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Nguyen, Duy Huu Manh. "Analysing electricity markets with evolutionary computation." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2002. http://theses.library.uwa.edu.au/adt-WU2003.0018.
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The use of electricity in 21st century living has been firmly established throughout most of the world, correspondingly the infrastructure for production and delivery of electricity to consumers has matured and stabilised. However, due to recent technical and environmental–political developments, the electricity infrastructure worldwide is undergoing major restructuring. The forces driving this reorganisation are a complex interplay of technical, environmental, economic and political factors. The general trend of the reorganisation is a dis–aggregation of the previously integrated functions of generation, transmission and distribution, together with the establishment of competitive markets, primarily in generation, to replace previous regulated monopolistic utilities. To ensure reliable and cost effective electricity supply to consumers it is necessary to have an accurate picture of the expected generation in terms of the spatial and temporal distribution of prices and volumes. Previously this information was obtained by the regulated utility using technical studies such as centrally planned unit–commitment and economic–dispatch. However, in the new deregulated market environment such studies have diminished applicability and limited accuracy since generation assets are generally autonomous and subject to market forces. With generation outcomes governed by market mechanisms, to have an accurate picture of expected generation in the new electricity supply industry, it is necessary to complement traditional studies with new studies of market equilibrium and stability. Models and solution methods have been developed and refined for many markets, however they cannot be directly applied to the generation market due to the unique nature of electricity, having high inelastic demand, low storage capability and distinct transportation requirements. Intensive effort is underway to formulate solutions and models that specifically reflect the unique characteristics of the generation market. Various models have been proposed including game theory, stochastic and agent–based systems. Similarly there is a diverse range of solution methods including, Monte–Carlo simulations, linear–complimentary and quadratic programming. These approaches have varying degrees of generality, robustness and accuracy, some being better in certain aspects but weaker in others. This thesis formulates a new general model for the generation market based on the Cournot game, it makes no conjectures about producers’ behaviour and assumes that all electricity produced is immediately consumed. The new formulation characterises producers purely by their cost curves, which is only required to be piece–wise differentiable, and allows consumers’ characteristics to remain unspecified. The formulation can determine dynamic equilibrium and multiple equilibria of markets with single and multiple consumers and producers. Additionally stability concepts for the new market equilibrium is also developed to provide discrimination for dynamic equilibrium and to enable the structural stability of the market to be assessed. Solutions of the new formulation are evaluated by the use of evolutionary computation, which is a guided stochastic search paradigm that mimics the operation of biological evolution to iteratively produce a population of solutions. Evolutionary computation is employed as it is adept at finding multiple solutions for underconstrained systems, such as that of the new market formulation. Various enhancements to significantly improve the performance of the algorithms and simplify its application are developed. The concept of convergence potential of a population is introduced together with a system for the controlled extraction of such potential to accelerate the algorithm’s convergence and improve its accuracy and robustness. A new constraint handling technique for linear constraints that preserves the solution’s diversity is also presented together with a coevolutionary solution method for the multiple consumers and producers market. To illustrate the new electricity market formulation and its evolutionary computation solution methods, the equilibrium and stability of a test market with one consumer and thirteen thermal generators with valve point losses is examined. The case of a multiple consumer market is not simulated, though the formulation and solution methods for this case is included. The market solutions obtained not only confirms previous findings thus validating the new approach, but also includes new results yet to be verified by future studies. Techniques for market designers, regulators and other system planners in utilising the new market solutions are also given. In summary, the market formulation and solution method developed shows great promise in determining expected generation in a deregulated environment.
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Silva, Thayze D'Martin Costa da 1988. "Princípio do equivalente certo no planejamento da operação de sistemas hidrotérmicos." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259879.
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Orientadores: Secundino Soares Filho, Mônica de Souza ZambelliDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: O Princípio do Equivalente Certo (PEC) garante que as abordagens determinística e estocástica são equivalentes na otimização de sistemas dinâmicos estocásticos quando satisfeitas certas condições. É possível que o problema de planejamento da operação energética (POE) se aproxime de satisfazer as condições do PEC, apesar de não atendê-las teoricamente. Assim, o objetivo desta dissertação é analisar a validade do PEC no âmbito da Programação Dinâmica aplicado ao POE de sistemas hidrotérmicos constituídos de um único reservatório e avaliar o impacto da violação de cada condição. As hipóteses do PEC foram analisadas progressivamente por meio da comparação dos resultados dos modelos considerados, desde o ideal que atende teoricamente às condições, até o mais próximo da realidade. Foram observadas diferenças pouco significativas entre as políticas de operação determinística e estocástica, indicando que o modelo de POE se aproxima de atender às condições do PEC. Uma consequência imediata deste estudo seria que a abordagem determinística do problema de POE para sistemas hidrotérmicos com um único reservatório pode ser tão eficaz quanto as abordagens estocásticas
Abstract: Certainty Equivalence Principle (CEP) ensures that deterministic and stochastic approaches are equivalent in stochastic dynamic systems optimization when some assumptions hold. It is possible that Long Term Hydrothermal Scheduling (LTHS) problem is close to attaining CEP¿s assumptions, although it does not attain them theoretically. Thus, the objective of this dissertation is to analyze the validity of CEP in Dynamic Programming framework applied to single reservoir LTHS problem and to evaluate the impacts of each CEP¿s condition violation. The CEP¿s conditions were progressive analyzed by comparison of the considered models results from an ideal case where theoretically assumptions hold until a case study closer to reality. Slight differences were observed between deterministic and stochastic operation policies, indicating that LTHS model is close to attain the CEP¿s conditions. An immediate consequence of this study would be that deterministic approach for the single reservoir LTHS problem can be as effective as stochastic ones
Mestrado
Energia Eletrica
Mestra em Engenharia Elétrica
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Smith, William Corbett. "Analysis of variances in electric power system simulation for production cost." Ohio : Ohio University, 1991. http://www.ohiolink.edu/etd/view.cgi?ohiou1173467167.
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Feng, Xiaoming. "On the probabilistic production simulation of electric power systems using equivalent load duration curve methods." Ohio : Ohio University, 1990. http://www.ohiolink.edu/etd/view.cgi?ohiou1172779312.
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Zaag, Nader. "Fast simulation of cascading outages with islanding." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112588.
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This thesis proposes an efficient power system simulator to estimate the automatic sequence of events that follow a fault contingency leading to islanding and cascading outages. The simulator is based on a quasi-steady state model that includes island identification, under-frequency load shedding, over-frequency generator tripping, and island load flow. Contingencies can include the outage of generators, loads, or transmission lines. Often times, a fault of one or two of these power system elements can lead to many cascaded outages and system islanding. The simulator utilizes an innovative method that analyzes the null space of the DC load flow susceptance matrix to identify system islands after each disturbance. Once system islands have been determined, each island power imbalance is calculated and the simulator determines based on the power imbalance in each island whether any load shedding, generator tripping, or primary frequency regulation is required. Once these corrective actions are completed each island will either have been found to balance power or will experience blackout. In the islands that have balanced power, a load flow is computed to see if all line flow constraints are satisfied. Any lines with flow constraint violations are faulted, and the iterative process is repeated under all line flow constraints are satisfied.The results demonstrate the ability of the simulator to quickly and efficiently predict a system's response to contingencies leading to cascading outages and islanding. Simulations were conducted on a 10-bus 13-line network, a 24-bus 38-line network, and a 72-bus 119-line network.
