Teses / dissertações sobre o tema "Hvdc; mtdc"
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Junior, Rui Bertho. "Um novo algoritmo de proteção para redes HVDC multiterminais". Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-26042018-105556/.
Texto completo da fonteRecent progress regarding semiconductor devices used in AC/DC conversion led to the use of Voltage Source Converters (VSC) in High Voltage Direct Current (HVDC) power transmission systems. AN advantage of using VSCs it to simplify the creation of Multi-terminal HVDC (MTDC) networks. However, the severity of DC faults, combined with the converters vulnerability, requests the use of algorithms able to correctly identify fault occurrences in a short period of time. Therefore, this work aims to elaborate a new primary protection methodology that could be applied to HVDC systems, especially in MTDC networks. For this purpose, a detailed three terminals MTDC network has been modeled and, through extensive computational faulty simulations, DC current characteristics that are able to assist network protection methods were identified. By means of the wavelet transform, principal component analysis and genetic fuzzy systems, it was possible to develop a fast, reliable an selective non-unit protection for MTDC grids. Moreover, the proposed algorithm was implemented in hardware, emphasizing its applicability in actual systems. The proposed methodology was able to ensure selectivity, reliability and speed of operation, correctly identifying DC faults in less than 1.5 ms.
Sheridan, Caitríona Evelyn. "Assessment of HVDC technologies for an offshore MTDC grid". Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/38552.
Texto completo da fonteAkkari, Samy. "Contrôle d'un système multi-terminal HVDC (MTDC) et étude des interactions entre les réseaux AC et le réseau MTDC". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLC069/document.
Texto completo da fonteHVDC transmission systems are largely used worldwide, mostly in the form of back-to-back and point-to-point HVDC, using either thyristor-based LCC or IGBT-based VSC. With the recent deployment of the INELFE HVDC link between France and Spain, and the commissioning in China of a three-terminal HVDC transmission system using Modular Multilevel Converters (MMCs), a modular design of voltage source converters, the focus of the scientific community has shifted onto the analysis and control of MMC-based HVDC transmission systems. In this thesis, the average value models of both a standard 2-level VSC and an MMC are proposed and the most interesting difference between the two converter technologies -the control of the stored energy in the MMC- is emphasised and explained. These models are then linearised, expressed in state-space form and validated by comparing their behaviour to more detailed models under EMT programs. Afterwards, these state-space representations are used in the modelling of HVDC transmission systems, either point-to-point or Multi-Terminal HVDC (MTDC). A modal analysis is performed on an HVDC link, for both 2-level VSCs and MMCs. The modes of these two systems are specifed and compared and the independent control of the DC voltage and the DC current in the case of an MMC is illustrated. This analysis is extended to the scope of a 5-terminal HVDC system in order to perform a stability analysis, understand the origin of the system dynamics and identify the dominant DC voltage mode that dictates the DC voltage response time. Using the Singular Value Decomposition method on the MTDC system, the proper design of the voltage-droop gains of the controllers is then achieved so that the system operation is ensured within physical constraints, such as the maximum DC voltage deviation and the maximum admissible current in the power electronics. Finally, a supplementary droop "the frequency-droop control" is proposed so that MTDC systems also participate to the onshore grids frequency regulation. However, this controller interacts with the voltage-droop controller. This interaction is mathematically quantified and a corrected frequency-droop gain is proposed. This control is then illustrated with an application to the physical converters of the Twenties project mock-up
Nazari, Mohammad. "Control of DC voltage in Multi-Terminal HVDC Transmission (MTDC) Systems". Licentiate thesis, KTH, Elektriska energisystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-147551.
Texto completo da fonteQC 20140911
Akhter, Faheem. "Secure optimal operation and control of integrated AC/MTDC meshed grids". Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/19531.
Texto completo da fonteGonzalez-Torres, Juan Carlos. "Transient stability of high voltage AC-DC electric transmission systems". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS041.
