To see the other types of publications on this topic, follow the link: Fault analysis/power systems.
Dissertations / Theses on the topic 'Fault analysis/power systems'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Fault analysis/power systems.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Yang, Jin. "Fault analysis and protection for wind power generation systems." Thesis, University of Glasgow, 2011. http://theses.gla.ac.uk/2420/.
Full textAbstract:
Wind power is growing rapidly around the world as a means of dealing with the world energy shortage and associated environmental problems. Ambitious plans concerning renewable energy applications around European countries require a reliable yet economic system to generate, collect and transmit electrical power from renewable resources. In populous Europe, collective offshore large-scale wind farms are efficient and have the potential to reach this sustainable goal. This means that an even more reliable collection and transmission system is sought. However, this relatively new area of offshore wind power generation lacks systematic fault transient analysis and operational experience to enhance further development. At the same time, appropriate fault protection schemes are required. This thesis focuses on the analysis of fault conditions and investigates effective fault ride-through and protection schemes in the electrical systems of wind farms, for both small-scale land and large-scale offshore systems. Two variable-speed generation systems are considered: doubly-fed induction generators (DFIGs) and permanent magnet synchronous generators (PMSGs) because of their popularity nowadays for wind turbines scaling to several-MW systems. The main content of the thesis is as follows. The protection issues of DFIGs are discussed, with a novel protection scheme proposed. Then the analysis of protection scheme options for the fully rated converter, direct-driven PMSGs are examined and performed with simulation comparisons. Further, the protection schemes for wind farm collection and transmission systems are studied in terms of voltage level, collection level wind farm collection grids and high-voltage transmission systems for multi-terminal DC connected transmission systems, the so-called “Supergrid”. Throughout the thesis, theoretical analyses of fault transient performances are detailed with PSCAD/EMTDC simulation results for verification. Finally, the economic aspect for possible redundant design of wind farm electrical systems is investigated based on operational and economic statistics from an example wind farm project.
2
Ahmed, Sara Mohamed. "Computer Modeling and Simulation of Power Electronics Systems for Stability Analysis." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/31026.
Full textAbstract:
This works focuses on analyzing ac/dc hybrid power systems with large number of power converters that can be used for a variety of applications. A computer model of a sample power system is developed. The system consists of various detailed/switching models that are connected together to study the sample system dynamic behavior and to set conditions for safe operation. The stability analysis of this type of power systems has been approached using time domain simulations. There are three types of stability analysis that are studied: steady-state, small-signal analysis and large signal analysis. The steady-state stability analysis is done by investigating the nominal operation of the power electronics system proposed. The small-signal stability of this system is studied by running different parametric case studies. First, the safe values of the main system parameters are defined from the view of the stability of the complete system. Then, these different critical parameters of the system are mapped together to predict their influence on the system. The large signal stability is examined through the response of the power system to different types of transient changes. There are different load steps applied to the critical parameters of the system at the maximum or minimum stability boundary limit found by the mapping section. The maximum load step after which the system can recover and remain stable is defined. The other type of large signal stability analysis done is the study of faults. There are different faults to be studied; for example, over voltage, under voltage and over current.Master of Science
3
Wong, Kwok-Tung. "A generalised transients program for power system protection studies." Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330295.
Full text
4
Brockhoeft, Tetiana. "Educational Modeling for Fault Analysis of Power Systems with STATCOM Controllers using Simulink." ScholarWorks@UNO, 2014. http://scholarworks.uno.edu/td/1906.
Full textAbstract:
The analysis of power systems under fault condition represents one of the most important and complex tasks in power engineering. The study and detection of these faults are necessary to ensure that the reliability and stability of the power system do not suffer a decrement as a result of a critical event such as fault. The purpose of this thesis is to develop and to present an educational tool for students to model FACTS devices using Simulink. Furthermore, the development of this thesis provides the means for students to model different types of faults. The development is based on presenting a power system – the Test System - by its simplest form including generation, transmission, transformers, loads and STATCOM device as an example of the general FACTS devices. The thesis includes modeling of the Test System using Simulink and MATLAB program to produce the results for further analysis. The findings and development included in the thesis is intended to serve as an educational tool for students interested in the study of faults and their impact on FACTS devices. Students may use the thesis as the building block for developing models of larger and more complex power systems using Simulink and MATLAB programs for further study of impacts of FACTS devices in power systems.
5
McDonald, John D. F. "Investigations into the design of Powerformer for optimal generator and system performance under fault conditions /." [St. Lucia, Qld], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18316.pdf.
Full text
6
Minkley, Warick. "Analysis of restricted earth fault relay application within a shunt capacitor bank design impacting on protection stability." Thesis, Nelson Mandela Metropolitan University, 2013. http://hdl.handle.net/10948/d1021106.
Full textAbstract:
This research is aimed at analyzing the performance of the restricted earth fault relay used on a 400kV capacitor bank scheme used on the Eskom Transmission network. After the commissioning of two Capacitor Banks using the above mentioned scheme design the plant was energized. As a result of the energization the Shunt Capacitor Bank (SCB) then experienced spurious trips. The cause of the trips was found to be the operation of the restricted earth fault relay. In this research project, restricted earth fault protection on SCBs in the Eskom Transmission environment will be the area of interest. The proposed research will analyze the current SCB protection scheme in service specifically looking at the restricted earth fault circuit design and relay performance. An equivalent model of the SCB from primary plant perspective based on theory will be derived. Recording and analyzing of Comtrade transient waveforms respectively, when the bank is nergized, will be done in order to provide a reference base to work from. Manual alculations of various parameters from the derived model including transient inrush currents and fault currents will be performed to access applicable scheme parameters. Further calculations will include the voltage setting for the restricted earth fault relay. As a result of the analysis a recommendation will be made on a viable solution or a revised design will be put forward, based on the results, to improve the scheme’s performance. The protection scheme is used on the two 400kV 100MVAR capacitor banks 11 and 12 at Hydra Substation.
7
Blair, Steven M. "The analysis and application of resistive superconducting fault current limiters in present and fututre power systems." Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=19008.
Full textAbstract:
Fault current levels in electrical systems are rising due to natural growth in demand, the increasing presence of distributed generation (DG), and increased network interconnection. This rising trend is expected to continue in the future. Marine vessel power systems are highly power-dense and are often safety-critical. Power system protection is increasingly challenging in these systems. Superconducting fault current limiters (SFCLs) o er an attractive solution to many of the issues faced. This thesis establishes and reviews the state of the art in resistive SFCL technology and application knowledge, and provides crucial research-based guidance for the adoption of resistive SFCLs in future power systems. The issues associated with the application of resistive SFCLs- including location, resistance rating, the recovery period, and interaction with protection systems are demonstrated. The relationship between several resistive SFCL design parameters is established using a gener ic analytical approach, hence providing a framework for validating SFCL designs. In particular, it is shown that a particular SFCL resistance rating leads to a peak in the superconductor energy dissipation, which generally should be avoided. It is proven that resistive SFCLs have an inverse current-time characteristic, i.e., they will operate in a time that inversely depends upon the initial fault current magnitude. This knowledge is critical for underpinning the operation of a novel protection scheme using multiple resistive SFCLs. The scheme offers several advantages: very fast-acting operation in response to faults anywhere on the system under study; maximum prospective fault currents are prevented from occurring, reducing the duty on circuit breakers; inherent, fast-acting backup; and communications is not required. It is shown that the scheme is suited to highly-interconnected systems with a high presence of DG. The scheme is readily applicable to the design of future utility and marine vessel power systems.
