This book introduces advanced thyristor-based shunt hybrid active power filters (HAPFs) for power quality improvement in power grids, which are characterized by a low dc-link operating voltage and a wide compensation range. This means they can overcome the high dc-link voltage requirement of conventional active power filters and the narrow compensation range problem of LC-coupling hybrid active power filters. Consisting of 10 chapters, the book discusses the principle, design, control and hardware implementation of thyristor-based hybrid active power filters. It covers 1) V-I characteristics, cost analysis, power loss and reliability studies of different power filters; 2) mitigation of the harmonic injection technique for thyristor-controlled parts; 3)