Dissertations / Theses on the topic 'Flexible distributions'
To see the other types of publications on this topic, follow the link: Flexible distributions.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Flexible distributions.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Haynes, Michele Ann. "Flexible distributions and statistical models in ranking and selection procedures with applications." Thesis, Queensland University of Technology, 1998.
Find full text
2
Carlsson, Daniel, and Johan Dvärsäter. "Flexibel Fysisk Distribution." Thesis, Linköping University, Department of Management and Economics, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-857.
Full textAbstract:
Bakgrund: Vi anser att en framtida utmaning är att bygga in en flexibilitet i den fysiska distributionen. Detta innebär att ett detaljhandelsföretag skall ha möjlighet att växla mellan att stundtals distribuera en och samma produkt via centrallager och stundtals direkt från producent till varuhus i förädlingskedjan, en flexibel fysisk distribution.
Syfte: Syftet är att utröna förutsättningar för och konsekvenser av en flexibel fysisk distribution för de olika aktörerna i en förädlingskedja, i vilken detaljhandelsföretaget besitter en påtaglig maktposition.
Genomförande: Empirisk data har samlats in genom en fallstudie i IKEA:s förädlingskedja.
Resultat: En integrerad förädlingskedja med ett tydligt supply chain synsätt, i vilken samtliga aktörer samarbetar och har incitament till medverkan, utgör en förutsättning för en flexibel fysisk distribution. Vi vill även framhålla vikten av att de produkter i ett detaljhandelsföretags sortiment som säljer bäst och endast de varuhus med störst kapacitet, bör ingå. Om den fysiska distributionen skall kunna växla i en förädlingskedja måste berörda aktörer vidare erhålla en planeringshorisont. Detta implicerar att skiften avseende fysisk distribution måste ske säsongsvis och då företrädesvis med direktleveranser i högsäsong. Den flexibla fysiska distributionen kommer att få konsekvenser gällande lager och därmed kostnader för aktörerna.
3
Tsegaye, Seneshaw Amare. "Flexible Urban Water Distribution Systems." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4597.
Full textAbstract:
With increasing global change pressures such as urbanization and climate change, cities of the future will experience difficulties in efficiently managing scarcer and less reliable water resources. However, projections of future global change pressures are plagued with uncertainties. This increases the difficulty in developing urban water systems that are adaptable to future uncertainty.
A major component of an urban water system is the distribution system, which constitutes approximately 80-85% of the total cost of the water supply system (Swamee and Sharma, 2008). Traditionally, water distribution systems (WDS) are designed using deterministic assumptions of main model input variables such as water availability and water demand. However, these deterministic assumptions are no longer valid due to the inherent uncertainties associated with them. Hence, a new design approach is required, one that recognizes these inherent uncertainties and develops more adaptable and flexible systems capable of using their active capacity to act or respond to future alterations in a timely, performance-efficient, and cost-effective manner.
This study develops a framework for the design of flexible WDS that are adaptable to new, different, or changing requirements. The framework consists of two main parts.
The first part consists of several components that are important in the pre and post--processing of the least-cost design methodology of a flexible WDS. These components include: the description of uncertainties affecting WDS design, identification of potential flexibility options for WDS, generation of flexibility through optimization, and a method for assessing of flexibility. For assessment a suite of performance metrics is developed that reflect the degree of flexibility of a distribution system. These metrics focus on the capability of the WDS to respond and react to future changes. The uncertainties description focuses on the spatial and temporal variation of future demand.
The second part consists of two optimization models for the design of centralized and decentralized WDS respectively. The first model generates flexible, staged development plans for the incremental growth of a centralized WDS. The second model supports the development of clustered/decentralized WDS. It is argued that these clustered systems promote flexibility as they provide internal degrees of freedom, allowing many different combinations of distribution systems to be considered. For both models a unique genetic algorithm based flexibility optimization (GAFO) model was developed that maximizes the flexibility of a WDS at the least cost.
The efficacy of the developed framework and tools are demonstrated through two case study applications on real networks in Uganda. The first application looks at the design of a centralized WDS in Mbale, a small town in Eastern Uganda. Results from this application indicate that the flexibility framework is able to generate a more flexible design of the centralized system that is 4% - 50% less expensive than a conventionally designed system when compared against several future scenarios. In addition, this application highlights that the flexible design has a lower regret under different scenarios when compared to the conventionally designed system (a difference of 11.2m3/US$). The second application analyzes the design of a decentralized network in the town of Aura, a small town in Northern Uganda. A comparison of a decentralized system to a centralized system is performed, and the results indicate that the decentralized system is 24% - 34% less expensive and that these cost savings are associated with the ability of the decentralized system to be staged in a way that traces the urban growth trajectory more closely. The decentralized clustered WDS also has a lower regret (a difference of 17.7m3/US$) associated with the potential future conditions in comparison with the conventionally centralized system and hence is more flexible.
4
Huang, Danguang. "Flexible design of urban water distribution systems." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/2948/.
Full textAbstract:
Urban water distribution systems (UWDS) are highly inter-connected and under many uncertainties from water demand, pipe roughness, and component failure. Accurate projections of these uncertainties are almost impossible, and thus it may not be a proper method to design the system to meet its performance criteria for the forecasted scenario. The system is designed for the deterministic not for the uncertainties, as a result it may not be efficient or effective to be operated under different future scenarios. Flexible design is shown as a useful strategy to cost-effectively respond to uncertainties because of its consideration of uncertainties in advance, and has been successfully applied in many engineering systems. The objective of flexible design is to identify flexibility sources in UWDS and embed them into the system design to respond to uncertainties. The thesis discussed different terms to define the property of the system to respond to uncertainties and proposed a definition of flexibility for UWDS. It then proposed different measures to indicate flexibility value and introduced an efficient method to handle numerous uncertain parameters in the model. It also develops an efficient method to identify high value flexibility sources based on the Flexibility Index. Finally the thesis presents a flexibility-based optimisation model that enable water engineers to compare different flexible design alternatives and generate optimal solutions. A definition of flexibility in UWDS is proposed to illustrate broadly its property to respond to uncertainties, since it is not so useful, or at least in this thesis to distinguish similar terms to define the property of the system to respond to uncertainties. Identified flexibility sources by the proposed method is not useful for the flexibility-based optimization model to design a system, but it might be a powerful tool to locate the weak points in the system or provide better update options during rehabilitation of the system. The computational efficiency of the proposed flexibility-based optimisation model was demonstrated by dramatic decreasing on the number of the required hydraulic simulation in the case study. Flexible designs in the case study are more expensive than inflexible design, but have better hydraulic performance under uncertainties.
5
Nock, Richard William Raymond. "Flexible precision timing instrumentation and quantum key distribution." Thesis, University of Bristol, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.658313.
Full textAbstract:
Time to Digital Conversion (TDC) is a fundamental building block of many applications, such as quantum information experiments, quantum key distribution, laser detection and ranging (LiDAR), bio-medical imaging, digital phase lock loops, and more. As of today, most timing instruments make use of analogue circuitry or application specific integrated circuits to time input events to picosecond resolution and bin size. As such solutions require programmable logic , to perform calibration and communication tasks, there would be a considerable cost and simplification gain obtained in implementing picosecond timing on the same programmable logic Integrated Circuit (IC). In addition to this, fully digital implementation would allow for such technology to enter broader markets. Numerous methods of implementing TDCs in programmable logic already exist. However, they are limited in bin size, linearity, accuracy or exhibit signi- . ficantly long dead times, due to the fixed structure of the Field Programmable Gate Array (FPGA) itself. This work demonstrates a novel ti~ing technique implemented within a low cost off the shelf FPGA that outperforms previously documented techniques in terms of bin size and linearity. A bin size of 1 ps, single shot precision of 17.11 ps , and a differential and integral. non linearity of < 1 has been demonstrated on a Spartan 6 LX75. The technique's performance is comparable to commercially available instruments costing in excess of an order of magnitude more. A flexible firmware and software defined timing platform has been developed, and four instruments have been demonstrated on it. A multi channel ('"'-'30 ps bin size) TDC, Time Correlated Single Photon Counter, coincidence counter and the aforementioned small bin size TDC have all been developed on a common low cost platform, exploiting the re-programmability of FPGAs. This allows for the functionality to be customised and changed at will, even remotely, as functionality is defined by the FPGA's bitfile and associated Personal Computer (PC) software. The use of such instruments is demonstrated, including hardware for two quantum key distribution systems (the Bristol free space system and the reference frame independent demonstration system), a LiDAR system, and in coincidence counting in quantum optics experiments.
6
Zhang, Irene Y. (Irene Yun). "Efficient file distribution in a flexible,wide-area file system." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/53188.
Full textAbstract:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 63-65).
