A Review on AC Voltage Variation Compensators in Low Voltage Distribution Network

Power quality is one of the most important aspects of the power system, especially in the distribution system. This system can be affected by such disturbances as short-term voltage sags/swells, long-term voltage increases/decreases over the normative limits, harmonic distortion, interruptions, etc. Maintaining the electricity quality parameters in accordance with the applicable standards in the power distribution system will require the use of additional devices. The scientific literature on the subject indicates a very wide range of different topologies of AC voltage compensators. In this paper, different power electronics-based AC voltage compensator topologies are reviewed that are typically used with distribution energy systems. A summary of the properties and functionalities of the selected topologies has been presented. This review focuses mainly on the different topologies of the Unified Power Quality Controllers (UPQC) and Hybrid Transformers (HT). This review is divided into several sections. The first section presents the topologies used in UPQC and HT. The second section discusses selected control methods for these systems. The third section presents the basic properties of the systems related to compensating changes in the supply voltage and improvement of power quality. The fourth section presents the use of UPQC and HT systems. Finally, a summary and conclusions are presented.