Дисертації з теми "Power system operating modes"
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1
Nguyen, Van Liem. "Modeling and control coordination of power systems with FACTS devices in steady-state operating mode." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0036.
Повний текст джерелаАнотація:
This thesis is devoted to the development of new models for a recently-implemented FACTS (flexible alternating current transmission system) device, the unified power flow controller (UPFC), and the control coordination of power systems with FACTS devices in steady-state operating mode. The key objectives of the research reported in the thesis are, through online control coordination based on the models of power systems having FACTS devices, those of maximising the network operational benefit and restoring system static security following a disturbance or contingency. Based on the novel concept of interpreting the updated voltage solutions at each iteration in the Newton-Raphson (NR) power-flow analysis as dynamic variables, the thesis first develops a procedure for representing the unified power flow controllers (UPFCs) in the steady-state evaluation. Both the shunt converter and series converter control systems of a UPFC are modeled in their dynamical form with the discrete time variable replaced by the NR iterative step in the power-flow analysis. The key advantage of the model developed is that of facilitating the process of UPFC constraint resolution during the NR solution sequence. Any relative priority in control functions pre-set in the UPFC controllers is automatically represented in the power-flow formulation. Although the developed UPFC model based on the dynamic simulation of series and shunt converter controllers is flexible and general, the number of NR iterations required for convergence can be large. Therefore, the model is suitable mainly for power system planning and design studies. For online control coordination, the thesis develops the second UPFC model based on nodal voltages. The model retains all of the flexibility and generality of the dynamic simulation-based approach while the number of iterations required for solution convergence is independent of the UPFC controller dynamic responses. Drawing on the constrained optimisation based on Newtons method together with the new UPFC model expressed in terms of nodal voltages, a systematic and general method for determining optimal reference inputs to UPFCs in steady-state operation is developed. The method is directly applicable to UPFCs operation with a high-level line optimisation control (LOC) for maximising the network operational benefit. By using a new continuation technique with adaptive parameter, the algorithm for solving the constrained optimisation problem extends substantially the region of convergence achieved with the conventional Newtons method. Having established the foundation provided by the comprehensive models developed for representing power systems with FACTS devices including the UPFC, the research, in the second part, focuses on real-time control coordination of power system controllers, with the main purpose of restoring power system static security following a disturbance or contingency. At present, as the cost of phasor measurement units (PMUs) and wide-area communication network is on the decrease, the research proposes and develops a new secondary voltage control where voltages at all of the load nodes are directly controlled, using measured voltages.
2
Bai, Wenshuai. "DC Microgrid optimized energy management and real-time control of power systems for grid-connected and off-grid operating modes." Thesis, Compiègne, 2021. http://www.theses.fr/2021COMP2586.
Повний текст джерелаАнотація:
Le travail de recherche de cette thèse se concentre sur l’élaboration de deux modes de fonctionnement du microréseau à savoir : mode connecté au réseau, mode hors réseau comprenant les modes îloté et isolé. Le problème de la défaillance du réseau en mode connecté au réseau et la faible fiabilité de l'alimentation électrique en mode hors réseau doivent être résolues. Ainsi, le but de cette thèse est de proposer un microréseau DC combinant à la fois les avantages du mode connecté au réseau et ceux du mode isolé. On obtient ainsi un microréseau DC qu’on peut qualifier de complet. Le microréseau DC complet contient les sources d'énergie renouvelables, le stockage et le réseau public, et les sources de secours sont utilisées pour réduire le délestage. Dans ce microréseau DC, un système de supervision est proposé dans le but de gérer le flux des puissances. La gestion de la puissance en temps réel dans la couche opérationnelle du système de supervision permet de maintenir l'équilibre de puissance. Dans la couche d'optimisation du système de supervision, l'optimisation journalière est proposée afin de minimiser le coût d'exploitation global. Les résultats de la simulation montrent que le microréseau DC complet peut minimiser les coûts d'exploitation. Ensuite, le système de supervision prend en compte l'efficacité dynamique du convertisseur pour résoudre le problème lié à la qualité de la puissance du microréseau qui peut être dégradée à cause de la tension instable du bus DC. Les résultats de la simulation montrent que la prise en compte de l'efficacité dynamique du convertisseur dans la couche opérationnelle du système de supervision permet de réduire les fluctuations de la tension du bus DC. En ce qui concerne l'importance de la prédiction PV pour l'optimisation de la veille, deux modèles de prédiction sont étudiés et comparés pour donner une puissance de prédiction PV précise. Les résultats montrent que les deux modèles ont presque les mêmes résultatsThis thesis focus on the research of the DC microgrid following two operation models: grid-connected mode, and off-grid mode including the islanded and isolated modes. The aim of this thesis is to propose a DC microgrid combining the advantages of the grid-connected or the off-grid mode, which named full DC microgrid. ln the full DC microgrid, the renewable energy sources, storage, and public grid are included, and the back-up sources also applied to reduce the load shedding. ln the full DC microgrid, a supervisory system is proposed to manage the power. The real-time power management in the operational layer of the supervisory system can keep the power balance. ln the optimization layer of the supervisory system, the day-ahead optimization is proposed to achieve the global minimal operation cost. The simulation results show that the full DC microgrid combines both advantages of the grid-connected and the off-grid mode to minimize the operating cost. Then, the supervisory system considers the dynamic efficiency of the converter to solve the problem that the power quality of the microgrid is degraded due to the unstable DC bus voltage caused by the inaccurate power control. The simulation results show that considering the dynamic efficiency of the converter in the operational layer of the supervisory system, the fluctuation of the DC bus voltage can be reduced. Regarding the importance of the PV prediction for the day-ahead optimization, two prediction modes are studied and compared to give a robust PV prediction power. The results are that the two models almost have the same results
3
Гречин, Юрій Олегович. "Модернізація та адаптація розрахункової моделі УРМЕС-2М для моделювання і розрахунків режимів електричних мереж". Master's thesis, Київ, 2018. https://ela.kpi.ua/handle/123456789/25636.
Повний текст джерелаАнотація:
Магістерська дисертація складається з пояснювальної записки та графічного матеріалу. Пояснювальна записка містить у собі 188 сторінках машинописного тексту формату А4, містить 94 рисунків та 24 таблиць, 20 джерел використаної літератури. Графічна частина складається з 9 аркушів технічних креслень у форматі А1.
В дисертації розглянуто і запропоновано варіант удосконалення універсального лабораторного стенду УРМЕС-2М, розроблено та проведено цикл лабораторних робіт за допомогою програмного комплексу Matlab та проведено моделювання монтажної плати електронно-цифрового генератора, розроблено стартап-проект, розглянуто та пораховано релейний захист шунтувального реактору, розглянуто питання охорони праці при використанні лабораторного стенду.The master's dіssertatіon consіsts of an explanatory note and graphіc materіal. The explanatory note contaіns 188 pages of typewrіtten A4 text, contaіns 94 fіgures and 24 tables, 20 sources of used lіterature. Graphіc part consіsts of 9 pіeces of technіcal drawіngs іn the format A1. Іn the dіssertatіon the varіant of perfectіon of the unіversal laboratory stand URMES-2M was consіdered and proposed, the cycle of laboratory works was developed and conducted wіth the help of the Matlab software package and the sіmulatіon of the electronіc-dіgіtal generator cіrcuіt board was carrіed out, a startup project has been developed, a relay protection for the shunt reactor has been considered and taken into account, the issues of labor protection with the use of a laboratory stand are considered.
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Welsch, Manuel. "Enhancing the Treatment of Systems Integration in Long-term Energy Models." Doctoral thesis, KTH, Energisystemanalys, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-134100.
Повний текст джерелаАнотація:
Securing access to affordable energy services is of central importance to our societies. To do this sustainably, energy systems design should be – amongst other things – environmentally compliant and reconcile with the integrated management of potentially limiting resources. This work considers the role for so-called 'Smart Grids' to improve the delivery of energy services. It deals with the integration of renewable energy technologies to mitigate climate change. It further demonstrates an approach to harmonise potentially conflicting energy, water and land-use strategies. Each presents particular challenges to energy systems analysis. Computer aided models can help identify energy systems that most effectively meet the multiple demands placed on them. As models constitute a simple abstraction of reality, it is important to ensure that those dynamics that considerably impact results are suitably integrated. In its three parts, this thesis extends long-term energy system models to consider improved integration between: (A) supply and demand through Smart Grids; (B) timeframes by incorporating short-term operating constraints into long-term models; and (C) resource systems by linking multiple modelling tools. In Part A, the thesis explores the potential of Smart Grids to accelerate and improve electrification efforts in developing countries. Further, a long-term energy system model is enhanced to investigate the Smart Grid benefits associated with a closer integration of supply, storage and demand-side options. In Part B, the same model is extended to integrate flexibility requirements. The benefits of this integration are illustrated on an Irish case study on high levels of wind power penetrations. In Part C, an energy model is calibrated to consider climate change scenarios and linkages with land-use and water models. This serves to assess the implications of introducing biofuels on the small island developing state of Mauritius. The thesis demonstrates that too weak integration between models and resource systems can produce significantly diverging results. The system configurations derived may consequently generate different – and potentially erroneous – policy and investment insights.Säker och prisvärd tillgång till energitjänster är en central fråga för dagens samhällen. För att tillgodose samhällen med hållbara energitjänster bör energisystemen designas för att – bland annat – möta de miljömässiga kraven samt hantera potentiellt begränsade resurser. Den här avhandlingen undersöker de ”smarta” elnätens roll för bättre tillhandahållande av energitjänster. Avhandlingen behandlar integration av förnybar energiteknik för minskad klimatpåverkan samt demonstrerar ett tillvägagångssätt för att förena potentiellt motstridiga energi-, vatten- och markanvändningsstrategier. Dessa uppvisar särskilda utmaningar i energisystemanalyser. Datorstödda modeller kan användas för att identifiera energisystem som på effektivast sätt möter samhällets krav. Datorstödda modeller är, per definition, förenklingar av verkligheten och det är därför viktigt att säkerställa en korrekt representation av det verkliga systemets dynamik. Den här avhandlingen förstärker energisystemmodeller för långsiktsprognoser utifrån tre aspekter: förbättra integrationen av (A) tillgång och efterfrågan genom smarta elnät; (B) olika tidsaspekter genom att inkludera kortsiktiga operativa begränsningar; samt (C) resurssystem genom att sammanlänka olika modelleringsverktyg. I del A utforskades de smarta elnätens potential för att förbättra elektriska system i utvecklingsländer. En befintlig energisystemmodell förstärktes för att behandla smarta elnät och kan därmed fånga fördelarna förknippade med energilagring och energianvändning. I del B utvidgades en energisystemmodell för långsiktsprognoser med flexibilitet för kortsiktiga operativa begränsningar. En fallstudie fokuserad på ett vindkraftsdominerat irländskt elnät genomfördes för att demonstrera fördelarna av modellutvecklingen. I del C kalibrerades en energisystemmodell för att ta klimatscenarier i beaktande samt energisystemets kopplingar till markanvändning och vattenresurssystem. En fallstudie fokuserad på Mauritius energisystem genomfördes för att undersöka konsekvenserna av en potentiell introducering av biobränslen. Avhandlingen demonstrerar att undermålig integration av energimodeller och resurssystem kan leda till avsevärda avvikelser i resultaten. Slutsatser som dras utifrån dessa resultat kan därmed leda till vitt skilda – och potentiellt felaktiga – underlag för investeringar och energipolitiska rekommendationer.
