Dissertations / Theses on the topic 'Electrical energy transmission, networks and systems'
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Clegg, Stephen. "Integrated modelling of electrical and gas transmission networks in multi-energy systems." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/integrated-modelling-of-electrical-and-gas-transmission-networks-in-multienergy-systems(e1b07a2b-8bd2-472d-8274-8d54978e9770).html.
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The scope of this thesis is an investigation into the interactions between the gas and electrical transmission networks in the context of a low-carbon energy system with explicit considerations of the role played by multi-energy vectors, including heating, in future scenarios. Many energy systems are in a state of transition due to the growing need to reduce their carbon impact while maintaining reliability and reducing costs. The generation capacity of gas-fuelled power stations, as a cleaner alternative to coal, has been continuing to grow in many power systems. Furthermore, their operational characteristics are evolving as they are increasingly used to meet demand when there is a shortfall in renewable generation and are playing a role in contributing to the reliability of the power system. Additionally, changes to the heating sector (e.g., the electrification of heat or the increased use of combined heat-and-power) and the introduction of power-to-gas (to convert excess renewable electricity into hydrogen for successive energy generation) all lead to tighter interactions between the heat, gas and power sectors which require a multi-energy framework to assess. In this work this is achieved, firstly, through the development of integrated gas and power network modelling techniques. The power system modelling incorporates a multi-temporal DC optimal power flow, while gas network models use steady-state and transient flow analysis to allow for an assessment of the pressures and flows around the network. Additionally, a novel heat model is presented for a regional assessment of the heating demands of the British energy system, so that the impacts of changes to heating technologies on the gas and electrical transmission networks can be quantified in whole-energy system case studies. Power-to-gas technologies where (excess renewable) electrical energy is converted to hydrogen and then potentially synthetic natural gas which is then injected into the gas network where it can be stored and transported have the potential to increase the integration of renewable resources and reduce the carbon impact of both electricity and heating sectors. Models are presented which assess the operation of power-to-gas and its impact on the gas and electrical transmission networks as well as the benefits to the energy system. This uses power system modelling to assess the excess renewable energy (from wind and solar resources) that can be used in the power-to-gas process, with the amounts of produced hydrogen and synthetic natural gas also being evaluated considering constraints imposed by the gas network. The resulting case studies evaluate the impact on the gas and electrical networks and the benefit to the energy system by displacing natural gas and reducing carbon emissions. To assess the extent to which gas power stations can change their output to follow changes in renewable generation output, an integrated gas and electrical network flexibility model has been developed. This uses the notion of zonal linepack flexibility and allows for limits to be applied to the ability of gas turbines to change their output over the forthcoming hours with consideration of the intermittent nature of renewable generation. The developed models and methodologies are incorporated into a number of case studies using the British gas and electrical networks and heating sector showing their applicability to assessing future energy system needs.
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Qiao, Wei. "Integrated control of wind farms, facts devices and the power network using neural networks and adaptive critic designs." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/29716.
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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.Committee Chair: Ronald G. Harley; Committee Member: David G. Taylor; Committee Member: Deepakraj M. Divan; Committee Member: Ganesh Kumar Venayagamoorthy; Committee Member: Thomas G. Habetler. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Lazaro, Orlando. "CMOS inductively coupled power receiver for wireless microsensors." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51874.
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This research investigates how to draw energy from a distant emanating and alternating (i.e., AC) magnetic source and deliver it to a battery (i.e., DC). The objective is to develop, design, simulate, build, test, and evaluate a CMOS charger integrated circuit (IC) that wirelessly charges the battery of a microsystem. A fundamental challenge here is that a tiny receiver coil only produces mV's of AC voltage, which is difficult to convert into DC form. Although LC-boosted diode-bridge rectifiers in the literature today extract energy from similar AC sources, they can do so only when AC voltages are higher than what miniaturized coils can produce, unless tuned off-chip capacitors are available, which counters the aim of integration. Therefore, rather than rectify the AC voltage, this research proposes to rectify the current that the AC voltage induces in the coil. This way, the system can still draw power from voltages that fall below the inherent threshold limit of diode-bridge rectifiers. Still, output power is low because, with these low currents, small coils can only extract a diminutive fraction of the magnetic energy available, which is why investing battery energy is also part of this research. Ultimately, the significance of increasing the power that miniaturized platforms can output is higher integration and functionality of micro-devices, like wireless microsensors and biomedical implants.
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Yow, Thiam Poh. "Tunneled data transmission over wireless sensor networks." Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion-image.exe/07Dec%5FYow.pdf.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, December 2007.Thesis Advisor(s): McEachen, John C. ; Tummala, Murali. "December 2007." Description based on title screen as viewed on January 24, 2008. Includes bibliographical references (p. 73-74). Also available in print.
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Condò, Marco. "Electrical characterization of innovative insulating materials for HVDC energy transmission cable systems." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
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La tesi si è svolta nel corso di uno stage di quasi nove mesi all'interno del laboratorio elettrico di alta tensione del reparto R&D di Prysmian, leader mondiale dei sistemi elettrici in cavo. La tesi si è articolata nelle fasi seguenti:
1) analisi dei fondamenti teorici dei sistemi elettrici in cavo ad alta tensione in corrente continua (HVDC);
2) caratterizzazione elettrica di materiali isolanti innovativi per lo sviluppo di sistemi in cavo HVDC. Più in dettaglio tale caratterizzazione è consistita nelle fasi seguenti:
a) progettazione e/o realizzazione dei set-up di prova;
b) esecuzione delle prove di conducibilità elettrica su provini piani di materiale isolante costituiti da diverse mescole candidate per la realizzazione di cavi modello nella seconda parte della caratterizzazione (vedi seguito);
c) elaborazione dei dati delle prove di cui al punto b) per ricavare i parametri σ0, α e β della conducibilità di ogni mescola isolante testata - e quindi l’andamento della conducibilità delle mescole in funzione della temperatura e del gradiente elettrico – così da selezionare le mescole migliori per la realizzazione dei cavi modello (cavi in scala ridotta con dimensioni standardizzate realizzati ai fini di prove di sviluppo);
d) esecuzione delle prove di tenuta in AC sui cavi modello selezionati;
e) esecuzione delle prove di rigidità ad impulso atmosferico su cavi modello;
f) esecuzione delle prove di stabilità termica su cavi modello.
I risultati di tutte le prove condotte hanno consentito di determinare quali fossero, tra tutte le mescole prese in esame, le più performanti dal punto di vista elettrico.
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Chen, Chao. "Energy-efficient electrical and silicon-photonic networks in many core systems." Thesis, Boston University, 2014. https://hdl.handle.net/2144/10962.
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Thesis (Ph.D.)--Boston UniversityDuring the past decade, the very large scale integration (VLSI) community has migrated towards incorporating multiple cores on a single chip to sustain the historic performance improvement in computing systems. As the core count continuously increases, the performance of network-on-chip (NoC), which is responsible for the communication between cores, caches and memory controllers, is increasingly becoming critical for sustaining the performance improvement. In this dissertation, we propose several methods to improve the energy efficiency of both electrical and silicon-photonic NoCs. Firstly, for electrical NoC, we propose a flow control technique, Express Virtual Channel with Taps (EVC-T), to transmit both broadcast and data packets efficiently in a mesh network. A low-latency notification tree network is included to maintain t he order of broadcast packets. The EVC-T technique improves the NoC latency by 24% and the system energy efficiency in terms of energy-delay product (EDP) by 13%. In the near future, the silicon-photonic links are projected to replace the electrical links for global on-chip communication due to their lower data-dependent power and higher bandwidth density, but the high laser power can more than offset these advantages. Therefore, we propose a silicon-photonic multi-bus NoC architecture and a methodology that can reduce the laser power by 49% on average through bandwidth reconfiguration at runtime based on the variations in bandwidth requirements of applications. We also propose a technique to reduce the laser power by dynamically activating/deactivating the 12 cache banks and switching ON/ OFF the corresponding silicon-photonic links in a crossbar NoC. This cache-reconfiguration based technique can save laser power by 23.8% and improves system EDP by 5.52% on average. In addition, we propose a methodology for placing and sharing on-chip laser sources by jointly considering the bandwidth requirements, thermal constraints and physical layout constraints. Our proposed methodology for placing and sharing of on-chip laser sources reduces laser power. In addition to reducing the laser power to improve the energy efficiency of silicon-photonic NoCs, we propose to leverage the large bandwidth provided by silicon-photonic NoC to share computing resources. The global sharing of floating-point units can save system area by 13.75% and system power by 10%.
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Khan, Nabeel Pervaiz. "Energy efficient communication and rate control algorithms for wireless sensor networks." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 114 p, 2009. http://proquest.umi.com/pqdweb?did=1818417511&sid=4&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Lopes, Luiz Antonio Correa. "On the utilization of force-commutated AC controllers in AC power transmission systems." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40387.
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Recent economic pressures to enhance the transmission capability and controllability of existing power systems have led the new concept of Flexible AC Transmission System (FACTS). The use of power electronics in fast acting power controllers is one of the backbones of the implementation of FACTS.This thesis deals with the use of force-commutated Pulse Width Modulated (PWM) ac controller technology in phase-shifting and var compensation applications. The proposed technology employes as the building block a 4-switch PWM ac controller, which is controlled by means of duty cycle variation. The difficulties of using PWM in high power applications are overcome with a new multi-module PWM ac controller operated with symmetrically phase shifted carriers. This solution results in harmonic cancellation and consequently in high quality (less distortion) waveforms with the power switches (GTO) switching at low frequencies, thus keeping the communication losses low. The resulting power controllers can be considered as intermediate FACTS devices in terms of performance and flexibility.
An application of one phase-shifter and two var compensators in a tie line is also proposed for suppressing inter-area power oscillations. In this scheme the inter-area mode is deactivated if the FACTS devices keep constant the active and reactive power that flow in the tie line. Furthermore, the two interconnected subsystems were virtually decoupled with the proposed approach, in the sense that the small signal disturbances that occur in one side of the tie line do not affect the machines of the other side.
