International Conference on Renewable Energies and Power Quality (ICREPQ’15) La Coruña (Spain), 25 th to 27 th March, 2015 Renewable Energy and Power Quality Journal (RE&PQJ) ISSN 2172-038 X, No.13, April 2015 Robust Control Applied to a Photovoltaic Array Emulator Using Buck Converter L. P. Sampaio and S. A. O. Silva Federal Technological University of Paraná – UTFPR-CP Department of Electrical Engineering Av. Alberto Carazzai, 1640, CEP-86300-000 Cornélio Procópio-PR (Brazil) Phone: +55 (43) 3520-4000, Fax: +55 (43) 3520-4010 - E-mails: sampaio@utfpr.edu.br , augus@utfpr.edu.br Abstract. Considering the increasing use of photovoltaic energy in the actual scenario of electrical power generation, this paper presents the design of an electronic emulator which is able to emulate the characteristics of a PV array. The proposed photovoltaic array emulator is implemented using a mathematical model that represents the equivalent electrical circuit of a photovoltaic cell. The reference signal is obtained from the mathematical model obtained for controlling the dc-dc buck converter, which is used to reproduce the characteristic PV curve (current-voltage). The controller is designed by means of linear matrix inequalities (D-stability criteria in conjunction with H∞ constraints), considering uncertain parameters in the converter model. Finally, from computer simulations, the proposed work can emulate the PV behavior considering atmospheric variations, such as solar radiation and temperature, in order to evaluate the performance of the system and to validate the proposal of the work. Key words PV Emulator, Photovoltaic Array, Robust Control, Linear Matrix Inequalities. 1. Introduction In the last years, a new scenario of electrical power generation has been growing by means of alternative and renewable energies use in conjunction with the utility grid as a distributed generation. Considering the several kinds of renewable energies, the use of photovoltaic energy can be highlighted in the scenario of electrical power generation [1-3]. The electrical power disposable at the output terminals of the photovoltaic panel depends on the manufacturing characteristic and the atmospheric conditions, such as temperature and solar radiation [3]. The temperature is directly related with the PV voltage, such that the increasing of the temperature reduces the PV voltage, while the PV current keeps almost constant. On the other hand, the solar radiation is directly related with the PV current, such that reducing the solar radiation implies in the PV current decreasing, while the PV voltage keeps almost constant. Besides, the relationship between the PV array current and voltage is non linear. The influences of temperature and solar radiations can be observed in Figures 1.a and 1.b, which were obtained considering the behavior of solar panel of SolarWorld Sunmodule Plus SW 245 PV array (Table I). This work aims to implement, by means of numerical simulations, an equipment that emulates the PV array behavior, considering different levels of solar radiation and temperature, in order to provide high flexibility and/or agility in the design development involving the use of PV array in its applications, such as the evaluation of maximum power point tracking techniques, variation of current-voltage and power-voltage profiles, among others [4]. (a) (b) Fig. 1. (a) Influence of solar radiation in the PV current (b) Influence of temperature in the PV voltage. 0 10 20 30 40 0 2 4 6 8 10 Voltage (V) Current (A) 1000 W/m² 8000 W/m² 600 W/m² 400 W/m² 200 W/m² T = 25 ˚C 0 10 20 30 40 0 2 4 6 8 10 Voltage (V) Current (A) 25 ˚C 50˚C 75˚C G=1000 W/m² https://doi.org/10.24084/repqj13.440 665 RE&PQJ, Vol.1, No.13, April 2015