QC 20131118
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Heidari, Shayan. "Economic Modelling of Floating Offshore Wind Power : Calculation of Levelized Cost of Energy." Thesis, Mälardalens högskola, Industriell ekonomi och organisation, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-36130.
Повний текст джерелаАнотація:
Floating offshore wind power is a relatively new technology that enables wind turbines to float above the sea level, tied by anchors at the seabed. The purpose of this work is to develop an economic model for the technology in order to calculate the total cost of a planned wind farm. Cost data are retrieved from reports and academic journals available online. Based on these data, a model in Microsoft Excel is developed which calculates the Levelized cost of energy (LCOE) for floating wind power plants as a function of several input values. As an addition to this model, financing offshore projects are described using literature study and by doing interviews with three major companies, currently investing in offshore wind. As a result, the model allows the user to calculate Capital expenditures, Operating expenditures and LCOE for projects at any given size and at any given site. The current LCOE for a large floating offshore wind farm is indicated to be in the range of 138-147 £/MWh. The outline from interviews was that today there is no shortage of capital for funding wind projects. However, in order to attract capital, the governmental regulatory of that market has to be suitable since it has a crucial impact on price risks of a project.
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Snowdon, David Computer Science & Engineering Faculty of Engineering UNSW. "Operating system directed power management." Awarded By:University of New South Wales. Computer Science & Engineering, 2010. http://handle.unsw.edu.au/1959.4/44747.
Повний текст джерелаАнотація:
Energy is a critical resource in all types of computing systems from servers, where energy costs dominate data centre expenses and carbon footprints, to embedded systems, where the system's battery life limits the device's functionality. In their efforts to reduce the energy use of these system's hardware manufacturers have implemented features which allow a reduced energy consumption under software control. This thesis shows that managing these settings is a more complex problem than previously considered. Where much (but not all) of the previous academic research investigates unrealistic scenarios, this thesis presents a solution to managing the power on varying hardware. Instead of making unrealistic assumptions, we extract a model from empirical data and characterise that model. Our models estimate the effect of different power management settings on the behaviour of the hardware platform, taking into account the workload, platform and environmental characteristics, but without any kind of a-priori knowledge of the specific workloads being run. These models encapsulate a system's knowledge of the platform. We also developed a \emph{generalised energy-delay} policy which allows us to quickly express the instantaneous importance of both performance and energy to the system. It allows us to select a power management strategy from a number of options. This thesis shows, by evaluation on a number of platforms, that our implementation, Koala, can accurately meet energy and performance goals. In some cases, our system saves 26\% of the system-level energy required for a task, while losing only 1\% performance. This is nearly 46\% of the dynamic energy. Taking advantage of all energy-saving opportunities requires detailed platform, workload and environmental information. Given this knowledge, we reach the exciting conclusion that near optimal power management is possible on real operating systems, with real platforms and real workloads.
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Mallangi, Siva Sai Reddy. "Low-Power Policies Based on DVFS for the MUSEIC v2 System-on-Chip." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-229443.
Повний текст джерелаАнотація:
Multi functional health monitoring wearable devices are quite prominent these days. Usually these devices are battery-operated and consequently are limited by their battery life (from few hours to a few weeks depending on the application). Of late, it was realized that these devices, which are currently being operated at fixed voltage and frequency, are capable of operating at multiple voltages and frequencies. By switching these voltages and frequencies to lower values based upon power requirements, these devices can achieve tremendous benefits in the form of energy savings. Dynamic Voltage and Frequency Scaling (DVFS) techniques have proven to be handy in this situation for an efficient trade-off between energy and timely behavior. Within imec, wearable devices make use of the indigenously developed MUSEIC v2 (Multi Sensor Integrated circuit version 2.0). This system is optimized for efficient and accurate collection, processing, and transfer of data from multiple (health) sensors. MUSEIC v2 has limited means in controlling the voltage and frequency dynamically. In this thesis we explore how traditional DVFS techniques can be applied to the MUSEIC v2. Experiments were conducted to find out the optimum power modes to efficiently operate and also to scale up-down the supply voltage and frequency. Considering the overhead caused when switching voltage and frequency, transition analysis was also done. Real-time and non real-time benchmarks were implemented based on these techniques and their performance results were obtained and analyzed. In this process, several state of the art scheduling algorithms and scaling techniques were reviewed in identifying a suitable technique. Using our proposed scaling technique implementation, we have achieved 86.95% power reduction in average, in contrast to the conventional way of the MUSEIC v2 chip’s processor operating at a fixed voltage and frequency. Techniques that include light sleep and deep sleep mode were also studied and implemented, which tested the system’s capability in accommodating Dynamic Power Management (DPM) techniques that can achieve greater benefits. A novel approach for implementing the deep sleep mechanism was also proposed and found that it can obtain up to 71.54% power savings, when compared to a traditional way of executing deep sleep mode.Nuförtiden så har multifunktionella bärbara hälsoenheter fått en betydande roll. Dessa enheter drivs vanligtvis av batterier och är därför begränsade av batteritiden (från ett par timmar till ett par veckor beroende på tillämpningen). På senaste tiden har det framkommit att dessa enheter som används vid en fast spänning och frekvens kan användas vid flera spänningar och frekvenser. Genom att byta till lägre spänning och frekvens på grund av effektbehov så kan enheterna få enorma fördelar när det kommer till energibesparing. Dynamisk skalning av spänning och frekvens-tekniker (såkallad Dynamic Voltage and Frequency Scaling, DVFS) har visat sig vara användbara i detta sammanhang för en effektiv avvägning mellan energi och beteende. Hos Imec så använder sig bärbara enheter av den internt utvecklade MUSEIC v2 (Multi Sensor Integrated circuit version 2.0). Systemet är optimerat för effektiv och korrekt insamling, bearbetning och överföring av data från flera (hälso) sensorer. MUSEIC v2 har begränsad möjlighet att styra spänningen och frekvensen dynamiskt. I detta examensarbete undersöker vi hur traditionella DVFS-tekniker kan appliceras på MUSEIC v2. Experiment utfördes för att ta reda på de optimala effektlägena och för att effektivt kunna styra och även skala upp matningsspänningen och frekvensen. Eftersom att ”overhead” skapades vid växling av spänning och frekvens gjordes också en övergångsanalys. Realtidsoch icke-realtidskalkyler genomfördes baserat på dessa tekniker och resultaten sammanställdes och analyserades. I denna process granskades flera toppmoderna schemaläggningsalgoritmer och skalningstekniker för att hitta en lämplig teknik. Genom att använda vår föreslagna skalningsteknikimplementering har vi uppnått 86,95% effektreduktion i jämförelse med det konventionella sättet att MUSEIC v2-chipets processor arbetar med en fast spänning och frekvens. Tekniker som inkluderar lätt sömn och djupt sömnläge studerades och implementerades, vilket testade systemets förmåga att tillgodose DPM-tekniker (Dynamic Power Management) som kan uppnå ännu större fördelar. En ny metod för att genomföra den djupa sömnmekanismen föreslogs också och enligt erhållna resultat så kan den ge upp till 71,54% lägre energiförbrukning jämfört med det traditionella sättet att implementera djupt sömnläge.
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Furrer, Travis C. (Travis Clay) 1976. "Power aware embedded operating system design." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/86470.
Повний текст джерелаАнотація:
Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.Includes bibliographical references (p. 73-74).
by Travis C. Furrer.
S.B.and M.Eng.
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Tverdal, Martin. "Operating system directed power reduction on EFM32." Thesis, Norwegian University of Science and Technology, Department of Computer and Information Science, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-11026.
Повний текст джерелаАнотація:
Power consumption has become a major concern of embedded systems.Currently FreeRTOS wastes a power waking up regularly to keep track of time.In this work FreeRTOS is modified to sleep when there is no work for the CPU to be done.Timekeeping while sleeping is done by a low frequency oscillator, consuming very little power.Drivers for peripherals have been developed, in order to optimise power consumption even more. Battery life time has been increased from 56 hours to 1867 hours for a simple self made benchmark.The goal is to get the changes into the official FreeRTOS distribution, but it has not been accepted yet.However, a customer of Energy Micro has started to develop an application based on this design.
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Whitlock, Rogers Jr. "Identification of Power System Stability Using Relevant Modes." ScholarWorks@UNO, 2011. http://scholarworks.uno.edu/td/1384.
Повний текст джерелаАнотація:
The purpose of this investigation is to identify appropriate location of capacitor banks and sources of reactive power by studying power system stability in the vicinity of system equilibrium states. The locations for reactive power sources are determined by identifying those modes of the system that participate most in the system behavior in general and in dictating the final state of the system after experiencing faults or disturbances. To identify the relevant modes of the system that participate most in the system dynamic, we shall make use of modal and participation analysis for different system conditions. We also apply modal and participation analysis to a system in order to identify the components of greatest impact that result in the most efficient system control. The ideas developed in this study are used to analyze and identify weak boundaries of the IEEE 39- Bus system that contribute to the system’s instability.
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Liu, Xinghua, and 刘兴华. "Power system operation integrating clean energy and environmental considerations." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43085866.
Повний текст джерела
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Yuan, Wei. "Reliable Power System Planning and Operations through Robust Optimization." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5807.
Повний текст джерелаАнотація:
In this dissertation, we introduce and study robust optimization models and decomposition algorithms in order to deal with the uncertainties such as terrorist attacks, natural disasters, and uncertain demand that are becoming more and more signicant in power systems operation and planning. An optimal power grid hardening problem is presented as a defender-attacker-defender (DAD) sequential game and solved by an exact decomposition algorithm. Network topology control, which is an eective corrective measure in power systems, is then incorporated into the defender-attacker-defender model as a recourse operation for the power system operator after a terrorist attack. Computational results validate the cost-eectiveness of the novel model. In addition, a resilient distribution network planning problem (RDNP) is proposed in order to coordinate the hardening and distributed generation resource placement with the objective of minimizing the distribution system damage under uncertain natural disaster events. A multi-stage and multi-zone based uncertainty set is designed to capture the spatial and temporal dynamics of a natural disaster as an extension to the N-K worst-case network interdiction approach. Finally, a power market day-ahead generation scheduling problem, i.e., robust unit commitment (RUC) problem, that takes account of uncertain demand is analyzed. Improvements have been made in achieving a fast
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Nair, Nirmal-Kumar. "Incorporating voltage security into the planning, operation and monitoring of restructured electric energy markets." Texas A&M University, 2004. http://hdl.handle.net/1969.1/3199.
Повний текст джерелаАнотація:
As open access market principles are applied to power systems, significant changes
are happening in their planning, operation and control. In the emerging marketplace,
systems are operating under higher loading conditions as markets focus greater attention
to operating costs than stability and security margins. Since operating stability is a basic
requirement for any power system, there is need for newer tools to ensure stability and
security margins being strictly enforced in the competitive marketplace. This dissertation
investigates issues associated with incorporating voltage security into the unbundled
operating environment of electricity markets. It includes addressing voltage security in
the monitoring, operational and planning horizons of restructured power system.
This dissertation presents a new decomposition procedure to estimate voltage
security usage by transactions. The procedure follows physical law and uses an index
that can be monitored knowing the state of the system. The expression derived is based
on composite market coordination models that have both PoolCo and OpCo transactions,
in a shared stressed transmission grid. Our procedure is able to equitably distinguish the
impacts of individual transactions on voltage stability, at load buses, in a simple and fast
manner.