This thesis also examined the highly complex mixed-integer linear problem of identifying the optimum initial outage in the sense that it would cause the maximum amount of load shedding through islanding. The results on a three-line, three-bus test properly identified the line whose initial outage caused overflows leading to system separation and maximum loss of load.
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Parikh, Rajiv D. "PC based simulation software package for an uninterruptable power supply." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-11242009-020238/.
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Atkinson-Hope, Gary. "An integrated programme for power systems simulation using personal computers (PC's)." Thesis, Cape Technikon, 1993. http://hdl.handle.net/20.500.11838/1147.
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Thesis (Masters Diploma (Technology)--Cape Technikon, Cape Town, 1993The research objectives were to: Formulate a training structure covering conventional power systems topics; Research existing PC based power systems software resources; Develop a structure for a PC based power systems course; Research the capabilities of the software resources chosen; Develop a structure for a modern PC based power systems course taking into account the capabilities and limitations of the selected software programs; Develop for the PC based power systems course, task orientated computer based laboratory set-ups. The set-ups provide: An introduction into the topics concerned; An explanation of the usage of each program applied, where usage means an explanation of the Input and Output Data of each program; User friendly simulation experiments. These set-ups, together with software programs and a personal computer integrate into a training programme and realize a power systems simulation course.
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Arès, Jean-Michel. "A knowledge-based model and simulator for alarm and protection systems of power networks /." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63921.
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Arata, John Paul III. "Simulation and control strategy development of power-split hybrid-electric vehicles." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42790.
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Power-split hybrid-electric vehicles (HEVs) provide two power paths between the internal combustion (IC) engine and the driven wheels through gearing and electric machines (EMs) composing an electrically variable transmission (EVT). EVTs allow IC engine control such that rotational speed is independent of vehicle speed at all times. By breaking the rigid mechanical connection between the IC engine and the driven wheels, EVTs allow the IC engine to operate in the most efficient region of its characteristic brake specific fuel consumption (BSFC) map. If the most efficient IC engine operating point produces more power than is requested by the driver, the excess IC engine power can be stored in the energy storage system (ESS) and used later. Conversely, if the most efficient IC engine operating point does not meet the power request of the driver, the ESS delivers the difference to the wheels through the EMs. Therefore with an intelligent supervisory control strategy, power-split architectures can advantageously combine traditional series and parallel power paths.
In the first part of this work, two different power-split HEV powertrains are compared using a two-term cost function and steady-state backward-looking simulation (BLS). BLS is used to find battery power management strategies that result in minimized fuel consumption over a user-defined drive-cycle. The supervisory control strategy design approach amounts to an exhaustive search over all kinematically admissible input operating points, leading to a minimized instantaneous cost function. While the approach provides a valuable comparison of two architectures, non-ideal engine speed fluctuations result. Therefore, in the second part of the work, two approaches for designing control strategies with refined IC engine speed transitions are investigated using high-fidelity forward-looking simulation (FLS). These two approaches include: i) smoothing the two-term cost function optimization results, and ii) introducing a three-term cost function. It is found that both achieve operable engine speed transitions, and result in fuel economy (FE) estimates which compare well to previous BLS results. It is further found that the three-term cost function finds more efficient operating points than the smoothed two-term cost function approach. From the investigations carried out in parts one and two of this work, a two-phase control strategy development process is suggested where control strategies are generated using efficient steady-state BLS models, and then further tested and verified in high-fidelity FLS models. In conclusion, the FLS results justify the efficacy of the two-phased process, suggesting rapid and effective development of implementable power-split HEV supervisory control strategies.
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Remy, Ghislain. "Commande optimisée d'un actionneur linéaire synchrone pour un axe de positionnement rapide." Phd thesis, Paris, ENSAM, 2007. http://tel.archives-ouvertes.fr/tel-00281529.
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Les moteurs linéaires sont devenus des composants incontournables dans le domaine de la conception des machines de production. L'actionneur synchrone à aimants permanents (PMLSM) constitue le principal composant et permet aujourd'hui d'obtenir des performances nettement supérieures à celles de son homologue rotatif accouplé à un système de transformation de mouvement. Cependant, pour utiliser ces constituants de façon optimale, il est nécessaire de prendre en compte dans la commande les spécificités de ce type d'actionneur. En effet, des phénomènes électriques et magnétiques, tels que les forces électromotrices non-sinusoïdales, la saturation des inductances et les forces de détente, génèrent des forces ondulantes perturbatrices pour la partie mécanique. L'objectif de cette étude est donc, dans un premier temps, d'améliorer la modélisation de ces moteurs linéaires en vue de leur commande. Des méthodes analytiques et éléments-finis sont utilisées pour quantifier l'importance de ces phénomènes sur la force de poussée. Puis, dans une deuxième partie, nous définissons les structures de commande optimales permettant de prendre en compte les phénomènes retenus. Le formalisme du Graphe Informationnel Causal (GIC), développé par le laboratoire L2EP, est utilisé pour représenter et définir de façon systématique les structures de commande retenues. Les méthodologies d'inversion du GIC sont détaillées pour permettre la définition des structures de commande en Boucles Fermées et Non-Fermées. Les structures classiques de commande industrielles sont analysées et de nouvelles structures de commande sont proposées pour la commande en force d'un moteur linéaire LMD10-050 de la société ETEL.
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劉紅進 and Hongjin Liu. "Implementation of a multi-agent based power market simulator." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31224829.
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Garrett, Bretton Wayne. "Digital simulation of power system protection under transient conditions." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/27303.
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This work demonstrates the use of digital simulation for analyzing protection
system performance. For studies of complex, multi-relay protection systems, digital simulation provides utility engineers with an attractive alternative to relay testing techniques. The cost of digital simulation facilities can be lower than the cost of comparable testing facilities; relay hardware does not have to be made available for the test laboratory.
Digital simulation would ordinarily be impractical for security and dependability studies, due to the thousands of individual simulations involved. The number of simulations needed can be greatly reduced by using a technique called "numerical logic replacement" for implementing the protection scheme logic. This unconventional technique makes near-misoperation visible from individual simulations.
The likelihood of overlooking potential misoperation is thus much lower than with the usual direct (Boolean) implementations.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Woodburn, David. "Modeling and Simulation of All-electric Aircraft Power Generation and Actuation." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6037.
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Modern aircraft, military and commercial, rely extensively on hydraulic systems. However, there is great interest in the avionics community to replace hydraulic systems with electric systems. There are physical challenges to replacing hydraulic actuators with electromechanical actuators (EMAs), especially for flight control surface actuation. These include dynamic heat generation and power management.
Simulation is seen as a powerful tool in making the transition to all-electric aircraft by predicting the dynamic heat generated and the power flow in the EMA. Chapter 2 of this dissertation describes the nonlinear, lumped-element, integrated modeling of a permanent magnet (PM) motor used in an EMA. This model is capable of representing transient dynamics of an EMA, mechanically, electrically, and thermally.
Inductance is a primary parameter that links the electrical and mechanical domains and, therefore, is of critical importance to the modeling of the whole EMA. In the dynamic mode of operation of an EMA, the inductances are quite nonlinear. Chapter 3 details the careful analysis of the inductances from finite element software and the mathematical modeling of these inductances for use in the overall EMA model.