Texto completo da fonteThe new policy frameworks adopted by national authorities has encouraged the large scale-integration of Renewable Energy Systems (RES) into bulk power systems. The large-scale integration of RES will have consequences on the electricity transmission system as it is conceived today, since the transmission of bulk power over long distances could lead the existing transmission systems to work close to their limits, thus decreasing their dynamic security margins. Therefore more complex transmissions systems are needed.Under this scenario, HVDC transmission systems raise as the most attractive solution for the reinforcement and improvement of existing AC networks, not only using point-to-point configurations, but also in a Multi-Terminal configuration. The introduction of HVDC transmission systems will eventually result in a hybrid high voltage AC/DC power system, which requires to be analyzed as a unique system in order to understand the interactions between the AC network and the DC grid.This thesis addresses the transient stability analysis of hybrid AC/DC electric transmission systems. More in particular, two questions sought to be investigated: What is the impact of a DC contingency on AC transient stability? How can we take advantage of the of DC transmission systems as control inputs in order to enhance AC transient stability?In the first part of this work, the mathematical models of the hybrid AC/DC grid are described as well as the necessary tools for the analysis of the system taking into account its nonlinear nature. Then, a thorough analysis of transient stability of the power system in the particular case of a DC fault and the execution of the corresponding protection strategies is done. As a complement, stability indicators and tools for sizing future MTDC grids in order to respect the constraints of existing protection strategies are proposed.The second part of the thesis addresses the control proposals for the modulation of power references of the HVDC transmission systems with the purpose of transient stability enhancement of the surrounding AC system. Firstly, we focus our study in the nonlinear control of point-to-point HVDC links in hybrid corridors. Fast power compensation, injection of damping power and injection of synchronizing power are identified as the mechanisms through which HVDC systems can improve stability margins.Finally, a control strategy for transient stability enhancement via active power injections of an MTDC grid is proposed. Using communication between the stations, the proposed decentralized control injects damping and synchronizing power between each pair of converters using only measurements at the converters level. The proposed implementation allows to fully use the available headroom of the converters by dealing with power limits in a decentralized way
Johansson, Henrik, e Lucas Tunelid. "Operation and Control of HVDC Grids". Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-293882.
Texto completo da fonteFör 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
Ahmadi, Seyedhesam, e Mehrdad Bahmani. "Reglering av effektflöde i HVDC-system genom centraliserad och distribuerad spänningskontroll i realtid". Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254267.
Texto completo da fonteShinoda, Kosei. "Contrôle et opération des réseaux HVDC multi-terminaux à base de convertisseurs MMC". Thesis, Ecole centrale de Lille, 2017. http://www.theses.fr/2017ECLI0017.
Texto completo da fonteThe scope of this thesis includes control and management of the Modular Multilevel Converter (MMC)-based Multi-Terminal Direct Current (MTDC).At first, our focus is paid on the internally stored energy, which is the important additional degree of freedom brought by the complex topology of MMC. In order to draw out the utmost of this additional degree of freedom, an in-depth analysis of the limits of this internally stored energy is carried out, and they are mathematically formulated.Then, this degree of freedom of the MMC is used to provide a completely new solution to improve the DC voltage dynamics. A novel control strategy, named Virtual Capacitor Control, is proposed. Under this control, the MMC behaves as if there were a physical capacitor whose size is adjustable. Thus, it is possible to virtually increase the equivalent capacitance of the DC grid to mitigate the DC voltage fluctuations in MTDC systems.Finally, the scope is extended to MMC-based MTDC grid. One of the crucial challenges for such system is to cope with a sudden loss of a converter station which may lead to a great variation of the system voltage. The voltage droop method is commonly used for this purpose. The analysis shows that the desired control action may not be exerted when the available headroom of the converter stations are insufficient. We thus propose a novel voltage droop control structure which permits to provide different actions depending on the sign of DC voltage deviation caused by the disturbance of system voltage as well as an algorithm that determines the droop parameters taking into account the operating point and the available headroom of each station
Bakhos, Gianni. "Gestion de la sécurité du réseau électrique AC & DC : évaluation et amélioration". Electronic Thesis or Diss., Université Grenoble Alpes, 2024. http://www.theses.fr/2024GRALT014.
