Dissertations / Theses on the topic 'Smart grid operation and control'
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Wu, Yu. "System operation and energy management of EV charging stations in smart grid integration applications." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCA030.
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Véhicules électriques (EV) présente les avantages de zéro émission directe et d'un rendement élevé de conversion de l'énergie électrique. Toutefois, les installations de charge des véhicules électriques restent largement rares en raison des coûts d'investissement et d’exploitation élevés. Dans le but d’améliorer le taux de pénétration des installations de charge de véhicules électriques, cette thèse étudie le contrôle du système et l’optimisation de l’activité économique des stations de charge de véhicules électriques (EVCS).Premièrement, en tant que principes de contrôle du système de gestion de l’énergie de niveau supérieur, les techniques de contrôle principales sont étudiées pour le fonctionnement en temps réel d’un système EVCS. Afin de garantir la stabilité et la capacité dynamique du système de micro-réseau de chargement de véhicules électriques, ce travail a porté sur les techniques de contrôle coordonnées d'un système EVCS avec un système photovoltaïque local et un système de stockage.Deuxièmement, afin de réduire les coûts de fonctionnement de l’EVCS, un EMS basé sur la programmation dynamique approximative (ADP) est proposé pour l’EVCS équipé de plusieurs types de chargeurs (EVCS-MTC). Plusieurs véhicules électriques peuvent acquérir le service de charge via un chargeur commun dans l’EVCS-MTC. Dans l'EMS proposé, l'ADP et l'algorithme d'évolution (EA) sont combinés pour déterminer le temps de début de charge optimal pour chaque EV.Enfin, afin d'intégrer les énergies renouvelables dans l'EVCS, une formulation de processus de décision de Markov (MDP) à horizon fini est proposée pour le fonctionnement optimal d'un EVCS assisté par PV sur un campus universitaire, utilisant la technologie de véhicule à réseau (V2G). fournir des services auxiliaires et prendre en compte le prix dynamique de l'électricité et les comportements incertains des propriétaires de EVElectric vehicles (EV) have the advantages of zero direct emissions and high electrical energy conversion efficiency. However, EV charging facilities remain largely scarce due to the high investment and operation costs. In order to improve the penetration rate of EV charging facilities, the system control and economic operation optimization of EV charging stations (EVCS) are studied in this thesis.Firstly, as the control fundamentals of upper-level energy management system (EMS), the primary control techniques are studied for the real-time operation of an EVCS. In order to ensure the stability, dynamic capability of the EV charging micro grid system, this work investigated the coordinated control techniques of an EVCS with a local PV system and ESS.Secondly, in order to reduce the operation costs of the EVCS, an approximate dynamic programming (ADP) based EMS is proposed for the EVCS equipped with multiple types of chargers (EVCS-MTC). Multiple EVs can acquire the charging service through a common charger in the EVCS-MTC. In the proposed EMS, the ADP and the evolution algorithm (EA) are combined to determine the optimal charging start time for each EV.Lastly, in order to integrate the renewable energy into EVCS, a finite-horizon Markov Decision Process (MDP) formulation is proposed for the optimal operation of a PV assisted EVCS in a university campus, employing the vehicle-to-grid (V2G) technology to provide ancillary services and taking dynamic electricity price and uncertain behaviors of EV owners into considerations
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Onen, Ahmet. "Model-Based Grid Modernization Economic Evaluation Framework." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/46981.
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A smart grid cost/benefit analysis answers a series of economic questions that address the incremental benefits of each stage or decision point. Each stage of the economic analysis provides information about the incremental benefits of that stage with respect to the previous stage. With this approach stages that provide little or no economic benefits can be identified. In this study there are series of applications,-including quasi-steady state power flows over time-varying loads and costs of service, Monte Carlo simulations, reconfiguration for restoration, and coordinated control - that are used to evaluate the cost-benefits of a series of smart grid investments.
In the electric power system planning process, engineers seek to identify the most cost-effective means of serving the load within reliability and power quality criteria. In order to accurately assess the cost of a given project, the feeder losses must be calculated. In the past, the feeder losses were estimated based upon the peak load and a calculated load factor for the year. The cost of these losses would then be calculated based upon an expected, fixed per-kWh generation cost. This dissertation presents a more accurate means of calculating the cost of losses, using hourly feeder load information and time-varying electric energy cost data. The work here attempts to quantify the improvement in high accuracy and presents an example where the economic evaluation of a planning project requires the more accurate loss calculation.
Smart grid investments can also affect response to equipment failures where there are two types of responses to consider -blue-sky day and storm. Storm response and power restoration can be very expensive for electric utilities. The deployment of automated switches can benefit the utility by decreasing storm restoration hours. The automated switches also improve system reliably by decreasing customer interruption duration. In this dissertation a Monte Carlo simulation is used to mimic storm equipment failure events, followed by reconfiguration for restoration and power flow evaluations. The Monte Carlo simulation is driven by actual storm statistics taken from 89 different storms, where equipment failure rates are time varying. The customer outage status and durations are examined. Changes in reliability for the system with and without automated switching devices are investigated.
Time varying coordinated control of Conservation Voltage Reduction (CVR) is implemented. The coordinated control runs in the control center and makes use of measurements from throughout the system to determine control settings that move the system toward optimum performance as the load varies. The coordinated control provides set points to local controllers. A major difference between the coordinated control and local control is the set points provided by the coordinated control are time varying. Reduction of energy and losses of coordinated control are compared with local control. Also eliminating low voltage problems with coordinated control are addressed.
An overall economic study is implemented in the final stage of the work. A series of five evaluations of the economic benefits of smart grid automation investments are investigated. Here benefits that can be quantified in terms of dollar savings are considered here referred to as "hard dollar" benefits. Smart Grid investment evaluations to be considered include investments in improved efficiency, more cost effective use of existing system capacity with automated switches, and coordinated control of capacitor banks and voltage regulators. These Smart Grid evaluations are sequentially ordered, resulting in a series of incremental hard dollar benefits. Hard dollar benefits come from improved efficiency, delaying large capital equipment investments, shortened storm restoration times, and reduced customer energy use. The evaluation shows that when time varying loads are considered in the design, investments in automation can improve performance and significantly lower costs resulting in "hard dollar" savings.Ph. D.
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Minh, Hyunsik Eugene. "Communication options for protection and control device in Smart Grid applications." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82401.
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Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science; in conjunction with the Leaders for Global Operations Program at MIT, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 74-75).
