Optimal Operation of an Urban Microgrid Using Model Predictive Control Considering Power Quality Improvements

Abstract Microgrids have been widely applied to improve the energy quality parameters of a distribution system locally, in addition to ensuring the operation of the system in an isolated manner. The Model Predictive Control (MPC) is a great solution to guarantee the operation of the system considering forecasting models and also physical restrictions of the system, which ensure the optimal operation of the Microgrid. However, the construction of a control scheme following the objectives established in order to meet the connected and isolated operation of a Microgrid is still a challenge. This paper proposes the development of an MPC control scheme that assures optimal system operation in connected and islanded mode, improving power quality indexes, ensuring network requirements, and extending battery life cycle. The proposed control operation in the connected mode can attend to the needs of the Microgrid, reducing the impacts of peak demand and the intermittent variations in renewable generation, where a linear objective function is developed for this purpose. In the islanded mode, grid requirements are guaranteed through load shedding, considering improvements in continuity indicators. Forecasting models are implemented considering the MPC approach and a detailed network model is developed. Simulation results highlight the effectiveness of the proposed control strategy.

Optimal Dispatch and Technical and Economic Feasibility Analysis of Residential Microgrids Considering Demand Side Management

Abstract The electrical system is becoming more robust with the insertion of distributed energy resources (DERs) and the need for energy autonomy by consumers, given that the current scenario is a growth in demand for electric energy. This paper aims to apply a computational model capable of determining the optimal hourly allocation of controllable loads in residence, as well as studying the optimal dispatch of residential microgrids considering management on the demand side. In addition, this paper presents an economic feasibility analysis of residential microgrids considering distributed generation from wind and solar sources, distributed storage, electric vehicles, and residential controllable loads. Thus, it was possible to conclude that in residence, the insertion of distributed energy generation and storage elements can present a significant reduction in electric energy costs, which can be even greater if these elements are associated with optimized controllable load management.

Recent Research and Development of Microgrids in Parana

Abstract Microgrids (MGs) have increasingly attracted the attention of researchers, government officials, and electricity companies for the values and services they can add to the grid. They can operate independently as a single controllable unit in a coordinated way while connected or islanded, which make them suitable to integrate the growing amount of distributed energy resources (DERs) into the distribution network (DN). An active distribution network with high penetration of DERs could be redefined into a collection of microgrids in different layers, pooling their resources together to enhance the grid's performance in the sense of electricity as a service. However, enabling a microgrid-based power system infrastructure poses challenges concerning operation and control. In this paper, a comprehensive overview of research topics regarding microgrid operation are shown in a hierarchical or stratified manner, looking for a holistic vision of a microgrid-based distribution system. First, multi-objective optimization within one microgrid is formulated aiming to minimize costs and maximize battery life is presented. Second, the interaction among MGs, DERs and the DN was modeled using the OPF technique to represent the operation of the grid as a whole. Following, a methodology for collaborative optimization of multiple MGs operating together is presented and at last a theoretical framework for MG operation through decentralized energy markets is discussed. As a result, this paper aims to contribute to a broad vision of the distribution system based on microgrid operation in all its levels.

A Computational Framework for Daily Power Flow Analysis Considering Photovoltaic Distributed Generation

Abstract In Brazil, the demand for the acquisition and installation of photovoltaic systems has grown exponentially and, with that, the importance of studies considering their effects on the distribution grids power flow also grows. Due to the intermittent nature of photovoltaic generation, it is important to approach the analysis in a discrete way, taking into account the changes in the power injections during the studied period. Thus, this article presents the daily analysis of the effects of photovoltaic generation on the distribution system through the computational implementation of a discretized power flow routine. The implemented routine can also analyze the effects of other distributed generations on distribution grids, whether those grids are radial or not. The study results show positive impacts on the voltage quality obtained by the photovoltaic systems insertion, for a well-known distribution test system.

Computational algorithm for stability analysis of distribution networks with distributed generation

Abstract With the insertion of distributed generation in distribution networks, security analysis becomes crucial, in islanded operation or when the system is connected to the grid. Dynamic stability analyses are necessary in order to achieve minimum levels of security and reliability. Such analyses are obtained through the solution of the algebraic-differential set of equations that model the distribution grid and their generators, which requires numerical solution methods. Therefore, this paper presents a computational tool for transient stability and large disturbance frequency stability analysis, considering distribution systems with the insertion of biomass-fed distributed generation, which may, or may not, have speed regulation systems. The presented tool may be employed to assess assorted system indexes, such as the severity of disturbances, the quality of a given operating condition, in terms of voltage and frequency operating limits, and the response of both the system and the generators in face of the action of speed regulators.

