O objetivo deste trabalho é o desenvolvimento de \"software\" para proteção digital das linhas de transmissão. Com esse propósito são implementados relés de distância com características quadrilaterais e adaptativas. Um \"software\" básico para este fim consiste de várias etapas como: detecção da falta, filtragem digital, classificação da falta, cálculo da impedância aparente e verificação das zonas de proteção. Na etapa de filtragem digital das ondas, é utilizada a Transformada Discreta de Fourier (TDF) para a extração dos componentes fundamentais de tensão e corrente. A característica quadrilateral mostra-se eficiente para determinadas condições de operação fixas do sistema, mas seu desempenho é comprometido quando ocorrem mudanças das mesmas. Para solucionar este problema, é introduzida a teoria de relés adaptativos onde a característica de abertura do relé digital muda com as alterações nas condições de operação do sistema, mantendo-se assim a eficiência da proteção. / The objective of this work is the development of a software for digital protection of transmission lines. For this purpose relays of distance with Quadrilateral and Adaptive characteristics are implemented. A basic software with this aim consists of several steps such as: detection of the fault, digital filtering of the faulted waves, classification of the fault, impedance calculation and verification of the protection zones. For the digital filtering purpose, the Fourier Discret Transform, is used in order to extract the fundamental phasors of voltages and currents. Quadrilateral characteristcs are shown to be effective under certain operation conditions of the system, but its performance is not so efficient when those conditions are changed. In order to solve these problems, the theory of adaptive relays was introduced whereby the characteristic of digital relay changes according to the alterations in the conditions of the system operation, and by these means the protection is kept efficient.

CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / Ericsson Brasil / In this dissertation, we present a distributed data estimation and detection approach for the uplink of a network that uses CDMA at transmitters (users). The analyzed network can be represented by an undirected and connected graph, where the nodes use a distributed estimation algorithm based on consensus averaging to perform joint channel and symbol estimation using a receiver based on tensor signal processing. The centralized receiver, developed for a central base station, and the distributed receiver, developed for micro base stations, have their performances compared in a heterogeneous network. Then, two tensor-based receivers are proposed to be used in a relay-assisted network. In this case, the proposed receiver makes use of collaborative signal processing among relays to recover sources information before forwarding to the base station using a Decode-and-Forward protocol. The first receiver is based on the uncoded transmission of the tensor data reconstructed by the relays from the estimation of their factors matrix. The second one considers a tensor encoding of symbols estimated at the relays before transmission to the base station. The different proposed receivers are compared by means of computer simulations in terms of convergence and bit error rate. / Nesta dissertaÃÃo, apresentamos uma abordagem distribuÃda para a estimaÃÃo e detecÃÃo de dados para uplink em uma rede que emprega CDMA nos transmissores (usuÃrios). A rede analisada pode ser representada por um grafo sem direÃÃo e conectado, em que os nÃs fazem uso de um algoritmo de estimaÃÃo distribuÃda baseado em consenso mÃdio para realizar a estimaÃÃo conjunta de sÃmbolos transmitidos e do canal, utilizando um receptor baseado em processamento tensorial. O receptor centralizado, operando em uma EstaÃÃo RÃdio Base central, e o receptor distribuÃdo, operando em Micro EstaÃÃes RÃdio Base, tÃm seus desempenhos comparados em uma rede heterogÃnea. Em seguida, considerando-se uma rede assistida por repetidores, dois receptores tensoriais sÃo propostos. Neste caso, fazemos uso de um processamento de sinais colaborativo entre os repetidores para a recuperaÃÃo da informaÃÃo transmitida pela fonte, antes de ser encaminhada para estaÃÃo rÃdio base fazendo uso do protocolo Decode-and-Forward. O primeiro receptor à baseado na transmissÃo nÃo codificada do tensor de dados reconstruÃdo pelos repetidores a partir da estimaÃÃo de suas matrizes fatores. O segundo considera uma codificaÃÃo tensorial dos sÃmbolos previamente estimados nos repetidores antes da transmissÃo para estaÃÃo rÃdio base. Os diferentes receptores propostos sÃo comparados atravÃs de simulaÃÃes computacionais em termos de convergÃncia e taxa de erro de bit.

