This book helps the researchers and industrialists working on power quality improvement in renewable energy sources. This book gives information about D-FACTS devices. In this book, the DPFC controller is introduced along with the solar & wind hybrid renewable energy sources for power quality improvement under sag/swell conditions. Different optimal renewable integrated sources and MPPT methods have been highlighted in this book. Modernization in every field of industrialization and increasing living standards of the world population demands more power from the utility. Non-linear loads and renewable source integration with the grid hinder the quality of power. Begining chapters completely dedicated to renewable sources and later on DPFC controller will come.