Photovoltaic Cell Temperature Estimation for a Grid-Connect Photovoltaic Systems in Curitiba

Abstract The photovoltaic solar energy has been growing in installed capacity worldwide year by year, and Brazil has also been investing in this renewable source of energy generation. The conversion of light into electrical energy occurs in the photovoltaic cells, which are sensitive to the increase of the temperature. A considerable amount of the energy incident on the module is transformed into heat, rising its temperature and decreasing its efficiency. This study aims to estimate the temperature in photovoltaic cells (Tc) for polycrystalline silicon modules from a grid-connected photovoltaic systems through several equations proposed over the last decades by researchers. This estimation will occur in the municipality of Curitiba, using data from INMET's automatic station, located in the same city. The estimation was calculated hourly, throughout the day for one year. The validation of the estimated results was performed by measuring the cell temperature of a photovoltaic system installed in Curitiba, where it was observed that the equation proposed by Duffie and Beckman (2013) was the one that most approached to the measured value.

Technical Losses Reduction in Underground Reticulated Distribution Systems using Artificial Neural Networks and Smart Grid Features

ABSTRACT This work presents the methodology, development and testing of an autonomous system, based on Artificial Neural Networks (ANN), for the reduction of technical losses in reticulated underground systems through the optimal control of the capacitor banks (CBs) present in the grid. The proposed methodology includes Smart Grid features, including practical solutions for current transformers positioning in underground networks, collecting field measurements for the Distribution Operation Centre (DOC) and real-time control of field equipment (capacitors banks). The steps of the proposed methodology and the main aspects of the development of the system are also described, as well as the tests performed to prove the results and validate the system.

State-of-the-Art Impacts of Smart Grid in the Power Systems Operation and Expansion Planning

ABSTRACT In this article, a state-of-the-art review on the impacts of Smart Grid in the operation and planning of the expansion of the Electric Power System is presented. The concept of Smart Grid is increasingly integrated in conventional networks, and the impact that this new technology generates on operation and planning must be investigated. Thus, in this article a survey of the main scientific publications was made with the purpose of determining the impacts and methodologies most used in this analysis. Efforts to analyze impacts are large because of the high degree of uncertainty of this new technology added to the problem. After the bibliographic survey, it was concluded that Robust Optimization and Genetic Algorithms are methodologies that are effective in problems of this nature and are the most adopted methods.

Power Flow Analysis and Self-recovery of Electrical Energy Distribution Network Using Artificial Neural Networks

ABSTRACT A computational model for self-recovery of electricity distribution network was developed to simulate it, emulated by the IEEE 123 node model. The electrical system considered has automatic switches capable of identifying a momentary failure in the line and finding the best reconfiguration for its reclosing. An artificial neural network (ANN), backpropagation, was used to classify the type of failure and determine the best reconfiguration of the distribution network. Initially, five power failure scenarios were simulated in certain different parts of the power grid, and power flow analysis via OpenDSS was performed. Next, the most suitable switching was observed within the shortest time interval to restore the power supply. With the purpose of better visualization to identify the reclosing, an implementation was carried out via ELIPSE SCADA. In this way, it is possible to identify the faulted segment in order to isolate it, leaving the smallest number of consumers without power supply in shortest possible time. With the results of the simulations, tests and analyzes were performed to verify their robustness and speed, in the expectation that the model developed be faster than an experienced Operating Distribution Center.

Characterization of grid-connected photovoltaic systems in Curitiba, Brazil

ABSTRACT In the search for new options for the establishment of the energy matrix of Brazil, the Grid-Connected Photovoltaic Systems (GCPVS) are configured as an alternative to urban centers, because they allow the power generation at distributed mode, that is, generate energy at the place where it will be consumed and inject the surplus energy into the network. Faced with the prospect of installing Grid-Connected Photovoltaic System, the objective of this research is to characterize this type of photovoltaic system installed in Curitiba, State of Paraná, Brazil. This paper highlights that up to July 2017 the State of Paraná has 1031 GCPVS in operation, which corresponds to 6,6MW, while Curitiba has 204 GCPVS that represents 997.4 kW in operation, 82% of which are installed in residences. In addition, the study of a sample of 41 GCPVSs installed in Curitiba shows that 98% of these systems use multicrystalline modules, 75% use single phase inverters and 95% of these use inverters transformerless. This shows that the losses in the conversion process are reduced and the equipment is more compact using better technology than the inverters with transformer. Therefore, the main trend of photovoltaic energy market is to use transformerless inverters.