Orientador: Fujio Sato / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-21T20:17:53Z (GMT). No. of bitstreams: 1 Oliveira_Wagnerde_M.pdf: 29762769 bytes, checksum: a8dc59d5c389eb687d639b8519c57213 (MD5) Previous issue date: 2012 / Resumo: Neste trabalho, intitulado "Simulação para a Avaliação do Desempenho do Sistema de Proteção de Distância de uma Linha de Transmissão de 500 kV", são descritos os princípios básicos das proteções dos sistemas de potência, a evolução dos equipamentos e dos procedimentos de ensaios, simulações em tempo real, análise de desempenho de um sistema de proteção de linha de transmissão e simulações no modelo computacional. Nos Capítulo 1 e 2 são destacados alguns aspectos importantes do sistema de potência, seguido de noções de proteção de linhas de transmissão, realçando os relés de distância e o esquema de teleproteção. No Capítulo 3 são descritos a evolução dos equipamentos e procedimentos para os ensaios, concomitante aos avanços tecnológicos dos relés de proteção, desde os relés eletromecânicos até os relés numéricos. No Capítulo 4 são descrito as simulações em tempo real e as análises dos resultados. Estas simulações foram executadas na LT 500 kV Tucuruí-Vila do Conde que integra o Sistema Norte-Nordeste da ELETRONORTE e EATE, utilizando o RTDS. As saídas em forma de sinais analógicos (tensões e correntes) e digitais (eventos) possibilitaram as análises de desempenhos dos relés, do sistema de teleproteção e disjuntores. E no Capítulo 5 temos a parte final da dissertação, demonstrando o desenvolvimento de um modelo computacional para simular as trajetórias das impedâncias de faltas de forma a confrontá-las com as características quadrilaterais de impedância do relé de distância REL 531 no plano R-X utilizado durante a simulação no RTDS, o que permitiu a análise dos ajustes das zonas de proteção / Abstract: This work, entitled "Simulation for Performance Evaluation System of Distance Protection of a Transmission Line 500 kV," describes the basic principles of protection of power systems, the evolution of equipment's and testing procedures, real-time simulations performance analysis of a system of protection of transmission line and the computer model simulations. In Chapter 1 and 2 are highlights some important aspects of the power system, followed by notions of protection of transmission lines, enhancing distance relays and pilot relaying scheme. In Chapter 3 describes the evolution of equipment and procedures for testing, concomitant technological advances of protective relays from electromechanical relays by numerical relays Described in Chapter 4 are the real-time simulations and analyzes of the results. These simulations were performed at 500 kV Tucuruí-Vila do Conde system which integrates the North and Northeast ELETRONORTE and EATE using the RTDS. The outputs in the form of analog signals (voltages and currents) and digital signals (events) enabled the analysis of performances of relays, pilot relaying scheme (teleprotection system) and circuit breakers. In the Chapter 5, we have the final part of the dissertation, demonstrating the development of a computational model to simulate the trajectories of impedances faults in order to compare them with the quadrilateral characteristics parameters of the distance protection zones REL 531 line protection plane used during R-X RTDS simulation, which allowed the analysis of the protection zone adjustments / Mestrado / Energia Eletrica / Mestre em Engenharia Elétrica

Nos Sistemas de Automação de Subestação atuais são utilizados equipamentos digitais chamados IED (Dispositivos Eletrônicos Inteligentes), incorporando as funções de proteção, automação e medição. Estes, para trocarem informações entre si, utilizam um canal de comunicação serial, sendo os dados transmitidos de forma digital por meio de vários protocolos, muitos deles proprietários, o que dificulta a integração entre eles. Neste cenário entra a norma IEC 61850 oferecendo um padrão a ser seguido entre os fabricantes de IED. Este trabalho tem por objetivo apresentar um estudo da norma e a análise de sua aplicação no Sistema de Automação de Subestação. O estudo proposto da norma a analisará utilizando os principais conceitos estabelecidos por ela para atingir os objetivos propostos: interoperabilidade, liberdade de configuração e estabilidade a longo prazo. Como ensaio de aplicação da norma será apresentado um comparativo com um protocolo utilizado atualmente e a implementação de funções de proteção. No comparativo entre protocolos foi escolhido o DNP3, um dos mais utilizados atualmente no setor elétrico, com o objetivo de verificar as principais