This dissertation formulates a new voltage stability constrained optimal power flow
(VSCOPF) using a simple voltage security index. In modern planning, composite power
system reliability analysis that encompasses both adequacy and security issues is being
developed. We have illustrated the applicability of our VSCOPF into composite
reliability analysis.
This dissertation also delves into the various applications of voltage security index.
Increasingly, FACT devices are being used in restructured markets to mitigate a variety
of operational problems. Their control effects on voltage security would be
demonstrated using our VSCOPF procedure. Further, this dissertation investigates the
application of steady state voltage stability index to detect potential dynamic voltage
collapse.
Finally, this dissertation examines developments in representation, standardization,
communication and exchange of power system data. Power system data is the key input
to all analytical engines for system operation, monitoring and control. Data exchange
and dissemination could impact voltage security evaluation and therefore needs to be
critically examined.
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Abrahamsson, Lars. "Optimal Railroad Power Supply System Operation and Design : Detailed system studies, and aggregated investment models." Doctoral thesis, KTH, Elektriska energisystem, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-107037.
Повний текст джерелаАнотація:
Railway power supply systems (RPSSs) differ mainly from public power systems from that the loads are moving. These moving loads are motoring trains. Trains can also be regenerating when braking and are then power sources. These loads consume comparatively much power, causing substantial voltage drops, not rarely so big that the loads are reduced. By practical reasons most RPSSs are single-phase AC or DC. Three-phase public grid power is either converted into single-phase for feeding the railway or the RPSS is compartmentalized into separate sections fed individually from alternating phase-pairs of the public grid. The latter is done in order not to overload any public grid phase unnecessarily much. This thesis summarizes various ways of optimally operating or designing the railway power supply system. The thesis focuses on converter-fed railways for the reasons that they are more controllable, and also has a higher potential for the future. This is also motivated in a literature-reviewing based paper arguing for the converter usage potential. Moreover, converters of some kind have to be used when the RPSS uses DC or different AC frequency than the public grid. The optimal operation part of this thesis is mainly about the optimal power flow controls and unit commitments of railway converter stations in HVDC-fed RPSSs. The models are easily generalized to different feeding, and they cope with regenerative braking. This part considers MINLP (mixed integer nonlinear programming) problems, and the main part of the problem is non-convex nonlinear. The concept is presented in one paper. The subject of how to model the problem formulations have been treated fully in one paper. The thesis also includes a conference article and a manuscript for an idea including the entire electric train driving strategy in an optimization problem considering power system and mechanical couplings over time. The latter concept is a generalized TPSS (Train Power Systems Simulator), aiming for more detailed studies, whereas TPSS is mainly for dimensioning studies. The above optimal power flow models may be implemented in the entire electric train driving strategy model. The optimal design part of this thesis includes two aggregation models for describing reduction in train traffic performance. The first one presented in a journal, and the second one, adapted more useful with different simulation results was presented at a conference. It also includes an early model for optimal railway power converter placements. The conclusions to be made are that the potential for energy savings by better operation of the railway power system is great. Another conclusion is that investment planning models for railway power systems have a high development potential. RPSS planning models are computationally more attractive, when aggregating power system and train traffic details.QC 20121206
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Tumay, Mehmet. "The performance of power system protection under transient operating conditions." Thesis, University of Strathclyde, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322064.
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Chan, K. W. "A power system simulator to model the transient mode of operation of the (UK) national supergrid in real-time." Thesis, University of Bath, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332307.
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陳卓雄。 and Chuk-hung Chan. "Design and evaluation of active power factor correction circuit operation in discontinuous inductor current mode." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31220344.
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Chan, Chuk-hung. "Design and evaluation of active power factor correction circuit operation in discontinuous inductor current mode /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B2062315X.
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Тевяшев, А. Д., О. І. Матвієнко, and Г. В. Никитенко. "Stochastic Model of Operating Modes of a Group of Artesian Wellsin Water Supply Systems." Thesis, ХНУРЕ, 2020. https://openarchive.nure.ua/handle/document/16411.
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Chan, Chi-yiu, and 陳志銚. "The application of insurance theory to power system operating reserve market." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B3124399X.
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GREENHALGH, ANGELA BARBOSA. "VOLTAGE STABILITY ENHANCEMENT IN THE OPERATION OF POWER SYSTEMS THROUGH AN OPTIMIZATION MODEL." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1998. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=8943@1.
Повний текст джерелаАнотація:
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORMuito tem sido feito para que se possa entender os mecanismos que levam o sistema a uma situação de instabilidade de tensão e até mesmo ao colapso, assim como também para se suprir a necessidade de ferramentas analíticas capazes de prever e avaliar a proximidade do colapso de tensão em sistemas complexos, identificando as áreas susceptíveis à instabilidade de tensão. Uma vez detectada a inconveniente proximidade a uma condição de operação susceptível ao colapso de tensão, é necessária a identificação de grandezas-chave e sensibilidades, que forneçam entendimento suficiente, para ajudar no desenvolvimento de metodologias para reforçar as condições de estabilidade de tensão. Tendo isto como objetivo, este trabalho trata do problema de reforço da estabilidade de tensão através da mudança do perfil de tensão, utilizando como ferramenta computacional um algoritmo de otimização. Há no sistema variáveis de controle que interferem diretamente no perfil de tensão, tais como, tensão base nos geradores e compensadores, taps de transformadores, e capacitadores e reatores usados para compensação de potência reativa. Entretanto, quando as condições de estabilidade já se encontram deterioradas, as ações de controle do perfil de tensão podem levar a resultados insatisfatórios, podendo mesmo agravar o problema. Neste trabalho é apresentada uma metodologia, baseada em algoritmo de otimização, que fornece a lista de variáveis de controle mais eficientes para o reforço da estabilidade de tensão, e a direção em que os controles devem ser acionados. O interesse é obter um ponto de operação viável mais robusto, do ponto de vista de estabilidade de tensão, e não necessariamente um ponto de operação ótimo.
Much hás been done for the understanding of the voltage instabilitu mechanisms and to supply the necessity of analytical tools, which should have the ability tom predict and evaluate the proximity of voltage collapse in complex systems, identifying the critical áreas susceptible to voltage istability. Once the inconvenient proximity to an operating condition susceptible to voltage collapse is identified, it is necessary to look for the key factors and sensitivities that provide the reinforcement of the voltage stability conditions. Having it as a goal, this work treats the problem of reinforcing the voltage stability conditions, through changes of the voltage profile, using an optimal algorithm as a computational tool. There are control variables in the system which directly interfere on the voltage profile, such as, voltage set point on generators and compensators, transformer taps, capacitors and reactors. However, when the voltage stability conditions are already deteriorated, the voltage profile control actions may lead to unsatisfactory results, and may even aggravate the problem. It is presented a methodology based on an optimal, that provides the list of the most efficient control variables for the reinforcement of voltage stability, and the corresponding direction of movement. The search is for a feasible operating point, more robust in relation to voltage stability, and not necessarily for an optimal operating point.
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Yin, Changjie. "Impact of diesel generator operating modes on standalone DC microgrid and control strategies implying supercapacitor." Thesis, Compiègne, 2018. http://www.theses.fr/2018COMP2411/document.
Повний текст джерелаАнотація:
La nature intermittente et aléatoire des sources renouvelables, telles que le photovoltaïque et l’éolien, nécessite un complément de stockage, tel une batterie et un système de secours énergétique, tel un générateur diesel, en particulier dans un système autonome. En ce qui concerne le générateur diesel, il a besoin d'un certain temps pour démarrer et il ne peut pas donner immédiatement la puissance nécessaire, en raison de son comportement dynamique. Alors, la qualité de l'énergie est abaissée pendant cette période en raison du manque de puissance. Par conséquent, pendant la période de démarrage du générateur diesel, un supercondensateur est suggéré pour équilibrer la puissance en raison de sa réponse rapide et de sa densité de puissance élevée. Une stratégie de contrôle de puissance est proposée pour réaliser la coordination entre le générateur diesel et le supercondensateur. La simulation et les résultats expérimentaux montrent que la stratégie de contrôle proposée est capable de réguler la tension du bus continu dans des limites acceptables et d’alimenter la charge pendant la sous production d'énergie renouvelable ou lors d'augmentation de la demande de la charge. De plus, le supercondensateur peut également être utilisé pour surmonter les limites de stockage électrochimique telles que son état de charge et son courant maximal. Ainsi, cette thèse propose le contrôle de puissance en temps réel pour un micro réseau continu avec un système hybride photovoltaïque-batterie-supercondensateur-diesel, visant à répondre à la demande de puissance de charge avec fiabilité et à stabiliser de la tension du bus continu. La simulation et les résultats expérimentaux montrent également que la stratégie de contrôle améliore les performances dynamiques et statiques du micro réseau continu pour différentes conditions de fonctionnement. De plus, afin de minimiser le coût énergétique du groupe diesel, le coût du carburant et la consommation de carburant sont analysés à travers plusieurs tests expérimentaux. Par conséquent, la valeur optimale de sa production d'énergie est déduite et appliquée dans une nouvelle stratégie de gestion de la puissance est proposée. Cette stratégie peut atteindre l'objectif de maximiser l'utilisation de l'énergie photovoltaïque et de prendre en compte la caractéristique de démarrage lent et le coût énergétique du générateur diesel. Les simulations et expérimentations sont réalisées en utilisant des données photovoltaïques réelles pour illustrer les performances et le comportement du système hybride. Les résultats obtenus vérifient l'efficacité de cette stratégie. De plus la comparaison avec la stratégie de gestion de la puissance précédente, dans laquelle le coût d’énergie du générateur diesel n'est pas pris en compte, démontre que la nouvelle stratégie de gestion peut réduire le coût total du système de puissance à courant continu hybrideThe intermittent and random nature of renewable sources, such as photovoltaic and wind turbine, asks for the complement of storage, such as battery and back-up energy, such as diesel generator, especially in a standalone power system. Concerning the diesel generator, it needs some time to start up and cannot immediately offer the needed power, due to its dynamic behavior. Hence, the power quality is lowered down during this period because of the shortage of power. Therefore, during the period of the diesel generator starting up, a supercapacitor is suggested to compensate the power balance because of its fast response and high power density. A power control strategy is proposed to achieve the coordination between diesel generator and supercapacitor. Both simulation and experimental results show that the proposed control strategy is able to regulate the DC bus voltage within the acceptable limits and supplying the load during the renewable power under generation or load step-increase situations. In addition, the supercapacitor can be also used to overcome the electrochemical storage limits like its state of charge and maximum current. So, this thesis proposes the real time power control for a hybrid photovoltaic-battery-supercapacitor-diesel generator DC microgrid system, aiming to meet the load power demand with reliability and stabilizing the DC bus voltage. Both simulation and experimental results show that the designed control strategy improves the DC microgrid dynamic and static performances under different operating conditions. Furthermore, in order to minimize the diesel generator energy cost, the fuel cost and fuel consumption are analysed through several experimental tests. Therefore, the optimal value of its power generation is deduced and applied in a newly proposed energy management strategy. This strategy can achieve the goal of maximizing the utilization of photovoltaic energy and taking into account the slow start-up characteristic and energy cost of diesel generator. Both simulation and experimental studies are carried out by using the real photovoltaic data to illustrate the performance and the behavior of the hybrid system. The obtained results verify the effectiveness of this strategy. Furthermore, the comparison with the previous energy management strategy, in which the diesel generator energy cost is not considered, demonstrates that the newly proposed energy management strategy can reduce the total cost of the hybrid DC power system
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Backeman, Peter, and Erik Gustafsson. "Demonstrating the Effects of Power Management on a Real-time Operating System." Thesis, Uppsala University, Department of Information Technology, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-129477.
