Power management and control strategies for efficient operation of a solar power dominated hybrid DC microgrid for remote power applications

In this paper, a hybrid DC microgrid consisting of a diesel generator with a rectifier, a solar photovoltaic (PV) system, and a battery energy storage system is presented in relation to an effective power management strategy and different control techniques are adopted to power electronic interfaces. The solar PV and battery energy storage systems are considered as the main sources of energy sources that supply the load demand on a daily basis whereas the diesel generator is used as a backup for the emergency operation of the microgrid. All system components are connected to a common DC bus through an appropriate power electronics devices (e.g., rectifier systems, DC/DC converter). Also a detailed sizing philosophy of all components along with the energy management strategy is proposed. Energy distribution pattern of each individual component has been conducted based on the monthly basis along with a power management algorithm. The power delivered by the solar PV system and diesel generator is controlled via DC-DC converterand excitation controllers which are designed based on a linearquadratic regulator (LQR) technique as as proportional integral (PI)controllers. The component level power distribution is investigatedusing these controllers under fluctuating load and solar irradiationconditions and comparative results are presented.

2016 Road Use Tax Fund (RUTF) Study

A key component of Iowa’s transportation system is the public roadway system owned and maintained by the state, cities and counties. In order to regularly evaluate the conditions of Iowa’s public roadway infrastructure and assess the ability of existing revenues to meet the needs of the system, the Iowa Department of Transportation’s 2006 Road Use Tax Fund (RUTF) report to the legislature included a recommendation that a study be conducted every five years. That recommendation was included in legislation adopted in 2007 and signed into law. The law specifically requires the following (2016 Iowa Code Section 307.31):  “The department shall periodically review the current revenue levels of the road use tax fund and the sufficiency of those revenues for the projected construction and maintenance needs of city, county, and state governments in the future. The department shall submit a written report to the general assembly regarding its findings by December 31 every five years, beginning in 2011. The report may include recommendations concerning funding levels needed to support the future mobility and accessibility for users of Iowa's public road system.”  “The department shall evaluate alternative funding sources for road maintenance and construction and report to the general assembly at least every five years on the advantages and disadvantages and the viability of alternative funding mechanisms.” To comply with this requirement, the Iowa Department of Transportation (DOT) prepared a 2011 RUTF Study (www.iowadot.gov/pdf_files/RUTFStudy2011.pdf). This study relied heavily on the work of the Governor’s Transportation 2020 Citizen Advisory Commission (CAC), established by Governor Terry E. Branstad to assist the Iowa DOT as it assessed the condition of Iowa’s roadway system and evaluated current and future funding available to best address system needs. The 2011 RUTF Study ultimately led to the passage of Senate File 257 in the 2015 legislative session that was signed into law on February 25, 2015. The major component of this bill was the increase of the state fuel tax rate on March 1, 2015, in order to meet the critical need funding shortfall identified in the study. With the recent increase in the state fuel tax rate, jurisdictions across Iowa are now putting those additional funds into road and bridge construction projects. With one full construction season complete following the increase in funding, it is difficult to accurately assess the long-term impact on construction needs. Therefore, this 2016 RUTF Study focuses on the actions taken since the 2011 RUTF Study and on alternative funding mechanisms.

Modelo de competencias en TIC para el personal de una organización del sector eléctrico

La presente investigación pretendió incorporar el uso intensivo de TIC en los procedimientos establecidos y necesarios en los procesos de generación, distribución y control de la energía, lo que se expresa en un manual para el sistema de gestión humana de la organización analizada. La investigación partió de un levantamiento de un estado del arte, continuó con la realización de un análisis de actitudes y aptitudes de los colaboradores, basado en propuestas teóricas y mejores prácticas existentes del medio, y, por último, concluyó con un manual de gestión humana en el que se indican las competencias en los diferentes perfiles de la organización para el uso de TIC y su aplicación, con el propósito de alinearse con las perspectivas y objetivos de la organización analizada al tener como base la perdurabilidad y la competitividad de la misma.

