Análise de inversores integrados Zeta aplicados em sistemas fotovoltaicos

Abstract

The study of new converter topologies associated with the generation of electricity in photo- voltaic systems has been highlighted in recent years. In this sense, this work will approach the operation analysis of two single-stage integrated structures, both based on the Zeta DC/DC converter operating in discontinuous conduction mode in order to inject current into a single-phase grid-tied. The structures have four keys, where two operate on the positive cycle and two on the negative cycle, with this the analysis can be simplified by observing the behavior in a cycle. For a better use of the generated energy, analysis of control techniques in simple stage structures are carried out, because they usually present greater efficiency and reduced losses. In addition, the power curve generated in our photovoltaic systems assumes non-linear characteristics that make it difficult to use the maximum power. Therefore, it is necessary to use a maximum power point tracking algorithm. In this work, the P&O algorithm will be used, capable of finding a reference voltage that is applied at the input of the integrated converter that acts as a single stage structure, capable of simultaneously carrying out the voltage rise of the photovoltaic array while injecting a sinusoidal current into the grid-tied. The design of controllers depends on modeling the converters and obtaining mathematical representations. In this work, the controller is divided into two meshes; an external voltage grid and an internal current grid. Through simulation results, the operation and feasibility of the integrated zeta inverters to perform the injection of current in the single-phase grid-tied with low harmonic distortion is demonstrated by extracting the maximum power from photovoltaic array.