Повний текст джерелаАнотація:
This thesis is part of the GEODES project, dealing with the issues of power optimization, e.g. how to make a systems lifetime longer, at the cost of the quality of the performance, this is called system degradation.
The objective for this project was develop an application to monitor and visualize the effects of power management (controlled system degradation to minimize power consumption). With such software it is possible to demonstrate the possibilities of so called energy aware systems.
During the project two scenarios were investigated and implemented, one is a simple state-based monitor. This monitor application can observe and visualize the effects of power management on a computer system. It shows that by utilizing system degradation, the lifetime of a system can be prolonged.
The other scenario consists of a prototype for a firefighter coordinator application. It allows a rescue leader to observe firefighters at an emergency scene. This application can interact with the power management, by requesting a desired life time of a hand-held device carried by the firefighter. This shows that these techniques can be utilized without knowledge of the underlying power management software.
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Raak, Fredrik. "Investigation of Power Grid Islanding Based on Nonlinear Koopman Modes." Thesis, KTH, Elektriska energisystem, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-136834.
Повний текст джерелаАнотація:
To view the electricity supply in our society as just sockets mountedin our walls with a constant voltage output is far from the truth. Inreality, the power system supplying the electricity or the grid, is themost complex man-made dynamical system there is. It demands severecontrol and safety measures to ensure a reliable supply of electric power.Throughout the world, incidents of widespread power grid failures havebeen continuously reported. The state where electricity delivery to customersis terminated by a disturbance is called a blackout. From a stateof seemingly stable operating conditions, the grid can fast derail intoan uncontrollable state due to cascading failures. Transmission linesbecome automatically disconnected due to power flow redirections andparts of the grid become isolated and islands are formed. An islandedsub-grid incapable of maintaining safe operation conditions experiencesa blackout. A widespread blackout is a rare, but an extremely costlyand hazardous event for society.During recent years, many methods to prevent these kinds of eventshave been suggested. Controlled islanding has been a commonly suggestedstrategy to save the entire grid or parts of the grid from a blackout.Controlled islanding is a strategy of emergency control of a powergrid, in which the grid is intentionally split into a set of islanded subgridsfor avoiding an entire collapse. The key point in the strategy is todetermine appropriate separation boundaries, i.e. the set of transmissionlines separating the grid into two or more isolated parts.The power grid exhibits highly nonlinear response in the case oflarge failures. Therefore, this thesis proposes a new controlled islandingmethod for power grids based on the nonlinear Koopman Mode Analysis(KMA). The KMA is a new analyzing technique of nonlinear dynamicsbased on the so-called Koopman operator. Based on sampled data followinga disturbance, KMA is used to identify suitable partitions of thegrid.The KMA-based islanding method is numerically investigated withtwo well-known test systems proposed by the Institute of Electrical andElectronics Engineers (IEEE). By simulations of controlled islanding inthe test system, it is demonstrated that the grid’s response following afault can be improved with the proposed method.The proposed method is compared to a method of partitioning powergrids based on spectral graph theory which captures the structural propertiesof a network. It is shown that the intrinsic structural propertiesof a grid characterized by spectral graph theory are also captured by theKMA. This is shown both by numerical simulations and a theoreticalanalysis.
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Seyhan, Tolga Han. "An Intertemporal And Spatial Network Model For Turkish Energy System." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608594/index.pdf.
Повний текст джерелаАнотація:
Turkey, as a recent signatory to the United Nations Framework Convention on Climate Change (UNFCCC) has to adopt policies to restrict greenhouse gas emissions at a time when energy demand is increasing rapidly. We report on an intertemporal, spatial network model representing the energy system that seeks to address the difficult trade-offs involved. We compute and optimal mix of fuels and technologiesconsidering efficiencies and investments in generation and transmission. The model allows analysis of emissions and investment decisions to attain set targets. Extensions allowing the study of dependency on fossil fuels and imports are also discussed.
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Amakali, Simaneka. "Development of models for short-term load forecasting using artificial neural networks." Thesis, Cape Peninsula University of Technology, 2008. http://hdl.handle.net/20.500.11838/1070.
Повний текст джерелаАнотація:
Thesis submitted in fulfilment of the requirements for the degree
Master of Technology: Discipline Electrical Engineering
in the Faculty of Engineering
at the Cape Peninsula University of Technology
2008Optimal daily operation of electric power generating plants is very essential for any power utility organization to reduce input costs and possibly the prices of electricity in general. For a fossil fuel – fired power plant for example, the benefits of power generation optimalization (i.e. generate what is reasonably required) extends even to environmental issues such as the subsequent reduction in air pollution. Now to generate “what is reasonably required” one needs forecast the future electricity demands. Because power generation relies heavily on the electricity demand, the consumers are also practically speaking required to wisely manage their loads to consolidate the power utility’s optimal power generation efforts. Thus, for both cases, accurate and reliable electric load forecasting systems are absolutely required. To date, there are numerous forecasting methods developed primarily for electric load forecasting. Some of these forecasting techniques are conventional and often less favoured. To get a broad picture of the problem at hand, a literature survey was first conducted to identify possible drawbacks of the existing forecasting techniques including the conventional one. Artificial neural networks (ANNs) approach for short-term load forecasting (STLF) has been recently proposed by a majority of researchers. But there still is a need to find optimal neural network structures or convenient training approach that would possibly improve the forecasting accuracy. This thesis developed models for STLF using ANNs approach. The evolved models are intended to be a basis for real forecasting application. These models are tested using actual load data of the Cape Peninsula University of Technology (CPUT) Bellville campus reticulation network and weather data to predict the load of the campus for one week in advance. The models were divided into two classes: first, forecasting the load for a whole week at once was evaluated, and then hourly models were studied. In both cases, the inclusion of weather data was considered. The test results showed that the hour-by-hour approach is more suitable and efficient for a forecasting application. The work suggests that incremental training approach of a neural network model should be implemented for on-line testing application to acquire a universal final view on its applicability. Keywords – power system operations, load forecasting, artificial neural networks, training mode, accuracy
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Staron, Daniel Lee. "Concrete deterioration inspection system for extending the operating life of nuclear power plants." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/45197.
Повний текст джерелаАнотація:
This study has evaluated the degradation processes which will potentially affect the reinforced concrete structures of a nuclear power generation facility during and beyond its original design life. This task was undertaken in consideration of the feasibility of extending the life of nuclear power plants beyond their current license expiration dates. Following the identification of deterioration mechanisms which are expected to occur, an inspection system was developed to correctly assess and document the condition of the reinforced concrete components during their service life.
Twenty-eight out of thirty-nine possible degradation modes are deemed likely to affect Surry’s reinforced concrete structures. The majority of these modes are visually evident in their incipient stages. Currently available nondestructive testing methods were assessed to determine their applicability to detect modes which are not visually evident or to determine the extent of deterioration due to other modes. It was found that many nondestructive testing methods are currently lacking in reliability, portability, or ease of application. Consequently, the developed inspection program is based primarily on visual inspections performed by qualified inspectors. This report was prepared under the authority of Virginia Power Company in conjunction with the Surry Unit One life extension study.
It is the conclusion of this report that reinforced concrete degradation will in no way impair the usefulness or safety of the concrete structures of a nuclear facility during the 40 year design life provided actions are taken to implement a concrete inspection program similar to that which is described within. This program will allow the detection of potentially critical situations thereby directing the maintenance and repair activities necessary to insure the feasibility of extended life.Master of Science
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Simmons, Justin French. "Complete and Exact Small Signal Analysis of DC-to-DC Switched Power Converters Under Various Operating Modes and Control Methods." PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/195.
Повний текст джерелаАнотація:
A method to obtain the exact control-to-output and input-to-output transfer functions for switched DC-to-DC pulse-width modulated power converters is applied to different combinations of operating conditions such as continuous conduction mode (CCM), discontinuous conduction mode (DCM), and discontinuous voltage mode (DVM) and methods of control such as normal voltage mode (NVM), current programming mode (CPM), and V-squared control. The majority of these combinations have not previously had their transfer functions of interest derived to the accuracy provided by the method. The derivation of the method is covered, and the results from its application are verified by simulation. The simulation method is also justied and proposed as an improvement to the methods used by simulation engines for switched mode power supply design such as SIMPLIS.
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Sun, Haibin. "Integrated Modeling of Electric Power System Operations and Electricity Market Risks with Applications." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14103.
Повний текст джерелаАнотація:
Through integrated modeling of power system operations and market risks, this thesis addresses a variety of important issues on market signals modeling, generation capacity scheduling, and electricity forward trading. The first part of the thesis addresses a central problem of transmission investment which is to model market signals for transmission adequacy. The proposed system simulation framework, combined with the stochastic price model, provides a powerful tool for capturing the characteristics of market prices dynamics and evaluating transmission investment. We advocate the use of an AC power flow formulations instead since it allocates transmission losses correctly and reveals the economic incentives of voltage requirements. By incorporating reliability constraints in the market dispatch, the resulting market prices yield incentives for market participants to invest in additional transmission capacity. The second part of the thesis presents a co-optimization modeling framework that incorporates market participation and market price uncertainties into the capacity allocation decision-making problem through a stochastic programming formulation. Optimal scenario-dependent generation scheduling strategies are obtained. The third part of the thesis is devoted to analyzing the risk premium present in the electricity day-ahead forward price over the real-time spot price. This study establishes a quantitative model for incorporating transmission congestion into the analysis of electricity day-ahead forward risk premium. Evidences from empirical studies confirm the significant statistical relationship between the day-ahead forward risk premium and the shadow price premiums on transmission flowgates.
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Cvetkovic, Igor. "Modeling and Control of Voltage-Controlling Converters for Enhanced Operation of Multi-Source Power Systems." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/85850.
Повний текст джерелаАнотація:
The unconventional improvements in the power electronics field have been the primary reason for massive deployment of renewable energy sources in the electrical power grid over the past several decades. This needed trend, together with the increasing penetration of micro-, and nano- grids, is bringing significant improvements in system controllability, performance, and energy availability, but is fundamentally changing the nature of electronically-interfaced sources and loads, altering their conventionally mild aggregate dynamics, and inflicting low- and high- frequency dynamic interactions that never before existed at this magnitude. This problem is not restricted only to the grid; modern electronic power distribution systems built for airplanes, ships, electric vehicles, data-centers, and homes, comprise dozens, even hundreds of power electronics converters, produced by different manufacturers, who provide very limited details on converters' dynamic behavior - distinctiveness that has the highest impact on how two converters, or converter and a system interact. Consequently, substantial dispersion of power electronics into the future grid will significantly depend on engineers' capability to understand how to model and dynamically control power flow and subsystem interactions. It is therefore essential to continue developing innovative methods that allow easier system-level modeling, continuous monitoring of dynamic interactions, and advanced control concepts of power electronics converters and systems.
The dissertation will start with a "black box" approach to modeling of three-phase power electronics converters, introducing a method to remove source and load dynamics from in-situ measured terminated frequency responses. It will be then shown how converter, itself, can perform an online stability assessment knowing its own unterminated dynamics, and being able to measure all terminal immittances. The dissertation will further advance into an approach to control power electronics converters based on the electro-mechanical duality with synchronous machines, and end with selected examples of system-level operation, where small-signal instability in multi-source power systems can be mitigated using this concept.Ph. D.
