Modern Power Quality Improvement Devices Applied to Electric Railway Systems

Electric railway supplying systems (ERSSs) as one of the foremost and critical loads of the grid have been faced with power quality (PQ) issues all around the world. Due to the various PQ distortion types, and planned priorities, different mitigation methods have been introduced by experts over years and they have been updated based on the emergence of new power electronic-based technologies. These methods mainly deal with harmonic issues, low power factor, imbalance situations, transients, and variation phenomena. The main purpose of this paper is to classify and explain these mitigation technologies including their structure, application and features in detail, which can provide a useful perspective to researchers working in this area.