Chapter 4 covers the design and verification of a nonlinear, transient simulation model of a two-step synchronous generator with three-phase rectifiers. Simulation results are shown.Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
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Onwunta, Onwunta Emea Kalu. "Modelling and simulation of the impacts of distributed generation integration into the smart grid." Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/1200.
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Thesis submitted in fulfilment of the requirements for the degree
Doctor of Technology: Electrical Engineering
in the Faculty of Engineering
at the Cape Peninsula University of Technology
2014Distributed generation (DG) has been reincarnated after its demise by centralised generation. While economy of scale and efficiency are the advantages of the latter, deregulation of the electricity market, environmental concerns and the need to arrest dwindling reserve margins have necessitated the rebirth of the former. Indeed, a full circle has therefore evolved with generation being ‘embedded’ in distribution systems and ‘dispersed’ around the system rather than being located and dispatched centrally or globally. This development is in tandem with the history of industrial revolutions that started from energy and moved through services and communication and back to energy. South Africa is not immune to the global energy, especially tertiary energy, challenge phenomenon. At the peak of the 2007-2008 energy crisis, her generation net reserve margin fell below 10% – well below conventional industry benchmark of at least 15%. Also South Africa is Africa’s largest emitter of CO2 contributing over 40% of Africa’s total CO2 emissions. Therefore, DG’s relevance to South Africa is quite obvious. However, DG integration into distribution networks leads to a number of challenges. For instance, with significant penetration of DG power flow reversal may be experienced and the distribution network will no longer be a passive circuit. This underscores the crucial role of ICT in active distribution network occasioned by DG and especially the emergent of “prosumerism” (a hitherto consumer also becoming a producer). Therefore, a smart grid and similar phrases have all been used to describe a “digitised” and intelligent version of the present-day power grid. There are immense benefits derivable from modelling and simulation. Consequently, a typical radial distribution network model has been developed to evaluate the considerable impacts of DG integration. The modelling and simulation of the network are accomplished using the DIgSILENT PowerFactory simulation package. Impacts of DG on voltage profile, fault level, voltage stability and protection coordination have been investigated and their possible mitigation measures proferred. The results reveal that for a particular DG type its impacts depend mainly on its capacity and point of connection relative to a given load type. Smart grid technology addresses some of these impacts through its inherent capability which includes peer-to-peer relay communication for protective devices on the distribution feeder as well as communication to the DG facility.
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Tai, Sio Un. "Power quality study in Macau and virtual power analyzer." Thesis, University of Macau, 2012. http://umaclib3.umac.mo/record=b2586277.
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Wise, Michael Anthony. "A variance reduction technique for production cost simulation." Ohio : Ohio University, 1989. http://www.ohiolink.edu/etd/view.cgi?ohiou1182181023.
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Lai, Tsz-ming Terence, and 黎子明. "Harmonic simulation of traction system." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B3122281X.
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Swahn, Azavedo Michael. "Simulating the Swedish Electric Energy Production : An optimization perspective." Thesis, Uppsala universitet, Elektricitetslära, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-221165.
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Production of electric energy is continuously affected by many factors. Therefore, tools for predicting the future production are needed. In turn, the production affects the electric energy price, which is set on electric energy exchanges. This thesis is intended to find out if the software SDDP can be used for hydrothermal power production simulations in the Nord pool area. By building a simplified model of the electric energy production in Sweden with a focus on hydro, thermal and wind power, the intention is to see how the model is affected by different conditions. The investigated conditions are several; higher and lower water inflows to the hydro power reservoirs; different amounts of installed wind power production; different price levels of emission allowances for CO2. By using the simulation software SDDP, more wind power was seen to lower the electric energy prices, as well as reduce the need of transmission of power from the northern to the southern parts of Sweden. In the simulation, Sweden was divided into four areas, connected where the main bottlenecks in the power grid are located. Water inflows to the reservoirs are crucial in the model. Actual inflow data can be bought from SMHI. However, due to the limited thesis budget, estimations were constructed instead. The estimations were difficult to make and turned out to be too high. Consequently, no reliable evaluation of the SDDP software could be done using this data.
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Stefopoulos, Georgios Konstantinos. "Quadratic power system modeling and simulation with application to voltage recovery and optimal allocation of VAr support." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29695.
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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010.Committee Chair: Meliopoulos, A. P. Sakis; Committee Member: Deng, Shijie; Committee Member: Divan, Deepakraj; Committee Member: Harley, Ronald; Committee Member: Taylor, David. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Aminou, Moussavou Anges Akim. "Modelling and analysis of microgrid control techniques for grid stabilisation." Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/1184.
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Thesis submitted in fulfilment of the requirements for the degree
Master of Technology: Electrical Engineering
in the Faculty of Engineering
at the
Cape Peninsula University of Technology
2014In recent times, renewable energy-based distributed generation (DG) has captivated the industrial sector and on a global scale this has become a leading research area. Distributed generation using wind, solar energy or biomass as a source of energy can produce electricity on a small scale. Therefore, there is a strong focus on using renewable energy as a safe alternative source of energy, especially because it can in future play a dominant role in the world’s energy production and help to tackle the increase of global warming caused by fossil energy. However, a major problem facing renewable energies is that they are highly dependent on weather conditions. Since the power generated by DG, as well as consumption, depends on the weather conditions, irregularity of production and consumption leads to frequency and voltage fluctuations, and it can become difficult to determine and monitor consumer usage at any given time. Distributed generation can then be subjected to discrepancies in consumer usage and this can lead to severe overloading. As a result, microgrids powered by DG, operating in a single, stand-alone controllable system mode, face new challenges in terms of balancing a cluster of loads. Balancing a cluster of loads by making sure at all times that the entire system operates without overloading, is an essential requirement for the proper operation of a power system. The microgrid load considered in this project is the sum of sensitive and non-sensitive loads, respectively 5 kW and 100 kW, which constitute load requirement of one village; this total load required by a number of villages is called a cluster load. Depending on the input power generated by a DG-based photovoltaic (PV) system, these loads can be controlled using a logic control switch (LCS). When the power produced is less than the minimum load required by a component of a cluster, overloading occurs. The purpose of using an LCS is to ensure that a stable system is maintained under various loads and resource conditions. An LCS is used to continuously monitor and adjust load through circuit breakers. It is a good alternative to load balancing for a cluster of villages in rural area where a microgrid is operating in stand-alone mode. The focus of this research is to design a photovoltaic system with a maximum capacity of 1 MW providing power to a cluster of rural villages, and operating in stand-alone mode, and then to apply different control techniques (droop control, dq0 reference frame + proportional integral (PI) controller, and PI controller alone) at the inverter terminal of the PV system, in order to evaluate the stability of the output voltage. Another goal of the research is to develop an energy management system (EMS) algorithm to support the PV system in reducing loads. Therefore, a iii stable system under various load and resource conditions, as well as suitable control mechanisms are required to model a PV system. There is a need for the modelling of a PV array using a physical modelling block in MATLAB (SIMULINK) software. The state flow provided by SIMULINK is used in this project to develop an algorithm for load balancing. The state flow gives possibilities of modelling complex algorithms by combining graphical and tabular representations to create sequential decision logic, derived from state transition diagrams and tables, flow charts and truth tables. Furthermore, the design of a microgrid using photovoltaic DG and an energy management system, has been developed. The present work mainly consists of a stand-alone microgrid operation, where the power generated must be equal to the load power. In addition, different control methods, consisting of a dq0 reference frame + PI controller, are analysed at the invertor terminal. Subsequently an LCS algorithm is developed; this is required to maintain the system within certain limits and prevents overloading. LCS algorithms are based on a flowchart and allow switching automatically selected loads, depending on the power (solar radiation) available. In addition, a flow chart provides an easy way of using a graphical transition state and state chart to establish a set of rules for the system. The simulation results show that both droop control and a dq0 reference frame + PI controller are much better than a PI controller alone; these results also compared well with similar studies found in the literature. Also, these results are further improved with an EMS in order to maintain the output voltage of the microgrid, by switching on and off certain loads depending on the input power. The modelling of the microgrid using DG, based on photovoltaic systems with a maximum capacity of 1 MW, supports and improves the PV system by reducing loads. Moreover, droop control, and dq0 transformation + PI control present a better result than PI controller alone.
