Um algoritmo para estimação de estado em alimentadores de distribuição de energia elétrica com base no método da soma de potências

Most algorithms for state estimation based on the classical model are just adequate for use in transmission networks. Few algorithms were developed specifically for distribution systems, probably because of the little amount of data available in real time. Most overhead feeders possess just current and voltage measurements at the middle voltage bus-bar at the substation. In this way, classical algorithms are of difficult implementation, even considering off-line acquired data as pseudo-measurements. However, the necessity of automating the operation of distribution networks, mainly in regard to the selectivity of protection systems, as well to implement possibilities of load transfer maneuvers, is changing the network planning policy. In this way, some equipments incorporating telemetry and command modules have been installed in order to improve operational features, and so increasing the amount of measurement data available in real-time in the System Operation Center (SOC). This encourages the development of a state estimator model, involving real-time information and pseudo-measurements of loads, that are built from typical power factors and utilization factors (demand factors) of distribution transformers. This work reports about the development of a new state estimation method, specific for radial distribution systems. The main algorithm of the method is based on the power summation load flow. The estimation is carried out piecewise, section by section of the feeder, going from the substation to the terminal nodes. For each section, a measurement model is built, resulting in a nonlinear overdetermined equations set, whose solution is achieved by the Gaussian normal equation. The estimated variables of a section are used as pseudo-measurements for the next section. In general, a measurement set for a generic section consists of pseudo-measurements of power flows and nodal voltages obtained from the previous section or measurements in real-time, if they exist -, besides pseudomeasurements of injected powers for the power summations, whose functions are the load flow equations, assuming that the network can be represented by its single-phase equivalent. The great advantage of the algorithm is its simplicity and low computational effort. Moreover, the algorithm is very efficient, in regard to the accuracy of the estimated values. Besides the power summation state estimator, this work shows how other algorithms could be adapted to provide state estimation of middle voltage substations and networks, namely Schweppes method and an algorithm based on current proportionality, that is usually adopted for network planning tasks. Both estimators were implemented not only as alternatives for the proposed method, but also looking for getting results that give support for its validation. Once in most cases no power measurement is performed at beginning of the feeder and this is required for implementing the power summation estimations method, a new algorithm for estimating the network variables at the middle voltage bus-bar was also developed

Determinação de Chaveamento para Recomposição do Serviço em Redes de Distribuição de Energia Elétrica em Média Tensão Através de Métodos Baseado em Parâmetros de Sensibilidade

The reconfiguration of a distribution network is a change in its topology, aiming to provide specific operation conditions of the network, by changing the status of its switches. It can be performed regardless of any system anomaly. The service restoration is a particular case of reconfiguration and should be performed whenever there is a network failure or whenever one or more sections of a feeder have been taken out of service for maintenance. In such cases, loads that are supplied through lines sections that are downstream of portions removed for maintenance may be supplied by the closing of switches to the others feeders. By classical methods of reconfiguration, several switches may be required beyond those used to perform the restoration service. This includes switching feeders in the same substation or for substations that do not have any direct connection to the faulted feeder. These operations can cause discomfort, losses and dissatisfaction among consumers, as well as a negative reputation for the energy company. The purpose of this thesis is to develop a heuristic for reconfiguration of a distribution network, upon the occurrence of a failure in this network, making the switching only for feeders directly involved in this specific failed segment, considering that the switching applied is related exclusively to the isolation of failed sections and bars, as well as to supply electricity to the islands generated by the condition, with significant reduction in the number of applications of load flows, due to the use of sensitivity parameters for determining voltages and currents estimated on bars and lines of the feeders directly involved with that failed segment. A comparison between this process and classical methods is performed for different test networks from the literature about networks reconfiguration

Um estimador de estado trifásico para sistemas de distribuição de energia elétrica com base no método da soma de potências

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Automação da detecção de fraudes em sistemas de medição de energia elétrica utilizando lógica fuzzy em ambiente SCADA

This works presents a proposal to make automatic the identification of energy thefts in the meter systems through Fuzzy Logic and supervisory like SCADA. The solution we find by to collect datas from meters at customers units: voltage, current, power demand, angles conditions of phasors diagrams of voltages and currents, and taking these datas by fuzzy logic with expert knowledge into a fuzzy system. The parameters collected are computed by fuzzy logic, in engineering alghorithm, and the output shows to user if the customer researched may be consuming electrical energy without to pay for it, and these feedbacks have its own membership grades. The value of this solution is a need for reduce the losses that already sets more than twenty per cent. In such a way that it is an expert system that looks for decision make with assertivity, and it looks forward to find which problems there are on site and then it wont happen problems of relationship among the utility and the customer unit. The database of an electrical company was utilized and the datas from it were worked by the fuzzy proposal and algorithm developed and the result was confirmed