Energy Analysis in Supermarkets

ABSTRACT This study shows, through several analyses, ways to reduce costs with electric power in supermarkets. For this purpose, one of those establishments was visited and several data were collected for subsequent analysis. The results have shown that the combinations of several actions of energy efficiency can be applied when the objective is the reduction of costs with electric power.

Effects of the Photovoltaic Distributed Generation on Electricity Distribution System Voltage - Updated Review

ABSTRACT Concerns about the environment and a growing demand for electricity have led to the intensive search for renewable energy sources. Photovoltaic solar energy, in the form of distributed generation, has shown a very high growth rate to an extent that in some regions it will be adopted on a large scale, thus being responsible for the supply of a significant portion of the load of this region. Some factors have favored the adoption of distributed generation: the drop in the price of solar panels and inverters, as well as its easy installation and maintenance. However, the large-scale adoption of solar distributed generation brings new challenges to the power distribution system. Network voltage control is an example. In conventional systems, voltage control is a properly addressed problem, but in networks with the presence of distributed generation, where at certain times of the day reverse energy flows can be observed, more detailed studies on voltage behavior are necessary concerning the power quality. This article makes an analysis of relevant studies on the effects that the insertion of photovoltaic distributed generation can cause in the voltage of the electric power distribution system under the optics of two phenomena: the fluctuation and the voltage ripple.

Comparison of the Performance of the Grid- Connected Photovoltaic System Installed In the Brazilian Cities: Blumenau - SC and Curitiba- PR

ABSTRACT This is a study that contemplates the analysis of the main characteristics of 8 grid connected photovoltaic systems (GCPVS), 3 of which are located in the city of Curitiba-PR and 5 located in the city of Blumenau-SC. Data were collected on irradiation in the horizontal plane, generated energy and rainfall, being the first two to calculate the merit indexes, such as Yield, Performance Ratio and Capacity Factor - of those on grid connected Photovoltaic systems.

Mapping and Characterization of the Grid-connected Photovoltaic Systems in the City of Curitiba: Preliminary Results

ABSTRACT This work presents the mapping of grid-connected photovoltaic systems supported by the Normative Resolution (NR) of the National Agency of Electric Energy (ANEEL) Nº 482/2012 in the city of Curitiba. Firstly, a brief introduction was made justifying the reasons that led to the development of this study, followed by the explanation about the methodology, procedures and criteria adopted in the study. A general mapping of all on-grid photovoltaic systems supported by NR Nº 482/2012 installed in the city of Curitiba, identified by class, is presented, indicating how the urban distribution of these photovoltaic systems occurs, and it is possible to observe in which regions the highest prevalence of installations occurs. From this, the general characterization of these photovoltaic systems is performed, classifying them by class, number of installed systems, power, number of modules, total occupied area, average power of modules and average efficiency of photovoltaic systems. Considerations are also raised regarding the reliability of the Database of Distributed Generation Consumer Units made available by ANEEL.

Analysis of the Operation of Photovoltaic Systems Installed at Federal University of Technology - Paraná in Curitiba

ABSTRACT The Federal University of Technology - Paraná (UTFPR), Campus Curitiba, has a Grid-Connected Photovoltaic System (GCPVS) of 2.1 kWp in the Green Office (GO), which has been in operation since December 2011, and until September 2017 generated little more than 13.64 MWh and a GCPVS of 10.2 kWp, in operation since February 2016. The photovoltaic panel of the 2.1 kWp system was set up following the inclination of the roof of the building, which does not give its maximum performance. On the other hand, the panel of the 10.2 kWp system in Neoville was installed in optimum conditions, that is, oriented to the north and with slope equal to the latitude of Curitiba and, up tol September 2017 generated more than 20.65 MWh. This paper presents the monitoring of the electric energy generated by the systems and also a history of the merit indexes of the GCPVS, which are: Productivity (Yield); Performance Ratio; and Capacity Factor. These indexes allow to evaluate the performance of the GCPVS and make a comparison between them. Finally, the photovoltaic generation of both GCPVS proved to be a sustainable and effective form of distributed generation of electric energy in the urban environment.

