensitive loads from sags and harmonics using the dynamic voltage restorer (DVR). The performance of the device under different voltage sag types is described, where the voltage sag types are introduced using the different types of short-circuit faults, showing that it can be considered as a proper solution to overcome the sags effects. The robustness of the proposed device are evaluated using the common voltage sag indices, while taking into account voltage and current unbalance percentages, where maintaining the total harmonic distortion percentage of the load voltage within a desired range