published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

Automated fault location systems use power quality monitoring and circuit data to provide with a distance or impedance estimate to the fault. This can be used to avoid manual patrolling of the entire feeder in case of a main feeder lockout. It can also be used for circuits with repeated momentary interruptions to pinpoint the section of the circuit causing such problems. Self clearing sub cycle faults have been identified as the precursors of a number of sustained faults (requiring the operation of protective device) in utility distribution networks. The frequency of such incipient faults increases considerably as they are about to evolve into a full blown fault. This report proposes a modified and improved fault location algorithm that can be used to accurately identify sustained as well as temporary faults. The algorithm is based in the time domain and takes into account the arc voltage during a fault event. The proposed algorithm is developed, validated and applied to known distribution field data. Time domain simulation models are also used for validation purposes. The developed algorithm was observed to be very accurate when compared to other impedance based fault location algorithms proposed in the literature. Finally, sub cycle event identification and fault pre-location is proposed that can be very useful for electric utility operations. Highly accurate results were observed during this application study. For instance, a current waveform containing three incipient and one full fault event is shown in the figure given below. The estimated reactance to an incipient fault location is approximately 1.1 Ω. The fault location results obtained from the first three sub-cycle faults can be used to avert the final sustained fault event. / text

Compared with conventional measurements from supervisory control and data acquisition (SCADA) system, phasor measurement units (PMUs) provide time-synchronized and direct measurements of phasors. The availability of synchronized phasor measurements can significantly improve power system protection and analysis. This dissertation is specifically committed to using synchronized measurements for estimation of fault locations in transmission systems. Transmission lines are prone to various short-circuit faults. Accurate fault location is critical for rapid power recovery. Chapter 2 proposes a new fault location method based on sparse wide area measurements. One distinguishing feature of this method is its applicability to both transposed and untransposed transmission lines. In addition, the method is developed based on sparse-wide area measurement that may be taken far away from the faulted line. Shunt capacitances of transmission lines are also fully considered by the algorithm. Moreover, when synchronized measurements from multiple buses are available, an optimal estimator can be used to make the most use of measurements, and to detect and identify potential bad measurements. Most of the existing fault location literatures discuss common shunt faults, including single line-to-ground faults, line-to-line faults, line-to-line-to-ground faults, and three-phase faults. However, in addition to common shunt faults, some complex faults may also occur in power systems. Among these complex faults, evolving fault and inter-circuit fault are two typical examples. Chapter 3 extends the method developed in Chapter 2 to deal with evolving faults. The proposed wide-area fault location methods are immune to fault type evolution, and are applicable to both transposed and untransposed lines. Chapter 4 discusses location of inter-circuit faults. Inter-circuit fault is a type of simultaneous fault, and it is the most common simultaneous fault type. Inter-circuit faults between each circuit in a double-circuit line is the most common inter-circuit fault. A fault location method for inter-circuit faults on double-circuit lines are developed and evaluated in Chapter 4. Chapter 5 puts forward a fault location algorithm, which does not require line parameters information, for series-compensated transmission lines. Two-end synchronized voltage and current measurements are utilized. The proposed method is independent of source impedance and fully considers shunt capacitances of transmission lines.

