In conventional centralized power systems, power is generated mostly by large synchronous generators (SGs), where the frequency of the grid depends on the rotational frequency of the prime mover. If there are any sudden changes in the load, the rotor inertia property restrains the changes in frequency and keeps the system stable. During transient periods, rotor kinetic energy of the rotor is injected into the grid to balance power supply between generation and load. With the recent high penetration of renewable energy sources (RES), the power grid is undergoing structural changes with an increased inverter-based distributed generation. Since inverter based power sources do not have inertia as conventional synchronous machines (SM), high penetration of inverters may cause instability and sharp voltage fluctuations in the grid. If inverter based power sources could be configured as regular SM by introducing virtual inertia and damping property, many of the problems, such as frequency regulation, islanded operation, and parallel operation of inverter-based DGs will be resolved. This thesis investigates mathematical modeling and control of VSG’s to emulate the inertia and damping property of SMs. Simulation results are presented on the modeling and closed-loop performance of VSGs for an island microgrid. / Electrical and Computer Engineering

This thesis has been performed in order to earn a master's degree in electrical engineering. The task was to implement an automatic voltage regulator, AVR, to control the terminal voltage of the synchronous generator Svante at the Division of Electricity at Uppsala University. The AVR uses Bluetooth technology to transfer a control signal produced by a programmable logical controller, PLC, to phase- mounted SSRs that decides what proportion of the AC from a six-phase brushless exciter that is to be used for the magnetization of the rotor. Test runs of the AVR were preformed with a regulator optimized according to the Ziegler-Nichols method and a static exciter that uses brushes and slip rings to apply voltage to the rotor winding. The results obtained complies with the assigned requirements set for this thesis and the AVR. The primary focus of this thesis mainly lies in the construction of the control system, which include the programming of both PLC and Bluetooth communicating devices.

L’objectif de cette thèse est de développer des stratégies de commande non linéaire et robuste afin d’assurer une connexion avec succès des systèmes hydroliens dans un réseau électrique de forte puissance. Il s’agira en plus, d’étudier en simulation et en pratique le comportement dynamique de ses systèmes hydroliens commandés suite à des perturbations sévères. Dans un premier temps, nous nous sommes intéressés à la modélisation de tous les éléments de la chaine de production d’énergie hydrolienne, en partant de la marée jusqu’à la génératrice synchrone. Dans un second temps, nous avons proposé trois lois de commande non linéaire ; une pour un système hydrolien mono machine et les deux autres pour deux types de réseau électrique multi-machine. La stabilité de ces lois de commandes est prouvée en utilisant la méthode de Lyapunov et les propriétés spécifiques à la structure variable. La particularité de ces lois de commandes est qu’elles régulent simultanément la tension terminale et la fréquence en agissant uniquement sur l’excitation de la génératrice synchrone. Finalement, nous avons étudié en simulation le comportement dynamique des systèmes hydroliens commandés et les résultats obtenus sous perturbations électrique et mécanique ont montré l’efficacité de la commande proposée par rapport aux commandes CNL et AVR-PSS. Dans un souci de valider pratiquement ces résultats de simulation, la commande non linéaire proposée pour le système hydrolien mono machine est implantée sur un banc d’essai. Les résultats satisfaisants obtenus sous perturbations soutenues sont ensuite comparés à ceux obtenus pratiquement avec les commandes, CNL et AVR-PSS. / This thesis develops nonlinear and robust control strategies in order to ensure a successful connection of marine turbine systems into grid. In addition, it is a question to examine in simulation and practice the dynamic behavior of controlled marine turbine systems under severe perturbations. Firstly, we have modeled all production chain elements of marine turbine system. Secondly, we have proposed three nonlinear control strategies ; one for marine turbine system single machine connected to infinite bus and the both others for two multimachine electrical networks. The developed strategies control stability is proven mathematically by using Lyapunov method and one specific property of variable structure. These strategies control particularity is the two outputs regulation (terminal voltage and frequency) trough a single input (synchronous machine excitation). Finally, simulation results under mechanical and electrical perturbations are presented in order to highlight the robustness qualities of the proposed controllers compared to nonlinear controller CNL and classical AVR-PSS. In view of industrial applications, the proposed control for marine turbine single machine system is implemented on experimental bench. The obtained practical results under hard perturbations are very satisfactory. These results are used to realize a comparative study between the proposed control, the CNL and the AVR-PSS.

