Basics of active power filters—Design, topology, and control

Abstract

Active power filters (APFs) have emerged as a critical technology for enhancing power quality in electrical power systems. This chapter explores the fundamental aspects of APFs. It begins with a detailed examination of the design principles underlying APFs, focusing on their ability to mitigate harmonics, reactive power, and load imbalances in power systems. The study then navigates through various topologies of APFs, including shunt, series, and hybrid configurations, each tailored to address specific power quality issues. Emphasis is placed on the operational strategies and control algorithms that drive APF functionality, such as instantaneous reactive power theory, synchronous reference frame theory, and estimation-based theory. By dissecting these elements the chapter aims to furnish a comprehensive understanding of APFs, offering valuable insights for engineers and researchers dedicated to improving electrical power systems’ efficiency and reliability. © 2026 Elsevier Inc. All rights reserved.