La compétitivité des entreprises manufacturières dépend fortement de la productivité des machines etdes moyens de production. Pour garantir un haut niveau de productivité il est indispensable de minimiser lestemps d'arrêt dus aux fautes ou dysfonctionnements. Cela nécessite des méthodes efficaces pour détecter et isolerles fautes apparues dans un système (FDI). Dans cette thèse, une méthode FDI à base de modèles est proposée.La méthode est conçue pour la classe des systèmes à événements discrets industriels composés d’une bouclefermée du contrôleur et du processus. En comparant les comportements observés et attendus par le modèle, il estpossible de détecter et d’isoler des fautes. A la différence de la plupart des approches FDI des systèmes àévénements discrets, une méthode basée sur des modèles du comportement normal au lieu de modèles descomportements fautifs est proposée. Inspiré par le concept des résidus bien connu pour le diagnostic dessystèmes continus, une nouvelle approche pour l’isolation des fautes dans les systèmes à événements discrets aété développée. La clé pour l’application des méthodes FDI basées sur des modèles est d’avoir un modèle justedu système considéré. Comme une modélisation manuelle peut être très laborieuse et coûteuse pour dessystèmes à l’échelle industrielle, une approche d’identification pour les systèmes à événements discrets enboucle fermée est développée. Basée sur un algorithme connu pour l’identification des modèles monolithiques,une adaptation distribuée est proposée. Elle permet de traiter de grands systèmes comportant un haut degré deparallélisme. La base de cette approche est une décomposition du système en sous systèmes. Cettedécomposition est automatisée en utilisant un algorithme d’optimisation analysant le comportement observé dusystème. Les méthodes conçues dans cette thèse ont été mises en oeuvre sur une étude de cas et sur uneapplication d’échelle industrielle. / The competitiveness of manufacturing companies strongly depends on the productivity of machinesand production processes. To guarantee a high level of productivity, downtimes occurring due to faults have tobe kept as short as possible. This necessitates efficient fault detection and isolation (FDI) methods. In this work,a model-based FDI method for the widely used class of industrial closed-loop Discrete Event Systems isproposed. The considered systems consist of the closed-loop of plant and controller. Based on the comparison ofobserved and modeled system behavior, it is possible to detect and to isolate faults. Unlike most known methodsfor FDI in Discrete Event Systems, this work proposes working with a model of the fault-free behavior ratherthan working fault models. Inspired by the concept of residuals known from FDI in continuous systems, a newapproach for fault isolation based on fault-free Discrete Event System models is developed. The key of anymodel-based diagnosis method is to have an accurate model of the considered system. Since manual modelbuildingcan be very difficult for large industrial systems, an identification approach for this class of systems isintroduced. Based on an already existing monolithic identification algorithm, a distributed adaptation isdeveloped which allows treating large, concurrent systems. The key of the proposed approach is an automaticdecomposition of a given closed-loop Discrete Event System using an optimization approach which analyzesobserved system behavior. The methods developed in this thesis are applied to a mid-sized laboratory system andto an industrial winder to show their scalability.

Este trabalho apresenta o desenvolvimento de algoritmos para determinação da estimativa da distância de ocorrência de falta em uma linha de transmissão de alta tensão, em relação a um terminal local, e também a classificação do tipo de falta, utilizando técnicas baseadas em redes neurais artificiais. Os testes e a validação dos algoritmos propostos são feitos a partir de dados simulados para os fasores de tensão e corrente, em regime permanente, com uso da linguagem MATLAB. Os fasores são obtidos com uso de cálculo tradicional de curto e parâmetros reais de uma linha de transmissão conhecida. Em casos reais os fasores seriam obtidos de amostras de tensões e correntes detectadas por dispositivos de proteção localizados nos terminais local e remoto da linha de transmissão em análise. As simulações das redes neurais para a classificação do tipo de falta e para a obtenção da estimativa da distância de falta foram feitas com duas rotinas escritas em MATLAB levando em consideração erros de medição dos fasores. Os resultados obtidos permitem avaliar a eficiência e a precisão dos algoritmos propostos em relação aos já existentes e conhecidos na literatura, e que usam somente equacionamento elétrico. / This work presents the development of algorithms for determination of the estimate of the distance of occurrence of fault in a high voltage transmission line, in relation to a local terminal, and also the classification of the fault type, using techniques based on artificial neural networks. The tests and the validation of the proposed algorithms are made using simulated data for the voltage and current phasors, in steady state, with use of the MATLAB language. The phasors are obtained with use of traditional calculation of short-circuit and real parameters of a known transmission line. In real cases the phasors would be obtained with samples of voltages and currents detected by protection devices located in the local and remote terminals of the transmission line in analysis. The simulations of the neural networks for the classification of the fault type and for the obtaining the estimate of the fault distance were done with two routines written in MATLAB taking into account measurement errors of the phasors. The obtained results allow to evaluate the efficiency and the accuracy of the proposed algorithms in relation to the already existent and known in the literature, and that use only electric equations.

