Este trabalho tem por objetivo apresentar o desenvolvimento e a implementacao em uma rotina computacional, de algoritmos para a localizacao de faltas em linhas de transmissao com subestacoes conectadas em derivacao. Os algoritmos propostos neste trabalho integram uma metodologia para localizacao de faltas, que e capaz de identificar corretamente o ponto de ocorrencia do defeito utilizando as componentes de fase dos fasores de tensoes e correntes, calculadas atraves dos registros desses sinais, efetuados por oscilografos digitais e/ou reles de protecao instalados nos terminais da linha de transmissao. Alem disso, a metodologia para localizacao de faltas tem acesso aos parametros eletricos da linha e informacoes sobre o tipo de ligacao e o carregamento dos transformadores conectados aos terminais das derivacoes. Este trabalho apresenta tambem o desenvolvimento dos modelos para os elementos do sistema de transmissao, em componentes de fase. Estes modelos sao utilizados pelos algoritmos que integram a metodologia para localizacao de faltas. / This research presents the development and implementation in a computational routine, of algorithms for fault location in multi-terminal transmission lines. The algorithms proposed in this work are part of a fault location methodology, which is capable of correctly identifying the fault point based on voltage and current phase components. The voltage and current phasors are calculated using measurements of voltage and current signals from intelligent electronic devices, located on the transmission line terminals. The algorithms have access to the electrical parameters of the transmission lines and to information about the transformers loading and their connection type. This work also presents the development of phase component models for the transmission system elements used by the fault location algorithms, that are part of the fault location methodology.

Submitted by Maria Aparecida (cidazen@gmail.com) on 2017-08-02T13:58:14Z No. of bitstreams: 1 Dissertacao Claudio.pdf: 6336618 bytes, checksum: c06faa9f49cc4b573db64e75da62a327 (MD5) / Made available in DSpace on 2017-08-02T13:58:14Z (GMT). No. of bitstreams: 1 Dissertacao Claudio.pdf: 6336618 bytes, checksum: c06faa9f49cc4b573db64e75da62a327 (MD5) Previous issue date: 2013-03-27 / CNPQ / After implantation of the new economic model for power systems, a fair remuneration strategy of transmission companies has become a matter of great importance. This remuneration should be performed by system users, who must pay proportionally to its network usage. However, there is still no consensus about wich is the best criterion to be adopted to allocate these costs. The most widely used methods take into account the power ows only at normal operating conditions. however, it is recognized that the transmission system is planned and operated to accommodate power also at contingency scenarios, which requires additional transmission capacity. Moreover, part of the idle capacity is due to the characteristics of network investments and uncertainty in relation to demand. Thus, the costs allocated by these methods may not re ect the actual usage of the system. In this context, this work presents a transmission cost allocation method that takes into consideration all these network characteristics. The total costs are decomposed into three components, each of these associated with a part of the transmission capacity of the system and its function. These costs are then allocated based on their system usage in diferent operating scenarios. To validate the proposed method, tests are performed on small and medium power systems. Comparisons are established with some methods more used in the literature, where it is observed that the proposed method provides complete consistency with the expected results for the problem. It was also found that this method offers subsidies to consumers allowing them to define their security requirements. / Com a implantação do novo modelo econômico nos sistemas de potência, a adequada remuneração das empresas provedoras de serviços de transmissão tem se tornado um assunto de grande importância. Esta remuneração deve ser realizada pelos usuários do sistema, que devem pagar proporcionalmente ao seu grau de utilização da rede. No entanto, ainda não há um consenso do melhor critério a ser adotado para alocar estes custos. Os métodos mais utilizados levam em consideração os uxos de potência apenas quando a rede opera em condições normais. No entanto, sabe-se que o sistema de transmissão é planejado e operado para acomodar os uxos também em cenários de contingência, o que exige capacidade adicional de transmissão. Além disso, parte da capacidade ociosa é devido às características dos investimentos no setor e à incerteza em relação à demanda. Desta forma, os custos alocados por estes métodos pode não re etir a real utilização do sistema. Neste contexto, este trabalho apresenta um método de alocação dos custos pelo uso da transmissão que leva em consideração todas estas características da rede. Os custos totais são decompostos em três componentes, cada uma destas relacionada com parte da capacidade de transmissão do sistema e sua função. Estes custos são então alocados aos usuários da rede com base no seu grau de utilização do sistema em diversos cenários de operação. Para validar o método proposto, são realizados testes em sistemas de potência de pequeno e médio porte. Comparações são estabelecidas com alguns dos métodos mais aplicados na literatura, onde constata-se que o método proposto apresenta total coerência com os resultados esperados pelo problema. Veri ca-se ainda que este método oferece subsídios aos consumidores para que estes possam de nir quais seus requisitos de segurança.

