Fast Hybrid MPPT Technique for Photovoltaic Applications: Numerical and Experimental Validation

Gianluca Aurilio,Giorgio Graditi,Mario Luiso,Carmine Landi,Massimo Vitelli,Marco Balato

doi:10.1155/2014/125918

Abstract

In PV applications, under mismatching conditions, it is necessary to adopt a maximum power point tracking (MPPT) technique which is able to regulate not only the voltages of the PV modules of the array but also the DC input voltage of the inverter. Such a technique can be considered a hybrid MPPT (HMPPT) technique since it is neither only distributed on the PV modules of the PV array or only centralized at the input of the inverter. In this paper a new HMPPT technique is presented and discussed. Its main advantages are the high MPPT efficiency and the high speed of tracking which are obtained by means of a fast estimate of the optimal values of PV modules voltages and of the input inverter voltage. The new HMPPT technique is compared with simple HMPPT techniques based on the scan of the power versus voltage inverter input characteristic. The theoretical analysis and the results of numerical simulations are widely discussed. Moreover, a laboratory test system, equipped with PV emulators, has been realized and used in order to experimentally validate the proposed technique.

Highlights

In PV applications, the maximum power point (MPP) of the power versus voltage (P-V) PV characteristic must be continuously tracked in order to extract the maximum energy
The hybrid MPPT (HMPPT) technique based on the coupled adoption of the perturb and observe (P&O) distributed MPPT (DMPPT) technique and the central MPPT (CMPPT) technique using the scan of the P-V characteristic of the string of self-controlled PV module (SCPVM) will be called HMPPT S technique
That is in order to obtain the experimental I-V and P-V static characteristics of the emulated PV modules and of the SCPVMs

Summary

Introduction

In PV applications, the maximum power point (MPP) of the power versus voltage (P-V) PV characteristic must be continuously tracked in order to extract the maximum energy. Belongs to an optimal range whose position and amplitude depend on the number of SCPVMs in the string, on the atmospheric operating conditions characterizing each PV module (irradiance and temperature values), on the voltage and current ratings of the physical devices the power stages of SCPVMs are made of, and on the adopted DC/DC converter topology. The HMPPT technique based on the coupled adoption of the P&O DMPPT technique and the CMPPT technique using the scan of the P-V characteristic of the string of SCPVMs will be called HMPPT S technique Another possible HMPPT technique is based on a strategy in which the CMPPT and the DMPPT techniques exploit an algorithm aimed at evaluating a proper starting set of voltage reference values for the PV modules and the inverter [34].

Working Principle of the FEMPV Algorithm

Simulation Results

Hardware Implementation

Experimental Results

Conclusions