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Girouard, Pierre. "Un système expert pour la gestion en temps réel des alarmes dans un réseau électrique /." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63940.
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Shi, Benyun. "Computational methods and mechanisms for evaluating and enhancing the robustness of energy distribution systems." HKBU Institutional Repository, 2012. https://repository.hkbu.edu.hk/etd_ra/1408.
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Liu, Kai, and 劉愷. "Optimal dispatch and management for smart power grid." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46336680.
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Conradie, Antonie Eduard. "Performance optimization of engineering systems with particular reference to dry-cooled power plants." Thesis, Link to the online version, 1995. http://hdl.handle.net/10019.1/1326.
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Setréus, Johan. "Development of a Simulation Module for the Reliability Computer Program RADPOW." Thesis, KTH, School of Electrical Engineering (EES), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4119.
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Detta examensarbete beskriver hur en Monte Carlo simulering (MCS) kan användas för tillförlitlighetsanalys av ett eldistributionssystem. Metoden har implementerats i verktyget RADPOW som nu kan utföra både analytiska och numeriska beräkningar. Angreppssättet för att utveckla denna MCS metod i RADPOW innefattade följande aktiviteter:
• Vidareutvecklade av RADPOW med införandet av ett grafiskt användargränssnitt för Windows.
• Utveckling och implementering av en iterativ analytisk metod för känslighetsanalys av eldistributionssystem i RADPOW.
• Utveckling och implementering av MCS metoden i RADPOW, vilken placerades i en fristående modul kallad Sim.
Den implementerade MCS metoden har validerats i en jämförande studie innefattande två testsystem med datorprogrammet NEPLAN. Resultat från denna studie visar att MCS metoden ger samma resultat som den analytiska metoden i RADPOW och det kommersiella verktyget NEPLAN.
This master thesis describes an implementation of a Monte Carlo Simulation (MCS) method for reliability assessment of electrical distribution systems. The method has been implemented in the reliability assessment tool RADPOW which now is able to perform both analytical and simulation evaluations. The main contributions within this thesis includes the following activities;
• Further development of RADPOW by the introducing of a graphical user interface for Windows.
• Development and implementation of an analytical sensitivity analysis routine for RADPOW.
• Development and implementation of a sequential MCS method in RADPOW in a stand alone module referred to as Sim.
The implemented MCS method has been validated in a comparable study for two case systems by a commercial software NEPLAN. Results shows that the implemented MCS method provides the same results as the analytical method in RADPOW and the NEPLAN software.
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Sun, Jian Reddy Agami T. Dr. "Methodology for adapting rigorous simulation programs to supervisory control of building HVAC & R systems: simulation, calibration and optimization /." Philadelphia, Pa. : Drexel University, 2004. http://dspace.library.drexel.edu/handle/1860/381.
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Ng, Kwok-kei Simon, and 吳國基. "Optimal planning and management of stochastic demand and renewable energy in smart power grid." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B50434299.
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To combat global climate change, the reduction of carbon emissions in different industries, particularly the power industry, has been gradually moving towards a low-carbon profile to alleviate any irreversible damage to the planet and our future generations. Traditional fossil-fuel-based generation is slowly replaced by more renewable energy generation while it can be harnessed. However, renewables such as solar and wind are stochastic in nature and difficult to predict accurately. With the increasing content of renewables, there is also an increasing challenge to the planning and operation of the grid.
With the rapid deployment of smart meters and advanced metering infrastructure (AMI), an emerging approach is to schedule controllable end-use devices to improve energy efficiency. Real-time pricing signals combined with this approach can potentially deliver more economic and environmental advantages compared with the existing common flat tariffs. Motivated by this, the thesis presents an automatic and optimal load scheduling framework to help balance intermittent renewables via the demand side.
A bi-level consumer-utility optimization model is proposed to take marginal price signals and wind power into account. The impact of wind uncertainty is formulated in three different ways, namely deterministic value, scenario analysis, and cumulative distributions function, to provide a comprehensive modeling of unpredictable wind energy. To solve the problem in off-the-shelf optimization software, the proposed non-linear bi-level model is converted into an equivalent single-level mixed integer linear programming problem using the Karush-Kuhn-Tucker optimality conditions and linearization techniques. Numerical examples show that the proposed model is able to achieve the dual goals of minimizing the consumer payment as well as improving system conditions. The ultimate goal of this work is to provide a tool for utilities to consider the demand response model into their market-clearing procedure.
As high penetration of distributed renewable energy resources are most likely applied to remote or stand-alone systems, planning such systems with uncertainties in both generation and demand sides is needed. As such, a three-level probabilistic sizing methodology is developed to obtain a practical sizing result for a stand-alone photovoltaic (PV) system. The first-level consists of three modules: 1) load demand, 2) renewable resources, and 3) system components, which comprise the fundamental elements of sizing the system. The second-level consists of various models, such as a Markov chain solar radiation model and a stochastic load simulator. The third-level combines reliability indices with an annualized cost of system to form a new objective function, which can simultaneously consider both system cost and reliability based on a chronological Monte Carlo simulation and particle swamp optimization approach. The simulation results are then tested and verified in a smart grid laboratory at the University of Hong Kong to demonstrate the feasibility of the proposed model.
In summary, this thesis has developed a comprehensive framework of demand response on variable end-use consumptions with stochastic generation from renewables while optimizing both reliability and cost. Smart grid technologies, such as renewables, microgrid, storage, load signature, and demand response, have been extensively studied and interactively modeled to provide more intelligent planning and management for the smart grid.published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy
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Uong, Hoang. "The application of the ordered list method and the dynamic programming to the unit commitment." PDXScholar, 1989. https://pdxscholar.library.pdx.edu/open_access_etds/3948.
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Chaillout, J. J. "De la simulation .... .... à la récupération." Habilitation à diriger des recherches, Université de Grenoble, 2007. http://tel.archives-ouvertes.fr/tel-00614924.
