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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Feasibility Study of Vehicular Teleoperation over Cellular Network in Urban Scenario / Genomförbarhet studie av teleoperation av fordon via mobilnätverk i stadsscenario

Jin, Yifei January 2017 (has links)
With the continuous progress on autonomous vehicle and remote drivingtechniques, connection quality demands are changing compared withconventional quality of service. Vehicle to everything communication, asthe connectivity basis for these applications, has been built up on LongTerm Evolution basis, but due to various ethical and environmental issues,few implementations have been made in reality. Therefore simulation approachesare believed to provide valuable insights.To fully model an LTE vehicular network, in this work we first providea comparison study to select the preferable LTE simulator. Aimingto integrate communication nodes with mobility, a solution for simulationframework is developed based on a state-of-art comparison study on theexisting simulator frameworks. We then further develop the network simulator,and complement it with hybrid wireless channel modeling, channeland quality of service aware scheduler, and admission control strategies. Interms of instant optimization of the network, real-time access is emulatedfor external devices to communicate with the simulator. In this thesis,the evaluation of the framework performance considers two aspects: theperformance of the simulator in LTE V2X use case and the feasibility ofthe service, specifically, remote driving, under realistic network capacity.For our framework, the results indicate that it is feasible to realize remotedriving in an LTE urban scenario, but, as an example, we show that foran area of Kista, five vehicles could be hold by a base-station with guaranteedservice at most. / Med kontinuerliga framstegen p°a autonomt fordon och fj¨arrkontrollteknikf¨or¨andras kravet p°a anslutningskvalitet i j¨amf¨orelse med konventionell servicekvalitet.Fordon till allting (V2X) kommunikation, som anslutningsgrundf¨or dessa applikationer, har byggts upp p°a basis av Long TermEvolution (LTE) system, men p°a grund av olika etiska och milj¨om¨assigaproblem har f°a implementeringar gjorts i verkligheten. D¨arf¨or antas simuleringsmetoderge v¨ardefulla insikter.Att fullt ut modellera ett LTE-fordon n¨atverk, i det h¨ar arbetet ger vif¨orst en j¨amf¨orelsestudie f¨or att v¨alja den f¨oredragna LTE-simulatorn.I syfte att integrera kommunikationsnoder med r¨orlighet utvecklas enl¨osning f¨or ett simuleringsramverk baserat p°a en j¨amf¨orelsestudie p°a befintligasimulatorramar. Vi utvecklar sedan n¨atverkssimulatorn ytterligare,och kompletterar den med hybrid tr°adl¨os kanalmodellering, kanal ochservicekvalitetmedvetna schemal¨aggning och antagningskontrollstrategier.N¨ar det g¨aller direkt n¨atverksoptimering, emuleras realtidsanslutningav externa enheter f¨or att kommunicera med simulatorn. I denna avhandlingutv¨arderas ramverken i tv°a aspekter: simulatorns prestanda i LTEV2X-anv¨andningsomr°adet och genomf¨orbarheten av tj¨ansten, s¨arskilt fj¨arrk¨orning,under realistisk n¨atkapacitet. In v°ara ramverk visar resultaten att det ¨arm¨ojligt att realisera fj¨arrk¨orning i ett LTE-urbana scenario, men som exempelvisar vi att f¨or ett omr°ade i Kista skulle som mest fem fordon kunnask¨otas av en basstation med garanterad service.
62

Comparing soft body simulations using extended position-based dynamics and shape matching

