Dissertations / Theses on the topic 'High-voltage DC transmission'
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Luth, Thomas. "DC/DC converters for high voltage direct current transmission." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/24466.
Full textIkhide, Monday Aideloje. "DC line protection for multi-terminal High Voltage DC (HVDC) transmission systems." Thesis, Staffordshire University, 2017. http://eprints.staffs.ac.uk/4601/.
Full textGonzalez-Torres, Juan Carlos. "Transient stability of high voltage AC-DC electric transmission systems." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS041.
Full textThe 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
Robinson, Jonathan. "Efficiency and performance analysis of AC and DC grid based wind farms connected to a high voltage DC transmission line." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86959.
Full textUn réseau trans-canadien peut aider à intégrer l'énergie éolienne, qui s'étend sur une vaste zone géographique, en augmentant la capacité de transfert de puissance des lignes de transport et en réduisant les effets non-contrôlables des sources d'énergie renouvelable. L'utilisation de la technologie 'HVDC' peut réduire les coûts des longues lignes de transmission et aussi offrir d'autres avantages comme la réduction de l'empreinte géographique, une meilleure fiabilité, et la localisation des défauts. Toutefois, il n'y a pas de raccordements multi-terminaux HVDC en opération. Cette thèse propose deux méthodes de connexion d'un parc éolien à une ligne HVDC, utilisant des réseaux c.a. et c.c. Le rendement, les composantes requises et la performance transitoire des deux méthodes de connexion sont présentés. Une meilleure efficacité peut être obtenue avec le réseau c.a., mais en intégrant les éoliennes MT, l'efficacité du réseau c.c. est améliorée. Des études préliminaires démontrent que le réseau c.c. aide à une meilleure isolation d'un court-circuit dans le parc éolien qui pourrait se transmettre aux lignes HVDC. Les deux réseaux sont capables de réduire les effets d'un court-circuit, mais peuvent avoir des problèmes à demeurer en service sans déclenchement pour un défaut transitoire.
Fatokun, Folasade Okedoyin. "Corona ions from high voltage powerlines : production, effect on ambient particles, DC electric field and implications on human exposure studies." Thesis, Queensland University of Technology, 2008. https://eprints.qut.edu.au/20714/1/Folasade_Fatokun_Thesis.pdf.
Full textFatokun, Folasade Okedoyin. "Corona ions from high voltage powerlines : production, effect on ambient particles, DC electric field and implications on human exposure studies." Queensland University of Technology, 2008. http://eprints.qut.edu.au/20714/.
Full textTruong, Quoc-duy. "Use of expert systems in the preliminary design of high voltage DC point-to-point transmission systems." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60483.
Full textThe domain knowledge of the design of HVDC transmission systems is first discussed. This includes possible HVDC system configurations, cost of terminals, cost of transmission lines, cost of losses, and design expertise.
The details of converting the HVDC design domain knowledge into a structured knowledge base is demonstrated. Objects, properties, classes, and object-oriented programming techniques are introduced. Then, the implementation of rules and the architecture of a complete expert system including man-machine interface, external interface and data storage is presented.
A sample run from TRANSEPT-DC on an Intel 80386-based personal computer is provided to demonstrate the performance and the basic features of the HVDC expert system.
Diban, Bassel. "Life Estimation of HVDC Cables Subjected to Qualification Test Conditions." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18955/.
Full textShinoda, 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.
Full textThe 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
Otto, Abraham Johannes. "Direct current conductor corona modelling and metrology." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1497.
