Desviadores de corrente de arquitetura híbrida para compensação de sombreamento parcial em associações série de módulos fotovoltaicos

Abstract

Partial shading has always been an issue since the first photovoltaic systems operation. Since this is just one between many kinds of incompatibility conditions, partial shading not only affects the instantaneous generated power during its occurrence, but also the modules life-time, accelerating the degradation, even if only a part of one module is being shaded. Many are the solutions for this problem, like global maximum power point tracking techniques, modules reconfiguration and also differential power processing of each module. This last one is implemented using integrated converters of various types. Among the known converters, there is a type capable to process only the energy related to partial shading. They are known as current diverters and may be programmed to operate only in the occurrence of partial shading. The Current Diverters are divided in to architectures: PV-to-PV, that process power from module to module, and PV-to-Bus, that process power from each module to the string Bus. The PV-to-PV circuits present several advantages over PV-to-Bus circuits. However, they are affected by a phenomenon here called deviated current accumulation, which makes it difficult the operation and design of some of its elements. In this work, as a solution for this problem, a hybrid architecture, here called PV-to-PV-to-Bus, is proposed, and applicable for many types of circuits, rather capacitive or inductive. First, a study on PV-to-PV circuits and its design feature is made, and an approach to calculate its is proposed. Than, the effects of partial shading in voltages and currents are presented for both architectures, under the same conditions. The proposed circuit showed to be a better voltage equalizer, and with smaller current levels than the PV-to-PV circuits. At last, experimental results for a Buck-Boost Bidirectional are shown in to experiments, one to evaluate the proposed design approach, and the second to evaluate the proposed architecture. The proposed architecture shows results that proves smaller current and better voltage equalization than the PV-to-PV architecture.