Westergren, Erik January 2022 (has links)
Today, soft body simulations are essential for a wide range of applications. They are for instance used for medical training in virtual reality and in video games to simulate clothes and hair. These kinds of interactive applications rely on real-time simulations, which entails very strict requirements. The simulation has to be fast enough and must never break, regardless of what deformation might occur. Two methods that perform well with regard to these requirements are the position-based dynamics (PBD) method and the shape matching method. Even though these methods have been used for years, it is still unclear when you should use either method. This thesis has compared the two methods with regard to the mentioned requirements. More specifically, the thesis has evaluated the performance of the simulation loop as well as the simulated objects’ ability to restore their shape after deformation. The performance results clearly show that the PBD method is the fastest. But the results of the simulated objects’ ability to restore their shape were not as conclusive. Overall, the PBD method seemed to perform the best again, but there were cases the method could not handle. Although the shape matching method performed slightly worse, it did manage to restore the shape of every deformed object. In conclusion, for most applications, the PBD method is likely the better option, but if the application relies on the fact that simulated objects can restore their shape, then the shape matching method may be preferable. / Idag är simulering av mjuka kroppar viktiga för en mängd olika tillämpningar. De används exempelvis för medicinsk träning i virtuell verklighet och i datorspel för att simulera kläder och hår. Dessa typer av interaktiva applikationer förlitar sig på realtidssimuleringar, vilket medför många stränga krav. Simuleringen måste vara tillräckligt snabb och får aldrig gå sönder, oavsett vad för slags deformation som kan uppstå. Två metoder som presterar bra med avseende på dessa krav är position-based dynamics (PBD) och shape matching. Trots att dessa metoder har använts i många år, så är det fortfarande oklart när vilken metod är mest lämplig. Denna avhandling har jämfört de två metoderna med hänsyn till de nämnda kraven. Mer specifikt har avhandlingen utvärderat metodernas prestanda samt de simulerade objektens förmåga att återställa sin form efter deformation. Resultaten för prestanda visar tydligt att PBD-metoden är snabbast. Men resultaten av de simulerade objektens förmåga att återställa sin form var inte lika enhälliga. Sammantaget verkade PBD-metoden prestera bäst igen, däremot fanns det fall som metoden inte kunde hantera. Fastän shape matching metoden presterade något sämre, så lyckades den återställa formen för varje deformerat objekt. Sammanfattningsvis, för de flesta applikationer är PBD-metoden troligen det bättre alternativet, men om applikationen förlitar sig på att de simulerade objekten kan återställa sina former, så kan shape matching metoden vara att föredra.
63

Development of Hybridization concept for horizontal axis wind / tidal systems using functional similarities and advanced real-time emulation methods / Développement de concepts d'hybridation pour les systèmes éoliens / hydroliens à axe horizontal utilisant des similitudes fonctionnelles et méthodes d'émulation avancées en temps réel