WheelFS is a wide-area distributed file system designed to help applications cope with the challenges of sharing data over the wide-area network. A wide range of applications can use WheelFS as a storage layer because applications can control various trade-offs in WheelFS, such as consistency versus availability, using semantic cues. One key feature that many applications require from any storage system is efficient file distribution. The storage system needs to be able to serve files quickly, even large or popular ones, and allow users and applications to quickly browse files. Wide-area links with high latency and low throughput make achieving these goals difficult for most distributed storage systems. This thesis explores using pre fetching, a traditional file system optimization technique, in wide-area file systems for more efficient file distribution. This thesis focuses on Tread, a pref etcher for WheelFS. Tread includes several types of pre fetching to improve the performance of reading files and directories in WheelFS: read-ahead pre fetching, whole file prefetching, directory prefetching and a prefetching optimization for WheelFS's built-in cooperative caching. To makes the best use of scarce wide-area resources, Tread adaptively rate-limits prefetching and gives applications control over what and how prefetching is done using WheelFS's semantic cues. Experiments show that Tread can reduce the time to read a 10MB file in WheelFS by 40% and the time to list a directory with 100 entries by more than 80%.
(cont.) In addition, experiments on Planetlab show that using prefetching with cooperative caching to distribute a 10MB file to 270 clients reduces the average latency for each client to read the file by almost 45%.
by Irene Y. Zhang.
M.Eng.
7
Lynch, Alastair M. "Low Cost and Flexible Electronics for Quantum Key Distribution and Quantum Information." Thesis, University of Bristol, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520592.
Full text
8
He, Yujun. "Contribution au réglage de la tension sur un réseau HTA avec producteurs. Apport de la flexibilité de la demande." Thesis, CentraleSupélec, 2015. http://www.theses.fr/2015SUPL0005/document.
Full textAbstract:
L’intégration des producteurs décentralisés (DG) dans un réseau de distribution peut modifier le profil de tension et influencer le réglage de tension conventionnel. Pour le bon fonctionnement du réseau, le raccordement des DG ainsi que les charges grosses sont limités par le dimensionnement du réseau. Les travaux de cette thèse ont pour but de proposer une approche du réglage de tension dans un réseau de distribution avec producteur, en appuyant sur la flexibilité de la demande. Les moyens de réglage de tension seront constitués du régleur en charge (OLTC), la régulation de DG ainsi que la demande flexible. Une optimisation centralisée de type MINLP est proposée pour coordonner ces moyens de réglage. Il est montré que si les moyens de l’OLTC et de la puissance réactive ne suffissent pas de lever la contrainte de tension, il faut réduire la puissance active de producteur. Pour le gain de producteur, la demande flexible peut être considérée comme une source active. La modulation de « demand response » (DR) utilisant les charges thermiques est alors proposée au réglage de tension. L’effet de rebond est pris en compte pour les charges thermiques afin de ne pas affecter le profil de tension après l’action de DR. Ces travaux permettent d’envisager un réglage de tension plus active dans le réseau intelligent et augmenter la flexibilité du réseauGrowth of distributed generations (DG) in actual distribution networks will bring voltage issues that cannot be fixed by conventional voltage control means. For the sake of network safety, the size of DG and load in a distribution network is limited by the network parameters. The research described in this thesis aims to propose a voltage control strategy on distribution networks using the flexibility of demand. The voltage control means will consist of the on load tap changer (OLTC), the regulation of DG, and flexible demand. A centralized optimization of MINLP type is proposed to coordinate these voltage control means. It shows if it is not able to remove the voltage constraint with OLTC and reactive power regulation, then it must reduce the active power of DG. In order not to reduce active power of DG, the flexible demand is considered as an active source to take part in voltage control. The demand response (DR) modulation using thermal loads is thus proposed for voltage control. For the thermal load, the cold load pick-up (CLPU) effect must be taken into account in order not to affect the voltage profile after DR action. This work allows us to consider a voltage control strategy more active in smart distribution network and improve the flexibility of network
9
Bin-Ibrahim, Ahmad Asrul. "Operational planning and optimisation in active distribution systems for flexible and resilient power." Thesis, Durham University, 2018. http://etheses.dur.ac.uk/12872/.
Full textAbstract:
The electricity network is undergoing significant changes to cater to environmental-deterioration and fuel-depletion issues. Consequently, an increasing number of renewable resources in the form of distributed generation (DG) are being integrated into medium-voltage distribution networks. The DG integration has created several technical and economic challenges for distribution network operators. The main challenge is basically the problem of managing network voltage profile and congestion which is caused by increasing demand and intermittent DG operations. The result of all of these changes is a paradigm shift in the way distribution networks operate (from passive to active) and are managed that is not limited only to the distribution network operator but actively engages with network users such as demand aggregators, DG owners, and transmission-system operators. This thesis expands knowledge on the active distribution system in three specific areas and attempts to fill the gaps in existing approaches. A comprehensive active network management framework in active distribution systems is developed to allow studies on (i) the flexibility of network topology using modern power flow controllers, (ii) the benefits of centralised thermal electricity storage in achieving the required levels of flexibility and resiliency in an active distribution system, and (iii) system resiliency toward fault occurrence in hybrid AC/DC distribution systems. These works are implemented within the Advanced Interactive Multidimensional Modelling Systems (AIMMS) software to carry out optimisation procedure. Results demonstrate the benefit provided by a range of active distribution system solutions and can guide future distribution-system operators in making practical decisions to operate active distribution systems in cost-effective ways.
10
Haj-ahmed, Mohammed A. "Protection and Automation of Microgrids for Flexible Distribution of Energy and Storage Resources." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1430694499.
Full text
11
Touré, Sellé. "Optimisation des réseaux : réseau actif et flexible." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENT095/document.
Full textAbstract:
Le Système Électrique est soumis ces dernières années à plusieurs évolutions, depuis la dérégulationdu marché d'énergie à l'intégration de plus en plus importante de Générateurs Dispersés (GED). Ainsi,dans le cadre du concept de Smart Grid, les nouvelles technologies de l'information et de lacommunication (NTIC) offrent de nouvelles perspectives pour la gestion et l'exploitation des réseauxde distribution.Dans ce contexte, de nouveaux outils sont étudiés. Encore appelés Fonctions Avancéesd’Automatisation (FAA), le but principal de ces outils est d’utiliser tous les composants du réseau dedistribution de manière coordonnée en vue de les rendre plus actifs, flexibles et d’augmenter leurefficacité opérationnelle. Dans notre cas, nous avons étudié les fonctions associées à la reconfigurationen régime normal, du réglage de la tension et l’hybridation de ces deux derniers, tout en tenant comptede la présence des GED. En partant du comportement physique inhérent aux composants du réseau,plusieurs modèles ont été proposés. Certains sont tirés de la théorie des graphes et d’autres sur l’outilpuissant de la reformulation mathématique pour « convexifier » nos modèles. Cette modélisationadoptée répond à la fois à la nécessité de prendre en compte tous les moyens de réglages qui peuventêtre discrets (prises des transformateurs avec régleurs en charge ou des gradins de condensateurs),binaires (état de connectivité des composants) et continues (puissance réactive de la DG) et par lechoix des outils et des algorithmes d'optimisation mixte. En effet, la complexité de ces problèmes sonttelles que nous avons exploré à la fois des algorithmes méta-heuristiques (ACF : Algorithme desColonies de Fourmis) que déterministes (Décomposition de Benders Généralisée, Algorithme duBranch and Cut)The Electric Power System is undergoing a lot of evolutions in recent years, including the energymarket deregulation and the increasing integration of Dispersed Generators (DG). Therefore, withinthe framework of Smart Grid concept, the New Information and Communication Technologies (NICT)provide new perspectives to manage and operate distribution networks.In this context, new tools, called Advanced Distribution Automation functions (ADA, are beingstudied). The main objective of these tools is to use all the distribution network components in acoordinated manner to make them more active and flexible, in addition to increasing their operationalefficiency. In our case, we studied the functions associated with the reconfiguration problem, thevoltage control problem and the hybridization of these two, while taking into account the presence ofthe DG. Based on the inherent components of network physical models, several models have beenproposed. Some are derived from the graph theory and others use powerful mathematicalreformulation to make our models convex. The adopted models answer to the necessity of taking intoaccount all regulation means, which can be discrete (On Load Tap-Changer and capacitor banks),binary (components connectivity such as lines or transformers) and continuous (DG reactive power ),and by the choice of tools and algorithms of mixed optimization. Indeed, the complexity of theseproblems is such that we have explored both algorithms: meta-heuristic (ACA, Ant Colony Algorithm)and deterministic (Generalized Benders Decomposition, Branch and Cut Algorithm)
12
CHEN, JUNLIANG. "A MONTE CARLO EM ALGORITHM FOR GENERALIZED LINEAR MIXED MODELS WITH FLEXIBLE RANDOMEFFECTS DISTRIBUTION." NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20011025-112332.
Full textAbstract:
CHEN, JUNLIANG. A Monte Carlo EM algorithm for generalized linear mixed modelswith flexible random effects distribution. (Under the direction of DaowenZhang and Marie Davidian)A popular way to model correlated binary, count, or other data arising inclinical trials and epidemiological studies of cancer and other diseases is byusing generalized linear mixed models (GLMMs), which acknowledge correlationthrough incorporation of random effects. A standard model assumption is thatthe random effects follow a parametric family such as the normal distribution.However, this may be unrealistic or too restrictive to represent the data,raising concern over the validity of inferences both on fixed and randomeffects if it is violated.Here we use the seminonparametric (SNP) approach (Davidian and Gallant 1992,1993) to model the random effects, which relaxes the normality assumption andjust requires that the distribution of random effects belong to a class of``smooth'' densities given by Gallant and Nychka (1987). This representation allows the density of random effects to be very flexible, including densitiesthat are skewed, multi--modal, fat-- or thin--tailed relative to the normal, andthe normal as a special case. We also provide a reparameterization of thisrepresentation to avoid numerical instability in estimating the polynomialcoefficients.Because an efficient algorithm to sample from a SNP density is available, wepropose a Monte Carlo expectation maximization (MCEM) algorithm using arejection sampling scheme (Booth and Hobert, 1999) to estimate the fixedparameters of the linear predictor, variance components and the SNP density. Astrategy of choosing the degree of flexibility required for the SNP density isalso proposed. We illustrate the methods by application to two data sets fromthe Framingham and Six Cities Studies, and present simulations demonstratingperformance of the approach.
