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1
Rajkumar, Naganathy. "Novel algorithms for modern power systems". Thesis, City University London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390941.
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Kryukova, N. V., Evgen Viktorovych Goncharov i I. V. Polyakov. "Modern monitoring systems of electric power lines". Thesis, NTU "KhPI", 2018. http://repository.kpi.kharkov.ua/handle/KhPI-Press/38909.
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Kamarudin, Syalwani. "Advanced Doherty power amplifier design for modern communication systems". Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/115269/.
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Mobile communication technologies are becoming increasingly sophisticated and have experienced rapid evolution over the last few decades, and this is especially true for the base station transmitter. In response to the ever increasing demand in communication traffic and data throughput, largely driven by video based social media platforms, both spectral and power efficient device and systems are needed to fulfil the requirements. In terms of energy consumption, the power amplifier is an important component, and although developing efficient technologies for handset equipment is important, it is the base station element of the communications system that poses the greater challenge, having to deal with many channels simultaneously, resulting in the need to linearly and efficiently amplify highly dynamic phase and amplitude modulated signals possessing very large peak-to-average power ratios, at high power levels. This unique set of challenges has led to continuous research to improve the efficiency of amplifiers that can accommodate such signals, and the Doherty architecture has now become the architecture-of-choice. However, most of the previous research studies demonstrate Doherty performance enhancement through a ‘conventional’ design approach that uses one input source and a passive power splitter to deliver power to each half of the Doherty structure. They do not emphasize the additional efficiency and other performance improvements that are possible in Doherty amplifiers when using two different, independent and phase coherent input sources, attached to the input path of both main and auxiliary amplifiers. IV The novel research work presented in this thesis introduces an optimised design approach for Doherty amplifier architectures with individual input sources, as well as detailing a measurement architecture that is necessary to characterise such structures, using separate, phase-coherent input sources in a realistic measurement scenario. Finally, following extensive characterisation of a number of promising architectures, investigations around efficiency enhancement are focused around the adaption of gate bias applied to the auxiliary amplifier device, and identifying, for the first time, what is possible by generating different shaping functions that relate bias voltage to the magnitude of the input signal. One completely new area of research and novelty introduced in this work for example shows how choosing the right shaping function can give improved linearity and importantly linearisability by producing a flat gain over dynamic range. Note that linearisability is important, and is defined here as the term used to describe the ease with which the non-linearities of a device or power amplifier can be corrected. It is often assumed in power amplifier design that efficiency and power are the most important parameters, and that modern digital pre-distortion (DPD) techniques can easily correct any non-linearity that may result. Industry is now finding that this is not the case however, and the type and nature of the non-linearity in terms to AM-AM and AM-PM distortion is very important in determining of the degree of linearization possible.
4
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.
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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.
5
Shao, Jin. "Advanced Power Amplifiers Design for Modern Wireless Communication". Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc804973/.
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Modern wireless communication systems use spectrally efficient modulation schemes to reach high data rate transmission. These schemes are generally involved with signals with high peak-to-average power ratio (PAPR). Moreover, the development of next generation wireless communication systems requires the power amplifiers to operate over a wide frequency band or multiple frequency bands to support different applications. These wide-band and multi-band solutions will lead to reductions in both the size and cost of the whole system. This dissertation presents several advanced power amplifier solutions to provide wide-band and multi-band operations with efficiency improvement at power back-offs.
6
Dong, Zhao Yang. "Advanced methods for small signal stability analysis and control in modern power systems". Phd thesis, School of Electrical and Information Engineering, Graduate School of Engineering, 1998. http://hdl.handle.net/2123/6416.
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Yuan, Lin. "Design space re-engineering for power minimization in modern embedded systems". College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3651.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2006.Thesis research directed by: Electrical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Wang, Longfei. "High Performance Distributed On-Chip Voltage Regulation for Modern Integrated Systems". Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7590.
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Distributed on-chip voltage regulation where multiple voltage regulators are distributed among different locations of the chip demonstrates advantages as compared to on-chip voltage regulation utilizing a single voltage regulator. Better on-chip voltage noise performance and faster transient response can be realized due to localized voltage regulation. Despite the advantages of distributed on-chip voltage regulation, unbalanced current sharing issue can occur among each voltage regulator, which has been demonstrated to deteriorate power conversion efficiency, stability, and reliability of the power delivery network. An effective balanced current sharing scheme that can be applied to most voltage regulator types is proposed to balance the current sharing. Furthermore, a relatively high on-chip temperature induced by increased power density leads to prominent voltage regulator performance degradations due to aging. The emerging type of digital low-dropout regulator is investigated regarding aging induced transient and steady state performance degradations. Reliability enhancement techniques for digital low-dropout regulators are developed and verified. Such techniques introduce negligible power and area overhead and do not affect the normal operations of digital low-dropout regulators. Reliability enhancement techniques also reduce the area overhead needed to mitigate aging induced performance degradations. Area overhead saving further translates into more space for increased number of distributed on-chip voltage regulators, enabling scalable on-chip voltage regulation.
9
Chevalier, Samuel Chapman. "Inference, estimation, and prediction for stable operation of modern electric power systems". Thesis, Massachusetts Institute of Technology, 2021. https://hdl.handle.net/1721.1/130842.
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Thesis: Ph. D. in Mechanical Engineering and Computation, Massachusetts Institute of Technology, Department of Mechanical Engineering, February, 2021Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 261-277).
To keep pace with social-ecological disruptions and technological progressions, electrical power systems must continually adapt. In order to address the stability-related challenges associated with these adaptations, this thesis develops a set of analytically rigorous yet practically oriented methods for ensuring the continued stability of modern power systems. By leveraging inference, estimation, and predictive modeling techniques, the proposed methods capitalize on the unprecedented amount of real time data emerging from modernizing smart grids. For each method, we provide simulated test results from IEEE benchmark systems. Newly deployed Phasor Measurement Units (PMUs) are observing the presence of detrimental low frequency forced oscillations (FOs) in transmission grid networks. To begin this thesis, we address the problem of locating the unknown sources of these FOs.
To perform source identification, we develop an equivalent circuit transformation which leverages suitably constructed transfer functions of grid elements. Since FO sources appear in this equivalent circuit as independent current injections, a Bayesian framework is applied to locate the most probable source of these injections. Subsequently, we use our equivalent circuit to perform a systematic investigation of energy-based source identification methods. We further leverage this equivalent circuit transformation by developing "plug-and-play" stability standards for microgrid networks that contain uncertain loading configurations. As converter-based technology declines in cost, microgrids are becoming an increasingly feasible option for expanding grid access. Via homotopic parameterization of the instability drivers in these tightly regulated systems, we identify a family of rotational functions which ensure that no eigenmodes can be driven unstable.
Any component which satisfies the resulting standards can be safely added to the network, thus allowing for plug-and-play operability. High-fidelity linearized models are needed to perform both FO source identification and microgrid stability certification. Furthermore, as loss of inertia and real-time observability of grid assets accelerate in tandem, real-time linearized modeling is becoming an increasingly useful tool for grid operators. Accordingly, we develop tools for performing real-time predictive modeling of low frequency power system dynamics in the presence of ambient perturbations. Using PMU data, we develop a black-box modeling procedure, known as Real-Time Vector Fitting (RTVF), that takes explicit account for initial state decay and concurrently active input signals. We then outline a proposed extension, known as stochastic-RTVF, that accounts for the corrupting effects of unobservable stochastic inputs.
The surrogate modeling utilized by vector fitting can also be applied to the steady state power flow problem. Due to an unprecedented deployment of distributed energy resources, operational uncertainty in electrical distribution networks is increasing dramatically. To address this challenge, we develop methodology for speeding up probabilistic power flow and state estimation routines in distribution networks. We do so by exploiting the inherently low-rank nature of the voltage profile in these systems. The associated algorithms dynamically generate a low-dimensional subspace which is used to construct a projection-based reduced order model (ROM) of the full nonlinear system. Future system solves using this ROM are highly efficient.
by Samuel Chapman Chevalier.