Ashglaf, Mohmed Omran 26 June 2019 (has links)
La capacité des systèmes conventionnels de production d'énergie éolienne et marémotrice à fournir au réseau une énergie fiable et stable à tout moment est un nouveau défi en raison des fluctuations météorologiques, qui ont un impact significatif et direct sur la production d'énergie. C'est pourquoi l'hybridation des systèmes de production d'énergie éolienne et hydrolienne ont été étudiées pour améliorer l'intégration des énergies éolienne et marémotrice sur le réseau électrique.Cette étude nous a amené à développer des contributions liées à deux axes principaux :Le premier axe est focalisé sur un nouveau concept d'hybridation de deux sources énergétiques différentes en termes de propriétés physiques, l’éolien et l’hydrolienne à axe horizontal, basé sur un couplage électromécanique de ces deux systèmes. Les deux ressources sont l’énergie éolienne et l’énergie des courants marins. Le concept est développé en utilisant les similitudes fonctionnelles des turbines et les similarités en conversion d’énergie de leurs chaînes énergétiques. Pour appliquer ce concept en premier lieu, les paramètres de la génératrice asynchrone à double alimentation installée dans l’émulateur du GREAH sont identifiés. Ensuite, la chaîne de conversion de puissance est modélisée mathématiquement et simulée dans un environnement MATLAB / SIMULINK. Nous avons développé deux stratégies de commande.Une stratégie à vitesse fixe appelé "Contrôle direct de la vitesse", et une stratégie à vitesse variable basée sur la recherche de puissance maximale, dénommée "Contrôle indirecte de vitesse". Enfin, ce concept a été implémenté pratiquement sur l’émulateur en temps réel du laboratoire. Les résultats obtenus ont été analysés et discutés suite à ces travaux.Le deuxième axe est consacré à un concept que l’on appelle «temps accélérée» de simulation ou « temps virtuel ». Par la suite, ce concept a été mis en œuvre sur l’émulateur multi physique disponible au laboratoire GREAH. Ce concept (temps accélérée) est basé sur la réduction des échantillons de profil de vent afin de diminuer le temps de simulation et faciliter la commande en temps réel.Les résultats principaux sont obtenus d’abord dans MATLAB / SIMULINK, puis ont été vérifiés sur l’émulateur en temps réel. L’objectif principal de cette thèse est d’étudier le concept d’hybridation éolienne offshore / éolienne basée sur la flexibilité d’un émulateur multifonctions permettant diverses architectures d’émulation : éoliennes, éoliennes, et systèmes hybrides éoliennes - éoliennes. Nous analysons son impact sur la puissance de sortie du système. Les résultats obtenus sont corrélés aux profils de vitesse du vent et des marées, dans lesquels les propriétés statistiques ayant un impact sur les chaînes énergétiques mondiales pourraient être complémentaires et en particulier en fonction des sites donnés.Contributions principales et perspectives- Développement du concept de couplage électromécanique. Lorsque deux sources d’énergie renouvelables sont « intégrées », on stabilise la fluctuation rapide de la puissance générée, mais sous certaines conditions telles que la présence d’unités de stockage ou d’un système d’embrayage automatique.- Le concept temps accéléréeCette méthode est utilisée pour réduire la taille des données enregistrées du vent ou des courant marins, afin d’accélérer le temps de simulation des unités de production d'énergie avec des résultats raisonnables qui se rapprochent pertinemment des situations réelles.- Etudier et développer le concept de régime d’arbre électrique :Si le couplage électromécanique est difficile à réaliser du point de vue mécanique et que les découplages à arbre unique sont trop fréquents et que les contraintes mécaniques sont élevées, on peut étudier le régime de l'arbre électrique avec deux machines à induction DFIG. Le système peut fonctionner en mode synchrone avec des structures et configurations spécifiques. / The ability of conventional wind and tidal generation systems to provide the grid with reliable and stable power at all times is a new challenge due to weather fluctuations, which have a significant and direct impact on energy production. This is why the hybridization of wind and tidal power generation systems has been studied to improve the integration of wind and tidal power into the electricity grid.This study led us to develop contributions related to two main axes:The first axis is focused on a new concept of hybridization of two different energy sources in terms of physical properties, wind and horizontal axis turbines, based on an electromechanical coupling of these two systems. The two resources are wind energy and marine energy. The concept is developed using the functional similarities of turbines and similarities in energy conversion of their energy chains. To apply this concept first, the parameters of the double fed asynchronous generator installed in the GREAH emulator are identified. Then, the power conversion chain is modeled mathematically and simulated in a MATLAB / SIMULINK environment. We have developed two control strategies.A fixed speed strategy called "Direct Speed Control", and a variable speed strategy based on the search for maximum power, called "Indirect Speed Control". Finally, this concept has been implemented practically on the real-time emulator of the laboratory. The results obtained were analyzed and discussed following this work.The second axis is devoted to a concept called "accelerated time" simulation or "virtual time". Subsequently, this concept was implemented on the multi-physics emulator available at the GREAH laboratory. This concept (accelerated time) is based on reducing wind profile samples in order to decrease simulation time and facilitate real-time control.The main results are obtained first in MATLAB / SIMULINK, then verified on the emulator in real time.The main objective of this thesis is to study the concept of offshore wind / tidal turbine hybridization based on the flexibility of a multi-function emulator that allows various emulation architectures: wind turbines, tidal turbines, and hybrid wind - tidal turbines systems. We analyze its impact on the output power of the system; the obtained results are correlated with wind and tidal speed profiles, in which statistical properties impacting global power chains could be complementary and in particular in function of the given sites. Main contributions and perspectives- Development of the concept of electromechanical coupling.When two renewable energy sources are "integrated", the rapid fluctuation of the power generated is stabilized, but under certain conditions such as the presence of storage units or an automatic clutch system.- The accelerated time conceptThis method is used to reduce the size of the recorded wind or sea current data, to speed up the simulation time of the power generation units with reasonable results that are close to actual situations.- Study and develop the concept of electric shaft regime: If the electromechanical coupling is difficult to achieve from the mechanical point of view and the single shaft decouples are too frequent so high mechanical stress, one can study the electric shaft regime with two DFIG induction machines.There is a regime in which the ratios between the speeds of the different machines are rigorously constant. The system can operate in synchronous mode with specific structures and configurations.
64