by Chi-kwong Fong. / Thesis (M.Sc.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 30-[31]). / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Data Capture Subsystem --- p.7 / Chapter 3 --- Anomaly Detection Subsystem --- p.10 / Chapter 4 --- Descriptive Language Translation System --- p.14 / Chapter 5 --- Rule-based Analysis Subsystem --- p.20 / Chapter 6 --- Testing Results --- p.22 / Chapter 7 --- Summary --- p.27 / Bibliography --- p.30

Este documento apresenta uma metodologia analítica adaptativa para localização de faltas baseada na estimativa da impedância para sistemas de distribuição ativos. A metodologia proposta combina a informação fornecida por dispositivos eletrônicos inteligentes alocados na subestação principal e nos terminais de cada unidade de Recurso Energético Distribuído (do inglês Distributed Energy Resources - DER), o conhecimento da topologia da rede e os seus parâmetros para estimar a localização da falta. A característica adaptativa é dada pelo uso de modelos elétricos lineares para considerar o efeito das DER conectadas à rede, quando a informação fornecida pelos Dispositivos Eletrônicos Inteligentes (do inglês Intelligent Electronic Devices - IED) não é disponível. Adicionalmente, uma estratégia baseada na técnica Ladder é desenvolvida para estimar a contribuição de corrente desde as DER até o ponto de falta. Esta estratégia permite considerar vários geradores conectados e seus diferentes modos de operação. A metodologia proposta foi validada com o sistema IEEE 34 barras. Este sistema foi modelado no Alternative Transients Program (ATP) e modificado pela inserção de várias unidades DER. A metodologia proposta foi validada em vários cenários. Estes cenários avaliam o efeito da distância até a falta, resistência da falta, incerteza na carga, nível de penetração de DER, número de geradores conectados e erros nas medidas ou na estimação dos parâmetros das DER quando seus modelos forem utilizados. Para estas considerações, o desempenho da formulação proposta é satisfatório, apresentando erros menores do que 3%. / This document presents an adaptive analytical impedance-based fault location methodology for active distribution systems. The proposal combines information provided by Intelligent Electronic Devices (IEDs) located in the substation, each Distributed Energy Resources units terminal, the knowledge of the network topology as well as its parameters to estimate the fault location. Its adaptive feature is given by the use of linear analytical equivalent models to consider of DER effect in case the information provided by a local IED is not available. Additionally, a ladder-based technique is proposed to estimate the current contribution from of DER to the fault point. This process allows considering several DER connected and their different operation modes. The proposed methodology is validated on the IEEE 34-node test feeder. This system is modeled on ATP/EMTP and modified with the insertion of several DER units. The methodology is validated by considering several scenarios. These scenarios evaluate the effect of fault distance, fault resistance, load variation, DER penetration level, numbers of DERs connected and errors in the DER parameters. For these considerations, the proposed methodology performance is satisfactory, presenting fault location errors below 3%.

Este trabalho tem como objetivo estudar e propor métodos de teste funcional visando a detecção e localização de falhas na infra-estrutura das redes-em-chip. Para isso, o trabalho apresenta, inicialmente, uma descrição das principais características das redes-em-chip, explicando o que elas são e para que elas servem. Em seguida são apresentados conceitos de teste de circuitos integrados, bem como trabalhos relacionados ao teste das redes-em-chip. Um método de teste visando a detecção de falhas nas interconexões de dados de uma NoC é apresentado no trabalho, sendo este método posteriormente estendido para incluir as interconexões de controle. Os circuitos de teste necessários para implementar a estratégia de teste proposta também são descritos. A partir do método de teste apresentado, é feito um estudo sobre sua capacidade de localização de falhas, onde alterações visando o aumento dessa capacidade de localização de falhas são propostas. Por fim o método de teste é estendido para detecção de falhas nos roteadores da rede. / The purpose of this work is to study and propose functional test methods that aim the detection and location of faults in the NoC’s infrastructure. In order to do so, this work presents, initially, a description of the main characteristics of networks-on-chip, explaining what are NoCs and what is their purpose. Fallowing this description, some concepts related to the test of integrated circuits are presented as well as related works on NoC testing. A method aiming the detection of data interconnect faults in a NoC is presented in this work. This method is later extended to include faults in the control interconnections as well. The circuits used to implement the proposed strategy are also described here. Based on the proposed test strategy, the method’s capability to locate faults is studied. Changes are proposed to the test method in order to increase this fault location capability. Finally, the test method is extended to include faults inside the router’s logic.