Ph. D. in Mechanical Engineering and Computation
Ph.D.inMechanicalEngineeringandComputation Massachusetts Institute of Technology, Department of Mechanical Engineering
10
Phung, James Hon-Hoe. "Power Modeling in Modern Server Systems: An Examination of Various Novel Approaches". Thesis, The University of Sydney, 2019. https://hdl.handle.net/2123/21376.
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As Cloud and other distributed networks become more complex and new virtualization technologies are increasingly adopted, there is an increasing need for versatile solutions that can effectively measure the energy consumption incurred by users of such networks and use this information to schedule user jobs with the goal of maximizing energy efficiency. In this thesis, existing work in power modeling involving performance monitoring events and the Running Average Power Limit was reviewed. While substantial work has been done in these areas, the focus has been on a narrow range of use cases. To address the lack of versatility of existing power meters, three lightweight software-based virtual power meters were developed. Utilizing simple but powerful application-agnostic power models, they offer similar performances to existing power models but have minimal overheads and are portable for use in a variety of systems. The first two power meters use performance event counters and the RAPL feature respectively to estimate power use. The third power meter is an enhanced power meter incorporating features from these two earlier power meters. Additionally, the enhanced power meter can estimate power use on a per-application basis. Furthermore, a systematic framework PowerSave was developed to analyze and evaluate energy use and performance patterns for a variety of workloads for different types of server systems under different CPU power limits. Results from PowerSave and power modeling experiments show that CPU power use accounts for most of a server's power consumption and that there is a high level of correlation between CPU power use and server power use.
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Shridevi, Rajesh Jayashankara. "Emerging Security Threats in Modern Digital Computing Systems: A Power Management Perspective". DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7483.
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Design of computing systems — from pocket-sized smart phones to massive cloud based data-centers — have one common daunting challenge : minimizing the power consumption. In this effort, power management sector is undergoing a rapid and profound transformation to promote clean and energy proportional computing. At the hardware end of system design, there is proliferation of specialized, feature rich and complex power management hardware components. Similarly, in the software design layer complex power management suites are growing rapidly. Concurrent to this development, there has been an upsurge in the integration of third-party components to counter the pressures of shorter time-to-market. These trends collectively raise serious concerns about trust and security of power management solutions.
In recent times, problems such as overheating, performance degradation and poor battery life, have dogged the mobile devices market, including the infamous recall of Samsung Note 7. Power outage in the data-center of a major airline left innumerable passengers stranded, with thousands of canceled flights costing over 100 million dollars. This research examines whether such events of unintentional reliability failure, can be replicated using targeted attacks by exploiting the security loopholes in the complex power management infrastructure of a computing system.
At its core, this research answers an imminent research question: How can system designers ensure secure and reliable operation of third-party power management units? Specifically, this work investigates possible attack vectors, and novel non-invasive detection and defense mechanisms to safeguard system against malicious power attacks. By a joint exploration of the threat model and techniques to seamlessly detect and protect against power attacks, this project can have a lasting impact, by enabling the design of secure and cost-effective next generation hardware platforms.
12
Rens, Abraham Paul Johannes. "Validation of popular nonsinusoidal power theories for the analysis and management of modern power systems / by Abraham Paul Johannes Rens". Thesis, North-West University, 2005. http://hdl.handle.net/10394/1371.
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RINALDI, GIANMARIO. "Local and Wide-Area Sliding Mode State Observation, Fault Reconstruction and Control with Application to Modern Power Systems". Doctoral thesis, Università degli studi di Pavia, 2020. http://hdl.handle.net/11571/1326211.
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The present thesis summarises the research activity carried our by the PhD candidate Gianmario
Rinaldi from October 2016 to September 2019 at the Department of Electrical, Computer and Biomedical
Engineering at the University of Pavia, Italy.
In recent years, radical changes are taking place to power systems. A worldwide consensus has
been reached for the reduction of greenhouse effects, by promoting the growth of renewable energy
sources in power grids. Therefore, a special shared interest has been raised amongst researchers and
practitioners to turn the existing power grids into smarter and more reliable ones, which are able to
safely, efficiently, an reliably integrate the growing renewable energy sources.
Supervisory Control And Data Acquisition (SCADA) has been the conventional control and state
estimation methodology practically used in the last few decades. Recent progress in computer science
and electronic technologies has opened the door to the implementation of the so-called Wide Area
Measurement Systems (WAMS). In particular, with a widespread deployment of Phasor Measurement
Units (PMUs), a more accurate depiction of the state in power systems has become achievable
in practice.
Latest advances in computer science and electronic technologies have laid the groundwork for
the conception of the so-called cyber-attacks, which can be defined as computer-based algorithms
capable of destabilising the power network by compromising the collected measurements to be sent
to a control centre, attack the communication networks, or alter and delay the control variables.
In order to turn the existing power system into a smarter one capable of both harmoniously
integrating renewable power sources and efficiently and safely dealing with faults and cyber-attacks,
the attention is now focused on the following relevant research areas:
The design and assessment of more accurate, robust and dynamic state estimators in power systems,
which are able to obtain a near-real time depiction of all the state variables, instrumental
in enhancing the monitoring of the networks.
The implementation of timely fault detection, reconstruction and mitigation methodologies,
devoted to preserve the stability of the entire power network, thus preventing wide-spread
outages, blackouts, and degradations of the power quality.
The design of identification schemes to determine key-properties of the components in power
system context.
The design and assessment of novel control approaches devoted to both regulate the frequency
deviations and minimise the cost of the power generation. These control schemes are also required to be robust to possible faults, disturbances, and uncertainties affecting the power
systems.
The present thesis aims to fit into the aforementioned promising research areas in power systems. In
particular, four challenges are addressed:
The first addressed challenge considers the design of robust state estimators which are able to
depict in near real time the state of the overall power systems to globally enhance the monitoring
of the power systems, thus reducing the number of the deployed sensors. The undertaken
analysis started at the local level and then consider the power system as a large-scale system.
The second addressed challenge focuses on the design of fault detection, reconstruction, and
mitigation approaches devoted to enhance the resilience of the power network.
The third addressed challenge considers the design and the assessment of robust sliding mode
observer-based controllers which are capable of regulating the frequencies in power systems
whilst minimising the cost associated with the generators.
Finally, the fourth addressed challenges examines the identification of the relative degree properties
with application to electrical and power systems frameworks.
Furthermore, the outline of the present thesis is coherent with the development of the contributions
illustrated above.
14
Barik, Tapas Kumar. "Modern Adaptive Protection and Control Techniques for Enhancing Distribution Grid Resiliency". Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/103644.
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Power distribution systems have underwent a lot of significant changes in the last two
decades. Wide-scale integration of Distributed Energy Resources (DERs) have made the
distribution grid more resilient to abnormal conditions and severe weather induced outages.
These DERs enhance the reliability of the system to bounce back from an abnormal situation
rather quickly. However, the conventional notion of a radial system with unidirectional
power flow does not hold true due to the addition of these DERs. Bidirectional power flow
has challenged the conventional protection schemes in place. The most notable effects on
the protection schemes can be seen in the field of islanding or Loss of Mains(LOM) detection
and general fault identification and isolation. Adaptive protection schemes are needed to
properly resolve these issues. Although, previous works in this field have dealt with this
situation, a more comprehensive approach needs to be taken considering multiple topologies
for developing adaptive protection schemes. The most common protective devices widely
deployed in the distribution system such as overcurrent relays, reverse power relays at Point
of Common Coupling(PCC), fuses, reclosers and feeder breakers need to studied in implementing
these schemes.