Student Number :0008015M - MSc Dissertation - School of Electrical and Information Engineering - Faculty of Engineering and the Built Environment / Shaft voltages and currents are an unavoidable characteristic of rotating machines, though they are typically a nuisance this work shows that shaft signals can be used for fault diagnosis. This work focussed on shaft voltages present on synchronous generators. Measurements on a 4-pole generator found that the angular position of the shaft could be determined from the shaft voltage. An experimental 20 kVA 2-pole synchronous generator was designed and built which resembled a full-size 600 MVA turbo-generator. The effects of a static eccentricity on the shaft voltage were successfully determined firstly through FEM simulation and then verified with physical measurements. Shaft voltages can be used to diagnose static eccentricity, future work should investigate other faults. In addition, computer simulation was found to be effective and simulation and measurements of operating machines (such as turbo-generators) should be considered.

The classical methodologies for synchronous machine modeling provide a solid estimation for synchronous machine behavior but are limited in terms of accuracy due to the assumptions made in the modeling process. The equivalent circuit model developed by the classical approach breaks down the entire machine into a singular impedance component. This allows the model to be generated more quickly but limits its accuracy. In the pursuit of developing a more realistic model, this thesis outlines the parameter measurement of a Hampden SM-100 synchronous machine. In determining the SM-100’s experimental parameters, this thesis executes and analyzes new experimental approaches to synchronous machine modeling. With the results of these approaches, a model for the Hampden SM-100 synchronous machine is developed that considers the rotor, stator, and core parameters of the synchronous machine separately.

This work deals with calculation and design of synchronous salient pole generator and then the transformation from this machine into so-called hybrid synchronous machine is described. This diploma thesis is done for company Siemens Electric Machines s.r.o. in Drásov. This company provided their design of synchronous salient pole generator. The model of this generator was created in programs RMxprt and Maxwell 2D. Suggestions and models were compared, and their calculated parameters were evaluated. The created model was upgraded to so-called hybrid synchronous generator. Permanent magnets were added in the created model and influence of these additional magnets is going to be analyzed. Tasks of the work are described in more details. in the introduction. The topic of synchronous generator and hybrid synchronous generator in general is described in the theoretical part. The next part of work deals with the design of salient pole generator. In the other part of the work calculation and design of the generator model are described in Ansys program. Furthermore there are some results from program compared with the results from company. Some model parts and other graphic outputs from Ansys program are shown. After that the creation of hybrid synchronous generator is described and created models of hybrid synchronous generators are compared and evaluated.

Within the existing available mix of numerical and analytical thermal analysis options, lumped parameter thermal modelling is selected as the operational backbone to develop an improved novel synchronous generator thermal modelling package. The objective is for the creation of a user friendly quick feedback tool, which can serve as a means to make quick machine design thermal calculations and answer customer queries quickly and reliably. Furthermore, thermally improved generator designs will allow for inevitable operational losses to be channelled away from the machine more efficiently. As a result, machine component temperatures will be reduced, allowing lower generator thermal ratings. The end result will be smaller, longer lasting, more efficient generators, with the ability to be adapted with greater ease to particular applications. With the contribution of selected numerical analysis techniques, mainly finite element analysis for the distribution of iron losses, the MySolver thermal modelling package is developed and presented in this thesis. It is this combination of numerical and analytical tools that improves synchronous generator thermal modelling accuracy, but ultimately it is the lumped parameter nature of the thermal models developed that makes MySolver succeed as a reliable quick feedback electrical machine thermal design tool, validated using experimental results for a wide range of operating conditions. The initial part of the thesis analyses the electrical machine thermal modelling techniques available today, indicating advantages and disadvantages associated with each one, and providing a rationale for the selection of lumped parameter modelling to be used by MySolver. The development of the synchronous generator lumped parameter thermal models is detailed, with examples on its construction presented. Subsequently, finite element analysis is utilised to predict the distribution of machine iron losses across the rotor and stator laminations, with the findings applied to MySolver. Furthermore, a study is performed into the lumped parameter discretisation level needed to effectively represent machine windings. MySolver is experimentally verified using experimental data from a fully instrumented synchronous generator and this data is also used to obtain further insight into the temperature distribution within the generator. In the final part results are evaluated and the use of MySolver for modelling and optimising electrical machines is discussed. Finally, appropriate conclusions on the work presented are drawn.

