New method for analytical photovoltaic parameters identification: meeting manufacturer’s datasheet for different ambient conditions

At present, photovoltaic energy is one of the most important renewable energy sources. The demand for solar panels has been continuously growing, both in the industrial electric sector and in the private sector. In both cases the analysis of the solar panel efficiency is extremely important in order to maximize the energy production. In order to have a more efficient photovoltaic system, the most accurate understanding of this system is required. However, in most of the cases the only information available in this matter is reduced, the experimental testing of the photovoltaic device being out of consideration, normally for budget reasons. Several methods, normally based on an equivalent circuit model, have been developed to extract the I-V curve of a photovoltaic device from the small amount of data provided by the manufacturer. The aim of this paper is to present a fast, easy, and accurate analytical method, developed to calculate the equivalent circuit parameters of a solar panel from the only data that manufacturers usually provide. The calculated circuit accurately reproduces the solar panel behavior, that is, the I-V curve. This fact being extremely important for practical reasons such as selecting the best solar panel in the market for a particular purpose, or maximize the energy extraction with MPPT (Maximum Peak Power Tracking) methods

Comprehensive Approach to Modeling and Simulation of Photovoltaic Arrays

This paper proposes a method of modeling and simulation of photovoltaic arrays. The main objective is to find the parameters of the nonlinear I-V equation by adjusting the curve at three points: open circuit, maximum power, and short circuit. Given these three points, which are provided by all commercial array datasheets, the method finds the best I-V equation for the single-diode photovoltaic (PV) model including the effect of the series and parallel resistances, and warranties that the maximum power of the model matches with the maximum power of the real array. With the parameters of the adjusted I-V equation, one can build a PV circuit model with any circuit simulator by using basic math blocks. The modeling method and the proposed circuit model are useful for power electronics designers who need a simple, fast, accurate, and easy-to-use modeling method for using in simulations of PV systems. In the first pages, the reader will find a tutorial on PV devices and will understand the parameters that compose the single-diode PV model. The modeling method is then introduced and presented in details. The model is validated with experimental data of commercial PV arrays.24417951198120

Micro-inverter for integrated grid-tie photovoltaic module using resonant controller

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Two-stage isolated converters for photovoltaic (PV) applications commonly employ a high-frequency transformer (HFT) on the DC-DC side, submitting the DC-AC inverter switches to high voltages and forcing the use of insulated-gate bipolar transistors instead of low-voltage and low-loss metal-oxide-semiconductor field-effect transistors. This paper shows the modeling, control and simulation of a single-phase full-bridge inverter with HFT that can be used as part of a two-stage converter with transformerless DC-DC side or as a single-stage converter (simple DC-AC inverter) for grid-connected PV applications. The inverter is modeled to obtain a small-signal transfer function used to design the P+Resonant current control regulator, whose main advantages are the simplicity for implementation in single-phase systems and zero steady state error with sinusoidal current. A high-frequency step-up transformer results in low-voltage switches and better efficiency compared with converters in which the transformer is used on the DC-DC side. Simulations and experimental results with a 200-W prototype are shown. Copyright (c) 2013 John Wiley & Sons, Ltd.245713722Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [10/15848-7, 08/07956-4, 10/50101-0

Voltage regulation of photovoltaic arrays: small-signal analysis and control design

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)This study deals with the regulation of the output voltage of photovoltaic (PV) arrays. As a case study, the DC-DC buck converter is used as an interface between the PV array and the load, but other types of converters can be used for the same purpose. The input voltage of the converter is controlled in order to regulate the operating point of the array. Besides reducing losses and stress because of the bandwidth-limited regulation of the converter duty cycle, controlling the converter input voltage reduces the settling time and avoids oscillation and overshoot, making easier the functioning of maximum power point tracking (MPPT) methods. The voltage regulation problem is addressed with a detailed analysis that starts with the modelling of the PV array and the converter. This analysis is followed by study, design, simulation and practical experiments of three closed-loop control strategies for the buck converter. Control stability and implementation considerations are presented.36869880Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Performance comparison of DC and AC controllers for a two-stage power converter in energy storage application

This paper presents a procedure for modelling and controlling a single-phase, two-stage, bidirectional DC-AC converter for application of energy storage system (ESS) in autonomous microgrids, in addition to experimental verification of its uninterruptible power supply (UPS) functionality. Average theory and frequency analysis are utilized to model the power converters and design the controllers in a generic fashion. Performance comparison of different controllers (type-2 and type-3 Venable compensators, Proportional Integral, Resonant-PI and multiple-RPI) is realised through simulations and tests. To tune the controllers, parameter values of crossover frequency and phase margin are adjusted by comparing simulation responses of the converters. A 5-kW ESS is evaluated through simulations during normal operation (grid-connected or stand-alone mode), as well as under transition events such as disconnection and recovery of the main grid. Besides that, a 100-W system was implemented, in which grid-connected mode was evaluated by measuring the power factor (about 0.998 in simulation and 0.993 in test at rated power), while stand-alone mode was evaluated by the total harmonic distortion of the output voltage (about 1.57% in simulation and 2.35% in test at rated power). The presented procedure can also be used to design higher power systems1644760CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPnão temnão tem2016/08645-9This work was supported by CNPq, CAPES, FAPESP (2016/08645-9), CPFL (ANEEL/PA3032), and BYD Energy Brazil (MCTIC-PADIS

Analytical modelling and analysis of thermal behavior for series resistance of solar cell

In this paper, the analysis of the nonlinear and complex modelling of a solar cell is addressed, to study its thermal behaviour. From literature it is well known that the output power of a solar cell monotonically decreases with the temperature; here, we investigate the specific expression based on derivation of current and power to simplify the equation model. Thus, applying the specific expression of the series resistance, we analyze the relation characteristics between the power and the temperature. Moreover, we aim to present a method to determine the specific theoretical expression of the series resistance with combination of parallel parasitic resistances. The analytical model equation is tested and compared with experimental results to add validity to the model

Effective in-laboratory test method for PV power generation with enhanced PV emulation accuracy

Photovoltaic (PV) systems require outdoor experiments to verify their functionality and reliability. However, outdoor experiments require complicated experimental set-ups including PV panels, power conversion circuits and controllers. In addition, the experimental data obtained from such systems can be easily affected by environmental conditions such as weather, temperature and season. Recently, PV emulation methods have been proposed that can emulate PV characteristics in the laboratory by connecting a DC supply to PV modules in parallel. However, the voltage characteristics of the conventional PV emulator are different from those of real PV panels, which degrades the accuracy of the PV emulator. This paper proposes an effective PV emulation method with accuracy improvements at the maximum power point of the PV panel, which is based on a simple circuit analysis. Using the proposed PV emulation method, the performance verification of a target PV system can be easily and accurately obtained. The proposed emulation method for PV power generation is experimentally verified by comparisons between it, the conventional emulation method and results obtained from outdoor experiments