Hydropower is a flexible energy source that is essential for balancing the electrical power system on all timescales, from seconds to years. In addition to intra-hour regulation, it provides frequency containment reserves (FCR-N,FCR-D) and frequency restoration reserves (mFRR, aFRR) to the grid. The turbine governor is a device responsible for controlling the power output and delivering frequency control to the system. The aim of this Master’s Thesis project is to develop a new hydropower turbine governor in MATLAB/Simulink, which contains all critical functionality from the existing governor and with the same performance. The new governor should as far as possible comply to the well-established communication standard IEC 61850. A working model of the turbine governor has been built in Simulink that supports normal operation with frequency control, start and stop, load rejection, operation mode as synchronous condenser and more. Validations of the model against data from Akkats powerplant shows that the model behaves as a real governor during normal operation. Validations of the start sequence showed deviations during sequence 3 and 4 which can be explained by usage of different PID parameters. Using IEC 61850 as a nomenclature and as a way of structuring functions in the governor has also been possible. Implementing the whole standard for communication, requires that the control system also is renewed according to IEC 61850. Certain functions, as sequencing has thus not been done according to the standard. MATLAB and Simulink provide tools for building, simulating and testing implementations of the turbine governor. The contributions this platform can provide are; ease of implementation, optimization and testing of control strategies. Simulink also provides a graphical interface, which reduce system complexity. An optimal implementation requires a hardware with support for Simulink to get a transparent platform. Ultimately, these benefits could result in better frequency quality at a lower cost, which is essential for successful and cost-effective integration of other renewable energy sources such as wind- and solar power.

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本論文是在日本帝國經濟構造的脈絡之下，來檢討日本政府跟臺灣總督府在糧食政策制定過程的互動關係，以及臺灣總督府對臺灣米穀政策之調整。本論文以此問題意識出發，有幾點問題的釐清與發現，以下分別敘述之。 　　日本帝國在明治維新之後邁進產業革命化，在此之後日本帝國漸漸從農業國家變成工業國家，這導致勞動者與技術者流入都市，使都市人口增加率自1890年開始慢慢增加。這些大量流入都市的人口，導致日本帝國出現米穀不足的現象。為了解決國內米穀不足的問題，日本政府開始大量進口外國米，在日俄戰爭前後每年所需的外國米就有200到500萬石。 日本帝國糧食不足的問題也使日本在1900年之後從糧食出口國變成糧食進口國。 　　日本政府在面對糧食不足的問題時，主要是仰賴進口外國米來解決，殖民地米的進口則是處於輔助地位。