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Farhat, Jamil de Araujo. "Eficiência energética e throughput seguros em decode-and-forward seletivo com alocação de potência distribuída." Universidade Tecnológica Federal do Paraná, 2015. http://repositorio.utfpr.edu.br/jspui/handle/1/1368.
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Investiga-se a eficiência energética e o throughput seguros em sistemas de comunicações sem fio cooperativos, em que um par de usuários legítimos (Alice e Bob) são auxiliados por um nó relay e em que a comunicação ocorre na presença de um espião passivo (Eve). Diversos protocolos cooperativos são comparados em relação a estas medidas e se utiliza um algoritmo iterativo e distribuído, baseado no algoritmo Dinkelbach, para alocação de potência entre Alice e o relay. A alocação de potência é utilizada visando maximizar a eficiência energética segura, medida em bits seguros/J/Hz, ou o throughput seguro, medido em bits seguros/s/Hz. Em relação aos protocolos, consideramos o caso onde Alice tem conhecimento perfeito do estado instantâneo do canal apenas em relação aos usuários legítimos. Desta forma, empregamos o protocolo Decode-and-Forward Seletivo (SDF), que realiza a escolha entre o melhor tipo de comunicação entre Alice e Bob (comunicação direta ou cooperativa) de forma a aumentar a segurança do sistema. Para comparação, consideramos outros esquemas clássicos de cooperação como o Amplify-and-Forward (AF), Decode-and-Forward Fixo (DF) e o Cooperative Jamming (CJ). Nossos resultados demostram que o SDF supera o AF, o DF e o CJ em grande parte das situações. Contudo, quando a taxa de transmissão aumenta ou quando Eve está muito próxima aos nós legítimos, o CJ apresenta um melhor desempenho.We investigate the secure energy efficiency and throughput in cooperative wireless communications systems, in which a pair of legitimate users (Alice and Bob) are assisted by a relay node and the communication occurs in the presence of a passive eavesdropper (Eve). Several cooperative protocols are compared with respect to these measures and we use of an iterative and distributed algorithm, based on Dinkelbach algorithm, to allocate power between Alice and the relay. The power allocation is performed in order to increase the secure energy efficiency, measured in secure bits/J/Hz, or secure throughput, measured in secure bits/s/Hz. About the protocols, we consider the case where Alice has perfect knowledge only about the instantaneous channel state of the legitimate channel. So, we employ a Selective Decode-and-Forward (SDF) protocol, which chooses the best type of communication between Alice and Bob (direct or cooperative communication) in order to improve security. For comparison, we consider other classical cooperative schemes such as the Amplify-and-Forward (AF), the Fixed Decode-and-Forward (DF) and the Cooperative Jamming (CJ). Our results show that SDF outperforms AF, DF and CJ in most situations. However, when the transmit rate increases or when Eve is close to the legitimate nodes, CJ has a better performance.
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Okumu, Elizabeth Mukhwana. "Performance evaluation of cross-layer energy-efficient transmit antenna selection for spatial multiplexing systems." Doctoral thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/28111.
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Abstract Multiple-input multiple-output (MIMO) and cognitive radio (CR) are key techniques for present and future high-speed wireless technologies. On the other hand, there are rising energy costs and greenhouse emissions associated with the provision of high-speed wireless communications. Consequently, the design of high-speed energy efficient systems is paramount for next-generation wireless systems. This thesis studies energy-efficient antenna selection for spatial multiplexing multiple-antenna systems from a cross-layer perspective, contrary to the norm, where physical-layer energy efficiency metrics are optimized. The enhanced system performance achieved by cross-layer designs in wireless networks motivates this research. The aim of the thesis is to propose and analyze novel cross-layer energy-efficient transmit antenna selection schemes that enhance energy efficiency and system performance - with regard to throughput, transmission latency, packet error rate and receiver buffer requirements. Firstly, this thesis derives the analytical expression for data link throughput for point-to-point spatial multiplexing multiple-antenna systems - which include MIMO and underlay CR MIMO systems - equipped with linear receivers with N-process stop-and-wait (N-SAW) as the automatic repeat request (ARQ) protocol. The performance of cross-layer transmit antenna selection, which maximizes the derived throughput metric, is then analyzed. The impact of packet size, number of SAW processes and the stalling of packets inside the receiver reordering buffer is considered in the investigation. The results show that the cross-layer approach, which takes into account system characteristics at both the data link and physical layers, has superior performance in comparison with the conventional physical-layer approach, which optimizes capacity. Secondly, this thesis proposes a cross-layer energy efficiency metric, based on the derived system throughput. Energy-efficient transmit antenna selection for spatial multiplexing MIMO systems, which maximizes the proposed cross-layer energy efficiency metric, by jointly optimizing the transmit antenna subset and transmit power, subject to spectral efficiency and transmit power constraints, is then introduced and analyzed. Additionally, adaptive modulation is incorporated into the proposed cross-layer scheme to enhance system performance. Cross-layer energyefficient transmit antenna selection for underlay CR MIMO systems, where interference constraints now come into play, is then considered. Lastly, this thesis develops novel reduced complexity versions of the proposed cross-layer energyefficient transmit antenna selection schemes - along with detailed complexity analysis - which shows that the proposed cross-layer approach attains significant energy efficiency and performance gains at affordable computational complexity.
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Kailas, Aravind. "Toward perpetual wireless networks: opportunistic large arrays with transmission thresholds and energy harvesting." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34720.
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Solving the key issue of sustainability of battery-powered sensors continues to attract significant research attention. The prevailing theme of this research is to address this concern using energy-efficient protocols based on a form of simple cooperative transmission (CT) called the opportunistic large arrays (OLAs), and intelligent exploitation of energy harvesting and hybrid energy storage systems (HESSs). The two key contributions of this research, namely, OLA with transmission threshold (OLA-T) and alternating OLA-T (A-OLA-T), offer an signal-to-noise ratio (SNR) advantage (i.e., benefits of diversity and array (power) gains) in a multi-path fading environment, thereby reducing transmit powers or extending range. Because these protocols do not address nodes individually, the network overhead remains constant for high density networks or nodes with mobility. During broadcasting across energy-constrained networks, while OLA-T saves energy by limiting node participation within a single broadcast, A-OLA-T optimizes over multiple broadcasts and drains the the nodes in an equitable fashion. Another important contribution of this research is the design and analysis of a novel routing metric called communications using HESS (CHESS), which extends the rechargeable battery (RB)-life by relaying exclusively with supercapacitor (SC) energy, and is asymptotically optimal with respect to the number of nodes in the network.
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Milla, Ximena M. "Building Energy Management Systems Technology for HVAC, Lighting and Outlets with Smart Sensor Networks." Thesis, California State University, Long Beach, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=10978010.
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This study was conducted as part of California State University of Long Beach (CSULB) Research Foundation project tittle “Internet of Things (IoT) and Ubiquitous Sensing in University Building Energy Management: Design, Optimization and Technology Demonstration” funded by the California Energy Commission (CEC) EEETD grant and led by Dr. Massoud Nazari. The Emerging Energy Efficient Technology Demonstrations (EEETD) grant of the CEC is aimed to demonstrate and market the deployment of innovative pre-commercial energy efficiency technologies in existing buildings to promote early adoption of energy efficiency systems that will reduce energy consumption as well as costs for the building owner.
Despite the technological advancements for building management systems the actual market penetration is still relatively small in the commercial sector. One of the reasons for not investing on upgrades includes informational awareness. In the hopes to aid in that particular aspect, the following study provides a breakdown of the process for the commissioning of the new management system and demonstrates the scalability of the overall project by first focusing on the existing building such as identifying the building’s energy end uses and circuit configuration for lighting, HVAC, and plug loads. Second, it details the customization for the new EMS, and the interoperability of the new smart devices and network architecture.
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Liu, Jiashang. "Resource Allocation and Energy Management in Green Network Systems." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587577356321898.
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MARTINS, Cláudio Roberto Medeiros de Azevedo Braga. "ALOCAÇÃO DOS CUSTOS DO SISTEMA DE TRANSMISSÃO DE ENERGIA ELÉTRICA CONSIDERANDO A SEGURANÇA." Universidade Federal do Maranhão, 2013. http://tedebc.ufma.br:8080/jspui/handle/tede/1776.
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After implantation of the new economic model for power systems, a fair remuneration strategy of transmission companies has become a matter of great importance. This remuneration should be performed by system users, who must pay proportionally to its network usage. However, there is still no consensus about wich is the best criterion to be adopted to allocate these costs. The most widely used methods take into account the power ows only at normal operating conditions. however, it is recognized that the transmission system is planned and operated to accommodate power also at contingency scenarios, which requires additional transmission capacity. Moreover, part of the idle capacity is due to the characteristics of network investments and uncertainty in relation to demand. Thus, the costs allocated by these methods may not re ect the actual usage of the system. In this context, this work presents a transmission cost allocation method that takes into consideration all these network characteristics. The total costs are decomposed into three components, each of these associated with a part of the transmission capacity of the system and its function. These costs are then allocated based on their system usage in diferent operating scenarios. To validate the proposed method, tests are performed on small and medium power systems. Comparisons are established with some methods more used in the literature, where it is observed that the proposed method provides complete consistency with the expected results for the problem. It was also found that this method offers subsidies to consumers allowing them to define their security requirements.
Com a implantação do novo modelo econômico nos sistemas de potência, a adequada remuneração das empresas provedoras de serviços de transmissão tem se tornado um assunto de grande importância. Esta remuneração deve ser realizada pelos usuários do sistema, que devem pagar proporcionalmente ao seu grau de utilização da rede. No entanto, ainda não há um consenso do melhor critério a ser adotado para alocar estes custos. Os métodos mais utilizados levam em consideração os uxos de potência apenas quando a rede opera em condições normais. No entanto, sabe-se que o sistema de transmissão é planejado e operado para acomodar os uxos também em cenários de contingência, o que exige capacidade adicional de transmissão. Além disso, parte da capacidade ociosa é devido às características dos investimentos no setor e à incerteza em relação à demanda. Desta forma, os custos alocados por estes métodos pode não re etir a real utilização do sistema. Neste contexto, este trabalho apresenta um método de alocação dos custos pelo uso da transmissão que leva em consideração todas estas características da rede. Os custos totais são decompostos em três componentes, cada uma destas relacionada com parte da capacidade de transmissão do sistema e sua função. Estes custos são então alocados aos usuários da rede com base no seu grau de utilização do sistema em diversos cenários de operação. Para validar o método proposto, são realizados testes em sistemas de potência de pequeno e médio porte. Comparações são estabelecidas com alguns dos métodos mais aplicados na literatura, onde constata-se que o método proposto apresenta total coerência com os resultados esperados pelo problema. Veri ca-se ainda que este método oferece subsídios aos consumidores para que estes possam de nir quais seus requisitos de segurança.