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Lingga, Marwan Mossa. "Developing a Hierarchical Decision Model to Evaluate Nuclear Power Plant Alternative Siting Technologies." PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/2943.
Повний текст джерелаАнотація:
A strong trend of returning to nuclear power is evident in different places in the world. Forty-five countries are planning to add nuclear power to their grids and more than 66 nuclear power plants are under construction.
Nuclear power plants that generate electricity and steam need to improve safety to become more acceptable to governments and the public. One novel practical solution to increase nuclear power plants' safety factor is to build them away from urban areas, such as offshore or underground. To date, Land-Based siting is the dominant option for siting all commercial operational nuclear power plants. However, the literature reveals several options for building nuclear power plants in safer sitings than Land-Based sitings.
The alternatives are several and each has advantages and disadvantages, and it is difficult to distinguish among them and choose the best for a specific project. In this research, we recall the old idea of using the alternatives of offshore and underground sitings for new nuclear power plants and propose a tool to help in choosing the best siting technology.
This research involved the development of a decision model for evaluating several potential nuclear power plant siting technologies, both those that are currently available and future ones. The decision model was developed based on the Hierarchical Decision Modeling (HDM) methodology. The model considers five major dimensions, social, technical, economic, environmental, and political (STEEP), and their related criteria and sub-criteria. The model was designed and developed by the author, and its elements' validation and evaluation were done by a large number of experts in the field of nuclear energy.
The decision model was applied in evaluating five potential siting technologies and ranked the Natural Island as the best in comparison to Land-Based, Floating Plant, Artificial Island, and Semi-Embedded plant.
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SILVA, ALEXANDRE MOREIRA DA. "TWO-STAGE ROBUST OPTIMIZATION MODELS FOR POWER SYSTEM OPERATION AND PLANNING UNDER JOINT GENERATION AND TRANSMISSION SECURITY CRITERIA." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2014. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=24754@1.
Повний текст джерелаАнотація:
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Recentes apagões em todo o mundo fazem da confiabilidade de sistemas de potência, no tocante a contingências múltiplas, um tema de pesquisa mundial. Dentro desse contexo, se faz importante investigar métodos eficientes de proteger o sistema contra falhas de alguns de seus componentes, sejam elas dependentes e/ou independentes de outras falhas. Nesse sentido, se tornou crucial a incorporação de critérios de segurança mais rigorosos na operação e planejamento de sistemas de potência. Contingências múltiplas são mais comuns e desastrosas do que falhas naturais e independentes. A principal razão para isso reside na complexidade da estabilidade dinâmica de sistemas de potência. Além disso, o sistema de proteção que opera em paralelo ao sistema de distribuição não é livre de falhas. Portanto, interrupções naturais podem causar contingências em cascata em decorrência do mau funcionamento de mecanismos de proteção ou da instabilidade do sistema elétrico como um todo. Nesse contexto, se dá a motivação pela busca de critérios de segurança mais severos como, por exemplo, o n - K, onde K pode ser maior do que 2. Nesse trabalho, o principal objetivo é incorporar o crtitério de segurança geral n-K para geração e transmissão em modelos de operação e planejamento de sistemas de potência. Além de interrupções em geradores, restrições de rede, bem como falhas em linhas de transmiss˜ao também são modeladas. Esse avanço leva a novos desafios computacionais, para os quais formulamos metodologias de solução eficientes baseadas em decomposição de Benders. Considerando operação, duas abordagens são apresentadas. A primeira propõe um modelo de otimização trinível para decidir o despacho ótimo de energia e reservas sob um critério de segurançaa n - K. Nessa abordagem, a alta dimensionalidade do problema, por contemplar restrições de rede, bem como falhas de geradores e de linhas de transmissão, é contornada por meio da implícita consideração do conjunto de possíveis contingências. No mesmo contexto, a segunda abordagem leva em conta a incerteza da carga a ser suprida e a correlação entre demandas de diferentes barras. Considerando planejamento de expansão da transmissão, outro modelo de otimização trinível é apresentado no intuito de decidir quais linhas de transmissão, dentro de um conjunto de candidatas, devem ser construídas para atender a um critério de segurança n - K e, consequentemente, aumentar a confiabilidade do sistema como um todo. Portanto, as principais contribuições do presente trabalho são as seguintes: 1) modelos de otimização trinível para considerar o critério de segurança n - K em operação e planejamento de sistemas de potência, 2) consideração implícita de todo o conjunto de contingências por meio de uma abordagem de otimização robusta ajustável, 3) otimização conjunta de energia e reserva para operação de sistemas de potência, considerando restrições de rede e garantindo a entregabilidade das reservas em todos os estados pós-contingência considerados, 4) metodologias de solução eficientes baseadas em decomposição de Benders que convergem em passos finitos para o ótimo global e 5) desenvolvimento de restrições válidas que alavancam a eficiência computacional. Estudos de caso ressaltam a eficácia das metodologias propostas em capturar os efeitos econômicos de demanda nodal correlacionada sob um critério de segurançaa n - 1, em reduzir o esfor¸co computacional para considerar os critérios de seguran¸ca convencionais n-1 e n-2 e em considerar critérios de segurança mais rigorosos do que o n - 2, um problema intratável até então.
Recent major blackouts all over the world have been a driving force to make power system reliability, regarding multiple contingencies, a subject of worldwide research. Within this context, it is important to investigate efficient methods of protecting the system against dependent and/or independent failures. In this sense, the incorporation of tighter security criteria in power systems operation and planning became crucial. Multiple contingencies are more common and dangerous than natural independent faults. The main reason for this lies in the complexity of the dynamic stability of power systems. In addition, the protection system, that operates in parallel to the supply system, is not free of failures. Thus, natural faults can cause subsequent contingencies (dependent on earlier contingencies) due to the malfunction of the protection mechanisms or the instability of the overall system. These facts drive the search for more stringent safety criteria, for example, n - K, where K can be greater than 2. In the present work, the main objective is to incorporate the joint generation and transmission general security criteria in power systems operation and planning models. Here, in addition to generators outages, network constraints and transmission lines failures are also accounted for. Such improvement leads to new computational challenges, for which we design efficient solution methodologies based on Benders decomposition. Regarding operation, two approaches are presented. The first one proposes a trilevel optimization model to decide the optimal scheduling of energy and reserve under an n - K security criterion. In such approach, the high dimensionality curse of considering network constraints as well as outages of generators and transmission assets is withstood by implicitly taking into account the set of possible contingencies. The second approach includes correlated nodal demand uncertainty in the same framework. Regarding transmission expansion planning, another trilevel optimization model is proposed to decide which transmission assets should be built within a set of candidates in order to meet an n - K security criterion, and, consequently, boost the power system reliability. Therefore, the main contributions of this work are the following: 1) trilevel models to consider general n - K security criteria in power systems operation and planning, 2) implicit consideration of the whole contingency set by means of an adjustable robust optimization approach, 3) co-optimization of energy and reserves for power systems operation, regarding network constraints and ensuring the deliverability of reserves in all considered post-contingency states, 4) efficient solution methodologies based on Benders decomposition that finitely converges to the global optimal solution, and 5) development of valid constraints to boost computational efficiency. Case studies highlight the effectiveness of the proposed methodologies in capturing the economic effect of nodal demand correlation on power system operation under an n - 1 security criterion, in reducing the computational effort to consider conventional n-1 and n-2 security criteria, and in considering security criteria tighter than n - 2, an intractable problem heretofore.
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Wu, Shuang. "A generalized inverter control method for a variable speed wind power system under unbalanced operating conditions." Cleveland, Ohio : Cleveland State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=csu1274902463.
Повний текст джерелаАнотація:
Thesis (M.S.)--Cleveland State University, 2010.Abstract. Title from PDF t.p. (viewed on June 3, 2010). Includes bibliographical references (p. 118-120). Available online via the OhioLINK ETD Center and also available in print.
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Baral, Bishwas. "Directional Comparison Bus Protection Using Superimposed Partial Operating Current Characteristics." ScholarWorks@UNO, 2019. https://scholarworks.uno.edu/td/2584.
Повний текст джерелаАнотація:
Various directional comparison bus protection methods including widely used superimposed directional element method need to have both voltages and currents from all feeders connected to the zone of protection to find the direction of current for detecting a bus fault or a line fault. The purpose of the thesis is to present a new technique for directional comparison bus protection to discriminate a bus fault from line fault and normal condition. The new technique, which is implementing superimposed directional element method to modify partial operating current characteristics (POC) method to superimposed POC (SPOC) method, does not use voltages from feeders, hence capacitor voltage transformers (CVTs) are no longer needed in the zone of protection. The proposed technique was implemented in 4-bus and IEEE 14-bus test system and was tested using different fault cases including CT saturation and high impedance fault. The proposed technique, SPOC method was compared with POC method with both methods implemented in same test systems and tested with same fault cases. The results show that the proposed technique is successful to detect bus faults with high accuracy and high speed.
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Dam, Quang Binh. "Operating strategies to preserve the adequacy of power systems circuit breakers." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28232.
Повний текст джерелаАнотація:
Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.Committee Chair: Meliopoulos, A. P. Sakis; Committee Member: Divan, Deepakraj M.; Committee Member: Harley, Ronald G.; Committee Member: Johnson, Ellis L.; Committee Member: Taylor, David G.
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Langham, Ryan C. "Feasibility study and system architecture of radioisotope thermoelectric generation power systems for usmc forward operating bases." Monterey California. Naval Postgraduate School, 2013. http://hdl.handle.net/10945/34695.
Повний текст джерелаАнотація:
Approved for public release; distribution is unlimitedThis study sought to identify the feasibility of utilizing a radioisotope thermal (thermoelectric/stirling) generator to provide power to a deployed USMC Expeditionary Force. The conceptual system architecture was constructed through use of the systems engineering process, identifying necessary subsystems and integration boundaries. Radioisotope comparison was then performed, utilizing weighted design factors. It was determined that Sr-90, Cs-137, and Cm-244 would be the most effective fuel sources for this mission area. By analyzing current thermoelectric technology, it was determined that maximum system efficiency is limited to 1015 percent when utilizing available lead telluride thermoelectrics. Barriers to development of identified physical subsystem components were then identified, including health and environmental hazards of potential isotopes, as well as shielding criteria. The system development was found to be feasible and additional design work and development work is proposed.
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Ramos, Chavez Jose Ioav. "Design of high frequency operating mechatronic systems : tools and methods of characterization of electromagnetic couplings between electromechanic converters and power electronics converters." Thesis, Toulouse, INPT, 2016. http://www.theses.fr/2016INPT0075/document.
