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1
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
2
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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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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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.
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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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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.
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Du, Zhaobin, and 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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Золотова, Світлана Григорівна, Светлана Григорьевна Золотова, Svitlana Hryhorivna Zolotova, and L. Skubak. "System control in modern technology." Thesis, Видавництво СумДУ, 2008. http://essuir.sumdu.edu.ua/handle/123456789/16031.
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Manansala, Edgardo Celestino. "Adaptive power system control." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54391.
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This work presents a centralized control scheme applied to a power system. The scheme has adaptive characteristics which allow the controller to keep track of the changing power system operating point and to control nonlinear functions of state variables. Feedback to the controller is obtained from phasor measurements at chosen power system buses, generator field voltage measurements, and state estimators. Control effort is aimed at minimizing the oscillations and influencing the power system state trajectory through the control of linear and nonlinear functions of state variables during a power system disturbance.
The main contributions of this dissertation are the simultaneous introduction and utilization of measurement based terms in the state and output equations in the derivation and implementation of the control law, the study of limits on controller performance as the state residual vector becomes very large, and the simulation of the performance of local state estimators to prove the need for faster phasor measurement systems.
The test system is a hypothetical 39-Bus AC power system consisting of typical components which have been sufficiently modelled for the simulation of power system performance in a dynamic stability study.Ph. D.
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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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Tai-Cheng, Yang. "Power system stabilizer design." Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245278.
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Kreikebaum, Frank Karl. "Control of transmission system power flows." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50392.
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Power flow (PF) control can increase the utilization of the transmission system and connect lower cost generation with load. While PF controllers have demonstrated the ability to realize dynamic PF control for more than 25 years, PF control has been sparsely implemented.
This research re-examines PF control in light of the recent development of fractionally-rated PF controllers and the incremental power flow (IPF) control concept. IPF control is the transfer of an incremental quantity of power from a specified source bus to specified destination bus along a specified path without influencing power flows on circuits outside of the path.
The objectives of the research are to develop power system operation and planning methods compatible with IPF control, test the technical viability of IPF control, develop transmission planning frameworks leveraging PF and IPF control, develop power system operation and planning tools compatible with PF control, and quantify the impacts of PF and IPF control on multi-decade transmission planning.
The results suggest that planning and operation of the power system are feasible with PF controllers and may lead to cost savings. The proposed planning frameworks may incent transmission investment and be compatible with the existing transmission planning process. If the results of the planning tool demonstration scale to the national level, the annual savings in electricity expenditures would be $13 billion per year (2010$). The proposed incremental packetized energy concept may facilitate a reduction in the environmental impact of energy consumption and lead to additional cost savings.
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Sanchez, Ayala Gerardo. "Centralized Control of Power System Stabilizers." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/51754.
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This study takes advantage of wide area measurements to propose a centralized nonlinear controller that acts on power system stabilizers, to cooperatively increase the damping of problematic small signal oscillations all over the system. The structure based on decision trees results in a simple, efficient, and dependable methodology that imposes much less computational burden than other nonlinear design approaches, making it a promising candidate for actual implementation by utilities and system operators.
Details are given to utilize existing stabilizers while causing minimum changes to the equipment, and warranting improvement or at least no detriment of current system behavior. This enables power system stabilizers to overcome their inherent limitation to act only on the basis of local measurements to damp a single target frequency. This study demonstrates the implications of this new input on mathematical models, and the control functionality that is made available by its incorporation to conventional stabilizers.
In preparation of the case of study, a heuristic dynamic reduction methodology is introduced that preserves a physical equivalent model, and that can be interpreted by any commercial software package. The steps of this method are general, versatile, and of easy adaptation to any particular power system model, with the aggregated value of producing a physical model as final result, that makes the approach appealing for industry. The accuracy of the resulting reduced network has been demonstrated with the model of the Central American System.Ph. D.
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Toreid, Eivind. "Active Control of Reactive Power in a Modern Electrical Rail Vehicle." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-13863.
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Modern electrical rail vehicles employ four-quadrant voltage source converters, which allow independent control of real and reactive power. This thesis focuses the control of reactive power at the vehicle regarding load flow and stability.Settings for power factor as a function of voltage were proposed in a project fall 2010, aiming to reduce line loss and increase transmission capacity. This thesis is mainly a further investigation of some of the settings proposed.One of the proposed settings for controlling reactive power is found to reduce the load of a rotary converter station in the range of 0-3 %. Total system losses are reduced by 0.21-0.33 %.During traction, the problematic issue regarding stability is found to be speed oscillations of the rotary converter. Controlling reactive power is found to have a limited damping effect on speed oscillations of a rotary converter. Other works have investigated how speed oscillations of the rotary converter can be damped by controlling the real power of the vehicle; the real power control is found to have a clearly better effect than reactive.During no-load operation, the problematic issue regarding stability is found to be oscillations caused by the vehicle and its control system. The vehicle control system and its response to the line voltage may cause instability, especially at long line lengths, regardless of any rotary converter. As reactive power has a significant effect on the line voltage, reactive power may be controlled in a manner increasing the damping of such oscillations significantly.Finally the thesis describes how a simulation model of a modern electrical rail vehicle for stability analysis can be made from the steady state characteristics and the input admittance of the vehicle, without knowing the complete vehicle model.The settings which where proposed and investigated in this project are optimized for a system fed by stiff voltage sources, not by rotary converters, and a more complete optimization for a system fed by rotary converters would be of interest.
