Jonas Rafael Gazoli

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 data sheets, 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.

Modeling and circuit-based simulation of photovoltaic arrays

This paper presents an easy and accurate method of modeling photovoltaic arrays. The method is used to obtain the parameters of the array model using information from the datasheet. The photovoltaic array model can be simulated with any circuit simulator. The equations of the model are presented in details and the model is validated with experimental data. Finally, simulation examples are presented. This paper is useful for power electronics designers and researchers who need an effective and straightforward way to model and simulate photovoltaic arrays.

A Simple Current Control for Matrix Converter

As the matrix converter performs electric energy direct transfer from the input to the output, the distortion and the unbalance of the input voltages affects directly the output of the matrix converter. This paper presents a new and simple current control for matrix converter based on the fact that if the magnitude of the output current space vector is constant, the output currents are sinusoidal and balanced. With this current control, it is possible to compensate the output of the matrix converter under unbalanced and distorted input voltage conditions without the need of symmetrical components decomposition of the input voltage or reference frame conversions. So it is not necessary heavy computation capability and the hardware implementation is very simple. The proposed current control scheme employs only one PI regulator and since that the space vector modulation is applied in this control, the switching frequency of the converter is kept constant

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

Two-stage isolated converters for photovoltaic (PV) applications commonly employ a high-frequency transformer on the DC-DC side, submitting the DC-AC inverter switches to high voltages and forcing the use of IGBTs instead of low-voltage and low-loss MOSFETs. This paper shows the modeling, control and simulation of a single-phase full-bridge inverter with high-frequency transformer (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 in order to obtain a small-signal transfer function used to design the P+Resonant current control regulator. A high-frequency step-up transformer results in reduced 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.

Resonant (P+RES) controller applied to voltage source inverter with minimum DC link capacitor

Voltage source inverters use large electrolytic capacitors in order to decouple the energy between the utility and the load, keeping the DC link voltage constant. Decreasing the capacitance reduces the distortion in the inverter input current but this also affects the load with low-order harmonics and generate disturbances at the input voltage. This paper applies the P+RES controller to solve the challenge of regulating the output current by means of controlling the magnitude of the current space vector, keeping it constant thus rejecting harmonic disturbances that would otherwise propagate to the load. This work presents a discussion of the switching and control strategy.

Comparative analysis of current and voltage-controlled photovoltaic Maximum Power Point tracking

Maximum Power Point tracking (MPPT) in photovoltaic (PV) systems may be achieved by controlling either the voltage or current of the PV device. There is no consensus in the technical literature about how is the best choice. This paper provides a comparative analysis performance among current and voltage control using two different MPPT strategies: the perturb and observe (P&O) and the incremental conductance techniques.

Analysis and simulationof the P&O MPPT algorithm using alinearized PV array model

This paper shows that the performance of the perturb and observe (P&O) maximum power point tracking (MPPT) algorithm is improved when the electronic converter is correctly controlled. A linearized photovoltaic (PV) array model is used to obtain the transfer function of the electronic converter and to design a voltage compensator for the converter input voltage. A buck converter is used in this work.

Multifuctional Control Strategy For Photovoltaic Distributed Generation Systems

This paper deals with a multi task control strategy for photovoltaic distributed generation inverters. Such strategy simultaneously allows the systems to inject the available energy on the primary side (usually DC), as well as to work as a voltage drop compensator or an active power filter, mitigating load current disturbances and improving power quality at the point of common coupling. The main difference among the proposed methodology from others in literature is that most of the proposed control loops are based on the Conservative Power Theory. It provides decoupled power and current references for the inverter control, offering a very flexible, selective and powerful strategy for the control system. Moreover, the proposed multifunctional controller also allows the system’s operation in island or grid-connected mode. Simulation and experimental results will be deArtigo submetido em 08/03/2013. Revisado em 16/07/2013. Aceito para publicação em 16/07/2013, por recomendação do Editor Henrique A. C. Braga. picted in order to validate some of the possible functionalities of the proposed scheme control.

Analysis of ensemble models in the medium term hydropower scheduling

The medium term hydropower scheduling (MTHS) problem involves an attempt to determine, for each time stage of the planning period, the amount of generation at each hydro plant which will maximize the expected future benefits throughout the planning period, while respecting plant operational constraints. Besides, it is important to emphasize that this decision-making has been done based mainly on inflow earliness knowledge. To perform the forecast of a determinate basin, it is possible to use some intelligent computational approaches. In this paper one considers the Dynamic Programming (DP) with the inflows given by their average values, thus turning the problem into a deterministic one which the solution can be obtained by deterministic DP (DDP). The performance of the DDP technique in the MTHS problem was assessed by simulation using the ensemble prediction models. Features and sensitivities of these models are discussed.

Um controlador de corrente de carga para o conversor em matriz trifásico para trifásico e para o inversor de frequência sem capacitor do elo de corrente contínua

Com o avanco da tecnologia dos dispositivos semicondutores de potencia os inversores de frequencia atuam de forma importante em toda industria. O inversor de frequencia convencional contem elementos armazenadores de energia no seu elo de corrente continua. Estes elementos armazenadores de energia sao capacitores eletroliticos e possibilitam manter a tensao do elo de corrente continua constante. Entretanto, quanto maior sua capacitância maior e a distorcao da corrente de entrada. Com a substituicao do banco de capacitores eletroliticos por um capacitor de filme, diminui-se a distorcao nas correntes de entrada, porem distorcoes indesejadas aparecem na tensao do elo de corrente continua e tambem nas correntes de saida. Estas distorcoes sao compostas por componentes harmonicas de baixas frequencias. O conversor em matriz trifasico-trifasico por sua vez, possibilita a transferencia direta de energia da entrada (rede) diretamente para a saida (carga) sem a necessidade de elementos armazenadores de energia como acontece no inversor de frequencia. Entretando o desbalanceamento das tensoes da entrada afetam diretamente a forma de onda das tensoes da saida. Dessa maneira, este trabalho propoe um metodo de controle de corrente do conversor em matriz e do inversor de frequencia sem banco de capacitores do elo de corrente continua com objetivo de compensar o desbalanceamento das tensoes de saida do conversor em matriz e compensar tambem as componentes harmonicas de baixa frequencia que aparecem nas correntes de saida do inversor de frequencia. O metodo proposto utiliza um controlador do tipo PI e modulacao por vetores espaciais para que a frequencia de acionamento das chaves dos conversores seja constante.