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Le " Chapitre II : De la simulation...." résume ma connaissance des principales méthodes numériques utilisées en électromagnétisme. Suit ensuite le résumé de mes études les plus représentatives dans le domaine de la simulation numérique en électromagnétisme : une en statique, une en quasi-statique avec couplage faible et une en propagation d'ondes. Souvent seule la méthode appliquée à des cas test est présentée, car leurs niveaux de confidentialité empêchent d'en présenter les résultats quantifiés. Le " Chapitre III :.... À la récuperation " contient tout d'abord un état de l'art de la récupération d'énergie permettant de comparer les performances des différents couples sources/conversion. Pour cela, j'insiste particulièrement sur tous les facteurs à prendre en compte pour choisir le couple optimal dans un environnement donné. Ensuite, on y trouve le résumé des deux thèses et d'un DRT que j'ai co-encadrés dans le domaine. Le " Chapitre IV : perspectives " présente les évolutions de ma carrière scientifique dans les deux axes développés dans ce rapport. Pour les évolutions souhaitables des méthodes numériques de manière générale et plus particulièrement dans mon Département, j'en expose ma vision et comment je prévois d'y contribuer. Pour l'axe énergétique, je présente les travaux prévus afin de conforter nos succès récents ainsi que les collaborations en cours ou amorcées.
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Twining, Erika. "Voltage compensation in weak distribution networks using shunt connected voltage source converters." Monash University, Dept. of Electrical and Computer Systems Engineering, 2004. http://arrow.monash.edu.au/hdl/1959.1/9701.
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Lalgudi, Subramanian N. "Transient simulation of power-supply noise in irregular on-chip power distribution networks using latency insertion method, and causal transient simulation of interconnects characterized by band-limited data and terminated by arbitrary terminations." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22561.
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Luwaca, Emmanuel. "Virtualization of a sensor node to enable the simulation of IEC 61850-based sampled value messages." Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/1179.
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Thesis submitted in fulfilment of the requirements for the degree
Master of Technology: Electrical Engineering
in the Faculty of Engineering
at the Cape Peninsula University of Technology
2014The IEC 61850 standard, “Communication networks and systems in substations” was promulgated to accommodate the need for a common communication platform within substations for devices from different vendors. The IEC 61850 standard proposes a substation automation architecture that is Ethernet-based, with a “station-bus” for protection devices within the substation and a “process bus” where raw data from the voltage and current transformers are published onto the data network using a device known as a Merging Unit. To date, most of the standardization efforts were focused at the station bus level where event-triggered messages are exchanged between the substation automation devices, commonly referred to as Intelligent Electronic Devices (IEDs). These messages are known as Generic Object Oriented Substation Event messages. Equipment from vendors to accommodate the “process bus” paradigm, however is still limited at present. The Centre for Substation Automation and Energy Management Systems was established within the Electrical Engineering Department at the Cape Peninsula University of Technology with one of its objectives being the development of equipment either for simulation or real-time purposes in compliance with the IEC 61850 standard. In order to fulfil this long-term objective of the Centre, an in-depth understanding of the IEC 61850 standard is required. This document details the efforts at acquiring the requisite knowledge base in support of the educational objectives of the Centre and the research project implements a simulation of a merging unit which is compliant with the functional behavior as stipulated by the standard. This limited functional implementation (i.e. non-real-time) of the merging unit, is achieved through the development of a virtualized data acquisition node capable of synthetic generation of waveforms, encoding of the data and publishing the data in a format compliant with the IEC 61850-9-2 sampled value message structure. This functional behavior of the virtual sensor node which was implemented has been validated against the behavior of a commercial device and the sampled value message structure is validated against the standard. The temporal behavior of the proposed device is commented upon. This research project forms the basis for future real-time implementation of a merging unit.
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Rader, Jordan D. "Loss of normal feedwater ATWS for Vogtle Electric Generating Plant using RETRAN-02." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31741.
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Thesis (M. S.)--Nuclear Engineering, Georgia Institute of Technology, 2010.Committee Chair: Abdel-Khalik, Said I.; Committee Member: Ghiaasiaan, S. Mostafa; Committee Member: Hertel, Nolan E. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Toscano, Andre Emilio. "Comparação entre os modelos NEWAVE e ODIN no planejamento energetico do Sistema Interligado Nacional." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259870.
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Orientador: Secundino Soares FilhoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
Made available in DSpace on 2018-08-13T19:42:40Z (GMT). No. of bitstreams: 1 Toscano_AndreEmilio_M.pdf: 30584461 bytes, checksum: 8f532daf632ae90c9325c899608a0457 (MD5) Previous issue date: 2009
Resumo: Os modelos de planejamento energético aplicados ao Sistema Interligado Nacional (SIN) devem fornecer um despacho de geração hidrotérmica que atenda ao mercado de energia elétrica brasileiro de forma a assegurar o atendimento das demandas e a minimizar os custos operativos. Devido às características hidrelétricas predominantes no sistema brasileiro, o planejamento visa determinar o despacho hidrelétrico otimizado que minimiza a complementação termelétrica necessária ao atendimento das demandas de energia elétrica do SIN. O modelo de planejamento energético de longo prazo em vigor no sistema elétrico brasileiro é o NEWAVE, um modelo estocástico que representa o sistema através de subsistemas equivalentes de energia e que tem sua solução desagregada a usinas individualizadas por outros modelos, como o DECOMP ou SUISHI-O. O modelo ODIN é a metodologia de planejamento energético desenvolvida na UNICAMP, que trata a estocasticidade das vazões afluentes de forma indireta, por meio de um previsor de vazões e de um otimizador a usinas individualizadas, e que a cada intervalo de planejamento fornece as decisões de despacho hidrotérmico por usina considerando as vazões previstas e a otimização da geração hidráulica do sistema. Este trabalho apresenta a comparação de desempenho entre os modelos de planejamento energético NEWAVE e ODIN na obtenção do despacho hidrotérmico otimizado para o SIN
Abstract: The optimization models applied to hydrothermal scheduling on the Brazilian National Interconnected System (SIN) shall provide the order of hydrothermal generation that meets the Brazilian market of electric energy in a way that the demands of power are attended and the operating costs, minimized. Due to the hydroelectric predominant feature in the Brazilian system, the planning aim to determine the optimal hydroelectric generation that minimizes the thermoelectric supplementation necessary to attend the power demands of Brazilian SIN. The long-term hydrothermal scheduling plan model operating nowadays in the Brazilian electrical system is the NEWAVE, a stochastic model that represents the system by equivalent subsystems of energy, through composite reservoirs, and has its solution decompounded of individualized plants by other models, like the DECOMP and SUISHI-O. The ODIN model is the energy planning methodology developed at UNICAMP that treats indirectly the stochasticity of affluent flows. This is done by means of an inflow predictor and an optimizer for individual plants, thats provide the planning decisions at each interval to order the hydrothermal scheduling considering the provided flow generation for each plant and the optimization of the hydraulic generation of the system. This work presents a comparison of performance between the models of hydrothermal scheduling NEWAVE and ODIN, in their obtainment of optimized hydrothermal scheduling for the Brazilian SIN
Mestrado
Energia Eletrica
Mestre em Engenharia Elétrica
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Gougeon, Ludivine. "Comparaison de schémas numériques pour la simulation d'écoulements turbulents réactifs." Phd thesis, Université d'Orléans, 2007. http://tel.archives-ouvertes.fr/tel-00282242.