Submitted by Cátia Araújo (catia.araujo@unipampa.edu.br) on 2017-01-24T12:46:26Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Modelagem de sistemas hidrotérmicos interligados utilizando dinâmica de sistemas.pdf: 1401994 bytes, checksum: 2d15d929f0a041f795111bbdb652abcb (MD5) / Approved for entry into archive by Cátia Araújo (catia.araujo@unipampa.edu.br) on 2017-01-24T12:47:27Z (GMT) No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Modelagem de sistemas hidrotérmicos interligados utilizando dinâmica de sistemas.pdf: 1401994 bytes, checksum: 2d15d929f0a041f795111bbdb652abcb (MD5) / Made available in DSpace on 2017-01-24T12:47:27Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Modelagem de sistemas hidrotérmicos interligados utilizando dinâmica de sistemas.pdf: 1401994 bytes, checksum: 2d15d929f0a041f795111bbdb652abcb (MD5) Previous issue date: 2015-08-28 / A matriz de energia elétrica brasileira é composta predominantemente por geração hídrica, este fato faz com que o país dependa do regime de afluências. A fonte de geração complementar para suprir a demanda do país em períodos de baixa afluência é a geração de energia a partir de usinas termelétricas, porém cada vez que estas usinas entram em operação o custo marginal de curto prazo da energia sobe. O país possui um grande sistema elétrico interligado, em que é possível realizar o intercâmbio de energia entre as regiões, porém a decisão sobre o despacho e o intercâmbio de energia é tarefa complexa. Esta decisão é tomada pelo Operador Nacional do Sistema Elétrico (ONS) com auxílio dos modelos Newave e Decomp, porém estes modelos são complexos e pouco flexíveis, além da lenta resposta a uma determinada ação. Devido a este fato, o presente trabalho busca uma alternativa para auxiliar no teste de ações e na obtenção de respostas futuras a partir de ações adotadas no presente, com um tempo rápido de resposta. Para isto é utilizada a técnica de Dinâmica de Sistemas que busca modelar as relações de causa-efeito realimentadas, visando compreender as implicações sobre o desempenho do sistema sob estudo. O modelo elaborado leva em consideração as principais variáveis que compõem o sistema elétrico brasileiro como Energia Natural Afluente (ENA), Geração Termo, Geração Hidro, Geração eólica, Carga de Energia, Energia armazenada e o Custo Variável Unitário (CVU) das unidades térmicas. Os principais objetivos são compreender o funcionamento do Sistema Interligado Nacional, auxiliar na decisão de utilizar a água dos reservatórios no presente ou economizar para o futuro, bem como obter as consequências dessa decisão no Preço de Liquidação das Diferenças(PLD) e no intercâmbio de energia entre os subsistemas, além de analisar a influência de diferentes cenários de ENA e Geração eólica no sistema.Com o modelo desenvolvido foi possível mostrar a importância do intercâmbio de energia entre os subsistemas a fim de evitar possíveis situações de déficit. A principal contribuição do modelo foi obtida com a aplicação de cenários de ENA e Geração Eólica, com um acréscimo de 10% na curva de ENA verifica-se a redução de diversas situações com déficit e do PLD, enquanto que com uma redução de 10% na curva de ENA os períodos com déficit e o PLD alto aumentaram significativamente. / The Brazilian energy matrix is composed predominantly hydroelectric generation, this fact makes the country dependent on the inflow regime. The source of additional generation to meet the country's demand in low peak times is the generation of energy from thermal power plants, but increasingly these plants become operational marginal cost of short-term energy rises. The country has a large interconnected power system, it is possible to carry out the exchange of energy between regions, but the decision about dispatch and exchange of energy is a complex task. This decision is made by the National Electric System Operator (ONS) with the help of Newave and Decomp models, but these models are complex and inflexible, besides the slow response to a particular action. Due to this fact, this paper seeks an alternative to aid in the stock test and obtaining future responses from actions taken in the present, with a fast response time. For this is used the system dynamics technique that seeks to model the relationships of cause and effect fed back, to understand its effects on the performance of the system under study. The elaborate model takes into account the main variables that make up the Brazilian electrical system as Energy Affluent Natural (ENA), Generation Instrument, hydro generation, wind generation, power load, stored energy and the Variable Cost per Unit (CVU) of thermal units. The main objectives are to understand the operation of the National Interconnected System, assist in the decision to use water from reservoirs in the present or save for the future and get the consequences of this decision in the Settlement of Differences Price (PLD) and energy exchange between subsystems, and analyze the influence of different scenarios of ENA and wind generation in the system. With the developed model was possible to show the importance of the exchange of energy between the subsystems in order to avoid possible deficit situations. The main standard contribution was obtained by applying ENA scenarios and Generation Wind, with a 10% increase in ENA curve was possible to eliminate various situations with deficit and reduce the PLD, whereas with a 10% reduction in the curve ENA periods with high deficit and the PLD increased significantly.