by Arion Ko Kin Wa. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 101-[106]). / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Overview --- p.1 / Chapter 1.2 --- Service Survivability Planning --- p.2 / Chapter 1.3 --- Categories of Outages --- p.3 / Chapter 1.4 --- Goals of Restoration --- p.4 / Chapter 1.5 --- Technology Impacts on Network Survivability --- p.5 / Chapter 1.6 --- Performance Models and Measures in Quantifying Network Sur- vivability --- p.6 / Chapter 1.7 --- Organization of Thesis --- p.6 / Chapter 2 --- Design and Implementation of A Survivable High-Speed Mul- timedia Network --- p.8 / Chapter 2.1 --- An Overview of CUM LAUDE NET --- p.8 / Chapter 2.2 --- The Network Architecture --- p.9 / Chapter 2.2.1 --- Architectural Overview --- p.9 / Chapter 2.2.2 --- Router-Node Design --- p.11 / Chapter 2.2.3 --- Buffer Allocation --- p.12 / Chapter 2.2.4 --- Buffer Transmission Priority --- p.14 / Chapter 2.2.5 --- Congestion Control --- p.15 / Chapter 2.3 --- Protocols --- p.16 / Chapter 2.3.1 --- Design Overview --- p.16 / Chapter 2.3.2 --- ACTA - The MAC Protocol --- p.17 / Chapter 2.3.3 --- Protocol Layering --- p.18 / Chapter 2.3.4 --- "Segment, Datagram and Packet Format" --- p.20 / Chapter 2.3.5 --- Fast Packet Routing --- p.22 / Chapter 2.3.6 --- Local Host NIU --- p.24 / Chapter 2.4 --- The Network Restoration Strategy --- p.25 / Chapter 2.4.1 --- The Dual-Ring Model and Assumptions --- p.26 / Chapter 2.4.2 --- Scenarios of Network Failure and Remedies --- p.26 / Chapter 2.4.3 --- Distributed Fault-Tolerant Algorithm --- p.26 / Chapter 2.4.4 --- Distributed Auto-Healing Algorithm --- p.28 / Chapter 2.4.5 --- The Network Management Signals --- p.31 / Chapter 2.5 --- Performance Evaluation --- p.32 / Chapter 2.5.1 --- Restoration Time --- p.32 / Chapter 2.5.2 --- Reliability Measures --- p.34 / Chapter 2.5.3 --- Network Availability During Restoration --- p.41 / Chapter 2.6 --- The Prototype --- p.42 / Chapter 2.7 --- Technical Problems Encountered --- p.45 / Chapter 2.8 --- Chapter Summary and Future Development --- p.46 / Chapter 3 --- A Simple Experimental Network Management Software - NET- MAN --- p.48 / Chapter 3.1 --- Introduction to NETMAN --- p.48 / Chapter 3.2 --- Network Management Basics --- p.49 / Chapter 3.2.1 --- The Level of Management Protocols --- p.49 / Chapter 3.2.2 --- Architecture Model --- p.51 / Chapter 3.2.3 --- TCP/IP Network Management Protocol Architecture --- p.53 / Chapter 3.2.4 --- A Standard Network Management Protocol On Internet - SNMP --- p.54 / Chapter 3.2.5 --- A Standard For Managed Information --- p.55 / Chapter 3.3 --- The CUM LAUDE Network Management Protocol Suite (CNMPS) --- p.56 / Chapter 3.3.1 --- The Architecture --- p.53 / Chapter 3.3.2 --- Goals of the CNMPS --- p.59 / Chapter 3.4 --- Highlights of NETMAN --- p.61 / Chapter 3.5 --- Functional Descriptions of NETMAN --- p.63 / Chapter 3.5.1 --- Topology Menu --- p.64 / Chapter 3.5.2 --- Fault Manager Menu --- p.65 / Chapter 3.5.3 --- Performance Meter Menu --- p.65 / Chapter 3.5.4 --- Gateway Utility Menu --- p.67 / Chapter 3.5.5 --- Tools Menu --- p.67 / Chapter 3.5.6 --- Help Menu --- p.68 / Chapter 3.6 --- Chapter Summary --- p.68 / Chapter 4 --- A Local Map Based (LMB) Self-Healing Scheme for Arbitrary Topology Networks --- p.70 / Chapter 4.1 --- Introduction --- p.79 / Chapter 4.2 --- An Overview of Existing DCS-Based Restoration Algorithms --- p.72 / Chapter 4.3 --- The Network Model and Assumptions --- p.74 / Chapter 4.4 --- Basics of the LMB Scheme --- p.75 / Chapter 4.4.1 --- Restoration Concepts --- p.75 / Chapter 4.4.2 --- Terminology --- p.76 / Chapter 4.4.3 --- Algorithm Parameters --- p.77 / Chapter 4.5 --- Performance Assessments --- p.78 / Chapter 4.6 --- The LMB Network Restoration Scheme --- p.80 / Chapter 4.6.1 --- Initialization - Local Map Building --- p.80 / Chapter 4.6.2 --- The LMB Restoration Messages Set --- p.81 / Chapter 4.6.3 --- Phase I - Local Map Update Phase --- p.81 / Chapter 4.6.4 --- Phase II - Update Acknowledgment Phase --- p.82 / Chapter 4.6.5 --- Phase III - Restoration and Confirmation Phase --- p.83 / Chapter 4.6.6 --- Phase IV - Cancellation Phase --- p.83 / Chapter 4.6.7 --- Re-Initialization --- p.84 / Chapter 4.6.8 --- Path Route Monitoring --- p.84 / Chapter 4.7 --- Performance Evaluation --- p.84 / Chapter 4.7.1 --- The Testbeds --- p.84 / Chapter 4.7.2 --- Simulation Results --- p.86 / Chapter 4.7.3 --- Storage Requirements --- p.89 / Chapter 4.8 --- The LMB Scheme on ATM and SONET environment --- p.92 / Chapter 4.9 --- Future Work --- p.94 / Chapter 4.10 --- Chapter Summary --- p.94 / Chapter 5 --- Conclusion and Future Work --- p.96 / Chapter 5.1 --- Conclusion --- p.95 / Chapter 5.2 --- Future Work --- p.99 / Bibliography --- p.101 / Chapter A --- Derivation of Communicative Probability --- p.107 / Chapter B --- List of Publications --- p.110