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Ce travail de thèse porte sur le développement et la comparaison d'outils numériques pour la simulation d'écoulements compressibles réactifs turbulents. Les objectifs de cette étude sont doubles : il s'agit d'une part de tester l'approche de la Simulation des Grandes Échelles Implicite (MILES) et d'autre part de doter le laboratoire d'une plate-forme de simulation numérique performante, évolutive, robuste et précise. Pour cela, deux programmes d'approches et de portées différentes ont été élaborés.Le premier code, basé sur des schémas aux différences finies compactes centrées d'ordre 6, très précis et non dissipatifs, permet la simulation numérique directe (DNS) d'écoulements 3D turbulents sans chocs, en géométrie cartésienne. Ce code n'introduit pas de dissipation numérique et sert de référence pour tester l'approche MILES.
Le second code s'appuie sur l'utilisation de méthodes récentes à capture de chocs : les schémas WENO. La formulation aux différences finies des schémas WENO d'ordre 3 à 11 est implémentée dans un code bidimensionnel. Le pouvoir de résolution des schémas WENO des différents ordres est évalué par analyse linéaire. Les problèmes spécifiques au cas multi-espèces sont mis en évidence et la positivité des fractions massiques est respectée grâce à la méthode de Larrouturou. Les différentes reconstructions ainsi que l'ordre du schéma sont évalués sur une série de cas test.
Les deux codes font l'objet d'une comparaison sur la simulation d'une flamme 1D laminaire de prémélange et d'un jet 2D turbulent réactif H2/air. Enfin, les potentialités du schéma WENO sont démontrées sur une onde de détonation puis sur une interaction réactive onde de choc/bulle d'hydrogène.
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Yang, Fang. "A Comprehensive Approach for Bulk Power System Reliability Assessment." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14488.
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Abstract
The goal of this research is to advance the state of the art in bulk power system reliability assessment. Bulk power system reliability assessment is an important procedure at both power system planning and operating stages to assure reliable and acceptable electricity service to customers. With the increase in the complexity of modern power systems and advances in the power industry toward restructuring, the system models and algorithms of traditional reliability assessment techniques are becoming obsolete as they suffer from nonrealistic system models and slow convergence (even non-convergence) when multi-level contingencies are considered and the system is overstressed. To allow more rigor in system modeling and higher computational efficiency in reliability evaluation procedures, this research proposes an analytically-based security-constrained adequacy evaluation (SCAE) methodology that performs bulk power system reliability assessment.
The SCAE methodology adopts a single-phase quadratized power flow (SPQPF) model as a basis and encompasses three main steps: (1) critical contingency selection, (2) effects analysis, and (3) reliability index computations. In the critical contingency selection, an improved contingency selection method is developed using a wind-chime contingency enumeration scheme and a performance index approach based on the system state linearization technique, which can rank critical contingencies with high accuracy and efficiency. In the effects analysis for selected critical contingencies, a non-divergent optimal quadratized power flow (NDOQPF) algorithm is developed to (1) incorporate major system operating practices, security constraints, and remedial actions in a constrained optimization problem and (2) guarantee convergence and provide a solution under all conditions. This algorithm is also capable of efficiently solving the ISO/RTO operational mode in deregulated power systems. Based on the results of the effects analysis, reliability indices that provide a quantitative indication of the system reliability level are computed. In addition, this research extends the proposed SCAE framework to include the effects of protection system hidden failures on bulk power system reliability.
The overall SCAE methodology is implemented and applied to IEEE reliability test systems, and evaluation results demonstrate the expected features of proposed advanced techniques. Finally, the contributions of this research are summarized and recommendations for future research are proposed.
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Derakhshanian, Mahin. "Simulations numériques des vibrations induites par effet de couronne sur un court conducteur soumis à une pluie artificielle /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2001. http://theses.uqac.ca.
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Kuk, Josiel Neumann. "Um sistema imune fuzzy cultural aplicado ao problema de despacho econômico de energia elétrica." Universidade Tecnológica Federal do Paraná, 2009. http://repositorio.utfpr.edu.br/jspui/handle/1/1335.
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CAPESEste trabalho tem como objetivo principal a proposição de um sistema híbrido baseado em Computação Natural que seja capaz de solucionar, de forma eficiente, diferentes instâncias do problema de Despacho Econômico de Energia Elétrica com efeito de ponto de válvula. Para isso está sendo proposta uma abordagem baseada em um Algoritmo Cultural, o qual tem como espaço populacional um Algoritmo Imunológico Artificial. No espaço de crenças são utilizados quatro tipos de conhecimentos: situacional, normativo, topográfico e histórico. Nos protocolos de comunicação, a função de aceitação e dinâmica e a função de influência e baseada em um Sistema de Inferência Fuzzy, o qual define o possível percentual de aplicação de cada um dos conhecimentos. Para avaliar o paradigma proposto são utilizadas três instâncias do problema do Despacho Econômico de Energia Elétrica. Os resultados mostram que a introdução de um Sistema de Inferência Fuzzy, auxiliando a decisão do tipo de conhecimento a ser aplicado, pode trazer benefícios nos resultados. Na comparação com os resultados reportados na literatura, observa-se que a abordagem, apesar de não ter seus parâmetros otimizados para cada caso, e competitiva com os algoritmos do estado-da-arte.
The main objective of this work is the proposal of a hybrid system based on Natural Computing approaches, which is capable of efficiently solving different instances of the Economic Load Dispatch problem of electrical energy with valve-point effect. For this purpose it is developed a new approach based on Cultural Algorithm, which has as its population space an Artificial Immune System. In the belief space, we use four knowledge types: situational, normative, topographical and historical. In the communication protocols, the acceptance function is dynamic and the principal influence function is based on a Fuzzy Inference System which defines the probable percentage of application of each knowledge type. Three instances of the Economic Load Dispatch with Non-smooth Cost Functions problem are used to evaluate the proposed paradigm. The results show that the introduction of fuzzy systems to support the decision of which type of knowledge must be applied can bring benefits to the obtained results. Although its parameters were not optimized for each case of study, the proposed algorithm performed likewise the state-of-the-art algorithms.
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Volat, Christophe. "Modélisation physique et numérique par la méthode des éléments finis de frontière de la distribution du potentiel et du champ électrique le long d'un isolateur standard de poste 735 KV recouvert de glace /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2002. http://theses.uqac.ca.
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Venturi, Elisa. "Dynamic simulation and analysis of a Passive House case study with direct PV system for heating and domestic hot water production." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16590/.
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Different heating systems for space heating and domestic hot water (DHW) preparation are investigated with respect to their energy efficiency. In particular, a case study of a multi-storey Passive House (called An-der-Lan) is analysed by means of dynamic simulations.
The first part of dynamic simulations focuses on the comparison of the UA and RC models for a simple office located in Rome. This is a case study from the project IEA SHC T56 – System Simulation Models. In particular, attention is put on the influence of the thermal capacity. Assuming the RC model as the reference case, variants of the UA model with different percentages of the thermal capacity are simulated, in order to find out the most similar to the RC model. The same investigation is carried out for the An-der-Lan building. In general, it is not possible to identify the best UA model, because for every considered quantity, the minimum difference between the UA and RC model is got for a different percentage of the thermal mass.