O estudo da proteção em sistemas elétricos de potência representa um tópico de grande relevância proporcionando continuidade do serviço e segurança da operação. Hoje, a coordenação de relés direcionais de sobrecorrente (RDSs) é realizada usando formulações matemáticas que basicamente levam em consideração o tempo de operação dos dispositivos e o atendimento ao intervalo de tempo de coordenação (ITC). Nesta tese tem sido realizada a coordenação e seletividade entre RDSs considerando a otimização simultânea das unidades temporizada e instantânea de fase e neutro, contingências em circuitos mutuamente acoplados e ajuste automático das curvas. Algumas questões como os critérios de curtos-circuitos e tratamento topológico para circuitos interligados são também discutidas. Inicialmente, os estudos foram tratados como Otimização Monobjetivo (soma ponderada) minimizando a soma do tempo dos relés primários quando aplicado um curto-circuito do tipo close-in, na barra remota e a soma dos ajustes da unidade de sobrecorrente instantânea. Em sequência duas abordagens envolvendo um aspecto multiobjetivo são propostas. A primeira minimiza o tempo de operação de todos dispositivos de proteção, enquanto maximiza um índice de coordenação, ocasionando então em ITC variável. Já a segunda, além de minimizar o tempo de operação, o número de ajustes permitidos a serem alterados é limitado pelo operador, se a coordenação de todos elementos envolvidos for inviável. Os ajustes dos RDSs são obtidos por meio de algoritmos meta-heurísticos (derivados do Particle Swarm Optimization e Non-dominated Sorting Genetic Algorithm-II. Os métodos modernos ou inteligentes, concebidos a partir de conceitos de inteligência artificial, têm evoluído rapidamente e permitem a obtenção de excelentes soluções com a confiabilidade adequada para aplicações em engenharia. A eficácia e robustez do método são realizadas em um sistema de transmissão pertencente à área de uma concessionária brasileira. Por fim, os resultados foram bem satisfatórios visto que o emprego da unidade instantânea e múltiplas curvas diminuiu substancialmente a soma de tempo de atuação dos dispositivos de proteção, contribuindo para minimizar o trabalho empregado pelo engenheiro de proteção com segurança e rica informação técnica. Ademais, as estratégias multiobjetivos auxiliam o operador na tomada de decisão uma vez que cada solução encontrada atende específicas restrições oriundas do equipamentos empregados ou estados contingenciais da rede. / The study of power system protection represents a highly relevant topic providing continuity of service and safety of operation. Today, the coordination of directional overcurrent relays (DORs) is performed using mathematical formulations that basically take into account the operation time of the devices and the coordination time interval (CTI). In this thesis, coordination and selectivity between DORs have been performed considering the simultaneous optimization of the instantaneous and time overcurrent unit (both phase and ground), contingencies in coupled mutually circuits and automatic determination of the curves. Some issues are also discussed such as criteria for short-circuit calculation and topological treatment for interconnected circuits. Initially, the studies were considered as being a case of Monobjective Optimization (weighted sum) by minimizing the sum of operation time of primary relays when occur close-in and line-end faults and also the sum of the instantaneous overcurrent unit. In sequence are proposed two approaches involving multiobjective aspect. The first minimizes the operating time of all protection devices, while maximizing a coordination index (here, CTI is non-fixed). The second, besides minimizing the operating time, the number of settings allowed to alter is limited by operator, if the coordination of all elements involved is not possible in practice. The settings of DORs have been found by using meta-heuristic algorithms (derived from Particle Swarm Optimization and Non-dominated Sorting Genetic Algorithm-II). Modern or intelligent methods, conceived from artificial intelligence, have evolved rapidly and obtained excellent solutions with the acceptable reliability for engineering applications. The test has been carried out on a transmission network from a Brazilian utility. Finally, the results were well satisfactory because using the instantaneous unit and multiple curves substantially reduced the sum of operating time of the protective devices, contributing to decrease workload of protection engineers with safety and rich technical information. In addition, the multiobjective strategies help the operator in the decision making since each solution satisfies specific constraints coming from used equipment or contingency states of the existing network.