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Das, Choton Kanti. "Smart management strategies of utility-scale energy storage systems in power networks." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2019. https://ro.ecu.edu.au/theses/2209.
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Power systems are presently experiencing a period of rapid change driven by various interrelated issues, e.g., integration of renewables, demand management, power congestion, power quality requirements, and frequency regulation. Although the deployment of Energy Storage Systems (ESSs) has been shown to provide effective solutions to many of these issues, misplacement or non-optimal sizing of these systems can adversely affect network performance. This present research has revealed some novel working strategies for optimal allocation and sizing of utility-scale ESSs to address some important issues of power networks at both distribution and transmission levels. The optimization strategies employed for ESS placement and sizing successfully improved the following aspects of power systems: performance and power quality of the distribution networks investigated, the frequency response of the transmission networks studied, and facilitation of the integration of renewable generation (wind and solar). This present research provides effective solutions to some real power industry problems including minimizationof voltage deviation, power losses, peak demand, flickering, and frequency deviation as well as rate of change of frequency (ROCOF).
Detailed simulation results suggest that ESS allocation using both uniform and non-uniform ESS sizing approaches is useful for improving distribution network performance as well as power quality. Regarding performance parameters, voltage profile improvement, real and reactive power losses, and line loading are considered, while voltage deviation and flickers are taken into account as power quality parameters. Further, the study shows that the PQ injection-based ESS placement strategy performs better than the P injection-based approach (in relation to performance improvement), providing more reactive power compensations. The simulation results also demonstrate that obtaining the power size of a battery ESS (MVA) is a sensible approach for frequency support. Hence, an appropriate sizing of grid-scale ESSs including tuning of parameters Kp and Tip (active part of the PQ controller) assist in improving the frequency response by providing necessary active power. Overall, the proposed ESS allocation and sizing approaches can underpin a transition plan from the current power grid to a future one.
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Natarajan, Sriram. "SURGNET an integrated surgical data transmission system over collaborative networks /." Amherst, Mass. : University of Massachusetts Amherst, 2009. http://scholarworks.umass.edu/theses/257/.
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Najafi, Syed Ahmed Ali. "Energy Harvesting From Overhead Transmission Line Magnetic Fields." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1548448189459464.
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Pagonis, Meletios. "Electrical power aspects of distributed propulsion systems in turbo-electric powered aircraft." Thesis, Cranfield University, 2015. http://dspace.lib.cranfield.ac.uk/handle/1826/9873.
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The aerospace industry is currently looking at options for fulfilling the technological development targets set for the next aircraft generations. Conventional engines and aircraft architectures are now at a maturity level which makes the realisation of these targets extremely problematic. Radical solutions seem to be necessary and Electric Distributed Propulsion is the most promising concept for future aviation. Several studies showed that the viability of this novel concept depends on the implementation of a superconducting power network. The particularities of a superconducting power network are described in this study where novel components and new design conditions of these networks are highlighted. Simulink models to estimate the weight of fully superconducting machines have been developed in this research work producing a relatively conservative prediction model compared to the NASA figures which are the only reference available in the literature. A conceptual aircraft design architecture implementing a superconducting secondary electrical power system is also proposed. Depending on the size of the aircraft, and hence the electric load demand, the proposed superconducting architecture proved to be up to three times lighter than the current more electric configurations. The selection of such a configuration will also align with the general tendency towards a superconducting network for the proposed electric distributed propulsion concept. In addition, the hybrid nature of these configurations has also been explored and the potential enhanced role of energy storage mechanisms has been further investigated leading to almost weight neutral but far more flexible aircraft solutions. For the forecast timeframe battery technology seems the only viable choice in terms of energy storage options. The anticipated weight of the Lithium sulphur technology is the most promising for the proposed architectures and for the timeframe under investigation. The whole study is based on products and technologies which are expected to be available on the 2035 timeframe. However, future radical changes in energy storage technologies may be possible but the approach used in this study can be readily adapted to meet such changes.
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Aguilera, Miguel. "Semantic and Physical Modeling and Simulation of Multi-Domain Energy Systems: Gas Turbines and Electrical Power Networks." Thesis, KTH, Elkraftteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-214532.
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The ITEA3 OpenCPS (Open Cyber-Physical System Model-Driven CertifiedDevelopment) project focuses on interoperability between the Modelica/UnifiedModeling Language (UML)/Functional Mock-up Interface (FMI) standards, improved(co-)simulation execution speed, and verified code generation. The project aims to developa modeling and simulation framework for cyber-physical and multi-domain systems. Oneof the main use cases for the framework, is the multi-domain equation-based modelingand simulation of detailed gas turbine power plants (including the explicit equation-basedmodeling of turbomachinery dynamics) and the electrical power grid.In this work, UML class diagrams based on the Common Information Model (CIM)standard are used to describe the semantics of the electrical power grid. An extension basedon the standard ISO 15926 has been proposed to derive the multi-domain semanticsrequired by the models that integrate the electrical power grid with the detailed gas turbinedynamics.Furthermore, the multi-domain physical modeling and simulation Modelica language hasbeen employed to create the equation-based models of the use case of this project. Acomparative analysis between the Single-Domain and Multi-Domain model responses hasbeen performed both in time and frequency. The results show some interesting differencesbetween the turbine dynamics representation of the commonly used GGOV1 standardmodel and the less simplified model of a gas turbine.Finally, the models from each domain can be exchanged between two differentstakeholders by means of Functional Mock-Up Units (FMUs), defined by the FMIstandard. Promising test results were obtained with different simulation tools that supportthe standard, which demonstrates the feasibility of exchanging unambiguous multi-domainmodels with a detailed gas turbine representation. This shows the potential of the FMIstandard for manufacturers to exchange equation-based multi-domain models, while at thesame time protecting their intellectual property.Projektet ITEA3 OpenCPS (Öppen, certifierad modelldriven utveckling för cyberfysiskasystem) fokuserar på interoperabilitet mellan standarderna för Modelica, Unified ModelingLanguage (UML) och Functional Mock-up Interface (FMI), förbättring av tidsåtgångenför (sam-)simulering, samt verifierad kodgenerering. Projektet syftar till att utveckla enplattform för modellering och simulering av cyberfysiska system och system somrepresenteras av olika sorters fysikaliska modeller (eng. multi-domain modeling). Ett av defrämsta användningsområdena för plattformen är ekvationsbaserad modellering ochsimulering av detaljerade gasturbinmodeller i elkraftverk (inklusive explicitekvationsbaserad modellering av dynamiken mellan termiska och roterande komponenter)som är sammankopplade med kraftsystemet.I detta examenarbete används klassdiagram i UML baserade på standarden för CommonInformation Model (CIM) och komponentdiagram från SysML för att beskrivakraftsystemet. En utvidgning baserat på ISO 15926-standarden föreslås för att härledasemantiken för modeller som integrerar både kraftsystemet och detaljerad dynamik förgasturbiner.Vidare så har Modelica, ett språk för modellering och simulering av olikartade fysikaliskasystem, utnyttjats för att skapa ekvationsbaserade modeller som utvecklats i detta projekt.En komparativ analys har genomförts för en detaljerad modell med termodynamik och enförenklad modell genom undersökning av både frekvenssvar och tidssimuleringar.Resultaten visar att skillnader uppstår mellan den detaljerade modellen och den ikraftsystemsammanhang allmänt använda modellen GGOV1, vilket kan förklaras medförenklingar i den snareSlutligen kan modeller från olika fysikaliska domäner utbytas mellan intressenter med s.k.Functional Mock-Up Units (FMU-enheter), som definieras av FMI-standarden. Lovanderesultat uppnåddes med simuleringsverktyg som stöder FMI-standarden vilket visarmöjligheten till ett otvetydigt utbyte av detaljerade gasturbinmodeller och elkraftsmodeller.Detta visar potentialen i FMI-standarden för modellutbyte mellan olikamodelleringsdomäner, vilket skulle kunna låta tillverkare att dela ekvationsbaserademodeller utan att ge upp immateriella tillgångar.
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Zhou, Lin. "Energy efficient transmitter design with compact antenna for future wireless communication systems." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33104.
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This thesis explores a novel technique for transceiver design in future wireless systems, which is cloud radio access networks (CRANs) with single radio frequency (RF) chain antennas at each remote radio head (RRH). This thesis seeks to make three contributions. Firstly, it proposes a novel algorithm to solve the oscillatory/unstable behaviour of electronically steerable parasitic array radiators (ESPAR) when it provides multi-antenna functionality with a single RF chain. This thesis formulates an optimization problem and derives closed-form expressions when calculating the configuration of an ESPAR antenna (EA) for arbitrary signals transmission. This results in simplified processing at the transmitter. The results illustrate that the EA transmitter, when utilizing novel closed-form expressions, shows significant improvement over the performance of the EA transmitter without any pre-processing. It performs at nearly the same symbol error rate (SER) as standard multiple antenna systems. Secondly, this thesis illustrates how a practical peak power constraint can be put into an EA transceiver design. In an EA, all the antenna elements are fed centrally by a single power amplifier. This makes it more probable that during use, the power amplifier reaches maximum power during transmission. Considering limited power availability, this thesis proposes a new algorithm to achieve stable signal transmission. Thirdly, this thesis shows that an energy efficiency (EE) optimization problem can be formulated and solved in CRANs that deploy single RF chain antennas at RRHs. The closed-form expressions of the precoder and power allocation schemes to transmit desired signals are obtained to maximise EE for both single-user and multi-user systems. The results show that the CRANs with single RF chain antennas provide superior EE performance compared to the standard multiple antenna based systems.