diferenças entre eles e vantagens de cada um. Para a implementação de funções de proteção foram escolhidos dois exemplos: a falha de disjuntor e o bloqueio reverso, implementadas da forma tradicional, por meio de sinais elétricos de comando transmitidos por cabos, e por meio dos serviços de mensagens prioritárias da IEC 61850, com o objetivo de analisar suas dinâmicas, seus tempos de atuação e o comportamento frente a eventuais defeitos. / In current Substation Automation System, digital equipaments called IED (Intelligent Electronic Devices) are used with protection, automation and measurement functions incorporated. These devices, to exchange information among them, use serial communication buses with information transmitted in digital form through many procotols, many of them proprietary, making their integration very hard. In this scene, IEC61850 standard appears offering a standard to be followed by IED manufacturers. This research presents a IEC 61850 standard study and an analysis of its application in Substation Automation System. The proposed study will analise the standard through the most important topics used by the standard to reach its main goals: interoperability, free configuration and long-term stability. In the application analysis, a comparative with a protocol used nowadays and a implementation of protection functions will be presented. In the comparative between protocols the chosen was DNP3, one of most used protocols in electric plants, with the purpose of verifying the main diferences and advantages of each one. Two examples of protection functions implementation were chosen: breaker failure and reverse blocking, implemented through traditional techniques, using wires and electrical signals, and through high performance IEC 61850 services, with the purpose of analising their dynamics, their actuation times and their behavior in eventual failures.

Dans les systèmes de communications sans fils, l'allocation de ressources reste toujours un défi considérable afin de satisfaire les demandes des utilisateurs et de fournir de bonnes performances avec une perpétuelle demande en applications gourmandes en ressources. Les techniques multiporteuses essentiellement les techniques dérivant de l'OFDM sont généralement utilisées pour transmettre les données dans des sous-porteuses orthogonales. De plus, de nouvelles stratégies de relayage sont proposées pour améliorer les performances en bordures de cellules. Plusieurs types de relais peuvent être sollicités comme les relais fixes faisant partie de l'infrastructure du système ou les relais mobiles qui ne nécessitent pas un coût additionnel de déploiement.Dans cette thèse, nous étudions principalement l'allocation des ressources pour le sens montant d'un système cellulaire OFDMA assurant les exigences de qualité de service et l'équité entre les utilisateurs. Les algorithmes d'allocation de ressources les plus utilisés sont présentés et un nouvel algorithme se basant sur l'équité proportionnelle pondérée (WPF) est proposé afin d'approcher les bornes supérieures de débit et d'équité. L'algorithme WPF propose un poids variable par utilisateur permettant d'allouer un nombre plus élevé de sous-porteuses au centre de la cellule qu'en bordure tout en gardant une bonne équité entre les utilisateurs. Nous établissons une étude théorique afin de comparer l'algorithme proposé à l'algorithme classique d'équité proportionnelle (PF). Nous étendons ensuite l'algorithme WPF à un système multi-cellulaire où l'interférence inter-cellulaire (ICI) dégrade les performances du système. Enfin, nous étudions les stratégies d'annulation de l'ICI et proposons une nouvelle méthode pour réduire l'ICI en se basant sur la coopération entre les stations de base (BSs) et sur les indicateurs d'interférence. Nous proposons un nouvel indicateur d'interférence (EII) à valeurs entières échangé par les BSs pour indiquer les niveaux d'interférence des sous-porteuses. En prenant en compte les valeurs de EII échangées, chaque BS alloue dynamiquement les sous-porteuses de manière à éviter de fortes valeurs d'ICI.Dans un deuxième temps, nous étudions la communication coopérative en utilisant des relais mobiles. Pour cela, de simples utilisateurs mobiles ayant des positions avantageuses peuvent relayer d'autres utilisateurs en bordure de cellule en plus de transmettre leurs propres données. Un relai utilisant le protocole DF multiplexe ainsi ses propres données aux données relayées avant de transmettre à la BS. L'allocation de ressource est formulée sous forme d'un problème d'optimisation dont le but est de minimiser la puissance totale d'émission du système tout