There are definitely many reasons for choosing off-grid wind power systems. Few key ones involve the positive enhancement of societies, economies and natural environments. From a project developers’ perspective these systems provide a large potential market, which can cover a wide range of applications with relatively reasonable costs.  In spite of this, many challenges may interfere with the diffusion and the success of such systems. In the report we discuss the various factors affecting  the implementation of off-grid wind power systems and demonstrate some of the challenges project developers may be facing during the planning stage. Some of these include the acceptance of stakeholders (local inhabitants in particular) and the securing of the financing of the projects.  Another noted challenge lying outside the control of project developers was found to be the absence of encouraging policies and incentives. As a conclusion the thesis provides a set of self-interpreted recommendations along with a flow chart. The concluded summary indicates some key factors that project developers should be aware of and careful when dealing with, these which include: The choice of the site, verification of projects’ economics along with the securing of a convenient finance. The recommendations also point out the great advantage in having local developers as these tend to be more capable in building relations with the local citizens and politicians.

Present demagnetization methods for large power system transformers are time consuming and can be dangerous to persons performing demagnetization. The work of this thesis was to develop improved demagnetization methods and to construct an automated instrument that would implement the methods developed. One previously developed method was analyzed for effectiveness. Then, two new methods for demagnetization were developed and also analyzed for effectiveness. An automated test instrument prototype was redesigned to be able to accommodate these methods and to improve the safety of the user. The previously developed method attempts demagnetization based on current flow behavior characteristics. The first new method is a magnetic flux estimation based on saturation time. The second new method is also based on measuring saturation time, modified to account for the variable voltage loss due to wire resistance. The second of the two new methods developed proved to be the most effective for demagnetization and was able to demagnetize a transformer within an error margin of 2%. The instrument designed to perform the demagnetization with this new routine is now in early production stages for an expanded field trial with transformer maintenance teams.

Increasing penetration of non-dispatchable renewable energy resources and greater peak power demand present growing challenges to Bulk Power System (BPS) reliability and resilience. This research investigates the use of an Internet of Things (IoT) framework for large scale Distributed Energy Resource (DER) aggregation and control to reduce energy imbalance caused by stochastic renewable generation. The aggregator developed for this research is Distributed Energy Resource Aggregation System (DERAS). DERAS comprises two AllJoyn applications written in C++. The first application is the Energy Management System (EMS), which aggregates, emulates, and controls connected DERs. The second application is the Distributed Management System (DMS), which is the interface between AllJoyn and the physical DER. The EMS runs on a cloud-based server with an allocated 8 GB of memory and an 8 thread, 2 GHz processor. Raspberry Pis host the simulated Battery Energy Storage System (BESS) or electric water heater (EWH) DMSs. Five Raspberry Pis were used to simulate 250 DMSs. The EMS used PJM's regulation control signals, RegA and RegD, to determine DERAS performance metrics. PJM is a regional transmission organization (RTO). Their regulation control signals direct power resources to negate load and generation imbalances within the BPS. DERAS's performance was measured by the EMS server resource usage, network data transfer, and signal delay. The regulation capability of aggregated DER was measured using PJM's resource performance assessment criteria. We found the use of an IoT framework for DER aggregation and control to be inadequate in the current network implementation. However, the emulated modes and aggregation response to the regulated control signal demonstrates an excellent opportunity for DER to benefit the BPS.

