Solar photovoltaic (PV) energy has witnessed double-digit growth in the past decade. The penetration of PV systems as distributed generators in low-voltage grids has also seen significant attention. In addition, the need for higher overall grid efficiency and reliability has boosted the interest in the microgrid concept. High-efficiency PV-based microgrids require maximum power point tracking (MPPT) controllers to maximize the harvested energy due to the nonlinearity in PV module characteristics. Perturb and observe (PO second, no steady-state oscillations around the MPP; and lastly, no need for predefined system-dependent constants, hence provides a generic design core. A design example is presented by experimental implementation of the proposed technique. Practical results for the implemented setup at different irradiance levels are illustrated to validate the proposed technique.

High-Performance Adaptive Perturb and Observe MPPT Technique for Photovoltaic-Based Microgrids

It has become imperative for the power and energy engineers to look out for the renewable energy sources such as sun, wind, geothermal, ocean and biomass as sustainable, cost-effective and environment friendly alternatives for conventional energy sources. However, the non-availability of these renewable energy resources all the time throughout the year has led to research in the area of hybrid renewable energy systems. In the past few years, a lot of research has taken place in the design, optimization, operation and control of the renewable hybrid energy systems. It is indeed evident that this area is still emerging and vast in scope. The main aim of this paper is to review the research on the unit sizing, optimization, energy management and modeling of the hybrid renewable energy system components. Developments in research on modeling of hybrid energy resources (PV systems), backup energy systems (Fuel Cell, Battery, Ultra-capacitor, Diesel Generator), power conditioning units (MPPT converters, Buck/Boost converters, Battery chargers) and techniques for energy flow management have been discussed in detail. In this paper, an attempt has been made to present a comprehensive review of the research in this area in the past one decade.

Hybrid renewable energy systems for power generation in stand-alone applications: A review

A new fuzzy-logic controller for maximum power point tracking of photovoltaic (PV) systems is proposed. PV modeling is discussed. Conventional hill-climbing maximum power-point tracker structures and features are investigated. The new controller improves the hill-climbing search method by fuzzifying the rules of such techniques and eliminates their drawbacks. Fuzzy-logic-based hill climbing offers fast and accurate converging to the maximum operating point during steady-state and varying weather conditions compared to conventional hill climbing. Simulation and experimentation results are provided to demonstrate the validity of the proposed fuzzy-logic-based controller.

Fuzzy-Logic-Control Approach of a Modified Hill-Climbing Method for Maximum Power Point in Microgrid Standalone Photovoltaic System

Simple, fast and accurate two-diode model for photovoltaic modules

In recent years there has been a growing attention towards use of solar energy. The main advantages of photovoltaic (PV) systems employed for harnessing solar energy are lack of greenhouse gas emission, low maintenance costs, fewer limitations with regard to site of installation and absence of mechanical noise arising from moving parts. However, PV systems suffer from relatively low conversion efficiency. Therefore, maximum power point tracking (MPPT) for the solar array is essential in a PV system. The nonlinear behavior of PV systems as well as variations of the maximum power point with solar irradiance level and temperature complicates the tracking of the maximum power point. A variety of MPPT methods have been proposed and implemented. This review paper introduces a classification scheme for MPPT methods based on three categories: offline, online and hybrid methods. This classification, which can provide a convenient reference for future work in PV power generation, is based on the manner in which the control signal is generated and the PV power system behavior as it approaches steady state conditions. Some of the methods from each class are simulated in Matlab/Simulink environment in order to compare their performance. Furthermore, different MPPT methods are discussed in terms of the dynamic response of the PV system to variations in temperature and irradiance, attainable efficiency, and implementation considerations.

Classification and comparison of maximum power point tracking techniques for photovoltaic system: A review

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.

Comprehensive Approach to Modeling and 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.

Modeling and circuit-based simulation of photovoltaic arrays

Voltage source inverter plays an important role in modern industry. Conventional voltage source inverter has a large electrolytic capacitor as energy store element in order to keep the dc link voltage constant. However, a large electrolytic capacitor increases the input current distortion. Replacing the large electrolytic capacitor by a small film capacitor the input current quality is improved but the output currents are distorted by low order harmonics. This paper proposes a simple current control method for a voltage source inverter without the use of a large electrolytic capacitor in the dc link in order to compensate the low order harmonics in the output currents. The proposed current control scheme employs just one PI regulator and since that the space vector modulation is used in this control the switching frequency of the converter is kept constant.

A control method for voltage source inverter without dc link capacitor

High step-up ratio converters for low-voltage high-current energy sources are nowadays the focus of an intensive research activity by the power electronics community, thanks to the increasing interest for renewable energy sources like those based on photovoltaic modules and fuel-cells. One interesting topology presented in literature is based on the combination of a boost section and a flyback one, featuring the possibility to boost the output voltage while keeping the switch voltage stress at a reasonable level. However, the basic integrated boost-flyback (IBF) topology suffers of parasitic oscillations caused by the transformer leakage inductances and the diode parasitic capacitance. These oscillations require a suitable dissipative clamp circuit to reduce the diode voltage stress, thus adversely affecting the overall converter efficiency. In this paper, a clamping diode is added to the original IBF topology that naturally clamp these parasitic oscillations, and make the converter operation more similar to that of the IBF converter with voltage multiplier. It is also shown that a resonance occurs that helps to increase the converter's voltage gain. Experimental results taken from a 300W rated prototype are included, showing a good agreement with the theoretical expectations.

Improved integrated boost-flyback high step-up converter

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.

Jonas Rafael Gazoli

Papers

Comprehensive Approach to Modeling and Simulation of Photovoltaic Arrays

Modeling and circuit-based simulation of photovoltaic arrays

A control method for voltage source inverter without dc link capacitor

Improved integrated boost-flyback high step-up converter

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