en assurant un débit cible par utilisateur. Dans un premier temps, nous proposons une méthode de sélection des relais comme phase d'initialisation et offrons une heuristique itérative pour optimiser l'allocation de puissance et des blocs de ressources radio (RBs). Dans un second temps, nous traitons la sélection des relais comme une variable d'optimisation additionnelle. Pour la résolution, la décomposition de Lagrange et la méthode duale sont utilisées et le problème global est divisé en sous problèmes résolus de manière itérative afin d'approcher la solution optimale. Enfin, nous étendons ce modèle coopératif à un modèle à antennes multiples (MIMO) afin d'étudier l'influence des antennes multiples sur la puissance totale de transmission. Les paramètres à optimiser sont la sélection des relais, l'allocation des puissances et l'allocation des RBs. Afin d'allouer la puissance sur les antennes d'un utilisateur, nous avons étudié la répartition égale des puissance (EPA) et le beamforming. Les expressions théoriques correspondantes sont établies et les résultats de simulation sont présentés pour comparer le modèle avec EPA et le modèle avec beamforming au modèle non coopératif. / In wireless systems, resource allocation is still an important challenge to satisfy user requirements and to ensure good system performances with always greedy data applications. Multicarrier techniques especially the Orthogonal Frequency Division Multiplexing (OFDM) techniques are generally used to carry data into orthogonal subcarriers. Furthermore, relaying strategies are used to enhance cell edge performances. Many types of relays can be investigated as fix relays being part of the network infrastructure or mobile relays without additional deployment cost.In this thesis, we mainly consider the resource allocation for an uplink Orthogonal Frequency Division Multiple Access (OFDMA) system for a cellular system model ensuring Quality of Service (QoS) requirements and fairness between users. The most used resource allocation algorithms are presented and a novel Weighted Proportional Fair (WPF) algorithm is proposed to approach upper bounds of both throughput and fairness. The WPF algorithm considers user weights to allocate more subcarriers in the cell center than in the cell edge keeping sufficient fairness between users. We establish a theoretical analysis to compare the behavior of the proposed WPF algorithm to the classical Proportional Fair (PF) algorithm. Then, we extend this WPF algorithm to a multi-cell system model where the Inter-Cell Interference (ICI) limits the system performance. Moreover, we study ICI mitigation strategies and propose a novel method to reduce the ICI based on Base Station (BS) cooperation and interference indicators. We propose the Enhanced Interference Indicator (EII) with integer values to be exchanged by the BSs indicating interference levels for the subcarriers. Function of these communicated EII values, each BS allocates dynamically subcarriers in order to reduce the ICI. Our contributions in the multi-cell system model are the WPF and the EII.Moreover, we investigate in this dissertation the cooperative communication using mobile relays and propose multiple contributions. For this, simple mobile users with advantageous positions can relay cell edge users to carry data to the BS in addition to their own data. A Decode and Forward (DF) relay multiplex then its own data and relayed data before transmitting to the BS. The resource allocation is formulated as an optimization problem aiming to minimize the system transmit power and respecting a required target data rate per user constraint. In a first time, we propose an initialization method for the paring step to associate source-relay pairs and propose an iterative heuristic to optimize both power and Resource Blocks (RB) allocations. In a second time, we consider the relay selection as an optimization variable in addition of power and RB allocations. For resolution, Lagrangian decomposition and Dual method are used and the global problem is divided into subproblems iterativelly resolved to approach the optimal solution. Finally, we extend this cooperative system model to a Multiple Input Multiple Output (MIMO) system model to study the influence of multiple antennas on the system transmit power. The features to optimize are relay selection, power and RBs allocation. Moreover, to allocate power in the different antennas for each user, both Equal Power Allocation (EPA) and beamforming are studied. Theoretical expressions are established and simulations results are presented to compare EPA, beamforming and non-cooperative system.