Proteção digital de geradores eólicos com conversores de potência de escala completa no contexto das smart grids / Digital protection of wind generators with full- scale power converter in the smart grid context

Bataglioli, Rodrigo Pavanello 02 July 2018 (has links)
Considerando condições anormais que o Sistema Elétrico de Potência (SEP) está sujeito, a proteção de seus elementos é um tópico importante. Dentre os equipamentos a serem protegidos, destacam-se os geradores devido a representarem elevado custo de investimento e estarem sujeitos a multas por paradas não programadas. Desta forma, com base em pesquisa bibliográfica, observa-se que não existem estudos abrangentes para a proteção individual de máquinas síncronas aplicadas à geração eólica. Além disso, considerando o contexto das smart grids, a presença de baterias e a possibilidade da operação ilhada podem alterar a dinâmica das situações de falta. Portanto, faz-se necessário um estudo do comportamento dos aerogeradores em situações de falha, sabendo que o esquema de proteção depende do tipo de gerador e da maneira como este está conectado ao SEP. Neste sentido, esta pesquisa propôs incluir uma bateria para operar com um gerador eólico de velocidade variável de forma complementar, suavizando a potência de saída e tornando o sistema de conversão de energia eólica forte o suficiente para operar no modo ilhado. A metodologia estabelece vários tipos de falhas para investigar o comportamento da turbina eólica em tais condições. Para realizar as simulações de falta, foi utilizado um simulador digital de tempo real (RTDS®). Com base nisso, um esquema composto por funções de proteção convencionais foi especificado e testado usando o software MATLAB®. Além disso, simulações em laço fechado foram realizadas com relés comercial e universal. Os resultados obtidos com o esquema proposto são bastante promissores. / Considering abnormal conditions to which the Electric Power System (EPS) may be subjected, the protection of its elements is an important topic. Among the equipments to be protected, the generators are highlighted, because they represent a high investment cost and are subjected to penalties for unscheduled stoppages. Hence, based on literature, it is observed that there are no comprehensive studies and standards for individual protection of Synchronous Generators (SGs) applied to Wind Energy Conversion System (WECS). Furthermore, considering the smart grids context, the presence of batteries and the possibility of island operation may change the dynamic of fault situations. Therefore, it is necessary to study and analyse the behavior of wind turbines in fault situations, knowing that the protection scheme is dependent on the generator type and the way it is connected to the EPS. In order to study these issues, this research proposed to include a battery to operate with a full-variable speed wind generator in a complementary way, smoothing the output power and making the WECS strong enough to operate in the island mode. The methodology establishes several fault types to investigate the wind turbine behavior in such conditions. In order to conduct the fault simulations, a real time digital simulator (RTDS®) was used. Based on this, a scheme composed by conventional protection functions were specified and tested using the MATLAB® software. Furthermore, hardware-in-the-loop simulations were performed with commercial and universal relays. Very good results in favor of the proposed scheme are presented.
65

Simulation temps réel de dispositifs électrotechniques / Real-time simulation of electrical power plant