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Rohani, Mehdiabadi Behrooz. "Power control for mobile radio systems using perceptual speech quality metrics." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0174.
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As the characteristics of mobile radio channels vary over time, transmit power must be controlled accordingly to ensure that the received signal level is within the receiver's sensitivity. As a consequence, modern mobile radio systems employ power control to regulate the received signal level such that it is neither less nor excessively larger than receiver sensitivity in order to maintain adequate service quality. In this context, speech quality measurement is an important aspect in the delivery of speech services as it will impact satisfaction of customers as well as the usage of precious system resources. A variety of techniques for speech quality measurement has been produced over the last few years as result of tireless research in the area of perceptual speech quality estimation. These are mainly based on psychoacoustic models of the human auditory systems. However, these techniques cannot be directly applied for real-time communication purposes as they typically require a copy of the transmitted and received speech signals for their operation. This thesis presents a novel technique of incorporating perceptual speech quality metrics with power control for mobile radio systems. The technique allows for standardized perceptual speech quality measurement algorithms to be used for in-service measurement of speech quality. The accuracy of the proposed Real-Time Perceptual Speech Quality Measurement (RTPSQM) technique with respect to measuring speech quality is first validated by extensive simulations. On this basis, RTPSQM is applied to power control in the Global System for Mobile (GSM) communication and the Universal Mobile Telecommunication System (UMTS). It is shown by simulations that the use of perceptual-based power control in GSM and UMTS outperforms conventional power control in terms of reducing the transmitter signal power required for providing adequate speech quality. This in turn facilitates the observed increase in system capacity and thus offers better utilization of available system resources. To enable an analytical performance assessment of perceptual speech quality metrics in power control, the mathematical frameworks for conventional and perceptual-based power control are derived. The derivations are performed for Code Division Multiple Access (CDMA) systems and kept as generic as possible. Numerical results are presented which could be used in a system design to readily find the Erlang capacity per cell for either of the considered power control algorithms.
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Shafie-Pour, A. R. "Real-time power system security assessment." Thesis, Durham University, 1989. http://etheses.dur.ac.uk/9303/.
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The increasing complexity of modern power systems has led to a greater dependence on automatic control at all levels of operation. Large scale systems of which a power system is a prime example, is an area in which a wide gap exists between theoretical mathematically based research and engineering practice. The research programme at Durham is directed towards bridging this gap by linking some of the available and new theoretical techniques with the practical requirements of on-line computer control in power systems. This thesis is concerned with the assessment of security of power systems in real-time operation. The main objective of this work was to develop a package to be incorporated in the University of Durham On line Control of Electrical Power Systems (OCEPS) suite to cater for network islanding and analyse the features and the feasibility of a real-time 'security package’ for modern energy control centres. The real-time power systems simulator developed at Durham was used to test the algorithms and numerical results obtained are presented.
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Mehta, Mehul. "Power control for a mobile satellite system." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245306.
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Ilutu, Danny Makimi. "Linear power control system for a nanosatellite." Thesis, Cape Peninsula University of Technology, 2011. http://hdl.handle.net/20.500.11838/2202.
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Thesis (MTech(Electrical Engineering))--Cape Peninsula University of Technology, 2011.Nanosatellite is an electronic device that requires a steady and reliable electrical power supplier (EPS) in order to drive all its electronic circuits. Its unpredictable failures can lead to extensive financial and time losses. The failures may be owing to the environment in which the satellite operates; the technique and the method used to generate power. In order to effectively minimise the risk of the EPS failures, a better technique is essential. The direct energy transfer (DET) technique was chosen for this research because it provides high efficiency and high reliability, unlike the maximum power point tracking (MPPT) technique, which obtains maximum power from the solar cells by using a microcontroller. DET works on a fixed working point of current-voltage characteristic and responds to all satellite power system requirements. The microcontroller is not a suitable device in satellite electrical power systems that requires high reliability, but is used because it is difficult to track the maximum power of solar cells without it. The analog MPPT system is another option, but the technique requires discrete components. Its deployment is limited because of the system's operating frequency and large electronic components such as the inductor and capacitor.
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Looja, Tuladhar R. "Control of Custom Power System using Active Disturbance Rejection Control." Cleveland State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=csu1438913443.