An average-value model of a rotating rectifier circuit in a brushless excitation system is set forth, where a detailed simulation is required to extract the essential averaged-model parameters using numerical averaging. In the proposed approach, a synchronous machine model with saturation and cross saturation and an arbitrary rotor network representation that uses a voltage-behind-reactance representation for the field winding of the main machine is proposed. This allows the field winding to be represented as branches in a circuit solver, permitting straightforward simulation with connected circuitry. Also a brushless exciter model is introduced to be compatible with the averaged-model, where the exciter armature windings are represented using a voltage-behind-reactance formulation. The resulting average-value model is verified in time domain against detailed simulation, and its validity is demonstrated in all rectifier modes of operation.

Το αντικείμενο της παρούσας διπλωματικής εργασίας είναι η κατασκευή ενός πλήρους αυτοματοποιημένου συστήματος παραγωγής και παροχής ηλεκτρικών τάσεων με τη χρήση Προγραμματιζόμενου Λογικού Ελεγκτή (PLC) και συστήματος εποπτικού ελέγχου και συλλογής πληροφοριών (SCADA). Το σύστημα βρίσκεται στο Εργαστήριο Ηλεκτρομηχανικής Μετατροπής Ενέργειας του τμήματος Ηλεκτρολόγων Μηχανικών και Τεχνολογίας Υπολογιστών. Ο αρχικός σχεδιασμός και υλοποίηση του συστήματος έγινε το 1987 από την εταιρία ΑSEA BROWN BOVERI (ABB). Με την πάροδο του χρόνου εμφανίστηκαν βασικά λειτουργικά προβλήματα τα οποία σε συνδυασμό με την ανύπαρκτη τεχνική υποστήριξη οδήγησαν στην προβληματική λειτουργία και σταδιακά στην κατάρρευση του συστήματος. Στην πορεία λειτούργησαν κάποιες παροχές (Ε1 και Ε3) μέσω κονσόλας κλασικού αυτοματισμού με μπουτόν. Έτσι, με την πρωτοβουλία του Καθηγητή Δρ. -Μηχανικού κου Αθανασίου Ν. Σαφάκα ανατέθηκαν 7 διπλωματικές εργασίες σε φοιτητές του Τμήματος Ηλεκτρολόγων Μηχανικών και Τεχνολογίας Υπολογιστών του Πανεπιστημίου Πατρών, οι οποίες είχαν ως στόχο την επαναλειτουργία του αρχικά αυτοματοποιημένου συστήματος, με χρήση Προγραμματιζόμενων Λογικών Ελεγκτών τελευταίας γενιάς. Για την πραγματοποίηση του έργου αυτού, το σύστημα μελετήθηκε εκτενώς, καταγράφηκαν όλα τα στοιχεία του και επαναλειτούργησε, σταδιακά, σε τρεις φάσεις ανάθεσης διπλωματικών εργασιών. Συγκεκριμένα πρόκειται για την παραγωγή 10 διαφορετικών τύπων τάσεων σε 12 εργαστηριακές θέσεις. Στην 3η φάση υλοποίησης και ολοκλήρωσης του έργου, όπου εντάσσεται και αυτή η διπλωματική, υλοποιήθηκαν οι εξής παροχές: • Ε6 = 0V…230V DC • Ε7 = 0V…230V DC • Ε8 = 0V…500V DC • Ε9 = 149V…450V DC • Ε10 = 150V…500V AC, 15…100Hz Πρόκειται για μεταβλητές τάσεις που παράγονται από ζεύγη ηλεκτρικών μηχανών. Οι μηχανές αυτές βρίσκονται στο υπόγειο του Εργαστηρίου Ηλεκτρομηχανικής Μετατροπής Ενέργειας και ο χειρισμός τους γίνεται από ένα φιλικό ως προς το χρήστη περιβάλλον μέσω ηλεκτρονικού υπολογιστή (σύστημα SCADA). Ο χειριστής δεν χρειάζεται να έχει ιδιαίτερες γνώσεις για να λειτουργήσει το όλο σύστημα διότι δεν έρχεται σε άμεση επαφή με τον Προγραμματιζόμενο Λογικό Ελεγκτή (PLC) , ο οποίος είναι υπεύθυνος για την σωστή λειτουργία του συστήματος. Ο χειριστής έρχεται μόνο σε επαφή με το σύστημα SCADA , το οποίο βασίζεται στο πρόγραμμα