13
Soroudi, Alireza. "Architecture des réseaux de distribution en présence de production décentralisée. Planification sous incertitudes et modes d'exploitation décentralisés." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00738033.
Full textAbstract:
La libéralisation du marché de l'électricité a introduit plusieurs nouveaux sujets de recherche intéressants dans la zone du système électrique. Cette thèse aborde l'un des problèmes fascinants parmi eux: l'étude de la génération distribuée à la fois renouvelable et classique d'intégration dans les réseaux de distribution. De Gestionnaires de Réseau de Distribution (GRD) point de vue, il est intéressant de développer une méthodologie globale qui considère les différentes technologies de production décentralisée (GD) comme une option pour la fourniture à la demande. Dans cette thèse, le problème de planification a été modélisé avec la méthodologie de multi-objectif. Cela aidera le planificateur de la prise de décision tout en sachant les arbitrages entre les fonctions objectives. Afin de trouver le front de Pareto optimale du problème, un hybride génétique-immunes algorithme est proposé. La méthode floue satisfaisant est utilisé pour trouver la solution finale. Divers objectifs comme le coût, les pertes actifs, d'émissions et de la satisfaction de contraintes techniques ont été prises en compte. Les variables de décision sont les stratégies de renforcement des réseaux de distribution et aussi les décisions d'investissement concernant les modules GD, dans le cas où GRD peut investir dans des modules de DG aussi. Un autre aspect qui rend les modèles proposés plus flexible, est compte tenu des incertitudes sur les paramètres d'entrée. Les incertitudes des données d'entrée ont été traitées de trois manières différentes à savoir : probabiliste, possibiliste et finalement mélangés possibiliste-probabilistes. Dans cette thèse, deux types de modèles ont été développés: centralisé et dégroupé modèle de planification GD. Dans les deux modèles, le GRD est responsable de fournir un réseau fiable et performant pour ses clients sur son territoire. Dans le contexte de planification centralisée, le GRD est autorisé à faire des investissements dans les modules de la GD. Dans ce modèle, la taille optimale, nombre d'unités de la GD, l'emplacement, la technologie et de la GD, calendrier des investissements dans les modules de GD à la fois et les composants du réseau sont déterminés. Le modèle développé ne sera pas seulement utile dans le contexte de la planification centralisée, mais est également applicable aux marchés de l'énergie d'autres qui ont besoin pour évaluer, surveiller et guider les décisions des développeurs GD. Dans le modèle de planification de la GD dégroupé, le GRD n'est pas autorisé à prendre des décisions d'investissement dans les options de la GD. Les variables de décision du GRD sont limités à renfort de réseau, le placement de condensateurs, la reconfiguration du réseau et des technologies de réseau intelligent.
14
Shi, Yunzhu. "Comparison of the stress distribution in the metallic layers of flexible pipes using two alternative Bflex formulations." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26070.
Full textAbstract:
Axisymmetric load is the most common load acting on flexible pipe. Modelling axisymmetric load correctly is very important to estimate the strength of a flexible pipe. The purpose of the thesis is to compare the stress distribution in metallic layers under three load case, i.e. tension, internal pressure and external pressure. Literature study and discussion to mechanical properties of flexible pipe and finite element modelling method are included in the thesis. The modelling program is BFLEX program. Models for three flexible pipes are built in BFLEX for 6inch pipe, 8inch pipe and 16inch pipe. Different element models are applied to model metallic layers. Element PIPE52 are used to model all metallic layers for ITCODE31 model. For ITCODE0 model, element PIPE52 are used to model carcass and pressure armour; element HSHEAR352 is used to model helical tensile layer. For full FE model, carcass and pressure armour are modelled by element HSHEAR363 and tensile layer is modelled by element HSHEAR353. For ITCODE31 and ITCODE0 models, the computing stress is taken from local model after BPOST. For full FE model, the stress is from global model directly. Moreover, analytical solution is found to estimate the modelling performance.
15
Norén, Andreas. "All-Digital Aggregator for Multi-Standard Video Distribution." Thesis, Linköpings universitet, Kommunikationssystem, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-149301.
Full textAbstract:
In video transmission there is a need to compose a wide-band signal from a numberof narrow-band sub-signals. A flexible solution offers the possibility to place any narrow-band sub-signal anywhere in the wide-band signal, making better use of the frequency space of the wide-band signal. A multi-standard supportive solution will also consider the three standard bandwidths of digital and analog video transmissions, both terrestrial and cable (6; 7 and 8 MHz), in use today. This thesis work will study the efficiency of a flexible aggregation solution, in terms of computational complexity and error vector magnitude (EVM). The solution uses oversampled complex modulated filter banks and inner channelizers, to reduce the total workload on the system. Each sub-signal is channelized through an analysis filter bank and together all channelized sub-signals are aggregated through one synthesis filter bank to form the wide-band composite signal. The EVM between transmitted and received sub-signals are investigated for an increasing number of sub-signals. The solution in this thesis work is performing good for the tested number of up to 100 narrow-band sub-signals. The result indicates that the multi-standard flexible aggregation solution is efficient for an increasing number of transmitted sub-signals.
16
Basupi, Innocent. "Adaptive water distribution system design under future uncertainty." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/14722.
Full textAbstract:
A water distribution system (WDS) design deals with achieving the desired network performance. WDS design can involve new and / or existing network redesigns in order to keep up with the required service performance. Very often, WDS design is expensive, which encourages cost effectiveness in the required investments. Moreover, WDS design is associated with adverse environmental implications such as greenhouse gas (GHG) emissions due to energy consumption. GHGs are associated with global warming and climate change. Climate change is generally understood to cause reduction in water available at the sources and increase water demand. Urbanization that takes into account factors such as demographics (population ageing, household occupancy rates, etc.) and other activities are associated with water demand changes. In addition to the aforementioned issues, the challenge of meeting the required hydraulic performance of WDSs is worsened by the uncertainties that are associated with WDS parameters (e.g., future water demand). With all the factors mentioned here, mitigation and adaptive measures are considered essential to improve WDS performance in the long-term planning horizon. In this thesis, different formulations of a WDS design methodologies aimed at mitigating or adapting the systems to the effects of future changes such as those of climate change and urbanization are explored. Cost effective WDS designs that mitigate climate change by reducing GHG emissions have been investigated. Also, water demand management (DM) intervention measures, i.e., domestic rainwater harvesting (RWH) systems and water saving appliance schemes (WSASs) have been incorporated in the design of WDSs in an attempt to mitigate, adapt to or counteract the likely effects of future climate change and urbanization. Furthermore, flexibility has been introduced in the long-term WDS design under future uncertainty. The flexible methodology is adaptable to uncertain WDS parameters (i.e., future water demand in this thesis) thereby improving the WDS economic cost and hydraulic performance (resilience). The methodology is also complimented by strategically incorporating DM measures to further enhance the WDS performance under water demand uncertainty. The new methodologies presented in this thesis were successfully tested on case studies. Finally, conclusions and recommendations for possible further research work are made. There are potential benefits (e.g., cost savings, additional resilience, and lower GHG emissions) of incorporating an environmental objective and DM interventions in WDS design. Flexibility and DM interventions add value in the design of WDSs under uncertainty.
17
Lampe, Erik Joseph. "Measuring impact of CONWIP control on production rate and inventory distribution for a flexible production system through simulation." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40459.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (leaf 30).
This research investigates the production output and inventory distribution of a manufacturing system that produces multiple part types on flexible machines while incorporating CONWIP inventory controls. The production machines, which are separated by individual storage areas for each part type, are modeled as unreliable and operate according to a strict priority sequence. The maximum total inventory of each part type in the entire system is limited a preset number of tokens in the system. While varying the token levels and the demand for finished parts, the average production output for each part type and the average inventory level for each buffer is monitored to understand their behaviors. The relationship between the inventory distributions and the production rates is also investigated. The goal of this research is to develop intuition behind the system behavior.
by Erik Joseph Lampe.
S.B.
18
Guo, Yue. "Capability assessment of VAr support and demand response to transmission network using flexible tap changing techniques in distribution networks." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/capability-assessment-of-var-support-and-demand-response-to-transmission-network-using-flexible-tap-changing-techniques-in-distribution-networks(5a373163-d2c9-4e13-9720-0c4fa0456c3f).html.
