Reactive Power Compensation and Harmonics Elimination at Medium-Voltage Using Hexagram Converter

This paper introduced Hexagram converter - a new type of multilevel converter for reactive power compensation and harmonics elimination at Medium-Voltage (MV) grids to improve the power quality. The Hexagram converter is composed of six three-phase two-level Voltage Source Converters (VSCs) interconnected through the inductors, and has the advantages of modular structure with easy construction, even and much reduced voltage stress, and easy control. A four-dimensional control method which is composed of three two-level One-Cycle Controllers (OCC) is proposed for the Hexagram converter system. The reactive power compensation and harmonics elimination function has been verified with both simulation model and experimental prototype.