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Lord, David Allan. "Power applied to purpose : environmental control and the shape of modern architecture." Thesis, University College London (University of London), 1987. http://discovery.ucl.ac.uk/10062867/.
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The idea is developed that environmental control systems - lighting, heating, ventilation and acoustics - are elements of architectural meaning with strong links to the shape of buildings. The resulting architecture of the well-tempered environment is aesthetic and semantic as well as functional and technologicaL Lyrical and technical elements of well-tempered architecture are examined and the origin of environmental tempering in Western culture is traced. The study begins with classical Greek and Roman examples, continuing with folk traditions and the development of the science of architecture. In each instance, building types are described which illustrate the impact of environmental tempering techniques and functions on the shape of architecture. Classical examples include the Roman villa, bath and theatre. Later building types are prisons, hospitals, factories, theatres and galleries. Thus, a repertoire of climatically responsive forms is examined. The idiom is illustrated during the Modern era by the designs of four architects -- Frank Lloyd Wright, Le Corbusier, Alvar Aalto and Louis I. Kahn. Their works mark a zenith in the integration of architectural form with environmental tempering. The final chapter surveys the architecture of environmental tempering since the Modern Movement, including Regionalist, LateModernist, High-Tech and Post-Modernist examples. The conclusion proposes a definition of an architecture based on the art and science of environmental tempering.
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Banerjee, Abhishek. "Resilient Monitoring and Robust Control towards Blackout Prevention in Modern Power Grids." Diss., North Dakota State University, 2020. https://hdl.handle.net/10365/31778.
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This dissertation embodies a comprehensive approach towards resilient monitoring of frid events using Structure Preserving Energy Functions (SPEFs) and introduces a novel control architecture in Multi Terminal Direct Current (MTDC) grids, for inter-area oscillation damping and achieving robustness to AC as well as DC side, post-contingency events in the modern power grid. This work is presented as a collection of several publications which investigate and address the proposed research topics. At first, SPEFs are derived for multi-machine IEEE benchmark models with the help of the Wide-Area Measurements (WAMs). A physics-based hybrid approach to develop one-to-one mapping between properties of energy function components with respect to the type of fault in the system is introduced. The proposed method is tested offline on a IEEE-39 bus, New England Test System (NETS), with particular interest in monitoring the most sensitive energy functions during relay misoperations. Such events can be precipitated by zone 3 trips in distance relays due to load encroachment during stressed conditions. These might include a genuine misoperation, a false trip due to cyber-attacks, or a load encroachment, all of which are undesirable under normal operating circumstances. An online monitoring scheme is introduced in an actual blackout simulation in the Western Electricity Coordinating Council (WECC) to examine what further indications these energy function components can provide, especially during a cascading sequence, and how they could supervise critical tripping decisions by distance relays. Next, a futuristic grid comprised of Voltage Source Converter (VSC) based AC-MTDC is considered due to its recent proliferation in integrating offshore wind farms to onshore grids, and additionally improving strength of weak AC grids. A robust control is designed using the converter station poles as actuators to provide damping support to the surrounding AC grid. Further, a design problem is envisioned and implemented that introduces disturbance rejection into control architecture by designing a novel explicitly modeled disturbance plant in the Linear Matrix Inequality (LMI) framework. Finally, a novel robust inter-area oscillation damping controller is designed that proves its effectiveness in inter-area mode settling times, and provides robustness to (n-1) contingencies in the AC as well as the DC side of the meshed AC-MTDC grid.
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Cimen, Hasan. "Decentralised power system load frequency controller design." Thesis, University of Sussex, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244317.
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Yogendran, G. Henry. "Real time digital control system for power system analog simulator." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ53246.pdf.
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Jamal, Wissam. "Application of modern control techniques in AC speed drive system." Thesis, Swansea University, 2002. https://cronfa.swan.ac.uk/Record/cronfa42544.