Increasing use of electricity, interest in renewable energy sources, and need for a more reliable power grid system are some of the many drivers for the concept of the Smart Grid technology. In order to achieve these goals, one of the critical elements is communication between systems or between the system and human beings. With the decreasing cost of various communication technologies, especially wireless devices and utilities, researchers are increasingly interested in implementing complex two-way communication infrastructures to enhance the quality of the grid. The protection and control relay at the distribution level is one of the key component in enhancing the efficiency, security and reliability of power grid. At present, it may be premature to apply wireless devices to power electronics and to distribution automation, especially for protection and control relays in the distribution level. While fiber technology is still very attractive for protection and control applications in general, wireless technology can bring improvements in user experience applications in the future. The ABB medium voltage group needs to overcome challenges that arise from conservative industry structure, increasing complexity and cost of the product, and needs for higher reliability and security. However, with collaborative efforts among different product groups, the medium voltage group will successfully develop next generation distribution feeder relay.
by Hyunsik Eugene Minh.
S.M.
M.B.A.
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El, Hariri Mohamad. "Secure Control and Operation of Energy Cyber-Physical Systems Through Intelligent Agents." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3854.
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The operation of the smart grid is expected to be heavily reliant on microprocessor-based control. Thus, there is a strong need for interoperability standards to address the heterogeneous nature of the data in the smart grid. In this research, we analyzed in detail the security threats of the Generic Object Oriented Substation Events (GOOSE) and Sampled Measured Values (SMV) protocol mappings of the IEC 61850 data modeling standard, which is the most widely industry-accepted standard for power system automation and control. We found that there is a strong need for security solutions that are capable of defending the grid against cyber-attacks, minimizing the damage in case a cyber-incident occurs, and restoring services within minimal time.
To address these risks, we focused on correlating cyber security algorithms with physical characteristics of the power system by developing intelligent agents that use this knowledge as an important second line of defense in detecting malicious activity. This will complement the cyber security methods, including encryption and authentication. Firstly, we developed a physical-model-checking algorithm, which uses artificial neural networks to identify switching-related attacks on power systems based on load flow characteristics.
Secondly, the feasibility of using neural network forecasters to detect spoofed sampled values was investigated. We showed that although such forecasters have high spoofed-data-detection accuracy, they are prone to the accumulation of forecasting error. In this research, we proposed an algorithm to detect the accumulation of the forecasting error based on lightweight statistical indicators. The effectiveness of the proposed algorithms was experimentally verified on the Smart Grid testbed at FIU. The test results showed that the proposed techniques have a minimal detection latency, in the range of microseconds.
Also, in this research we developed a network-in-the-loop co-simulation platform that seamlessly integrates the components of the smart grid together, especially since they are governed by different regulations and owned by different entities. Power system simulation software, microcontrollers, and a real communication infrastructure were combined together to provide a cohesive smart grid platform. A data-centric communication scheme was selected to provide an interoperability layer between multi-vendor devices, software packages, and to bridge different protocols together.
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Aabakken, Camilla. "Smart Grid Operation & Control : Bruk av uprioritert forbruk for å oppnå optimal drift og en tilfredsstillende forsyningssikkerhet i Midt-Norge." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14198.
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I denne masteroppgaven har det blitt sett på hvordan fleksibilitet i strømforbruk kan utnyttes for å bedre forsyningssikkerheten og redusere topplast. Europa står foran store utfordringer med stadig økende forbruk og økt andel uregulerbar fornybar energi, samtidig som kraftnettet blir eldre. Også i Norge har vi områder med stort energiunderskudd og begrensninger i overføringskapasitet inn til området. Det går utover forsyningssikkerheten, spesielt hvis det oppstår avbrudd og en linje faller ut av drift. Norge skal innføre avanserte måle- og styringssystemer (AMS) med målere som skal registrere forbruket minimum en gang i timen og med mulighet for registrering hvert 15. minutt. Etter forslag fra Olje- og energidepartementet og Norges vassdrags- og energidirektorat skal de nye målerne være installert i alle målepunktene i Norge innen 1.1.2017. I Midt-Norge er det foreslått nye målere i 80 % av målepunktene innen 1.1.2014. Pr. juni 2011 er ikke fristene for utrulling endelig vedtatt. De nye målerne skal gi forbrukerne motivasjon for å redusere forbruket i timer med høy pris og stor belastning på nettet. AMS kan gi mulighet for å koble ut enkelte laster, som varmtvannstanker, panelovner og varmekabler, i husholdninger i et stort område. I denne masteroppgaven fokuseres det på Midt-Norge og hvilken betydning slik utkobling av last kan ha å si for belastningen i sentralnettet. I Midt-Norge er det identifisert en fleksibel last i husholdninger på totalt 240 MW. Det er gjennomført lastflytberegninger der det er sett på virkningen av å koble ut opptil 240 MW last ved feil i en linje i sentralnettet inn til eller i Midt-Norge. Beregningene viser at i situasjoner med høyt forbruk og lav produksjon i Midt-Norge kan lastutkobling benyttes for å holde effektflyten på snittene inn mot området lavere enn overføringsgrensen. Dette er særlig aktuelt ved utfall av en linje inn mot Midt-Norge eller ved tap av produksjon i Midt-Norge. Ved å redusere topplasten kan tapene i sentral- og regionalnettet reduseres med opptil 10 MW, avhengig av hvor mye som kobles ut og last- og produksjon i Midt-Norge den aktuelle timen.
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Bataglioli, Rodrigo Pavanello. "Proteção digital de geradores eólicos com conversores de potência de escala completa no contexto das smart grids." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-25092018-155933/.
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Considerando condições anormais que o Sistema Elétrico de Potência (SEP) está sujeito, a proteção de seus elementos é um tópico importante. Dentre os equipamentos a serem protegidos, destacam-se os geradores devido a representarem elevado custo de investimento e estarem sujeitos a multas por paradas não programadas. Desta forma, com base em pesquisa bibliográfica, observa-se que não existem estudos abrangentes para a proteção individual de máquinas síncronas aplicadas à geração eólica. Além disso, considerando o contexto das smart grids, a presença de baterias e a possibilidade da operação ilhada podem alterar a dinâmica das situações de falta. Portanto, faz-se necessário um estudo do comportamento dos aerogeradores em situações de falha, sabendo que o esquema de proteção depende do tipo de gerador e da maneira como este está conectado ao SEP. Neste sentido, esta pesquisa propôs incluir uma bateria para operar com um gerador eólico de velocidade variável de forma complementar, suavizando a potência de saída e tornando o sistema de conversão de energia eólica forte o suficiente para operar no modo ilhado. A metodologia estabelece vários tipos de falhas para investigar o comportamento da turbina eólica em tais condições. Para realizar as simulações de falta, foi utilizado um simulador digital de tempo real (RTDS®). Com base nisso, um esquema composto por funções de proteção convencionais foi especificado e testado usando o software MATLAB®. Além disso, simulações em laço fechado foram realizadas com relés comercial e universal. Os resultados obtidos com o esquema proposto são bastante promissores.Considering abnormal conditions to which the Electric Power System (EPS) may be subjected, the protection of its elements is an important topic. Among the equipments to be protected, the generators are highlighted, because they represent a high investment cost and are subjected to penalties for unscheduled stoppages. Hence, based on literature, it is observed that there are no comprehensive studies and standards for individual protection of Synchronous Generators (SGs) applied to Wind Energy Conversion System (WECS). Furthermore, considering the smart grids context, the presence of batteries and the possibility of island operation may change the dynamic of fault situations. Therefore, it is necessary to study and analyse the behavior of wind turbines in fault situations, knowing that the protection scheme is dependent on the generator type and the way it is connected to the EPS. In order to study these issues, this research proposed to include a battery to operate with a full-variable speed wind generator in a complementary way, smoothing the output power and making the WECS strong enough to operate in the island mode. The methodology establishes several fault types to investigate the wind turbine behavior in such conditions. In order to conduct the fault simulations, a real time digital simulator (RTDS®) was used. Based on this, a scheme composed by conventional protection functions were specified and tested using the MATLAB® software. Furthermore, hardware-in-the-loop simulations were performed with commercial and universal relays. Very good results in favor of the proposed scheme are presented.