του PLC για να λειτουργήσει. Έτσι το σύστημα που υλοποιήθηκε παρέχει ασφαλιστικές δικλείδες για την αυτόματη αντιμετώπιση οποιουδήποτε είδους σφάλματος παρουσιαστεί (υλικού αλλά και χειρισμού) , προειδοποιητικά μηνύματα και καταγραφή ιστορικού βλαβών. Ουσιαστικά προλαμβάνει και αντιμετωπίζει το σφάλμα αλλά και το λάθος του χειριστή αυτόματα και ταχύτατα. Κάποια μέρη της εργασίας με ιδιαίτερο ενδιαφέρον είναι: για την διεκπεραίωση της παροχής Ε9 γίνεται παραλληλισμός σύγχρονης γεννήτριας στο δίκτυο αυτόματα μέσω του Προγραμματιζόμενου Λογικού Ελεγκτή. Επίσης δημιουργήθηκε ένας ομαλός εκκινητής (soft starter) για έλεγχο ασύγχρονης μηχανής εκμεταλλευόμενοι την παροχή Ε10. Όλες οι παροχές μπορούν να δοθούν στους εργαστηριακούς πάγκους για εκπαιδευτικούς αλλά και ερευνητικούς σκοπούς. Στην διπλωματική γίνεται εκτενή αναφορά στις παραπάνω παροχές ,στις συνδεσμολογίες που κάναμε ,στον προγραμματισμό του PLC καθώς και στο σύστημα SCADA που έρχεται σε επαφή ο χειριστής. / This diploma thesis’ objective was to create a fully automated electrical voltage production and supply system using Programmable Logical Controller (PLC) and Supervisory Control and Data Acquisition (SCADA). This system is located in the Electromechanical Energy Conversion Laboratory of Electrical and Computer Engineering Department. The initial design and implementation of the system was in 1987 by ΑSEA BROWN BOVERI (ABB). The basic operational problems combined with little technical support led to the insufficient operation and gradually to the collapse of the system. Some supplies (E1 and E3) operated later on, using typical automation control with button console. So, Professor Dr.-Ing. Athanasios N. Safacas initiated the reoperation of the automated system with the use of new PLCs. For this purpose he assigned seven diploma thesis to the students of Electrical and Computer Engineering Department. To complete the project, the system had to be fully analyzed and its components fully registered. The project was finalized after three phases. The system includes 10 different types of electrical voltage in 12 different laboratory locations. During the third phase, that this diploma thesis is part of, the following supplies needed to be implemented : • Ε6 = 0V…230V DC • Ε7 = 0V…230V DC • Ε8 = 0V…500V DC • Ε9 = 149V…450V DC • Ε10 = 150V…500V AC, 15…100Hz These are variable voltage that are produced by electrical machine pairs. The machine are located at the basement of Electromechanical Energy Conversion Laboratory and they are operated by SCADA. The system is operated exclusively by SCADA ,so the operator doesn’t need to have special knowledge of the whole system. The system is secured against any error (hardware or operation) and offers warning messaging and saves error history. Some sections of great interest are: • The E9 supply operates through parallelism of synchronous generator with the energy network. This is achieved auto by the Programmable Logical Controller. • The E10 supply was used to provide a soft starter simulation in order to control the speed of asynchronous machine. In the diploma thesis includes all the information about the power supplies, the connections that were made, the PLC programming and the making of the SCADA system.