[Truncated abstract] The present thesis is devoted to the development of new methods for transient stability-constrained optimal power flow, probabilistic transient stability assessment and security-constrained ancillary services allocation. The key objective of the thesis is to develop novel dispatch and assessment methods for power systems operation in the new environment of electricity markets to ensure power systems security, particularly transient stability. A new method for economic dispatch together with nodal price calculations which includes transient stability constraints and, at the same time, optimises the reference inputs to the Flexible AC Transmission System (FACTS) devices for maintaining power systems transient stability and reducing nodal prices is developed. The method draws on the sensitivity analysis of time-domain transient stability simulation results to derive a set of linearised stability constraints expressed in terms of generator active powers and FACTS devices input references. '...' The low computing time requirement of the two-point estimate method allows online applications, and the use of detailed power systems dynamic model for time-domain simulation which offers high accuracy. The two-point estimate method is integrated in a straightforward manner with the existing transient stability analysis tools. The integrated software facility has potential applications in control rooms to assist the system operator in decision making process based on instability risks. The software system when implemented on a cluster of processors also makes it feasible to re-assess online transient stability for any change in system configuration arising from switching control. The method proposed has been tested on a representative power system and validated using the Monte Carlo simulation. In conjunction with the energy market, by which forecasted load demand is met by generator dispatch, ancillary services are required in relation to control for secure system operation and power quality. The final part of the thesis has a focus on the key aspect of allocating these ancillary services, subject to an important constraint that the dispatch of the ancillary services will not impair the system security achieved in the load dispatch. With this focus and requirement, the thesis develops a new dispatch formulation in which the network security constraints are represented in the optimal determination of generator active power schedule and allocation of ancillary services. Contingencies considered include power demand variations at individual load nodes from the values specified for the current dispatch calculation. The required changes in generator active powers to meet the new load demands are represented by additional control variables in the new dispatch formulation which augment those variables in the traditional OPF dispatch calculation. Based on the Lagrange function which includes the extended set of security constraints, the formulation derives the optimality condition to be satisfied by the dispatch solution, together with the marginal prices for individual ancillary service providers and LMPs. The effects of the security constraints are investigated and discussed. Case studies for representative power systems are presented to verify the new dispatch calculation procedure.

With the increased attention on high efficiency and controllability of industrial processes, as well as reduced weight, volume and cost of consumer products, the applications of nonlinear power electronic converters such as adjustable speed drives (ASDs) are showing a rapid rise. Power Quality (PQ) is becoming an increasing concern with the growth of both sensitive and disturbing nonlinear loads in the residential, commercial and industrial levels of the power system, where PQ related disruptions can cause system malfunction, product loss, and hardware damage resulting in costly data loss and downtime. Investigating and mitigating PQ issues pertaining to the input supply of ASDs and other sensitive power electronic equipment is extremely important in maintaining a high level of productivity. In response to these concerns, this research focuses on the development of a power quality test platform (PQTP) that has been implemented at Oregon State University (OSU), in the Motor Systems Resource Facility (MSRF). The central component of the PQTP is a 120kVA programmable ac power source with an integrated arbitrary waveform generator (AWG) which creates realistic voltage disturbance conditions that can be used to characterize ride-through capabilities of industrial processes in a controlled environment. Also presented is a command driver database that has been created and tested, using Lab VIEW, which contains the functionality necessary to conduct a wide range of power quality research and testing projects by remotely configuring and controlling the AWG. The power quality research and testing capabilities of the PQTP are demonstrated with ASD diode-bridge rectifier operation analysis and ride-through characterization. This research shows the transition of an ASD's three-phase diode rectifier into single-phase diode rectifier operation when relatively small single-phase voltage sags are applied to the input. Also shown are ride-through characterizations of varying sizes and configurations of ASDs when subjected to single, two, and three-phase voltage sags as well as capacitor switching transients. In addition, ASD topologies providing improved ride-through capabilities are determined. / Graduation date: 2002

This thesis describes a systematical study, including multidisciplinary modeling, simulation, control, and optimization, of a fuel cell - gas turbine hybrid power system that aims to increase the system efficiency and decrease the energy costs by combining two power sources. The fuel cell-gas turbine hybrid power systems can utilize exhaust fuel and waste heat from fuel cells in the gas turbines to increase system efficiency. This research considers a hybrid power system consisting of an internally reforming solid oxide fuel cell and a gas turbine. In the hybrid power system, the anode exhaust, which contains the remainder of the fuel, is mixed with the cathode exhaust as well as an additional supply of fuel and compressed air and then burned in a catalytic oxidizer. The hot oxidizer exhaust is expanded through the turbine section, driving an electric generator. After leaving the gas turbine, the oxidizer exhaust passes through a heat recovery unit in which it preheats the compressed air that is to be supplied to the fuel cell and the oxidizer. This research concentrates on multidisciplinary modeling and simulation of the fuel cell-gas turbine hybrid power system. Different control strategies for the power sharing between the subsystems are investigated. Also, the power electronics interfaces and controls for the hybrid power system are discussed. Two different power sharing strategies are studied and compared. Simulation results are presented and analyzed. Transient response of the hybrid energy system is studied through time-domain simulation. In addition, in this effort, Particle Swarm Optimization (PSO) is used to optimize the power sharing for the hybrid power system to increase the efficiency and decrease the fuel consumption.