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In the past, Direct Current (dc) machines have been commonly favoured in areas where a precise variable speed operation is highly required. This is due to the feasible linear control of flux and torque, which is accomplished by simply varying the field and armature currents. However, they are bulky, expensive and require periodic maintenance due to the existence of commutators and brushes. Alternating Current (ac) machines particularly the squirrel cage induction type have emerged as an alternative to those of dc machines in the application of speed drive systems. In general, however, they do require more complex control schemes than the dc motors, because of their highly non-linear dynamic structure with strong dynamic interactions. This situation has changed dramatically over the last few years with the advent of fast switching power converters along with high performance micro-controllers, which made a significant contribution to performance enhancement of modem speed drive systems. In addition, various control techniques have made possible the application of induction motors in high performance speed drive operations where traditionally only dc motors were previously available. On the other hand, in many speed drive applications which incorporate either scalar or vector control, the prime objective of the speed controller is the capability of achieving a good speed tracking performance and without sensitivity to parameters and operating condition changes. For these reasons, comprehensive investigation of state-of-the-art modem control schemes, which include fuzzy logic and sliding mode control are discussed. The main principles underlying fuzzy logic and sliding mode control schemes along with their basic theory and general mathematical representation are reviewed. In addition, the application of fuzzy logic concepts to reduce the chattering phenomenon typically inherited in the sliding mode control is successfully presented, which results in a new integrated fuzzy sliding mode control algorithms. Through extensive simulation studies, it is found that the fuzzy logic control scheme attained a good transient performance for the speed drive system in comparison to the conventional sliding mode control and the new integrated fuzzy sliding mode control. Furthermore, the design simplicity of the fuzzy logic control system has made it virtually attractive for the ease of practical implementation of the proposed drive system. Extensive practical testes of the proposed variable speed drive system have been carried out to verify the validity of the simulation analysis of the proposed fuzzy logic control system. Several tests are conducted in order to bring out the effectiveness of the designed control system upon step change in speed command and impact load disturbances. The digital implementation of the proposed fuzzy logic control algorithms is realised on a single chip, Intel 80C196KC 16-bit embedded microcontroller, a low cost derivative of the MCS-96 architecture. The main contribution of this thesis is the novel approach to design a sliding mode control system using concepts from fuzzy logic algorithms to alleviate the chattering problems and improve the dynamics of the induction motor drive.
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Oukati, Sadegh Mahmoud. "Control of power electronic devices (FACTS) to enhance power system stability." Thesis, University of Strathclyde, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275177.
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Roddis, Roge. "Evaluation of modern control system design techniques for a multivariable electro-hydraulic system." Thesis, Sheffield Hallam University, 2000. http://shura.shu.ac.uk/20288/.
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An experimental apparatus has been developed with the object of providing a test plant, based on commercially available electro-hydraulic components, for the investigation of multivariable control system design methodologies. A mathematical model has been produced for this experimental plant and a preliminary analysis of the plant carried out. A selection of controller design techniques has been investigated. Designs have been produced for two state feedback controllers in which the feedback coefficients were based on LQR theory, one of which used a full order estimator based on a Kalman Filter, the other using a reduced order observer whose poles were chosen arbitrarily. In addition, forward path compensators have been developed using the Characteristic Locus and the Hinfinity/Mixed Sensitivity methods. These controller designs were based on computations and simulations utilising Matlab and a selection of its control engineering toolboxes and Simulink. The completed designs were implemented in digital form and tested on the actual plant. A series of tests were carried out to assess the robustness of the various controllers in the presence of plant uncertainty. The physical plant was modified and the controllers based on the nominal plant model used in conjunction with this modified plant. As a design technique which enabled robustness issues to be addressed explicitly, the Hinfinity approach was used to improve the robustness of the original Hinfinity controller.
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Flath, Allen III. "Mathematical Programming Approach for the Design of Satellite Power Systems." UKnowledge, 2019. https://uknowledge.uky.edu/ece_etds/136.
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Satellite power systems can be understood as islanded dc microgrids supplied by specialized and coordinated solar cell arrays augmented by electrochemical battery systems to handle high-power loads and periods of eclipse. The periodic availability of power, the limited capacity of batteries, and the dependence of all mission service on power consumption create a unique situation in which temporal power and energy scarcity exist. A multi-period model of an orbital satellite power system’s performance over a mission’s duration can be constructed. A modular power system architecture is used to characterize the system’s constraints. Using mathematical programming, an optimization problem can be posed such that the optimal power and energy ratings for the power system are determined for any load schedule imposed by a given mission’s requirements. The optimal energy trajectory of the electrical power system over a mission’s duration is also determined when the mathematical programming problem is solved. A generic set of mission requirements is identified to test this approach, but the objective function of the resulting optimization problem can be modified to return different results. These results can provide a clear illustration of the trade-offs that designers of such power systems consider in the design process.
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De, Arizon Paloma. "Online power system security classifier and enhancement control." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0020/NQ48625.pdf.
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Peck, Nathan J. "PEAK POWER CONTROL WITH AN ENERGY MANAGEMENT SYSTEM." Monterey, California. Naval Postgraduate School, 2013. http://hdl.handle.net/10945/32884.
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The Department of Defense (DoD) is researching methods to enhance energy security and reduce energy costs. The energy security of DoD installations relies on the commercial electricity grid. One method being considered to improve energy security and reduce energy costs is microgrids that include combinations of energy storage, energy sources, critical loads, and non-critical loads. A microgrids power demand and the benefits of a microgrid integrated with a power electronics enabled Energy Management System (EMS) is investigated in this thesis. The power demand of a single family household is analyzed. The peak power demand of the single family household displays the drawbacks of peak power demand on the commercial electricity grid and the installations receiving power from it. Drawbacks include reduced energy security due to blackouts and increased cost as a result of meeting the peak demand. One benefit of an EMS is its ability to island or continue supplying power to critical loads when the commercial electricity grid is lost. A second benefit is reduced power demand on the commercial electricity grid during peak power demand or on distributed resources (DR) while islanded by performing peak power control. The performance of peak power control by an EMS is demonstrated using a Simulink model and an experimental laboratory setup. The Simulink model and EMS functionality are validated with the laboratory experiments. The Simulink model is then used to demonstrate the reduction in peak power demand on the commercial electricity grid using an EMS on more complex loads such as motors and diode rectifiers. The Simulink model is also used to compare the power demand on the commercial electricity grid with and without the EMS.