Rakotozafy, Andriamaharavo 15 May 2014 (has links)
Les contrôleurs industriels font l’objet de changements de paramètres, de modifications, d’améliorations en permanence. Ils subissent les évolutions technologiques aussi bien matérielles que logicielles (librairies, système d’exploitation, loi de commande...). Malgré ces contraintes, ces contrôleurs doivent obligatoirement assurer toutes les fonctionnalités recouvrant le séquentiel, les protections, l’interface homme machine et la stabilité du système à contrôler. Ces fonctionnalités doivent être couvertes pour une large gamme d’applications. Chaque modification (matérielle ou logicielle) quoique mineure est risquée. Le debogage, l’analyse et la programmation sur site sont énormément coûteux surtout pour des sites de type offshore ou marine. Les conditions de travail sont difficiles et les tests sont réduits au strict minimum. Cette thèse propose deux niveaux de validation en plateforme d’expérimentation : un niveau de validation algorithmique que l’on appelle Validation par Interface Logicielle (VIL) traitée au chapitre 2 ; un niveau de validation physique que l’on appelle Validation par Interface Matérielle (VIM) traitée au chapitre 3. La VIL valide uniquement l’aspect algorithme, la loi de commande et la conformité des références au niveau calcul sans prendre en compte les signaux de commande physiques et les signaux de retour gérés par l’Unité de Gestion des Entrées/Sorties (UGES). Un exemple de validation d’un contrôleur industriel d’un ensemble convertisseur trois niveaux et machine asynchrone est traité dans le deuxième chapitre avec une modélisation particulièrement adaptée à la VIL. Le dernier chapitre traite la VIM sur différentes bases matérielles (Field Programmable Gate Array (FPGA), processeurs). Cette validation prend en compte l’aspect algorithme et les signaux de commande physique ainsi que les signaux de retour. On y présente plusieurs approches de modélisation, choisies selon la base matérielle d’implémentation du simulateur temps réel. Ces travaux ont contribué aujourd’hui à au processus de validation des contrôleurs dédiés aux applications Oil and Gaz et Marine de General Electric - Power Conversion © (GE-PC) / Industrial controllers are always subjected to parameters change, modifications and permanent improvements. They have to follow off-the-shelf technologies as well as hardware than software (libraries, operating system, control regulations ...). Apart from these primary necessities, additional aspects concerning the system operation that includes sequential, protections, human machine interface and system stability have to be implemented and interfaced correctly. In addition, these functions should be generically structured to be used in common for wide range of applications. All modifications (hardware or software) even slight ones are risky. In the absence of a prior validation system, these modifications are potentially a source of system instability or damage. On-site debugging and modification are not only extremely expensive but can be highly risky, cumulate expenditure and reduce productivity. This concerns all major industrial applications, Oil & Gas installations and Marine applications. Working conditions are difficult and the amount of tests that can be done is strictly limited to the mandatory ones. This thesis proposes two levels of industrial controller validation which can be done in experimental test platform : an algorithm validation level called Software In the Loop (SIL) treated in the second chapter ; a physical hardware validation called Hardware In the Loop (HIL) treated in the third chapter. The SIL validates only the control algorithm, the control law and the computed references without taking into account neither the actual physical commands nor the physical input feedbacks managed by the Input/Output boards. SIL validation of the system where industrial asynchronous motor is fed and regulated by a three level Variable Speed Drive with a three level voltage source converter is treated in the second chapter with a particular modeling approach adapted to such validation. The last chapter presents the HIL validation with various hardware implementations (Field Programmable Gate Array (FPGA), processors). Such validation checks both the control algorithm and the actual physical Input/Output signals generated by the dedicated boards. Each time, the modeling approach is chosen according to the hardware implementation. Currently this work has contributed to the system validation used by General Electric - Power Conversion © (GE-PC) as part of their validation phase that is mandatory for Oil & Gas projects and Marine applications
66

Proteção digital de geradores eólicos com conversores de potência de escala completa no contexto das smart grids / Digital protection of wind generators with full- scale power converter in the smart grid context