The work presented in this dissertation deals with simulation based and analytical approaches
to tackle the issues of islanding and adaptive protection schemes. First we propose a multiprinciple
passive islanding detection technique which relies on local PCC measurements, thus
reducing the need of additional infrastructure and still ensuring limited Non Detection Zone
(NDZ). The next step to islanding detection would be to sustain a islanded distribution
system in order to reduce the restoration time and still supply power to critical loads. Such
an approach to maintain generator load balance upon islanding detection is studied next by
appropriate shedding of non-critical and low priority critical loads based upon voltage sensitivity
analysis. Thereafter, adaptive protection schemes considering limited communication
dependency is studied with properly assigning relay settings in directional overcurrent relays
(DOCRs), which are one of the most widely deployed protective devices in distribution
systems by catering to multiple topologies and contingencies. A simulation based technique
is discussed first and then an analytical approach to solve the conventional optimal relay
coordination problem using Mixed Integer Linear Programming (MILP) with the usage of
multiple setting groups is studied. All these approaches make the distribution more robust
and resilient to system faults and ensure proper fault identification and isolation, ensuring
overall safety of system.Doctor of Philosophy
With widespread integration of inverter-based distributed energy resources (DERs) in the distribution grid, the conventional protection and control schemes no longer hold valid. The necessity of an adaptive protection scheme increases as the DER penetration in the system increases. Apart from this, changes in system topology and variability in DER generation, also change the fault current availability in the system in real-time. Hence, the protection schemes should be able to adapt to these variations and modify their settings for proper selectivity and sensitivity towards faults in the system, especially in systems with high penetration of DERs. These protection schemes need to be modified in order to properly identify and isolate faults in the network as well as correctly identify Loss of Mains (LOM) or islanding phenomenon. Special attention is needed to plan the next course of action after the islanding occurrence. Additionally, the protective devices in distribution system should be utilized to their maximum capability to create an adaptive and smart protection system. This document elaborately explains the research work pertaining to these areas.
15
Brosius, Logan Robert Thomas. "On the Rise of China, The Reconfiguration of Global Power, and the Collapse of the Modern Liberal Order". Kent State University Honors College / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ksuhonors1453337681.
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Siebrits, Andre. "The role of great power war in the rise of Hegemons : a study of Dutch Hegemonic ascent in the modern world-system". Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/2787.
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Thesis (MA (Political Science))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: This study explores the claim that Great Power Wars are a necessary condition for successful hegemonic ascent in the modern world-system, primarily from the standpoint of World- Systems Analysis. This study advances the conception of hegemony primarily in economic and state terms, and it was investigated, by way of a historical case study, how the Thirty Years’ War (1618-1648) impacted the economic domains of agro-industrial production, commerce, and finance of the United Provinces of the Netherlands, and its main rival for systemic leadership, Hapsburg Spain. The variables utilised in the study were Great Power War, and the ‘material base’ of the state involved (both independent), the three abovementioned economic domains (intervening), and hegemony or defeat (dependent). The case study was primarily descriptive and explanatory, with the use of process-tracing in its compilation, and a method of within-case structured, focused comparison was utilised with the aim of tentatively producing standardised, generalised knowledge concerning the wider link between Great Power War and hegemony beyond the Dutch case. The findings of the study, although derived from only one historical case of hegemonic ascent in the modern world-system, strongly support the argument that Great Power War is necessary to secure the hegemony of the leading insular core state, which is physically removed from the fighting during the conflict, since the full mobilisation of its economy is effected, while the economies of most other core states are impaired, especially the main continental rival for hegemony. However, the ascending hegemon must also possess the requisite favourable ‘material base’. Further research on this topic is called for, given the potential destructiveness of a future Great Power War, and its role in establishing hegemony in the modern world-system.
AFRIKAANSE OPSOMMING: Hierdie studie ondersoek die bewering dat Groot Moontheid Oorloë ‘n noodsaaklike vereiste is vir suksesvolle hegemoniese bestyging in die moderne wêreld-sisteem, hoofsaaklik vanaf die standpunt van Wêreld-Sisteem Analise. Hierdie studie bevorder die konsepsie van hegemonie hoofsaaklik in ekonomiese en staat terme, en dit het ondersoek, deur middel van ‘n historiese gevallestudie, hoe die Dertig Jaar Oorlog (1618-1648) ingewerk het op die ekonomiese arenas van agri-industriële produksie, handel, and finansies van die Verenigde Provinsies van Nederland, en hul mededinger vir sistemiese leierskap, Spanje. Die veranderlikes wat in die studie ingespan was, was Groot Moontheid Oorlog, en die ‘materiële basis’ van die state in kwessie (onafhanlik), die drie bogenoemde ekonomiese arenas (albei tussenkomend), en hegemonie of nederlaag (afhanklik). Die gevallestudie was hoofsaaklik beskrywend en verduidelikend, en proses-nasporing (oftewel ‘process-tracing’) is in die samestelling daarvan benut, en ‘n metode van gestruktureerde, gefokusde vergelyking (oftewel ‘structured, focused comparison’) is gebruik binne die gevallestudie met die doel om tentatiewe gestandardiseerde en veralgemeende kennis te genereer wat bydra tot die verduideliking van die wyer skakel tussen Groot Moontheid Oorlog en hegemonie buite die geval van die Verenigde Provinsies. Die bevindinge van die studie, hoewel gegenereer aan die hand van slegs een historiese geval van hegemoniese bestyging in the moderne wêreld-sisteem, het sterk steun verleen aan die argument dat Groot Moontheid Oorloë nodig is om die hegemonie van die vernaamste insulêre kern staat te bewerkstellig, wat fisies verwyderd van die gevegte is tydends die oorlog, aangesien die volle mobilisasie van die ekonomie van hierdie staat bewerkstellig word, terwyl die ekonomieë van die meerderheid van die ander kernstate benadeel word, veral die vernaamste kontinentale mededinger om hegemonie. Die opkomende hegemoon moet egter ook oor die vereiste gunstige ‘materiële basis’ beskik. Verdere navorsing in hierdie veld word benodig, gegewe die waarskynlike vernietiging wat gesaai kan word deur ‘n toekomstige Groot Moontheid Oorlog, en die rol daarvan in die daarstelling van hegemonie in die moderne wêreld-sisteem.
17
Helbig, Achim, i Christoph Boes. "Electric Hydrostatic Actuation - modular building blocks for industrial applications". Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-200007.
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Electro Hydrostatic Actuators (EHA) are emerging as a viable option for industrial machine builders as the design combines the best of both electro-mechanical and electro-hydraulic technologies. The EHA is a highly integrated, compact alternative to traditional hydraulic solutions. Automation engineers moving toward electro-mechanical actuation in pursuit of energy efficiency and environmental cleanliness, will find an EHA an attractive option for high force density actuators. This paper will address the factors to consider when assessing an industrial machine’s application suitability for this latest innovation in actuation. It describes principal base circuits, a concept for EHA building blocks and a realized pilot application as well as challenges on actuator and components level.
18
Araujo, Ricardo Augusto de 1982. "Algoritmos para o planejamento da operação de sistemas modernos de distribuição de energia elétrica = Algorithms for operation planning of modern electric distribution power systems". [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259529.
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Orientador: Madson Cortes de AlmeidaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: O problema do planejamento da operação de redes de distribuição de energia elétrica consiste em determinar os ajustes para os taps dos transformadores e reguladores de tensão, para os bancos de capacitores e para as injeções de potências ativas e reativas dos geradores distribuídos e da subestação, obedecendo aos limites físicos e operacionais da rede, a fim de melhorar o seu desempenho. Este pode ser formulado como um problema de Fluxo de Potência Ótimo (FPO) bastante complexo, pois envolve fatores técnicos, como a regulação de tensão em regime permanente, e econômicos, como a redução de perdas e a valoração da energia fornecida por produtores independentes. Este trabalho propõe dois algoritmos para resolver o problema de planejamento da operação. No primeiro, é usado um algoritmo genético similar ao desenvolvido por Chu e Beasley, somado a um esquema especial de criação da população inicial. Este algoritmo pode prover soluções de boa qualidade e até mesmo a solução ótima global do problema. O segundo algoritmo é baseado na análise de sensibilidades e é capaz de encontrar soluções de boa qualidade a um custo computacional bastante inferior ao custo do algoritmo genético proposto. Além de poder ser aplicado no planejamento de curto-prazo da operação de modernas redes de distribuição de energia elétrica, os métodos propostos podem, por exemplo, auxiliar as concessionárias de energia elétrica na definição de condições para o estabelecimento de contratos com produtores independentes de energia. Os resultados apresentados, baseados nos sistemas de distribuição radiais de 34, 70 e 135 barras, mostram que os algoritmos propostos são promissores
Abstract: The distribution system operation planning stage is concerned with the determination of capacitor bank, transformer and voltage regulator settings. This must be accomplished considering active and reactive power injections of distributed generators and at the main substation, as well as physical and regulatory issues in order to improve the network performance. This is a quite complex Optimal Power Flow (OPF) problem because it involves technical factors such as steady state voltage regulation, economic factors such as losses reduction and energy bids from independent power producers. This work proposes two approaches to solve this operation planning problem. The first one uses a genetic algorithm similar to that developed by Chu and Beasley, however with a different strategy to create the initial population. This algorithm can provide good quality solutions and in some cases even optimal solutions. The second one is based on the use of sensitivities, where good quality solutions are obtained at low computing times, much lower than those obtained using the proposed genetic algorithm. Besides being applicable in short-term operation planning of distribution networks, the proposed methods could also assist the utility operator in setting up conditions for establishing contracts with independent power producers. The results presented here using radial distribution systems of 34, 70 and 135 buses demonstrated the potential of the proposed algorithms
Mestrado
Energia Eletrica
Mestre em Engenharia Elétrica
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Salles, Corrêa Diogo. "Methodology for evaluating the collective harmonic impact of residential loads in modern power distribution systems = Metodologias para a avaliação do impacto harmônico coletivo de cargas residenciais em modernos sistemas de distribuição de energia elétrica". [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261206.