Full textAbstract:
Due to the increasing integration of renewable energy generations, the overvoltage and overload issues in transmission networks have become more significant, and they may occur at various locations. To mitigate the overvoltage issues, traditional solutions which often consider the installation of reactive power compensators such as shunt reactors, SVC, STATCOM may not be cost-effective. To mitigate the overload issues, traditional methods using direct or price-based demand control will affect customersâ electrical experience in that they are inconvenienced greatly. This thesis discusses the flexible tap changing techniques that utilise existing parallel transformers in distribution networks to provide reactive power absorption and demand response services for transmission systems. Among them, the tap stagger technique operates parallel transformers in small different tap positions, i.e. staggered taps, to result in more reactive power absorption from upstream networks. In addition, the tap changing technique changes voltages in the range of statutory limits through the adjustment of tap positions in order to change network demands without directly affecting customers. The aggregated reactive power absorption or demand response from many pairs of parallel transformers in distribution networks could be sufficient to provide VAr or demand support to transmission networks. Network capability studies have been carried out in OpenDSS simulation software to investigate the VAr absorption capability by using tap staggering technique and the demand reduction capability by using tap changing technique. The studies are based on two UK HV distribution networks (132-33kV) with 11 and 28 primary substations (33/11 or 6.6 kV) respectively, and the techniques are applied to parallel transformers in primary substations. Based on the results of the two networks, the capabilities of the whole ENW and the UK distribution networks have been estimated respectively by using linear estimation method. In addition, the VAr absorption capability of the tap stagger technique has been validated by using site trial data. The results show an average VAr absorption capability of 0.89MVAr for a primary substation, 315MVAr for ENW networks and about 2500MVAr for the UK at stagger level 4 and show an average demand reduction capability of 3.1% of the original demand at tap down level 3. The results of capability studies together with the validations results confirm that the flexible tap changing techniques are able to provide transmission networks with effective VAr support and demand response services. To assess network VAr absorption and demand response capability more precisely, this thesis also proposes an online load profile estimation method to estimate the load profiles of the network more accurately if not all substations in the network are monitored. The method uses Peak Load Share values, Euclidean Distance, and some load measurements to estimate load profiles. The method has been validated and compared with a traditional aggregation-based method. The results show an average estimation error of 13% ~ 23% in different conditions using the proposed method, and show an average estimation error reduction from about 47% (using the traditional method) to about 13% (using the proposed method). The results indicate that the developed method has a considerable improvement on the accuracy of load profile estimation.
19
Parat, Elisabeth. "Les stratégies de flexibilité adoptées par les protagonistes d'un secteur en crise : le cas de la flière Textile-Habillement-Distribution française." Paris 13, 1997. http://www.theses.fr/1997PA131030.
Full textAbstract:
Cette recherche, dans un premier temps, presente la flexibilite sous un aspect theorique. La flexibilite de la production, des techniques et du travail ont ete etudiees. Apres avoir mis en exergue ces trois types de flexibilite, nous nous sommes efforces d'analyser les strategies en terme de flexibilites adoptees par les protagonistes d'un secteur en crise. Notre choix s'est porte sur les secteurs textile - habillement francais. Dans le souci de determiner le cadre de cette analyse, nous avons presente, les principaux elements qui ont contribue a affecter l'organisation traditionnelle de la filiere textile - habillement, a la fois en france et dans les principaux pays europeens specialises (allemagne, grande-bretagne, italie). Ainsi, apres avoir expose le cadre de fonctionnement des activites textile et habillement, une partie empirique, illustree par plusieurs enquetes de terrain presente les strategies de flexibilite adoptees par les differents protagonistes du marche francais de l'habillement (les acteurs traditionnels que sont les fabricants, les nouveaux acteurs du marche : les distributeurs et enfin, les intermediaires, faconniers, importateurs et le sentier parisien). Il ressort de ce travail que l'entree massive de nouveaux acteurs distributeurs (que nous avons distingue en deux categories : les distributeurs + actifs ; et les + neo-specialistes ;) des le debut de la decennie 80, est venue bouleverser radicalement les regles de fonctionnement de ce secteur d'activite et les strategies des entreprises traditionnelles. . .
20
Nguyen, Theanh. "SHM through flexible vibration sensing technologies and robust safety evaluation paradigm." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/78632/5/Andy%20Nguyen%20Thesis.pdf.
Full textAbstract:
This research has successfully developed a novel synthetic structural health monitoring system model that is cost-effective and flexible in sensing and data acquisition; and robust in the structural safety evaluation aspect for the purpose of long-term and frequent monitoring of large-scale civil infrastructure during their service lives. Not only did it establish a real-world structural monitoring test-bed right at the heart of QUT Gardens Point Campus but it can also facilitate reliable and prompt protection for any built infrastructure system as well as the user community involved.
21
Richardson, Ian. "Integrated high-resolution modelling of domestic electricity demand and low voltage electricity distribution networks." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/7968.
Full textAbstract:
Assessing the impact of domestic low-carbon technologies on the electricity distribution network requires a detailed insight into the operation of networks and the power demands of consumers. When used on a wide-scale, low-carbon technologies, including domestic scale micro-generation, heat pumps, electric vehicles and flexible demand, will change the nature of domestic electricity use. In providing a basis for the quantification of the impact upon distribution networks, this thesis details the construction and use of a high-resolution integrated model that simulates both existing domestic electricity use and low voltage distribution networks. Electricity demand is modelled at the level of individual household appliances and is based upon surveyed occupant time-use data. This approach results in a simulation that exhibits realistic time-variant demand characteristics, in both individual dwellings, as well as, groups of dwellings together. Validation is performed against real domestic electricity use data, measured for this purpose, from dwellings in Loughborough in the East Midlands, UK. The low voltage distribution network is modelled using real network data, and the output of its simulation is validated against measured network voltages and power demands. The integrated model provides a highly detailed insight into the operation of networks at a one-minute resolution. This integrated model is the main output of this research, alongside published articles and a freely downloadable software implementation of the demand model.
22
Athanasiadis, Nikolaos P. "Modelling, control and design of Flexible AC Transmission Systems (FACTS), custom power devices and variable speed drives for transmission and distribution architectures." Thesis, University of Strathclyde, 1999. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21441.
Full textAbstract:
The main tasks of power electronics in power transmission and distribution systems is to process and control the flow of electric energy by supplying voltages and currents in a form that is suitable for user loads. In recent years, the field of power electronics has experienced a large growth. Electric utilities expected that by the year 2000 over half of the electrical load may be supplied through power electronic systems. In order to take advantage of this highly developed technology a number of detailed modelling procedures and simulation facilities are needed. The work in this thesis is concentrated on modelling, control and design of various power electronic based models for use within transmission and distribution systems. The overall objective is to provide effective methods and tools for assessing the impact of the latest technology based on power electronic devices in the reinforcement of power system networks. The thesis clarifies modelling and control of various variable speed drive models, such as the six-step, PWM and vector control and gives a detailed account of the systematic derivation of equations that are necessary for the dynamic and transient analysis of a multi-machine multi-node power system with associated adjustable speed drives. Simulation of Flexible AC Transmission Systems (FACTS) models has also been developed for a number of devices including: the SVC (Static Var Compensator), the STATCON (Static Condenser) and the UPFC (Unified Power Flow Controller). The methodologies for development of the models are described and a number of case studies are included in order to give a broad overview of the applications and to prove the usefulness of the results. The last part of the thesis includes simulation, control and design of Custom Power Devices for use within distribution system architectures. It starts with a complete control system strategy for the modelling of a solid-state switch and continues with the modelling of a Dynamic Voltage Restorer model, using an innovative control system. The creation of the power electronics models library provides several opportunities for future developments, which are discussed in the concluding sections of the thesis.
23
Smith, Johan. "High voltage direct current strategy solving power delivery shortages to localized area of national grid." Thesis, Cape Peninsula University of Technology, 2009. http://hdl.handle.net/20.500.11838/1102.
Full textAbstract:
Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2009The industrial and population growth of a nation can cause power delivery problems to localized areas of a national grid through their increased demand for electrical energy. One reason for these power shortages is the insufficient current carrying capacity of existing high voltage alternating current, (HVAC), transmission lines supplying the area. High voltage direct current (HVDC) transmission lines are a possible solution as they provide better power delivery than HVAC lines. New or upgraded HVAC lines, or HVDC lines or combinations of HVAC and HVDC lines are possible solutions to improve power delivery. This research investigates the various line possibilities using theory. and cutting edge frequency and time domain software tools. The challenge is how to approach this problem. What methodology or structure should be used? Thus one of the contributions of this work is the development of a strategy (flow chart), for solving power delivery problems to localized areas of a national grid through individual or combinations (e.g. parallel operation) of HVAC and/or HVDC transmission lines. The main contribution is the evaluation of a HVDC system as a solution to overcoming power delivery shortages to a localized area of a national grid. Three different software packages (two industrial and one academic) namely, PSCAD/EMTDC (time domain), DlgSILENT PowerFactory (frequency domain) and MathCAD software are evaluated for their capability to perform the simulation studies necessary to prove the possible solutions given in the developed flow chart. The PSCAD/EMTDC software package is evaluated for integrated HVAC/HVDC load flow analyses, DlgSILENT for individual and parallel combinations of HVAC lines and MathCAD to prove hand calculations to software results. Five case studies are conducted. The first case study demonstrates a healthy system with no delivery shortcomings, the second case study portrays the delivery shortcoming due to increased localized area demand, and the remaining three case studies explore possible solutions to solve the problem. The first possible solution is to construct an identical HVAC line in parallel to the existing line.