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Sudhakaran, Sujith. "Impact of Renewable Energy Installations and Utilisation of Smart Energy Management Systems on low-voltage networks- a study case at Östergarnslandet, Gotland." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-396208.
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This thesis carries out an analysis of PV panel installations in the region of Östergarnslandet, situated in the Swedish island of Gotland. A low-voltage grid of 0.4 kV in the region is examined with the help of software Open DSS. This is done with the data provided by the distribution grid owner, Gotlands Elnät AB (GEAB). The potential impacts created by the PV installations in terms of exceeding currents, voltages and harmonics are assessed and thereby the hosting capacity of Solar PV in the houses and on the whole grid is studied. Moreover, a theoretical review of the Smart Energy Management System (SEMS) is investigated about the performance and the devices involved in the system. Also, a battery which is a part of SEMS is modelled, taking into account the production and consumption of a single household connected in the grid. The battery sizes for various PV installations at the home is suggested via NPV analysis with the intention to increase the self-consumption and to reduce the cost of the electricity bill. In addition, a survey is conducted in the region with support from the Department of Earth Sciences, Uppsala University Campus Gotland. The survey is made to determine the attitude of the people in Östergarnslandet towards an energy transition. The results show that the maximum amount that can be installed or the hosting capacity of solar in the studied grid is 120 kW. From the simulations, it shows that the impacts created by these PV installations do not violate the specified Grid norms. From the theoretical analysis, SEMS is found to be a better solution for energy management at homes. The performance study done shows that 33 % of the solar energy produced in the home is directly used at the time of production. The remaining energy is used for battery charging for the future supply of power and feeding to the grid. The battery modelled for 10- kW PV installation in the home is found to be 9-kWh and the same for a 15-kW installation. Meanwhile, for a 20- kW installation, a 15-kWh battery is found to be ideal from the study. The survey conducted in the region has turned out to be positive as people are supportive of the energy transition. The responders have marked photovoltaics as the prime option for investment in energy production which assures that it has a good future in the area.
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Fernandez, Irma Becerra. "Encryption-based security for public networks : technique and application." FIU Digital Commons, 1994. http://digitalcommons.fiu.edu/etd/3296.
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This dissertation describes the development of a new system whereby the Public Switch Telephone Network (PSTN), which is not secure, can perform like a private network. Integrated Services Digital Network (ISDN) forms a technical platform for other communication technologies, such as frame relay and Switched Megabit Data Service (SMDS). This is an original and innovative hardware and software design which can be embedded into the ISDN Customer Premises Equipment (CPE) to privatize the public ISDN without the need to upgrade the existing switching equipment. This research incorporates original design and development of the following hardware and software modules to provide real-time encryption and decryption of images and data in the ISDN medium: 1. ISDN Communications Module with customized Caller-ID access. 2. Token Access Control module for secure log-in. 3. A Hybrid Cryptographic Module, public key for key management and authentication, and private key for privacy. This Cryptographic module, the Security Extension Module to the Terminal Adapter (SEMTA), was implemented in software, and then optimized in hardware. This work proves that medical images and legal documents can be transmitted through the PSTN without any security breach, guaranteeing the privacy, confidentiality, and authenticity of the data.
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Lim, Kok Seng. "Analysis of network management protocols in optical networks." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Mar%5FLim%5FK.pdf.
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Krishnan, Narayanan. "Analysis of energy efficiency of cooperative MIMO schemes." Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/1427.
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Hariharan, Srikanth. "Communication-Efficient Convergecasting for Data Fusion in Wireless Sensor Networks." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1317672795.
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Suzuki, Nayara Yuko. "Estudo de controle e proteção para sistemas de transmissão HVDC multiterminais baseados em conversores modulares multiníveis." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-20092018-112205/.
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O crescente interesse por sistemas de transmissão do tipo VSC-based HVDC (VSCHVDC) como alternativa aos atuais tem levado à necessidade de estudos sobre o principal desafio associado à sua implantação, que é o desenvolvimento de um esquema de proteção que seja rápido e que identifique a zona de proteção na qual uma eventual falta tenha ocorrido, respeitando-se assim o princípio de seletividade. Para estudo de um sistema de proteção que atenda a estes requisitos, foi utilizada neste trabalho uma rede com quatro terminais e transmissão High-Voltage Direct Current (HVDC), implementada com conversores modulares multiníveis (Modular Multilevel Converter (MMC)) e simulada em situações de contingência. Grandezas medidas nos elos de Corrente Contínua (CC) ligados a um dos terminais foram utilizadas para identificar a ocorrência de uma contingência na rede e então para decidir se trata-se de uma falta interna à zona de proteção considerada na análise. Para classificar as faltas em interna ou externa, observaram-se os espectros dos sinais de tensão CC em um terminal, calculados sobre uma janela do sinal através de Fast Fourier Transform (FFT), para várias situações de falta. Destes espectros, notou-se que uma característica varia de acordo com a distância da falta até o terminal, com o fato de a falta ser interna ou externa e com a resistência de falta. Através desta característica, denominada aqui \"frequência de centro de massa\", foi possível distinguir as faltas internas com resistências de falta baixas do restante dos eventos testados. Considerando-se apenas este parâmetro, não foi possível classificar corretamente faltas internas com resistência de falta muito alta.The growing interest in VSC-based HVDC (VSC-HVDC) transmission systems as an alternative to the current ones has required studies about the the main challenge associated with its application, which is the development of a protection scheme that is able to both fast and efficiently determine the protection zone where a fault may have happened so as to achieve selectivity. In order to study a protection system that complies with those requirements, a High-Voltage Direct Current (HVDC) transmission system with four terminals implemented with Modular Multilevel Converter (MMC) converters was simulated under contingency condition. Electrical quantities measured in one of the terminal\'s Direct Current (DC) links were used to determine the occurrence of a fault event in the system, as well as to decide whether that event belonged to the protection zone considered in the analysis. Spectra obtained via Fast Fourier Transform (FFT) over a window of the DC voltage measured in one of the terminals were observed in order to discriminate between internal and external fault events. From these observations, it was noticed that a certain characteristic, named here \"center of mass frequency\", varies according to the distance between the fault location and the terminal, fault resistance, as well as whether that the fault is either internal or external to the analysed protection zone. By using this characteristic, it was possible to tell internal faults with low resistance fault from other events. Considering this parameter only, it was not possible to correctly classify internal faults with high fault resistance.
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Thanayankizil, Lakshmi. "Opportunistic large array (OLA)-based routing for sensor and adhoc wireless networks." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50374.
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An Opportunistic Large Array (OLA) is a form of cooperative diversity in which a large group of simple, inexpensive relays operate without any mutual coordination, but naturally fire together in response to the energy received from a single source or another OLA. The main contributions of this thesis are the introduction of two OLA-based routing protocols: OLA Concentric Routing Algorithm (OLACRA), which is an upstream routing algorithm suitable for static wireless sensor networks (WSNs), and OLA Routing On-Demand (OLAROAD), which is a robust reactive routing scheme suitable for mobile ad hoc networks (MANETs). In fixed multi-hop wireless sensor networks with a single sink, where energy conservation is often a concern, simulations of the new algorithms show as much as 80% of the transmit energy required to broadcast data can be saved, relative to existing OLA-based broadcasting approaches. In MANETs, where robustness of the routes is an important performance indicator, OLAROAD-based cooperative routes last much longer compared to their state-of-art multi-hop non-cooperative transmission (CT)-based counterparts. However, OLACRA and OLAROAD have higher node participation, and thereby lower throughput, in comparison with the non-CT schemes. To improve the throughput, and thereby bandwidth utilization, the properties of uplink OLAs and their suppression regions are carefully studied. Based on the observations, Hop-Optimized OLACRA (HOLA), which is a variant of OLACRA, and has the maximum bandwidth utilization amongst all the OLA unicast schemes studied, is proposed. HOLA routes have bandwidth utilization comparable to non-CT schemes, but a much lower (~10 dB less) transmit power per node.
The last section of this thesis treats the MAC design for OLA-based networks. In contrast to non-CT networks, a 802.11-based RTS/CTS MAC scheme is shown to reduce the reliability in OLA unicast schemes. A distributed cluster-head-based MAC scheme for channel reservation and OLA Size Adaptation Mechanism for link repair/maintenance are proposed for OLA-based networks. The performances of these protocols are shown to be comparable to a non-CT multihop scheme using the RTS/CTS/DATA/ACK handshake-based link layer design.
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Qu, Yipeng. "Wireless Sensor Network Deployment." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/854.
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Wireless Sensor Networks (WSNs) are widely used for various civilian and military applications, and thus have attracted significant interest in recent years. This work investigates the important problem of optimal deployment of WSNs in terms of coverage and energy consumption. Five deployment algorithms are developed for maximal sensing range and minimal energy consumption in order to provide optimal sensing coverage and maximum lifetime. Also, all developed algorithms include self-healing capabilities in order to restore the operation of WSNs after a number of nodes have become inoperative.
Two centralized optimization algorithms are developed, one based on Genetic Algorithms (GAs) and one based on Particle Swarm Optimization (PSO). Both optimization algorithms use powerful central nodes to calculate and obtain the global optimum outcomes. The GA is used to determine the optimal tradeoff between network coverage and overall distance travelled by fixed range sensors. The PSO algorithm is used to ensure 100% network coverage and minimize the energy consumed by mobile and range-adjustable sensors. Up to 30% - 90% energy savings can be provided in different scenarios by using the developed optimization algorithms thereby extending the lifetime of the sensor by 1.4 to 10 times.