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Leppin, Lorenz. "Development of Operational Strategies for a Heating Pump System with Photovoltaic, Electrical and Thermal Storage." Thesis, Högskolan Dalarna, Energiteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:du-27304.
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This study describes the development of operational strategies for an exhaust air heat pump system that supplies space heating and domestic hot water. The system combines photovoltaic power production with two different storage types. These are electrical storage using batteries and thermal storage in using a domestic hot water tank and in form of the thermal capacity of the building. The investigation of the control strategies is carried out for a detailed single family house model in Sweden in the simulation software TRNSYS. The overall aim of the control strategies is to improve the performance of the energy system in terms of self-consumption, self-sufficiency, final energy and seasonal performance factor. Three algorithms are developed and compared to a base case without additional control. The first algorithm only uses the thermal storage in the hot water tank and the building. The second uses only the battery to store the photovoltaic electricity. The third control algorithm combines both storage types, electrical and thermal. The simulation results show that for the studied system the energetic improvement is higher with the use of electrical storage compared to using thermal storage. The biggest improvement however is reached with the third algorithm, using both storage types in combination. For the case of a photovoltaic-system with 9 kW and battery store with 10.8 kWh and a 180 l hot water store the self-consumption reaches up to 51% with a solar fraction of 41 %. The reduction in final energy consumption for this case is 3057 kWh (31 %) with the heat pump having a seasonal performance factor of 2.6. The highest self-consumption is reached with a photovoltaic-system of 3 kW and battery store with 3.6 kWh, which comes to 71 %.
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de, Paola Antonio. "Distributed control in the smart grid." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/43846.
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This thesis addresses some of the challenges that arise when the new smart grid paradigm is applied to power systems. In particular, novel control strategies are designed to deal in a decentralized matter with the increasing complexity of the network. Two main areas are investigated: participation to frequency control of variable-speed wind turbines and management of large populations of competing agents (e.g. micro-storage devices and "smart appliances") that exchange energy with the system. The first part of this work presents two different techniques that allow wind turbines to provide frequency response: following the trip of a large power plant, the turbines population increases its aggregate generated power, reducing the resulting drop in frequency. A first method models the wind turbines as stochastic hybrid systems: the generators switch randomly between two operative modes characterized by different efficiency and generated power at equilibrium. Transitions are driven by frequency-dependent switching functions: single generators behave randomly while large populations perform deterministically, changing the total power in response to frequency variations. The second proposed control strategy allows a prescribed increase in generation, distributing the control effort among the individual turbines in order to maximize the duration of frequency support or minimize the resulting kinetic energy losses. The second part of the thesis deals with large populations of agents which determine their operation strategy in response to a broadcast price signal. Micro-storage devices performing energy arbitrage are initially considered: each agent charges/discharges during the day in order to maximize its profit. By approximating the number of devices as infinite, modelling the population as a continuum and describing the problem through a differential game with infinite players (mean field game), it is possible to avoid synchronicity phenomena and determine an equilibrium for the market. Finally, the similar case of flexible demand is analyzed, with price-responsive appliances that schedule their power consumption in order to minimize their energy cost. Necessary and sufficient conditions for the existence of a Nash equilibrium are provided, extending the results by introducing time-varying constraints on the power rate and considering partial flexibility of the devices.
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Asbery, Christopher W. "SMART GRID COMMUNICATIONS." UKnowledge, 2012. http://uknowledge.uky.edu/ece_etds/10.
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Smart grid technologies are starting to be the future of electric power systems. These systems are giving the utilities detailed information about their systems in real time. One of the most challenging things of implementing smart grid applications is employing the communications into the systems. Understanding the available communications can help ease the transition to these smart grid applications. Many of the utility personnel are spending too much time trying to figure out which communication is better for their application or applications. So this thesis presents the different communication types available with discussing the different attributes in which these communication types are going to offer to the utility. Then these communication types are looked such that utilities can quickly understand how to approach the difficult task of obtaining the information from the different smart grid applications by the use of different communication options.
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Sabillón, Antúnez Carlos Francisco. "Mathematical optimization of unbalanced networks operation with smart grid devices." Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/154075.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
As redes de distribuição de energia elétrica devem estar preparadas para fornecer um serviço econômico e confiável a todos os clientes, bem como para integrar tecnologias relacionadas à geração distribuída, armazenamento de energia e veículos elétricos. Uma representação adequada da operação das redes de distribuição, considerando as tecnologias de redes inteligentes, é fundamental para atingir esses objetivos. Este trabalho apresenta formulações matemáticas para a operação em regime permanente das redes de distribuição, que consideram o desequilíbrio de redes trifásicas. Modelos matemáticos da operação de dispositivos relacionados à redes inteligentes presentes em redes de distribuição são desenvolvidos (e.g., dispositivos de controle volt-var, sistemas de armazenamento de energia e veículos elétricos). Além disso, características relacionadas à dependência da tensão das cargas, geração distribuída e limites térmico e de tensão também estão incluídos. Essas formulações constituem um marco matemático para a análise de otimização da operação das redes de distribuição de energia elétrica, o que possibilita modelar os processos de tomada de decisões. Objetivos diferentes relacionados a aspectos técnicos e/ou econômicos podem ser almejados dentro deste marco; Além disso, a extensão para otimização multi-período e multi-cenário é discutida. Os modelos apresentados são construídos com base em formulações de programação linear inteira mista, evitando o uso de formulações não-lineares inteiras mistas convencionais. A aplicação do marco apresentado é ilustrada em abordagens de controle para coordenação de carregamento de veículos elétricos, controle de magnitude de tensão e controle de geração distribuída renovável. Diversos métodos são desenvolvidos, com base no marco de otimização matemática, para otimizar a operação de sistemas de distribuição desbalanceados, considerando não apenas diferentes penetrações de veículos elétricos e fontes de energia renováveis, mas também a presença de sistemas de armazenamento e dispositivos de controle volt-var. A este respeito, o agendamento dinâmico e a otimização multi-período de janela rolante são frequentemente usados para alcançar uma operação ótima na rede. A eficácia e robustez das metodologias, bem como a confiabilidade do marco de otimização matemática, são verificados usando vários sistemas de teste (e.g., 123-node, 34-node e 178-node) com nós de média e baixa tensão, diferentes janelas de controle e várias disponibilidades de controle relacionadas aos dispositivos de rede inteligente.