Bidding and Optimization Strategies for Wind-PV Systems in Electricity Markets

The variability in non-dispatchable power generation raises important challenges to the integration of renewable energy sources into the electricity power grid. This paper provides the coordinated trading of wind and photovoltaic energy to mitigate risks due to the wind and solar power variability, electricity prices, and financial penalties arising out the generation shortfall and surplus. The problem of wind-photovoltaic coordinated trading is formulated as a linear programming problem. The goal is to obtain the optimal bidding strategy that maximizes the total profit. The wind-photovoltaic coordinated operation is modeled and compared with the uncoordinated operation. A comparison of the models and relevant conclusions are drawn from an illustrative case study of the Iberian day-ahead electricity market.

Perspetivas de utilização do potencial eólico em Timor-Leste

A exigência energética global está mais orientada para a utilização das fontes de Energias Renováveis (FERs), comprometendo e garantindo um desenvolvimento sustentável. Este trabalho tem como objetivo contribuir para o atingir das metas do PED 2011-2030, no que refere à utilização das FER, em particular do potencial eólico em Timor-Leste. Timor-Leste tem apresentado um grande interesse na política de aproveitamento de FER para alcançar a meta de longo prazo de PED 2030, comprometendo-se com o desenvolvimento sustentável através de ERs. Este trabalho pretende contribuir em particular com o estudo do aproveitamento de energia eólica. Com base no clima do vento de longo termo entre 2004 – 2012, da estação meteorológica (EM) de Díli e conjugando estes com os dados da campanha experimental de Martifer cedidos, de Dezembro 2008 - Novembro 2009, obteve-se o coeficiente de variabilidade (Cvariab.) inter-anual. Foi assim possível construir o mapa médio do vento de longo termo, com modelo atmosférico de mesoscala, numa resolução refinada de 3×3 km. Para a identificação dos locais mais favoráveis do vento, foi utilizado o modelo ArcGIS para georreferenciação do recurso. A filtragem das restrições e os constrangimentos do terreno permitiu construir o mapa do vento sustentável de Timor-Leste, por distritos, subdistritos, sucos, do enclave de Oecússi e a ilha de Atauro, o que conduziu à hierarquização de cinco zonas favoráveis (zona 1 - 5). A contribuição para o plano energético de Timor-Leste consiste em duas fases: - a 1ª fase o aproveitamento eólico em três PEs nas zonas monitorizadas (3 e 5) oriundo de dados cedidos pela Martifer, contabilizou-se um total de 424.694 MWh de produção de energia anual, tendo-se verificado o custo normalizado de energia (LCOE) no valor médio calculado de 0,046 €/kWh; - na 2ª fase a construção de acesso e o desenvolvimento de PEs nas zonas 1, 2 e 4 para o Cenário de Max-Renovável. Assim sendo, viabilizam a "Perspetiva de Utilização da Energia Eólica" no quadro do PED 2011 - 2030 de Timor-Leste, que viria reduzir o custo de produção de energia atual, e a emissão de CO2; Abstract: Prospects of Using Wind Energy in Timor-Leste The demand for global energy is more focused on the use of Reneweable Energy sources (REs), ensuring and committing itself to sustainable development. This study was prompted by the wish to contribute to the achievement the goals of the Strategic Development Plan (PED 2011-2030) regarding the use of REs, particularly the wind energy in Timor-Leste. Timor-Leste has presented a great interest in the use of renewable energy sources policy to achieve the long term goal of the PED 2030, committing to a sustainable development through renewable energy. This thesis intends to contribute in particular with the study of the use of wind energy. Based on the long term wind climate between 2004 and 2012 of the Díli weather station and combining these data with the Martifer campaign experimental data of December 2008 - November 2009, the interannual variation coefficient (Cv) was obtained. Thus, it was possible to build the map of long term average wind with atmospheric mesoscale model in a refined resolution of 3×3 km. The ArcGIS model was used for the identification of the most favorable locations of the wind for its georeferencing. The constraining of filtering and the constraints of the terrain allowed to construe the sustainable wind map of Timor-Leste in distritos, subdistritos, sucos, and also of the enclave of Oecussi and Atauro island, which led to the ranking of five favorable areas (zone 1-5) for an immediate experimental campaign of wind characterization and utilization of this resource in wind parks. The contribution to Timor-Leste's energy plan consists of two phases: - the first phase of three wind farms in zone (3 and 5) from data provided by Martifer, a total of 424,694 MWh, and levelyzed cost of electricity (LCOE) in the calculated average value of 0.046 €/kWh; - in the second phase the construction of access and development of wind farms in zones 1, 2 and 4 for the Max-Renewable Scenario. As such, they make possible the "Perspective of Wind Energy Use" in Timor Leste’s PED 2011 - 2030, which would reduce current energy production costs and CO2 emissions.