Rodrigo Pavanello Bataglioli 02 July 2018 (has links)
Considerando condições anormais que o Sistema Elétrico de Potência (SEP) está sujeito, a proteção de seus elementos é um tópico importante. Dentre os equipamentos a serem protegidos, destacam-se os geradores devido a representarem elevado custo de investimento e estarem sujeitos a multas por paradas não programadas. Desta forma, com base em pesquisa bibliográfica, observa-se que não existem estudos abrangentes para a proteção individual de máquinas síncronas aplicadas à geração eólica. Além disso, considerando o contexto das smart grids, a presença de baterias e a possibilidade da operação ilhada podem alterar a dinâmica das situações de falta. Portanto, faz-se necessário um estudo do comportamento dos aerogeradores em situações de falha, sabendo que o esquema de proteção depende do tipo de gerador e da maneira como este está conectado ao SEP. Neste sentido, esta pesquisa propôs incluir uma bateria para operar com um gerador eólico de velocidade variável de forma complementar, suavizando a potência de saída e tornando o sistema de conversão de energia eólica forte o suficiente para operar no modo ilhado. A metodologia estabelece vários tipos de falhas para investigar o comportamento da turbina eólica em tais condições. Para realizar as simulações de falta, foi utilizado um simulador digital de tempo real (RTDS®). Com base nisso, um esquema composto por funções de proteção convencionais foi especificado e testado usando o software MATLAB®. Além disso, simulações em laço fechado foram realizadas com relés comercial e universal. Os resultados obtidos com o esquema proposto são bastante promissores. / Considering abnormal conditions to which the Electric Power System (EPS) may be subjected, the protection of its elements is an important topic. Among the equipments to be protected, the generators are highlighted, because they represent a high investment cost and are subjected to penalties for unscheduled stoppages. Hence, based on literature, it is observed that there are no comprehensive studies and standards for individual protection of Synchronous Generators (SGs) applied to Wind Energy Conversion System (WECS). Furthermore, considering the smart grids context, the presence of batteries and the possibility of island operation may change the dynamic of fault situations. Therefore, it is necessary to study and analyse the behavior of wind turbines in fault situations, knowing that the protection scheme is dependent on the generator type and the way it is connected to the EPS. In order to study these issues, this research proposed to include a battery to operate with a full-variable speed wind generator in a complementary way, smoothing the output power and making the WECS strong enough to operate in the island mode. The methodology establishes several fault types to investigate the wind turbine behavior in such conditions. In order to conduct the fault simulations, a real time digital simulator (RTDS®) was used. Based on this, a scheme composed by conventional protection functions were specified and tested using the MATLAB® software. Furthermore, hardware-in-the-loop simulations were performed with commercial and universal relays. Very good results in favor of the proposed scheme are presented.
67

Real-time Dynamic Simulation of Constrained Multibody Systems using Symbolic Computation

Uchida, Thomas Kenji January 2011 (has links)
The main objective of this research is the development of a framework for the automatic generation of systems of kinematic and dynamic equations that are suitable for real-time applications. In particular, the efficient simulation of constrained multibody systems is addressed. When modelled with ideal joints, many mechanical systems of practical interest contain closed kinematic chains, or kinematic loops, and are most conveniently modelled using a set of generalized coordinates of cardinality exceeding the degrees-of-freedom of the system. Dependent generalized coordinates add nonlinear algebraic constraint equations to the ordinary differential equations of motion, thereby producing a set of differential-algebraic equations that may be difficult to solve in an efficient yet precise manner. Several methods have been proposed for simulating such systems in real time, including index reduction, model simplification, and constraint stabilization techniques. In this work, the equations of motion are formulated symbolically using linear graph theory. The embedding technique is applied to eliminate the Lagrange multipliers from the dynamic equations and obtain one ordinary differential equation for each independent acceleration. The theory of Gröbner bases is then used to triangularize the kinematic constraint equations, thereby producing recursively solvable systems for calculating the dependent generalized coordinates given values of the independent coordinates. For systems that can be fully triangularized, the kinematic constraints are always satisfied exactly and in a fixed amount of time. Where full triangularization is not possible, a block-triangular form can be obtained that still results in more efficient simulations than existing iterative and constraint stabilization techniques. The proposed approach is applied to the kinematic and dynamic simulation of several mechanical systems, including six-bar mechanisms, parallel robots, and two vehicle suspensions: a five-link and a double-wishbone. The efficient kinematic solution generated for the latter is used in the real-time simulation of a vehicle with double-wishbone suspensions on both axles, which is implemented in a hardware- and operator-in-the-loop driving simulator. The Gröbner basis approach is particularly suitable for situations requiring very efficient simulations of multibody systems whose parameters are constant, such as the plant models in model-predictive control strategies and the vehicle models in driving simulators.
68

Real-time Dynamic Simulation of Constrained Multibody Systems using Symbolic Computation

