“High voltage direct current” (HVDC) teknologi har blivit allt viktigare teknik för att integrera förnybara energikällor i elnätet. För att styra ett sådant elsystem på bästa möjliga sätt krävs optimala kontrollstatergier både för omvandlarna och nätet. Så syftet med detta projekt är att undersöka hur olika regleringsmetoder, såsom centraliseradoch distribuerad spänningskontroll, kan påverka driften i ett 4-terminal HVDC-system. Ett optimalt effektflöde uppstår i systemet endast när likspänningen inte avviker från sitt börvärde och det uppnås genom att ha aktiv effekt regulator i varje nod i nätet. Olika scenarier som ändring av effektens börvärde och omvandlaravbrott har simulerats med hjälp av HIL-processen i realtid. Simuleringarna hjälper till att analysera hur väl dem implementerade regleringsmetoder i nodernas regulatorer hantera dessa förändringar. Resultatet ger bevis på att både centraliseradoch distruebued metoden har positiva och negativa aspekter. Fördelen med centraliserade metoden är att den ger en väldefinierad operationspunkt men den hanterar den inte svåra transienter (tex. avbrott) vilket distribuerade metoden gör.

Information and communication technologies are being implemented more than ever in the power industry in order to make smarter power grids, termed as cyber-physical power systems (CPPSs). Along with the privileges of such modern power networks like reducing the total operation cost for end-use customers, they may be negatively affected by cyberattacks, above all false data injection (FDI) attacks as they are easier to be performed. As a case in point, an adversary can detour security systems, penetrate into the cyber layer of a typical CPPS, and manipulate the information, finally leading to security threats. Although prevention and detection mechanisms are significant tools to be utilized by power system operators to improve the reliability of such systems against cyberattacks, they cannot ensure the security of power grids since some FDI attacks might be designed to bypass the detection stage. Hence, a more powerful tool will be required, which is called remedial action scheme (RAS), to be implemented by power system operators to recover the targeted power grid in a timely manner. Toward this end, different RAS frameworks are presented in this dissertation in transmission, distribution, and microgrid levels to highlight the effectiveness of such reaction mechanisms in case of cyber threats targeting modern power systems. In the transmission level, optimal power flow (OPF) integrated with thyristor controlled series capacitor (TCSC) have been utilized to design a RAS to mitigate the negative impacts of FDI attacks, resulting in system congestion or power outages. In the distribution level, system operators take advantage of static VAR compensator (SVC) through solving a customized version of distribution feeder reconfiguration (DFR) problem to mitigate voltage violations in the form of overvoltages and undervolatges, caused by FDI cyberattacks. In light of the fact that some FDI attacks bypass the employed detection methods, it is crucial to prepare in advance for such scenarios. Hence, in this dissertation, a real-world framework is also proposed for mitigating false data injection (FDI) attacks targeting a lab-scale wind/PV microgrid and resulting in power shortage. The proposed RAS is developed as a hardware-in-the-loop (HIL) testbed within the cyber-physical structure of the smart microgrid. Finally, as a prerequisite of the proposed intelligent RAS, which is able to be used on different levels of a CPPS, power system operator is being in attacker’s shoe to scrutinize different scenarios of cyberattacks to make an initial archive set. The design of such mechanisms incorporates long-short-term memory (LSTM) cells into a deep recurrent neural network (DRNN) for the processing of archived data, termed intelligent archive framework (IAF), identifying the proper reaction mechanisms for different FDI cyberattacks. To react to cyberattacks for which similar pre-investigated remedial measures were not saved in the IAF, a power flow analysis is considered to a) examine the interdependency between transmission and distribution sectors and b) generate appropriate RASs in real time.

No description available.

No description available.