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Orientador: Walmir de Freitas FilhoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: A penetração em massa de equipamentos eletrônicos de maior eficiência energética em residências está resultando em distorções significativas das formas de onda de tensão e corrente dos modernos sistemas de distribuição. Há uma necessidade crescente de técnicas que permitam determinar o impacto coletivo destas cargas residenciais nos níveis de distorção harmônica. Tais técnicas podem ser usadas, por exemplo, para prever os impactos da adoção em massa de lâmpadas fluorescentes compactas. Nesse contexto, esta tese de doutorado propõe uma técnica probabilística para avaliação do impacto dessas cargas residenciais na qualidade de energia tanto no primário como no secundário dos sistemas de distribuição de energia elétrica. O método modela individualmente e de forma estocástica as injeções harmônicas dos típicos eletrodomésticos a partir da distribuição da probabilidade de que cada aparelho seja ligado, a qual foi obtida a partir da pesquisa de dados de comportamento de carga. O resultado é um circuito elétrico equivalente harmônico variável no tempo representando uma casa residencial. Além disso, um modelo probabilístico para transformadores de distribuição foi desenvolvido através da combinação do transformador e das casas conectadas. Resultados de medições de campo confirmaram a validade da modelagem proposta. Em seguida, a metodologia proposta foi aplicada para investigar o impacto de tais cargas residenciais sobre a qualidade de energia dos sistemas de distribuição, tanto no primário como no secundário. Impactos como distorção harmônica na tensão e corrente; carregamento do transformador; elevação da tensão e corrente do neutro; interferência telefônica foram avaliados. A evolução dos impactos ao longo dos próximos anos, a partir de dados de tendências de mercado, também foi determinada. Adicionalmente, realizaram-se estudos para verificar a eficácia de duas soluções possíveis para mitigar distorção harmônica, sendo que a primeira consistiu em adotar os limites de emissão harmônica definidos pelo guia técnico IEC; e a segunda consistiu na instalação de filtros harmônicos no primário do sistema de distribuição
Abstract: The proliferation of electronic-based residential loads has resulted in significant harmonic distortion in the voltages and currents of distribution power systems. There is an urgent need for techniques that can determine the collective harmonic impact of these modern residential loads. Such techniques can be used, for example, to predict the harmonic effects of widespread adoption of compact fluorescent lights (CFLs). In response to this need, this PhD thesis proposes a versatile Monte Carlo simulation method for evaluating the potential impact of such residential loads on the harmonic levels of power distribution systems. The method models the random harmonic current injections of residential loads by simulating their operating states. This is done by determining the switch-on probability of a residential load based on load research results. The result is a time-varying harmonic equivalent circuit representing a residential house. By combining multiple residential houses supplied from a service transformer, a probabilistic model for service transformers is also derived. Field measurement results confirmed the validity of the proposed technique. The proposed methodology is applied to a typical distribution system for evaluating the impact of residential loads on several power quality aspects. The results of different case studies proved to be valuable in answering the following questions: (1) What are the potential power quality impacts of distributed nonlinear residential loads on primary and secondary power distribution systems? The example impacts include voltage distortion, zero sequence harmonics, neutral voltage/current rise, telephone interference, metering error, increased losses, overloading of distribution transformers. (2) How serious the impacts will become when more and more energy efficient appliances and consumer electronics penetrates into the residential loads? (3) If the consequence is of concern, what are the strategies and options available for utilities to manage the problem?
Doutorado
Energia Eletrica
Doutor em Engenharia Elétrica
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Anderson, Sharon Lee. "Reduced order power system models for transient stability studies". Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-09052009-040743/.
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Kaňovský, Jiří. "Energetické systémy v moderní výstavbě". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-221202.
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Altamirano, Chavez Armando. "An efficient algorithm using Householder's formulas for the solution of faulted power systems". Thesis, Kansas State University, 1986. http://hdl.handle.net/2097/9896.
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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.
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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.
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Le, Dantec Jorge I. (Jorge Ignacio). "Assessing business models arising from the integration of distributed energy systems in the Chilean electric power system". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90714.
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Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, Engineering Systems Division, System Design and Management Program, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 83-84).
Electric power systems are more than just networks of generation, transmission and distribution assets. They are socio-technical systems, involving regulation, markets and technology availability. Presently, the dynamic relation among these aspects is creating new consumer needs in many power systems around the world, which incumbent electricity utilities do not seem well suited to meet at the required pace. In this context, the integration of Distributed Energy Systems (DESs) and their related business models appears as a flexible and often more affordable option to deliver value, by fulfilling the unmet needs of both consumers and utilities. To advice Chilean electric power system's stakeholders about the adequacy of a set of DES-related business models to Chilean needs, this document presents a systematic analysis, which focuses on the interrelation between business model attributes, involved DES technologies, and stakeholder needs. Specifically, an analytic framework is developed and applied to some business models currently operative in other markets, measuring their adequacy to meet stakeholders' needs in a set of envisioned scenarios of Chile's power system. This work provides a systematic tool for decision-making processes in selecting business models, when the decision must be made with qualitative data. Moreover, the evaluation in the Chilean system of actual business models shows results that should be valuable for consumers, utilities, and regulators.
by Jorge I. Le Dantec.
S.M. in Engineering and Management
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Nteka, Makhetsi Flora. "Development and assessment of reduced order power system models". Thesis, Cape Peninsula University of Technology, 2013. http://hdl.handle.net/20.500.11838/1088.
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Thesis submitted in fulfilment of the requirements for the degree
Master of Technology: Electrical Engineering
in the Faculty of Engineering
at the Cape Peninsula University of Technology
2013The demand for electrical energy has kept on increasing, thus causing power systems to be more complex and bringing the challenging problems of electrical energy generation, transmission, stability, as well as storage to be examined more thoroughly. With the advent of high-speed computation and the desire to analyze increasingly complex behaviour in power systems, simulation techniques are gaining importance and prevalence. Nevertheless, while simulations of large, interconnected complex power systems are feasible, they remain time-consuming. Moreover, the models and parameters used in simulations are uncertain, due to measurement uncertainty, the need to represent a complex behaviour with low-order models, and the inherent changing nature of the power system. This research explores the use of a model reduction technique and the applications of a Real-Time Digital Simulator (RTDS) to reduce the uncertainty in large-scale complex power system models. The main goal of the research is to develop a reduced order model and to investigate the applications of the RTDS simulator in reduction of large, interconnected power systems models. The first stage of the study is to build and simulate the full model of the power system using the DigSILENT and RTDS simulators. The second phase is to apply model reduction technique to the full model and to determine the parameters in the reduced-order model as well as how the process of reduction increases this model uncertainty. In the third phase the results of the model reduction technique are compared based on the results of the original model - IEEE standard benchmark models has been used. The RTDS was used for comparative purposes. The thesis investigations use a particular model reduction technique as Coherency based Method. Though the method ideas are applicable more generally, a concrete demonstration of its principles is instructive and necessary. Further, while this particular technique is not relevant to every system, it does apply to a broad class of systems and illustrates the salient features of the proposed methodology. The results of the thesis can be used in the development of reduced models of complex power systems, simulation in real-time during power system operation, education at universities, and research. Keywords: IEEE benchmark models, reduced models, Coherency based Method, DigSILENT, RTDS, model uncertainty, power system stability
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Mazumdar, Joy. "System and method for determining harmonic contributions from nonlinear loads in power systems". Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/23215.