The Photovoltaic Generation and its Energy Contribution and Demand Shifting at the Center Headquarters of the Federal University of Technology - Paraná - Campus Curitiba

ABSTRACT Distributed photovoltaic (PV) generation is characterized by the application of several small power plants in urban centers. This form of energy deserves special mention due to the possibility of installation in existing areas such as roofs and facades. Thus, the implementation of these systems represents positive modifications of the urban scenario, with the adhesion of PV modules, presenting much smaller social and environmental impacts than that of large conventional plants. In this sense, this study aims at analyzing the demand and consumption curves of the Center headquarters buildings of Federal University of Technology - Paraná (UTFPR) in Curitiba, by applying the COPEL's CAS Hemera platform, in order to determine the potential for implementation of grid-connected photovoltaic systems in this premise, because they allow the cost reductions in electric power. The first UTFPR's grid-connected photovoltaic system was introduced in December 2011, at the Center's headquarters, in one of the blocks of the university, which by the end of 2016 generated a total of 11.67 MWh of electricity. This paper proposes an expansion scenario for the existing grid-connected photovoltaic system, using the available coverage showing the shifting or reduction of energy demand peaks and the energy contribution to UTFPR's Center headquarters.

Protection of Grid Connected Photovoltaic Systems (GCPVS)

ABSTRACT Installations of photovoltaic systems connected or not to the electrical network have become increasingly popular, but it is often carried out by unqualified people using low quality components. The present study aims to describe the methodology adopted for the protection of grid connected photovoltaic systems (GCPVS) and the implications caused by their lack. Photovoltaic modules are typically installed in galvanized, painted, stainless aluminum or steel structures, which must be connected to a common ground, as these structures and any other components of the system could be energized by the photovoltaic array and may cause serious injuries or even death during routine maintenance, these fatalities can still result in ramifications for the entire industry, with millions of dollars in liability (for death or injury), negative publicity for GCPVS, and increased complications in obtaining licenses. Also, its components must be of good quality and the systems of protection must be well dimensioned and correctly installed, in order to avoid fire and electric damages, with reduction of possible damages in cases of short circuits.

Acidentes de trabalho e os religadores automáticos no setor elétrico: para além das causas imediatas / Work accidents and automatic circuit reclosers in the electricity sector: beyond the immediate causes / Accidentes de trabajo y reconectadores automáticos en el sector eléctrico: más allá de las causas inmediatas

Resumo: O setor elétrico brasileiro registra elevados índices de mortalidade por acidentes de trabalho que vêm sendo associados à terceirização, introduzida como forma de rebaixamento de custos. Para diminuir o tempo de interrupção do fornecimento de energia aos consumidores, o setor adotou, como solução tecnológica, o religador automático. Essa medida apresenta características perversas para os trabalhadores de manutenção. O objetivo deste estudo é analisar origens e consequências de acidentes de trabalho em sistemas elétricos dotados de religador automático utilizando o Modelo de Análise e Prevenção de Acidentes (MAPA). O MAPA foi usado na investigação de dois acidentes de trabalho visando a explorar as origens organizacionais dos eventos. Caso 1 - ao trocar linha secundária desenergizada, um trabalhador foi atingido por cabo primário energizado (13,8kV). O sistema foi religado três vezes, agravando as lesões (amputação de membro inferior). Caso 2 - acidente de trabalho fatal ocorrido durante instalação de cruzeta nova, em linha energizada, parcialmente isolada. A extremidade de uma mão francesa metálica encostou na linha secundária energizada e eletrocutou o operador de manutenção. O componente desligador do religador automático não funcionou. As análises contribuem para desvelar como a lógica de gestão de negócios pode participar nas origens de acidentes de trabalho via falhas da gestão de manutenção, da gestão de força de trabalho de terceiras e, em especial, da gestão de segurança em sistemas dotados de religadores. As decisões pela automação para garantir a distribuição de energia não podem negligenciar os riscos aos trabalhadores da rede elétrica e, tampouco, deixar de reconhecer a importância do controle sobre as condições de segurança.