8
Luo, Xu. "Power system fault analysis based on intelligent techniques and intelligent electronic device data." Texas A&M University, 2003. http://hdl.handle.net/1969.1/5797.
Full textAbstract:
This dissertation has focused on automated power system fault analysis. New
contributions to fault section estimation, protection system performance evaluation
and power system/protection system interactive simulation have been achieved. Intelligent techniques including expert systems, fuzzy logic and Petri-nets, as well as
data from remote terminal units (RTUs) of supervisory control and data acquisition
(SCADA) systems, and digital protective relays have been explored and utilized to
fufill the objectives.
The task of fault section estimation is difficult when multiple faults, failures
of protection devices, and false data are involved. A Fuzzy Reasoning Petri-nets
approach has been proposed to tackle the complexities. In this approach, the fuzzy
reasoning starting from protection system status data and ending with estimation of
faulted power system section is formulated by Petri-nets. The reasoning process is
implemented by matrix operations. Data from RTUs of SCADA systems and digital
protective relays are used as inputs. Experiential tests have shown that the proposed
approach is able to perform accurate fault section estimation under complex scenarios.
The evaluation of protection system performance involves issues of data acquisition, prediction of expected operations, identification of unexpected operations and
diagnosis of the reasons for unexpected operations. An automated protection system performance evaluation application has been developed to accomplish all the tasks. The application automatically retrieves relay files, processes relay file data,
and performs rule-based analysis. Forward chaining reasoning is used for prediction
of expected protection operation while backward chaining reasoning is used for diagnosis of unexpected protection operations. Lab tests have shown that the developed
application has successfully performed relay performance analysis.
The challenge of power system/protection system interactive simulation lies in
modeling of sophisticated protection systems and interfacing the protection system
model and power system network model seamlessly. An approach which utilizes the
"compiled foreign model" mechanism of ATP MODELS language is proposed to model
multifunctional digital protective relays in C++ language and seamlessly interface
them to the power system network model. The developed simulation environment
has been successfully used for the studies of fault section estimation and protection
system performance evaluation.
9
BONFIETTI, GERSON. "Analise da confiabilidade do sistema de suprimento de energia eletrica de emergencia de um reator nuclear de pequeno porte." reponame:Repositório Institucional do IPEN, 2003. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11129.
Full textAbstract:
Made available in DSpace on 2014-10-09T12:48:42Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T13:58:03Z (GMT). No. of bitstreams: 1 09246.pdf: 5265828 bytes, checksum: 4d1524b4005b3c1696584a11c7c97252 (MD5)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
10
Al-Atrash, Hussam. "ANALYSIS AND DESIGN OF A MODULAR SOLAR-FED FAULT-TOLERANT POWER SYSTEM WITH MAXIMUM POWER POINT TRACKING." Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2572.
Full textAbstract:
Solar power is becoming ever more popular in a variety of applications. It is particularly attractive because of its abundance, renewability, and environment friendliness. Solar powered spacecraft systems have ever-expanding loads with stringent power regulation specifications. Moreover, they require a light and compact design of their power system. These constraints make the optimization of power harvest from solar arrays a critical task. Florida Power Electronics Center (FPEC) at UCF set to develop a modular fault-tolerant power system architecture for space applications. This architecture provides a number of very attractive features including Maximum Power Point Tracking (MPPT) and uniform power stress distribution across the system. MPPT is a control technique that leads the system to operate its solar sources at the point where they provide maximum power. This point constantly moves following changes in ambient operating conditions. A digital controller is setup to locate it in real time while optimizing other operating parameters. This control scheme can increase the energy yield of the system by up to 45%, and thus significantly reduces the size and weight of the designed system. The modularity of the system makes it easy to prototype and expand. It boosts its reliability and allows on-line reconfiguration and maintenance, thus reducing down-time upon faults. This thesis targets the analysis and optimization of this architecture. A new modeling technique is introduced for MPPT in practical environments, and a novel digital power stress distribution scheme is proposed in order to properly distribute peak and thermal stress and improve reliability. A 2kW four-channel prototype of the system was built and tested. Experimental results confirm the theoretical improvements, and promise great success in the field.M.S.E.E.
Department of Electrical and Computer Engineering
Engineering and Computer Science
Electrical Engineering
11
Dieker, Joseph. "High impedance fault location identification using Bayesian analysis in a shipboard power system." Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/14643.
Full textAbstract:
Master of ScienceDepartment of Electrical and Computer Engineering
Sanjoy Das
Noel Schulz
In a shipboard power system (SPS) there are many possible locations for faults along power lines. It is important to identify the location and isolate these faults in order to protect the equipment and loads. The shipboard systems represented in this research are based on an all-electric ship that is presented by Corzine and a simplified version of the same ship. This research considers faults at the ends on the lines. Sensors collect data in order to determine where the fault has occurred. The fault location identification algorithm being presented uses data collected from simulations of different switch configurations and different loads. After the data is collected, Bayesian techniques are used to determine where the fault is located. An online training technique is presented to adjust to changes in loads over time to increase the accuracy of the algorithm.
12
Souto, Laiz. "Data-driven approaches for event detection, fault location, resilience assessment, and enhancements in power systems." Doctoral thesis, Universitat de Girona, 2021. http://hdl.handle.net/10803/671402.
Full textAbstract:
This thesis presents the study and development of distinct data-driven techniques to support event detection, fault location, and resilience assessment towards enhancements in power systems. It is divided in three main parts as follows. The first part investigates improvements in power system monitoring and event detection methods with focus on dimensionality reduction techniques in wide-area monitoring systems. The second part focuses on contributions to fault location tasks in power distribution networks, relying on information about the network topology and its electrical parameters for short-circuit simulations over a range of scenarios. The third part assesses enhancements in power system resilience to high-impact, lowprobability events associated with extreme weather conditions and human-made attacks, relying on information about the system topology combined with simulations of representative scenarios for impact assessment and mitigation. Overall, the proposed data-driven algorithms contribute to event detection, fault location, and resilience assessment, relying on electrical measurements recorded by intelligent electronic devices, historical data of past events, and representative scenarios, together with information about the network topology, electrical parameters, and operating status. The validation of the algorithms, implemented in MATLAB, is based on computer simulations using network models implemented in OpenDSS and SimulinkEsta tesis presenta el estudio y el desarrollo de distintas técnicas basadas en datos para respaldar las tareas de detección de eventos, localización de fallos y resiliencia hacia mejoras en sistemas de energía eléctrica. Los contenidos se dividen en tres partes principales descritas a continuación. La primera parte investiga mejoras en el monitoreo de sistemas de energía eléctrica y métodos de detección de eventos con enfoque en técnicas de reducción de dimensionalidad en wide-area monitoring systems. La segunda parte se centra en contribuciones a tareas de localización de fallos en redes eléctricas de distribución, basándose en información acerca de la topología de la red y sus parámetros eléctricos para simulaciones de cortocircuito en una variedad de escenarios. La tercera parte evalúa mejoras en la resiliencia de sistemas de energía eléctrica ante eventos de alto impacto y baja probabilidad asociados con condiciones climáticas extremas y ataques provocados por humanos, basándose en información sobre la topología del sistema combinada con simulaciones de escenarios representativos para la evaluación y mitigación del impacto. En general, los algoritmos propuestos basados en datos contribuyen a la detección de eventos, la localización de fallos, y el aumento de la resiliencia de sistemas de energía eléctrica, basándose en mediciones eléctricas registradas por dispositivos electrónicos inteligentes, datos históricos de eventos pasados y escenarios representativos, en conjunto con información acerca de la topología de la red, parámetros eléctricos y estado operativo. La validación de los algoritmos, implementados en MATLAB, se basa en simulaciones computacionales utilizando modelos de red implementados en OpenDSS y Simulink
13
Vichis-Rodriguez, Damian Sergio. "Modelling of three phase AC machines suitable for internal fault simulation, detection and analysis in multi-machine power systems." Thesis, University of Glasgow, 2010. http://theses.gla.ac.uk/1782/.
