A novel front-end multilevel converter for renewable energy systems in smart grids

Abstract

The integration of renewable energy systems into smart grids requires dc-to-ac power electronics converters for adapting the voltage levels of both sides. In this context, a novel topology of front-end multilevel dc-to-ac converter is proposed in order to enhance the integration of renewable energy systems into smart grids, preventing power quality problems. The proposed converter is designed to operate as a grid-tied inverter, imposing controlled sinusoidal grid currents in phase opposition with the power grid voltage, and establishing five distinct voltage levels to improve the current waveform. The dc side is suitable to be connected directly to a set of photovoltaic solar panels with an appropriated voltage level, or to an external dc-to-dc intermediary converter used to interface other renewable energy sources. An entire analysis of the hardware design and the operation principle is presented, including the adopted control strategy for the proposed front-end converter in conditions of current control. An accurate computational validation under realistic operating conditions for a significant operating power range is presented using a dedicated power electronics simulation software, where the obtained results show the advantages and the convenience of the proposed front-end converter in detriment of the classical solutions.