Full textENGLISH ABSTRACT: Prospects of up-rating existing high voltage direct current (HVDC) transmission schemes, as well as the conversion of existing alternating current (AC) to direct current (DC) lines and the development of new HVDC schemes in sub-Saharan Africa, have led to renewed interest in DC research. The radio interference (RI), audible noise (AN) and corona loss (CL) performance of HVDC transmission lines are critical factors when assessing the reliability of the line design. The RI performance is especially important when considering the successful transmission of the carrier signal of the power line carrier (PLC) system. The PLC system is the main form of communication between teleprotection devices on the Cahora Bassa HVDC scheme. The aim of the dissertation is to devise modelling as well as metrological techniques to characterise DC conductor corona. A particle-in-cell (PIC) computational code is developed to gain a better understanding of the physical processes that occur during corona events. The numerical code makes use of the charge simulation method (CSM) and nite element method (FEM) to solve for the Laplace and Poisson eld equations. Higher-order basis functions are implemented to obtain a more accurate solution to the Poisson equation. The computational tool yields insight into the mathematical models for the various ionization, attachment and electron avalanche processes that give rise to corona currents. Together with a designed and developed electrometer-type circuit, the numerical code assists the visualisation of the space charge particle dynamics that form in the electrode gap during corona events. The metrological techniques consider the wideband time domain (TD) as well as the frequency domain (FD) information of the measured corona pulses in the presence of noise. These are then compared to the narrowband CISPR standard measurements centred around 500kHz. The importance of impedance matching when attempting to derive a wideband excitation function is investigated. The TD measurements are quite distinct from the well-published FD measurements, and consider the pulse shape, pulse spectrum and pulse repetition rates. The use of three possible conductor corona test methods to study direct current conductor RI performance under both positive and negative polarities is investigated at high altitude in this dissertation. These include a small corona cage, a short test line and the Eskom Megawatt Park large outdoor corona cage. Derived wideband and narrowband monopolar DC RI excitation functions at 500kHz are consolidated with existing radio noise (RN) measurement protocols and prediction methods. The use of a corona cage to derive excitation functions for monopolar RI predictions is explored and it is shown that a small corona cage, due to the build-up of space charge in the small distance between the electrodes, cannot be used to predict the RI levels on HVDC transmission lines accurately. As a consequence of the physics, computational modelling and both frequency and time domain measurements, it is now possible to explain why a small cage system prevents the accurate RI prediction on transmission lines. The large outdoor corona cage and short test line RI performance predictions agree with existing empirical prediction formulas.
AFRIKAANSE OPSOMMING: Vooruitsigte van die opgradering van bestaande hoogspanningsgelykstroom transmissielyn skemas, asook die omkering van bestaande wisselstroom na gelykstroom lyne en die ontwikkeling van nuwe hoogspanningsgelykstroom skemas in sub-Sahara Afrika, het gelei to hernude belangstelling in gelykstroomnavorsing. Die korona-werkverrigting van hoogspanningsgelykstroom oorshoofselyne in terme van radiosteuring, hoorbare-geraas en koronaverliese is kritiese faktore om in aanmerking te neem wanneer die betroubaarheid van die lynontwerp geëvalueer word. Die radiosteuring-werkverrigting is veral van belang tot die suksesvolle oordrag van die kraglyndragolf draersein wat die hoof kommunikasievorm tussen beskermingstoerusting op die Cahora Bassa transmissielyn skema is. Die doel van hierdie proefskrif is om modellering- sowel as meettegnieke te ontwerp om gelykstroomgeleierkorona te karakteriseer. 'n Partikel-in-sel numeriese kode is ontwikkel om 'n beter begrip te verkry van die siese prosesse gedurende koronagebeure. Die numeriese kode maak gebruik van die lading-simulasiemetode, sowel as die eindige element metode om die Laplace en Poisson veldvergelykings op te los. Hoër-orde basisfunksies is geimplimenteer om 'n meer akkurate oplossing vir die Poisson vergelyking te verkry. Die numeriese kode bied insig tot die wiskundige modelle vir die verskeie ionisasie-, aanhegtings- en lawineprosesse wat lei tot koronastrome in die area om die hoogspanningsgeleier. Die numeriese kode, saam met 'n elektro-meter wat ontwerp en ontwikkel is, dra by tot die begrip van die ruimtelading partikeldinamika wat onstaan in die elektrodegaping gedurende koronagebeure. Die meettegnieke neem die wyeband tydgebied- en frekwensiegebiedinformasie van die koronapulse in ag in die teenwoordigheid van geraas. Dit word dan vergelyk met die nouband CISPR meetstandaard vir 'n frekwensie van 500kHz. Die belangrikheid van impedansie-aanpassing vir wyeband metings met die doel om opwekkingsfunksies af te lei, word ondersoek. Die tydgebiedmetings verskil van die algemene frekwensiegebiedmetings, en ondersoek die pulsvorm, -spektrum en -herhalingskoers. Die gebruik van drie moontlike koronageleier-toetsmetodes om gelykstroom radiosteurings-werkverrigting vir positiewe en negatiewe polariteite te bestudeer by hoë vlakke bo seespieël word ondersoek in die proefskrif. Dit sluit in 'n klein koronakou, 'n kort toetslyn en die Eskom Megawatt Park groot buitelug-koronakou. Afgeleide wye- en nouband monopolêre gelykstroom radiosteuring opwekkingsfunksies by 500kHz word gekonsolideer met bestaande radioruis metingsprotokolle en voorspellingsmetodes. Die gebruik van 'n koronakou om opwekkingsfunksies af te lei vir monopolêre radiosteuringvoorspellings is ondersoek en daar is gevind dat 'n klein koronakou nie gebruik kan word om radiosteuringvlakke op hoogspanningsgelykstroom transmissielyne akkuraat te voorspel nie. Dit is as gevolg van die opbou van ruimtelading in die klein elektrodegaping. Met behulp van die sika, numeriese modellering en beide die frekwensie- en tydgebiedmetings, is dit nou moontlik om te verklaar waarom die klein koronakou die akkurate radiosteuringvoorspellings op transmissielyne onmoontlik maak. Die groot buitelug-koronakou en kort toetslyn radiosteuringvoorspellings stem ooreen met bestaande empiriese voorspellings formules.