此時，臺灣總督府為因應日本帝國糧食不足的問題，從1903年開始增加臺灣米移入到日本的數量。但是，這仍無法解決日本糧食不足的問題，因為臺灣米與日本米的口感不相同，所以輸出量無法提升。為此，臺灣總督府開始進行米穀的品種改良政策。 　　1918年受到米騷動的影響，日本政府開始構想包含日本米與殖民地米的糧食自給政策，並於1920年正式提出以日本國內的開墾事業及朝鮮米的增殖計劃為核心的方案。但是，糧食自給政策的施行並不順利，1924到1925年間的日本還面臨外匯嚴重不足的問題，日本政府便轉為注重殖民地米的輸入。此時，臺灣開發出蓬萊米、宣告米穀品種改良的成功，在此狀況下蓬萊米輸往日本的數量亦逐年提升。因為輸出量的提升，臺灣總督府在日本政府的要求之下，從1920年後半開始擬定蓬萊米增產計劃，並在1930年的「臨時產業調查會」被提出討論。由此可知，臺灣蓬萊米在此時對於日本的糧食政策之影響力，乃隨著輸出量提升而逐漸變大。 　　日本帝國在經歷世界大恐慌之後，因為日本國內米穀的大豐收，導致米穀過剩的狀況出現。為此，日本政府開始管制殖民地米輸往日本的數量，並在1933年提出了「米穀統制法」，以管制日本國內的米穀供需量。但是，因為「米穀統制法」而產生的高米價不僅沒有解決日本米大豐收的問題，反而使殖民地米輸往日本的數量不斷提升，尤其是指相對低價格的蓬萊米。為了解決這個問題，日本政府於1936年實施「米穀自治管理法」，加強對於殖民地米輸往日本移出量的控管。 　　在臺灣方面，日本政府為了控管蓬萊米的移出，要求臺灣總督府施行「臺灣米穀移出管理令」。雖然臺灣總督府在中日戰爭爆發後，被日本政府要求必須抑制米穀耕作面積的擴大，但臺灣總督府在聽命於日本政府的同時，也隨即提出了一漸進式的米穀增產計畫。這是因為自1920年代以來，蓬萊米輸往日本的數量擴大，並在日本糧食自給政策之中扮演重要角色，從而無形中提升臺灣在日本帝國的地位。但是，當蓬萊米輸日被限制後，就意味著此一重要性的喪失，這是臺灣總督府所不願意見到，這也是為何臺灣總督府從一開始就不願意放棄蓬萊米增產計畫的原因。 　　在1930年代日本政府為了解決日本米大豐收的問題而開始控管殖民地米之際，雖然有法規的限制，但蓬萊米輸往日本的數量並沒有減少。此外，當日本於1936年加強對殖民地米的管制，並進一步要求臺灣總督府必須施行米穀移出管理令時，臺灣總督府在不得不聽日本政府命令的同時，卻仍提出蓬萊米增殖計劃。 　　透過以上問題的處理，可以看出一開始臺灣總督府在面對日本政府的糧食政策時，主要是為了配合日本人的要求及提高對日本的移出量，並因此展開米穀改良政策。從這時候看來，臺灣總督府在米穀政策的擬定上，對日本政府是處在從屬位置，這樣的情況在1922年蓬萊米開發成功之後，慢慢改變。隨著蓬萊米的開發成功，臺灣米對日本的移出量漸漸上升，又因為日本政府外匯的缺乏與糧食自給政策施展不順利，蓬萊米對日本糧食自給政策的影響力逐漸提高，這也使得臺灣總督府的立場逐漸顯現。再加上，從日本政府蓬萊米增殖計劃的提出看來，臺灣總督府表面上是聽從了日本政府的命令，但實際仍是想要進行蓬萊米的增產。而且，臺灣總督府已經從最初從屬於日本政府，轉而漸漸有自己立場出現。為了保有臺灣在日本帝國的地位，臺灣總督府甚至在日本政府的限制下，仍是持續發展蓬萊米的增產計劃。 　　總的來說，透過1900年到1942年臺灣總督府與日本政府在糧食政策上面的互動，可以看出日本政府在施行糧食政策的時候，乃會因著國內的糧食狀況而隨時進行調整，臺灣總督府在這個過程中所展現出來的態度，也就不是一成不變。

本文試圖釐清總督府圖書館建立之歷史脈絡，同時以「閱覽者」為問題中心而出發，透過統計與史料呈現，試圖勾陳出閱覽者的身分，以及閱覽者如何與為何使用圖書館，進一步讓該館閱覽者使用圖書館的歷史，得以呈現。 　　經由本文，發現下列五點，茲陳列如下。首先，該館藏書與閱覽者使用藏書方向，出現些微差異。該館藏書以和漢書為主。觀察和漢書的歷年度藏書部分，主要以「總類」、「文學、語學」等類為主；然而，依照歷年閱覽借閱累計總量排序，最受館內成人閱覽者愛好之分類，依次為「文學、語學」、「總類」等類。可發現，藏書方向與閱覽者使用方向，呈現不一致的結果。 其次，館內閱覽者以內地男性學生為大宗，館外閱覽者則量上最高者為本島男性。閱覽者職業表現方面，館內閱覽者中，以學生占絕對多數，館外閱覽者則未見資料。 　　再者，閱覽者實際使用表現中，「準備考試」是館內閱覽者使用該館的主要行為，可以看到許多內地男學生以預備考試為目的，來使用圖書館硬體和館藏中的參考書籍。館外閱覽者則暫時未得見普遍動機。 　　還有，在硬體部分，在圖書館初期，閱覽者使用圖書館時，常得面臨到座位不足的問題。同時，在圖書館營運後期逐漸嚴重的藏書區不足之問題，乃至該館缺乏餐廳和休息室，加上採光和通風不良，及缺乏防火設備等，都是閱覽者使用時所面臨到的困難。特別是營運後期進館人次屢創高峰，當閱覽者湧入時，人聲、木屐、鞋子所造成的聲響，產生整體圖書館整體閱讀環境水準不良的情況。 　　最後，自本文研究中，總督府圖書館閱覽者在該館營運期間，由於「閱讀」的行為，因而與圖書館產生了相應的互動結果。對大部分的圖書館閱覽者而言，欲使用的只是圖書館的設備，以幫助自己通過考試，而圖書館館藏或者活動，是其自身動機獲得滿足後，空閒時才考慮是否使用。也就是說，閱覽者在其總督府圖書館的使用歷程中，擁有一定的主動空間，可以選擇使用該館的方式，而非服膺圖書館自社會教育出發，必然存在教化功能的命題，或純然而無條件接受社會教育之教化。在此，歷史行動者的主體性似乎隱約得見。 / This study aims to uncover the history of the readers in the library of Office of the Taiwan Governor-General during Japanese colonial period. We want to investigate the readers in this library would be consisted of whom and what reason. By analyzing the tones of statistics data and historical material from the library, we find out the readers’ occupations and motivations eventually. With this reach, there are five points need to be mentioned. First, collection of books which stored by the library are indirect to readers’ favorite categories. Observing the data, we exposed the library had collected the category “General” most, and then is “literature and language”. In contrast, the most favorite books in this library are “literature and language”. It would be known that there is different between collection in library and readers’ favorite books. Second, in this library, most readers are Japanese male students. Comparing to this, most outside readers who use the circle service（巡迴書庫） were Taiwanese male, and it is pity that we don’t know the exactly occupation of these outside reader because of data locking. Furthermore, what were the real activities when readers were in the library？It is very interesting that preparing examinations were the main behavior. Most of Japanese male students used the equipment and the books to prepare the subjects for examinations. Unfortunately, the circle service readers’ purpose had not been discovered yet. Fourth, this building of library did not build as a library’ standard in the beginning. Therefore, readers faced the problem that they would not find enough seats inner the library. As time pass by, problem got worse. The library had been confronted with more locking problems as storage for collection, restaurants, restrooms and fire-avoiding equipment. In addition, the library was not well-ventilated and without plenty of light. Based on these conditions, readers had experienced the uncomfortable environment when they entered the library. Especially in the busy day, there were a lot of noises from human voices and stepping sounds. In the end of all, the behavior of the readers in this library did not follow the rules designed by the library officers specifically. However, to most readers, they used the equipment and books in order to pass examination they faced. After their purposes were fulfilled, they would consider using the services and other books in their second choices. The exactly readers were not a lot, it made a space that readers in this library not just purely obeying the intention which was from the library officers or the government policy. On the whole of our analyzing result, readers owned their subjective to complete their personal objective, in this view of part, we would have one more peek of the readers as the real subjective in history.