Three distributed optimization algorithms are also developed to relocate the sensors and optimize the coverage of networks with more stringent design and cost constraints. Each algorithm is cooperatively executed by all sensors to achieve better coverage. Two of our algorithms use the relative positions between sensors to optimize the coverage and energy savings. They provide 20% to 25% more energy savings than existing solutions. Our third algorithm is developed for networks without self-localization capabilities and supports the optimal deployment of such networks without requiring the use of expensive geolocation hardware or energy consuming localization algorithms. This is important for indoor monitoring applications since current localization algorithms cannot provide good accuracy for sensor relocation algorithms in such indoor environments. Also, no sensor redeployment algorithms, which can operate without self-localization systems, developed before our work.
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Chen, Sheng. "Future development trends of optical transport network infrastructure an infrastructural framework for metropolitan-based optical transport networks : a field test of a Chinese ISP and a case study of a Chinese electrical power company /." Access electronically, 2006. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20070822.115714/index.html.
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Ha, Rick Wan Kei. "A Sleep-Scheduling-Based Cross-Layer Design Approach for Application-Specific Wireless Sensor Networks." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/918.
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The pervasiveness and operational autonomy of mesh-based wireless sensor networks (WSNs) make them an ideal candidate in offering sustained monitoring functions at reasonable cost over a wide area. To extend the functional lifetime of battery-operated sensor nodes, stringent sleep scheduling strategies with communication duty cycles running at sub-1% range are expected to be adopted. Although ultra-low communication duty cycles can cast a detrimental impact on sensing coverage and network connectivity, its effects can be mitigated with adaptive sleep scheduling, node deployment redundancy and multipath routing within the mesh WSN topology. This work proposes a cross-layer organizational approach based on sleep scheduling, called Sense-Sleep Trees (SS-Trees), that aims to harmonize the various engineering issues and provides a method to extend monitoring capabilities and operational lifetime of mesh-based WSNs engaged in wide-area surveillance applications. Various practical considerations such as sensing coverage requirements, duty cycling, transmission range assignment, data messaging, and protocol signalling are incorporated to demonstrate and evaluate the feasibility of the proposed design approach.
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Parvez, Imtiaz. "Spectrum Sharing, Latency, and Security in 5G Networks with Application to IoT and Smart Grid." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3879.
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The surge of mobile devices, such as smartphones, and tables, demands additional capacity. On the other hand, Internet-of-Things (IoT) and smart grid, which connects numerous sensors, devices, and machines require ubiquitous connectivity and data security. Additionally, some use cases, such as automated manufacturing process, automated transportation, and smart grid, require latency as low as 1 ms, and reliability as high as 99.99\%. To enhance throughput and support massive connectivity, sharing of the unlicensed spectrum (3.5 GHz, 5GHz, and mmWave) is a potential solution. On the other hand, to address the latency, drastic changes in the network architecture is required. The fifth generation (5G) cellular networks will embrace the spectrum sharing and network architecture modifications to address the throughput enhancement, massive connectivity, and low latency.
To utilize the unlicensed spectrum, we propose a fixed duty cycle based coexistence of LTE and WiFi, in which the duty cycle of LTE transmission can be adjusted based on the amount of data. In the second approach, a multi-arm bandit learning based coexistence of LTE and WiFi has been developed. The duty cycle of transmission and downlink power are adapted through the exploration and exploitation. This approach improves the aggregated capacity by 33\%, along with cell edge and energy efficiency enhancement. We also investigate the performance of LTE and ZigBee coexistence using smart grid as a scenario.
In case of low latency, we summarize the existing works into three domains in the context of 5G networks: core, radio and caching networks. Along with this, fundamental constraints for achieving low latency are identified followed by a general overview of exemplary 5G networks. Besides that, a loop-free, low latency and local-decision based routing protocol is derived in the context of smart grid. This approach ensures low latency and reliable data communication for stationary devices.
To address data security in wireless communication, we introduce a geo-location based data encryption, along with node authentication by k-nearest neighbor algorithm. In the second approach, node authentication by the support vector machine, along with public-private key management, is proposed. Both approaches ensure data security without increasing the packet overhead compared to the existing approaches.
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Nilsson, Martin. "On Efficient Transmission Balancing Operation : Capturing the Normal State Frequency and Active Power Dynamics." Licentiate thesis, KTH, Elkraftteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-221221.
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In an electric power system, there will always be an electric balance. Nevertheless, System Operators (SOs) often uses the term imbalance. Here, the term imbalance refers to the difference between trades and real-time measurements. This thesis defines the term imbalance and develops a framework helping SOs in finding better decisions controlling these imbalances. Imbalances are controlled by many decisions made at various stages before real-time. A decision can be to increase the flexibility in production and consumption. However, this is not the only decision affecting real-time balancing operation. Other decisions are grid code requirements, such as ramp rates of HVDC and generation; balancing market structure, such as imbalance fees and trading period lengths; and the strategies used in the system-operational dispatch. The purpose of this thesis is to create a new possibility for SO to find decisions improving the balancing operation. In order to find and compare decisions, the thesis develops a framework that evaluates many different decisions made at various stages before real-time. The framework consists of the following. First, it develops an intra-hour model using multi-bidding zone data from a historical time-period; able to capture the normal state frequency and active power dynamics. The model creates high-resolution data from low-resolution measurements using several data-processing methods. The uncertainty from the historical time-period is re-created using many sub-models with different input data, time-scales and activation times of reserves. Secondly, the framework validates the model and identifies system parameters based on simulated frequencies and frequency measurements in the normal state operation. Finally; new decisions' are modelled, tested, and evaluated on their impact on selected targets supporting corporate missions of the SOs. The goal of the framework is that it should be able to find better decisions for balancing operation but also that it should be applicable for real and large power systems. To verify this, the framework is tested on a synchronous area containing 11 bidding zones in northern Europe. Results show that the framework can be validated and trusted. Three new decisions, made at various stages before real time, have been modelled, tested and evaluated. The modelled decisions were (i) lower ramp rates for generation, (ii) increased capacities for automatic reserves, and (iii) a new strategy for the system-operational dispatch. One implication of applying the balancing evaluation framework on data from July 2015 is that all tested decisions improve several selected targets supporting the corporate missions of the SOs. The conclusion is that the balancing framework is useful as a simulation tool in helping SOs in finding more efficient decisions for transmission system balancing operation.QC 20180116
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Tonin, Fabianna Stumpf. "Caracterização de sistemas fotovoltaicos conectados à rede elétrica na cidade de Curitiba." Universidade Tecnológica Federal do Paraná, 2017. http://repositorio.utfpr.edu.br/jspui/handle/1/2876.
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Na busca por novas opções para a constituição da matriz energética brasileira, os Sistemas Fotovoltaicos Conectados à Rede Elétrica (SFVCR) configuram-se como uma alternativa para os centros urbanos, pois permitem a geração de energia de modo distribuído, ou seja, no próprio local onde esta será consumida e, permitem também, com que o excedente de energia produzido seja injetado na rede elétrica. Diante da perspectiva de instalar o SFVCR, o objetivo desta pesquisa foi o de elaborar um estudo específico, detalhado e atualizado sobre o potencial de geração de energia na cidade de Curitiba. Neste trabalho apresenta-se o estudo de caso de seis sistemas fotovoltaicos instalados em Curitiba, os quais tiveram seus Índices de Mérito – Produtividade, Taxa de Desempenho e Fator de Capacidade - avaliados, a partir dos dados de geração de energia elétrica destes sistemas, e dos dados de irradiação obtidos do Instituto Nacional de Meteorologia (INMET). O estudo revelou que, até abril de 2017, o estado do Paraná possuía 810 SFVCR em operação, correspondendo a um total de 5MW e, a cidade de Curitiba 170 SFVCR – 865 kW em operação, sendo que 80% dos sistemas estão instalados em residências. Outro fato interessante é que 98% desses sistemas usam módulos com tecnologia de silício policristalino, 75% aplicam inversores monofásicos e, 95% desses inversores não possuem transformadores, pois dessa forma as perdas no processo de conversão são menores, além desses equipamentos serem mais compactos e possuírem tecnologia mais avançada do que os inversores com transformador. Constatou-se que a principal tendência do mercado de energia fotovoltaica é empregar inversores sem transformador. Além disso, os estudos realizados revelaram que a escolha do inversor e o modo de instalação dos painéis fotovoltaicos são fatores determinantes para maximizar o desempenho do sistema fotovoltaico. Os resultados desta pesquisa mostram a importante contribuição que os SFVCR podem trazer na geração de energia de modo distribuído e dessa forma, podem colaborar para a elaboração de políticas públicas com o intuito de incentivar projetos e pesquisas na área de energia fotovoltaica, visando à disseminação do uso dessa fonte renovável no país.In the search for new options for the establishment of the energy matrix of Brazil, the Grid-Connected Photovoltaic Systems (SFVCR) are configured as an alternative to urban centers, because they allow the power generation at distributed mode, that is, generate energy at the place where it will be consumed and inject the surplus energy into the network. Faced with the prospect of installing Grid-Connected Photovoltaic System, the objective of this research is to characterize this type of photovoltaic system and also, analyze the results in terms of productivity parameters, such as Yield, Performance Ratio and Capacity Factor of six grid-connected systems that are installed in Curitiba. The radiation data used to calcute those parameters has been acquired from Instituto Nacional de Meteorologia (INMET). This paper highlight that the Parana state has 810 SFVCR (until April 2017) in operation, which stands for 5MW and Curitiba has 170 SFVCR, 865 kW in operation, and 80% of them are installed in residences. In addition, 98% of those systems use multicrystalline modules, 75% use single phase inverters and 95% of these use inverters transformerless, because the losses in the conversion process are reduced and the equipments are more compact and have more technology than the inverters with transformer. So, the main trend of photovoltaic energy market is to use transformerless inverters. The results obtained shows that the inverters’choice and the installation mode of the photovoltaic modules are important factors to maximize the photovoltaic system’s performance. In the end, the results demonstrates that the SFVCR contribute to distributed power generation and should be use in the elaboration of public policies with the purpose of encouraging projects and research in the photovoltaic energy’s area, aiming the dissemination of this renewable source of energy in Brazil.
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He, Shengyang. "Modeling power system load using intelligent methods." Thesis, Kansas State University, 2011. http://hdl.handle.net/2097/12036.