Relays can be used in cellular systems to increase coverage as well as reduce the total power consumed by mobiles in a cell. This latter benefit is particularly useful for mobiles operating on a depleted battery. The relay can be a mobile, a car or any other device with the appropriate communication capabilities. In thesis we analyze the impact of using relays under different situations. We first consider the problem of reducing total power consumed in the system by employing relays intelligently. We find that in a simulated, fully random, mobile cellular network for CDMA (Code Division Multiple Access), significant energy savings are possible ranging from 1.76 dB to 8.45 dB. In addition to reducing power needs, relays can increase the coverage area of a cell by enabling mobiles located in dead spots to place relayed calls. We note that use of relays can increase the useful service area by about 10% with real life scenarios. We observe that in heavy building density areas there is more need of relays as compared to low building density areas. However, the chance of finding relays is greater in low building density areas. Indeed, having more available idle nodes helps in choosing relays, so we conclude that unlike present day implementations of cellular networks, the base station should admit more mobiles (beyond the capacity of the cell) even if they are not placing calls since they can be used as relays. One constraint of using relays is the potential to add interference in the same cell and in neighboring cells. This is particularly true if the relays are not under power control. Based on our analysis, we conclude that in interference limited systems like CDMA the relays have to be under power control otherwise we will reduce the total capacity by creating more dead spots. Thus, we believe that either the base station should be responsible to allocate relays or relays should be provided with enough intelligence to do power control of the downlink. Finally, we show how utility of data services can be increased by use of relays.

We present an Ethash-based blockchain relay that utilizes Off-Chain Computation (OCC) to validate block headers on-chain. Current work compromises on fundamental ideas of the blockchain concept: they either require a centralized entity, require a centralized Trusted Third Party (TTP) or are built on economic assumptions. That way, they try to circumvent the on-chain cost-heavy Ethash computation. We utilize Zero Knowledge Proofs (ZKPs) to outsource the Ethash validation to an Off-Chain Computation Framework (OCCF) and only verify the validity of the OCC on-chain. The required dataset for the Ethash validation is inserted into a merkle tree for computational feasibility. Additionally, we validate multiple block headers in batches to further minimize on-chain costs. The on-chain costs of our batch validation mechanism are minimal and constant since only the proof of an OCC is verified on-chain. Through merkle proofs we enable the efficient inclusion of intermediary block headers for any submitted batch. The OCC is feasible on average consumer hardware specifications. Our prototype verifies 5 block headers in a single proof using the ZoKrates framework. Compared to current approaches we only use 3.3% of the gas costs resulting in a highly scalable alternative that is trustless, distributed and has no economic assumptions. For future work, we propose to distribute the computational overhead of computing Ethash inside a ZKP through an off-chain distribution module. This is because we rely on the concurrent execution of the OCC by at least 36 active participants to catch up with the current state of the relay’s blockchain. / Vi presenterar ett Ethash-baserat blockchain-relä som använder sig av Off-Chain Computation (OCC) att validera blockhuvuden i kedjan. Nuvarande arbete kompromissar med grundläggande idéer om blockchain-konceptet: de kräver antingen en centraliserad enhet, kräver en centraliserad Trusted Third Party (TTP) eller bygger på ekonomiska antaganden. På så sätt försöker de kringgå den kostnadstunga Ethash-beräkningen på kedjan. Vi använda Zero Knowledge Proof (ZKP) för att lägga ut Ethash-valideringen på en Off-Chain Computation Framework (OCCF) och verifiera endast giltigheten av OCC på kedjan. Den nödvändiga datamängden för Ethash-valideringen är infogas i ett merkleträd för beräkningsmöjlighet. Dessutom validerar vi flera blockhuvuden i omgångar för att ytterligare minimera kostnader i kedjan. På-kedjan kostnaderna för vår batchvalideringsmekanism är minimala och konstanta eftersom endast bevis på en OCC verifieras i kedjan. Genom merkle proofs möjliggör vi det effektiva inkludering av mellanliggande blockrubriker för alla inlämnade partier. OCC är genomförbart i genomsnitt konsumenthårdvaruspecifikationer. Vår prototyp verifierar 5 blockhuvuden i ett enda bevis med hjälp av ZoKrates-ramverket. Jämfört med nuvarande tillvägagångssätt vi använder bara 3,3% av gaskostnaderna vilket resulterar i ett mycket skalbart alternativ dvs förtroendelös, distribuerad och har inga ekonomiska antaganden. För framtida arbete, föreslår vi för att distribuera beräkningsoverheaden för beräkning av Ethash inuti en ZKP genom en distributionsmodul utanför kedjan. Detta beror på att vi skulle förlita oss på det samtidiga utförandet av OCC med minst 36 aktiva deltagare för att komma ikapp med det aktuella tillståndet för reläets blockkedja.