Full textAbstract:
The ever increasing demand for electrical energy has meant that electrical power systems have evolved to be the highly complex networks that are in existence today, where the transient interactions that take place between large synchronous generators have been the focus of advanced research for many decades. More recently, the proliferation of synchronous and asynchronous generators of comparatively small rating, which are not centrally planned, has added new impetus to this area of research. At a time when not only technical but also economic and environmental concerns must be carefully assessed, more realistic models of the individual power plant transient response and its interaction with the rest of the network become mandatory to achieve more accurate analysis of the network operation and prevent wastage of technical and economical resources. The main thrust of this research project is to develop comprehensive models of rotating machinery with which to assess the transient response of electrical power networks that undergo severe unbalanced operation due to faulty conditions developing anywhere in the power network, including the rotating machinery’s windings. To achieve an unrivalled speed of response, a nodal-based model of the electrical power network has been developed, enabling the study of power networks of any size and topological formation with the utmost flexibility and efficiency. The rotating machinery addressed in this research work is the three-phase synchronous generator and the three-phase asynchronous (induction) machine. In multi-machine power systems transient studies, it is common to look at all the rotating machinery in the network as being healthy units having an idealized sinusoidally distributed stator winding – the possibility of a severe unbalanced condition internal to the machine due to internal fault or the effect of space harmonics, has, so far, not been addressed in a multi-machine environment. In this research work, new EMTP type models, with enhanced numerical properties, are constructed for the simulation of internal and external machine fault phenomena with different levels of details including the effects of saturation and space harmonics. Advanced numerical methods are employed to improve on the numerical stability of the network model allowing the use of larger time steps than what otherwise is possible with traditional numerical methods, enabling the new model to execute faster than existing models and yet to exhibit the same degree of numerical accuracy with an unrivalled degree of modelling flexibility. A case in point is an application made to model the transient response of a Variable Frequency Transformer (VFT) undergoing internal faults on its stator side. The rotating machinery models with internal fault representation developed in this research lend themselves to an application in the area of condition monitoring, where a new method is developed to detect internal faults in the stator side of three phase rotating machinery. The method is shown to be highly effective when applied to machines operating in an isolated environment as well as in a multi-machine power system, performing very well when applied to different types of equipment and various kinds of internal faults.
14
Stefopoulos, Georgios Konstantinos. "Quadratic power system modeling and simulation with application to voltage recovery and optimal allocation of VAr support." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29695.
Full textAbstract:
Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010.Committee Chair: Meliopoulos, A. P. Sakis; Committee Member: Deng, Shijie; Committee Member: Divan, Deepakraj; Committee Member: Harley, Ronald; Committee Member: Taylor, David. Part of the SMARTech Electronic Thesis and Dissertation Collection.
15
Latzo, Curtis Thomas. "Approaches to Arc Flash Hazard Mitigation in 600 Volt Power Systems." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3198.
Full textAbstract:
ABSTRACT
Federal regulations have recognized that arc flash hazards are a critical source of potential injury. As a consequence, in order to work on some electrical equipment, the energy source must be completely shut-down. However, power distribution systems in mission critical facilities such as hospitals and data centers must sometimes remain energized while being maintained. In recent years the Arc Flash Hazard Analysis has emerged as a power system tool that informs the qualified technician of the incident energy at the equipment to be maintained and recommends the proper protective equipment to wear. Due to codes, standards and historically acceptable design methods, the Arc Flash Hazard is often higher and more dangerous than necessary.
This dissertation presents detailed methodology and proposes alternative strategies to be implemented at the design stage of 600 volt facility power distribution systems which will decrease the Arc Flash Hazard Exposure when compared to widely used code acceptable design strategies. Software models have been developed for different locations throughout a power system. These software model simulations will analyze the Arc Flash Hazard in a system designed with typical mainstream code acceptable methods. The model will be changed to show implementation of arc flash mitigation techniques at the system design level. The computer simulations after the mitigation techniques will show significant lowering of the Arc Flash Hazard Exposure.
16
Wang, Zhenyuan. "Artificial Intelligence Applications in the Diagnosis of Power Transformer Incipient Faults." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/28594.
Full textAbstract:
This dissertation is a systematic study of artificial intelligence (AI) applications for the diagnosis of power transformer incipient fault.
The AI techniques include artificial neural networks (ANN, or briefly neural networks - NN), expert systems, fuzzy systems and multivariate regression.
The fault diagnosis is based on dissolved gas-in-oil analysis (DGA). A literature review showed that the conventional fault diagnosis methods, i.e. the ratio methods (Rogers, Dornenburg and IEC) and the key gas method, have limitations such as the "no decision" problem. Various AI techniques may help solve the problems and present a better solution.
Based on the IEC 599 standard and industrial experiences, a knowledge-based inference engine for fault detection was developed. Using historical transformer failure data from an industrial partner, a multi-layer perceptron (MLP) modular neural network was identified as the best choice among several neural network architectures. Subsequently, the concept of a hybrid diagnosis was proposed and implemented, resulting in a combined neural network and expert system tool (the ANNEPS system) for power transformer incipient diagnosis. The abnormal condition screening process, as well as the principle and algorithms of combining the outputs of knowledge based and neural network based diagnosis, were proposed and implemented in the ANNEPS. Methods of fuzzy logic based transformer oil/paper insulation condition assessment, and estimation of oil sampling interval and maintenance recommendations, were also proposed and implemented.
Several methods of power transformer incipient fault location were investigated, and a 7Ã 21Ã 5 MLP network was identified as the best choice. Several methods for on-load tap changer (OLTC) coking diagnosis were also investigated, and a MLP based modular network was identified as the best choice. Logistic regression analysis was identified as a good auditor in neural network input pattern selection processes.
The above results can help developing better power transformer maintenance strategies, and serve as the basis of on-line DGA transformer monitors.Ph. D.
17
Luo, Dong 1966. "Detection and diagnosis of faults and energy monitoring of HVAC systems with least-intrusive power analysis." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8746.
Full textAbstract:
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Architecture, 2001.Includes bibliographical references (p. 171-175).
Faults indicate degradation or sudden failure of equipment in a system. Widely existing in heating, ventilating, and air conditioning (HVAC) systems, faults always lead to inefficient energy consumption, undesirable indoor air conditions, and even damage to the mechanical components. Continuous monitoring of the system and analysis of faults and their major effects are therefore crucial to identifying the faults at the early stage and making decisions for repair. This requires the method of fault detection and diagnosis (FDD) not only to be sensitive and reliable but also to cause minimal interruption to the system's operation at low cost. However, based on additional sensors for the specific information of each component or black-box modeling, current work of fault detection and diagnosis introduces too much interruption to the system's normal operation associated with sensor installation at unacceptable cost or requires a long time of parameter training. To solve these problems, this thesis first defines and makes major innovations to a change detection algorithm, the generalized likelihood ratio (GLR), to extract useful information from the system's total power data. Then in order to improve the quality of detection and simplify the training of the power models, appropriate multi-rate sampling and filtering techniques are designed for the change detector. From the detected variations in the total power, the performance at the system's level is examined and general problems associated with unstable control and on/off cycling can be identified. With the information that are basic to common HVAC systems, power functions are established for the major components, which help to obtain more reliable detection and more accurate estimation of the systems' energy consumption. In addition, a method for the development of expert rules based on semantic analysis is set up for fault diagnosis . Power models at both system and component levels developed in this thesis have been successfully applied to tests in real buildings and provide a systematic way for FDD in HVAC systems at low cost and with minimal interruption to systems' operation.
by Dong Luo.