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Master of ScienceDepartment of Electrical Engineering
Shelli K. Starrett
Modern power systems are integrated, complex, dynamic systems. Due to the complexity, power system operation and control need to be analyzed using numerical simulation. The load model is one of the least known models among the many components in the power system operation. The two different load models are the static and dynamic models. The ZIP load model has been extensively studied. This has widely applied to composite load models that could maintain constant impedance, constant current, and/or constant power. In this work, various Neural Networks algorithms and fuzzy logic have been used to obtain these ZIP load model coefficients for determining the percentage of constant impedance, current, or power for the various load buses. The inputs are a combination of voltage, voltage change, and power change, or voltage and power, and the outputs consist of the ZIP load model coefficients for determining the type and the percentage of load at the bus. The trained model is used to predict the type and percentage of constant load at other buses using simulated transient data from the 16-generator system. A small study was also done using a dynamic induction machine model in addition to the ZIP load model. As expected, the results show that the dynamic model is more difficult to determine than the static model.
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Yan, Zhaohui. "Performance Analysis of A Banyan Based ATM Switching Fabric with Packet Priority." PDXScholar, 1995. https://pdxscholar.library.pdx.edu/open_access_etds/5199.
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Since the emergence of the Asynchronous Transfer Mode ( A TM ) concept, various switching architectures have been proposed. The multistage interconnection networks have been proposed for the switching architecture under the A TM environment. In this thesis, we propose a new model for the performance analysis of an A TM switching fabric based on single-buffered Banyan network. In this model, we use a three-state, i.e., "empty", "new" and "blocked" Markov chain model to describe the behavior of the buffer within a switching element. In addition to traditional statistical analysis including throughput and delay, we also examine the delay variation. Performance results show that the proposed model is more accurate in describing the switch behavior under uniform traffic environment in comparison with the "two-state" Markov chain model developed by Jenq, et. al.[4] [6] . Based on the "three-state" model, we study a packet priority scheme which gives the blocked packet higher priority to be routed forward during contention. It is found that the standard deviation of the network delay is reduced by about 30%.
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Ramadhani, Umar Hanif. "Uncertainty and correlation modeling for load flow analysis of future electricity distribution systems : Probabilistic modeling of low voltage networks with residential photovoltaic generation and electric vehicle charging." Licentiate thesis, Uppsala universitet, Byggteknik och byggd miljö, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-434951.
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The penetration of photovoltaic (PV) and electric vehicles (EVs) continues to grow and is predicted to claim a vital share of the future energy mix. It poses new challenges in the built environment, as both PV systems and EVs are widely dispersed in the electricity distribution system. One of the vital tools for analyzing these challenges is load flow analysis, which provides insights on power system performance. Traditionally, for simplicity, load flow analysis utilizes deterministic approaches and neglecting correlation between units in the system. However, the growth of distributed PV systems and EVs increases the uncertainties and correlations in the power system and, hence, probabilistic methods are more appropriate. This thesis contributes to the knowledge of how uncertainty and correlation models can improve the quality of load flow analysis for electricity distribution systems with large numbers of residential PV systems and EVs. The thesis starts with an introduction to probabilistic load flow analysis of future electricity distribution systems. Uncertainties and correlation models are explained, as well as two energy management system strategies: EV smart charging and PV curtailment. The probabilistic impact of these energy management systems in the electricity distribution system has been assessed through a comparison of allocation methods and correlation analysis of the two technologies. The results indicate that these energy management system schemes improve the electricity distribution system performance. Furthermore, an increase in correlations between nodes is also observed due to these schemes. The results also indicate that the concentrated allocation has more severe impacts, in particular at lower penetration levels. Combined PV-EV hosting capacity assessment shows that a combination of EV smart charging with PV curtailment in all buildings can further improve the voltage profile and increase the hosting capacity. The smart charging scheme also increased the PV hosting capacity slightly. The slight correlation between PV and EV hosting capacity shows that combined hosting capacity analysis of PV systems and EVs is beneficial and is suggested to be done in one framework. Overall, this thesis concludes that an improvement of uncertainty and correlation modeling is vital in probabilistic load flow analysis of future electricity distribution systems.
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Barbosa, Carlos David Franco 1956. "Impactos do desempenho das emendas dos cabos de linhas de transmissão na confiabilidade de redes elétricas." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258416.
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Orientadores: Alberto Luiz Francato, Carlos Alberto MariotoniTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
Made available in DSpace on 2018-08-18T13:32:01Z (GMT). No. of bitstreams: 1 Barbosa_CarlosDavidFranco_D.pdf: 7182306 bytes, checksum: 6a8fd84aba169e2fceffb93e27a4c5b5 (MD5) Previous issue date: 2011
Resumo: Esta tese tem como objetivo estudar métodos de planejamento da expansão da transmissão de energia elétrica em mercados de eletricidade re-estruturados, tanto em um ambiente tradicional quanto com a adoção de inovações tecnológicas. No trabalho são estudados procedimentos de campo para as linhas de transmissão, considerando economia e confiabilidade, principalmente em emendas a compressão para cabos ACSR (Aluminum Core Steel Reinforced). O trabalho descreve os resultados de pesquisas efetuadas com fabricantes e concessionárias usuárias das emendas a compressão e ainda sugere alguns procedimentos e rotinas de inspeções para melhorar a confiabilidade do sistema. Os resultados dos testes com as emendas, realizados em laboratório, serviram para dar suporte para a analise de falhas, subsidiando a avaliação das causas de falhas mais frequentes no ambiente competitivo. Por fim foram apresentadas tecnologias emergentes com possibilidade de redução da taxa de falhas nos sistemas de transmissão de energia elétrica bem como as recomendações de boas praticas para o setor
Abstract: This thesis has as objective to study electricity transmission expansion planning In re-structured markets, both traditional as well as with technological innovations. In the work are studied transmission lines field procedures considering economy and reliability, mainly ACSR (Aluminum Core Steel Reinforced) compression splices. The work describes compression splices field surveys with suppliers and users concessionaries and also suggest some procedures and inspections routines to improve system reliability. The results of laboratory splice tests helped the failure analysis and frequently failure causes on competitive environment. Finally it is presented emerging technologies with failure reduction possibilities for the electricity transmission systems and good practices recommendations for sector
Doutorado
Recursos Hidricos, Energeticos e Ambientais
Doutor em Engenharia Civil
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Ruiz, Gomez Lina Maria. "Intégration de la production éolienne aux réseaux électriques : approches techniques et économiques." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENT089/document.
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La Directive européenne et les politiques de prévention du changement climatique conduisentà un développement important des Énergies Renouvelables pour la production d'électricité. Cecontexte politique est en train d'induire l'insertion massive de production intermittente d'origineéolien dans les réseaux électriques. Pour répondre à la question des limites de l'intégration de l'éoliendans les réseaux électriques, nous nous appuyons sur l'étude des aspects technique et économiques.Dans ce cadre, cette thèse s'intéresse d'une part à l'étude de l'efficacité des dispositifs d'incitationéconomique du point de vue de leur efficacité à stimuler la croissance de l'énergie éolienne et d'autrepart, aux problématiques techniques de court et long terme liées à l'intermittence de l'éolien. Dans lecourt-terme, les problèmes du réseau électrique ainsi que les ajustements dans le marché del'électricité sont abordés. Dans le long terme, l'impact de l'éolien sur la sûreté de fonctionnement estévalué au moyen d'un algorithme de calcul du crédit de capacité de l'éolienThe development of Renewable Energy for electricity production has increased due to theEuropean policies and directives to prevent climate change. This political context is promoting amassive insertion of intermittent wind electricity production into electrical networks. There are stilldoubts about the limitations of integrating wind power into the electrical networks. For this reason,we focus on the study technical and economic aspects to approach these limitations. The firstpurpose of this research is to determine the effectiveness of the economical incentives policies inorder to stimulate growth in the wind power production. The second one is to evaluate the technicalproblems in the short and long term caused by the intermittency of wind power. In the short-term,the problems of power systems as well as the adjustments in the electricity market are discussed. Inthe long term, the impact of wind power reliability (in the network) is evaluated by using an algorithmto calculate the capacity credit of wind power
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Hajimiragha, Amirhossein. "Sustainable Convergence of Electricity and Transport Sectors in the Context of Integrated Energy Systems." Thesis, 2010. http://hdl.handle.net/10012/5153.
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Transportation is one of the sectors that directly touches the major challenges that energy utilities are faced with, namely, the significant increase in energy demand and environmental issues. In view of these concerns and the problems with the supply of oil, the pursuit of alternative fuels for meeting the future energy demand of the transport sector has gained much attention. The future of transportation is believed to be based on electric drives in fuel cell vehicles (FCVs) or plug-in electric vehicles (PEVs). There are compelling reasons for this to happen: the efficiency of electric drive is at least three times greater than that of combustion processes and these vehicles produce almost zero emissions, which can help relieve many environmental concerns. The future of PEVs is even more promising because of the availability of electricity infrastructure. Furthermore, governments around the world are showing interest in this technology by investing billions of dollars in battery technology and supportive incentive programs for the customers to buy these vehicles. In view of all these considerations, power systems specialists must be prepared for the possible impacts of these new types of loads on the system and plan for the optimal transition to these new types of vehicles by considering the electricity grid constraints. Electricity infrastructure is designed to meet the highest expected demand, which only occurs a few hundred hours per year. For the remaining time, in particular during off-peak hours, the system is underutilized and could generate and deliver a substantial amount of energy to other sectors such as transport by generating hydrogen for FCVs or charging the batteries in PEVs. This thesis investigates the technical and economic feasibility of improving the utilization of electricity system during off-peak hours through alternative-fuel vehicles (AFVs) and develops optimization planning models for the transition to these types of vehicles. These planning models are based on decomposing the region under study into different zones, where the main power generation and electricity load centers are located, and considering the major transmission corridors among them. An emission cost model of generation is first developed to account for the environmental impacts of the extra load on the electricity grid due to the introduction of AFVs. This is followed by developing a hydrogen transportation model and, consequently, a comprehensive optimization model for transition to FCVs in the context of an integrated electricity and hydrogen system. This model can determine the optimal size of the hydrogen production plants to be developed in different zones in each year, optimal hydrogen transportation routes and ultimately bring about hydrogen economy penetration. This model is also extended to account for optimal transition to plug-in hybrid electric vehicles (PHEVs). Different aspects of the proposed transition models are discussed on a developed 3-zone test system. The practical application of the proposed models is demonstrated by applying them to Ontario, Canada, with the purpose of finding the maximum potential penetrations of AFVs into Ontario’s transport sector by 2025, without jeopardizing the reliability of the grid or developing new infrastructure. Applying the models to this real-case problem requires the development of models for Ontario’s transmission network, generation capacity and base-load demand during the planning study. Thus, a zone-based model for Ontario’s transmission network is developed relying on major 500 and 230 kV transmission corridors. Also, based on Ontario’s Integrated Power System Plan (IPSP) and a variety of information provided by the Ontario Power Authority (OPA) and Ontario’s Independent Electricity System Operator (IESO), a zonal pattern of base-load generation capacity is proposed. The optimization models developed in this study involve many parameters that must be estimated; however, estimation errors may substantially influence the optimal solution. In order to resolve this problem, this thesis proposes the application of robust optimization for planning the transition to AFVs. Thus, a comprehensive sensitivity analysis using Monte Carlo simulation is performed to find the impact of estimation errors in the parameters of the planning models; the results of this study reveals the most influential parameters on the optimal solution. Having a knowledge of the most affecting parameters, a new robust optimization approach is applied to develop robust counterpart problems for planning models. These models address the shortcoming of the classical robust optimization approach where robustness is ensured at the cost of significantly losing optimality. The results of the robust models demonstrate that with a reasonable trade-off between optimality and conservatism, at least 170,000 FCVs and 900,000 PHEVs with 30 km all-electric range (AER) can be supported by Ontario’s grid by 2025 without any additional grid investments.