Electric distribution networks should be prepared to provide an economic and reliable service to all customers, as well as to integrate technologies related to distributed generation, energy storage, and plug-in electric vehicles. A proper representation of the electric distribution network operation, taking into account smart grid technologies, is key to accomplish these goals. This work presents mathematical formulations for the steady-state operation of electric distribution networks, which consider the unbalance of three-phase grids. Mathematical models of the operation of smart grid-related devices present in electric distribution networks are developed (e.g., volt-var control devices, energy storage systems, and plug-in electric vehicles). Furthermore, features related to the voltage dependency of loads, distributed generation, and voltage and thermal limits are also included. These formulations constitute a mathematical framework for optimization analysis of the electric distribution network operation, which could assist planners in decision-making processes. Different objectives related to technical and/or economic aspects can be pursued within the framework; in addition, the extension to multi-period and multi-scenario optimization is discussed. The presented models are built based on mixed integer linear programming formulations, avoiding the use of conventional mixed integer nonlinear formulations. The application of the presented framework is illustrated throughout control approaches for plug-in electric vehicle charging coordination, voltage magnitude control, and renewable distributed generation control. Several methods are developed, based on this framework, to optimize the operation of unbalanced distribution systems considering not only different penetrations of electric vehicles and renewable energy sources but also the presence of storage systems and volt-var control devices. In this regard, dynamic scheduling and rolling multi-period optimization are often used to achieve optimal economic operation in the grid. The effective and robustness of the methodologies, as well as the reliability of the mathematical framework, are verified using many test systems (e.g., 123-node, 34-node, and 178-node) with medium and low voltage nodes, different operation control time frames, and several control availabilities related to the smart grid devices.
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Vuković, Ognjen. "Cyber-security in Smart Grid Communication and Control." Doctoral thesis, KTH, Kommunikationsnät, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-152223.
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Society is increasingly dependent on the reliable operation of power systems. Power systems, at the same time, heavily rely on information technologies to achieve efficient and reliable operation. Recent initiatives to upgrade power systems into smart grids target an even tighter integration with information technologies to enable the integration of renewable energy sources, local and bulk generation and demand response. Thus for the reliable operation of smart grids, it is essential that its information infrastructure is secure and reliable in the face of both failures and attacks. This thesis contributes to improving the security of power systems against attacks on their information infrastructures. The contributions lie in three areas: data integrity, data condentiality, and data availability of power system applications. We analyze how characteristics of power system applications can be leveraged for detection and mitigation of data integrity attacks. We consider singleand multi-area power system state estimation. For single-area state estimation, we look at the integrity of measurement data delivered over a wide area communication network. We deffine security metrics that quantify the importance of particular components of the communication network, and that allow us to optimize the deployment of network, transport and application layer security solutions. For multi-area state estimation, we look at the integrity of data exchanged between the control centers of neighboring areas in face of a targeted trojan that compromises an endpoint of the secure communication tunnel. We deffine multiple attack strategies and show that they can signifficantly disturb the state estimation. Moreover, we propose schemes that could be used for detection, localization, and mitigation of data integrity attacks. We investigate how to provide data confidentiality for power system applications when they utilize cloud computing. We focus on contingency analysis and propose an approach to obfuscate information regarding power flows and the presence of a contingency violation while allowing the operator to analyze contingencies with the needed accuracy in the cloud. Our empirical evaluation shows that the errors introduced into power flows due to the proposed obfuscation are small, and that the RMS errors introduced grow linearly with the magnitude of obfuscation. We study how to improve data availability in face of gray hole attacks combined with traffic analysis. We consider two cases: SCADA substation to control center communication using DNP3, and inter-control center communication. In the first case, we propose a support vector machine-based traffic analysis algorithm that uses only the information on timing and direction of three consecutive messages, and show that a gray hole attack can be effectively performed even if the traffic is sent through an encrypted tunnel. We discuss possible mitigation schemes, and show that a minor modication of message timing could help mitigate the attack. In the second case, we study how anonymity networks can be used to improve availability at the price of increased communication overhead and delay. We show that surprisingly availability is not always improved with more overhead and delay. Moreover, we show that it is better to overestimate than to underestimate the attacker's capabilities when conguring anonymity networks.QC 20140924
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Paulus, Amanda. "A Model-Predictive-Control Based Smart-Grid Aggregator." Thesis, KTH, Optimeringslära och systemteori, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-230958.
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Intermittent energy source usage, such as solar and wind power, is continuously increasing. Intermittent energy sources are highly dependent on prevailing weather conditions, resulting in stochastic electricity generation. The expected stochasticity in electricity generation will cause issues for the current power grid. Moreover, an expected issue for the Swedish power grid is higher peak loads. Thus, there is an emerging need for novel and smart power systems capable of shifting peak loads in the future electricity grid. Model Predictive Control (MPC) is a sophisticated control method that is suitable for smart-grid aggregators. Hence, MPC can be used to optimally control the efficiency of energy use in a smart grid and shift peak loads. The purpose of this thesis is to investigate optimal peak load-shifting and efficiency of electrical substation operation in a smart grid in Ramsjöåsen, Sweden, using an MPC based smart-grid aggregator. Furthermore, the purpose is also to contribute to the theoretical foundation for future peak load-shifting in smart grids. Within the thesis project a mathematical model for the smart grid in Ramsjöåsen is developed, which is then used to simulate different scenarios. The simulated results indicate that an MPC based smart-grid aggregator improves the performance of the smart grid in Ramsjöåsen, as regards to both peak load-shifting and efficiency of electrical substation operation.Användningen av intermittenta energikällor, såsom sol och vindkraft, ökar ständigt. Intermittenta energikällor är starkt beroende av rådande väderförhållanden, vilket resulterar i stokastisk elproduktion. Den förväntade stokasticiteten i elproduktion kommer att orsaka problem för det nuvarande elnätet. Dessutom förväntas högre toppbelastningar för det svenska elnätet. Således finns ett växande behov av nya och smarta kraftsystem som kan reducera toppbelastningar i det framtida elnätet. Model Predictive Control (MPC) är en sofistikerad styrningsmetod som är lämplig för smart-näts aggregatorer. Därav kan MPC användas för att optimalt styra effektivitet av energianvändning i ett smart nät och minska toppbelastningar. Syftet med detta examensarbete är att undersöka optimal reducering av toppbelastningar och drift-effektivitet av transformatorstationen i ett smart nät i Ramsjöåsen, Sverige, med hjälp av en MPC baserad smart-näts aggregator. Dessutom är syftet att bidra till den teoretiska grunden för framtida topplastskapning i smarta nät. Inom examensarbetsprojektet utvecklas en matematisk modell för smart nätet i Ramsjöåsen, som sedan används för att simulera olika scenarier. De simulerade resultaten indikerar att en MPC baserad smart-näts aggregator förbättrar smart nätets prestanda i Ramsjöåsen, vad gäller både topplastsreducering och drifteffektivitet av transformatorstationen.