24
Essaadi, Imane. "Conception de réseaux de distribution pour une personnalisation produit : une contextualisation à l'échelle du continent Africain." Thesis, Paris 10, 2018. http://www.theses.fr/2018PA100182/document.
Full textAbstract:
Face à la forte concurrence internationale, de nombreuses entreprises manufacturières orientent leurs investissements vers les marchés africains pour accroître leur part de marché et rester compétitives sur le marché mondial. Ces marchés sont effet en plein essor mais demandent des produits de grande diversité. En dépit de cette attractivité, les flux commerciaux en Afrique demeurent faibles en raison de la faible qualité des infrastructures et de l’absence d’écosystèmes logistiques régionaux connectant les pays africains de manière fiable et efficace.C’est pourquoi cette thèse de doctorat s’intéresse à la modélisation et à la résolution du problème de conception de réseaux de distribution hybrides en Afrique, intégrant des plateformes de distribution et de personnalisation finale des produits. Ces réseaux incluent, en amont, des hubs régionaux servant de porte d’entrée vers les marchés d’une région continentale. Le report de la personnalisation finale en aval du réseau logistique permet de réduire les délais de livraison aux marchés et le coût de distribution tout en maintenant une économie d’échelle. La méthodologie que nous proposons repose sur deux grands axes de recherche :▪ Le premier axe vise à définir la localisation des hubs logistiques régionaux, sur la base d’une analyse multicritères floue, version améliorée de TOPSIS floue et d'AHP ;▪ Le deuxième axe aborde conception de réseaux de distribution hybrides servant des marchés fortement diversifiés (exemple : marchés des engrais). Nous avons proposé deux nouveaux modèles d'optimisation multi-objectifs minimisant le coût total d’exploitation et d’investissement, maximisant la proximité des produits aux marchés et minimisant les dommages sur les produits finis durant leur distribution. Le premier modèle est déterministe tandis que le deuxième propose une conception flexible alignée sur la dynamique et l’incertitude de l’évolution des marchés africainsIn the context of intense international competition, many manufacturing firms are directing their investments toward African markets to increase their market share and maintain their competitiveness in the global market. These markets are rapidly growing but require customized products. Despite their attractivity, trade flows in Africa remain low due to the poor quality of infrastructure and the lack of regional logistic ecosystems, connecting African countries through reliable and efficient services.This doctoral thesis therefore focuses on modelling and solving the problem of designing hybrid distribution networks in Africa, integrating distribution and final customization platforms. These networks incorporate, upstream, regional hubs that serve as gateways to regional markets. The postponement of final customization downstream of the logistics network reduces the delivery times and downstream distribution costs while maintaining upstream economies of scale.The methodology we suggest is based on two main areas of research:▪ The first axis aims to define the location of regional logistics hubs, based on a fuzzy multi-criteria analysis approach, which is an improved version of TOPSIS fuzzy and AHP;▪ The second axis focuses on the design of hybrid distribution networks serving highly diversified markets in Africa (for example: fertilizer markets). To this aim, we propose two new multi-objective optimization models minimizing total operating and investment costs, maximizing product proximity to markets and minimizing damage to finished products during their distribution. The first model is deterministic while the second one proposes a flexible design in response to the dynamics and uncertainty of the evolution of African markets
25
Shields, Jean-Philippe. "Élaboration du modèle conceptuel flexible et extensible d'une architecture logicielle orientée-objet permettant la parallélisation et la distribution d'une architecture de simulation séquentielle." Thesis, Université Laval, 2007. http://www.theses.ulaval.ca/2007/24474/24474.pdf.
Full text
26
Gouin, Victor. "Évaluation de l’impact du Smart Grid sur les pratiques de planification en cas d’insertion de production décentralisée et de charges flexibles." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT097/document.
Full textAbstract:
Les réseaux intelligents, ou Smart Grids, résultent de la combinaison des réseaux électriques et des nouvelles technologies de l'information et de la communication. Ils s'accompagnent de changements de paradigmes comme l'insertion importante de production décentralisée et le développement de nouveaux modes de consommation, comme les véhicules électriques et les « consom'acteurs ». Des contraintes apparaissent ainsi sur des réseaux vieillissants et non dimensionnés pour ces nouveaux usages. Cette thèse étudie l'impact des nouveaux paradigmes sur les techniques de planification des réseaux électriques de distribution. Un premier outil utilisant un algorithme de recuit simulé adapté et des méthodes issues de la théorie des graphes a été développé pour dimensionner les réseaux à moindre coût, selon les règles usuelles de planification. Dans un second temps, une méthodologie combinant une approche de type Monte Carlo et la construction de profils annuels de charge a été proposée pour analyser l'impact de la production décentralisée et des véhicules électriques dans un contexte soumis à des incertitudes. La troisième étape du travail a été de mettre en place des fonctions avancées de conduite comme alternative aux solutions de renforcement, très coûteuses. Un regard particulier est porté sur les stratégies d'effacement. Enfin, une nouvelle planification opérationnelle combinant les précédents outils développés a été créée afin d'évoluer vers une planification des réseaux intelligentsThe Smart Grids are the combination of electrical networks and new information and communication technologies. They deal with a change of paradigms that are the insertion of distributed generation and the development of new forms of consumption, such as electric vehicles and prosumers. These changes induce many constraints on networks both aging and historically not sized for this context. This thesis studies the impact of these paradigms on the rules for electrical distribution networks planning. A first tool using an adapted simulated annealing algorithm and methods from graph theory was developed to size the networks at low cost, according to the usual rules for planning. Secondly, a methodology combining a Monte Carlo approach and the construction of annual load profiles was proposed to analyze the impact of distributed generation and electric vehicles in an environment subject to uncertainties. The third stage of the work was to implement advanced distribution automations as an alternative to reinforcement, which is very expensive. This part is focused on demand side management. Finally, a new operational planning combining the previous developed tools was created to move towards the planning of the Smart Grids
27
Hofmann, John. "Extension of the Method of Ellipses to Determining the Orientation of Long, Semi-flexible Fibers in Model 2- and 3-dimensional Geometries." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/23921.
Full textAbstract:
The use of fiber-reinforced polymer composites formed via injection molding is of increasing interest due to their superior mechanical properties as compared to those of the polymer matrix alone. These mechanical properties, however, are strongly dependent on the fiber length and orientation distributions within a molded part. As such, there is a need to understand and model the orientation evolution of chopped fibers in flow in order to accurately simulate the final fiber orientation distribution within injection molded parts. As a result of this, accurate and reliable experimental measurement of fiber orientation is needed.
Within this research, the application and validity of the Method of Ellipses for determining the orientation of long, semi-flexible glass fibers within injection molded composites has been investigated. A fiber suspension with an average length of approximately 3.9 mm was the focus of this study and assumed to be representative of commercial distributions. A novel method to quantify fiber curvature was developed and utilized to show that flexibility in center-gated disc and the end-gated plaque samples was minimal on average for the selected fiber length distribution. Thus, it was determined that the Method of Ellipses was applicable when utilized to obtain reliable orientation data for the selected long glass fiber suspension and within the chosen geometries that exhibit 1-, 2-, and 3-dimensional velocity fields. However, a modified image analysis width was found to be necessary in regions of highly aligned fibers, due to the increase in ellipse size and the need to reduce the number of partial objects and thus minimize error. This allowed for a direct comparison of the experimental orientation behavior of short and long glass fibers within the center-gated disc and the end-gated plaque, as well as the effect of the orientation distributions on the global modulus of the part.Ph. D.
28
Monavon, Arnault. "Etude d'une couche limite instationnaire sur une paroi déformable." Paris 6, 1986. http://www.theses.fr/1986PA066369.
Full text
29
Ghias, Nezhad Omran Nima. "Power grid planning for vehicular demand: forecasting and decentralized control." IEEE Transactions on Smart Grid, 2014. http://hdl.handle.net/1993/23891.
Full textAbstract:
Temporal and spatial distribution of incoming vehicular charging demand is a significant challenge for the future planning of power systems. In this thesis the vehicular loading is-sue is categorized into two classes of stationary and mobile; they are then addressed in two phases.
The mobile vehicular load is investigated first; a location-based forecasting algorithm for the charging demand of plug-in electric vehicles at potential off-home charging stations is proposed and implemented for real-world case-studies. The result of this part of the re-search is essential to realize the scale of fortification required for a power grid to handle vehicular charging demand at public charging stations.
In the second phase of the thesis, a novel decentralized control strategy for scheduling vehicular charging demand at residential distribution networks is developed. The per-formance of the proposed algorithm is then evaluated on a sample test feeder employing real-world driving data. The proposed charging scheduling algorithm will significantly postpone the necessity for upgrading the assets of the network while effectively fulfilling customers’ transportation requirements and preferences.October 2014
30
Lessa, Avanir Carlos. "Estudo e modelagem de um DSTATCOM para aplicação em sistemas de distribuição com problemas de desequilíbrio de tensão." reponame:Repositório Institucional da UFABC, 2014.
Find full textAbstract:
Orientador: Prof. Dr. Claudionor Francisco do NascimentoDissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Elétrica, 2014.