A shipboard power system (SPS) should be stable and reliable in order to ensure that the ship has better fight-through capability and increased fault invulnerability. The protection system is designed to minimize the effects of faults in the SPS, which presents challenges, such as increased fault vulnerability and lack of an electrical ground in the system. If protection devices are not updated after power system reconfiguration, they may not protect the power system appropriately. Therefore the development of elaborate digital protection devices for the SPS is required. This thesis focuses on the model-based methodology for designing a protection scheme for SPS based on instantaneous overcurrent digital relays. To achieve this, an instantaneous overcurrent relay model is first developed in MATLAB/Simulink. Then, the Simulink model is downloaded to the DSP-based platform dSPACE, which runs the Simulink model in real-time, to perform hardware-in-the-loop testing (HIL). Thus, through the dSPACE hardware, the proposed relay model is tested for various fault conditions in three HIL platforms. Different electromagnetic transient real-time digital simulators are used to simulate the SPS, to which protection is provided through the relay modeled in dSPACE. Simulation results from these three HIL platforms demonstrate that the proposed overcurrent relay model was successfully modeled, simulated and tested using various tools for model-based design. Testing results show that the developed model can work with different real-time platforms, and that in contrast to a commercial relay, the developed relay model has increased flexibility because settings such as reclose delay and pickup value can be changed online. This feature can be used to develop an advanced relay model with a dynamic pickup value. An advanced relay model will be useful for the SPS, because such system is subject to topological changes and reconfiguration that are not as prevalent in other types of power systems.

The invention of the telephone and the telegraph opened the door to worldwide corrmunications. Over the years, complex and versatile corrmunication systems have evolved involving many devices and technologies. Switching protocols between switching offices have been established in accordance with the nature of the machines and with the capabilities of the transmission medium and its environment. Switching systems are now stored program oriented, providing a more generalized and digitally oriented internal switching capability. This report will discuss the Time Slot Interchange ( TSI), an important component of the Digital Central Office (DCO). The operation of the send section and the receive section and their relationship to the port group highways and cross office highways are presented in detail. The various TSI corrmands for performing the necessary operations are discussed. The TSI considered is that designed by Stromberg-Carlson, and future design trends in the design are presented.

This research analyzes the linkage between power system disturbances and failures in relaying systems. The annual disturbance reports prepared by the North American Electric Reliability Council were examined. It has been found that relaying system failures plays very important role in power system cascading outages. The type of relaying system failures that are the most troublesome are the ones that have a potential to remain hidden until being exposed by some abnormal power system states to trigger relay misoperations. Each commonly used relaying scheme in transmission system is examined for any hidden failures that can lead to relay misoperations and multiple power system contingencies. Each hidden failure mode has a region, called region of vulnerability. Inside this region, some abnormal power system states can expose the hidden failure. The reach of the region depends largely on the settings of the relay in question. A method of computing the relative importance of each region of vulnerability, called vulnerability index, was proposed. The calculation of the index can be based on some measurements of power system performances. In this research, the stability measurements of the system following some contingencies that may occur in the region are chosen. With this approach, vulnerable relays can be identified. A preventive method was proposed so that the number of relay misoperations due to hidden failures and, ultimately, the number of power system disturbances can be reduced. / Ph. D.