Ph.D.
18
Zamboni, Lucca. "Detecção e localização de faltas em sistemas elétricos de distribuição usando abordagem inteligente baseada em análise espectral de sinais." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-27112013-110022/.
Full textAbstract:
O objetivo deste trabalho é estudar a identificação, classificação, localização e setorização de faltas em redes de distribuição radiais, verificar a maneira de aplicar e integrar diversas ferramentas numéricas convencionais, assim como ferramentas de sistemas inteligentes, visando identificar a ocorrência de uma falta, classificar as fases envolvidas com a mesma, e aplicar as diversas ferramentas existentes a fim de localizar em tempo real o eventual local onde houve a ocorrência da falta, permitindo que a mesma possa ser setorizada dentro do sistema da concessionária e informada ao centro de operações, usando uma nova abordagem inteligente baseada em análise espectral de sinais.The aim of this work is study the identification, classification, location and sectorization of a fault in distribution radial networks, check how to implement and integrate various conventional numerical tools, as well as intelligent systems based tools, to identify the occurrence of a fault, classify the phases involved with it, and apply the various tools available to locate the place where a fault was occurred in real time, enabling it to be sectorized into the utility system and informed to operational center using a new intelligent approach based on spectral signals analysis.
19
Salomonsson, Daniel. "Modeling, Control and Protection of Low-Voltage DC Microgrids." Doctoral thesis, Stockholm : Elektriska energisystem, Electric Power Systems, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4666.
Full text
20
SANTOS, GEAN R. dos. "Algoritmo de colônia de formigas e redes neurais artificiais aplicados na monitoração e detecção de falhas em centrais nucleares." reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26798.
Full textAbstract:
Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-11-11T09:45:23Z
No. of bitstreams: 0Made available in DSpace on 2016-11-11T09:45:23Z (GMT). No. of bitstreams: 0
Um desafio recorrente em processos produtivos é o desenvolvimento de sistemas de monitoração e diagnóstico. Esses sistemas ajudam na detecção de mudanças inesperadas e interrupções, prevenindo perdas e mitigando riscos. Redes Neurais Artificiais (RNA) têm sido largamente utilizadas na criação de sistemas de monitoração. Normalmente as RNA utilizadas para resolver este tipo de problema são criadas levando-se em conta apenas parâmetros como o número de entradas, saídas e quantidade de neurônios nas camadas escondidas. Assim, as redes resultantes geralmente possuem uma configuração onde há uma total conexão entre os neurônios de uma camada e os da camada seguinte, sem que haja melhorias em sua topologia. Este trabalho utiliza o algoritmo de Otimização por Colônia de Formigas (OCF) para criar redes neurais otimizadas. O algoritmo de busca OCF utiliza a técnica de retropropagação de erros para otimizar a topologia da rede neural sugerindo as melhores conexões entre os neurônios. A RNA resultante foi aplicada para monitorar variáveis do reator de pesquisas IEA-R1 do IPEN. Os resultados obtidos mostram que o algoritmo desenvolvido é capaz de melhorar o desempenho do modelo que estima o valor de variáveis do reator. Em testes com diferentes números de neurônios na camada escondida, utilizando como comparativos o erro quadrático médio, o erro absoluto médio e o coeficiente de correlação, o desempenho da RNA otimizada foi igual ou superior ao da tradicional.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
21
Aleksandar, Stanisavljević. "Nova metoda detekcije propada napona u mreži sa distribuiranim generatorima." Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2019. https://www.cris.uns.ac.rs/record.jsf?recordId=110015&source=NDLTD&language=en.
Full textAbstract:
U ovoj doktorskoj disertaciji je predstavljena je nova metoda zadetekciju propada napona, zasnovana na Rekurentnojneuronskoj mreži i analizi u harmonijskom domenu. Metoda jenamenjena za primenu u savremenim distributivnim mrežamakoje sadrže obnovljive izvore, i u skladu sa tim je optimizovana itestirana. Pametna metoda postiže izuzetne rezultate u brzinidetekcije, sa prosečnim vremenom detekcije manjim od 1 ms, uzizuzetnu pouzdanost (preko 97%). U doktorskoj disertacijidokazana je i druga hipoteza, a to je da je moguće predvidetidubinu propada algoritmom zasnovanim na harmonijskoj analizi.In this PhD thesis, a novel method for the detection of voltage dips(sags), based on the Recurrent Neural Network and analysis in thefrequency domain, is presented. The method is intended for use inthe modern distribution grids that contains renewable sources, andaccordingly it is optimized and tested. The smart method achievesexceptional results in detection speed, with an average detectiontime of less than 1 ms and with high reliability (over 97%). In thePhD thesis, another hypothesis is proved, which claims that ispossible to predict the depth of dip with algorithm based on theharmonic analysis.
22
Liu, Xinyi. "Contribution to adaptative sliding mode, fault tolerant control and control allocation of wind turbine system." Thesis, Belfort-Montbéliard, 2016. http://www.theses.fr/2016BELF0295/document.
Full textAbstract:
Les principaux défis pour le déploiement de systèmes de conversion de l'énergie éolienne est de maximiser la puissance électrique produite, malgré les variations des conditions météorologiques, tout en minimisant les coûts de fabrication et de maintenance du système. L'efficacité de la turbine éolienne est fortement dépendante des perturbations de l'environnement et des paramètres variables du système, tels que la vitesse du vent et l'angle de tangage. Les incertitudes sur le système sont difficiles à modéliser avec précision alors qu'ils affectent sa stabilité.Afin d'assurer un état de fonctionnement optimal, malgré les perturbations, le commande adaptative peut jouer un rôle déterminant. D'autre part, la synthèse de commandes tolérantes aux défauts, capables de maintenir les éoliennes connectées au réseau après la survenance de certains défauts est indispensable pour le bon fonctionnement du réseau. Le travail de cette thèse porte sur la mise en place de lois de commande adaptatives et tolérantes aux défauts appliqués aux systèmes de conversion de l'énergie éolienne. Après un état de l'art, les contributions de la thèse sont :Dans la première partie de la thèse, un modèle incertain non linéaire du système de conversion d'énergie éolienne avec un générateur à induction à double alimentation est proposé. Une nouvelles approches de commande adaptative par mode glissant est synthétisée et ensuite appliquée pour optimiser l'énergie issue de l'éolienne.Dans la deuxième partie, une nouvelle commande par modes glissants tolérante aux défauts et basée sur les modes glissants intégrales est présentée. Puis, cette méthode est appliquée afin de forcer la vitesse de la turbine éolienne à sa valeur optimale en prenant en compte des défauts qui surviennent sur l'actionneurThe main challenges for the deployment of wind energy conversion systems (WECS) are to maximize the amount of good quality electrical power extracted from wind energy over a significantly wide range of weather conditions and minimize both manufacturing and maintenance costs. Wind turbine's efficiency is highly dependent on environmental disturbances and varying parameters for operating conditions, such as wind speed, pitch angle, tip-speed ratio, sensitive resistor and inductance. Uncertainties on the system are hard to model exactly while it affects the stability of the system. In order to ensure an optimal operating condition, with unknown perturbations, adaptive control can play an important role. On the other hand, a Fault Tolerant Control (FTC) with control allocation that is able to maintain the WECS connected after the occurrence of certain faults can avoid major economic losses. The thesis work concerns the establishment of an adaptive control and fault diagnosis and tolerant control of WECS. After a literature review, the contributions of the thesis are:In the first part of the thesis, a nonlinear uncertain model of the wind energy conversion system with a doubly fed induction generator (DFIG) is proposed. A novel Lyapunov-based adaptive Sliding Mode (HOSM) controller is designed to optimize the generated power.In the second part, a new output integral sliding mode methodology for fault tolerant control with control allocation of linear time varying systems is presented. Then, this methodology has been applied in order to force the wind turbine speed to its optimal value the presence of faults in the actuator
23
Öhrström, Magnus. "Fast fault detection for power distribution systems." Licentiate thesis, KTH, Electrical Systems, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1565.