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Cavraro, Guido. "Modeling, Control and Identification of a Smart Grid." Doctoral thesis, Università degli studi di Padova, 2015. http://hdl.handle.net/11577/3424251.
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We are in front of an epochal change in the power distribution and generation scenario. The increasing request of energy, the energy dependency of several countries from few foreign nations endowed with oilfield or gas field, and, on the other hand, the climate change and environmental issues are the main explanation of the recent development and spread of renewable distributed energy generation technologies. Examples of them
are photovoltaic panels, wind turbines or geothermal, biomass, or hydroelectric. They are called small-size generators, or micro-generator, since the amount of power they can produce is significantly lower than the one produced by the huge, classical power plants. These distributed energy resources (DERs) are located close to where electricity is used, in the distribution network. Furthermore, they are connected to the electrical grid via electronic interfaces, the inverters, that could allow us to control the power injected into the grid. This thesis is focused on the study of some crucial aspects of this new energetic
scenario:
1. Modeling: we recall the classical models and a recent linearized one of the power systems, that will be very useful for the design and the analysis of our algorithms.
2. Optimal Reactive Power Flow (OPRF) problem: in this part we recall classical and recent algorithms that deal with the reactive power regulation. In particular, we focus on the ones that solve the OPRF problem, i.e. the problem of the amount of reactive power to be injected by each micro-generators, in order
to achieve “optimal” performance. We choose, as an optimality achievement, the minimization of the line losses. Finally we derive and propose our OPRF algorithm, providing formal proves of its convergence to the optimal solution.
3. Optimal Power Flow (OPF) problem: the OPF problem’s aim is to find an operating point of the power system that optimize a cost function (tipically the generation cost) satisfying the power demand and some operative constraints. After recalling the most popular algorithms that solve the OPF problem, we propose two
of them. In this framework there are mainly two possible scenarios. The first is related to the “utility point of view”, where the total cost accounts for the production cost of the energy (that comes from big generation plants such as nuclear or hydro-electrical plants) and for the remuneration to be paid to the owners of DERs. In this framework, the utility imposes a behavior procedure to be followed by the producers to compute the amount of energy they have to inject into the grid to minimize the total cost. The first algorithm deal with this scenario. The second one is related to the “producer point of view”. Since the owners of the DERs are paid proportionally to the energy that they inject, they would like to
maximize the power they inject, while keeping satisfied some operative constraints. The result is a game among the agents. A first treatment on this scenario is given by the second algorithm.
4. Switches monitoring for topology identification: in this part, after a literature review, we propose a algorithm for the identification of switches actions. They modify the topology of the electrical grid, whose knowledge is fundamental for monitoring, control and estimation. This algorithm works analyzing how the phasorial voltage profile vary and recognize a kind of signature left by the switches status change.Stiamo vivendo un cambiamento epocale dello scenario di produzione e distribuzione dell’energia. L’incremento della richiesta di energia, il fatto che molte Paesi dipendano energeticamente da poche nazioni ricche di giacimenti di gas o petroliferi e, inoltre, il cambiamento climatico e l’inquinamento costituiscono la ragione principale del recente sviluppo e diffusione di tecnologie per la generazione di energia da fonte rinnovabili. Alcuni esempi ne sono i pannelli fotovoltaici oppure generatori eolici, geotermici, idroelettrico o dalle biomasse. Essi sono generatori di piccole dimensione, o micro-generatori, visto che le loro dimensioni e la quantità di energia che producono sono decisamente inferiori a quelle dei grandi, classici impianti di generazioni. Queste fonti distribuite di energia (DERs) si trovano vicino agli utilizzatori, nella rete di distribuzione. Inoltre, essi sono collegati alla rete attraverso interfacce elettroniche, gli inverter, che ci potrebbero permettere di controllare la quantità di potenza che essi iniettano. Questa tesi si concentra sullo studio di alcuni aspetti cruciali di di questo nuovo scenario energtico, e è composta da quattro parti principali, ciascuna delle quali tratta un aspetto diverso. Esse sono: 1. Modellistica: qui si richiamano i modelli classici e un recente modello linearizzato, che sarà utile per la progettazione e l’analisi degli algoritmi proposti, dei sistemi di potenza. 2. Ottimizzazione dei flussi di potenza reattiva: in questa parte si richiamano i classici e i più recenti algoritmi di gestione della potenza reattiva. In particolare ci si concentra su quelli che ne ottimizzano i flussi, cioè che si focalizzano sul problema di decidere quanta potenza reattiva ciascun micro-generatore deve iniettare se si vogliono ottenere delle prestazioni “ottime”. Come indice di ottimalità è stata scelta la miniizzazione delle perdite sulle linee. Infine viene progettato e analizzato il nostro algoritmo di ottimizzazione, fornendo dimostrazione formale della sua convergenza. 3. Ottimizzazione dei flussi di potenza: lo scopo di questo problema è quello di trovare una configurazione che ottimizza una funzione costo (di solito il costo di generazione) e che soddisfa alcuni vincoli operativi. Dopo aver richiamato i più famosi algoritmi che risolvono questo problema, ne vengono proposti due. Questo perchè vi sono principalmente due scenari. Il primo è connesso al punto di “vista dell’utility”, dove il costo tiene conto sia dell’effettivo costo di generazione dell’energia (che arriva dai grandi impianti di generazione, quali centrali nucleari o idroelettriche) e della remunerazione che deve essere data ai proprietari delle DERs per l’energia che producono. In questo caso , l’utility impone una procedura per calcolare la potenza da iniettare per minimizzare il costo totale. Il primo algoritmo rientra in questo scenario. Il secondo è connesso al punto di “vista del proprietario di DERs”. Poichè questi viene pagato proporzionalmente alla quantità di energia che inietta, vorrebbe massimizzare la potenza che inietta, soddisfando comunque alcuni vincoli operativi. Ne viene fuori un conflitto fra i diversi proprietari. Una trattazione di questo scenario è data dal secondo algoritmo. 4. Controllo degli interruttori per l’identificazione della topologia: in questa parte, dopo una revisione della letteratura, viene proposto un algoritmo per l’identificazione delle azioni degli interruttori nella rete. Queste modificano la topologia della rete elettrica, la cui conoscenza è fondamentale per il controllo, la supervisione e la stima. Questo algoritmo analizza le variazioni dei profili delle tensioni fasoriali e cerca di riconoscere in esse una sorta di firma della particolare azione degli interruttori.