La Thaïlande est un État unitaire et depuis 1892 son administration déconcentrée est assurée par la présence de gouverneurs provinciaux. Or, malgré de nombreuses attributions législatives, l'exercice des fonctions du chef de la province se heurte à plusieurs obstacles dans la pratique. A titre d'exemple, l'unité de commandement du gouverneur provincial était souvent contestée, les pouvoirs qui lui ont été délégués par les autorités centrales étaient inappropriés tant à sa fonction qu'à ses responsabilités. Ceci était une source de lenteur de l'administration provinciale dans son ensemble. Puis, comme la province ne pouvait pas bénéficier directement du budget provenant de l'État car la demande de budget provincial était effectuée au nom de la Direction, les projets réalisés sur place ne convenaient donc pas aux besoins des habitants locaux. Enfin, l'absence de coopération entre les fonctionnaires des différents organes dans la province contribuait alors aux chevauchements des travaux de ces organes et causait par la suite une perte de temps et d'argent pour l'État. Ainsi, lors de la réforme en 2001, le gouvernement de l'époque a introduit au niveau provincial le concept du gouverneur « CEO » et la méthode de la gestion d'intégration (MGI). Le chef de la province endosse alors le rôle du Chief Executive Officer (CEO), de ce fait ses pouvoirs ont été renforcés afin qu'il puisse prendre une décision rapide et efficace en réponse aux problèmes survenus dans sa province à l'instar des CEO dans leurs entreprises. Quant à la province, elle applique la MGI qui est une nouvelle façon de travailler visant à rendre de meilleurs services rendus à la population. / Thailand is a unitary state and since 1892 its deconcentrated administration is ensured by the presence of provincial governors. However, despite numerous attributions recognized by the laws, the provincial governor faces several obstacles in practice. For example, his Unity of Command was often challenged, the powers delegated to him by the central authorities were not only inappropriate to his function but also to his responsibilities. This was actually a source of slowness in provincial administration. Then, because the province could not directly benefit the budget from the State, as the process of demand for provincial budget was conducted on behalf of the Department, the projects that were carried out did not necessarily match up with local's need. Finally, the lack of cooperation between officials of different organs who work in the province contributed to an overlap of works and caused thereafter a waste of time and money to the State. Therefore, during the reform in 2001, the then government introduced the concept of "CEO" provincial governor and the system of "Province's Integrated Management - PIM". The provincial governor endorses hereupon the role of Chief Executive Officer (CEO), for this reason, his powers have been reinforced so that he can make a fast and effective decision in response to problems occurring in his province like the CEOs to their companies. As for the province, the system of PIM is applied and it is a new way of working which aims to provide a better service for the population.

Le sujet de cette thèse s'inscrit dans le cadre des systèmes tolérants aux défauts sous contraintes avec prise en considération de la dégradation des performances. L'objectif principal de ce travail consiste à considérer la gestion des références comme une partie intégrante du système de commande tolérant aux défauts. Dans la littérature, la plupart des méthodes actives de tolérance aux défauts supposent que le recouvrement du système nominal est toujours possible et que les performances nominales sont toujours atteignables. Cette condition est peu réaliste dans la pratique puisque plusieurs éléments empêchent le système reconfiguré de revenir à son mode de fonctionnement nominal. Dans le domaine industriel, l'ensemble des contraintes du système est un handicap majeur qui limite le fonctionnement nominal d'un système à des plages fonctionnelles bien définies. Ces plages fonctionnelles sont énormément réduites après l'apparition de certains défauts dits sévères et qui affectent généralement les actionneurs. Par conséquent, cette hypothèse de recouvrement des performances nominales dans le cas des systèmes sous contraintes limite l'ensemble des défauts traités par ces méthodes classiques à quelques défauts dits mineurs. Afin de remédier a ce problème, une architecture de reconfiguration structurée en deux niveaux est proposée. Le premier concerne les algorithmes classiques de reconfiguration en agissant sur un contrôleur reconfigurable, et le deuxième agit sur le module de gestion des références conçu à base d'un gouverneur de référence avec offset. La connaissance exacte du modèle en post-défaut nécessite un système de détection et diagnostic de défaut qui permet d'estimer l'amplitude de défaut, ce qui conduit à la synthèse d'un observateur adaptatif d'estimation de défaut à base de LMI. Afin de synchroniser le déroulement du processus FTC, deux indices ont été conçus. Le premier indice porte sur le mécanisme de décision permettant de sélectionner le/les niveau(x) de reconfiguration nécessaire(s) à l'accommodation du défaut. Le deuxième indice permet d'évaluer le niveau de dégradation du système « post-défaut ». Une dégradation de performance est toujours admise tant que les consignes de sécurité sont respectées / The subject of this thesis is part of fault tolerant control systems under constraints with consideration of performance degradation. The