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The objective of this research is to introduce a neural network based solution for the problem of measuring the actual amount of harmonic current injected into a power network by an individual nonlinear load. Harmonic currents from nonlinear loads propagate through the system and cause harmonic pollution. As a result, voltage at the point of common coupling (PCC) is rarely sinusoidal. The IEEE 519 harmonic standard provides customer and utility harmonic limits and many utilities are now requiring their customers to comply with IEEE 519. Measurements of the customer’s current at the PCC are expected to determine the customer’s compliance with IEEE 519. However, results in this research show that the current measurements at the PCC are not always reliable in that determination. In such a case, it may be necessary to determine what the customer’s true current harmonic distortions would be if the PCC voltage could be a pure sinusoidal voltage. However, establishing a pure sinusoidal voltage at the PCC may not be feasible since that would mean performing utility switching to reduce the system impedance. An alternative approach is to use a neural network that is able to learn the customer’s load admittance. Then, it is possible to predict the customer’s true current harmonic distortions based on mathematically applying a pure sinusoidal voltage to the learned load admittance. The proposed method is called load modeling. Load modeling predicts the true harmonic current that can be attributed to a customer regardless of whether a resonant condition exists on the utility power system. If a corrective action is taken by the customer, another important parameter of interest is the change in the voltage distortion level at the PCC due to the corrective action of the customer. This issue is also addressed by using the dual of the load modeling method. Topologies of the neural networks used in this research include multilayer perceptron neural networks and recurrent neural networks. The theory and implementation of a new neural network topology known as an Echo State Networks is also introduced. The proposed methods are verified on a number of different power electronic test circuits as well as field data. The main advantages of the proposed methods are that only waveforms of voltages and currents are required for their operation and they are applicable to both single and three phase systems. The proposed methods can be integrated into any existing power quality instrument or can be fabricated into a commercial standalone instrument that could be installed in substations of large customer loads, or used as a hand-held clip on instrument.
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Hernandez, Michael. "Applications of modern control in power electronics". Paris 11, 2010. http://www.theses.fr/2010PA112161.
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Dans la première partie, cette dissertation continue le cadre pour l'analyse et la conception (probablement des compensateurs de facteur) de puissance (PF) non linéaire pour les systèmes électriques fonctionnant dans des régimes nonsinusoïdaux (mais périodiques) avec les charges non linéaires. En particulier, dans la prétention standard que le générateur est une source de tension sans l'impédance, nous avons caractérisé toutes les charges non linéaires dont le pf est amélioré avec un compensateur non linéaire indiqué. Et ce cadre est employé pour étudier le problème de lacompensation passive de pf d'un redresseur commandé par pont classique. Est donné le fonctionnement "à l'avance de phase" du redresseur qu'on s'attend à ce que la compensation capacitive améliore le pf. Il est cependant moins évident que ceci puisse également être réalisé (dans quelques conditions appropriées) avec des inducteurs. Dans la deuxième partie, on a proposé la méthodologie d’A pour concevoir les contrôleurs (PI) proportionnel-intégraux linéaires utilisés des applications de convertisseur de puissance et en assurant la stabilité asymptotique. La technique s’est fondée sur le fait de base que si un système d’affinage peut être rendu passif avec une commande constante, alors il est stabilisable avec pi. Un état structural a été imposé alors au convertisseur de puissance pour satisfaire l’ancienne propriété avec un résultat passif produit comme combinaison linéaire des états. Cette condition est technique et n’a aucune interprétation physique claire. Ce résultat est prolongé dans trois directions : d’abord, la condition mentionnée ci-dessus est enlevée ; en second lieu, une plus grande classe des convertisseurs (avec des sources extérieures de commutation) est considérée ; troisièmement, la résistance de charge est assumée qu’on propose l’inconnu et un contrôleur adaptatif de pi (avec trois estimateurs différents). La méthodologie est appliquée au problème de la compensation de facteur de puissance d’un redresseur triphasé de source de tension, avec des résultats de simulation proposés. En outre, pi adaptatif stable est conçu pour la régulation de tension de rendement d’un convertisseur quadratique de poussée montrant l’exécution au moyen de résultat expérimental. Dans la troisième partie quelques contrôleurs basés sur le concept de la commande de charge pour un convertisseur utilisé dans une mise sous tension la correction de facteur sont montrés. Le convertisseur se compose par le raccordement intercalé de deux convertisseurs ou plus de poussée reliée à la grille à l’aide d’un redresseur de diode non commandé. La commande de charge représente une solution bon marché pour garantir la mise en commun courante entre les différents convertisseurs impliqués, et est normalement employée en combination avec d’autres contrôleurs. Les deux contrôleurs sont d’abord conçus pour garantir le facteur de puissance de près d’un avec la tension CC Réglée, à laquelle la commande de charge est ajoutée pour distribuer le courant égal parmi les convertisseurs. En conclusion, on présente une simplification avec l’exécution semblable qui élimine l’utilisation des sondes courantes, excepté les transformateurs de courant exigés pour mettre en application la commande de charge, des résultats expérimentaux accomplissent cette cloison. La quatrième partie, présente l’exécution et la programmation d’une méthode pour dépister le point de puissance maximum (MPP) dans des applications (PV) photovoltaïques. Ce point de fonctionnement est d’intérêt spécial pendant qu’on l’exige pour extraire la puissance maximum disponible à partir des rangées photovoltaïquesIn the first part, this dissertation continues with the framework for analysis and design of (possibly nonlinear) power factor (PF) compensators for electrical systems operating in non-sinusoidal (but periodic) regimes with nonlinear loads. In particular, under the standard assumption that the generator is a voltage source with no impedance, we characterized all nonlinear loads whose PF is improved with a given nonlinear compensator. And this framework is used to study the problem of passive PF compensation of a classical half-bridge controlled rectifier. Given the “phase advance” operation of the rectifier it is expected that capacitive compensation improves PF, it is however less obvious that this can also be achieved (under some suitable conditions) with inductors. In the second part, A methodology to design linear proportional-integral (PI) controllers used in power converter applications and ensuring asymptotic stability was proposed. The technique relied on the basic fact that if an affine system can be rendered passive with a constant control, then it is stabilizable with a PL A structural condition was imposed then on the power converter to satisfy the former property with a passive output generated as a linear combination of the states. This condition is technical and has no clear physical interpretation. This result is extended in three directions : first, the aforementioned condition is removed ; second, a larger class of converters (with switching external sources) is considered ; third, the load resistance is assumed unknown and an adaptive PI controller (with three different estimators) is proposed. The methodology is applied to the problem of power factor compensation of a 3-phase. Voltage source rectifier, with simulation results proposed. Also, a stable adaptive PI is designed for the output voltage regulation of a quadratic boost converter showing the performance by means of experimental result. In the third part some controllers based on the concept of charge control for a converter used in an application of power factor correction are shown. The converter is composed by the interleaved connection of two or more boost converters connected to the grid by means of a non controlled diode rectifier. Charge control represents a cheap solution to guarantee current sharing among the different converters involved, and is normally used in combination with other controllers. The two controllers are first designed to guarantee the power factor close to one with regulated DC voltage, to which charge control is added to distribute equal current among the converters. Finally, a simplification with similar performance is presented that eliminates the use of current sensors, except for the current transformers required to implement the charge control, experimental results complete this part. The fourth part presents the implementation and programming of a method to track the maximum power point (MPP) in photovoltaic (PV) applications. This operation point is of special interest as it is required to extract the maximum power available from the photovoltaic arrays
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Hammer, Anders. "Analysis of IEEE Power System Stabilizer Models". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14035.