Ghossein, Layal. "Alimentation de circuit de commande rapprochée « Gate-drive » pour nouveaux convertisseurs de puissance haute tension." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI016.
Full textHVDC power transmission is the future of the electrical energy transmission network. The power converters (e.g. MMC) used in this network will be able to cope with voltages of hundreds of kV, making the power supply of the gate-drive devices in these converters challenging. It is then necessary to design solutions that guarantee the power supply of these gate-drives, while providing high voltage isolation. To do this, a circuit, based on the flyback principle, was developed. It is placed in parallel with a capacitor typically connected to a half-bridge circuit. It has an auto-start feature. This allows to supply the gate-drive as soon as a low voltage is applied to the input of the self-supply system. This is obtained by taking advantage of the normally-ON character of the JFET. In our prototype, the input voltage is 2 kV. High voltage JFETs of 2 kV and higher breakdown voltages are not yet available on the market. So, to achieve this high voltage capacity, a series of Normally-ON SiC JFETs controlled by a low voltage Si MOSFET (Super-cascode circuit) is used in the circuit. The developed circuit is able to supply 20 W at different floating potentials with output voltage regulated at 24 V and an efficiency close to 60%. The isolation problem is then solved using this solution
Гаврилюк, Ігор Миколайович, and Havryliuk Ihor. "Розробка проекту лінії електропередачі з вставкою постій¬ного струму." Master's thesis, ТНТУ імені Івана Пулюя, 2019. http://elartu.tntu.edu.ua/handle/lib/29562.
Full textIn the diploma paper deals with the possibility of combining non-synchronous power systems and systems with different frequency control standards. The purpose of the work is to develop a Kovel-Helm transmission line with a DC insert for the sale of electricity from Ukraine to Poland. Objects similar to those projected in this project can be implemented in other power grids, which will significantly reduce the size of AC synchronous networks, prevent or limit cascade outages, increase the efficiency of grids and the reliability of power systems.
ПЕРЕЛІК УМОВНИХ СКОРОЧЕНЬ.................................................................... 7 ВСТУП .................................................................................................................…8 1 АНАЛІТИЧНА ЧАСТИНА ...............................................................................13 1.1 Призначення вставок постійного струму......................................................13 1.2 ВВППС – основні характеристики системи .................................................15 1.3 Варіанти застосування ВВППС .....................................................................16 1.4 Керування потужністю ...................................................................................17 1.5 Поведінка ВВППС в умовах виходу з ладу системи змінного струму......18 1.6 Вплив підключеної мережі змінного струму на ВПС .................................19 1.7 Споживання реактивної потужності .............................................................21 1.8 Висновки до розділу .......................................................................................23 2 НАУКОВО-ДОСЛІДНА ЧАСТИНА................................................................24 2.1 Пріоритетні напрями діяльності магістрального електромережевого комплексу.........................................................................................................24 2.2 Заходи шодо зниження комерційних втрат електроенергії ........................28 2.3 Перспективи передачі електроенергії за допомогою постійного струму .30 2.4 Основні причини використання ППС в ОЕС України ................................32 2.5 Висновки до розділу .......................................................................................35 3 ТЕХНОЛОГІЧНА ЧАСТИНА ..........................................................................36 3.1 Вибір напруги ліній електропередач постійного струму............................36 3.2 Вибір схеми вставки постійного струму.......................................................40 3.3 Перетворення й регулювання струму конверторами ..................................41 3.4 Вибір тиристорів .............................................................................................44 3.5 Система захисту тиристорів від перенапруг та перевантажень .................48 3.6 Система охолодження тиристорних модулів ...............................................50 3.7 Визначення кількості тиристорів у вентильних групах перетворювача ...52 3.8 Висновки до розділу .......................................................................................54 4 ПРОЕКТНО-КОНСТРУКТОРСЬКА ЧАСТИНА ...........................................55 4.1 Вибір раціонального січення проводів .........................................................55 6 4.2 Розрахунок споживання реактивної енергії перетворювачами..................56 4.3 Усунення впливу вищих гармонік напруги й струму у схемі ВПС...........60 4.4 Розрахунок фільтрокомпенсуючого пристрою............................................65 4.5 Активні фільтри...............................................................................................71 4.6 Висновки до розділу .......................................................................................74 5 СПЕЦІАЛЬНА ЧАСТИНА................................................................................75 5.1 Вибір трансформатора ....................................................................................75 5.2 Компенсація реактивної потужності.............................................................78 5.3 Вибір місця під’єднання компенсаційних пристроїв ..................................81 5.4 Розрахунок потужності компенсаційних пристроїв ....................................81 5.5 Зменшення струму несиметрії у вставках постійного струму ...................84 5.6 Струм к.