Повний текст джерелаАнотація:
De l’avion plus électrique, en passant par l’hybridation de véhicules automobiles et jusqu’aux implants cardiaques d’assistance circulatoire, la compacité est devenue le graal de l’électrotechnique embarquée moderne. En effet, la densité de puissance des systèmes électromécaniques ne cesse de s’accroitre. Ainsi, pour répondre aux besoins de forte intégration, les convertisseurs en électronique de puissance trouvent un vecteur de développement dans l’augmentation de leur température et des fréquences de fonctionnement mais aussi dans la réduction des temps de commutation des interrupteurs, leur permettant de réduire leurs pertes thermiques et ainsi, de réduire leurs besoins en refroidissement. Les moteurs et générateurs électriques évoluent avec des topologies aussi diverses qu’innovantes pour répondre aux besoins d’intégration, robustesse et sureté de fonctionnement. Particulièrement, les bobinages des moteurs sont les premiers éléments sur le front de bataille. Au sein du bobinage s’effectuent les échanges entre moteur et convertisseur. L’augmentation des contraintes fréquentielles et transitoires sous forme de fronts de courant et tension issus des ensembles d’électronique de puissance constituent des défis en termes de compatibilité électromagnétique (CEM) pour les systèmes embarqués. Le travail présenté ici est le fruit d’une étroite collaboration entre la société NOVATEM et le laboratoire Génie de Production de l’ENIT de Tarbes au travers d’un financement CIFRE, en association avec la plateforme Labceem de l’IUT de Tarbes. Il propose d’apporter des modèles prédictifs permettant de déterminer les conséquences de ces contraintes d’intégration dans les systèmes mécatroniques de puissance dès les premières étapes de leur conception. Les perturbations conduites dont la source HF est au sein des interrupteurs de puissance du convertisseur, sont façonnées par les impédances caractérisant le chemin de couplage dont le moteur fait partie intégrante. Ce travail vise à élaborer des méthodes et outils pour contribuer à l’étude prédictive de la compatibilité électromagnétique (CEM) des ensembles mécatroniques en essayant de couvrir une plage de fréquence allant de 0 à 300 MHz. Dans une première partie, un état de l’art est détaillé afin de délimiter le contexte et les frontières de l’étude. Puis, un deuxième chapitre porte sur la modélisation analytique de bobinages concentrés de moteurs électriques. Les modèles analytiques établis permettent de déterminer les paramètres de réseaux de circuits pour effectuer des simulations dans le domaine temporel et harmonique. Contrairement aux modèles comportementaux de moteurs répandus dans la littérature, les modèles ici synthétisés prennent en compte les paramètres physiques des bobinages. Ils donnent la possibilité à l’utilisateur de paramétrer les architectures de bobinages concentrés en changeant des paramètres tels que la géométrie des bobines, les matériaux d’isolation ou encore la perméabilité des culasses. Un troisième chapitre, détaille l’établissement d’une méthode rationnelle d’extraction numérique de paramètres fonctionnels et parasites des PCB multicouches de puissance. Cette méthode, de par la prise en compte de paramètres physiques, s’inscrit dans une logique générique et prédictive. Finalement, dans le dernier chapitre, les outils et méthodes précédemment établis sont appliqués à l’étude d’un système réel de motorisation de véhicule électrique développé par la société partenaire Novatem. Le caractère physique et prédictif de ces outils vise à permettre l’expérimentation virtuelle sur l’ensemble moteur-convertisseur sans la nécessité de prototypes. Ce dernier chapitre illustre l’intérêt d’une approche physique en modélisation pour la compatibilité électromagnétique de systèmes mécatroniquesFrom the more electrically operated aircraft, to the hybridization of motor vehicles, all the way to electromechanic cardiac implants, compactness has become the holy grail of modern embedded electrical engineering. Indeed, the power-to-weight ratio demands for electromechanical systems has greatly increased. To meet these high integration needs, power electronic converters find a vector of development by increasing their temperature and operating frequencies but also by reducing the switching time of power switches, thus enabling them to reduce their power losses and thereby reducing their cooling requirements. Electric motors and generators operate with various innovative topologies that meet integration, robustness and reliability needs. Motor windings, particularly, are the first motor components on the battle front. It is at the heart of the winding that occur the exchanges between motor and converter. In terms of electromagnetic compatibility (EMC) for embedded systems, the increased frequency and transient stresses in the form of current and voltage edges from the power electronic assemblies are considered steep challenges. The work presented herein is the result of a close cooperation between the company Novatem and the laboratory Génie de Production of ENIT de Tarbes, through CIFRE funding, in combination with the Labceem platform of IUT of Tarbes. Its aim is to develop predictive models that will serve to determine the consequences of such integration constraints in power mechatronic systems that are in the early stages of design. Conducted disturbances whose HF source is located at the inverter power switches are shaped by the impedances characterizing the coupling path of which the electrical machine is an integral part. This work proposes to develop methods and tools to support the predictive study of electromagnetic compatibility (EMC) of mechatronic assemblies, by attempting to cover a modeling frequency range that goes from 0 to 300 MHz’s. In the first chapter of this work, a literature review is detailed for the definition of the context and boundaries of the study. A second chapter focuses on the analytical modeling of concentrated windings in electric motors. The analytical models that are established allow determination of circuit networks settings to perform time- and frequency- domain simulations. Unlike the widespread behavioral models of electrical machine in the literature, the models that are synthesized here take into account the physical parameters of the coils. The user of such models is offered the opportunity to account for the different winding architectures, by changing core parameters such as geometry, insulation materials or permeability. A third chapter describes the establishment of a rational method for extraction of functional and parasitic parameters in multilayer Power PCBs. This method being of a generic and predictive logic aims to account for physical parameters. Finally, in the last chapter, the previously established tools and methods are applied to the study of a real electric vehicle drive system developed by the company Novatem. The physical and predictive value of these tools allows for execution of virtual experimentations on the motorconverter assembly without the need for prototypes. This chapter illustrates the value of a physical approach to modeling the electromagnetic compatibility of mechatronic systems
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Baradar, Mohamadreza. "On the Efficiency and Accuracy of Simulation Methods for Optimal Power System Operation : Convex Optimization Models for Power System Analysis, Optimal Utilization of VSC-type DC Wind Farm Grids and FACTS Devices." Doctoral thesis, KTH, Elektriska energisystem, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-166383.
Повний текст джерелаАнотація:
Recently, significant changes in electric power systems such as rapid developmentof smart grid and electricity market and integration of non-dispatchablesources have added more complexity to the Power Flow Scheduling (PFS) andPower Balancing (PB) models. For instance, non-dispatchable sources introducean increasing level of uncertainty in the electricity market and power system operation.One of the solutions for handling these uncertainties in the power systemoperation is the improvement of system flexibility through a more efficient operationof power systems. On the other hand, efficient operation can be achieved bywell capturing variable behavior of uncertain sources such as wind power sourceswhich in turn demands efficient and robust PFS/PB models. This way, a moreflexible system, capable of efficiently accommodating higher levels of wind powerchanges, can be achieved. All these factors increase a need for PFS/PB models suchas Power Flow (PF) and Optimal Power Flow (OPF) models which can addressthese new challenges in an efficient, reliable, and economic way while supportingthe power system operation and control. In this regard, various solution methodshave been developed for solving different forms of PF/OPF formulation. The difficultyof solving OPF problems increases significantly with increasing network sizeand complexity. One of these complexities is how to model advanced controllable devices such as HVDC grids and Flexible AC Transmission Systems (FACTS) devices.Accurate handling of these complexities has limited the use of OPF in manyreal-world applications mainly because of its associated computational challenges.The main reasons behind computational challenges are nonlinearity and especiallynon-convexity of constraints representing power system and its components. Inthis regard, OPF problems are classified into two main groups. In the first group,researchers adopt Nonlinear programming (NLP) approach to fully represent thenonlinearity of the power system for the sake of accuracy but with the cost of complexityin the model. Computational and theoretical challenges associated withNLP approaches are then used as a motivation towards developing a more simplifiedOPF model, leading to the second group of OPF models known as LinearProgramming (LP) based OPF models. LP approaches are fast, reliable, and especiallyconvex, and therefore guarantee a global optimum to the simplified OPFproblem. The problem of LP approach to OPF is that the LP solution of OPF may not even be a feasible solution of original nonlinear OPF at all. Another issueassociated with LP models is that complex power system devices such as HVDClinks are difficult to be incorporated. These limitations have restricted the applicationof LP approaches for many OPF problems. According to the mentionedadvantages and disadvantages of NLP and LP based OPF models, what we seeks isan OPF model which can have main advantages of both LP OPF models (Efficientnumerical solvers) and full AC OPF models (Results accuracy). In this thesis, wedevelop convex optimization problems which can be adopted as both PF and OPFmodels which are capable of catching the nonlinear nature of power systems asmuch as possible while can be solved by efficient solution methods such as InteriorPoint Methods (IPMs). These OPF models can incorporate HVDC links, windfarm Multi Terminal HVDC (MTDC) grids, and shunt FACTS devices.QC 20150521
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Yagci, Mahmut Emre. "Development Of A Picosecond Pulsed Mode-locked Fiber Laser." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615773/index.pdf.
Повний текст джерелаАнотація:
Fiber lasers represent the state-of-the-art in laser technology and hold great promise for a
wide range of applications because they have a minimum of exposed optical interfaces,
very high efficiency, and are capable of exceptional beam quality. In the near future, the
most important markets such as micromachining, automotive, biomedical and military
applications will begin to use this technology. The scope of this thesis is to design and
develop a short picosecond pulsed fiber laser using rare-earth doped fiber as a gain
medium. The proposed master oscillator power amplifier (MOPA) will be used to generate
pulses with high repetition rates.
In this study, first we explain the basic theoretical background of nonlinear optics and fiber
laser. Then, the numerical simulation will be introduced to explain how the laser system
design and optimization. The simulation is based on nonlinear Schrödinger equation with the method of split-step evaluation. The brief theoretical background and simulation results of the laser system will be shown. Finally, the experimental study of the developmental fiber laser system that comprises an oscillator, preamplifier and power amplifier will be discussed.
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Soderquist, Daniel Robert. "Analysis of Distortion Transfer and Generation through a Fan and a Compressor Using Full-annulus Unsteady RANS and Harmonic Balance Approaches." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7401.
Повний текст джерелаАнотація:
Understanding distortion transfer and generation through fan and compressor blade rows is able to assist in blade design and performance prediction. Using full annulus unsteady RANS simulations, the effects of distortion as it passes through the rotor of a transonic fan at five radial locations (10%, 30%, 50%, 70%, and 90% span) are analyzed. The inlet distortion profile is a 90-degree sector with a 15% total pressure deficit. Fourier distortion descriptors are used in this study to quantitatively describe distortion transfer and generation. Results are presented and compared for three operating points (near-stall, design, and choke). These results are used to explain the relationship between inlet total pressure distortion, pressure-induced swirl, total pressure distortion transfer, total temperature distortion generation, and circumferential rotor work variation. It is shown that very large changes in pressure-induced swirl and distortion transfer and generation occur between near-stall and design, but only small changes are seen between design and choke. The greatest changes are shown to be near the tip. Local power variations are shown to correlate with total pressure distortion transfer and total temperature distortion generation.It can be difficult to predict the transfer of distortion through a fan or compressor because traditional experimental and computational methods are very expensive and time consuming. The Harmonic Balance approach is a promising alternative which uses Fourier techniques to represent fluid flow solutions and which can provide unsteady solutions much more quickly than traditional unsteady solvers. Relatively little work has been done to assess how much Fourier information is necessary to calculate a sufficiently accurate solution with the Harmonic Balance Solver. A study is performed to analyze the effects of varying the amount of modal content that is used in Harmonic Balance simulations. Inlet distortion profiles with varying magnitudes are used in order to analyze trends and provide insight into the distortion flow physics for various inlet conditions. The geometry is a single stage axial compressor that consists of an inlet guide vane followed by the NASA Stage 37 rotor. It is shown that simulations with greater magnitudes of distortion require more modal content in order to achieve sufficiently accurate results. Harmonic Balance simulations are shown to have significantly lower computational costs than simulations with a conventional unsteady solver.