Este trabalho apresenta o desenvolvimento de algoritmos para determinação da estimativa da distância de ocorrência de falta em uma linha de transmissão de alta tensão, em relação a um terminal local, e também a classificação do tipo de falta, utilizando técnicas baseadas em redes neurais artificiais. Os testes e a validação dos algoritmos propostos são feitos a partir de dados simulados para os fasores de tensão e corrente, em regime permanente, com uso da linguagem MATLAB. Os fasores são obtidos com uso de cálculo tradicional de curto e parâmetros reais de uma linha de transmissão conhecida. Em casos reais os fasores seriam obtidos de amostras de tensões e correntes detectadas por dispositivos de proteção localizados nos terminais local e remoto da linha de transmissão em análise. As simulações das redes neurais para a classificação do tipo de falta e para a obtenção da estimativa da distância de falta foram feitas com duas rotinas escritas em MATLAB levando em consideração erros de medição dos fasores. Os resultados obtidos permitem avaliar a eficiência e a precisão dos algoritmos propostos em relação aos já existentes e conhecidos na literatura, e que usam somente equacionamento elétrico. / This work presents the development of algorithms for determination of the estimate of the distance of occurrence of fault in a high voltage transmission line, in relation to a local terminal, and also the classification of the fault type, using techniques based on artificial neural networks. The tests and the validation of the proposed algorithms are made using simulated data for the voltage and current phasors, in steady state, with use of the MATLAB language. The phasors are obtained with use of traditional calculation of short-circuit and real parameters of a known transmission line. In real cases the phasors would be obtained with samples of voltages and currents detected by protection devices located in the local and remote terminals of the transmission line in analysis. The simulations of the neural networks for the classification of the fault type and for the obtaining the estimate of the fault distance were done with two routines written in MATLAB taking into account measurement errors of the phasors. The obtained results allow to evaluate the efficiency and the accuracy of the proposed algorithms in relation to the already existent and known in the literature, and that use only electric equations.