In this book, a three-bus, radial distribution system is proposed to be used as a benchmark for the study of power quality problems (PQPs) and their compensation. To mitigate PQPs in distribution systems, Custom Power Systems (CUPS) devices such as Distribution Static Compensator (D-STATCOM), Dynamic Voltage Restorer (DVR), and Unified Power Quality Conditioner (UPQC) are required. An increasingly popular and practical control technique based on Active Disturbance Rejection Control (ADRC), which is simple and has good disturbance rejection capabilities, is implemented to control CUPS devices....