The need of subsidy for the implementation of photovoltaic solar energy as supporting of decentralized electrical power generation in Brazil

The growing demand for electrical power and the limited capital invested to provide this power is forcing countries like Brazil to search for new alternatives for electrical power generation. The purpose of this paper is to present a technical and economic study on a 15 kW solar plant installed in an isolated community, highlighting the importance of the need for financial subsidy from the government. It evaluates the importance of parameters such as the annual interest rate, specific investment, the marginal cost of expanding the electrical power supply and the government subsidy on amortization time of capital invested. © 2012 Elsevier Ltd All rights reserved.

Time-series-based maximization of distributed wind power generation integration

Energy policies and technological progress in the development of wind turbines have made wind power the fastest growing renewable power source worldwide. The inherent variability of this resource requires special attention when analyzing the impacts of high penetration on the distribution network. A time-series steady-state analysis is proposed that assesses technical issues such as energy export, losses, and short-circuit levels. A multiobjective programming approach based on the nondominated sorting genetic algorithm (NSGA) is applied in order to find configurations that maximize the integration of distributed wind power generation (DWPG) while satisfying voltage and thermal limits. The approach has been applied to a medium voltage distribution network considering hourly demand and wind profiles for part of the U.K. The Pareto optimal solutions obtained highlight the drawbacks of using a single demand and generation scenario, and indicate the importance of appropriate substation voltage settings for maximizing the connection of MPG.

Discrete-time sliding mode control of input-delay systems applied on a power generation system

This paper presents two discrete sliding mode control (SMC) design. The first one is a discrete-time SMC design that doesn't take into account the time-delay. The second one is a discrete-time SMC design, which takes in consideration the time-delay. The proposed techniques aim at the accomplishment simplicity and robustness for an uncertainty class. Simulations results are shown and the effectiveness of the used techniques is analyzed. © 2006 IEEE.

Probabilistic analysis of the distributed power generation in weakly meshed distribution systems

This paper presents an approach for probabilistic analysis of unbalanced three-phase weakly meshed distribution systems considering uncertainty in load demand. In order to achieve high computational efficiency this approach uses both an efficient method for probabilistic analysis and a radial power flow. The probabilistic approach used is the well-known Two-Point Estimate Method. Meanwhile, the compensation-based radial power flow is used in order to extract benefits from the topological characteristics of the distribution systems. The generation model proposed allows modeling either PQ or PV bus on the connection point between the network and the distributed generator. In addition allows control of the generator operating conditions, such as the field current and the power delivery at terminals. Results on test with IEEE 37 bus system is given to illustrate the operation and effectiveness of the proposed approach. A Monte Carlo Simulations method is used to validate the results. © 2011 IEEE.

Thermodynamic analysis and comparison of downdraft gasifiers integrated with gas turbine, spark and compression ignition engines for distributed power generation

The objective of the present article is to assess and compare the performance of electricity generation systems integrated with downdraft biomass gasifiers for distributed power generation. A model for estimating the electric power generation of internal combustion engines and gas turbines powered by syngas was developed. First, the model determines the syngas composition and the lower heating value; and second, these data are used to evaluate power generation in Otto, Diesel, and Brayton cycles. Four synthesis gas compositions were tested for gasification with: air; pure oxygen; 60% oxygen with 40% steam; and 60% air with 40% steam. The results show a maximum power ratio of 0.567 kWh/Nm(3) for the gas turbine system, 0.647 kWh/Nm(3) for the compression ignition engine, and 0.775 kWh/Nm(3) for the spark-ignition engine while running on synthesis gas which was produced using pure oxygen as gasification agent. When these three systems run on synthesis gas produced using atmospheric air as gasification agent, the maximum power ratios were 0.274 kWh/Nm(3) for the gas turbine system, 0.302 kWh/Nm(3) for CIE, and 0.282 kWh/Nm(3) for SIE. The relationship between power output and synthesis gas flow variations is presented as is the dependence of efficiency on compression ratios. Since the maximum attainable power ratio of CIE is higher than that of SIE for gasification with air, more research should be performed on utilization of synthesis gas in CIE. (C) 2014 Elsevier Ltd. All rights reserved.

Placement and sizing evaluation of distributed generation in electric power systems

This paper presents a methodology for the placement and sizing evaluation of distributed generation (DG) in electric power systems. The candidate locations for DG placement are identified on the bases of Locational Marginal Prices (LMP's) obtained from an optimal power flow solution. The problem is formulated for two different objectives: social welfare maximization and profit maximization. For each DG unit an optimal placement is identified for each of the objectives.