An accurate estimation of the charging time of an automotive traction battery is possible only with the knowledge of different parameters of the battery and the vehicle. If this information is not available to the driver, the full time needed for charging of the battery may have to be assessed only from experience. A long route planning and estimation of required service life of the vehicle are therefore only roughly possible. Furthermore, with a better knowledge of estimated charging time, better management of public charging stations and better utilization of charging equipment can be achieved. An algorithm based on Matlab/Simulink model is made in the present thesis to estimate the charging time of a Li-ion battery pack which consists of 32 cells with 40 Ah each, as well as to investigate the impact of different cell balancing methods and different charging strategies on charging process. The theoretical background of the battery and charging modelling is investigated and different battery models are compared to get the best trade-off between the model accuracy and computation complexity. In the end, an electrical equivalent circuit model from reference [1], consists of a series resistor and two ZARC elements, is chosen to represent the battery cell. The parameters of the equivalent circuit are updated according to the SOC, current and temperature changes during the charging process. The whole simulation model of the algorithm consists of a charging controller (implementing the charging strategy), cell balancing logic controller, and cell balancing hardware simulation circuit and battery cell models. Different balancing criteria: based on SOC (with PWM drive) and based on terminal voltage (with/without advance) are implemented in the cell balancing logic controller, as well as different balancing windows, to investigate their impact on charging time. As for charging strategy, traditional CCCV is investigated, further investigation is conducted into improved CCCV method. The impact of initial SOC, charging rate and aging factor on charging behavior are investigated as well. Experiment results are validated by the comparison of the results with the ones got from a Hardware-in-the-loop simulation system. / En noggrann estimering av laddtiden hos batterier avsedda för traktionsapplikationer kräver kunskap kring batteriets och dess tillhörande laddsystems parametervärden. Utan tillgång till denna information kan laddtiden endast uppskattas från fordonsägarens tidigare erfarenheter vilket försvårar t.ex. ruttplanering. En estimering av laddtiden med tillräcklig noggrannhet kan även möjliggöra bättre utnyttjade av laddutrusting inklusive nyttjandet av publika laddstationer. I detta examensarbete har en algoritm, implementerad i Matlab/Simulink, för att estimera laddtiden hos ett litiumjonbatteripack bestående av 32 celler på vardera 40 Ah tagits fram. Med hjälp av modellen har olika laddstrategier och metoder för att balansera cellerna studerats. Ett antal olika batterimodeller har jämförts i termer av noggrannhet och krav på beräkningsprestanda. En elektriskt ekvivalent krets från referens [1], bestående av en serieresistans samt två ZARC-element, valdes slutligen för att representera battericellen. Den ekvivalenta kretsens parametrar uppdateras vid förändringar i SOC, ström och temperatur. Hela simuleringsmodellen består av en laddregulator (i vilken laddstrategin är implementerad), cellbalanseringregulator och modeller för cell och cellbalanseringens hårdvara. Ett antal metoder för att balanser cellerna har jämförts med hänsyn till påverkan på den resulterande laddtiden. En traditionell samt modifierad CCCV laddstrategi har implementerats och jämförts med avseende på variationer i inledande SOC, total laddtid samt åldring. Experimentella resultat från en hardware-in-the-loop simulering har använts för att delvis kunna verifiera de framtagna resultaten.

In order to meet the increasing demand ofenergy in today’s society while at the same time minimizing theenvironmental impact, renewable energy sources will be requiredto be integrated into the existing energy mix. Technologicaladvances in high voltage direct current (HVDC) grids playa crucial role in making this possible. Therefore the purposeof this project has been to validate the properties of basiccontrol strategies in terms of how they respond to four differentsimulation cases. All simulations have been conducted on asimplified version of the CIGR ́E B4 test grid, consisting offour monopolar HVDC converters. After analyzing the resultsobtained from each control strategy it became evident thatprovided if the benefits of the redundancy introduced by amulti-terminal grid are to be fully utilized, a distributed voltagecontrol should be used. Moreover, after substituting one ofthe four internal controllers with an external one, it becameclear that simply deciding the droop constants based on resultsfrom the simulation model wouldn’t be sufficient for real worldapplications. / För att möta det ökande energibehovet i dagens samhälle, samtidigt som energiproduktionens miljöpåverkan ska minimeras, krävs det att förnyelsebara energikällor integreras i den existerande energimixen. Tekniska framsteg inom högspända likströmsnät (HVDC) spelar en avgörande roll i att göra detta möjligt. Därför har syftet med detta projekt varit att validera egenskaperna hos grundläggande kontrollstrategier efter hur dem reagerar på fyra olika simuleringsfall. Alla simuleringar har genomförts på en förenklad version av CIGRE´ B4 testsystem, bestående av fyra monopolära HVDC omriktare. Efter att analyserat de erhållna resultaten från varje kontrollstrategi blev det uppenbart att om fördelarna med multiterminala elnät skulle uppnås, bör en distribuerad spänningskontroll användas. Dessutom, efter att ha bytt ut en av dem fyra interna kontrollerna med en extern, visade det sig att endast bestämma droppkonstanterna baserat på resultat från simuleringsmodellen inte är tillräckligt för verkliga applikationer. / Kandidatexjobb i elektroteknik 2020, KTH, Stockholm