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McMorran, Alan Walter. "Using the Common Information Model for power systems as a framework for applications to support network data interchange for operations and planning." Thesis, University of Strathclyde, 2006. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21648.
Повний текст джерелаАнотація:
The Common Information Model (CIM) is an object-oriented representation of a power system used primarily as a data exchange format for power system operational control systems and as a common semantic model to facilitate enterprise application integration. The CIM has the potential to be used as much more than an intermediary exchange language and this thesis explores the use of the CIM as the core of a power systems toolkit for storing, processing, extracting and exchanging data directly as CIM objects. This thesis looks at the evolving nature of the CIM standard and proposes a number of extensions to support the use of the CIM in the UK power industry while maintaining, where possible, backwards compatibility with the IEC standard. The challenges in storing and processing large power system network models as native objects without sacrificing reliability and robustness are discussed and solutions proposed. A number of applications of this CIM software framework are described in this thesis aimed at facilitating the use of the CIM for exchanging data for network planning and operations. The development of novel algorithms is described that use the underlying CIM class structure to convert power system network data in a CIM format to the native, proprietary format of an external analysis application. The problem of validating CIM data against pre-defined profiles and the deficiencies of existing validation techniques is discussed. A novel validation system based on the CIM software framework is proposed that provides a means of performing a level of validation beyond any existing tools. Algorithms to allow the integration of independent power system network models in a CIM format are proposed that allow the automatic identification and removal of overlapping areas and integration of neighbouring networks. The development of an application to dynamically generate network diagrams of power system network models in CIM format via the novel application of existing, generic data visualisation tools is described. The use of web application technologies to create a remotely-accessible tool for creating power system network models in CIM format is described. Each of these applications supports a stage of the planning process allowing both planning and operational engineers to create, exchange and use data in the CIM format by providing tools with a native CIM architecture that can adapt to the evolving CIM standard.
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Петренко, А. М. "Система електропостачання тепличного комплексу «АсканіяФлора»". Thesis, Чернігів, 2021. http://ir.stu.cn.ua/123456789/25280.
Повний текст джерелаАнотація:
Петренко, А. М. Система електропостачання тепличного комплексу «АсканіяФлора» : випускна кваліфікаційна робота : 141 "Електроенеретика, електротехніка та електромеханіка" / А. М. Петренко ; керівник роботи А. В. Красножон ; НУ "Чернігівська політехніка", кафедра електричної інженерії та інформаційно-вимірювальних технологій. – Чернігів, 2021. – 15 с.Об'єкт дослідження – система внутрішнього електропостачання тепличного комплексу «Асканія-Флора». Мета роботи – спроектувати систему внутрішнього електропостачання нового тепличного комплексу. У магістерському проекті проведено оцінювання режиму роботи діючої системи електропостачання 10 кВ, в результаті чого отримано, що втрати в лініях незначні, а трансформатори працюють без перевантаження. Спочатку була спроба адаптувати діючу систему внутрішнього електропостачання «Асканія-Флора» до збільшення навантаження за рахунок дозавантаження існуючих трансформаторних підстанцій 10/0,4 кВ до номінальних потужностей та компенсації їх навантаження по реактивній потужності по стороні низької напруги. Але дана спроба не дала бажаного результату, тому було розроблено проект електропостачання з новими трансформаторними підстанціями та мережами живлення 10 кВ від розподільчого пункту підстанції «Асканія». Вибране електрообладнання перевірено в аварійному режимі. В проекті було прийнято рішення компенсувати реактивну потужність по стороні 10 кВ. Проведено техніко-економічне обґрунтування запропонованого варіанту системи електропостачання. Спроектовано заземлюючі пристрої для нових трансформаторних підстанцій.
The object of study - the internal power supply system of the greenhouse complex "Askania-Flora". The purpose of the work is to design the internal power supply system of the new greenhouse complex. In the master's project, the operation of the existing 10 kV power supply system was evaluated, as a result of which it was found that the losses in the lines are insignificant, and the transformers operate without overload. Initially, there was an attempt to adapt the existing internal power supply system "Askania-Flora" to increase the load by reloading the existing 10 / 0.4 kV transformer substations to rated capacities and compensating for their load on the reactive power on the low voltage side. But this attempt did not give the desired result, so a power supply project was made with new transformer substations and 10 kV power supply networks from the distribution point of the Askania substation. The selected electrical equipment is tested in emergency mode. The project decided to compensate the reactive power on the 10 kV side. Feasibility study of the proposed variant of the power supply system is carried out. Earthing devices for new transformer substations are designed.
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Doban, Nicolae. "Building predictive models for dynamic line rating using data science techniques." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-187812.
Повний текст джерелаАнотація:
The traditional power systems are statically rated and sometimes renewable energy sources (RES) are curtailed in order not to exceed this static rating. The RES are curtailed because of their intermittent character and therefore, it is difficult to predict their output at specific time periods throughout the day. Dynamic Line Rating (DLR) technology can overcome this constraint by leveraging the available weather data and technical parameters of the transmission line. The main goal of the thesis is to present prediction models of Dynamic Line Rating (DLR) capacity on two days ahead and on one day ahead. The models are evaluated based on their error rate profiles. DLR provides the capability to up-rate the line(s) according to the environmental conditions and has always a much higher profile than the static rating. By implementing DLR a power utility can increase the efficiency of the power system, decrease RES curtailment and optimize their integration within the grid. DLR is mainly dependent on the weather parameters and specifically, in large wind speeds and low ambient temperature, the DLR can register the highest profile. Additionally, this is especially profitable for the wind energy producers that can both, produce more (until pitch control) and transmit more in high wind speeds periods with the same given line(s), thus increasing the energy efficiency. The DLR was calculated by employing modern Data Science and Machine Learning tools and techniques and leveraged historical weather and transmission line data provided by SMHI and Vattenfall respectively. An initial phase of Exploratory Data Analysis (EDA) was developed to understand data patterns and relationships between different variables, as well as to determine the most predictive variables for DLR. All the predictive models and data processing routines were built in open source R and are available on GitHub. There were three types of models built: for historical data, for one day-ahead and for two days-ahead time-horizons. The models built for both time-horizons registered a low error rate profile of 9% (for day-ahead) and 11% (for two days-ahead). As expected, the predictive models built on historical data were more accurate with an error as low as 2%-3%. In conclusion, the implemented models met the requirements set by Vattenfall of maximum error of 20% and they can be applied in the control room for that specific line. Moreover, predictive models can also be built for other lines if the required data is available. Therefore, this Master Thesis project’s findings and outcomes can be reproduced in other power lines and geographic locations in order to achieve a more efficient power system and an increased share of RES in the energy mix
44
Makdessi, Maawad. "Modélisation, vieillissement et surveillance de l'état de santé des condensateurs films utilisés dans des applications avioniques." Phd thesis, Université Claude Bernard - Lyon I, 2014. http://tel.archives-ouvertes.fr/tel-01058227.
Повний текст джерелаАнотація:
Le domaine aéronautique connait de nos jours un engouement sans précédent autour de l'avion plus électrique. L'importance du nombre d'équipements électriques est à un tel point que l'amélioration de leur fiabilité devient incontournable. Actuellement, les composants passifs occupent 75 % des éléments électroniques utilisés en avionique dont la moitié correspond à des condensateurs. Ces derniers doivent donc répondre aux exigences environnementales avioniques assez contraignantes. C'est dans ce contexte que nous nous sommes intéressés particulièrement à l'étude des condensateurs à technologie film utilisant le polypropylène ou le polyester comme diélectrique. Afin de mieux comprendre le comportement fréquentiel de cette technologie, deux modèles fins de condensateurs films ont été développés, permettant ainsi de suivre les évolutions de leurs grandeurs électriques dans des conditions cohérentes avec l'application. Dans un deuxième temps, l'effet des contraintes en tension et en température constantes a été étudié sous la forme de facteurs d'accélération du vieillissement. Cela a été établi par l'intermédiaire de plusieurs essais, permettant d'établir les lois d'évolutions temporelles des paramètres électriques des condensateurs. Comme ces contraintes constantes ne sont pas toujours représentatives des conditions réelles d'utilisation, les cinétiques de dégradation ont été comparées à celles où les condensateurs sont sollicités par de fortes ondulations de courant, seules ou associées à une tension continue. Enfin, la dernière partie de notre travail expose l'utilisation des données expérimentales issues des essais de vieillissement dans un objectif de diagnostic en ligne. Les techniques utilisées assurent l'analyse de la dégradation de ces composants, étape essentielle dans la prédiction de l'état de santé des condensateurs en ligne
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Kowshik, Raghu V. "A structural equation model of the factors associated with influence and power of IT departments and their relationship to firm's IT orientation and business performance." ScholarWorks, 2010. https://scholarworks.waldenu.edu/dissertations/827.
Повний текст джерелаАнотація:
Although few firms can function without an information technology (IT) department, senior executives often consider IT as secondary. Historically, studies have found IT departments to have low influence and power status compared to other departments. Few, if any, studies have investigated what factors contribute to this subservient position. Three research questions that inspired this study regarding the IT department's influence and power included factors that shape the IT influence and power, the consequences for the firm's IT orientation and business performance, and how firm's IT orientation affects business performance. This quantitative study explored the notion that accountability, innovativeness, customer connectedness and partnering with other departments positively affect the IT department's influence and power. A synthesis of resource dependence and strategic contingency theories framed the theoretical basis for the structural equation model analyzed in this study. Responses from a Web panel of 349 anonymous, voluntary senior managers of firms operating in various industry types provided the data. Analysis results showed that accountability, innovativeness, and partnering with other departments positively affect the IT department's influence and power. Also, the firm's IT orientation, more so than IT department's influence and power, positively affects business performance. Results help IT executives to become more influential and enhance their ability to participate in their firm's strategic decisions. From social change perspective, influential IT managers can affect strategic decisions regarding social programs, implement new IT tools to do more with less, and new ways of distributing critical information and resources to enhance the speed of response when and where needed.
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Prokop, Ondřej. "Analýza provozu uzlu sítě po připojení jaderného bloku velkého výkonu." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-242013.
Повний текст джерелаАнотація:
The thesis deals with the analysis of the grid node operation after the connection the nuclear unit. The aim of the master´s thesis is to describe the influence of network´s faults to a nuclear unit. Thesis is dealing with three fundamental problems. An influence of short circuits and power imbalance on the synchronous generator of nuclear power plant and its operation of the island network. The thesis is focused especially on the nuclear unit. However, in the case of any failure in the network, it´s necessary to check other units and their protections in the test system because unit failure could cause the disintegration of the power network. For the purposes of the simulation a test system of the power network has been developed. The test system was optimized in the LUG software, which is used to calculate the power network. Transient simulations are performed in the MODES software. Single faults are configured with scenarios. Results are generated into output files. Analysis of influence network´s faults on the synchronous generator of nuclear power plants. The ability of the synchronous generator to restore the primary steady state or hold the new steady state during changes in operating parameters of the network is one of the important parts of the safe and reliable operation of the power network. During the short circuit the damped transient actions occur. With the extension of the short circuit duration, the amplitude of the transient action increases. The risk of the stability loss of a synchronous generator increases. Therefore, the critical clearing time of a short circuit is being defined, which is the time when there is not any loss of stability. Critical clearing time of research generator is sufficient to turn off the short circuit with the help of its protection (the worst case is 0,8 s). For example, by comparison with the hydroelectric power plant, the critical clearing time is much longer. Models of other power plants have been designed with high reliability so in the case of these faults, it doesn’t cause the disintegration of the power network. Creation of island grid is characterized by strong current surges. Units must be resistant to these surges. In the island grid fast changes of the electrical parameters often occurs. Therefore, units must respond to these changes as quickly as possible and in the broadest limits. For this purpose an island operation regulator is being used. In the case of surplus island grid in steam power plants a dump condenser can be used. This is an important ability of steam power plants because the units are able to react quickly to changes of electrical parameters in island grid. The main result of this thesis is the behavior of the nuclear power plant during various faults in the power network. Researched generator of the nuclear power plant is highly stable against faults in the power network based on the findings. The results allow to continue in this topic with real network and real unit of nuclear power plant.