Full textAbstract:
The main topic of this licentiate thesis is fast faultdetection. The thesis summaries the work performed in theprojectFast fault detection for distributionsystems.
In the first chapters of the thesis the termfastis used in a general manner. The term is laterdefined based upon considerations and conclusions made in thefirst chapters and then related to a specific time.
To be able to understand and appreciate why fast faultdetection is necessary, power system faults and theirconsequences are briefly discussed. The consequences of a faultare dependent of a number of different factors, one of thefactors being the duration of the fault.
The importance of the speed of the fault detection dependson the type of equipment used to clear the fault. A circuitbreaker which interrupt currents only when they pass through anatural zero crossing might be less dependent on the speed ofthe fault detection than a fault current limiter which limitsthe fault current before it has reached its first prospectivecurrent peak.
In order to be able to detect a fault in a power system, thepower system must be observed, i.e., measurements of relevantquantities must be performed so that the fault detectionequipment can obtain information of the state of the system.The fault detection equipment and some general methods of faultdetection are briefly described.
Some algorithms and their possible adaptation to fast faultdetection are described. A common principle of many algorithmsare that they assume that either a signal or the power systemobject can be described by a model. Sampled data values arethen fitted to the model so that an estimate of relevantparameters needed for fault detection is obtained. An algorithmwhich do not fit samples to a model but use instantaneouscurrent values for fault detection is also described andevaluated.
Since the exact state of a power system never is known dueto variations in power production and load, a model of thepower system or of the signal can never be perfect, i.e., theestimated parameter can never be truly correct. Furthermore,errors from the data acquisition system contribute to the totalerror of the estimated parameter.
Two case studies are used to study the performance of the(modified) algorithms. For those studies it has been shown thatthe algorithms can detect a fault within approximately 1msafter fault inception and that one of the algorithms candiscriminate between a fault and two types of common powersystem transients (capacitor and transformer energization).
The second case study introduced a system with two sourceswhich required a directional algorithm to discriminate betweenfaults inside or outside the protection zone.
It is concluded that under certain assumptions it ispossible to detect power system faults within approximately 1msand that it is possible to discriminate a power system faultfrom power system transient that regularly occurs within powersystems but which not are faults.
24
Booth, Stephen H. "Expert systems for fault analysis." Thesis, Aston University, 1993. http://publications.aston.ac.uk/9802/.
Full textAbstract:
The initial aim of this research was to investigate the application of expert Systems, or Knowledge Base Systems technology to the automated synthesis of Hazard and Operability Studies. Due to the generic nature of Fault Analysis problems and the way in which Knowledge Base Systems work, this goal has evolved into a consideration of automated support for Fault Analysis in general, covering HAZOP, Fault Tree Analysis, FMEA and Fault Diagnosis in the Process Industries. This thesis described a proposed architecture for such an Expert System. The purpose of the System is to produce a descriptive model of faults and fault propagation from a description of the physical structure of the plant. From these descriptive models, the desired Fault Analysis may be produced. The way in which this is done reflects the complexity of the problem which, in principle, encompasses the whole of the discipline of Process Engineering. An attempt is made to incorporate the perceived method that an expert uses to solve the problem; keywords, heuristics and guidelines from techniques such as HAZOP and Fault Tree Synthesis are used. In a truly Expert System, the performance of the system is strongly dependent on the high quality of the knowledge that is incorporated. This expert knowledge takes the form of heuristics or rules of thumb which are used in problem solving. This research has shown that, for the application of fault analysis heuristics, it is necessary to have a representation of the details of fault propagation within a process. This helps to ensure the robustness of the system - a gradual rather than abrupt degradation at the boundaries of the domain knowledge.
25
Jia, Ke. "Impedance based fault location in power distribution systems." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/28518/.
Full textAbstract:
This thesis presents an investigation into impedance based fault location methods which directly use the fault transient as an excitation source to provide fast and accurate fault locations in small distribution systems such as the modem marine and aircraft power systems which have Integrated Power System (IPS) configuration. Fast and accurate fault location on un-exposed power distribution lines is of vital importance to expedite service restoration and improving the reliability of the power system. Two fault location algorithms are developed: the single-ended method and the double-ended method. The singled-ended algorithm which captures current and voltage waveforms from one end of the distribution cable estimates the fault locations using an iteration calculation. The double-ended method has a simple algorithm and is robust to different fault situations but requires additional data measured from the remote end of the cable. Both simulation and experimental tests have been done and the results are good enough to validate that the developed methods can locate fault positions using a 12ms window and otter an accuracy of within 1m in the proposed distribution system. The advantages and disadvantages of the proposed fault location methods are investigated under different fault situations. The possibility of employing the two methods in protection of faults in a marine power system is demonstrated. Due to the special characteristics of the marine power system, an active method which simply involves adding an IGBT switch is proposed for the earth fault protection.
26
Segundo, Sevilla Felix Rafael. "Fault-tolerant wide-area control of power systems." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/12231.
Full textAbstract:
In this thesis, the stability and performance of closed-loop systems following the loss of sensors or feedback signals (sensor faults) are studied. The objective is to guarantee stability in the face of sensor faults while optimising performance under nominal (no sensor fault) condition. One of the main contributions of this work is to deal effectively with the combinatorial binary nature of the problem when the number of sensors is large. Several fault-tolerant controller and observer architectures that are suitable for different applications are proposed and their effectiveness demonstrated. The problems are formulated in terms of the existence of feasible solutions to linear matrix inequalities. The formulations presented in this work are described in a general form and can be applied to a large class of systems. In particular, the use of fault-tolerant architectures for damping inter-area oscillations in power systems using wide-area signals has been demonstrated. As an extension of the proposed formulations, regional pole placement to enhance the damping of inter-area modes has been incorporated. The objective is to achieve specified damping ratios for the inter-area modes and maximise the closed-loop performance under nominal condition while guaranteeing stability for all possible combinations of sensors faults. The performances of the proposed fault-tolerant architectures are validated through extensive nonlinear simulations using a simplified equivalent model of the Nordic power system.
27
Coppens, J. M. "Logical fault analysis of fault secure systems using VHDL." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq22759.pdf.
Full text
28
Mabeta, Simon Jorums. "Open Conductor Faults and Dynamic Analysis of a Power System." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18994.