Uchida, Thomas Kenji January 2011 (has links)
The main objective of this research is the development of a framework for the automatic generation of systems of kinematic and dynamic equations that are suitable for real-time applications. In particular, the efficient simulation of constrained multibody systems is addressed. When modelled with ideal joints, many mechanical systems of practical interest contain closed kinematic chains, or kinematic loops, and are most conveniently modelled using a set of generalized coordinates of cardinality exceeding the degrees-of-freedom of the system. Dependent generalized coordinates add nonlinear algebraic constraint equations to the ordinary differential equations of motion, thereby producing a set of differential-algebraic equations that may be difficult to solve in an efficient yet precise manner. Several methods have been proposed for simulating such systems in real time, including index reduction, model simplification, and constraint stabilization techniques. In this work, the equations of motion are formulated symbolically using linear graph theory. The embedding technique is applied to eliminate the Lagrange multipliers from the dynamic equations and obtain one ordinary differential equation for each independent acceleration. The theory of Gröbner bases is then used to triangularize the kinematic constraint equations, thereby producing recursively solvable systems for calculating the dependent generalized coordinates given values of the independent coordinates. For systems that can be fully triangularized, the kinematic constraints are always satisfied exactly and in a fixed amount of time. Where full triangularization is not possible, a block-triangular form can be obtained that still results in more efficient simulations than existing iterative and constraint stabilization techniques. The proposed approach is applied to the kinematic and dynamic simulation of several mechanical systems, including six-bar mechanisms, parallel robots, and two vehicle suspensions: a five-link and a double-wishbone. The efficient kinematic solution generated for the latter is used in the real-time simulation of a vehicle with double-wishbone suspensions on both axles, which is implemented in a hardware- and operator-in-the-loop driving simulator. The Gröbner basis approach is particularly suitable for situations requiring very efficient simulations of multibody systems whose parameters are constant, such as the plant models in model-predictive control strategies and the vehicle models in driving simulators.
69

Stratégie de protection de réseaux de transport d’électricité en courant continu multi-terminaux à l’aide de disjoncteurs mécaniques DC / Protection strategy for multi-terminal High Voltage Direct Current grids based on mechanical DC circuit breakers

Loume, Dieynaba 03 October 2017 (has links)
Les réseaux de transport d’électricité multi-terminaux à courant continu se révèlent être la solution adéquate pour une intégration massive d’énergie renouvelable dans les réseaux alternatifs existants. En effet, les réseaux en courant continu sont capables de transmettre de manière efficace des niveaux de puissance élevés sur de très longues distances par rapport aux réseaux alternatifs car, à partir d'une certaine puissance à transmettre, il existe une distance limite à partir de laquelle la transmission d’énergie en courant alternatif perd sa compétitivité face à la transmission en courant continu. L'un des principaux défis liés au développement de ces réseaux de transport d’électricité à courant continu ou Supergrid, concerne leur protection contre des défauts de type court-circuit sur des liaisons en courant continu. . Dans ce travail de thèse, un nouveau concept de stratégie de protection des réseaux en courant continu à haute tension en cas de défaut court-circuit est proposé. La stratégie repose sur une philosophie de protection ayant comme priorité la suppression du courant de défaut avant l’isolation de la liaison en défaut. Elle est basée sur l’utilisation de disjoncteurs mécaniques à courant continu sans avoir recours à des limiteurs de courant de défaut. Une séquence de protection primaire ainsi que deux séquences de sauvegarde en cas de défaillance de disjoncteurs ont été développées, testées et validées à l’aide de simulations de transitoires électromagnétiques et de simulations temps-réel. En outre, les algorithmes des relais de protection ont été implémentés avec l'aide de l’outil d’analyse fonctionnelle descendante SADT (Structured Analysis and Design System). Cette thèse a été effectuée dans le cadre du SuperGrid Institute, une plate-forme de recherche collaborative visant à développer des technologies pour les futurs réseaux de transport d'électricité et regroupant l'expertise d'industries telles que GE Grid Solutions et les laboratoires de recherche publique comme le laboratoire de génie électrique de Grenoble (G2Elab). / Multi-terminal High Voltage Direct Current (MTDC) grids,have been proven to be an adequate solution for massive integration of renewable energy power to existing High Voltage Alternating Current (HVAC) grids. Indeed, HVDC grids are capable of transmitting efficiently high level of power over very long distances compared to HVAC grids since, from a certain power to be transmitted, there is a limited distance from which the AC power transmission loses its efficiency and becomes very costly compared to DC power transmission. One of the main challenges related to the development of theses multi-terminal HVDC grids, or Supergrids, concerns their protection against DC short-circuit faults. In this thesis, a new concept of protection strategy for MTDC grids in case of permanent short-circuit fault on a DC cable has been proposed. The strategy is based on the non-selective fault clearing philosophy where the priority is given to the suppression of the fault current before isolating the faulty transmission line. The strategy is based on mechanical DC breakers and no fault current limiting devices are used. A primary protection sequence as well as two back-up sequences in case of breakers operation failure have been developed, tested and validated through Electromagnetic Transient (EMT) and Real-Time (RT) simulations. Also, algorithms to be implemented on protective relays have been designed with the help of the Structured Analysis and Design System (SADT). This PhD thesis has been performed in the frame of the SuperGrid Institute, a collaborative research platform aiming to develop technologies for the future electricity transmission network and bringing together the expertise of industries such as GE grid solutions and public research laboratories as the Grenoble Electrical Engineering Laboratory (G2Elab).
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Simulation temps-réel distribuée de modèles numériques : application au groupe motopropulseur / Distributed real-time simulation of numerical models : application to power-train