Stability and sustainability of operation of interconnected power converter systems has been an important focus of study in the field of power electronics and power systems. With ever-increasing application of electrical machines by means of electrification of vehicles, airplanes and shipboards, detailed study of the relating dynamics is very important to ensure the proper implementation and stable behavior of the overall system. In this work, the application of the black box approach study of the power converters has been expanded to the electrical machines. Using this modeling method, it is possible of have accurate behavior of electrical and mechanical terminals of the machine without the detailed information about the internal structure of the machine, material characteristics or topology of the machine. Instead, accurate model of electrical and mechanical terminals of the machine are achieved by measuring specific frequency responses of the machine to distinguish dynamic relation of the various electrical and mechanical quantities of the machine. The directly measured frequency responses, are coupled with the dynamics of the source and load in the electrical and mechanical terminals of the machine thus in order to decoupled the described couplings a mathematical process is used that results in decoupling of the controller and drive on the electrical side and the dynamics of the mechanical load and mechanical shaft at the mechanical terminal of the machine. Resulting model is the linear time invariant representation of the electrical machine at a specific operating point. Additionally, this work represents the application of this modeling method for accurate measurement of internal parameters of the machine such as inductances and mechanical inertia and characterization of the mechanical shaft coupler. Resulting unterminated model of the machine is a very important matter of information for system integrators and electrical and mechanical designs related to the application of the machine, to ensure the stable and sustainable operation of the machine. This work for the first time, represents the experimental implementation of this terminal behavioral modeling method for studying electrical machines as well as describes some of the practical limitations of this methodology. By incorporating and integrating a combination of commercially available devices such as frequency response analyzer, Hardware-In-The-Loop (HIL), Power-Hardware-In-The-Loop (PHIL), a test setup has been developed that is capable of control, operate and study arbitrary frame small-signal related measurements required for terminal behavioral study of the electrical machines. Resulting model of the machine that has been extracted from this modeling method is then used to compare in time domain with the real machine in the case of transient change in the mechanical load on the shaft to discover the validity of this modeling procedure. / Master of Science / According to the data from the International Energy Agency, around half of the electricity used globally is consumed by electric motors. Moreover, the growth in the electrical vehicle industry will increase their application even further, hence the development of high-fidelity models of electric machines for real-time emulation, system-level analyses, and stability studies still stands out as an important and needed research focus. New modeling concepts that go beyond the standard industry practice can be used at the design and integration stage to ensure the stable behavior of the overall system. Furthermore, convenient testing and identification pressures can help ensure the long-term operation of the system. Aligned with this trend, this thesis is studying permanent magnet synchronous machines (PMSM) using small-signal terminal-behavioral three-port networks. Having such a behavioral model of the machine available provides many opportunities for system integrators, and even enables an in-situ system observation and stability assessment at both the machine's electrical and mechanical interfaces. This capability can undoubtedly be of high importance in practice, as it is offering new insights into dynamic interactions of the electro-mechanical systems, the governor or turbine control design in ships, aircrafts, electrical vehicles, and even large synchronous machines in power plants. A so-called characterization testbed has been built that combines Hardware-In-The-Loop (HIL) and Power-Hardware-In-The-Loop (PHIL) environments, with sensor-interface boards that are used to properly scale measured signals for machine control. The Frequency-Response-Analyzer is used to sweep the proper electrical or mechanical terminal of the machine by perturbing the proper control signal within the machine controller running in PHIL and reading d-q currents, voltages, torque, and speed variables whose dynamic ratios are then obtained without the need for interrupting the normal operation of the electrical machine. The capability of acquiring such a detailed model of the machine while the machine is in operation is an important benefit of this modeling method, in comparison to the conventional identification methods widely applied in the industry. The resulting model is a linearized time invariant representation of the electrical machine at a specific operating point of interest, and can be used by system integrators to ensure the stability of the system using well known stability assessment methodologies. Furthermore, this modeling strategy has been experimentally verified for the first time on electrical machines, and the resulting model has been compared with the transient behavior of the machine in the presence of a step change in the mechanical load of the machine.