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Balibani, Siva Kumar. "Small Signal Stability Analysis of a Power System with a Grid Connected Wind Powered Permanent Magnet Synchronous Generator (PMSG)." Thesis, 2015. http://etd.iisc.ernet.in/2005/3835.
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Small signal oscillation has been always a major concern in the operation of power systems. In a generator, the electromechanical coupling between the rotor and the rest of the system causes it to behave in a manner similar to a spring mass damper system. Following any disturbance, such as sudden change in loads, actuations in the output of turbine and faults etc. it exhibits an oscillatory behaviour around the equilibrium state. The use of fast acting high gain AVRs and evolution of large interconnected power systems with transfer of bulk power across weak transmission links have further aggravated the problem of these low frequency oscillations. Small oscillations in the range of about 0.1Hz to 3.5Hz can persist for long periods, limiting the power transfer capability of the transmission lines. These oscillations can be reduced by incorporating auxiliary controllers on generator excitation system.
Power System Stabilizers (PSSs) were developed to produce additional damping by modulating the generator excitation voltage. Designing effective PSS for all operating conditions especially in large interconnected power systems still remains a difficult and challenging task.
More and more power electronic based controllers have been and will be used in power systems. Many of these controllers such as Static Var Compensators (SVCs), Static Synchronous Compensators (STATCOMs) and Unified Power Flow Controllers (UPFCs) etc., are incorporated in power transmission networks to improve its operational capability. In addition, some of the energy storage systems such as Battery Energy Storage systems (BESS), Super conducting Magnetic Energy Storage System (SMES) as well large non-conventional energy sources are also increasingly being integrated with the power grid. With large integration of these devices, there is a significant impact on system stability, more importantly on small signal oscillatory instability of the power system.
This thesis primarily focuses on impact of such devices on small signal oscillatory stability of the power systems. More specifically in this thesis small signal stability analysis of a Single Machine Infinite Bus (SMIB) system with a grid connected wind powered Permanent Magnet Synchronous Generator (PMSG) has been presented. A SMIB system has been purposely chosen so that general conclusions can be obtained on the behaviour of the embedded STATCOM/Energy Source (ES) system on system stability. With a better understanding of the impact of such a system it would be probably possible to analyze more complicated multimachine power system and their impact on system stability. Small signal model of the complete system which comprises the generator, transmission network, inter connecting STATCOM, the wind power generator and all associated controllers has been developed. The performances of the system following a small disturbance at various operating conditions have been analyzed.
To obtain quantitative estimates of the damping and synchronizing torques generated in the system, expressions for damping and synchronizing torque clients have been developed.
With these analyses, the relative impact of the STATCOM and STATCOM with ES on system performance have been assessed. It is shown that with active and reactive power modulation capabilities effective and efficient control of small signal oscillations in power systems can be achieved.
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Lee, Chulhan. "Energy efficient transmission in wireless communication networks." 2008. http://hdl.handle.net/2152/17927.
Full textAbstract:
In this dissertation, we study energy efficient transmission in wireless communication networks. The general problem of energy efficient transmission over wireless networks is formulated into optimization problems for the following distinct (but inter-related) settings: Problem Setting 1: The minimization of energy (power) consumption given a system throughput and other constraints, and Problem Setting 2: The maximization of system throughput given energy (power) constraints. Under Problem Setting 1, we focus on energy efficient transmission problems over wideband channels. The first result we obtain is as follows: We consider a two user multiple access channel. In this multiple access channel, previous research shows that cooperation with respect to block error rate is only possible if two transmitters share their sources completely. However, we find that a modified pulse position modulation with synchronization enables cooperation without complete sharing of their sources between two transmitters if we replace a block error rate requirement with a normalized error rate constraint. Normalized error rate, a quantity that resembles bit error rate, is developed in this work as an error metric that is of value in practical communication systems. We show full cooperation between two transmitters without sharing their sources by deriving that the minimum energy per bit required for reliable transmission reduces by quarter compared with the minimum energy per bit required for point-to-point channels. Next, we generalize this analysis to a cognitive communication framework with a wideband cognitive transmitter, which can causally sense signal levels over multiple frequency bands, and a cognitive receiver. We assume that multiple legitimate users already exist in the system and each one transmits in its own non-overlapping frequency band. In this setting, from order statistical analysis, we show that the wideband cognitive transmit-receive pair is able to communicate reliably with minimum energy as if the legitimate users were absent from the system, while causing negligible interference to bandlimited legitimate users. The wideband cognitive transmit-receive pair employs a strategy defined as opportunistic group orthogonal signaling to achieve the minimum energy per bit. Under Problem Setting 2, we investigate the impact of correlation and transmit and receive strategies on the throughput of multiple antenna broadcast channels in cellular networks. With perfect channel state information at the transmitter, it is well known that dirty paper coding (DPC) is the optimal multi-user broadcast transmission method. However, with partial channel state information at the transmitter, the picture changes significantly. Specifically, since multi-user transmission is unable to employ DPC perfectly, singleuser transmission strategies can have a better performance than multi-user transmission strategies when we have a small number of users and correlated antenna gains. We explore the trade-offs between the single-user and multiuser MIMO transmission strategies. Order statistical analysis provides us with both analytical expressions and insights about these trade-offs. We verify that the analytical framework that we develop is accurate by checking the values obtained against numerical results. From this analysis, we confirm that 'mode switching' between single-user and multi-user MIMO transmission schemes is necessary for maximizing throughput for emerging MIMO solutions. Finally, we suggest an adaptive mode switching algorithm between single-user and multi-user MIMO transmission strategies based on this analytical framework.text
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Ramasubbu, Priya. "Sensors and neural networks to supervise integrated renewable energy systems (IRES)." 2008. http://digital.library.okstate.edu/etd/Ramasubbu_okstate_0664M_10069.pdf.
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Sankar, Lalitha. "Relay cooperation in multiaccess networks." 2007. http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.16762.
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Morais, Rodrigo Gonçalves de. "CONGRATS - Convolutional Networks in GPU-based Reliability Assessment of Transmission Systems." Master's thesis, 2021. https://hdl.handle.net/10216/135306.
Full textAbstract:
Monte Carlo Simulation (MCS) is a powerful method frequently used for composite power system adequacy assessment. However it requires a considerable amount of time to provide accurate estimates for the reliability indexes. In the last years, mathematical approaches have been developed, for instance variance reduction techniques, with the aim to speed up this process.
More recently, the MCS method has been implemented in parallel using a Graphics Processing Unit (GPU) to take advantage of the fast calculations
provided by these computing platforms, resulting in reduction of the simulation time.
In this dissertation, a new approach is developed to shrink simulation time by apllying Convolutional Neural Networks (CNN), trained on a GPU.
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Morais, Rodrigo Gonçalves de. "CONGRATS - Convolutional Networks in GPU-based Reliability Assessment of Transmission Systems." Dissertação, 2021. https://hdl.handle.net/10216/135306.
Full textAbstract:
Monte Carlo Simulation (MCS) is a powerful method frequently used for composite power system adequacy assessment. However it requires a considerable amount of time to provide accurate estimates for the reliability indexes. In the last years, mathematical approaches have been developed, for instance variance reduction techniques, with the aim to speed up this process.
More recently, the MCS method has been implemented in parallel using a Graphics Processing Unit (GPU) to take advantage of the fast calculations
provided by these computing platforms, resulting in reduction of the simulation time.
In this dissertation, a new approach is developed to shrink simulation time by apllying Convolutional Neural Networks (CNN), trained on a GPU.
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"Transmission Expansion Planning for Large Power Systems." Doctoral diss., 2013. http://hdl.handle.net/2286/R.I.18820.