Ben Khaled-El Feki, Abir 27 May 2014 (has links)
De nos jours, la validation des unités de contrôle électronique ECU se fonde généralement sur la simulationHardware-In-the-Loop où les systèmes physiques qui manquent sont modélisés à l’aide deséquations différentielles hybrides. La complexité croissante de ce type de modèles rend le compromisentre le temps de calcul et la précision de la simulation difficile à satisfaire. Cette thèse étudie et proposedes méthodes d’analyse et d’expérimentation destinées à la co-simulation temps-réel ferme de modèlesdynamiques hybrides. Elle vise notamment à définir des solutions afin d’exploiter plus efficacement leparallélisme fourni par les architectures multi-coeurs en utilisant de nouvelles méthodes et paradigmesde l’allocation des ressources. La première phase de la thèse a étudié la possibilité d’utiliser des méthodesd’intégration numérique permettant d’adapter l’ordre comme la taille du pas de temps ainsi quede détecter les événements et ceci dans le contexte de la co-simulation modulaire avec des contraintestemps-réel faiblement dures. De plus, l’ordre d’exécution des différents modèles a été étudié afin dedémontrer l’influence du respect des dépendances de données entre les modèles couplés sur les résultatsde la simulation. Nous avons proposé pour cet objectif, une nouvelle méthode de co-simulationqui permet le parallélisme complet entre les modèles impliquant une accélération supra-linéaire sanspour autant ajouter des erreurs liées à l’ordre d’exécution. Enfin, les erreurs de retard causées par lataille de pas de communication entre les modèles ont été améliorées grâce à une nouvelle méthoded’extrapolation par contexte des signaux d’entrée. Toutes les approches proposées visent de manièreconstructive à améliorer la vitesse de simulation afin de respecter les contraintes temps-réel, tout engardant la qualité et la précision des résultats de simulation sous contrôle. Ces méthodes ont été validéespar plusieurs essais et expériences sur un modèle de moteur à combustion interne et intégrées àun prototype du logiciel xMOD. / Nowadays the validation of Electronic Control Units ECUs generally relies on Hardware-in-The-Loopsimulation where the lacking physical systems are modeled using hybrid differential equations. Theincreasing complexity of this kind of models makes the trade-off between time efficiency and the simulationaccuracy hard to satisfy. This thesis investigates and proposes some analytical and experimentalmethods towards weakly-hard real-time co-simulation of hybrid dynamical models. It seeks in particularto define solutions in order to exploit more efficiently the parallelism provided by multi-core architecturesusing new methods and paradigms of resource allocation. The first phase of the thesis studied the possibilityof using step-size and order control numerical integration methods with events detection in thecontext of real-time modular co-simulation when the time constraints are considered weakly-hard. Moreover,the execution order of the different models was studied to show the influence of keeping or not thedata dependencies between coupled models on the simulation results. We proposed for this aim a newmethod of co-simulation that allows the full parallelism between models implying supra-linear speed-upswithout adding errors related to their execution order. Finally, the delay errors due to the communicationstep-size between the models were improved thanks to a proposed context-based inputs extrapolation.All proposed approaches target constructively to enhance the simulation speed for the compliance toreal-time constraints while keeping the quality and accuracy of simulation results under control and theyare validated through several test and experiments on an internal combustion engine model and integratedto a prototype version of the xMOD software.

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