Full textAbstract:
The overall goal of this thesis is to study and understand Open Conductor Faults and to assess their impact on the stability of a power system. In particular, the thesis has investigated the effect of this type of the fault on the dynamic electromechanical behavior of synchronous machine. The thesis has also focused on the effect of generator and transformer grounding as well as the effect of transformer winding configuration on the stability of the power system during this type of fault.Open conductor faults are series faults which involve a break in one or two of the three conductors of a three phase power system. As such, the fault is an unsymmetrical fault and thus, the theory of symmetrical components was revisited. Symmetrical components and symmetrical circuits have been used to analyze both types of open conductor faults in order to understand the phenomenon and ease calculations. A dual approach to this study has been undertaken. The phenomenon is treated analytically through calculations and then the calculated results are confirmed through computer simulations using SIMPOW, a power system simulation software. In either approach, it is evidently clear, through the use of Eigen values and calculated damping coefficients, that the damping of the machine in an open conductor situation is worse than the for the normal case without the fault. A research in to the developed equations for damping has been undertaken. The theory of induction motors is applied in development of both the positive and negative damping power. The equation for negative damping power is developed first, using the symmetrical component concept and secondly, using the single phasing concept. In the investigation of transformer winding configurations and the grounding generators and transformers, different scenarios have been considered and simulated in order to show their effect during the fault. Finally the two open conductor case has also been investigated analytically and through computer simulation. The effect of grounding is shown in the results obtained. It shows that power transfer only occurs when there is a return path from the point of the fault to the generator.
29
Fan, Wen. "ADVANCED FAULT AREA IDENTIFICATION AND FAULT LOCATION FOR TRANSMISSION AND DISTRIBUTION SYSTEMS." UKnowledge, 2019. https://uknowledge.uky.edu/ece_etds/144.
Full textAbstract:
Fault location reveals the exact information needed for utility crews to timely and promptly perform maintenance and system restoration. Therefore, accurate fault location is a key function in reducing outage time and enhancing power system reliability.
Modern power systems are witnessing a trend of integrating more distributed generations (DG) into the grid. DG power outputs may be intermittent and can no longer be treated as constants in fault location method development. DG modeling is also difficult for fault location purpose. Moreover, most existing fault location methods are not applicable to simultaneous faults. To solve the challenges, this dissertation proposes three impedance-based fault location algorithms to pinpoint simultaneous faults for power transmission systems and distribution systems with high penetration of DGs.
The proposed fault location algorithms utilize the voltage and/or current phasors that are captured by phasor measurement units. Bus impedance matrix technique is harnessed to establish the relationship between the measurements and unknown simultaneous fault locations. The distinct features of the proposed algorithms are that no fault types and fault resistances are needed to determine the fault locations. In particular, Type I and Type III algorithms do not need the information of source impedances and prefault measurements to locate the faults. Moreover, the effects of shunt capacitance are fully considered to improve fault location accuracy. The proposed algorithms for distribution systems are validated by evaluation studies using Matlab and Simulink SimPowerSystems on a 21 bus distribution system and the modified IEEE 34 node test system. Type II fault location algorithm for transmission systems is applicable to untransposed lines and is validated by simulation studies using EMTP on a 27 bus transmission system.
Fault area identification method is proposed to reduce the number of line segments to be examined for fault location. In addition, an optimal fault location method that can identify possible bad measurement is proposed for enhanced fault location estimate. Evaluation studies show that the optimal fault location method is accurate and effective.
The proposed algorithms can be integrated into the existing energy management system for enhanced fault management capability for power systems.
30
Zhou, Keming. "Computation of asymmetric fault current in complex power systems." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287924.
Full text
31
Sihite, Josep Franklin. "Failure Analysis of Power Transformer Based on Fault Tree Analysis." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/180498.
Full text
32
Xiu, Wanjing. "FAULT LOCATION ALGORITHMS, OBSERVABILITY AND OPTIMALITY FOR POWER DISTRIBUTION SYSTEMS." UKnowledge, 2014. http://uknowledge.uky.edu/ece_etds/48.
Full textAbstract:
Power outages usually lead to customer complaints and revenue losses. Consequently, fast and accurate fault location on electric lines is needed so that repair work can be carried out as fast as possible.
Chapter 2 describes novel fault location algorithms for radial and non-radial ungrounded power distribution systems. For both types of systems, fault location approaches using line to neutral or line to line measurements are presented. It’s assumed that network structure and parameters are known, so that during-fault bus impedance matrix of the system can be derived. Functions of bus impedance matrix and available measurements at substation are formulated, from which the unknown fault location can be estimated. Evaluation studies on fault location accuracy and robustness of fault location methods to load variations and measurement errors has been performed.
Most existing fault location methods rely on measurements obtained from meters installed in power systems. To get the most from a limited number of meters available, optimal meter placement methods are needed. Chapter 3 presents a novel optimal meter placement algorithm to keep the system observable in terms of fault location determination. The observability of a fault location in power systems is defined first. Then, fault location observability analysis of the whole system is performed to determine the least number of meters needed and their best locations to achieve fault location observability. Case studies on fault location observability with limited meters are presented. Optimal meter deployment results based on the studied system with equal and varying monitoring cost for meters are displayed.
To enhance fault location accuracy, an optimal fault location estimator for power distribution systems with distributed generation (DG) is described in Chapter 4. Voltages and currents at locations with power generation are adopted to give the best estimation of variables including measurements, fault location and fault resistances. Chi-square test is employed to detect and identify bad measurement. Evaluation studies are carried out to validate the effectiveness of optimal fault location estimator. A set of measurements with one bad measurement is utilized to test if a bad data can be identified successfully by the presented method.
33
Chen, Jie. "Fault Section Identification for Power Distribution Systems Using Online Measurements." UKnowledge, 2015. http://uknowledge.uky.edu/ece_etds/70.
Full textAbstract:
Fault location is very important for distribution systems, and quickly identifying the fault and restoring the system can help reduce the outage time and make the system more reliable. In this thesis, a method for locating faults on distribution systems is introduced to quickly identify the faulted feeder sections by using the overcurrent information from the switches in the system. Fuzzy logic is utilized. The proposed method can quickly and accurately locate faulted sections with different fault locations, fault types and fault resistances. The method is applicable to cases with single-faults or multi-faults, and is applicable to networks with multi-sources. The case study has demonstrated the effectiveness of the proposed method.
34
Wang, Chun. "Methodologies and algorithms for fault locators in modern power systems." Thesis, University of the West of England, Bristol, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392859.
Full textAbstract:
Following world wide deregulation of the electrical power industry, the requirements for high quality and highly reliable power supplies are increasing. Comprehensive and systematic computer based methodologies and algorithms for fault locators in power systems are needed to support reliable, independent and comprehensive fault diagnosis or accurate fault location, fast fault detection and correct fault classification. This thesis describes work to develop novel fault diagnosis techniques and accurate fault location algorithms for fault locators using system-wide information of modern power systems. Fast and efficient modern communication techniques make it possible to apply the novel fault locator system in practice. The fault diagnosis techniques use fault messages obtained from current and voltage sensors installed in radial and meshed networks respectively. A faulty section in the meshed network can be detected by analysing the network's topologic structure and the measurements of the fundamental frequency voltages obtained from voltage sensors; while for the radial network, current sensors are used to trace the path of a fault. The fault diagnosis techniques can work independently from protection devices, and circuit breakers, and can be implemented economically in the low- and medium-voltage power systems, because current and voltage sensors can be made cheaply. In order to achieve very accurate fault location for the EHV transmission systems with long transmission lines and complex network topology, algorithms based on the wavelet transform, travelling wave concept and GPS synchronisation have been developed. When a fault occurs, fault generated transient waves propagate from fault point to line terminals and then to the other nodes in the whole network. Fault transient detectors are installed at nodes in the meshed network, at substations and customer terminals in the radial system to capture the time of fault transient signal arrival. From the time recorded and topologic network structure, very accurate fault location can be achieved. The thesis also describes and compares applications of digital Fourier transform, least squares method and Kalman filters for fast measurements in current and voltage sensors, for fault classification and fault detection, and the wavelet transform used in fault transient detectors. Methodologies and algorithms developed have been validated by ATP/EMTP simulation on different networks, such as, traditional twosource system and IEEE 14-bus system. The maIn advantage of the developed methodologies and algorithms for fault locators in power systems is the use of system-wide fault messages in the electrical networks. The fault locators will efficiently support the operators in the control centres and relevant substations with clear fault information allowing them to take suitable actions for fault emergency and restoration of power supplies. This will be beneficial in reducing the outage time required for inspection, damage repair and restoration of the power supply. Reliability, security and power quality will be improved for the customers.