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Student:Anders HammerSupervisor:Kjetil UhlenContact:Daniel MotaCollaboration with:Voith HydroProblem descriptionIEEE (Institute of Electrical and Electronics Engineers) presented in 2005 a new PSS structure named IEEE PSS4B (Figure 0 1). Voith Hydro wants to analyse the pros and cons of using this new type compared to older structures. The PSS4B is a multi-band stabilizer that has three separate bands and is specially designed to handle different oscillation frequencies in a wide range. Until now, Voith Hydro has used the common PSS2B in their installations, but in the future they will probably start to implement the new PSS4B. This master thesis will seek to find an answer on following questions:•How should the PSS4B be tuned to give the best damping of the local and inter-area oscillation mode?•Will an implementation of PSS4B give a better result compared to PSS2B?•What are the pros and cons of PSS2B and PSS4B? Figure 0 1: The multi-band stabilizer, IEEE PSS4B [1].MethodIn order to test and compare different PSS models, a simple two-area network model is created in a computer simulation programme (SIMPOW). One of the generating units is a hydro generator, which has a model of a static excitation system made by Voith Hydro. This network is characterised by a poorly damped inter-area oscillation mode, and in addition some local oscillation modes related to each machine. Different PSS structures (PSS2B and PSS4B) are then tuned and installed in the excitation system of the hydro generator, in order to improve the stability of the network. Different tuning methods of the PSS4B are designed, tested and later compared with the more common stabilizer the PSS2B. Simplifications are made where parts of the stabilizer is disconnected in order to adapt the control structure to the applied network and its oscillations. Totally 5 different tuning methods are presented, and all these methods are based on a pole placement approach and tuning of lead/lag-filters. ResultsInitial eigenvalues of the different setups are analysed and several disturbances are studied in time domain analysis, in order to describe the robustness of the system. Figure 2 illustrates the rotor speed of the generator, where the different PSS’s are implemented. PSS4B is clearly resulting in increased damping of all speed oscillations in this network. The same results can also be seen in an eigenvalue analysis.Conclusion The best overall damping obtained in this master thesis occurs when the high frequency band of the PSS4B is tuned first, and in order to maximize the damping of the local oscillation mode in the network. The intermediate frequency band is then tuned as a second step, according to the inter-area oscillation mode. Results of this tuning technique show a better performance of the overall damping in the network, compared to PSS2B. The improvement of the damping of the inter-area oscillation mode is not outstanding, and the reason is that the applied machine is relative small compared to the other generating units in the network. The oscillation modes in the network (local and inter-area) have a relative small frequency deviation. A network containing a wider range of oscillation frequencies will probably obtain a greater advantage of implementing a multi-band stabilizer.
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Abur, Ali. "Knowledge-based power flow models and array processor-based power flow solutions for fast prediction of system states /". The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487261553057511.
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Scruggs, James N. "Power system availability determination through Petri net simulation". Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1178910568.
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Ha, Dinh Truc. "Line outage vulnerabilities of power systems : models and indicators". Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT018/document.
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La vulnérabilité des systèmes électriques est l'un des problèmes liés à leur complexité. Il a fait l’objet d’une attention croissante des chercheurs au cours des dernières décennies. Malgré cela, les phénomènes fondamentaux qui régissent la vulnérabilité du système ne sont pas encore bien compris.Comprendre comment la vulnérabilité des réseaux électriques émerge de leur topologie est la motivation principale du présent travail. Pour cela, le présent travail de recherché propose une nouvelle méthode pour évaluer la vulnérabilité des systèmes électriques et identifier leurs éléments les plus critiques. La méthode permet d’avoir une bonne compréhension des liens entre la topologie d’un réseau et sa vulnérabilité à des pertes d’ouvrages (lignes ou transformateurs).La première partie de ce travail consiste en une analyse critique des approches rencontrées dans la littérature, s’appuyant sur la théorie des graphes, pour analyser la vulnérabilité des réseaux électriques. Les résultats fournis par ces approches pour quatre réseaux IEEE sont comparés à ceux fournis par une analyse de contingence de référence, basée sur une résolution d’un load-flow AC. Des avantages et inconvénients de chaque approche est tirée une méthode améliorée pour l'évaluation de la vulnérabilité des réseaux électriques aux pertes d’ouvrage. Cette méthode est basée sur une approximation courant continue du load flow.La deuxième partie propose une nouvelle approche basée sur la théorie spectrale des graphes et son utilisation pour la résolution d’un load flow DC. Elle permet de mieux comprendre comment la vulnérabilité des réseaux électriques et leurs composants critiques émergent de la topologie du graphe sous-jacent au réseauThe vulnerability of electrical systems is one of the problems related to their complexity. It has received increasing attention from researchers in recent decades. Despite this, the fundamental phenomena that govern the vulnerability of the system are still not well understood.Understanding how the vulnerability of power systems emerges from their complex organization is, therefore, the main motivation of the present work. It proposes the definition of a standard method to assess the vulnerability of power systems and identify their most critical elements. The method enables a better understanding of the links between the topology of the grid and the line outage vulnerabilities.The first part of this research work offers a critical review of literature approaches used to assess system vulnerability. The results provided by these approaches for four IEEE test systems are confronted to a reference contingency analysis using AC power flow calculations. From these analyses, pros and cons of each approach are outlined. An improved method for assessment of system vulnerability to line outages is defined from this confrontation. It is based on DC load flow and graph theory.The second part proposes a new approach based on spectral graph theory and solving of DC power flow to identify how system vulnerability and critical components emerge from the power network topology
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Adepetu, Adeyemi (Adeyemi Adetayo). "Exploring neighborhood power production technologies and business models for developing economies". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/100087.
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Thesis: S.M., Massachusetts Institute of Technology, Engineering Systems Division, 2014."September 2014." Cataloged from PDF version of thesis.
Includes bibliographical references (pages 46-47).
A Neighborhood Power Producer business solution, which aggregates customers and therefore employs economies of scale, is one solution to the energy access issue of most developing economies. In this approach, entrepreneurs contract with a group of colocated residents or businesses to provide modem energy services. This service can be grid-tied or off-grid, serving as either backup power to the central electricity grid or as primary power, depending on access to the electric grid and/or the quality and availability of power. These systems are essentially micro-grids with distributed generation. These developing world Neighborhood Power Producers will also benefit from the rising demand for a more distributed electric grid as a solution to the threat of adverse weather like hurricanes and super storms in developed economies. Cyber security threats are also leading to increased research into distributed power generation systems. This provides technological advances that are powered by investments in developed markets. The developing economies can essentially leapfrog their more developed counterparts with regards to grid-resiliency. The goal of this thesis is to examine broad trends in the Neighborhood Power Producer business model and what strategies are necessary for business sustainability in the short, mid, and longer term.
by Adeyemi Adepetu.
S.M.
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Persson, Jonas. "Linear models of non-linear power system components". Licentiate thesis, KTH, Electrical Systems, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1415.
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Cresswell, Charles. "Steady state load models for power system analysis". Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/3846.
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The last full review of load models used for power system studies occurred in the 1980s. Since then, new types of loads have been introduced and system load mix has changed considerably. The examples of newly introduced loads include drive-controlled motors, low energy consumption light sources and other modern power electronic loads. Their numbers have been steadily increasing in recent years, a trend which is expected to escalate. Accordingly, the majority of load models used in traditional power system studies are becoming outdated, as they are unable to accurately represent power demand characteristics of existing and future loads. Therefore, in order to accurately predict both active and non-active power demand characteristics of aggregated modern power system loads in different load sectors (e.g. residential, commercial or industrial), existing load models should be updated and new models developed. This thesis aims to fill this gap by developing individual, generic and aggregated steady state models of the most common loads in use today, as well as of those expected to show significant growth in the future. The component-based approach is adopted for load modelling, where individual load models are obtained in detailed simulations of physical devices. Whenever possible, the developed individual load models are validated by measurements. These detailed individual load models are then simplified and expressed as equivalent circuit and analytical models, which allowed the establishment of generic load models that can be easily aggregated. It should be noted that since all non-active power characteristics are correctly represented, the developed aggregated load models allow for a full harmonic analysis, which is not the case with the standard steady state load models. Therefore, the proposed load models form an extensive library of comprehensive load models that are suitable for use in multiple areas of power system research. Based on the results of research related to typical domestic/residential sector load mix, the newly developed load models are aggregated and then applied to a typical UK/Scotland distribution network. Considerable differences are seen between network characteristics of newly proposed and previously developed models. The voltage distortion of a typical distribution system bus is investigated, and it is shown that distortion of the system voltage is likely to increase significantly in the future. The results of the presented research also suggest that neglecting the harmonic characteristics from the set of general load attributes may introduce errors in standard load flow studies.
