Table of Contents
ISRN Renewable Energy
Volume 2013, Article ID 406312, 18 pages
http://dx.doi.org/10.1155/2013/406312
Review Article

Analysis of a Three-Phase Grid-Connected PV Power System Using a Modified Dual-Stage Inverter

Department of Electrical Engineering, Power Electronics Institute, Federal University of Santa Catarina, P. O. Box 5119, 88040-970 Florianopolis, SC, Brazil

Received 30 August 2012; Accepted 18 September 2012

Academic Editors: A. Bosio and L. Ozgener

Copyright © 2013 Denizar Cruz Martins. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This paper presents a grid-connected PV system in a centralized configuration constructed through a three-phase dual-stage inverter. For the DC-DC stage the three-phase series resonant converter is chosen thanks to the advantages that it exhibits. However, it is inadequate for the accomplishment of MPPT, due to its efficiency strongly depending on the implemented deadtime and switching frequency. Then, this paper proposes a conceptual modification, that is, a modified dual-stage inverter in which the inverter stage is responsible for both the MPPT and the grid-current control. In addition, the DC-DC converter operates with constant duty cycle and frequency. Such configuration requires a new concept, introduced as Behavior Matching. It serves as a fundamental feature for the DC-DC converter to reproduce the PV array I–V characteristic when they are connected, without control action. The maximum power operating point is found by maximizing the direct axis current, obtained by Park's transformation from the inverter, through the perturbation and observation algorithm. Any specific measurement to realize the MPPT is needed. The galvanic isolation is achieved by using a high-frequency transformer. The structure is appropriate for high power applications, above 10 kW.