з. на шинах високої напруги трансформаторів .............................86 5.7 Вибір обладнання ............................................................................................87 5.8 Висновки до розділу .......................................................................................92 6 ОБГРУНТУВАННЯ ЕКОНОМІЧНОЇ ЕФЕКТИВНОСТІ..............................93 6.1 Критерії економічної ефективності енергетичного виробництва..............93 6.2 Визначення капітальних затрат .....................................................................94 6.3 Вартість електроенергії ..................................................................................95 6.4 Розрахунок економічної ефективності..........................................................98 7 ОХОРОНА ПРАЦІ ТА БЕЗПЕКА В НАДЗВИЧАЙНИХ СИТУАЦІЯХ ...100 7.1 Заходи безпеки при обслуговуванні електроустановок ............................100 7.2 Захист персоналу від впливу електричних і електромагнітних полів .....103 7.3 Захист персоналу підстанції від наведених напруг ...................................106 8 ЕКОЛОГІЯ........................................................................................................108 8.1 Актуальність охорони навколишнього середовища..................................108 8.2 Вплив на людину електромагнітного забруднення довкілля ...................108 8.3 Вплив магнітного поля повітряних ліній постійного струму високої і надвисокої напруги на навколишнє середовище.......................................110 ЗАГАЛЬНІ ВИСНОВКИ ДО ДИПЛОМНОЇ РОБОТИ ...................................112 ПЕРЕЛІК ПОСИЛАНЬ .......................................................................................113
Jovcic, Dragan. "Control of high voltage DC and flexible AC transmission systems." 1999. http://hdl.handle.net/2292/272.
Full textLIN, ZHI-MING, and 林志明. "A Simulation Study to Offshore Wind Farms That Use High Voltage DC Transmission System." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/463z2t.
Full text國立中正大學
電機工程研究所
107
The development of Taiwan's offshore wind power is one of the government’s policy objectives. However, a large-scale offshore wind power integration is bound to pose great challenges to the operation of existing power systems. How to maintain the voltage is one of the important issues. This thesis studies the integration of offshore wind farms with 2.4 GW and 6.5 GW into the Taiwan power system in 2024 and 2025, respectively. This thesis investigates the system voltage under different operating scenarios and analyzes the voltage control using the VSC-HVDC or HVAC transmission. In the simulation process, the software of the power system analysis, PSS/E, is used to complete the equivalent wind farm model, the models of HVAC and VSC-HVDC transmission systems, and the model of reactive power compensation component. Based on the simulation results, it can be highlighted that the importance of voltage control, the advantages of HVDC transmission, and the necessity of establishing a wind farm equivalent model after a large scale of offshore wind farms is integrated into the Taiwan power system.
Stringfellow, Jake David. "Control and modulation of the modular multilevel converter under unbalanced cell power conditions." Thesis, 2020. http://hdl.handle.net/1959.13/1438193.
Full textThis thesis presents a control and modulation scheme for the Modular Multilevel Converter under unbalanced power conditions. The modular multilevel converter is a relatively new converter topology and since its introduction has garnered interest in both literature and industry for its applications in High Voltage DC transmission. Whilst the majority of the published work has been for traditional applications for the converter, there has been recent interest in new applications for the converter. This includes the use of the converter as a photovoltaic interface, where power sources are directly connected to each converter cell. To maintain operation under a variety of operating conditions, new control and modulation schemes may be required. The thesis presents an energy balancing model based on the production of a number of controlled circulating current components in the converter. This energy model allows for the decoupling of the power generation in each arm, resulting in independent control of the arm voltages, and the compensation for large unbalanced power production across the converter. A model based deadbeat current controller is developed to control the converters output and circulating currents. A new heuristic model predictive control based modulation scheme is proposed to allow for the operation of each converter cell at separate references while generating the desired arm voltages. This is achieved while providing a balance between switching transitions and the spread of cell voltages from their references in each converter arm. Simulation and experimental results are presented to validate the performance and functionality of the proposed control and modulation scheme. It was found that the control scheme provides for the ability to maintain stable converter operation with large varied powers across all converter cells while maintaining balanced output powers and low device switching frequencies.
Shyam, 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.
Full textDastgeer, Faizan. "Direct current distribution systems for residential areas powered by distributed generation." Thesis, 2011. https://vuir.vu.edu.au/19383/.
Full text