main objective of this work is to consider the reference management as an integral part of the fault tolerant control system. In the literature, the most active methods of fault tolerance imply that recovery of the nominal system is always possible and that performance ratings are still achievable. This requirement is unrealistic in practice because several factors prevent the system reconfigured back to its nominal operating mode. In industry, the set of system constraints is a major problem which limits the nominal operating of the system to defined functional ranges. These functional ranges are reduced dramatically after the occurrence of some faults known as severe faults that generally affect the capacity of actuators. Therefore, this assumption of nominal performance recovery in the case of systems under constraints limits the set of faults treated with these conventional methods to a few minor faults. To remedy this problem, architecture of reconfiguration structured in two levels is proposed. The first level concerns the conventional reconfiguration algorithms acting on a reconfigurable controller, and the second acts on the module of reference management based on a reference-offset governor. The exact knowledge of the post-fault model requires a fault detection and diagnosis system to estimate the magnitude of fault, which led to the synthesis of an adaptive observer based LMI for estimating fault. To synchronize the FTC process flow, two indices have been designed. The first index refers to the decision mechanism for selecting the reconfiguration level required for the accommodation of the fault. The second index used to evaluate the level of the degradation of the system "post-fault". The performance degradation is still allowed as long as safety instructions are respected

O Aeroporto Internacional Governador André Franco Montoro (GRU), São Paulo, depende inteiramente da água subterrânea para suprir sua demanda. Entretanto, a prática de extração excessiva, que aumenta continuamente para atender à demanda de um número cada vez maior de passageiros e às dificuldades envolvidas com a recarga natural do aqüífero, levou a Empresa Brasileira de Infraestrutura Aeroportuária (Infraero) a procurar outras fontes de abastecimento. Embora a busca de solução para o problema da escassez da água, passe pela opção de recarga gerenciada do aqüífero, a falta da experiência nacional nessa área restringe a tomada da decisão na adoção dessa prática no país. Objetivando contribuir com estudos de viabilidade técnica da recarga gerenciada de aqüíferos em geral e, em particular, do Aeroporto Internacional Governador André Franco Montoro, este trabalho tem o objetivo de verificar, em escala piloto, a capacidade do solo-aqüífero do aeroporto em tratar adequadamente o esgoto gerado localmente. Para atingir esse objetivo, uma área adequada foi selecionada entre as diversas avaliadas, para a construção de uma unidade piloto de recarga de aqüífero. No local selecionado, amostras indeformadas da camada não saturada foram coletadas, caracterizadas e, posteriormente, montadas em colunas experimentais especiais, pelas quais o esgoto foi infiltrado de maneira controlada. Como os resultados desta primeira fase experimental não foram adequadamente atendidos, foi decidido efetuar coletas de amostras indeformadas em uma segunda área do aeroporto, que indicou a existência de uma camada vadosa mais profunda, mas perfil de solo semelhante ao perfil anterior. Os ensaios de colunas foram efetuados com amostras de ambas as áreas, indicando que o solo superficial do aeroporto deverá ser eliminado, ou substituído por uma camada de areia grossa para permitir uma recarga gerenciada que permita a produção de águas com qualidade adequada para os usos preconizados. Os diferentes cenários utilizados nesta pesquisa envolveram a infiltração nas colunas de recarga com esgotos secundários produzidos no aeroporto, após passagem por duas lagoas de retenção, a infiltração do mesmo efluente tratado por um processo físico-químico de coagulação/floculação/sedimentação e pelo mesmo efluente das lagoas de retenção após tratamento por um sistema de membranas de ultrafiltração. Os resultados obtidos são considerados como resultados parciais, uma vez que toda a profundidade do aqüífero não foi utilizada e pelo fato de que, face às restrições acadêmicas vigentes o tempo disponível para a realização da pesquisa foi extremamente restringido. Entretanto, considera-se este trabalho como pioneiro, pelo fato dele se constituir na primeira pesquisa sobre recarga gerenciada no Brasil e, ainda, por fornecer subsídios teóricos e práticos para suportar outros estudos semelhantes que se farão necessários para compreender e promover a prática de recarga gerenciada de aqüíferos no Brasil. / The Governor André Franco Montoro International Airport, São Paulo, entirely depends on groundwater to meet its demand. However, excessive extraction practice which increase continuously in order to attend the demand of increasing number of passengers and the difficulty involved with natural recharge of its aquifer led the Federal Airport Administration Agency (Infraero) to search for other sources of water supply. Although the search for solution for water scarcity problem goes through managed aquifer recharge, lack of national experience in this area restricts decision making in adopting this practice in the country. Contributing to the technical feasibility studies of managed aquifer recharge in general and the Governor André Franco Montoro International Airport in particular, this