Texto completo da fonteToday, the integration of renewable energies poses problems of congestion and uncertainty on the electricity network, given the intermittency and unpredictability of this type of energy. What's more, for reasons of profitability and efficiency, the power generated from renewables is transmitted in the form of High Voltage Direct Current (HVDC). A new concept has therefore emerged, that of merging HVDC interconnections into an existing meshed network, which will bring greater flexibility to the operation of the overall system. The result is a hybrid electricity transmission system with significant mutual interactions between the existing AC system and the integrated DC system. While the stability problems of the AC network have now been identified, those of the hybrid system still need to be studied, since the integration of rapidly controllable power converters could modify the behaviour of the entire system. As a result, this thesis project seeks to establish an innovative study encompassing the entire AC/DC hybrid system. This will focus on a security assessment that takes into account operational constraints and the ability of the system to reach a new equilibrium. In addition, this thesis will address the stabilisation challenges of the overall hybrid system. To this end, the assignments will consist of a preliminary study of the state of the art: what is the physical nature of the instability problems of the AC system? What types and ranges of disturbances should be considered for stability assessment? Finally, what modelling and control of the HVDC system? All of this will enable the development of an inclusive security assessment tool that takes into account different system control methods. An analysis will also be carried out to understand the influence of the parameters and control methods adopted. This will help us to implement a systematic means of control to improve network security and optimise power distribution across a Multi-Terminal DC network
Li, Yafang. "Etude d’un convertisseur DC-DC pour les réseaux haute tension à courant continu (HVDC) : modélisation et contrôle du convertisseur DC-DC modulaire multiniveaux (M2DC)". Thesis, Ecole centrale de Lille, 2019. http://www.theses.fr/2019ECLI0006/document.
Texto completo da fonteThis work is based on Multi Terminal Direct Current (MTDC) grids. In the MTDC grid, DC/DC converter stations are needed to connect different HVDC grids. A lot of DC/DC converters have been studied and developed, but are not suitable for high voltage and great power constraints. Therefore, the objective of this work is the study of a DC/DC converter for high voltage and great power applications. For the potentially HVDC applications, the volume and costs are major criteria. According to this, a high voltage and great power potential DC/DC converter is selected, which is the DC-DC Modular Multilevel Converter (M2DC). Focusing on the M2DC, the work proposes analyses in steady state and builds an average model for the converter. Based on the average model, the basic control algorithm for the converter is developed to validate the previous analysis. Since the thesis aims to use the existing L2EP Modular Multilevel Converter (MMC) to test the M2DC model and control, a design of the M2DC based on MMC is proposed. Finally, the M2DC HIL (Hardware In-the-Loop) simulations results are presented confirming previous analyses and allowing to go on to prototyping the M2DC on the base of the existing MMC
Freytes, Julian. "Analyse de stabilité en petit signaux des Convertisseurs Modulaires Multiniveaux et application à l’étude d'interopérabilité des MMC dans les Réseaux HVDC". Thesis, Ecole centrale de Lille, 2017. http://www.theses.fr/2017ECLI0022/document.
Texto completo da fonteThis thesis deals with the modeling and control of MMCs in the context of MTDC. The first objective is to obtain an MMC model in dq frame which can reproduce accurately the AC- and DC- interactions, while representing at the same time the internal dynamics which may interact with the rest of the system. This model is suitable to be linearized and to study its stability, among other linear techniques. Then, based on the developed dq model, different control strategies are developed based on the state-of-the-art on MMC controllers. Since the order of the system may be a limiting factor for studying MTDC grids with many MMCs, different reduced-order models are presented and compared with the detailed dq model. Finally, the developed MMC models with different controllers are used for the MTDC studies. The impact of the chosen controllers of each MMC is evaluated, highlighting the potential issues that may occur in multivendor schemes
"Hybrid AC-High Voltage DC Grid Stability and Controls". Doctoral diss., 2017. http://hdl.handle.net/2286/R.I.46197.
Texto completo da fonteDissertation/Thesis
Doctoral Dissertation Electrical Engineering 2017
Shyam, V. "Development Of An Application Specific Parallel Processing Real-Time System For MTDC System Control". Thesis, 1996. https://etd.iisc.ac.in/handle/2005/1755.
Texto completo da fonteShyam, V. "Development Of An Application Specific Parallel Processing Real-Time System For MTDC System Control". Thesis, 1996. http://etd.iisc.ernet.in/handle/2005/1755.
Texto completo da fonte