Os sistemas de distribuição de energia elétrica, de um modo geral, são radiais. Estes sistemas podem possuir problemas de qualidade da energia elétrica em suas barras, tais como os desequilíbrios de tensão e de corrente. Ademais, as redes de distribuição podem conter uma grande quantidade de cargas monofásicas e trifásicas desequilibradas, indutivas e não lineares, o que pode resultar nos seguintes problemas: baixo fator de potência, desequilíbrio de tensão e distorção harmônica. Nesse sentido, devido à dinâmica destas cargas e a ocorrência de fenômenos, como afundamento de tensão por partidas de grandes motores e curtos-circuitos, há a necessidade de solução destas anormalidades, com respostas rápidas de estabilização. De maneira a atender a esta necessidade, os resultados das recentes pesquisas baseadas na eletrônica de potência têm proporcionado a utilização de equipamentos capazes de trabalhar em sistemas de potência de alta tensão. Esse avanço permite aplicações de dispositivos FACTS (Flexible Alternating Current Transmission Systems) nas operações de flexibilidade e mitigação de problemas comuns às redes de energia elétrica de transmissão e de distribuição, melhorando, assim, a qualidade da energia elétrica, o que aumenta a confiabilidade destes sistemas. Com este propósito, o presente trabalho tem como objetivo principal o estudo e a modelagem de um DSTATCOM (Distribution Static Compensator) em um sistema de distribuição de energia elétrica com variações de tensão, avaliando os possíveis benefícios proporcionados a este sistema. Os resultados de simulação foram obtidos com o auxílio do software MatLab/Simuling.
Distribution systems of electric power, in general, are radial. These systems have power quality problems in their power bars, such as the voltage variations. Moreover, the distribution networks contain a large amount of single-phase and three-phase unbalanced loads, inductive and non-linear, which may result in the following problems: low power factor, voltage unbalance, and harmonic distortion. Accordingly, due to the dynamic loads and the occurrence of these phenomena, such as voltage sag matches by large motors and short circuits, there is a need for solution of these abnormalities, with responsive stabilization. In order to meet this need, the results of recent research based on power electronics have provided the use of equipment to work on systems of high voltage power. This advancement allows applications FACTS devices (Flexible Alternating Current Transmission Systems) flexibility in operations and mitigation of problems common to the networks of electricity transmission and distribution, thus improving the quality of electric power, which increases the reliability of these systems. For this purpose, the present work has as main objective the study and modeling of a DSTATCOM (Distribution Static Compensator) in a system of electricity distribution, evaluating the possible benefits provided to the electric power system. The simulation results were obtained with the aid of software Matlab/Simuling. The effectiveness of the work has been proven since the DSTATCOM installed, the distribution network operated within established standards.
31
Klibi, Walid. "The Design of Effective and Robust Supply Chain Networks." Thesis, Université Laval, 2009. http://www.theses.ulaval.ca/2009/26790/26790.pdf.
Full text
32
Prueter, Phillip Edward. "A Study of the Mechanical Design and Gear Tooth Root Strains in Flexible Pin, Multi-Stage, Planetary Wind Turbine Gear Trains Using Three Dimensional Finite Element/Contact Mechanics Models and Experiments." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313372765.
Full text
33
Nguyen, Van Liem. "Modeling and control coordination of power systems with FACTS devices in steady-state operating mode." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0036.
Full textAbstract:
This thesis is devoted to the development of new models for a recently-implemented FACTS (flexible alternating current transmission system) device, the unified power flow controller (UPFC), and the control coordination of power systems with FACTS devices in steady-state operating mode. The key objectives of the research reported in the thesis are, through online control coordination based on the models of power systems having FACTS devices, those of maximising the network operational benefit and restoring system static security following a disturbance or contingency. Based on the novel concept of interpreting the updated voltage solutions at each iteration in the Newton-Raphson (NR) power-flow analysis as dynamic variables, the thesis first develops a procedure for representing the unified power flow controllers (UPFCs) in the steady-state evaluation. Both the shunt converter and series converter control systems of a UPFC are modeled in their dynamical form with the discrete time variable replaced by the NR iterative step in the power-flow analysis. The key advantage of the model developed is that of facilitating the process of UPFC constraint resolution during the NR solution sequence. Any relative priority in control functions pre-set in the UPFC controllers is automatically represented in the power-flow formulation. Although the developed UPFC model based on the dynamic simulation of series and shunt converter controllers is flexible and general, the number of NR iterations required for convergence can be large. Therefore, the model is suitable mainly for power system planning and design studies. For online control coordination, the thesis develops the second UPFC model based on nodal voltages. The model retains all of the flexibility and generality of the dynamic simulation-based approach while the number of iterations required for solution convergence is independent of the UPFC controller dynamic responses. Drawing on the constrained optimisation based on Newtons method together with the new UPFC model expressed in terms of nodal voltages, a systematic and general method for determining optimal reference inputs to UPFCs in steady-state operation is developed. The method is directly applicable to UPFCs operation with a high-level line optimisation control (LOC) for maximising the network operational benefit. By using a new continuation technique with adaptive parameter, the algorithm for solving the constrained optimisation problem extends substantially the region of convergence achieved with the conventional Newtons method. Having established the foundation provided by the comprehensive models developed for representing power systems with FACTS devices including the UPFC, the research, in the second part, focuses on real-time control coordination of power system controllers, with the main purpose of restoring power system static security following a disturbance or contingency. At present, as the cost of phasor measurement units (PMUs) and wide-area communication network is on the decrease, the research proposes and develops a new secondary voltage control where voltages at all of the load nodes are directly controlled, using measured voltages.
34
Cetin, Alper. "Design And Implementation Of A Voltage Source Converter Based Statcom For Reactive Power Compensation And Harmonic Filtering." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608307/index.pdf.
Full textAbstract:
In this thesis, design and implementation of a distribution-type, voltage source converter (VSC) based static synchronous compensator (D-STATCOM) having the
simplest converter and coupling transformer topologies have been carried out. The VSC STATCOM is composed of a +/- 750 kVAr full-bridge VSC employing selective harmonic elimination technique, a low-pass input filter, and a ∆
/Y connected coupling transformer for connection to medium voltage bus. The power stage of VSC based STATCOM is composed of water-cooled high voltage IGBT modules switched at 850 Hz for the elimination of 5th, 7th, 11th, 13th, 17th, 19th, 23rd,and 25th voltage harmonics. Special care has been taken in the laminated busbar design to minimize stray inductances between power semiconductors and dc link capacitor. Reactive power control is achieved by applying the phase angle control technique. The effect of input filter on total demand distortion has been investigated theoretically by mathematical derivations. The proposed VSC STATCOM has been implemented for reactive power compensation of Coal Preparation System in Kemerkö
y Thermal Power Plant. The field test results have shown the success of the implemented system in view of fast response in reactive power compensation, and minimum input current harmonic content, and compliance with the IEEE Std. 519-1992 even for the weakest power systems. The application of selective harmonic elimination technique and phase angle control to VSC STATCOM has led to optimum switching frequency and device utilization for high voltage IGBTs at the expense of slower response as compared to other PWM techniques.
35
Krtek, Jiří. "Numerická analýza přesypávaných mostních konstrukcí." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-227153.
Full textAbstract:
The topic of this Thesis is a study of the behavior of flexible metal large-span culverts during the construction and the operation. The aim is to analyze the behavior of the structure as a result of an unequally dropping support and a position of the load to the construction in relation to the soil cover height above the top of the steel construction. The Thesis is theoretical and based on the numerical parametric study.
36
王文廷. "Statistical Inference for Linear Models with Flexible Error Distributions." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/67319048907453712148.
Full textAbstract:
碩士國立交通大學
統計學研究所
96
In the thesis, we consider statistical inference for a general class of linear regression models. The assumption on the error distribution plays a crucial role for the development of an appropriate inference method. Here we examine several estimation approaches under four types of error distributions including symmetric (with light/heavy tails) and asymmetric distributions. In particular, we focus on the issues of robustness and efficiency. We also discuss how the existing methods are extended to the situation of censoring. Monte Carlo simulations are performed to evaluate the finite-sample performances of different methods.
37
Fritsch, Arno [Verfasser]. "Bayesian mixtures for cluster analysis and flexible modeling of distributions / by Arno Fritsch." 2010. http://d-nb.info/1008220604/34.
Full text
38
Wu, Jyan-cwan, and 吳建冠. "A Study on Efficient and Flexible Decentralized Multicast Key Distribution." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/w5358f.
Full textAbstract:
碩士世新大學
資訊管理學研究所(含碩專班)
96
Multicast communication is becoming the basis for a growing number of Internet based applications. The most common applications of multicast communication are video conference, online TV and on-line games. The secure distribution of services or messages by the server to all multicasting group members requires a security framework that requires an efficient and scalable way for distributing a group key to the eligible members. Most of the existing researches are focusing on group key and group members management, and can be divided into four types: centralized, decentralized, distributed, and hybrid schemes. In this thesis, we propose an efficient and flexible decentralized multicast key distribution scheme with less computational cost and more functionality. The main merits include: (1) the scheme needs no shared keys table between the registration center and all members; (2) a group key is distributed by servers to eligible members; (3) the computation cost is very low; (4) members and servers can authenticate each other; (5) our scheme is a nonce-based scheme which dose not have a serious time-synchronization problem; (6) the shared secret key distribution between dynamic participants is addressed in our proposed scheme, but is not investigated by other decentralized schemes.