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Daniela, Rosić. "Model kontrole pristupa u Smart Grid sistemima." Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2017. https://www.cris.uns.ac.rs/record.jsf?recordId=104820&source=NDLTD&language=en.
Full textAbstract:
U tezi je analiziran problem kontrole pristupa u Smart Grid sistemima. Formalno je specificiran model kontrole pristupa za Smart Grid koji je zasnovan na unapređenju i proširenju RBAC modela i koji je usklađen sa aktuelnim zahtevima u elektroenergetskoj industriji. Postavljena je softverska arhitektura predloženog modela kontrole pristupa, čija je prototipska implementacija zatim integrisana u simuliranom Smart Grid okruženju.This thesis discusses the challenges related to access control in SmartGrid systems. A formal model for access control in the Smart Grid isspecified, extending the role-based access control (RBAC) model to bein accordance with the existing security requirement in the power industry.Based on the proposed access control model, software architecture wasdeveloped and its prototype implementation is integrated in a Smart Gridsimulated environment.
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Zou, Zhixiang [Verfasser]. "Control of Smart Transformer-fed Distribution Grid / Zhixiang Zou." Kiel : Universitätsbibliothek Kiel, 2019. http://d-nb.info/1196090998/34.
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Restrepo, Juan Diego Echeverry. "Otimização em tempo real para o controle Volt/VAr em sistemas de distribuição de energia elétrica." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-22092016-104547/.
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Atualmente, as concessionárias de energia enfrentam vários desafios na tentativa de fornecer energia com qualidade e confiabilidade, por exemplo, redes de distribuição com pouco monitoramento e controle, envelhecimento dos ativos, atender a crescente demanda dos consumidores e satisfazer padrões de qualidade, entre outros. No Brasil, para atingir os índices de qualidade no fornecimento de energia estabelecidos pela Agência Nacional de Energia Elétrica (ANEEL), tem-se como alternativa aumentar a inteligência da rede com sistemas de tecnologia de informação (TI), além de utilizar Dispositivos Eletrônicos Inteligentes (IEDs), medidores inteligentes e sensores. Adicionalmente é necessário o emprego de uma infraestrutura de comunicação que forneça uma visibilidade abrangente das condições de carga e do estado do sistema de distribuição, permitindo fazer uso de técnicas de otimização e tomada de decisão para aumento da inteligência. O controle da tensão e o gerenciamento da potência reativa (Volt/VAr) são práticas de automação que podem ser empregadas nos sistemas de distribuição. Estas práticas ajudam a aumentar o benefício, a confiabilidade e a eficiência no fornecimento da qualidade do produto, minimizando os custos de operação e manutenção nas concessionárias. Na presente dissertação foi desenvolvida uma metodologia de controle Volt/VAr descentralizado (subestação), por meio da coordenação e controle dos transformadores com mudança de tap sob carga - LTC, dos bancos de capacitores localizados na subestação e ao longo dos alimentadores, bem como dos reguladores de tensão instalados ao longo dos alimentadores. Destaca-se a utilização da técnica de Estimação de Estados, a qual possibilita o uso da metodologia de controle Volt/VAr em tempo real. O algoritmo de otimização desenvolvido neste trabalho foi implementado através de simulações numa rede teste e numa rede real que permitem mostrar o potencial da formulação matemática desenvolvida. Os resultados da metodologia proposta comprovam a melhoria do perfil de tensão dos alimentadores da rede testada ao longo do dia, assim como uma diminuição das perdas técnicas, as quais chegaram a diminuir 7% em energia. Estes resultados foram alcançados sem ultrapassar a quantidade de operações definidas por dia nos diferentes dispositivos de controle.Currently, power utilities face challenges in order to provide energy considering minimum requirements of power quality and reliability due to the absence of control and monitoring infrastructure, aging assets, growing demand, amongst others. In Brazil, the Agência Nacional de Energia Elétrica (ANEEL) establishes specific power quality and reliability indices. Power utilities should attend the limits for those indices by improving intelligence of network using IT systems, installing Intelligent Electric Devices (IEDs), smart meters and sensors, amongst others. Additionally, communication infrastructure is needed to provide the monitoring of load conditions and distribution system state. Optimization and decision-making tools are important for developing smart grids. Voltage control and reactive power management (Volt/VAr) are automation techniques that can be used in distribution systems. These practices lead to benefits for the utilities such as improvement of reliability and efficiency of the system, minimization of operation and maintenance costs, amongst others. In the present dissertation a methodology for decentralized control (Volt/VAr) was developed, through the coordination and control of load tap changers (LTCs) in power transformers and capacitors banks located at the substation, as well as capacitor banks and voltage regulators scattered throughout the feeders. State Estimation was utilized, which allows the application of the Volt/VAr Control methodology in real time environment. The optimization algorithm developed in this work was implemented through simulations in a test network and in a real network which validated the proposed methodology showing the potentiality of the mathematical model. The results of the proposed method showed voltage profile improvement over the day for the network tested as well as a 7% decrease in power energy losses. These results were achieved without exceeding the number of operations per day defined for all control devices.
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Alfares, Abdulgafor Mohammed. "Analysis of power converter's control techniques in Grid-Tie and AC Micro/Smart Grid." Thesis, Marquette University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1553890.
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Power converters have an outstanding potential in micro and smart grid applications that require flexible and fast power control as well as rigid voltage regulation at the point of common coupling. Power converters are required to properly operate under several modes of operation such as grid-tie and micro-grid modes of operations. In addition, the control system should be designed to enable proper load sharing between several units.
Several control techniques have been proposed in the literature to address most of the control requirements of the power converters under different operating modes mentioned above. However, references found in the literatures are usually centered on the analysis of the system under only one mode of operation and using a single control strategy. Comprehensive study that combines an in depth analysis of the power converters control under several modes are very scarce in the literature.
In this thesis, a detailed survey and analysis of power converter control techniques in Grid-Tie and AC Micro/Smart Grid applications are introduced. This analysis is based on detailed nonlinear time domain simulations as well as average and small signal models for system stability assessment and performance evaluation.
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Wang, Yuchang. "Decision-making techniques for smart grid energy management." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/28970.