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Hu, Boyang. "Design and Analysis of PV/Battery/EV in Modern Distribution Power System". Thesis, The University of Sydney, 2013. http://hdl.handle.net/2123/9896.
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In recent decades, power grids have been undergoing re-structuring gradually because of more and more renewable sources tied to grid. Two-way flows of electricity and information create an automated and intelligent electricity network.The broad aim of this thesis is to provide future utility providers and customers with new Smart-grid technologies to achieve a more intelligent, efficient, reliable and stable distribution power system. Research projects are based on the development of the new technologies of photovoltaics (PV), battery energy storage system (BESS), and electric vehicles (EV). Taking into account the abilities to both buck and boost the PV voltage, and designing the non-inverting characteristic for converter output polarity, this thesis proposes a new multiple inputs PV configuration that features effective accommodation of PV shading conditions and fast response to rapidly changing solar irradiations. A new interleaving technology is proposed for multiple inputs PV systems. It can effectively reduce the current ripples for parallel-connect, or voltage ripples for series-connect PV configurations, respectively. A new sizing method has been proposed for BESS. Conventional sizing methods simply assume the specific values of depth of discharge (DoD) and project lifetime years. However, different values of DoD can significantly affect the use of batteries. As well, a difference of one or two years in project lifetime may result in the need for an additional BESS replacement. A novel optimal scheduling method has been proposed for EV aggregators for both Grid to Vehicle (G2V) and Vehicle to Grid (V2G) applications. Unlike traditional scheduling methods, which only relate to G2V or V2G, the proposed bi-level optimization method simultaneously minimizes charging costs and gains reactive power support from EV chargers. The detailed investigation, design and verification results are presented in this thesis.
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Raoofsheibani, Davood [Verfasser]. "Online Power System Security Analysis and State Prediction : Enhanced Power System Models and Tools / Davood Raoofsheibani". Düren : Shaker, 2021. http://d-nb.info/1240853947/34.
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Vichare, Nitin Shrikrishna. "Robust Mahalanobis distance in power systems state estimation". Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/40024.
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Branney, Sean J. "Comparison and development of hurricane electrical power system damage models". Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/5657.
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Thesis (M.S.)--University of Missouri-Columbia, 2008.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 25, 2008) Includes bibliographical references.
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Du, Zhaobin, i 杜兆斌. "Area COI-based slow frequency dynamics modeling, analysis and emergency control for interconnected power systems". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B4175783X.
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Zhao, Long. "Novel Models and Algorithms for Uncertainty Management in Power Systems". Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4971.
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This dissertation is a collection of previously-published manuscript and conference papers. In this dissertation, we will deal with a stochastic unit commitment problem with cooling systems for gas generators, a robust unit commitment problem with demand response and uncertain wind generation, and a power grid vulnerability analysis with transmission line switching. The latter two problems correspond to our theoretical contributions in two-stage robust optimization, i.e., how to efficiently solve a two-stage robust optimization, and how to deal with mixed-integer recourse in robust optimization. Due to copyright issue, this dissertation does not include any methodology papers written by the author during his PhD study. Readers are referred to the author's website for a complete list of publications.
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Song, Shuaiwen. "Power, Performance and Energy Models and Systems for Emergent Architectures". Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/19316.
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Massive parallelism combined with complex memory hierarchies and heterogeneity in high-performance computing (HPC) systems form a barrier to efficient application and architecture design. The performance achievements of the past must continue over the next decade to address the needs of scientific simulations. However, building an exascale system by 2022 that uses less than 20 megawatts will require significant innovations in power and performance efficiency.A key limitation of past approaches is a lack of power-performance policies allowing users to quantitatively bound the effects of power management on the performance of their applications and systems. Existing controllers and predictors use policies fixed by a knowledgeable user to opportunistically save energy and minimize performance impact. While the qualitative effects are often good and the aggressiveness of a controller can be tuned to try to save more or less energy, the quantitative effects of tuning and setting opportunistic policies on performance and power are unknown. In other words, the controller will save energy and minimize performance loss in many cases but we have little understanding of the quantitative effects of controller tuning. This makes setting power-performance policies a manual trial and error process for domain experts and a black art for practitioners. To improve upon past approaches to high-performance power management, we need to quantitatively understand the effects of power and performance at scale.
In this work, I have developed theories and techniques to quantitatively understand the relationship between power and performance for high performance systems at scale. For instance, our system-level, iso-energy-efficiency model analyzes, evaluates and predicts the performance and energy use of data intensive parallel applications on multi-core systems. This model allows users to study the effects of machine and application dependent characteristics on system energy efficiency. Furthermore, this model helps users isolate root causes of energy or performance inefficiencies and develop strategies for scaling systems to maintain or improve efficiency. I have also developed methodologies which can be extended and applied to model modern heterogeneous architectures such as GPU-based clusters to improve their efficiency at scale.
Ph. D.
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Mirsad, Ćosović. "Distributed State Estimation in Power Systems using Probabilistic Graphical Models". Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2019. https://www.cris.uns.ac.rs/record.jsf?recordId=108459&source=NDLTD&language=en.
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We present a detailed study on application of factorgraphs and the belief propagation (BP) algorithm to thepower system state estimation (SE) problem. We startfrom the BP solution for the linear DC model, for whichwe provide a detailed convergence analysis. Using BPbasedDC model we propose a fast real-time stateestimator for the power system SE. The proposedestimator is easy to distribute and parallelize, thusalleviating computational limitations and allowing forprocessing measurements in real time. The presentedalgorithm may run as a continuous process, with eachnew measurement being seamlessly processed by thedistributed state estimator. In contrast to the matrixbasedSE methods, the BP approach is robust to illconditionedscenarios caused by significant differencesbetween measurement variances, thus resulting in asolution that eliminates observability analysis. Using theDC model, we numerically demonstrate the performanceof the state estimator in a realistic real-time systemmodel with asynchronous measurements. We note thatthe extension to the non-linear SE is possible within thesame framework.Using insights from the DC model, we use two differentapproaches to derive the BP algorithm for the non-linearmodel. The first method directly applies BP methodology,however, providing only approximate BP solution for thenon-linear model. In the second approach, we make a keyfurther step by providing the solution in which the BP isapplied sequentially over the non-linear model, akin towhat is done by the Gauss-Newton method. The resultingiterative Gauss-Newton belief propagation (GN-BP)algorithm can be interpreted as a distributed Gauss-Newton method with the same accuracy as thecentralized SE, however, introducing a number ofadvantages of the BP framework. The thesis providesextensive numerical study of the GN-BP algorithm,provides details on its convergence behavior, and gives anumber of useful insights for its implementation.Finally, we define the bad data test based on the BPalgorithm for the non-linear model. The presented modelestablishes local criteria to detect and identify bad datameasurements. We numerically demonstrate that theBP-based bad data test significantly improves the baddata detection over the largest normalized residual test.Glavni rezultati ove teze su dizajn i analiza novihalgoritama za rešavanje problema estimacije stanjabaziranih na faktor grafovima i „Belief Propagation“ (BP)algoritmu koji se mogu primeniti kao centralizovani ilidistribuirani estimatori stanja u elektroenergetskimsistemima. Na samom početku, definisan je postupak zarešavanje linearnog (DC) problema korišćenjem BPalgoritma. Pored samog algoritma data je analizakonvergencije i predloženo je rešenje za unapređenjekonvergencije. Algoritam se može jednostavnodistribuirati i paralelizovati, te je pogodan za estimacijustanja u realnom vremenu, pri čemu se informacije moguprikupljati na asinhroni način, zaobilazeći neke odpostojećih rutina, kao npr. provera observabilnostisistema. Proširenje algoritma za nelinearnu estimacijustanja je moguće unutar datog modela.Dalje se predlaže algoritam baziran na probabilističkimgrafičkim modelima koji je direktno primenjen nanelinearni problem estimacije stanja, što predstavljalogičan korak u tranziciji od linearnog ka nelinearnommodelu. Zbog nelinearnosti funkcija, izrazi za određenuklasu poruka ne mogu se dobiti u zatvorenoj formi, zbogčega rezultujući algoritam predstavlja aproksimativnorešenje. Nakon toga se predlaže distribuirani Gaus-Njutnov metod baziran na probabilističkim grafičkimmodelima i BP algoritmu koji postiže istu tačnost kao icentralizovana verzija Gaus-Njutnovog metoda zaestimaciju stanja, te je dat i novi algoritam za otkrivanjenepouzdanih merenja (outliers) prilikom merenjaelektričnih veličina. Predstavljeni algoritam uspostavljalokalni kriterijum za otkrivanje i identifikacijunepouzdanih merenja, a numerički je pokazano daalgoritam značajno poboljšava detekciju u odnosu nastandardne metode.