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Bank, Jason Noah. "Propagation of Electromechanical Disturbances across Large Interconnected Power Systems and Extraction of Associated Modal Content from Measurement Data." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/73008.
Повний текст джерелаАнотація:
Changes in power system operating conditions cause dynamic changes in angle and frequency. These disturbances propagate throughout the system area with finite speed. This propagation takes the form of a traveling wave whose arrival time at a particular point in the system can be observed using a wide-area measurement system (WAMS). Observations of these waves both through simulation and measurement data have demonstrated several factors that influence the speed at which a disturbance propagates through a system. Results of this testing are presented which demonstrate dependence on generator inertia, damping and line impedance. Considering a power system as an area with and uneven distribution of these parameters it is observed that a disturbance will propagate throughout a system at different rates in differing directions. This knowledge has applications in locating the originating point of a system disturbance, understanding the overall dynamic response of a power system, and determining the dependencies between various parts of that system.
A simplified power system simulator is developed using the swing equation and system power flow equations. This simplified modeling technique captures the phenomenon of traveling electromechanical waves and demonstrates the same dependencies as data derived from measurements and commercial power system simulation packages. The ultimate goal of this research is develop a methodology to approximate a real system with this simplified wave propagation model. In this architecture each measurement point would represent a pseudo-bus in the model. This procedure effectively lumps areas of the system into one equivalent bus with appropriately sized generators and loads. With the architecture of this reduced network determined its parameters maybe estimated so as to provide a best fit to the measurement data. Doing this effectively derives a data-driven equivalent system model. With an appropriate equivalent model for a given system determined, incoming measurement data can be processed in real time to provide an indication of the system operating point. Additionally as the system state is read in through measurement data future measurements values along the same trajectory can be estimated. These estimates of future system values can provide information for advanced control and protection schemes.
Finally a procedure for the identification and extraction of inter-area oscillations is developed. The dominant oscillatory frequency is identified from an event region then fit across the surrounding dataset. For each segment of this data set values of amplitude, phase and damping are derived for each measurement vector. Doing this builds up a picture of how the oscillation evolves over time and responds to system conditions. These results are presented in a graphical format as a movie tracking the modal phasors over time. Examples derived from real world measurement data are presented.Ph. D.
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Al-Hadban, Yehya. "Demand-side management in office buildings in Kuwait through an ice-storage assisted HVAC system with model predictive control." Thesis, Cranfield University, 2005. http://hdl.handle.net/1826/3885.
Повний текст джерелаАнотація:
Examining methods for controlling the electricity demand in Kuwait was the main
objective and motivation of this researchp roject. The extensiveu se of air-conditioning
for indoor cooling in office and large commercial buildings in Kuwait and the Gulf
States represents a major part of the power and electricity consumption in such
countries. The rising electricity generation cost and growing rates of consumption
continuously demand the construction new power plants. Devising and enforcing
Demand-SideM anagemen(t DSM) in the form of energye fficient operations trategies
was the response of this research project to provide a means to rectify this situation
using the demand-side management technique known as demand levelling or load
shifting. State of the art demand-sidem anagementte chniquesh ave been examined
through the developmenot f a model basedp redictive control optimisations trategyf or
an integrateda ndm odulara pproachto the provisiono f ice thermals torage.
To evaluate the potential of ice-storage assisted air-conditioning systems in flattening
the demand curve at peak times during the summer months in Kuwait, a model of a
Heating, Ventilation, and Air-conditioning (HVAC) plant was developed in Matlab. The
model engaged the use of model based predictive control (MPQ as an optimisation tool
for the plant as a whole. The model with MPC was developed to chose and decide on
which control strategy to operate the integrated ice-storage HVAC plant. The model
succeeded in optimising the operation of the plant and introduced encouraging
improvement of the performance of the system as a whole.
The concept of the modular ice-storage system was introduced through a control zoning
strategy based on zonal orientation. It is believed that such strategy could lead to the
modularisation of ice-storage systems. Additionally, the model was examined and tested
in relation to load flattening and demonstrated promising enhancement in the shape of
the load curve and demonstrated flattened demand curves through the employed
strategy. When compared with measured data from existing buildings, the model
showed potential for the techniques utilised to improve the load factor for office
buildings.
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Modesto, Sonia Angelina Garcia. "Um modelo de despacho e pré-despacho de retaivas através de algoritmos genéticos, fluxo de potência ótimo e busca tabu = A model of reactive dispatch and a model of short-term reactive operation planning through geneti algorithms, optimal power flow and search tabu." [s.n.], 2003. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261159.
Повний текст джерелаАнотація:
Orientador: Takaaki OhishiTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
Made available in DSpace on 2018-08-21T16:39:20Z (GMT). No. of bitstreams: 1 Modesto_SoniaAngelinaGarcia_D.pdf: 7966542 bytes, checksum: e394ce8619b189ec96e83326835c45df (MD5) Previous issue date: 2003
Resumo: Esta tese trata do problema de planejamento da operação de curto prazo (operação diária) de reativos. A Cadeia de Planejamento do Setor Elétrico brasileiro inicia com um Planejamento de Longo Prazo, o qual considera a operação do sistema através de modelos equivalentes em um horizonte de cinco anos. Em seguida o Planejamento de Médio Prazo, utilizando um modelo individualizado para cada usina hidrelétrica e termelétrica, analisa a operação para um horizonte de um ano à frente. A próxima etapa é de Programação da Operação, a qual determina a operação do sistema para o horizonte de alguns dias à frente. Finalmente, a solução da Programação da Operação é utilizada pela operação em tempo real como uma referência operativa. Em todas estas etapas, as modelagens representam apenas a geração e transmissão de potência ativa (Modelo DC). Para a parte reativa não há planejamento. Neste estudo sobre a parte reativa, enfocou-se o aspecto das variáveis discretas, mais precisamente os taps dos transformadores. Supõe-se conhecido um despacho de geração ativa, dado pela Programação da Operação, e um despacho de potência reativa, obtido por exemplo através de um caso base, ou através de um modelo de fluxo de potência ótimo reativo. Inicialmente foi estudado o problema de despacho de reativos, o qual considera o operação em um dado instante de tempo (problema estático). Para este problema, foram desenvolvidos três abordagens. A primeira é uma metodologia híbrida combinando Algoritmos Genéticos (AG) e um modelo de Fluxo de Potência Ótimo (FPO). Nesta abordagem as variáveis discretas são tratadas através dos AG e cada indivíduo é avaliado através de um FPO. A vantagem desta metodologia é que esta determina conjuntamente as variáveis continuas (geração de potência ativa e reativa) e as variáveis discretas; a desvantagem é o elevado tempo computacional. Buscando diminuir o tempo de processamento, foram desenvolvidos duas outras metodologias, uma utilizando um método de Busca Local e a outra baseada em Busca Tabu. Em ambas as metodologias, o FPO foi substituído por um modelo de fluxo de potência não linear. O plano de operação reativa ao longo de um dia, aqui denominado prédespacho de reativos, visa estimar uma solução em termos do posicionamento dos taps para cada intervalo do dia, buscando obter um perfil de tensão mais adequado do ponto de vista operativo. A abordagem para o pré-despacho de reativos utiliza o modelo de despacho de reativos baseado em Busca Tabu, mas considera a solução obtida no intervalo anterior. Todas as metodologias utilizaram o sistema IEEE30 como sistema teste
Abstract: This thesis treats the short-term (daily operation) reactive operation planning. The Brazilian operation planning initially performs a long-term operation study. This planning uses a equivalent model representation and take into account a time horizon of five years. The next step is the mid operation planning, that uses a individual representation and considers one year operation. The last planning determines the short-term operation using a more detailed model, including transmission operation constraints through a linear model. Finally, this short-term planning is used as operational guidelines in the real time operation. The models used in these different planning represent only the active power generation and transmission. For reactive operation there are not planning. This study about reactive operation focused the discrete decision. More specifically, the taps are treated as discrete variables. The methodologies supposes that the active and reactive power generations are given. Initially, the reactive dispatch problem is treated, and three methodologies are developed. The first is a hybrid model, that combines a Genetic Algorithm approach with an Optimal Power Flow model. This methodology has the advantage to determine the active and reactive generations and discrete variables values; the inconvenient is the high computer time processing. Two others methodologies are developed in order to obtain more faster approach. One approach is based on Local Search and the other is based on Tabu Search. In both methodologies, the OPF model is substituted by a non-linear power flow. The proposed daily reactive operation planning aims to determines the taps position for each time interval, looking for a more operationally suitable voltage profile. This planning is based on the Tabu Search Reactive Dispatch model. All methodologies used the IEEE30 as test system
Doutorado
Automação
Doutora em Engenharia Elétrica
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Rojas, Ramirez Jorge. "Etude des modes de marche des systèmes automatisés de production pour la définition des stratégies de conduite." Valenciennes, 1995. https://ged.uphf.fr/nuxeo/site/esupversions/03812cc0-768c-417f-8fe3-9769898cd48e.
Повний текст джерелаАнотація:
Les systèmes automatisés de production, ayant acquis des performances importantes en fonctionnement normal, doivent aussi être réactifs face aux perturbations de la fabrication. Une analyse est réalisée sur ces systèmes pour la proposition de stratégies d'exploitation utilisant le potentiel des alternatives de configuration pour l'exécution de la fabrication. Pour apporter des solutions a ce problèmes, divers critères existent, allant de l'intervention humaine aux réponses automatisées. Prenant en compte l'organisation hiérarchique du système, la réaction est entreprise au niveau de la conduite pour le cas des défaillances des ressources. Les configurations alternatives possibles du système représentent des modes dégradés de fonctionnement, comportant des performances variées, qui doivent être évaluées pour la prise de décision. Un modèle des modes de marche est défini pour la conduite du système, comme outil d'assistance à sa réactivité. Les alternatives comprennent la reprise après réparation, le fonctionnement dégradé des ressources et le réordonnancement des opérations. La solution pour la reprise de la fabrication est suggérée à travers une démarche qui comprend les étapes de génération, d'évaluation, de vérification et de spécification des alternatives. La contribution de cette étude réside en la caractérisation des modes dégradés de fonctionnement, par une réaction rapide basée sur une évaluation des temps de fabrication. Une méthode de réaction est proposée, intégrant les stratégies de solution en fonction de l'urgence et du respect des contraintes de production. La décision prend en compte les consignes de la gestion de production, l'état réel des ressources et les données de la maintenance. La méthode comprend des stratégies à court terme, utilisant le mode dégradé ou la réparation de la ressource défaillante et des stratégies à moyen terme par reconfiguration du système, évaluées par le calcul des durées de fabrication. Une application sur des exemples permet l'évaluation de la méthode développée.