Abstract: The Brazilian electricity sector has recorded high work-related mortality rates that have been associated with outsourcing, used to cut costs. In order to decrease the power outage time for consumers, the industry adopted the automatic circuit recloser as the technical solution. The device has hazardous implications for maintenance workers. The aim of this study was to analyze the origins and consequences of work accidents in power systems with automatic circuit recloser, using the Accident Analysis and Prevention (AAP) model. The AAP model was used to investigate two work accidents, aimed to explore the events' organizational origins. Case 1 - when changing a deenergized secondary line, a worker received a shock from the energized primary cable (13.8kV). The system reclosed three times, causing severe injury to the worker (amputation of a lower limb). Case 2 - a fatal work accident occurred during installation of a new crosshead on a partially insulated energized line. The tip of a metal cross arm section strap touched the energized secondary line and electrocuted the maintenance operator. The circuit breaker component of the automatic circuit recloser failed. The analyses revealed how business management logic can participate in the root causes of work accidents through failures in maintenance management, outsourced workforce management, and especially safety management in systems with reclosers. Decisions to adopt automation to guarantee power distribution should not overlook the risks to workers in overhead power lines or fail to acknowledge the importance of ensuring safe conditions.

Resumen: El sector eléctrico brasileño registra elevados índices de mortalidad por accidentes de trabajo, que están siendo asociados a la tercerización, introducida como forma de reducción de costes. Para disminuir el tiempo de interrupción de la energía a los consumidores, el sector adoptó como solución tecnológica, el reconectador automático. Esta medida presenta características perversas para los trabajadores del sector de mantenimiento. El objetivo de este estudio es analizar los orígenes y consecuencias de los accidentes de trabajo en sistemas eléctricos dotados de reconectador automático, utilizando el Modelo de Análisis y Prevención de Accidentes (MAPA). El MAPA se usó en la investigación de dos accidentes de trabajo, con el objetivo de explorar las causas organizativas de los eventos. Caso 1 - al cambiar la línea secundaria sin energía, un trabajador fue alcanzado por un cable primario con energía (13,8kV). El sistema se reconectó tres veces, agravando las lesiones (amputación de miembro inferior). Caso 2 - accidente de trabajo fatal ocurrido durante la instalación de una cruceta nueva, en una línea con energía, parcialmente aislada. La extremidad de una cruceta metálica cayó en la línea secundaria con energía y electrocutó al obrero de mantenimiento. El componente que desconectaba el reconectador automático no funcionó. Los análisis contribuyen a desvelar cómo la lógica de gestión de negocios puede ser partícipe en las causas de accidentes de trabajo, vía fallos en la gestión del mantenimiento, de la gestión de fuerza de trabajo de terceras personas y, en especial, de la gestión de seguridad en sistemas dotados de reconectadores. Las decisiones de la automatización para garantizar la distribución de energía no pueden obviar los riesgos para los trabajadores de la red eléctrica y tampoco dejar de reconocer la importancia del control sobre las condiciones de seguridad.

Medial Lemniscus Tract Lesion After High Voltage Electrical Injury: A Case Report

We present the case of a 33-year-old man who experienced a 10,000-V electrical shock when working with electrical wiring. He suffered third-degree burns on his scalp at the right occiput (entry wound) and on his left arm (exit would), and a second-degree burn on his left foot (exit wound). He presented with severe spasticity of both lower extremities, motor weakness with a Medical Research Council grade of 3, and sensory impairments below thoracic level 11 that included an inability to sense light touch and defects in proprioception. Initial magnetic resonance imaging (MRI) scans of his spine and brain showed no definite abnormalities. However, tractography obtained by diffusion tensor imaging of the brain showed absence of the right medial lemniscus tract. A cervical MRI scan 1 month later showed spinal cord swelling from cervical 1-5 levels, and signal changes in the lateral and posterior white matter in the axial view. After 6 months of rehabilitation, he recovered almost normal degree of motor function in his lower extremities and disappearance of spasticity. However, since the sensory impairments persisted, especially defects in proprioception, he was unable to walk independently.

Manual de buenas prácticas: industria eléctrica / Good practice handbook: electrical safety

El presente manual propone una guía de buenas prácticas para la prevención de riesgos del trabajo, protección y promoción de la salud, destinada a todos los actores sociales del sector eléctrico. Es una herramienta útil para el desarrollo de políticas preventivas en los ámbitos laborales y un soporte de capacitación permanente para los trabajadores. Fue elaborado en el marco de los Programas Nacionales de Prevención por rama de actividad (PRONAPRE) de la SRT y es fruto del debate y el consenso de la Comisión de Trabajo Cuatripartita de la industria eléctrica en donde participaron activamente la Superintendencia de Riesgos del Trabajo, las empresas del sector a través de sus cámaras, las organizaciones sindicales y las aseguradoras de riesgos del trabajo