research has the objective of verifying at the pilot scale level, the capacity of airport soil-aquifer in adequately treating wastewater generated locally. In order to reach this objective, an adequate location was selected within the alternatives evaluated for the construction of a pilot unit for aquifer recharge. Undeformed samples were collected from the unsaturated layer of the selected place, characterized and afterwards, recharged through special experimental columns with wastewater which was filtered in a controlled form. As the results of the first experimental phase were not adequately met, a decision was made to collect undeformed samples from a second location in the airport. The collection indicated the existence of deep unsaturated layer with the soil profile being similar to the profile of the soil layer from which the first samples were collected. The soil column tests were carried out with samples from both areas, indicating that superficial part of airport soil will be eliminated or substituted with a coarse sandy layer in order to permit a managed aquifer recharge which allows production of water that meets the quality of its required uses. Of the different scenarios verified in this research was infiltration of secondary wastewater produced at the airport through soil columns. Another was infiltration of wastewater after its pre-treatment by physicalchemical processes of coagulation/flocculation/sedimentation and still a third scenario, through pre-treatment of secondary effluent by ultrafiltration membrane. The results obtained are considered partial since the total aquifer depth was not used and the fact that academic restrictions limited excessively the time period of the research. However, considering this as a pioneer work, and the fact that it constitutes the first research about managed aquifer recharge in Brazil, and with it, bringing theoretical and practical contributions to support other similar studies which would be necessary in understanding and promoting managed aquifer recharge practice in Brazil.

- / In this thesis new advanced nonlinear control methods that solve the power system stabilization problem in a more efficient and integrated manner are considered. The proposed methods mainly concern with the primary level control of a power system that plays a central role in maintaining transient stability and obtaining a desired system performance. To this end, several new nonlinear control schemes mainly applicable on power system stabilizers (PSS) have been designed and extensively analyzed. For a theoretical assessment of the system operation the concepts of passivity and passivity margin are analyzed while the concept of Ω--passivity is introduced. Using partial feedback linearization and backstepping design techniques on suitable models of the system under consideration (power system) the Ω--passivity property of the system is proved. This property is further improved through the control in the closed-loop design. To this end, several control schemes are developed and a series of different theoretical problems have been solved on using simple output feedback and advanced nonlinear control methods like sliding mode control, adaptive control or a combination of them. A significant breakthrough has been achieved with the use of fuzzy techniques in these schemes yielding designs with combined advantages of both fuzzy and adaptive control methods. A detailed stability analysis, based on Lyapunov functions, has been used to prove that the proposed controllers guarantee either uniform ultimate boundedness or asymptotic stability for the closed-loop system. The proposed schemes are examined assuming that the system operates under parameter uncertainties as well as external disturbances. The theoretical analysis indicates that regulating some design parameters of the proposed controllers one can significantly improve the robustness and the disturbance attenuation capability of the system. Extensive simulations on a two machines infinite bus test system have been carried out to evaluate the effectiveness of the proposed schemes as these are applied on the PSS of each machine. Hard cases of three phase faults or significant power demand changes have been simulated. The simulation results show that the proposed nonlinear controllers enhance the damping of the electromechanical oscillations with respect to classical AVR/PSS and improve their robustness to parameter uncertainties and disturbance attenuation capability. Using similar techniques, speed governor controls (SGC) are also designed. An adaptive control scheme is proposed that ensures asymptotic stabilization of the closed-loop system as proved by standard Lyapunov techniques. Simulations are carried out for the one generator system connected to infinite bus. The simulation results confirm a significant improvement in the electromechanical oscillations damping compared to conventional speed governor controls. An important contribution of the thesis involves the coordination and management of the controls at the primary level. The design is carried out so that each control is not competing with the action of the other and it is cooperating to complement the action of the other. In this frame, first, the coordinated operation of the designed nonlinear power system stabilizers with the classical AVR/PSS is proposed. Particularly, the sequential operation of these controllers is considered in the following way: immediately after a fault, only the nonlinear controller operates but when the fault attenuates the classical