The second part of dynamic simulation focuses on the comparison among different systems for heating and DHW preparation. The realized system is direct electric heating for both space heating and DHW preparation. It is denoted as the reference Case1 and it is compared against alternative solutions. Case2 is based on a central air/water heat pump system for both heating and DHW production. A sensitivity analysis study is conducted. Finally, Case3 and Case4 are a mix of the previous two cases.
Results show that Case2 is the best in terms of electric energy required from the grid, although it is the system with the highest thermal losses. Furthermore, the PV system only in the south façade is not sufficient to cover the energy required in neither of the cases.
Finally, annual, monthly, daily, hourly and 10 minutes balances are compared. Results show the importance of smaller time step in balances between required and produced energy, in order to have more precise results.
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Libéros, Véronique. "Etablissement automatique de schémas équivalents pour des dispositifs de puissance intégrés." Toulouse, INSA, 1989. http://www.theses.fr/1989ISAT0035.
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Il s'agit d'un outil logiciel d'aide a la conception. En considerant les etapes technologiques de realisation de structure integrees, une liste des primitives physiques est dressee, ainsi que celle des primitives electriques associees permettant de decrire le fonctionnement electrique reel des dispositifs. Description du logiciel. Exemples choisis dont thyristor a gachette isolee et inverseur cmos
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Bodèle, Emmanuel. "Modélisation et simulation de l'atomisation secondaire et de la vaporisation turbulente : application à la combustion cryotechnique." Phd thesis, Université d'Orléans, 2004. http://tel.archives-ouvertes.fr/tel-00283103.
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Ce travail se situant dans le cadre du Groupement de Recherche « Combustion dans les moteurs-fusées » unissant le CNES, le CNRS, l'ONÉRA et la SNECMA concerne l'étude de l'atomisation secondaire et de la vaporisation turbulente pour la combustion des brouillards. L'objectif principal de cette étude est de fournir des modèles fiables pour les codes de calcul, reproduisant fidèlement les processus élémentaires de la combustion cryogénique dans les moteurs-fusées.Ces modèles sont issus d'études expérimentales précédentes du LCSR, ayant permis d'établir des bases de données.
Les calculs sont basés sur la simulation du banc d'essai MASCOTTE (Montage Autonome Simplifié pour la Cryocombustion dans l'Oxygène et Toutes Techniques Expérimentales) de l'ONERA. Les résultats montrent d'une part l'influence de l'atomisation sur la structure du brouillard et de la flamme. D'autre part, les simulations de la vaporisation turbulente mettent en évidence l'influence de la turbulence sur les propriétés des gouttes.
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Chen, Si. "Design of Energy Storage Controls Using Genetic Algorithms for Stochastic Problems." UKnowledge, 2015. http://uknowledge.uky.edu/ece_etds/80.
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A successful power system in military applications (warship, aircraft, armored vehicle etc.) must operate acceptably under a wide range of conditions involving different loading configurations; it must maintain war fighting ability and recover quickly and stably after being damaged. The introduction of energy storage for the power system of an electric warship integrated engineering plant (IEP) may increase the availability and survivability of the electrical power under these conditions. Herein, the problem of energy storage control is addressed in terms of maximizing the average performance. A notional medium-voltage dc system is used as the system model in the study. A linear programming model is used to simulate the power system, and two sets of states, mission states and damage states, are formulated to simulate the stochastic scenarios with which the IEP may be confronted. A genetic algorithm is applied to the design of IEP to find optimized energy storage control parameters. By using this algorithm, the maximum average performance of power system is found.
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Dubos, Samuel. "SIMULATION DES GRANDES ECHELLES D'ECOULEMENTS TURBULENTS SUPERSONIQUES." Phd thesis, INSA de Rouen, 2005. http://tel.archives-ouvertes.fr/tel-00011588.
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Ces travaux, initiés par le CNES et la SNECMA, sont principalement consacrés à la simulation numérique d'écoulements turbulents supersoniques en présence d'interactions ondes de choc/couche limite. L'étude de ces écoulements, sièges de phénomènes complexes, se révèle être d'une importance particulière en vue du dimensionnement d'organes de propulsion de lanceurs spatiaux. Il a été choisi, dans ce travail, d'investir les aspects instationnaires au moyen de la simulation des grandes échelles turbulentes. Les contraintes liées au traitement numérique ont aboutit au développement d'un schéma numérique hybride, permettant de minimiser les effets de dissipation inhérents aux schémas dédiés à la capture de chocs. Le problème de la génération de conditions aux limites turbulentes réalistes est également abordé. Une technique due à Lund, fondée sur un principe de renormalisation et permettant à l'écoulement de générer lui-même ses conditions d'entrée, a été retenue. Les résultats des simulations se sont révélées être en très bon accord avec les mesures expérimentales ainsi qu'avec les DNS de référence. En particulier, l'existence de basses fréquences associées au mouvement du choc réfléchi a pu être constatée, en accord avec les observations expérimentales. De plus, la simulation a révélé la présence de fréquences similaires à l'intérieur du bulbe de recirculation, venant ainsi conforter l'hypothèse selon laquelle les instabilités du choc de décollement sont conditionnées par celles de la zone décollée.
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Blin, Laurent. "Modélisation statistique et simulation des grandes échelles des écoulements turbulents. Application aux inverseurs de poussée." Phd thesis, Université de Rouen, 1999. http://tel.archives-ouvertes.fr/tel-00011645.
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Ce travail de thèse a été consacré au développement d'outils numériques pour aider à la compréhension, par simulation numérique, de l'aérodynamique d'un inverseur de poussée à portes (écoulement turbulent compressible). Dans cette étude, nous avons adopté deux approches complémentaires : résolution des équations de Navier-Stokes moyennées RANS (stationnaires) ou filtrées LES (instationnaires). Dans un premier temps, les divers phénomènes physiques présents dans un inverseur de poussée sont décomposés et étudiés séparément. On simule ainsi successivement :(1) un écoulement décollé (marche descendante - calcul RANS),
(2) un écoulement cisaillé libre (couche de mélange plane - calculs RANS et LES),
(3) des écoulements présentant de fortes courbures des lignes de courant (conduite rectangulaire courbée (calcul RANS) et couche de mélange courbe - calculs RANS et LES). Ensuite, deux configurations simplifiées d'inverseurs de poussée à portes sont étudiées numériquement par simulations RANS et LES.
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LEHNASCH, Guillaume. "Contribution à l'étude numérique des jets supersoniques sous-détendus." Phd thesis, Université de Poitiers, 2005. http://tel.archives-ouvertes.fr/tel-00010669.
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Cette étude est inspirée en particulier par le besoin, lors de la phase d'intégration d'un moteur aéronautique, de maîtriser a priori les risques d'endommagements liés à la possible décharge d'un écoulement de gaz brûlés à haute pression et haute température, issu d'un orifice apparaissant accidentellement au niveau de la paroi de la chambre de combustion. Après avoir brossé un tableau exhaustif de la phénoménologie des écoulements considérés, une stratégie est proposée afin de surmonter les difficultés numériques particulières associées à la simulation de tels jets, et d'obtenir des solutions stationnaires pour un rapport coût / précision raisonnable. La procédure retenue repose sur l'utilisation i) d'une méthode mixte volumes finis / éléments finis pour intégrer la formulation axisymétrique des équations de Navier-Stokes en régime compressible, ii) de schémas décentrés (TVD) pour évaluer les flux convectifs, iii) d'une méthode de réadaptation anisotrope de maillages non-structurés et iv) d'un modèle de turbulence k-ε modifié afin de réintégrer les principaux effets de compressibilité. L'analyse des résultats obtenus démontre que la stratégie retenue nous permet de prévoir correctement la structure d'ensemble des différents jets considérés et confirme que celle-ci est très sensible aux conditions d'entrée prévalant au niveau de l'orifice, ce qui nous conduit d'ores et déjà à préconiser une évolution de la définition des tests de certification.