Armazenamento sazonal de energia solar térmica de baixa temperatura para climatização de edifícios

Face aos padrões atuais de vida, em que despendemos a maior parte do nosso tempo no interior de edifícios, com um nível de conforto que ninguém quer abdicar, urge o desenvolvimento de tecnologias de climatização sustentáveis. Devido a uma combinação única de fatores, casas de baixo consumo de energia (e também casas passivas) em Portugal, são particularmente adequadas de explorar as vantagens da energia solar térmica, especialmente quando combinado com armazenamento sazonal de energia. No entanto nenhum exemplo documentado existe de como esta sinergia pode ser explorada com sucesso em Portugal, ilustrando assim o modo em que a necessidade de aquecimento pode ser colmatada de uma forma sustentável sem o uso de combustíveis fósseis. A energia solar é uma excelente alternativa de fonte de energia para aquecimento de edifícios. Um principal fator que limita a sua aplicação é que é uma fonte de energia com uma disponibilidade média de variação cíclica. O uso de armazenamento sazonal de energia pode reduzir substancialmente o custo do sistema solar que é capaz de fornecer até 100% das necessidades energéticas dos edifícios. Estes sistemas são projetados para armazenar a energia solar durante o verão e reter o calor armazenado para posterior utilização durante o inverno; Abstract: SEASONAL SOLAR THERMAL ENERGY STORAGE FOR LOW TEMPERATURE HEATING BUILDINGS. Given the current standards of living, where we spent most of our time inside buildings, with a level of Comfort that no one wants to give up, urges the development of sustainable climate control technologies. Due to a unique combination of factors, low energy (and also passive) houses in Portugal are particularly well suited to exploiting the advantages of solar thermal energy especially when combined with seasonal energy storage. However no documented example there of how this synergy can be exploited successfully in Portugal, illustrating the way in which the need for heating can be addressed in a sustainable manner without the use of fossil fuels. Solar energy is an important alternative energy source for heating applications. One main factor that limits its application is that it is an energy source with an average availability of cyclical variation. The use of seasonal thermal energy storage can substantially reduce the cost of solar energy systems that can supply up to 100% of buildings energy needs. Such systems are designed to collect solar energy during the summer and retain the stored heat for use during the winter.

Bidding and Optimization Strategies for Wind-PV Systems in Electricity Markets Assisted by CPS

The variability in non-dispatchable power generation raises important challenges to the integration of renewable energy sources into the electricity power grid. This paper provides the coordinated trading of wind and photovoltaic energy assisted by a cyber-physical system for supporting management decisions to mitigate risks due to the wind and solar power variability, electricity prices, and financial penalties arising out the generation shortfall and surplus. The problem of wind-photovoltaic coordinated trading is formulated as a stochastic linear programming problem. The goal is to obtain the optimal bidding strategy that maximizes the total profit. The wind-photovoltaic coordinated operation is modelled and compared with the uncoordinated operation. A comparison of the models and relevant conclusions are drawn from an illustrative case study of the Iberian day-ahead electricity market.

Biodiesel production from waste cooking oil over sulfonated catalysts

Biodiesel production from waste cooking oil with methanol was carried out in the presence of poly(vinyl alcohol) with sulfonic acid groups (PVA-SO3H) and polystyrene with sulfonic acid groups (PS-SO3H), at 60°C. The PVA-SO3H catalyst showed higher catalytic activity than the PS-SO3H one. In order to optimize the reaction conditions, different parameters were studied. An increase of waste cooking oil conversion into fatty acid methyl esters with the amount of PVA-SO3H was observed. When the transesterification and esterification of WCO was carried out with ethanol over PVA-SO3H, at 60°C, a decrease of biodiesel production was also observed. The WCO conversion into fatty acid ethyl ester increased when the temperature was increased from 60 to 80°C. When different amounts of free fatty acids were added to the reaction mixture, a slight increase on the conversion was observed. The PVASO3H catalyst was reused and recycled with negligible loss in the activity.