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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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Abdelaal, Ashraf Khalil Ibrahim. "Expert system applications to electrical power system voltage control and security." Thesis, University of Strathclyde, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366882.
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Cheung, Siu-pan. "Direct transient stability margin assessment of power system with excitation control and SVC control /." Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1753706X.
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Burt, Graeme M. "An expert system approach to on-line fault diagnosis in power system networks." Thesis, University of Strathclyde, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340000.
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Yao, Bo 1968. "Priority mechanism for QoS control in CDMA system through dynamic power control." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79272.
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Future wireless systems will have to support multimedia services such as voice, data and video. Issues in providing multimedia services on wireless systems include multiple access, bandwidth rationing, scheduling and power control. In this thesis, we address the last issue. CDMA is assumed to be the access method. Each of these services has different Quality of Service (QoS) requirements, maximum power and packet time-out constraints; in order to achieve the required QoS, they can alter their transmission. In this work, we present a novel Power Control With Priority Scheduling (PCWPS) algorithm for a wireless CDMA system, which achieves reliability and efficiently control packet loss due to timeout violation for simultaneously transmitted multimedia traffic, as well as minimizing system total interference. Our power control algorithm requires information about each traffic class instant state, as well as the wireless channel condition at the beginning power update iteration. Based on this information, the optimum allocated power can be calculated through linear or nonlinear programming methods. The simulation results show that our algorithm achieves good performance in term of packet loss due to timeout.
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張小彬 and Siu-pan Cheung. "Direct transient stability margin assessment of power system with excitation control and SVC control." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31212979.
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Thompson, John Gerard. "Emergency control of frequency in an isloated power system." Thesis, Queen's University Belfast, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334492.
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Uurtonen, Tommi. "Optimized Power Control for CDMA System using Channel Prediction." Thesis, Linköping University, Department of Science and Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-3697.
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In an optimal power control scheme for a Code Division Multiple Access (CDMA) system all mobile stations signals should arrive to the base station at equal power. If not, stronger singals may cause too much interference and block out weaker ones. Commonly used power control schemes utilizes the Signal to Interference Ratio (SIR) to design a Power Control Command (PCC) to adjust the transmit power of the mobile station. A significant problem within the conventional methods is the slow SIR recovery due to deep channel fades. Conventional methods base the PCC on the previous channel state when in fact, the channel state may have significantly changed when transmission occurs. These channel changes may cause the SIR to drop or rise drastically and lead to uncontrollable Multi Access Interference (MAI) resulting in power escalation and making the system unstable. In order to overcome power escalation and improve the recovery from deep fades a novel power control method has been developed. Based on Linear Quadratic Control and Kalman filtering for channel prediction this method designs the PCC based on the coming channel state instead of the current. This optimizes the PCC for the channel state where transmission occurs. Simulations show that this control scheme outperforms previous methods by making the impacts of the deep fades less severe on the SIR and also improves the overall SIR behaviour.
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Kalitjuka, Tatjana. "Control of Voltage Source Converters for Power System Applications." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14370.
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The research work is aimed on the investigation of possible modeling and control schemes for the dc-link of VSC, with the purpose of identifying the impact of such modeling and control on the dynamics of the conversion system. A system consisting of back-to-back converters with equivalent grid interconnection and source representation is designed in the software PSCAD/EMTDC using a detailed switching model of the inverter and rectifier components. The control technique based on the well-established concept of vector control is implemented. The main task of the master thesis is oriented towards the achievement of more reliable dc-link dynamics with smaller required capacitance. The control algorithm is based on balancing the power between inverter and rectifier through the dc-link with the minimum dc voltage variations. Dc-link voltage regulation is achieved by implementing a control based on the energy stored in the dc-link capacitor. Alignment to a dq synchronous reference frame orientation with PI regulators is used in the control philosophy for decoupling purposes.
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Mensah, Edoe F. Kwatny Harry G. "Logic-based optimal control for shipboard power system management /." Philadelphia, Pa. : Drexel University, 2008. http://hdl.handle.net/1860/2765.
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Xu, Yan. "Dynamic security assessment and control of modern power systems using intelligent system technologies." Thesis, 2013. http://hdl.handle.net/1959.13/939734.
