The increasing use of power electronics devices contributes further to the arising of power quality problem that is becoming more and more serious, and has been a great threat to the safety of electric power systems and the national economy as a whole. This Book proposes and develops new efficient methods for power quality events monitoring, detection, and tracking. These methods are mainly based on wavelet multiresolution analysis and rms voltage calculation. These methods have been implemented in laboratory scale prototypes. Furthermore, a new efficient technique for online accurate harmonic estimation has been proposed and simulated. This book is suitable for readers from different disciplines, including college students and instructors, electricity traders, consulting companies, electric utilities, and researchers.