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This thesis has contributed to the design of suitable decision-making techniques for energy management in the smart grid with emphasis on energy efficiency and uncertainty analysis in two smart grid applications. First, an energy trading model among distributed microgrids (MG) is investigated, aiming to improve energy efficiency by forming coalitions to allow local power transfer within each coalition. Then, a more specific scenario is considered that is how to optimally schedule Electric Vehicles (EV) charging in a MG-like charging station, aiming to match as many as EV charging requirements with the uncertain solar energy generation. The solutions proposed in this thesis can give optimal coalition formation patterns for reduced power losses and achieve optimal performance for the charging station. First, several algorithms based on game theory are investigated for the coalition formation of distributed MGs to alleviate the power losses dissipated on the cables due to power transfer. The seller and buyer MGs can make distributed decisions whether to form a coalition with others for energy trading. The simulation results show that game theory based methods that enable cooperation yield a better performance in terms of lower power losses than a non-cooperative approach. This is because by forming local coalitions, power is transferred within a shorter distance and at a lower voltage. Thus, the power losses dissipated on the transmission lines and caused by power conversion at the transformer are both reduced. However, the merge-and-split based cooperative games have an inherent high computational complexity for a large number of players. Then, an efficient framework is established for the power loss minimization problem as a college admissions game that has a much lower computational complexity than the merge-and-split based cooperative games. The seller and buyer MGs take the role of colleges and students in turn and apply for a place in the opposite set following their preference lists and the college MGs’ energy quotas. The simulation results show that the proposed framework demonstrates a comparable power losses reduction to the merge-and-split based algorithms, but runs 700 and 18000 times faster for a network of 10 MGs and 20 MGs, respectively. Finally, the problem of EV charging using various energy sources is studied along with their impact on the charging station’s performance. A multiplier k is introduced to measure the effect of solar prediction uncertainty on the decision-making process of the station. A composite performance index (the Figure of Merit, FoM) is also developed to measure the charging station’s utility, EV users charging requirements and the penalties for turning away new arrivals and for missing charging deadlines. A two-stage admission and scheduling mechanism is further proposed to find the optimal trade-off between accepting EVs and missing charging deadlines by determining the best value of the parameter k under various energy supply scenarios. The numerical evaluations give the solution to the optimization problem and show that some of the key factors such as shorter and longer deadline urgencies of EVs charging requirements, stronger uncertainty of the prediction error, storage capacity and its initial state will not affect significantly the optimal value of the parameter k.
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Massa, Giovanni. "Integrazione delle Fonti Rinnovabili nelle SMART-GRID." Doctoral thesis, Universita degli studi di Salerno, 2013. http://hdl.handle.net/10556/1514.
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2011 - 2012Energy market liberalization processes and incentive programs by various National governmwnts are driving an increasing diffusion of a wide variety of Distributed Generation (DG) powe plants, causing huge changes and challenges in Electrical Power Systems (EPS). in fact, while in the past the power generation was mainly concentrated in a small number of large power plants directly connected to the high voltage Transmission Networks (TNs), DG units can be connected directly to Disribution Networks (DNs), causing both DNs planning and management issues. Thus, innovative planning and management approaches of these new active networks are necessary to ensure the best integration of Distributed Energy Resources (DERs) within EPSs as well as TNs and DNs optimal use. The thesis work addresses these aspects by investigating DERs integration issues and their impact on voltage profiles within DNs. The work proposes a technique for DERs decentralized control at the Point of Commom Coupling (PCC) with the DN, designed to contain voltage variations within regulatory limits and to maximize active power delivery to the grid... [edited by Author]
La sempre maggior diffusione dei sistemi di generazione distribuita, anche di dimensioni medio-piccole, legata da un lato ai processi di liberalizzazione dei mercati dell’energia e dall’altro alle incentivazioni all’impiego di fonti rinnovabili promosse da vari Paesi, sta profondamente modificando la struttura del sistema elettrico. Infatti, mentre in passato la generazione era principalmente concentrata in un numero ristretto di centrali di grandi dimensioni direttamente connesse alle reti di trasporto in alta e altissima tensione, la generazione distribuita può avvenire anche in corrispondenza dello stesso utente finale direttamente sulla rete di distribuzione, con problemi tanto di pianificazione che di gestione dell’intera rete elettrica. Si rendono, pertanto, necessari nuovi approcci per la pianificazione e la gestione delle reti di distribuzione attive, atti a garantire la migliore integrazione possibile di tali risorse, sia in termini di massima producibilità degli impianti di generazione e sia di impiego ottimo delle reti di trasmissione e distribuzione. Di tali aspetti si occupa il presente lavoro di tesi, investigando le problematiche connesse all’integrazione dei sistemi di generazione distribuita all’interno delle reti elettriche di distribuzione e al loro impatto sui profili di tensione, proponendo una tecnica di controllo decentralizzato dei punti di connessione tra i generatori e la rete finalizzata al contenimento delle variazioni di tensione e alla massimizzazione dell’energia immessa in rete... [a cura dell'Autore]
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Wang, Lu. "Optimization and control of energy storage in a smart grid." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/412630/.
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Environmental issues such as global warming, limited storage of fossil fuels and concerns about cost and energy efficiency are driving the development of the future smart grid. To reduce carbon emissions, it is expected that there will be a large-scale increase in the penetration of renewable generators (RGs), electric vehicles (EVs) and electrical heating systems. This will require new control approaches to ensure the balance of generation and consumption and the stability of the power grid. Energy storage can be used to support grid operations by controlling frequency and voltage, and alleviating thermal overload. This thesis makes three novel contributions to the field: optimal battery sizing; optimal dispatch of vehicle-to-grid batteries; and optimal coordination of EV batteries and RGs. Appropriate sizing of the energy storage is very important when using it to support the power system. In this thesis, an approach has been proposed to determine the capacity of a battery storage providing support during N-1 contingencies to relieve transmission line thermal overload. In addition, as the increasing use of EV is an inevitable trend in the future smart grid, the system's peak demand may increase significantly due to EV charging, causing serious overloading of some power system facilities such as transformers and cables in the grid if an effective EV battery dispatch strategy is not used. Therefore, this report presents a dispatch strategy for EV batteries based on the Analytic Hierarchy Process taking into account both vehicle users' and power system requirements and priorities, as well as the constraints of the battery system. However, using renewable power to charge EVs is the prerequisite of realizing clean transport. EVs can store the extra renewable power and feed it into the grid when needed via vehicle-to-grid operations to increase the utilization and integration of RGs in the power grid. Thus, the optimal dispatch of EVs and RGs to realize the synergy between them will be one of the key challenges. Two optimal agent-based coordinated dispatch strategies are developed in this thesis, respectively using dynamic programming and the A* search procedure (comparisons between these two algorithms are made and discussed), for the synergistic integration of EVs and RGs, so that the benefits of both EV users and power grid are maximized. Each of the proposed approaches was tested on an IEEE Reliability Test System or a modified UK generic distribution system (UKGDS) using MATLAB. The simulation results demonstrate the feasibility and efficacy of the proposed approaches.
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Tazay, Ahmad F. "Smart Inverter Control and Operation for Distributed Energy Resources." Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/7097.
