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Modified TEODI MPPT Technique: Theoretical Analysis and Experimental Validation in Uniform and Mismatching Conditions | IEEE Journals & Magazine | IEEE Xplore

Modified TEODI MPPT Technique: Theoretical Analysis and Experimental Validation in Uniform and Mismatching Conditions


Abstract:

In this paper, the theoretical analysis and the experimental validation of a modified version of the maximum power point tracking technique, that is known with the acrony...Show More

Abstract:

In this paper, the theoretical analysis and the experimental validation of a modified version of the maximum power point tracking technique, that is known with the acronym TEODI, are presented and discussed. The modified version of TEODI (MTEODI) outperforms TEODI in photovoltaic (PV) applications operating under mismatching conditions. The working principle of MTEODI is based on the periodic measurement of the short-circuit currents of the PV units. The knowledge of such currents allows not only the determination of whether mismatching conditions occur but identification of the values of the suitable correction factors, on which the working of MTEODI is based, as well.
Published in: IEEE Journal of Photovoltaics ( Volume: 7, Issue: 2, March 2017)
Page(s): 604 - 613
Date of Publication: 16 December 2016

ISSN Information:


I. Introduction

IN Centralized photovoltaic (PV) architectures, a unique central inverter carries out the so-called central maximum power point tracking (CMPPT), that is, the maximum power point tracking (MPPT) function is carried out on the whole PV array [1]. It is well known that, in mismatching operating conditions (due to shadows, debris, manufacturing tolerances, aging, different orientation of parts of the PV field, etc.), PV systems that adopt CMPPT may exhibit a consistent reduction of the energy efficiency [1] , [2]. In fact, when mismatching conditions occur, the CMPPT controller may be deceived due to the fact that the power versus voltage (P–V) characteristic of the PV array may exhibit more than one peak (due to bypass diodes conduction and/or reverse bias operation of shaded cells). Under such conditions, the operating point of the PV system may remain trapped in the neighborhood of a relative MPP rather than in the neighborhood of the absolute MPP. Moreover, in mismatching conditions, even if the absolute MPP is correctly identified, the associated power is lower than the sum of the available maximum powers that the mismatched modules are able to provide. Distributed maximum power point tracking (DMPPT) architectures [3]–[6] allow us to reduce mismatching losses. They are based on the use of a number of dc–dc conversion stages that carry out the MPPT on as many PV Units (see Fig. 1). A PV unit can be a PV module, a submodule (e.g., half of a PV module), or a group of an arbitrarily small number of PV cells [7]– [15]. In the following, the term string building block (SBB) will be used to identify the set that is composed by a PV unit and by its associated dc–dc conversion stage (see Fig. 1). Strings of SBBs can be put in parallel in order to feed the central inverter (see Fig. 1). The MPPT technique TEODI is an example of the analog MPPT technique that is suitable for DMPPT PV applications and that can be applied to PV units of arbitrarily small size [12]– [15].

Grid-connected PV system with DMPPT.

References

References is not available for this document.