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Liu, Xinghua, i 刘兴华. "Power system operation integrating clean energy and environmental considerations". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43085866.
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Demiray, Turhan Hilmi. "Simulation of power system dynamics using dynamic phasor models /". Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17607.
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Holm, Gustav. "Automated Model Transformation for Cyber-Physical Power System Models". Thesis, KTH, Skolan för teknikvetenskap (SCI), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-214750.
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Standardized information and mathematicalmodels, which model the characteristics of the power generationand power transmission systems, are requirements for futuredevelopment and maintenance of different applications tooperate the electrical grid. Available databases such as Nordpoolprovides large amounts of data for power supply and demand [1].The typical misconception with open availability of data is thatexisting power system software tools can interact and process thisdata. Difficulties occur mainly because of two reasons. The firston is the amount of data produced. When the topology of theelectrical grid changes e.g. when a switch opens or closes, the flowof electrical power changes. This event produce changes ingeneration, transmission and distribution of the energy anddifferent data sets are produced. The second problem is therepresentation of information [2]. There are a limited number ofsoftware tools that can analyze this data, but each software toolrequires a specific data format structure to run. Dealing withthese difficulties requires an effective way to transform theprovided data representation into new data structures that canbe used in different execution platforms. This project aims tocreate a generic Model-to-Text (M2T) transformation capable oftransforming standardized power system information modelsinto input files executable by the Power System Analysis Tool(PSAT). During this project, a working M2T transformation wasnever achieved. However, missing functionality in someprograms connected to sub processes resulted in unexpectedproblems. This led to a new task of updating the informationmodel interpreter PyCIM. This task is partially completed andcan load basic power system information models.
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Cho, Bo Hyung. "Modeling and analysis of spacecraft power systems". Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/54741.
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A comprehensive large-scale power system modeling is developed to facilitate the design and analysis of present and future spacecraft power systems. A two-port coupling method is utilized to provide a modularity in model building and analysis of the system. The modular approach allows the model to be flexible, verifiable and computationally efficient. A methodology for the system level analysis is presented with the ability to focus on the performance characteristics of an arbitrary component or subsystem. The system performance parameters are derived explicitly in terms of the two-port hybrid g-parameter representation of the component or subsystem, and impedances of its terminating subsystems. From this, the stability of the system is analytically determined and the subsystem interaction criteria is observed. Also presented is a model development from the empirical data employing the complex curve fitting technique. The technique is especially powerful for large scale system modeling and analysis where certain components and subsystems are viewed as black boxes with measurable terminal characteristics. The technique can also be used to realize a reduced order model of a complex subsystem.
The Direct Energy Transfer (DET) spacecraft power system is modeled to demonstrate the versatility of the comprehensive system model by performing various DC, small-signal and large-signal analyses. Of particular interest is the analysis of the large-signal behavior of the nonlinear solar array system by employing the state-plane method. The analysis of the solar array system operation focused on the transition mode between the shunt mode and the battery discharging mode is presented. The subsystem interaction problems in the local component and global system are illustrated. A methodology for the design and trouble-shooting of a system dealing with the interaction problems using the g-parameters is described. Finally, a system level analysis of the DET system using an empirical data modeling technique is performed.Ph. D.
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Pourbeik, Pouyan. "Design and coordination of stabilisers for generators and FACTS devices in multimachine power systems /". Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09php877.pdf.
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Hecker, Rogelio Lorenzo. "Power feedback control in cylindrical grinding process". Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/16619.
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Roberts, Lewis George Wilson. "Parametric analysis of transient stability in power systems using classical models". Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.702145.
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This thesis aims to strengthen the bridge between mathematical and practical research into the transient stability of power systems. Literature that exploits the mathematical parallels between models for transient dynamics in power systems and the phenomenon of synchronisation in complex networks is explored. However, it is contended that research at the intersection of complex systems and power system stability can limit its applications to practical issues in power engineering. This thesis focuses on the measurement of transient stability in power systems in terms of a traditional stability metric for short-circuit faults on a power network, the critical clearing time (CCT). The CCT provides an upper bound on the duration of a short circuit on a power network before it is removed - cleared - by the action of protection mechanisms to isolate the faulted circuit such that the system will regain synchrony once the fault is cleared. Approaches that use energetic methods for assessing the transient stability of a power system are extended by developing metrics that can measure stability trends for different scenarios in a power system via the numerical continuation of equilibrium configurations under the variation of system parameters. An analytical CCT (ACCT) approximation is derived from this energetic framework in order to capture trends in stability with respect to a system parameter. The performance of the ACCT is compared to more accurate computations of CCT that use slower numerical simulation techniques. Attention is given to how well the ACCT approximation can capture stability trends under variation of key network design parameters such as load admittance and generator inertia. It is found for a two-machine infinite bus (TMIB) system that load parameter values that can improve stability can be identified using the ACCT. Also, the general dependence of a fault's CCT on the inertia of a generator in a TMIB power system is identifiable using the ACCT. For power systems with stationary generator inertia values, a method to provide a contingency analysis of fault locations is proposed. The method ranks the locations of short-circuit faults by their CCT; the more severe a fault the shorter its CCT. It is found in a TMIB system that the ACCT can identify the general location of severe faults under different inertia scenarios. It is shown that in larger power systems, energetic methods can be used to accurately identify the locations of faults with short CCTs. These results, together with relevant literature are used to suggest possible strategies to monitor transient stability within modern power systems.
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Landford, Jordan. "Event Detection Using Correlation within Arrays of Streaming PMU Data". PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/3031.
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This thesis provides a synchrophasor data analysis methodology that leverages both statistical correlation techniques and a statistical distribution in order to identify data inconsistencies, as well as power system contingencies. This research utilizes archived Phasor Measurement Unit (PMU) data obtained from the Bonneville Power Administration in order to show that this methodology is not only feasible, but extremely useful for power systems monitoring, decision support, and planning purposes.
By analyzing positive sequence voltage angles between a pair of PMUs at two different substation locations, an historic record of correlation is established. From this record, a Rayleigh distribution of correlation coefficients is calculated. The statistical parameters of this Rayleigh distribution are used to infer occurrences of power system and data events.
To monitor an entire system, a simple solution would be observing each of these parameters for every PMU combination. One issue with this approach is that correlation of some PMU pairs may be redundant or yield little value to monitoring capabilities. Additionally, this approach quickly encounters scalability issues as each additional PMU adds considerably to computation - for example, if the system contains n PMUs the amount of computations will be n(n-1)/2. System-wide monitoring of these parameters in this fashion is cumbersome and inefficient.
To address these issues, an alternative scheme is proposed which involves monitoring only a subset of PMUs characterized by electrically coupled zones, or clusters, of PMUs. These clusters include both electrically-distant and electrically-near PMU sites. When monitored over an event, these yield statistical parameters sufficient for detecting event occurrences. This clustering scheme can be utilized to significantly decrease computation time and allocation of resources while maintaining optimal system observability.
Results from the statistical methods are presented for a select few case studies for both data and power system event detection. In addition, determination of cluster size and content is discussed in detail. Lastly, the viability of monitoring pertinent statistical parameters over various clustering schemes is demonstrated.