Full textAbstract:
abstract: Transmission expansion planning (TEP) is a complex decision making process that requires comprehensive analysis to determine the time, location, and number of electric power transmission facilities that are needed in the future power grid. This dissertation investigates the topic of solving TEP problems for large power systems. The dissertation can be divided into two parts. The first part of this dissertation focuses on developing a more accurate network model for TEP study. First, a mixed-integer linear programming (MILP) based TEP model is proposed for solving multi-stage TEP problems. Compared with previous work, the proposed approach reduces the number of variables and constraints needed and improves the computational efficiency significantly. Second, the AC power flow model is applied to TEP models. Relaxations and reformulations are proposed to make the AC model based TEP problem solvable. Third, a convexified AC network model is proposed for TEP studies with reactive power and off-nominal bus voltage magnitudes included in the model. A MILP-based loss model and its relaxations are also investigated. The second part of this dissertation investigates the uncertainty modeling issues in the TEP problem. A two-stage stochastic TEP model is proposed and decomposition algorithms based on the L-shaped method and progressive hedging (PH) are developed to solve the stochastic model. Results indicate that the stochastic TEP model can give a more accurate estimation of the annual operating cost as compared to the deterministic TEP model which focuses only on the peak load.Dissertation/Thesis
Ph.D. Electrical Engineering 2013
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LANNA, ANDREA. "Control strategies for the integration of renewable energy sources in distribution and transmission networks." Doctoral thesis, 2016. http://hdl.handle.net/11573/875275.
Full textAbstract:
This PhD thesis presents an innovative control strategy for the integration of renewable energy sources in distribution and transmission networks. This work is based on a multilevel control approach that takes into account the current technology, state of the art and legislative limits and considering the most promising trends.
The outer loop control is based on a real time strategy for optimal power flow in presence of storage devices and wind turbine driven by Doubly Fed Induction Generators. These elements work in cooperation defining a dy- namic bus where the generated power is subject to temporal constraints, which establish a coupling between traditional power flow problems related to consecutive time periods; further the uncertainty in wind power genera- tion forecasts requires a continuous update of the planned power profiles, in order to guarantee a dynamic equilibrium among demand and supply. Model predictive control is used for this purpose, considering the dynamic equations of the storage and the wind turbine rotor as prediction models. A proper target function is introduced in order to find a trade-off between the need of minimizing generation costs and the excursions of the storage state of charge and the wind turbine angular speed from reference states. In the case study under consideration storage, wind turbines and a traditional synchronous generator are operated by the Transmission System Operator in the form of a Virtual Power Plant to cover network losses.
The inner loop control is based on a real time control strategy for dy- namically balancing electric demand and supply at local level, in a scenario characterized by a HV/MV substation with the presence of renewable energy sources in the form of photovoltaic generators and an electric energy storage system. The substation is connected to the grid and is powered by an equiv- alent traditional power plant playing the role of the bulk power system. A model predictive control approach is proposed to decide in time the storage setpoint, based on the storage state of charge, the forecast demand and the forecast output of renewable plants.
The two loops allow to obtain an overall control system able to minimize the generation of traditional power systems during the day-ahead market in an hand, and to respect the local load forecasts in other hand thanks the introduction of non-dispatchable renewable energy system and the energy storage ones as well as an innovative predictive control strategy.
Theoretical results are reported on the stability of the proposed control scheme, which is then validated also on a simulation basis. Simulations show the effectiveness of the proposed approach in managing fluctuations of network demand and renewable generation under realistic conditions.This PhD thesis presents an innovative control strategy for the integration of renewable energy sources in distribution and transmission networks. This work is based on a multilevel control approach that takes into account the current technology, state of the art and legislative limits and considering the most promising trends. The outer loop control is based on a real time strategy for optimal power flow in presence of storage devices and wind turbine driven by Doubly Fed Induction Generators. These elements work in cooperation defining a dy- namic bus where the generated power is subject to temporal constraints, which establish a coupling between traditional power flow problems related to consecutive time periods; further the uncertainty in wind power genera- tion forecasts requires a continuous update of the planned power profiles, in order to guarantee a dynamic equilibrium among demand and supply. Model predictive control is used for this purpose, considering the dynamic equations of the storage and the wind turbine rotor as prediction models. A proper target function is introduced in order to find a trade-off between the need of minimizing generation costs and the excursions of the storage state of charge and the wind turbine angular speed from reference states. In the case study under consideration storage, wind turbines and a traditional synchronous generator are operated by the Transmission System Operator in the form of a Virtual Power Plant to cover network losses. The inner loop control is based on a real time control strategy for dy- namically balancing electric demand and supply at local level, in a scenario characterized by a HV/MV substation with the presence of renewable energy sources in the form of photovoltaic generators and an electric energy storage system. The substation is connected to the grid and is powered by an equiv- alent traditional power plant playing the role of the bulk power system. A model predictive control approach is proposed to decide in time the storage setpoint, based on the storage state of charge, the forecast demand and the forecast output of renewable plants. The two loops allow to obtain an overall control system able to minimize the generation of traditional power systems during the day-ahead market in an hand, and to respect the local load forecasts in other hand thanks the introduction of non-dispatchable renewable energy system and the energy storage ones as well as an innovative predictive control strategy. Theoretical results are reported on the stability of the proposed control scheme, which is then validated also on a simulation basis. Simulations show the effectiveness of the proposed approach in managing fluctuations of network demand and renewable generation under realistic conditions.
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Kadrolkar, Abhijit. "Energy Aware Signal Processing and Transmission for System Condition Monitoring." 2010. https://scholarworks.umass.edu/theses/457.
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The operational life of wireless sensor network based distributed sensing systems is limited by the energy provided by a portable battery pack. Owing to the inherently resource constrained nature of wireless sensor networks and nodes, a major research thrust in this field is the search for energy-aware methods of operation. Communication is among the most energy-intensive operations on a wireless device. It is therefore, the focus of our efforts to develop an energy-aware method of communication and to introduce a degree of reconfigurability to ensure autonomous operation of such devices. Given this background, three research tasks have been identified and investigated during the course of this research.
1) Devising an energy-efficient method of communication in a framework of reconfigurable operation: The dependence of the energy consumed during communication on the number of bits transmitted (and received) was identified from prior research work. A novel method of data compression was designed to exploit this dependence. This method uses the time-limited, orthonormal Walsh functions as basis functions for representing signals. The L2 norm of this representation is utilized to further compress the signals. From Parseval’s relation, the square of the L2 norm represents the energy content of a signal. The application of this theorem to our research makes it possible to use the L2 norm as a control knob. The operation of this control knob makes it possible to optimize the number of terms required to represent signals.
The time-limited nature of the Walsh functions was leveraged to inject dynamic behaviour into our coding method. This time-limited nature allows decomposition of finite time-segments, without attendant limitations like loss of resolution that are inherent to derived, discrete transforms like the discrete Fourier transform or the discrete time Fourier transform. This decomposition over successive, finite time-segments, coupled with innovative operation of the previously mentioned control knob on every segment, gives us a dynamic scaling technique. The amount of data to be transmitted is in turn based on the magnitude of the coefficients of decomposition of each time-segment, leading to the realization of a variable word length coding method.
This dynamic coding method can identify evolving changes or events in the quantity being sensed. The coefficients of decomposition represent features present in successive time-segments of signals and therefore enable identification of evolving events. The ability to identify events as they occur enables the algorithm to react to events as they evolve in the system. In other words the data transmission and the associated energy consumption are imparted a reconfigurable, event-driven nature by implementation of the coding algorithm. Performance evaluation of this method via simulations on machine generated (bearing vibration) and biometric (electro-cardio gram) signals shows it be a viable method for energy-aware communication.
2) Developing a framework for reconfigurable triggering: A framework for completely autonomous triggering of the coding method has been developed. This is achieved by estimating correlations of the signal with the representative Walsh functions. The correlation coefficient of a signal segment with a Walsh function gives a picture of the amount of energy localized by the function. This information is used to autonomously tune the abovementioned control knob or, in more proper terms, the degree of thresholding used in compression. Evaluation of this framework on bearing vibration and electro-cardio gram signals has shown results consistent with those of previous simulations.
3) Devising a computationally compact method of feature classification: A method of investigating time series measurements of dynamic systems in order to classify features buried in the signal measurements was investigated. The approach involves discretizing time-series measurements into strings of pre-defined symbols. These strings are transforms of the original time-series measurements and are a representation of the system dynamics. A method of statistically analyzing the symbol strings is presented and its efficacy is studied through representative simulations and experimental investigation of vibration signals recorded from a rolling bearing element. The method is computationally compact because it obviates the need for local signal processing tasks like denoising, detrending and amplification. Results indicate that the method can effectively classify deteriorating machine health, changing operating conditions and evolving defects.
In addition to these major foci, another research task was the design and implementation of a wireless network testbed. This testbed consists of a network of netbooks, connected together wirelessly and was utilized for experimental verification of the variable word length coding method.
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Liu, Ke. "Peak-to-average power ratio reduction in WCDMA systems and cooperative group transmission in sensor networks." 2007. https://scholarworks.umass.edu/dissertations/AAI3289256.
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Wideband code-division multiple-access (WCDMA) is a key technology to satisfy the ever increasing demand for high-speed wireless data. Another critical modern application is that of sensor networks, which consist of a large number of sensors with a limited power supply and computation, and who communicate through a wireless link. In this dissertation, we address technical challenges of each of these. The first two parts of the dissertation consider the high peak-to-average power ratio (PAPR) issue of WCDMA systems, although the results are more generally applicable. High-level clipping is a rare event and hard to simulate. This dissertation analyzes the spectrum of these rare excursions for the complex Gaussian envelope, which is found to have properties that are extensions of the properties of real Gaussian processes. Furthermore, simulation results show that the statistical parameters derived from relatively common events for a low crossing level event can be used to estimate the spectrum in the rare-event high-level case. In addition, time domain PAPR reducing algorithms are simulated and compared. A sensor network consists of a large number of nodes densely distributed across a region. Each sensor has wireless communication capability and some level of intelligence for signal processing and networking of the data. However, a limit power supply and a hostile environment in some cases constrain the data transmission. In this dissertation, we discuss group transmission of correlated information over the physical channel. The power of one node is too limited to reach the collector, but transmitting simultaneously with its neighbors, the effective signal-to-noise (SNR) is increased enough to allow detection. However, this cooperation can cause a reduction in spatial resolution. Our goal is to find the proper tradeoff between the mean squared error (MSE) increase caused by the spatial resolution deterioration and the MSE improvement caused by the SNR enhancement.
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Liu, Hongbo. "Cross-layer design for reliable and efficient data transmission over multiple antenna mobile infostation networks." 2008. http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.17151.
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