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Cannevière, Karine. "Simulation Numérique Directe de la combustion turbulente diphasique: Application à l'étude de la propagation et de la structure des flammes." Phd thesis, INSA de Rouen, 2003. http://tel.archives-ouvertes.fr/tel-00006820.
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Ce travail est consacré à l'étude de la propagation et de la structure des flammes dans le cas des écoulements turbulents diphasiques. Pour cela, un code de simulation numérique directe (DNS) est utilisé. Les équations et le modèle chimique employés dans le code de DNS sont tout d'abord présentés. Ensuite, une étude des flammes diphasiques laminaires est réalisée. Dans un premier temps, une étude analytique portant sur la dynamique d'évaporation des gouttes est proposée. L'influence importante sur le mode de combustion du rapport entre le temps de préchauffage de la goutte et le temps d'évaporation, est mise en évidence. La simulation de la propagation d'une flamme au sein d'un nuage de gouttes est réalisée et un comportement de flamme pulsée est abordée. Une étude de ces flammes en fonction de la topologie du combustible liquide nous a permis de montrer qu'elles avaient une structure de flamme double composée d'une flamme de prémélange suivie d'une flamme de diffusion. L'étude des flammes turbulentes diphasiques fait l'objet de notre dernière étude. Des DNS de l'injection de sprays monodisperses sont effectuées en variant les paramètres d'injection de la phase liquide (densité, rapport d'équivalence). La base de données obtenue nous permet de décrire les régimes de flamme locaux et globaux apparaissant dans la combustion de sprays, et qui sont répertoriés en quatre familles principales : régime externe ouvert et fermé, combustion de groupe et combustion mixte. Enfin, un diagramme de combustion est développé, impliquant le temps d'évaporation des gouttes, la distance inter-gouttes ou inter-groupes de gouttes, et enfin le rapport d'équivalence injecté.
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Hlioui, Sami. "Etude d'une machine synchrone à double excitation Contribution à la mise en place d'une plate-forme de logiciels en vue d'un dimensionnement optimal." Phd thesis, Université de Technologie de Belfort-Montbeliard, 2008. http://tel.archives-ouvertes.fr/tel-00344568.
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Dans le cadre de la motorisation électrique des véhicules dits « propres » (tels que les véhicules hybrides) où le cahier des charges est difficile à satisfaire, une dizaine d'équipes dans le monde prospectent des topologies de machines synchrones qui permettraient de combiner la souplesse de fonctionnement de la machine synchrone à excitation bobinée aux avantages de la machine synchrone à aimants permanents.Parmi ces structures, nous trouvons la Machine Synchrone à Aimants Permanents à Concentration de Flux et à Double Excitation (MSAPConFDE) qui fait l'objet des travaux de recherche présentés dans cette thèse réalisée dans le cadre d'une coopération interuniversitaire entre le laboratoire SET de l'Université de Technologie de Belfort-Montbéliard et le laboratoire SATIE de l'Ecole Normale Supérieure de Cachan. On s'est intéressé, en premier lieu, à l'étude par la méthode des éléments finis de cette structure. Les modèles prennent en compte l'aspect tridimensionnel de la MSAPConFDE, l'anisotropie du feuilletage et la saturation magnétique. Ils ont permis d'approfondir la compréhension des phénomènes qui régissent le fonctionnement d'une telle structure et d'analyser les différents trajets de flux. En second lieu, des modèles analytiques, basés sur la méthode des schémas réluctants, ont été établis. Les trajets de flux tridimensionnels, la saturation magnétique et les différents trajets de fuites ont été pris en compte. Finalement, ces modèles ont été exploités dans une démarche de pré-dimensionnement optimal basée sur l'algorithme génétique. Les résultats obtenus nous encouragent à enrichir l'outil de pré-dimensionnement par de nouveaux modèles de machines synchrones et par différents algorithmes d'optimisation. Ceci permettra d'aboutir vers une plate-forme de logiciels pour le pré-dimensionnement optimal des machines synchrones pour un cahier des charges donné.
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Gillon, frédéric. "MODELISATION ET OPTIMISATION PAR PLANS D'EXPERIENCES D'UN MOTEUR A COMMUTATIONS ELECTRONIQUES." Phd thesis, Université des Sciences et Technologie de Lille - Lille I, 1997. http://tel.archives-ouvertes.fr/tel-00006014.
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Les machines BDC (Brushless Direct Current) apportent une solution intéressante pour la réalisation de ventilateurs industriels à courant continu. Ces machines présentent deux avantages décisifs : d'une part elles possèdent une durée de vie élevée, et d'autre part permettent l'ajout de nouvelles fonctionnalités grâce à l'utilisation de composants électroniques. Dans un premier temps, les principaux phénomènes agissant sur le fonctionnement de ces machines sont étudiés à partir de quelques formules analytiques simples. Ensuite, une modélisation plus fine mais également plus globale est réalisée à l'aide de la méthode des éléments finis. Tout d'abord, une modélisation tridimensionnelle statique met en évidence un phénomène bénéfique de concentration de flux au sein du stator. Ceci nous amène à définir un coefficient de concentration qui sera étudié en détails pour toute une gamme de moteurs. A partir de ces résultats, une modélisation éléments finis dynamique bidimensionnelle incluant un couplage magnétique, électrique, mécanique est réalisée afin d'obtenir un modèle fiable, robuste et malléable, soit un véritable prototype virtuel. Un tel modèle est absolument indispensable pour aborder toute optimisation significative. De plus, les effets tridimensionnels sont intégrés dans ce modèle plan par l'intermédiaire du coefficient de concentration précédemment établi. La méthode des plans d'expériences est présentée comme un outil d'aide à la conception et à l'optimisation. Cette méthode consiste à organiser la démarche expérimentale et l'analyse décisionnelle en appliquant des règles rigoureuses basées sur l'exploitation des propriétés algébriques et statistiques des matrices décrivant les expériences. En définitive, une démarche basée sur l'utilisation de la méthode des plans d'expériences est proposée pour aborder les problèmes d'optimisation. Une recherche des seuls paramètres influents est faite par l'intermédiaire des plans fractionnaires afin que seuls les facteurs les plus influents soient gardés lors de l'optimisation. Puis, une méthode directe d'optimisation par plans d'expériences successifs a été testée et comparée avec d'autres méthodes d'optimisation plus classiques. Grâce à ce travail, Etri a pu acquérir certaines compétences dans les machines BDC et réaliser de nouveaux produits.
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Green, Robert C. II. "Novel Computational Methods for the Reliability Evaluation of Composite Power Systems using Computational Intelligence and High Performance Computing Techniques." University of Toledo / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1338894641.
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