Inversor CSI multifileiras fotovoltaico de estágio único sem transformador conectado à rede elétrica

Abstract

This document exposes the development of a transformerless single-stage multistring photovoltaic CSI inverter exclusively focused in grid-tied operations, aiming high quality current injection. For this purpose, a rectified sinusoidal current is imposed on the input inductor, allowing the hysteresis trip of the inverter's transistors. The presence of a CL filter at the point of common connection to the grid allows to impose a voltage with a sinusoidal characteristic at the output of the converter, a fact that contributes to the current injection on grid also with a sinusoidal aspect. As the prototype conceived does not contemplate the supply of isolated loads from the network (stand-alone), no rear energy source was inserted in the design of the structure. The input energy is maintained exclusively through two photovoltaic strings. In the control of the structure, it is importante to notice the use of a PLL and a proportional-resonant controller, intended to guarantee the synchronism between the current produced by the converter and the grid voltage. The computational and experimental results obtained demonstrate the operation of the proposed converter with energy efficiency around 87% and total harmonic distortion rate within national and international normative levels.