Multilevel Converters for Step-Up-Transformer-Less Direct Integration of Renewable Generation Units with Medium Voltage Smart Microgrids

Abstract

AbstractFor grid integration of renewable generation units, a power frequency transformer operated at 50 or 60 Hz is generally used to step-up the low output voltage (usually ≤690 V) to the medium voltage level (typically 6–36 kV). Because of the heavy weight and large size of the power frequency step-up transformer, the grid integration system can be expensive and complex for installation and maintenance. To achieve a compact and lightweight direct grid connection, a medium voltage multilevel converter may be an alternative approach. Different multilevel converter topologies with switching and control issues are analyzed for their medium voltage applications. The practical implementation issues are also reported in this chapter. It is expected that the medium voltage multilevel converter would have great potential for future renewable generation and smart microgrid applications.KeywordsMedium and large scaleRenewable power generationGrid integrationMultilevel convertersStep-up-transformer-less