Voltage Control in LV Distribution Grid Using AC Voltage Compensator with Bipolar AC/AC Matrix Choppers

The modern low-voltage distribution system is exposed to frequent changes in voltage amplitude due to the presence of high-power receivers with variable operating characteristics as well as distributed renewable energy sources whose generation levels depend on weather conditions. Maintaining the appropriate parameters related to power quality in the context of permissible voltage levels more and more often requires the use of additional voltage regulators. These are static systems in which the values of taps on transformers are changed, or dynamic compensators using power electronic converters. This article presents the continuation of research on one of the proposals of AC voltage compensators based on a bipolar AC/AC converter. The general properties of the presented system are reviewed and an analysis of the range of generated output voltages depending on the phase shift of the compensating voltage are presented. The next part of the article presents the formulas for calculating the duty cycle factors for the control functions of individual converters. The verification of the determined dependencies is presented on the basis of simulation tests of the proposed system. At the end of this article, the disadvantages of the proposed open-loop control system regulation and a proposal for further research are indicated.