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Research Doctorate - Doctor of Philosophy (PhD)Security is a basic yet essential requirement for operating a power system. Due to the continuous growth of load demand and unmatched infrastructure investment, modern power systems are being pushed to operate closer to their security boundary. This research focuses on the dynamic security analysis of power systems, which involves examining different stability criteria when the power system is subjected to a sudden disturbance. Conventional methods are mainly based on time-domain simulation technique, which usually suffers from insufficiently fast speed and inability to provide useful information about system dynamic characteristics and guidelines for control. Using intelligent system (IS) technologies, this research developed a series of new methods, which can effectively overcome the shortcomings of the conventional approaches. In the area of dynamic security assessment (DSA), an extreme learning machine (ELM)-based real-time DSA model is developed at first. The model is much faster in learning speed and hence can be on-line updated for performance enhancement. Subsequently, based on ensemble learning theory, an IS composed by multiple ELMs is developed for more accurate and reliable DSA. This IS is able to filter out potentially inaccurate results, when combined with a traditional DSA tool such as time-domain simulation it can enable reliable and real-time DSA. At last, an intelligent DSA framework is proposed for power systems with large-scale wind power. The proposed framework is able to accommodate fast changes of system operation condition due to the imbedded intermittent wind power generations. In the area of dynamic security control (DSC), methods for preventive transient stability control and emergency frequency stability control are developed. Specifically, a hybrid method for transient stability-constrained optimal power flow (TSC-OPF) is proposed, which is able to able to rigorously satisfy the transient stability constraints and efficiently search the global optimal solution. Subsequently, for more transparent and interpretable preventive control, two new methods based on decision tree (DT) and pattern discovery (PD) techniques are proposed, respectively. The DT-based method can infer stability control rules and the PD-based method is able to identify (statistically) the stable region, which are both interpretable for practical use. When combined with an OPF tool, efficient and transparent preventive control can be realized. Finally, emergency control against frequency instability is studied. A method for real-time predicting event-driven load shedding is proposed. The proposed algorithms and methodologies have all been successfully demonstrated on a number of benchmark test systems and compared with existing proposals in the literature (when applicable). Simulation results have verified their effectiveness and superiority over compared approaches.
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Krishan, Ram. "Stability and optimization of ac/dc power systems." Thesis, 2018. http://localhost:8080/xmlui/handle/12345678/7707.
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Gumede, Nkosinomusa S. "Eskom-ZESA interconnected power system modelling." Thesis, 2016. http://hdl.handle.net/10539/21110.
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A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering, 2016The power system frequency must be kept as close as possible to the nominal value. This is due to the inherent design of electrical equipment to operate efficiently at the nominal frequency. Frequency regulation in an interconnected power system is the duty of all members of the interconnection. However, in the Eskom-ZESA interconnected power system Eskom engineers ignore the contribution of the ZESA system to primary frequency control. This is mainly due to the prevalent assumption that the ZESA control area is small relative to the Eskom control area and its contribution to primary frequency control of the interconnected power system is negligible. This document presents a project that examines the validity of this assumption via determination of the contribution of the ZESA system to the interconnected power system’s primary frequency control. The interconnected power systems background was studied to understand the theory behind the operation of two or more interconnected power systems. System frequency disturbances deemed to be a good representation of the Eskom-ZESA interconnected power system’s performance were selected and analysed to validate the current assumption. The results show that there is a significant support from ZESA during a system frequency disturbance. This proves that the existing assumption is not valid anymore. Furthermore; the generator model that mimics the Eskom-ZESA tie-line governing behaviour was developed. Two different types of governor models were employed; firstly the IEEEG1 governor was tuned to control generator output to match the tie-line performance and then the TGOV5 governor model was used. The IEEEG1 governor model is a simplified governor representation; as a result, it is not easy to tune the parameters to match tie-line response. However, the performance is acceptable and it can be used to represent the tieline governor response. The TGOV5 governor model is very complex as discussed in section 4.2. The model includes boiler dynamics, and this improves performance such that it is possible to tune the parameters to follow the tie-line performance as close as necessary.
GR2016
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Pourbeik, Pouyan. "Design and coordination of stabilisers for generators and FACTS devices in multimachine power systems / by Pouyan Pourbeik." Thesis, 1997. http://hdl.handle.net/2440/18969.
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Bibliography: leaves 238-248xxix, 248 leaves : ill. ; 30 cm.
This thesis is concerned with the design and coordination of linear, fixed parameter controllers for the purpose of enhancing the dynamic performance of a multimachine power system. The studies are based on linear control theory and involve state space analysis, modal analysis, eigenanalysis and conventional frequency response techniques. The emphasis is on the small-signal performance of the system
Thesis (Ph.D.) -- University of Adelaide, Dept. of Electrical and Electronic Engineering, 1997?
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Vaezi, Masoud. "Modeling and control of hydraulic wind power transfer systems." Thesis, 2014. http://hdl.handle.net/1805/6172.