Um sistema para simular o comportamento de bancos trifásicos de reguladores de tensão usados em sistemas de distribuição de energia elétrica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Extração e Representação de Conhecimento de Séries Temporais de Demanda de Energia Elétrica Usando TSKR

The opening of the Brazilian market of electricity and competitiveness between companies in the energy sector make the search for useful information and tools that will assist in decision making activities, increase by the concessionaires. An important source of knowledge for these utilities is the time series of energy demand. The identification of behavior patterns and description of events become important for the planning execution, seeking improvements in service quality and financial benefits. This dissertation presents a methodology based on mining and representation tools of time series, in order to extract knowledge that relate series of electricity demand in various substations connected of a electric utility. The method exploits the relationship of duration, coincidence and partial order of events in multi-dimensionals time series. To represent the knowledge is used the language proposed by Mörchen (2005) called Time Series Knowledge Representation (TSKR). We conducted a case study using time series of energy demand of 8 substations interconnected by a ring system, which feeds the metropolitan area of Goiânia-GO, provided by CELG (Companhia Energética de Goiás), responsible for the service of power distribution in the state of Goiás (Brazil). Using the proposed methodology were extracted three levels of knowledge that describe the behavior of the system studied, representing clearly the system dynamics, becoming a tool to assist planning activities

Perspectivas de inserção da energia solar fotovoltaica na geração de energia elétrica no Rio Grande do Norte

The generation of electricity in Brazil is predominantly renewable, with internal hydraulic generation being more than 70% of its energy matrix. The electricity rationing occurred in 2001 due to lack of rain, led the country to increase the participation of alternative energy sources. This need for new sources of energy makes the regional potential to be exploited, which configures the change of generation model from centralized generation to distributed generation. Among the alternative sources of energy, the solar energy is presented as very promising for Brazil, given that most of its territory is located near to the equator line, which implies days with greater number of hours of solar radiation. The state of Rio Grande do Norte (RN) has one of the highest levels of solar irradiation of the Brazilian territory, making it eligible to receive investments for the installation of photovoltaic solar plants. This thesis will present the state-of-the-art in solar photovoltaic power generation and will examine the potential for generation of solar photovoltaic power in Brazil and RN, based on solarimetrics measurements conducted by various institutions and also measurements performed in Natal, the state capital

Modelo de programação matemática para controle do crescimento da vegetação sob redes de distribuição de energia elétrica

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Impacto do racionamento nos resultados das empresas concessionárias do serviço público de distribuição de energia elétrica: um estudo nas empresas privadas da Região Nordeste

This work verifies the impact caused by the Emergencial Program of Reduction of Consumption of Electric Energy (energy-rationing program) in the results of the concessionary private companies of the public service of electric energy distribution localized in the Northeast Area. As the rationing invigorated from June 2001 to February 2002, its effects are diluted in the results presented by these companies in the second semester of 2001 and first quarter of 2002, with prominence for the last quarter of 2001, when the revenue of extraordinary tariff restore was instituted by the National Agency of Electric Energy (ANEEL), consequence of the so-called General Agreement of the Electric Sector made between the federal government and the companies of the electric sector. The structure of a generic electric sector and a historical review of the Brazilian electric sector from the time it was controlled by the private enterprises, including the State control period, about 1960, and returning to the control of the private enterprises in 1990, under a new regulation structure are presented. An explanation of the models of economic regulation that Brazil used for the electric sector is made, with prominence for the price cap that is the actual effective model. The process of tariff revision foreseen in the concession contracts signed by the federal government and the concessionary companies is presented, highlighting its two stages: the tariff rebalancing that defines the new price cap and the calculation of the factor X that establishes the efficiency goals for the companies. There is made a presentation of the Emergencial Program of Reduction of Consumption of Electric Energy and of the consequent General Agreement of the Electric Sector, which created the revenue of extraordinary tariff restore. A conceptual revision on reviews is presented, regarding to concepts, accomplishment and recognition. A brief review of the six companies that made part of the worked sample is also presented. Analyzing the quarters historical review and of amount of sold energy, it was possible to conclude that the energy-rationing altered the results of the studied companies significantly and that alteration was masked by the accounting process of the revenue of extraordinary tariff restore