39
Chia-Yu, Liu, and 劉家瑜. "Stress Distribution and Model Design of the Devices on Flexible and Rigid Substrate." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/02958602540023958478.
Full textAbstract:
碩士國立臺灣師範大學
光電科技研究所
98
The cost down is a critical issue for display industry and high density IC development. Before the product design, the TCAD simulation plays an important role to reduce R&D cycles and budget. For flexible display development, the characteristics are portable, lightweight, rugged, arbitrary sharpness, and unrestrained design. However, the electrical characteristics of TFTs may be degraded with mechanical bending, and leaded the panel failure. This paper used in TCAD software is specialized simulation of stress analysis from model building, incorporated into the material parameters, set intrinsic stress, imposed boundary conditions. Step by step, setup is completed that you can reach our want to know the stress and strain. It would help us to understand that the component of the stress concentration and improve IC model design a lot. Not only that, we can also change the material parameters, we can immediately simulate new features of IC components. In this paper, we try to do many different types of materials and bending on the different curvature, such as Top gate or bottom gate a-Si devices, solar cells, titanium or aluminum sandwich board. We also simulated the breakdown of the released energy (Energy release rate) when it broke down. Verifying and changing the model from paper, we expect this data that can contribute to stress analysis for the academic research.
40
Hussain, Awesar, Jaan H. Pu, and P. R. Hanmaiahgari. "Drag coefficient modelling study for flexible vegetation in open channel flow." 2018. http://hdl.handle.net/10454/16690.
Full textAbstract:
NoVegetation remains to be an important factor that can hinder the river flow. It needs innovative management scheme, in order to adapt these changes and ensure sustainability of their multiple usages. Vegetation plays an important role in floods and droughts adaptation within river system to alleviate any flood that may propagates from river to its surrounding. Vegetation within river can also retard its flow to cause building-up of deposition, and further adding to uncertainty of water use under extreme droughts. Due to these, it is important to study and understand vegetation drag behaviour toward flow in order to prevent flood risk and water security with hydrological drought in the basin and any other negative impact caused by it. In this study, an analytical approach for river flooding has been studied by improved representation of drag coefficient CD in flow velocity distribution modelling. The analysis of flow parameters, i.e. Reynolds number, on the drag coefficient CD has been conducted. The presented model has been used and analysed in open channel flows with flexible vegetation. In modelling, the flexible vegetated channel layers were divided into vegetation, top of vegetation and water layer zones in the model. The balance of forces for each layer has been established by validation using different reported measured data. The modelling results showed reasonably corresponding prediction of velocity profile in flows with flexible vegetation.
41
Cheng-Zong, Shieh. "An Efficient and Flexible Key Distribution Scheme for Conditional Access System in Pay-TV Systems." 2006. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0016-1303200709283901.
Full text
42
Liao, Chi-chou, and 廖啟州. "Effects temperature distribution on pavement damage and service life for freeway flexible pavements in Taiwan." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/9hpz8y.
Full textAbstract:
博士國立中央大學
土木工程研究所
97
Asphalt concrete (AC) is a sensitive material with temperature, its stiffness is greatly influenced by ambient temperature. As the temperature of the asphalt concrete increases, its stiffness decreases that may lead to rut occurring on the asphalt pavement from wheel loads. A decrease in asphalt concrete stiffness results in lower structural capacity to support vehicle loads. Therefore, the mechanical property of flexible pavement is affected by temperature deeply. In this study, based on field temperature measurements obtained from a test site simulating actual pavement structures of freeways, the pavement temperature distribution in Taiwan’s freeway were discussed in details. The results indicated the temperature of pavement changes with the climate within a year. Since the thickness of freeway pavements in Taiwan is relatively thick, the temperature distribution of the AC and bituminous treated base (BTB) layers was found to be different. Thus, separate temperature prediction model was established according the characteristic of each asphalt layer. Based on the test results, the effective temperature depth of pavement was affected by the temperature distribution of AC and BTB. Through the analysis on pavement structural responses, it is indicated that the 1/2 depth of AC layer and the 2 cm under the top of BTB layer are considered appropriate depth as effective temperature for strautural analysis of pavements. Also, separate temperature prediction model were established for AC and BTB layers, respectively. Besides, considering the pavement temperature variation within 24 hours and traffic loads applied on freeway pavement, the damage per pass of each load axle was calculated for different times in a day. It was found that the damage increases as pavement temperature increases in the daytime and reduces as the temperature decreases in nighttime. In other words, the temperature cycle within a day has a great effect on the damage level caused by traffic loads in flexible pavement. Moreover, with the thick pavement structure used by Taiwan’s freeway, it was found that the fatigue damage will occur earlier than permanent deformation. Various time-durations, ranging from 1-hour to 1-year, for average temperature input to predict pavement service life and/or design ESAL were evaluated carefully. The effects of pavement average temperature of various time periods and traffic loads on pavement damage ratio and service life were determined. It was found that the 1-hr time period with average pavement temperature could simulate the actual response of freeway pavement under the pavement temperature cycle and traffic loadings. Segmentation of the pavement temperature and traffic loading into 1-hr period will produce a pavement damage ratio greater than that into 1-yr period. This indicates that the actual damage of freeway pavement is more severe than that expected by considering the yearly average temperature only. The adjustment coefficient of pavement service life established the relationship for the apparent difference between the yearly based average temperature and the real situation of in-situ pavement temperature. Using the pavement service life calculated using 1 hr period as the basis, a correlation is established for different time periods for average temperature. It provides an exact relationship obtained from the average temperature of 1 hr period and a yearly period for pavement structure design and the estimation of remaining pavement service life.
43
Shieh, Cheng-Zong, and 謝丞宗. "An Efficient and Flexible Key Distribution Scheme for Conditional Access System in Pay-TV Systems." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/20294910213955216112.
Full textAbstract:
碩士國立清華大學
資訊系統與應用研究所
94
The pay-TV system becomes one of the popular applications in recent years because of the advancement in modern network technique. The Conditional Access System (CAS) is the essential function to provide the channel protection in pay-TV system. Only the authorized subscribers can precisely receive the TV program, and they were charged by the service provider according to their subscription. In this paper, we defined a new pay-TV model named Flexible-PPC (F-PPC) which allowed subscribers subscribe to a large number of channels and unsubscribed each of them anytime. In order to accomplish the requirements of F-PPC, we also proposed a CAS with a four-level hierarchical key management scheme. The proposed CAS can be applied on a large scale pay-TV system with lots of subscribers and channels. The subscribers can freely choose the channels. Besides, subscribers can subscribe and unsubscribe channels arbitrarily, and the proposed CAS can also revoke illegal subscribers rapidly.
44
Chen, Junliang. "A Monte Carlo EM algorithm for generalized linear mixed models with flexible random effects distribution." 2001. http://www.lib.ncsu.edu/etd/public/etd-58272011010143040/etd.pdf.
Full text
45
Pu, Jaan H., Awesar Hussain, Yakun Guo, Nikolaos Vardakastanis, P. R. Hanmaiahgari, and Dennis Lam. "Submerged flexible vegetation impact on open channel flow velocity distribution: An analytical modelling study on drag and friction." 2019. http://hdl.handle.net/10454/17136.
Full textAbstract:
YesIn this paper, an analytical model that represents the streamwise velocity distribution for open channel flow with submerged flexible vegetation is studied. In the present vegetated flow modelling, the whole flow field has been separated into two layers vertically: a vegetated layer and a non-vegetated free-water layer. Within the vegetated layer, an analysis of the mechanisms affecting water flow through flexible vegetation has been conducted. In the non-vegetated layer, a modified log-law equation that represents the velocity profile varying with vegetation height has been investigated. Based on the studied analytical model, a sensitivity analysis has been conducted to assess the influences of the drag and friction coefficients on the flow velocity. The investigated ranges of drag and friction coefficients have also been compared to published values. The findings suggest that the drag and friction coefficient values are non-constant at different depths and vegetation densities, unlike the constant values commonly suggested in literature. This phenomenon is particularly clear for flows with flexible vegetation, which is characterised by large deflection.
46
Carvalho, Micael Luís Morais. "An Overview of Methods for Control of Flexible Resources." Master's thesis, 2016. http://hdl.handle.net/10316/81592.
Full textAbstract:
Dissertação de Mestrado Integrado em Engenharia Electrotécnica e de Computadores apresentada à Faculdade de Ciências e TecnologiaA recurrent subject related with the electrical grids in the last years, is the necessity to adopt sustainable energy policies. Due to massive raises in the greenhouse gas emissions, the planet Earth has suffered serious consequences. The European Union, trying to reduce this emissions, has played an important role, with the financing of enormous projects with the aim to improve the Power Quality (PQ) and at the same time, reduce the greenhouse gas emissions, for a better ambient and a better service. Two of those projects are the Increase and the Story. The principal ambition of these two projects is to study and develop new controls to permit a better penetration and at the same time, a better control of the distributed renewable energy sources (DRES) in the distribution network. In the case of the Story, the aim is to use storage technologies to this end.Distribution networks are recently becoming a target of this intensive research. The increasing penetration of the distributed renewable energy sources, such as photovoltaic panels (PV) and wind generation, as well as flexible load consumption units, have influence the network operation. Normally, the Distribution System Operator (DSO) would strive to reinforce the grid through additional investments to deal with this issues. This investment can cause technical problems in the grid, although, this new development can also provide a potential source of flexibility from the network users and thus a desirable source of solutions for the grid operations. With appropriate approaches to conjure and to use this flexibility, the DSO can increase hosting capacity with the existing grid infrastructure, deferring grid reinforcement investments.The ambition of my master thesis is, in collaboration with the Laboratory of Energy Policy from the University of Ljubljana, to study the effects of the different types of controls in a distribution network, to allow the injection of power from DRES, keeping all the network parameters inside the regulated levels, allowing this flexibility aforementioned. For that, was used the Increase simulation platform to simulate a Rural Network with the parameters and characteristics close to a real one.This is a first part in this two European projects, with this results, they will be used for further investigation. Is essential to deliver new tools and methods to the DSO to allow a higher increase of distributed renewable energy sources in the network, because, with this inclusion will be a big step to a fossil independent networks.