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Indiana University-Purdue University Indianapolis (IUPUI)Hydraulic wind power transfer systems deliver the captured energy by the blades to the generators differently. In the conventional systems this task is carried out by a gearbox or an intermediate medium. New generation of wind power systems transfer the captured energy by means of high-pressure hydraulic fluids. A hydraulic pump is connected to the blades shaft at a high distance from the ground, in nacelle, to pressurize a hydraulic flow down to ground level equipment through hoses. Multiple wind turbines can also pressurize a flow sending to a single hose toward the generator. The pressurized flow carries a large amount of energy which will be transferred to the mechanical energy by a hydraulic motor. Finally, a generator is connected to the hydraulic motor to generate electrical power. This hydraulic system runs under two main disturbances, wind speed fluctuations and load variations. Intermittent nature of the wind applies a fluctuating torque on the hydraulic pump shaft. Also, variations of the consumed electrical power by the grid cause a considerable load disturbance on the system. This thesis studies the hydraulic wind power transfer systems. To get a better understanding, a mathematical model of the system is developed and studied utilizing the governing equations for every single hydraulic component in the system. The mathematical model embodies nonlinearities which are inherited from the hydraulic components such as check valves, proportional valves, pressure relief valves, etc. An experimental prototype of the hydraulic wind power transfer systems is designed and implemented to study the dynamic behavior and operation of the system. The provided nonlinear mathematical model is then validated by experimental result from the prototype. Moreover, this thesis develops a control system for the hydraulic wind power transfer systems. To maintain a fixed frequency electrical voltage by the system, the generator should remain at a constant rotational speed. The fluctuating wind speed from the upstream, and the load variations from the downstream apply considerable disturbances on the system. A controller is designed and implemented to regulate the flow in the proportional valve and as a consequence the generator maintains its constant speed compensating for load and wind turbine disturbances. The control system is applied to the mathematical model as well as the experimental prototype by utilizing MATLAB/Simulink and dSPACE 1104 fast prototyping hardware and the results are compared.
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Tungadio, Diambomba Hyacinthe-St. "Application of artificial intelligence algorithms in solving power system state estimation problem." 2013. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001381.
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M. Tech. Electrical Engineering.Discusses the practical management of electrical networks, no perfect monitoring of an electrical power system state is available, either because it is expensive or technically unfeasible due to the poor quality of the available measurements in the control centre. To have a stable network, the control centre must receive the network information to be able to provide a proper security in unforeseen situation. As a power system network is a complex and a non-linear system, it is important to use more advanced methods for its analysis and control in a real time environment. The aim of this research work is therefore, to apply several state estimation algorithms using artificial intelligence by developing their mathematical models for the purpose of comparing their performances in estimating the state variable of the power system. The three types of state estimation algorithms investigated for this research work are: the Particle Swarm Optimisation (PSO), the Genetic Algorithm (GA) and the Newton method for state estimation (NSE).
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Hamzehlouia, Sina. "MODELING AND CONTROL OF HYDRAULIC WIND ENERGY TRANSFERS." 2012. http://hdl.handle.net/1805/3365.
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Indiana University-Purdue University Indianapolis (IUPUI)The harvested energy of wind can be transferred to the generators either through a gearbox or through an intermediate medium such as hydraulic fluids. In this method, high-pressure hydraulic fluids are utilized to collect the energy of single or multiple wind turbines and transfer it to a central generation unit. In this unit, the mechanical energy of the hydraulic fluid is transformed into electric energy. The prime mover of hydraulic energy transfer unit, the wind turbine, experiences the intermittent characteristics of wind. This energy variation imposes fluctuations on generator outputs and drifts their angular velocity from desired frequencies. Nonlinearities exist in hydraulic wind power transfer and are originated from discrete elements such as check valves, proportional and directional valves, and leakage factors of hydraulic pumps and motors. A thorough understanding of hydraulic wind energy transfer system requires mathematical expression of the system. This can also be used to analyze, design, and predict the behavior of large-scale hydraulic-interconnected wind power plants. This thesis introduces the mathematical modeling and controls of the hydraulic wind energy transfer system. The obtained models of hydraulic energy transfer system are experimentally validated with the results from a prototype. This research is classified into three categories. 1) A complete mathematical model of the hydraulic energy transfer system is illustrated in both ordinary differential equations and state-space representation. 2) An experimental prototype of the energy transfer system is built and used to study the behavior of the system in different operating configurations, and 3) Controllers are designed to address the problems associated with the wind speed fluctuation and reference angular velocity tracking. The mathematical models of hydraulic energy transfer system are also validated with the simulation results from a SimHydraulics Toolbox of MATLAB/Simulink®. The models are also compared with the experimental data from the system prototype. The models provided in this thesis do consider the improved assessment of the hydraulic system operation and efficiency analysis for industrial level wind power application.
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Wu, Meng. "Fuzzy-Rule-Based Failure Detection and Early Warning System for Lithium-ion Battery." 2013. http://hdl.handle.net/1805/3522.