A Temática Ambiental e o Ensino de Física na Escola Média: Algumas Possibilidades de Desenvolver o Tema Produção de Energia Elétrica em Larga Escala em uma Situação de Ensino

Diversos setores organizados da sociedade têm chamado a atenção para as alterações provocadas pelo homem na natureza e, dentre estas, destacamos aquelas diretamente relacionadas à produção de energia elétrica em larga escala. O debate em torno desta questão limita-se, na maioria das vezes, aos meios técnicos e acadêmicos. Porém um grande número de pessoas vivencia os principais problemas decorrentes da utilização das diversas tecnologias de produção de eletricidade em larga escala. Dentre as propostas que procuram qualificar um grande número de pessoas para participar deste debate, destacamos o processo educativo. Neste sentido, considerando as sugestões presentes em atuais propostas curriculares, procuramos neste trabalho identificar e sistematizar os principais elementos das discussões ocorridas nos meios técnicos e acadêmicos, que versam sobre produção de energia elétrica em larga escala e a temática ambiental e que poderiam ser convertidos em conteúdo escolar.

Algoritmo baseado em afundamentos de tensão para localização de faltas em alimentadores de distribuição de energia elétrica

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Planejamento de Fontes Reativas em Sistemas de Energia Elétrica utilizando a técnica de Decomposição de Benders e o algoritmo de Branch-and-Bound

This paper presents the Benders decomposition technique and Branch and Bound algorithm used in the reactive power planning in electric energy systems. The Benders decomposition separates the planning problem into two subproblems: an investment subproblem (master) and the operation subproblem (slave), which are solved alternately. The operation subproblem is solved using a successive linear programming (SLP) algorithm while the investment subproblem, which is an integer linear programming (ILP) problem with discrete variables, is resolved using a Branch and Bound algorithm especially developed to resolve this type of problem.

Consumo e custo de energia elétrica na cultura de citros irrigado por gotejamento e microaspersão, com três lâminas de água

The objective of this work was to analyze the consumption, electric energy cost, and economic results of irrigated citrus (Citrus sinensis). The treatments consisted of a dripping irrigation system with one and two lateral distribution lines, a micro sprinkler irrigation system and a treatment without irrigation. For each irrigation system, three water depths were used: 100%, 75% and 50% of Etc (citrus evapotranspiration). The electric energy cost for two tariff groups, Group A and Group B, was studied. For Group A, the expenses with energy were determined for the Conventional Binomial Structure tariff, the Hour-seasonal tariff (green and blue) and the special tariff for nocturnal irrigation. The kWh cost for the tariff systems were obtained from the website of CPFL (São Paulo State Power and Light Company, Brazil). The best relation between the electric energy consumption (kWh.ha -1) and productivity (t.ha -1) occurred in the treatment irrigated with 50% of the Etc. The irrigated treatments increased productivity. The biggest productivity was observed in the irrigation treatments with 50% of the Etc when compared to the ones with 100% of the Etc. The blue and green Hour-seasonal tariff system of Group A (nocturnal irrigation) was the best option. A biggest economic turnover occurred in the treatments irrigated with 50% of the Etc.

Microgeração de energia elétrica (Abaixo de 100 kW) utilizando turbina Tesla modificada

An economical electricity generating system is developed, i.e., a boiler and turbine with a capacity ≤ 100 kw, to occupy a niche market where the existing steam systems are not economically viable. A Tesla turbine is used. It has been modified to provide greater torque, outperforming the deficiency inherent in the original Tesla turbine. It can operate with saturated steam produced by a boiler heated by biomass, gas, biodiesel, etc. The microgenerator consumes locally available fuel and can bring energy to millions of rural living Brazilians, where some kind of biomass is abundant. The Tesla turbine is compact, has no moving parts, and has endless application possibilities. A prototype system is also created to produce electricity with a boiler and generator.

Sistema especialista para a monitoração do processo de degradação de medidores tipo indução de energia elétrica ativa

This paper presents a methodology and software for hazard rate analysis of induction type watt-hour meters, considering the main variables related with the degradation process of these meters, for the Elektro Electricity and Services SA. The modeling developed to calculate the watt-hour meters hazard rate was implemented in a tool through a user friendly platform, in Delphi language, enabling not only hazard rate analysis, but also a classification by risk range, localization of installation for the analyzed meters, and, allowing, through an expert system, the sampling of induction type watt-hour meters, based on the model risk developed with artificial intelligence, with the mainly goal of follow and manage the process of degradation, maintenance and replacement of these meters. © 2010 IEEE.