Um assunto recorrente relacionado com as redes elétricas durante os últimos anos, é a necessidade de adotar politicas energeticamente sustentáveis. Devido ao enorme crescimento nas emissões de gases de estufa, o nosso planeta tem vindo a sofrer graves consequências.A União Europeia tem tido um papel importante no combate a este crescimento das emissões, com o financiamento de vários projetos com o fim de melhorar a qualidade de energia e ao mesmo tempo, reduzir as emissões dos gases de estufa, para um melhor ambiente e um serviço melhorado.Dois destes projetos são o Increase e o Story. A principal ambição destes dois projetos, é o estudo e o desenvolvimento de novos tipos de controlo, que permitam uma melhor penetração e ao mesmo tempo, um controlo improvado das distributed renewable energy sources (DRES) nas redes de distribuição elétricas. No caso do programa Story são usadas unidades de armazenamento para este fim.As redes de distribuição elétricas têm vindo a ser alvo de uma pesquisa intensiva. A penetração das DRES, como fotovoltaicas (PV) e energia eólica, bem como as cargas com consumo flexível, influenciam a operação das redes. Normalmente, o operador destas redes opta pela via do investimento para lidar com estes problemas, no entanto, este mesmo investimento pode provocar novos problemas técnicos na rede de energia. Com estes recentes desenvolvimentos, os consumidores podem vir a ser uma fonte potencial de flexibilidade para a rede, sendo uma solução desejável para os problemas na operação da rede.Com um apropriado uso desta flexibilidade, o DSO pode aumentar a capacidade da rede usando apenas a infraestrutura já instalada, evitando assim custos da instalação de novos equipamentos.Esta dissertação tem como ambição, numa colaboração com o Laboratory of Energy Policiy da Universidade de Ljubljana, estudar os efeitos de diferentes tipos de controlos numa rede de distribuição, para assim, permitir uma máxima injeção de energia das fontes renováveis, mantendo todos os parâmetros dentro dos valores regulados. Para isso, foi usada a plataforma de simulação do Increase para simular uma rede rural com parâmetros e características baseadas numa rede real.Este é uma primeira aproximação dos dois projetos acima referidos, sendo que estes resultados irão ser usados em investigações futuras. O desenvolvimento de novas ferramentas e métodos para o DSO permitir uma maior penetração de DRES na rede, é de elevada importância, pois com esta inclusão vai permitir uma maior independência dos combustíveis fósseis.
47
Lowndes, Gillian Claire. "The need for a flexible and discretionary system of marital property distribution in the South African law of divorce." Diss., 2014. http://hdl.handle.net/10500/18819.
Full textAbstract:
Substantive gender equality has yet to be achieved in South Africa. As such, when a decision is made for one of the spouses to a civil marriage to stay at home and care for the children born of the marriage, or make career sacrifices to care for children, that spouse is usually the wife. As a result, while the husband continues to amass wealth and grow his earning potential, the wife is unable to do so. In circumstances where such spouses are married out of community of property or subject to the accrual system with onerous exclusion clauses in the antenuptial contract, the wife may be left with little more than a claim for rehabilitative maintenance in the event of a divorce. The courts only have the discretion to make an equitable distribution of marital property in civil marriages with complete separation of property concluded prior to 1 November 1984 (or 2 December 1988) and customary marriages. It is arguable that this limitation of the judicial discretion violates the equality clause contained in the Constitution of the Republic of South Africa, 1996. A broad judicial discretion to equitably redistribute the spouses’ assets upon divorce is therefore proposed in this dissertation.Private Law
LL.M.
48
Shields, Jean-Philippe. "Élaboration du modèle conceptuel flexible et extensible d'une architecture logicielle orientée-objet permettant la parallélisation et la distribution d'une architecture de simulation séquentielle /." 2007. http://www.theses.ulaval.ca/2007/24474/24474.pdf.
Full text
49
Aguiar, Moya José Pablo 1981. "Development of reliable pavement models." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-08-3743.
Full textAbstract:
As the cost of designing and building new highway pavements increases and the number of new construction and major rehabilitation projects decreases, the importance of ensuring that a given pavement design performs as expected in the field becomes vital. To address this issue in other fields of civil engineering, reliability analysis has been used extensively. However, in the case of pavement structural design, the reliability component is usually neglected or overly simplified. To address this need, the current dissertation proposes a framework for estimating the reliability of a given pavement structure regardless of the pavement design or analysis procedure that is being used.
As part of the dissertation, the framework is applied with the Mechanistic-Empirical Pavement Design Guide (MEPDG) and failure is considered as a function of rutting of the hot-mix asphalt (HMA) layer. The proposed methodology consists of fitting a response surface, in place of the time-demanding implicit limit state functions used within the MEPDG, in combination with an analytical approach to estimating reliability using second moment techniques: First-Order and Second-Order Reliability Methods (FORM and SORM) and simulation techniques: Monte Carlo and Latin Hypercube Simulation.
In order to demonstrate the methodology, a three-layered pavement structure is selected consisting of a hot-mix asphalt (HMA) surface, a base layer, and subgrade. Several pavement design variables are treated as random; these include HMA and base layer thicknesses, base and subgrade modulus, and HMA layer binder and air void content. Information on the variability and correlation between these variables are obtained from the Long-Term Pavement Performance (LTPP) program, and likely distributions, coefficients of variation, and correlation between the variables are estimated. Additionally, several scenarios are defined to account for climatic differences (cool, warm, and hot climatic regions), truck traffic distributions (mostly consisting of single unit trucks versus mostly consisting of single trailer trucks), and the thickness of the HMA layer (thick versus thin).
First and second order polynomial HMA rutting failure response surfaces with interaction terms are fit by running the MEPDG under a full factorial experimental design consisting of 3 levels of the aforementioned design variables. These response surfaces are then used to analyze the reliability of the given pavement structures under the different scenarios. Additionally, in order to check for the accuracy of the proposed framework, direct simulation using the MEPDG was performed for the different scenarios. Very small differences were found between the estimates based on response surfaces and direct simulation using the MEPDG, confirming the accurateness of the proposed procedure.
Finally, sensitivity analysis on the number of MEPDG runs required to fit the response surfaces was performed and it was identified that reducing the experimental design by one level still results in response surfaces that properly fit the MEPDG, ensuring the applicability of the method for practical applications.text
50
Petitclair, Patrice. "Modélisation et Commande de structures FACTS : (Flexible Alternative CUITent Transmission System) Application au STATCOM (STATic COMpensator)." Phd thesis, 1997. http://tel.archives-ouvertes.fr/tel-00909634.
Full textAbstract:
Le problème de la maîtrise du transport de l'énergie électrique a donné naissance au projet FACTS (Flexible Alternative Current Transmission System ! Pour améliorer la flexibilité des réseaux de transport existants. Le ST A TCOM (ST ATic COMD*~ n s ator) est un dispositif FACTS dédié à la compensation d'énergie réactive transitant sur le réseau . L'évolution des composants d'électronique de puissance a apporté des solutions technologiques pour la réalisation des structures onduleurs du STATCOM. En tenant compte des diverses structures présentées, un modèle dynnamique est construit en utilisant la théorie du modèle moyen généralisé. Il est ensuite validé avec le modèle topologique, lequel décrit le comportement fin de l'onduleur. Afin d' avoir un contrôle robuste du courant réactif du dispositif, une loi de commande non linéaire est élaborée à partir de la théorie de la linéarisation par bouclage. La linéarisation est obtenue au détriment des comportements dynamiques du courant actif et de la tension continue de l' onduleur. Une optimisation de la loi de conunande est proposée afin de maîtriser le comportement dynamique de toutes les variables du dispositif. Cette loi de commal1de est validée sur le modèle topologique après avoir abordé le problème des filtres de mesure. La mise en place de la linéarisation par bouclage nécessite une connaissance des valeurs des composants de la structure. Une estimation ainsi qu'une correction de l'erreur commise sur ces grandeurs sont alors proposées. Le modèle du ST A TCOM avec ses lois de commande est ensuite inséré dans un logiciel destiné à l' étude du comportement dynamique de réseaux (EUROSTAG). A cet effet, le modèle mis au point prend en compte le comportement dynamique de la structure du ST A TCOM, et apporte une richesse supplémentaire pour l 'étude dynamique des réseaux. L'intérêt de la loi de commande optimisée est nus en évidence comparativement aux solutions classiques.