Sistema fotovoltaico conectado à rede elétrica trifásica com conexão cascata de conversores cc-cc

Abstract

This work presents the study, design and analysis of a PV system consisted of three cascaded DC-DC Boost converters in the first stage of power conversion, while the second stage employs a three-phase inverter (3-L) grid-connected with a L filter, which injects all the active current available from the PV arrays into the grid. Partial shading can affect the performance of the PV systems since it limits the energy available on the PV array, thus, this work employs cascaded DC-DC converters to reduce the effects of partial shading. On the other way, the heuristic MPPT (Maximum Power Point Tracking) techniques can operate at the local maximum points (LMPP) instead the global maximum points (GMPP). Therefore, in order to maximize the global efficiency, as well as to guarantee that the system operates at the GMPP, it is presented four MPPT techniques based on the grey wolf optimization algorithm (GWO). These techniques are denominated as GWO, GWO-Beta, GWO-IC (Incremental Conductance) e GWO-P&O (Perturb and Observe). The performance and effectiveness of the MPPT techniques, as well as of the PV system are measured considering the convergence time, the oscillations in steady state, as well as the efficiency to search the maximum power point by means of simulation and experimental results, using a 3kWp prototype.