AVR/PSS takes over. In this way, significant transient enhancement and voltage regulation after the large transients can be achieved. To implement this kind of operation a soft-switching logic from the one controller to the other is proposed by using a fuzzy logic mechanism to determine which controller will act each time period. In this way, it is avoided a discontinuous switching that can create a number of problems and may even lead to instabilities. The analysis and the simulation results confirm the validity of this approach since it is shown that the coordinated control scheme has an almost identical transient performance with the nonlinear controllers ensuring simultaneously the voltage regulation at the desired set-point. The same approach is used for the coordinated operation of FACTS with the excitation controllers. To this end, a static var compensator (SVC) controller is developed which, during a fault, acts to improve the transient stability. During the transient period, the SVC uses as inputs not the voltage at the connecting point but suitable signals from neighbor stations in order to contribute to the electromechanical oscillations damping; in the sequel, it returns to its normal operation maintaining the voltage level at the connecting point at a specified value. A soft switching scheme is also applied while signal transmission delays are taken into the account. The simulation results of a three phase short-circuit in a system with a single machine connected to infinite bus through a bus that has a SVC attached, indicate that this coordinated control scheme improves the transient stability even more (in comparison to the previous coordinated scheme). Finally, coordinated control logic is used for the design of both the speed governor control and the PSS. This is needed when the operation of the PSS cannot be considered completely independent and decoupled from the speed governor dynamics (in the case of fast valve operation). In this combined system a parallel design of both the SGC and the PSS ensures the uniform ultimate boundedness of the complete closed-loop system. Moreover, the use of continuous switching through fuzzy logic, as mentioned before, between these controllers and the classical AVR/PSS (for the excitation system) and a PID control (for the SGC) is proposed. The simulation results on the two machines infinite bus system clearly confirm the superiority of the coordinated control scheme with respect to the classical AVR/PSS excitation controllers and PID speed governor controllers. As a conclusion, new combined advanced nonlinear control schemes are analyzed and proposed for power systems. From the stability analysis and the simulation results it is clearly confirmed that the application of these nonlinear controls can be effectively improve the transient behavior as well as the robustness and disturbance attenuation of a power system. It is also proved that, without extreme cost, coordinated control schemes implemented through the proposed soft-switching techniques further enhance the transient and dynamic performance of the system.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study had as main objective to perform the modeling and analysis of transient stability of a typical electric power system. The second goal, also important, was to assess the feasibility of using ATP (Alternative Transients Program) as a computer tool for simulation of transient stability. The system focused here is comprised of nine busses with three generators, one hydraulic and the other two with thermal characteristics. All the system machines were equipped with voltage regulators and speed governor in ATP software. The technical issues studied here refer to the analysis of system stability after a disturbance, such as: three-phase short-circuit, load loss and generation outage. The results show that ATP software performs satisfactorily the transient stability analysis. This fact can also be proved by comparing the results obtained from ATP with those from simulations with PSAT (Power System Analysis Toolbox). For this purpose some adjustments were necessary in the graphical results since ATP works in time domain while PSAT program operates in the frequency domain. / Este trabalho teve como principal objetivo realizar a modelagem e a análise da estabilidade transitória de um sistema elétrico de potência típico. O segundo objetivo, também importante, consistiu em avaliar a viabilidade de se utilizar o ATP (Alternative Transients Program) como uma ferramenta computacional para simulação de estabilidade transitória. O sistema aqui enfocado é composto por nove barramentos com três unidades geradoras, uma com característica hidráulica e as outras duas com características térmicas. Todas as máquinas do sistema foram equipadas com reguladores de tensão e velocidade no programa ATP. As questões técnicas estudadas aqui se referem à análise da estabilidade do sistema após uma perturbação, sendo elas: falta trifásica, perda de carga e saída de geração. Os resultados mostram que o software ATP realiza satisfatoriamente a análise de estabilidade transitória. Este fato pode também ser comprovado pela comparação dos resultados obtidos com o ATP com aqueles provenientes de simulações com o PSAT (Power System Analysis Toolbox). Para este propósito foi necessário realizar alguns ajustes nos resultados gráficos já que ATP trabalha no domínio do tempo enquanto que o programa PSAT opera no domínio da frequência, tais como: transformação de alguns gráficos fornecidos pelo ATP em pu. / Mestre em Ciências