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Indiana University-Purdue University Indianapolis (IUPUI)Lithium-ion battery is one kind of rechargeable battery, and also renewable, sustainable and portable. With the merits of high density, slow loss of charge when spare and no memory effect, lithium-ion battery is widely used in portable electronics and hybrid vehicles. Apart from its advantages, safety is a major concern for Lithium-ion batteries due to devastating incidents with laptop and cell phone batteries. Overcharge and over-discharge are two of the most common electrical abuses a lithium-ion battery suffers. In this thesis, a fuzzy-rule-based system is proposed to detect the over-charge and over-discharge failure in early time. The preliminary results for the failure signatures of overcharged and over-discharged lithium-ion are listed based on the experimental results under both room temperature and high temperature. A fuzzy-rule-based model utilizing these failure signatures is developed and validated. For over-charge case, the abnormal increase of the surface temperature and decrease of the voltage are captured. While for over discharge case, unusual temperature increase during overcharge phases and abnormal current decrease during overcharge phases are obtained. The inference engine for fuzzy-rule-based system is designed based on these failure signatures. An early warning signal will be given by this algorithm before the failure occurs. This failure detection and early warning system is verified to be effective through experimental validation. In the validation test, the proposed methods are successfully implemented in a real-time system for failure detection and early warning. The result of validation is compatible with the design expectation. Finally an accurate failure detection and early warning system is built and tested successfully.
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Konda, Srikanth Reddy. "Resource scheduling in modern power system." Thesis, 2018. http://localhost:8080/xmlui/handle/12345678/7721.
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Vedam, Rajkumar. "Nonlinear control applied to power systems." Thesis, 1994. http://hdl.handle.net/1957/35510.
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When large disturbances occur in interconnected power systems, there exists the danger
that the power system states may leave an associated region of stability, if timely corrective action
is not taken. Open-loop remedial control actions such as field-forcing, line-tripping, switching of
series-capacitors, energizing braking resistors, etc., are helpful in reducing the effects of the
disturbance, but do not guarantee that the post-fault power system will be stabilized. Linear
controllers are widely used in the power industry, and provide excellent damping when the power
system state is close to the equilibrium. In general, they provide conservative regions of stability.
This study focuses on the development of nonlinear controllers to enhance the stability of
interconnected power systems following large disturbances, and allow stable operation at high
power levels.
There is currently interest in the power industry in using thyristor-controlled series-capacitors
for the dual purpose of exercising tighter control on steady-state power flows and
enhancing system stability. This device is used to implement the nonlinear controller in this
dissertation. A mathematical model of the power system controlled by the thyristor-controlled
series-capacitor is developed for the purpose of controller design.
Discrete-time, nonlinear predictive controllers are derived by minimizing criterion
functions that are quadratic in the output variables over a finite-horizon of interest, with respect to
the control variables. The control policies developed in this manner are centralized in nature. The
stabilizing effect of such controllers is discussed. A potential drawback is the need to have large
prediction horizons to assure stability. In this context, a coordinated-control policy is proposed, in
which the nonlinear predictive controller is designed with a small prediction horizon. For a class of
disturbances, such nonlinear predictive controllers return the power system state to a small
neighborhood of the post-fault equilibrium, where linear controllers provide asymptotic
stabilization and rapid damping. Methods of coordinating the controllers are discussed. Simulation
results are provided on a sample four-machine power system model.
There exists considerable uncertainty in power system models due to constantly shifting
loads and generations, line-switching following disturbances, etc. The performance of fixed-parameter
controllers may not be good when the plant description changes considerably from the
reference. In this context, a bilinear model-based self-tuning controller is proposed for the
stabilization of power systems for a class of faults. A class of generic predictive controllers are
presented for use with the self-tuning controller. Simulation results on single-machine and
multimachine power systems are provided.Graduation date: 1995
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Panigrahi, Bibhu Prasad, and Abhijit Pradhan. "Modern methods for power system harmonics estimation." Thesis, 2011. http://ethesis.nitrkl.ac.in/2499/1/e-Thesis.pdf.
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Harmonics has been present for a long time and its presence shapes the performance of a power system. Therefore, estimation of harmonics is of paramount importance while analyzing a power system network. Following the inception of harmonics, various filters have been devised to achieve an optimal control strategy for harmonic alleviation. This thesis introduces various algorithms to analyze harmonics in the power system. The objective is to estimate the power system voltage magnitude in the presence distortions taking into account the noise by employing different estimation approaches. We have focused our attention towards the study of Least Mean Squares (LMS) based filter, Recursive Least squares (RLS) based filter, Kalman filter (KF) and Extended Kalman (EKF) filter. For a test signal LMS, RLS, KF and EKF based algorithms have been analyzed and results have been compared. The proposed estimation approaches are tested for only static signals.