Les travaux de cette thèse s’inscrivent dans le cadre de la mise en place d’une méthodologie innovante de gestion thermique globale des véhicules automobiles. Ils portent plus particulièrement sur l’analyse de la réduction des émissions de polluants et l’amélioration des performances énergétiques d’un moteur à combustion, notamment dans les charges partielles ou en régime transitoire. Le premier objectif vise la mise en évidence de l’effet de la température d’admission sur le fonctionnement du moteur. Le deuxième objectif est relatif à la prédiction de l’apparition des phénomènes de condensation inhérents aux procédés de recirculation des gaz d’échappement à l’admission moteur. Enfin le troisième objectif est la modélisation et la mise en œuvre d’un circuit d’eau refroidit par la boucle de climatisation dont la fonction est de sous refroidir les gaz d’admission du moteur. Le premier chapitre est consacré à la présentation du système thermique véhicule et de la démarche de conception en V adoptée dans ce travail. Dans le second chapitre, et après avoir mis en évidence les effets d’un sous refroidissement des gaz admission sur le rendement thermodynamique du moteur, on montre à l’aide d’une étude technologique et numérique de la boucle de climatisation qu’il est possible d’opérer ce refroidissement par un système embarqué capable de se régénérer thermiquement lors d’un freinage. Le troisième chapitre est dédié à la modélisation du système à l’aide d’une modélisation énergétique centrée sur l’utilisation du langage bond graph. Le dernier chapitre est dédié au volet expérimental afin de valider d’une part le modèle de condensation et d’autres part un démonstrateur d’hybridation thermique et ses stratégies de pilotage / The work of this thesis is part of the development of an innovative methodology in the field of global thermal management for motor vehicles. It focuses specifically on the analysis of the reduction of pollutant emissions and improving energy efficiency of a combustion engine, especially in partial load or transient operation. The first objective is to analyze the effect of inlet temperature on the engine performance. The second objective relates to the prediction of the condensation processes inherent to exhaust gas recirculation into the engine intake. Finally, the third objective is the modeling and implementation of a water circuit cooled by the air conditioning loop and whose function is to cool the gases in at the engine intake.The first chapter is devoted to the presentation of the vehicle thermal management system and the design process adopted in this work. In the second chapter, after having shown the effects of intake gas cooling on the thermodynamic efficiency of the engine, it is shown with a numerical and technological study of the air conditioning loop that is possible to operate an onboard cooling system that is capable of regenerating heat when braking. The third chapter focuses on system modeling using an energy modeling focuses on the use of bond graph language. The final chapter is dedicated to the experimental part with the objective of validating the model of gas condensation and a demonstrator of thermal hybridation and its control strategies

Vehicle Dynamics Control (VDC) systems (also known as Active Chassis systems) are mechatronic systems developed for improving vehicle comfort, handling and/or stability. Traditionally, most of these systems have been individually developed and manufactured by various suppliers and utilised by automotive manufacturers. These decentralised control systems usually improve one aspect of vehicle performance and in some cases even worsen some other features of the vehicle. Although the benefit of the stand-alone VDC systems has been proven, however, by increasing the number of the active systems in vehicles, the importance of controlling them in a coordinated and integrated manner to reduce the system complexity, eliminate the possible conflicts as well as expand the system operational envelope, has become predominant. The subject of Integrated Vehicle Dynamics Control (IVDC) for improving the overall vehicle performance in the existence of several VDC active systems has recently become the topic of many research and development activities in both academia and industries Several approaches have been proposed for integration of vehicle control systems, which range from the simple and obvious solution of networking the sensors, actuators and processors signals through different protocols like CAN or FlexRay, to some sort of complicated multi-layered, multi-variable control architectures. In fact, development of an integrated control system is a challenging multidisciplinary task and should be able to reduce the complexity, increase the flexibility and improve the overall performance of the vehicle. The aim of this thesis is to develop a low-cost control scheme for integration of Electric Power-Assisted Steering (EPAS) system with Enhanced Stability Program (ESP) system to improve driver comfort as well as vehicle safety. In this dissertation, a systematic approach toward a modular, flexible and reconfigurable control architecture for integrated vehicle dynamics control systems is proposed which can be implemented in real time environment with low computational cost. The proposed control architecture, so named “Integrated Vehicle Control System (IVCS)”, is customised for integration of EPAS and ESP control systems. IVCS architecture consists of three cascade control loops, including high-level vehicle control, low-level (steering torque and brake slip) control and smart actuator (EPAS and EHB) control systems. The controllers are designed based on Youla parameterisation (closed-loop shaping) method. A fast, adaptive and reconfigurable control allocation scheme is proposed to coordinate the control of EPAS and ESP systems. An integrated ESP & ESP HiL/RCP system including the real EPAS and Electro Hydraulic Brake (EHB) smart actuators integrated with a virtual vehicle model (using CarMaker/HiL®) with driver in the loop capability is designed and utilised as a rapid control development platform to verify and validate the developed control systems in real time environment. Integrated Vehicle Dynamic Control is one of the most promising and challenging research and development topics. A general architecture and control logic of the IVDC system based on a modular and reconfigurable control allocation scheme for redundant systems is presented in this research. The proposed fault tolerant configuration is applicable for not only integrated control of EPAS and ESP system but also for integration of other types of the vehicle active systems which could be the subject of future works.