Distributed generation modelling for unbalanced three-phase power flow calculations in smart grids

Distributed Generators (DG) are generally modeled as PQ or PV buses in power flow studies. But in order to integrate DG units into the distribution systems and control the reactive power injection it is necessary to know the operation mode and the type of connection to the system. This paper presents a single-phase and a three-phase mathematical model to integrate DG in power flow calculations in distribution systems, especially suited for Smart Grid calculations. If the DG is in PV mode, each step of the power flow algorithm calculates the reactive power injection from the DG to the system to keep the voltage in the bus in a predefined level, if the DG is in PQ mode, the power injection is considered as a negative load. The method is tested on two well known test system, presenting single-phase results on 85 bus system, and three-phase results in the IEEE 34 bus test system. © 2011 IEEE.

Evaluation of integrated inverter topologies for low power PV systems

This work presents the stage integration in power electronics converters as a suitable solution for solar photovoltaic inverters. The rated voltages available in Photovoltaic (PV) modules have usually low values for applications such as regulated output voltages in stand-alone or grid-connected configurations. In these cases, a boost stage or a transformer will be necessary. Transformers have low efficiencies, heavy weights and have been used only when galvanic isolation is mandatory. Furthermore, high-frequency transformers increase the converter complexity. Therefore, the most usual topologies use a boost stage and one inverter stage cascaded. However, the complexity, size, weight, cost and lifetime might be improved considering the integration of both stages. These are the expected features to turn attractive this kind of integrated structures. Therefore, some integrated converters are analyzed and compared in this paper in order to support future evaluations and trends for low power single-phase inverters for PV systems. © 2011 IEEE.

Design and development of a low-cost solar tracker

To become competitive, ultimately, photovoltaics should have its costs reduced and use photovoltaic systems of greater efficiency. The main steps in this direction are the use of new materials, the improvement in the manufacture of modules and the adoption of techniques of maximum power point tracking and of solar tracking. This article aims at presenting the project and development of an azimuth and elevation solar tracker, based on a new conception of the positioning sensor, composed of an array of four photoresistors. The two direct current motors that operate in the vertical and horizontal axes are controlled by a proportional-integral microcontroller. The conditions of the project were low cost, small energy consumption and versatility. The microcontroller can also incorporate a maximum power point tracking algorithm. The performance of solar tracker prototype in the initial phase of field tests can be considered appropriate. © Institution of Engineers Australia, 2013.

Desenvolvimento de um modelo fuzzy para otimização da energia gerada por um sistema híbrido (solar-fotovoltaico e eólico)

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Analise de desempenho de um sistema híbrido de geração de energia solar-eólico-diesel considerando variações probabilísticas da carga e dos recursos renováveis

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise e modelagem geométrica da potência gerada por um sistema híbrido solar fotovoltaico eólico

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Adoção da energia solar fotovoltaica em hospitais: revisando a literatura e algumas experiências internacionais

The sun has an extremely important role in the existence of human beings, and Brazil has a privileged geographical position to explore sunlight. The union of these two factors favors the use of solar cells for converting solar energy into electricity by photovoltaic technology: it is a great alternative energy source, especially for being a clean one, causing less damage to the environment. This paper addresses the photovoltaic technology with a focus on hospitals, through case studies found in international literature, because hospitals, even running all important services to society, have a potential for pollution capable of causing damage to human health and the environment that is around them. It is estimated that the Brazilian oil reserves are sufficient for twenty-two years. This makes the search for alternative sources for power generation a necessity.

Estudo sobre a utilização de energia solar no Brasil para uso residencial

Pós-graduação em Engenharia Elétrica - FEB

Geração de energia elétrica a partir da concentração solar

The current world's need for clean and renewable energy sources aligned with the strong Brazilian growth looking to diversify its electric power generation sources, highly dependent on hydropower and petroleum encourages the implementation of technologies that reach this growth with diversity and cleaning. The sun energy source is considered inexhaustible and can meet the demand for energy through thermo solar plants to generate electricity. Several technologies are being studied and developed in the world and they can be used to generate electricity from the solar concentration, but in Brazil its use is still not found commercially. It is therefore essential to understand these technologies and develop knowledge about them so they can be implemented in Brazil. This work brings an overview of the thermo solar generation in Brazil, showing the different technologies and a thermodynamic simulation of one of such technologies considering a hybrid plant with complementary generation biomass, aiming at the generation of 1 MW in the Brazilian Northeast