35
Ramadan, Asmaiel. "Permanent magnet fault current limiters for electrical power protection systems." Thesis, Sheffield Hallam University, 2018. http://shura.shu.ac.uk/22433/.
Full textAbstract:
The main aim of this work is to design and test a permanent magnet fault current limiter (PMFCL) to limit the fault current in electrical power system network. The (fit and forget) device presented in this thesis is based on two important aspects; the best selection of the state of the art soft and hard magnetic materials and the design topology of PMFCL. Rare earth material is used as a permanent magnet, which is the main source of excitation to keep the non-oriented silicon steel iron core in magnetic saturation state. During the normal operation of the device the saturated core offers low impedance to the grid and during the fault state the core inherently rushed to high impedance state that limits the high short circuit current. A commercial Finite Element software (FEM) was used in the device modelling techniques from the commencement till the end of the final design. The work commenced with the verifications and investigations of a recently reported model in 2D (FEM). Then, a prototype of small scale, in two design configurations of the same PMFCL specifications, was built and tested at the electrical laboratory of Sheffield Hallam University to verify the simulation results and to access the design of the PMFCL device. After that, the 11-kV PMFCL for substation distribution transformer was designed. Finally, the low voltage toroidal core PMFCL was proposed for the existing renewable energy and future wind-photovoltaic (wind-PV) step-up transformer. The dry type PMFCL current-inductance profiles were obtained by 3D (FEM) magneto static solver to predict the behaviour of the devices in the abnormal condition. The calculated RMS current, using 3D (FEM) time saving inductance-current approach, agreed with the peak transient currents obtained by the lengthy computation process time-step solver. The current limitation capability has been calculated in comparison with the air-cored of similar specifications as the PMFCL device and a useful reduction in the fault current has been achieved. The simulation results proved that the proposed PMFCL topologies (toroidal and square-shaped) can protect the renewable energy generator-transformer and real power grids from the fault current. Both the toroidal and full scale PMFCL devices initial and energy cost over an expected service of life have been evaluated. The merit of the PMFCL device is that it reduces downtime during power system’s outages by mitigating the severe fault current in the first half cycle.
36
Nixon, Casey William. "Analysis of fault networks and conjugate systems." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/359064/.
Full textAbstract:
Faults networks exist over a range of scales and are important for understanding the brittle deformation and fluid transport processes within the Earth’s crust. Analysing fault networks by characterizing the organization of faulting within them; the distribution of numerous attributes (i.e. displacement, density, strain etc.); and assessing their connectivity is essential, as these provide information about a fault networks behaviour, growth and development. This thesis presents an analysis of various strike-slip and normal fault networks from north Devon, New Zealand and Alaska. The fault networks are interpreted using an array of datasets such as field observation, aerial photography, multibeam bathymetry, high resolution seismic profiles and 3-D seismic volumes. These are integrated with ArcGIS and robust methodologies are used to analyse each network. Spatial mapping of various attributes indicates that there is much heterogeneity in the organization of faulting within fault networks. Different domains, defined by their deformation style and/or their kinematic behaviour, can develop within a fault network. Domino domains have a dominant fault set with larger displacements, which controls systematic rotation of faults and bedding. Conjugate domains form when there are equal sizes and proportions of each fault set and show little or no rotation of bedding. Domains interact with one another and can form large damage zones to accommodate changes in strain. Strain accommodated by each domain can vary within a network and is either distributed across numerous faults or localized to a few large faults, however, the network will preserve strain compatibility between domains. Fault interactions including splays, abutments and cross-cutting relationships are characterized by different displacement profiles. These can be divided into two groups based on their kinematics: antithetic interactions and synthetic interactions, which involve faults with the opposite and same motion senses, respectively. Fault development can be influenced by interactions with pre-existing structures. When earlier fault generations are reactivated they affect the orientation, displacement and distribution of new fault generations. A topological analysis is developed to characterize fault networks and assess connectivity. This considers a network to comprise of nodes (I, Y and X) and branches (I-I, I-C and C-C) between nodes. The number and proportion of each topological component can be used to produce parameters that relate to the connectivity of a network, such as the number of connections per line or per branch. They can also provide information about the clustering and compartmentalization within a network.
37
Daniel, J. S. "Independent mode protection of three ended power systems." Thesis, University of Bath, 1991. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280896.
Full text
38
Jalel, Nameer Adnan. "Fault diagnosis and accident analysis in nuclear power plant." Thesis, University of Sheffield, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335950.
Full text
39
Othman, Mohd Fauzi. "A hybrid systems approach to control and fault detection and accommodation in power systems." Thesis, University of Sheffield, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412141.
Full text
40
Ferreira, Kurt Josef. "Fault location for power transmission systems using magnetic field sensing coils." Link to electronic thesis, 2007. http://www.wpi.edu/Pubs/ETD/Available/etd-050707-120755/.
Full text
41
Widener, Christopher. "Fault isolation in power electronic based distribution systems without circuit breakers." Thesis, The Florida State University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1559659.
Full textAbstract:
In the Future Renewable Electric Energy Distribution and Management (FREEDM) system, solid state Fault Isolation Devices (FIDs) are used to react to signals from a fault detection and location system to isolate faulted sections of a fault current limited power electronics based 12.47 kV distribution system. They accomplish this by interrupting fault currents, which in the FREEDM system are limited by Solid State Transformers (SST). However, as was expected, due to its silicon transistor technology, the developed FID prototype demonstrated rather high on-state losses during its operation. Therefore, it is necessary to perform comparison studies with alternative methods of sectionalizing faulted parts of the FREEDM grid. To respond to this need, a system study has been undertaken to explore an alternative fault isolation strategy, which instead of allowing fault currents to remain in the system uses the abilities of the SSTs to completely turn off fault currents. Once this turn-off has been accomplished, regular mechanical disconnects isolate the faulted section and the system is reenergized. Behavioral 3-phase PSCAD average-value SST models have been developed and are used in a representative model of the FREEDM Green Hub to demonstrate how this strategy would operate. Simulation data is presented that shows how the SSTs would react to fault situations, remove fault currents, and reenergize the system. The characteristic example system was constructed and parameterized allowing for sensitivity analyses to be performed. A comparison is made with the fault-current-breaking FID method of fault isolation currently in use and it is discussed how the presented approach can be used to evaluate future FREEDM fault isolation strategies.
42
Myers, Thomas Oliver. "Test analysis & fault simulation of microfluidic systems." Thesis, University of Hull, 2010. http://hydra.hull.ac.uk/resources/hull:3509.