Lors de l’installation d’une pompe à chaleur (PAC) double service (chauffage et eau chaude sanitaire (ECS)) dans le secteur résidentiel, la phase de mise en service est délicate : les paramètres à renseigner sont nombreux et non triviaux. Or, le bon fonctionnement de la PAC est très sensible à la qualité de cette étape. Quelques mauvais réglages peuvent entraîner un fonctionnement non optimal, voire un dysfonctionnement important (confort mal assuré). L’objectif de la thèse est de mettre au point une méthode de paramétrage auto-adaptatif modifiant les valeurs de « sortie d’usine » des paramètres pour les adapter au réseau d'émetteurs, à la réponse thermique du bâtiment et aux habitudes chauffage et de consommation d'ECS des occupants. Les paramètres doivent être adaptés à partir des capteurs déjà en place sur la PAC.Le travail de thèse porte d'abord sur l’identification des paramètres clés de la PAC, ceux qui influencent le plus la consommation. On en déduit quelques fonctions à optimiser : ajustement de la loi d'eau, méthode de choix des meilleures séquences de production d'ECS, anticipation de la relance du chauffage. L'objectif est de maximiser le coefficient de performance et de minimiser le recours aux appoints électriques tout en garantissant le confort. Ces objectifs sont atteints en développant des algorithmes de contrôle optimisé. Des modèles neuronaux de prévision de la réponse thermique du bâtiment, du stock d’ECS et des performances de la PAC ont été développés pour ce contrôle optimisé. Les modèles et algorithmes développés ont été validés numériquement et les performances de la PAC comparées à celles avec contrôle classique sans auto-paramétrage. Les solutions proposées ont été appliquées et testées durant une saison sur une PAC réelle sur un banc d'essai semi-virtuel (climat réel et bâtiment virtuel). / Setting control parameters of residential double service heat pumps at the time of installation and commissioning is a delicate matter. Indeed, some parameters are not trivial, there are many to be adjusted and the heat pump operations are quite sensitive to the parameters' values. Poor parameterization can lead to suboptimal heat pump operation or even to important dysfunction (harming thermal comfort).Hence, this thesis aims to develop a method for the heat pump to self-adapt the value of its control parameters. The heat pump should modify if required the "default" settings in order to adapt them to the heat emitters, to the building thermal response and to the occupancy (in terms of thermal comfort and DHW needs). For industrial reasons, this method should use on-board sensors.First, the thesis focuses on identifying the key parameters of the heat pump control, i.e. those with greatest influence on the consumption. This leads to the functions which have to be optimized: heating curve adjustment, time of DHW generation, heating setback anticipation. The objective is to maximize the coefficient of performance and minimize the use of electrical back-ups while ensuring comfort. This is achieved by developing optimized control algorithms. Thanks to forecasts models, based on neural networks, we are able to predict on a short term horizon the building thermal response, the DHW availability and the heat pump performances. The developed models and algorithms have been validated through numerical simulations, and we have evaluated the heat pump performances in comparison to a classic control. The proposed solutions were applied and tested during a heating season on a real heat pump installed in a semi-virtual test bench (real weather and virtual building).