ÇUKUROVA UNIVERSITY INSTITUTE OF NATURAL AND APPLIED ...

1. INTRODUCTION Mustafa İNCİ
1. INTRODUCTION
The study in this thesis consists of the design and control of Dynamic Voltage
Restorer in medium power systems. The content and aim of study is provided
comprehensively below.
1.1. Background
Electrical power quality become an important issue because of the change in
the characteristics of loads connected to power system due to development of
technology and increase in electricity demand. Voltage, current, frequency deviations
and waveform distortions that cause equipment failure, economical loss and several
negative effects are known as power quality problems.
The most severe power quality problems in electrical systems are called as
voltage sag and swell. Voltage sag is known as short duration reductions in the rms
voltage. Another problem, voltage swell is defined as an increase in the rms voltage.
Several custom power devices such as UPS, DVR, static series compensator etc.
have been improved to solve these problems. Among these several custom power
devices, Dynamic Voltage Restorer (DVR) is an effective solution to solve these
power quality problems.
1.2. DVR
The dynamic voltage restorer (DVR) is the most effective and economical
custom power device applied to protect sensitive loads from voltage sags and swells.
Dynamic voltage restorer is a series connected device located between sensitive load
and grid in system, it both detects voltage sags/swell problems and injects controlled
voltage to system. To perform this process, a conventional DVR consists of inverter,
dc-link capacitor, filter and transformer which will be extensively explained in thesis.
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