Full textAbstract:
This work presents a design, simulation and test methodology for microfluidic systems, with particular focus on simulation for test. A Microfluidic Fault Simulator (MFS) has been created based around COMSOL which allows a fault-free system model to undergo fault injection and provide test measurements. A post MFS test analysis procedure is also described.A range of fault-free system simulations have been cross-validated to experimental work to gauge the accuracy of the fundamental simulation approach prior to further investigation and development of the simulation and test procedure.A generic mechanism, termed a fault block, has been developed to provide fault injection and a method of describing a low abstraction behavioural fault model within the system. This technique has allowed the creation of a fault library containing a range of different microfluidic fault conditions. Each of the fault models has been cross-validated to experimental conditions or published results to determine their accuracy.Two test methods, namely, impedance spectroscopy and Levich electro-chemical sensors have been investigated as general methods of microfluidic test, each of which has been shown to be sensitive to a multitude of fault. Each method has successfully been implemented within the simulation environment and each cross-validated by first-hand experimentation or published work.A test analysis procedure based around the Neyman-Pearson criterion has been developed to allow a probabilistic metric for each test applied for a given fault condition, providing a quantitive assessment of each test. These metrics are used to analyse the sensitivity of each test method, useful when determining which tests to employ in the final system. Furthermore, these probabilistic metrics may be combined to provide a fault coverage metric for the complete system.The complete MFS method has been applied to two system cases studies; a hydrodynamic “Y” channel and a flow cytometry system for prognosing head and neck cancer.Decision trees are trained based on the test measurement data and fault conditions as a means of classifying the systems fault condition state. The classification rules created by the decision trees may be displayed graphically or as a set of rules which can be loaded into test instrumentation. During the course of this research a high voltage power supply instrument has been developed to aid electro-osmotic experimentation and an impedance spectrometer to provide embedded test.
43
Punnekkat, Sasikumar. "Schedulability analysis for fault tolerant real-time systems." Thesis, University of York, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362040.
Full text
44
Velaga, Srikirti. "Fault Modeling and Analysis for Multiple-Voltage Power Supplies in Low-Power Design." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1368026670.
Full text
45
Hong, Mingguo. "Controllability and diagnosis in electric power systems /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/6088.
Full text
46
Ram, Prakash Ranjithh Raj. "Study of an Isolated and a Non-Isolated Modular DC/DC Converter : In Multi-Terminal HVDC/MVDC grid systems." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278495.
Full textAbstract:
För sammankoppling av multi-terminala HVDC-system med punkt-till-punkt kopplingar ärDC-DC-omvandlaren den enda möjliga sammankopplingen. Därför genomgår problemenmed spänningsmatchning och likspänningsströmbegränsning i högspännings DC-systemomfattande forskning samt ligger i fokus för denna avhandling. Först analyseras toppmodernatopologier för högspännings DC-DC-omvandlare som används för samtrafik av flera terminalaHVDC-system. De analyserade topologierna jämförs sedan baserat på dess olika funktioner.Topologin för en konventionell icke-isolerad DC-DC-omvandlare analyseras när det gäller design,kostnad, storlek, förlust och effektstyrningskapacitet. Först skapas en matematisk modell ochsedan utförs en numerisk analys för olika arbetsområden. Därefter görs en jämförelse av entvåfas-icke-isolerad DC-omvandlare baserad på energilagring, maximal likströmsöverföring ochtotala förluster. Simulering utförs av en tvåfas och en trefas icke-isolerad DC-omvandlare iPSCAD med olika typer av styrenheter. Dessutom tas en isolerad omvandlartopologi och analyserasi detalj från matematisk modellering till validering med hjälp av simuleringsresultat.Olika typer av felanalyser för både isolerad och icke-isolerad omvandlartopologi görs. Slutligenutförs även analyser av DC-felet i olika möjliga anslutningar av omvandlaren i Multi-TerminalGrid, dvs Monopole, Bipole med både symmetriska och asymmetriska konfigurationer.For interconnection of multi-terminal HVDC systems involving point-to-point links, aDC-DC converter is the only possible way to interconnect. Therefore, the issues of voltagematching and DC fault current limiting in high voltage DC systems are undergoing extensiveresearch and are the focus of this thesis. Starting with analyzing the state of the art highvoltage DC-DC converter topologies for interconnection of multi-terminal HVDC systems andbenchmarking each converter topology based on different functionalities. A basic non-isolatedDC-DC converter topology is analyzed in terms of design, cost, sizing, losses and power controlcapability. First, starting with the mathematical modeling and then the numerical analysis isdone for different operating regions. Next, it is compared with the two-phase non-isolated DCconverter based on energy storage, maximum DC power transfer, and total losses. Simulation oftwo-phase and three-phase non-isolated DC converter is done in PSCAD incorporating differenttypes of controllers. Then, an isolated converter topology is taken and analyzed in detail startingfrom mathematical modeling to validation using simulation results. Different types of faultsanalysis for both isolated and non-isolated converter topology is done. Finally, analyzing the DCfault in different possible connection of the converter in the multi-terminal grid, i.e. monopole,bipole in both symmetric and asymmetric configurations.
47
Li, Yizhe. "A FAULT LOCATION ALGORITHM FOR UNBALANCED DISTRIBUTION SYSTEM WITHOUT FAULT TYPE INFORMATION." UKnowledge, 2018. https://uknowledge.uky.edu/ece_etds/112.
Full textAbstract:
Power system faults normally result in system damage, profit loss and consumer dissatisfaction. Consequently, there is a strong demand on precise and fast fault location estimation for power system to minimize the system restoration time.
This paper examines a method to locate short-circuit faults on a distribution system with unbalanced loads without fault type information. Bus impedance matrix technique was harnessed in the fault location estimation algorithm. The system data including line impedances, source impedance and distribution system layout was assumed to be known factors, hence pre-fault bus impedance can be calculated and implemented into the algorithm. Corresponding methods to derive system matrix information were discussed. Case studies were performed to evaluate the accuracy of the fault location algorithm and illustrate the robust performance under measurements errors influences, load variation impacts and load compensation implementations.
Traditional fault location methods involve current and voltage measurements mandatorily locating at each ends of faulted section to locate the fault. The method examined finds fault location for distribution system utilizing impedance matrix accompanied with sparse measurements in the power network. This method fully considers the unbalance of distribution system.
48
Arana, Andrew Jex. "Power Systems Analysis in the Power-Angle Domain." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/30001.
Full textAbstract:
The idea of performing power systems dynamic analysis in the power-angle domain has been hinted at by previous researchers, but this may be the first published document to develop detailed techniques by which entire power systems can be represented and solved in the power-angle domain. With the widespread deployment of phasor measurement units and frequency data recorders the industry is looking for more real-time analytical tools to turn real-time wide-area measurements into useful information. Applications based on power-angle domain analysis are simple enough that they may be used online.
Power-angle domain analysis is similar to DC load-flow techniques in that a flat voltage profile is used and it is assumed that real power and voltage angle are completely decoupled from reactive power and voltage magnitude. The linearized equations for the dynamics of generators and loads are included in the model, which allows the electromechanical response to be solved using conventional circuit analysis techniques. The effect of generation trips, load switching, and line switching can be quickly approximated with nodal analysis or mesh analysis in the power-angle domain.
The analysis techniques developed here are not intended to be as accurate as time-domain simulation, but they are simpler and fast enough to be put online, and they also provide a better analytical insight into the system. Power-angle domain analysis enables applications that are not readily available with conventional techniques, such as the estimation of electromechanical propagation delays based on system parameters, the formulation of electromechanical equivalents, modal analysis, stability analysis, and event location and identification based on a small number of angle or frequency measurements. Fault studies and contingency analysis are typically performed with detailed time-domain simulations, where the electromechanical
response of the system is a function of every machine in the interconnection and the lines connecting them. All of this information is rarely known for the entire system for each operating condition; as a result, for many applications it may be more suitable to compute an approximation of the system response based on the current operating state of only the major lines and generators. Power-angle domain analysis is adept at performing such approximations.Ph. D.
49
Gammon, Tammy Lea. "Improved arcing-fault current models for low-voltage power systems (<1kV)." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/15675.
Full text
50
Lo, Wai Kau. "On the relative power of shared objects in fault-tolerant distributed systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0009/NQ27998.pdf.
Full text