Orientador: Walmir de Freitas Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-13T11:32:14Z (GMT). No. of bitstreams: 1 Trindade_FernandaCasenoLima_M.pdf: 1160331 bytes, checksum: 8645597088992da29acb335423c8dbc4 (MD5) Previous issue date: 2009 / Resumo: Sistemas industriais modernos são instalações bastante complexas com elevado grau de automatização e com capacidade de operar de forma isolada (ilhada) da rede elétrica após a ocorrência de contingências devido à utilização de geradores próprios compostos principalmente por máquinas síncronas e turbinas térmicas. Tais instalações, na presença de geradores, são denominadas genericamente como consumidores autoprodutores. Como muitos desses autoprodutores são conectados em redes de distribuição e subtransmissão de energia elétrica, tais consumidores estão sujeitos às normas técnicas requeridas por essas concessionárias. Assim, a desconexão da instalação industrial logo após a ocorrência de um ilhamento na rede de distribuição é um procedimento obrigatório. Imediatamente após a detecção do ilhamento pelo sistema de proteção da instalação industrial, a rede de distribuição e o sistema industrial são separados (isolados). Esta separação é realizada através da abertura do disjuntor instalado no lado de baixa tensão do transformador (lado do consumidor) que faz a conexão entre os dois sistemas. Então, a concessionária pode realizar os procedimentos necessários para reenergização da rede. Logo após a realização da separação dos sistemas, é necessário adotar uma série de medidas que garanta que o sistema industrial possa continuar operando isoladamente de forma adequada. Basicamente, três ações devem ser tomadas: (a) mudança do modo de operação do regulador de velocidade e do sistema de excitação dos geradores síncronos; (b) implementação do sistema de rejeição de carga e (c) alteração dos ajustes dos relés de sobrecorrente do sistema de proteção da rede industrial. Nesse contexto, o objetivo desta dissertação de mestrado é investigar tais procedimentos e propor metodologias de análise dessas questões previamente mencionadas de forma a obter um melhor entendimento do problema. Com o desenvolvimento dessas metodologias, objetiva-se que os estudos desses procedimentos automáticos possam ser realizados de forma mais eficiente e sistemática. / Abstract: Modern industrial systems are very sophisticated installations with a high number of automatic processes and capability of isolated (islanded) operation after contingences by using onsite generators composed mainly by synchronous machines and steam turbines. Such installations, in the presence of generators, are generically called autoproducers. Since many of these autoproducers are connected to electrical power distribution and subtransmission grids, they must respect the technical recommendations imposed by these utilities. As a consequence, the disconnection of these systems from the grid after islanding occurrence is a mandatory procedure. Soon after the islanding detection by the industrial protection system, the industry and the grid must be electrically separated (isolated) by opening the circuit breaker installed at the low voltage side of the interconnection transformer. Thus, after the separation, the utility can carry out the necessary technical procedures to restore the network. From the industrial system perspective, after the separation, it is necessary to take control actions to guarantee that the industrial system continues operating with quality and reliability. Basically, three actions must be taken: (a) change the operation mode of the speed governor and excitation system of the generators; (b) implement the load shedding system and (c) change the settings of the protection system overcurrent relays. In this context, the objective of this master thesis is to investigate these procedures and propose methods for analysis in order to obtain a better understanding of these issues. With this methodologies development, it is expected that new automatic proceedings can be achieved in a more efficient and systematic way. / Mestrado / Energia Eletrica / Mestre em Engenharia Elétrica