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The motivation of this research is to carry out the control and operation of smart inverters and voltage source converters (VSC) for distributed energy resources (DERs) such as photovoltaic (PV), battery, and plug-in hybrid electric vehicles (PHEV). The main contribution of the research includes solving a couple of issues for smart grids by controlling and implementing multifunctions of VSC and smart inverter as well as improving the operational scheme of the microgrid. The work is mainly focused on controlling and operating of smart inverter since it promises a new technology for the future microgrid. Two major applications of the smart inverter will be investigated in this work based on the connection modes: microgrid at grid-tied mode and autonomous mode.
\indent In grid-tied connection, the smart inverter and VSC are used to integrate DER such as Photovoltaic (PV) and battery to provide suitable power to the system by controlling the supplied real and reactive power. The role of a smart inverter at autonomous mode includes supplying a sufficient voltage and frequency, mitigate abnormal condition of the load as well as equally sharing the total load's power. However, the operational control of the microgrid still has a major issue on the operation of the microgrid. The dissertation is divided into two main sections which are:
1- Low-level control of a single smart Inverter.
2- High-level control of the microgrid.
The first part investigates a comprehensive research for a smart inverter and VSC technology at the two major connections of the microgrid. This involves controlling and modeling single smart inverter and VSC to solve specific issues of microgrid as well as improve the operation of the system. The research provides developed features for smart inverter comparing with a conventional voltage sourced converter (VSC). The two main connections for a microgrid have been deeply investigated to analyze a better way to develop and improve the operational procedure of the microgrid as well as solve specific issues of connecting the microgrid to the system.
A detailed procedure for controlling VSC and designing an optimal operation of the controller is also covered in the first part of the dissertation. This section provides an optimal operation for controlling motor drive and demonstrates issues when motor load exists at an autonomous microgrid. It also provides a solution for specific issues at operating a microgrid at autonomous mode as well as improving the structural design for the grid-tied microgrid. The solution for autonomous microgrid includes changing the operational state of the switching pattern of the smart inverter to solve the issue of a common mode voltage (CMV) that appears across the motor load. It also solves the issue of power supplying to large loads, such as induction motors. The last section of the low-level section involves an improvement of the performance and operation of the PV charging station for a plug-in hybrid electric vehicle (PHEV) at grid-tied mode. This section provides a novel structure and smart controller for PV charging station using three-phase hybrid boost converter topology. It also provides a form of applications of a multifunction smart inverter using PV charging station.
The second part of the research is focusing on improving the performance of the microgrid by integrating several smart inverters to form a microgrid. It investigates the issue of connecting DER units with the microgrid at real applications. One of the common issues of the microgrid is the circulating current which is caused by poor reactive power sharing accuracy. When more than two DER units are connected in parallel, a microgrid is forming be generating required power for the load. When the microgrid is operated at autonomous mode, all DER units participate in generating voltage and frequency as well as share the load's power. This section provides a smart and novel controlling technique to solve the issue of unequal power sharing. The feature of the smart inverter is realized by the communication link between smart inverters and the main operator. The analysis and derivation of the problem are presented in this section.
The dissertation has led to two accepted conference papers, one accepted transaction IEEE manuscript, and one submitted IET transaction manuscript. The future work aims to improve the current work by investigating the performance of the smart inverter at real applications.
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Gao, Shuang, and 高爽. "Design, analysis and control of vehicle-to-grid services." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/197100.
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There are unique challenges and opportunities related to the integration of electric vehicles into the future power grid, especially the modern distribution grid since electric vehicle (EV) charging facilities and fast-charging stations are usually tied to low-voltage and medium-voltage power networks. The grid-connected EVs, if properly controlled, can operate as distributed energy storage and provide various ancillary services, such as peak shaving, fast-response reserve capacity, frequency regulation, voltage control and reactive supports.
The purpose of this thesis is to integrate EVs to the power grid and provides suitable ancillary services to improve the grid reliability and stability. The larger future penetration of EVs and renewable energies is also taken into account to develop the vehicle-to-grid (V2G) control scheme with the constraints of EV charging and communication infrastructures. The main contents include: V2G mathematical model and system configuration; impact evaluation of EV integration and the V2G control framework; energy scheduling of EVs integration; V2G dynamic regulation services; control method of EV aggregator for dispatching a fleet of EVs; and the evaluation of V2G control scheme and hardware-in-the-loop experimental system design.
In the thesis, the impact of EV charging demand on the conventional distribution grid is firstly estimated to reveal the negative effects of the arbitrary EV charging and the necessity to control the EV charging process. The potential benefits EVs can bring into the power grid support are discussed and a V2G control framework is proposed to perform the V2G optimization and various regulation services. The current power electronics applied EV charging facilities and communication network are integrated into the V2G operation in the future distribution grid with microgrid and smaller installation of renewable generation units.
Next, mathematical model of V2G power control is formulated. Two optimization methods are proposed to schedule the EV charging and discharging energy to minimize the power losses and the operating cost while satisfying the mobility needs and the power system limitations. Subsequently, the dynamic regulation of V2G power is investigated to unleash the potential of EVs to provide multiple ancillary services simultaneously. In addition to V2G optimal energy scheduling, EVs can also be employed for dynamic power regulation which requires the fast response to the instantaneous imbalance between the power supply and demand. V2G power is controlled to mitigate the power fluctuation caused by the intermittent wind energy resources, and thus stabilize the system frequency and voltage.
Finally, an EV-centric hybrid energy storage system is proposed, which combines the merits of V2G operation and superconducting magnetic energy storage (SMES) to enhance the power quality and system frequency stability. The critical issues in V2G applications are summarized in the end.published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy
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Miao, Hui. "Innovative Heuristic Optimization Methods in Smart Grid Networks for Energy and Operation Expense Management." Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/17164.
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The smart grid is a new generation power grid in which the electricity distribution incorporates advanced communication networks which could improve the efficiency, reliability and safety for the power grid. In this thesis we explore different aspects of the smart grid and investigate the expense and management optimization problems for each aspect (e.g., smart meter networks, electric vehicles, and so on). New mathematical models are proposed to describe the problems, then new optimization algorithms and heuristic methods are proposed to solve the optimization problems. We start off with investigating how to reduce the infrastructure construction expense for a smart meter network. A novel Heuristic Best-fit Clustering approach is proposed to obtain the minimum number and the optimized locations of the powerful nodes (local data centers) which need to be built to fulfil the connectivity requirement of a smart meter network. Considering the performance of the Heuristic Best-fit Clustering approach goes worse greatly when the search space (number of smart meters) increases, two enhanced methods (Discrete Differential Evolutionary Clustering method and Particle Swarm Optimization Clustering method) are developed to improve the performance of the algorithm. Besides the smart meter network, we also investigate an operating expense optimization problem for Electric Vehicles (EVs) in a large-scale logistics and transportation network. A new Two-step Clustering Heuristic Optimization (TCHO) method is developed to minimize the total operating expense while satisfying all the constraints in the multiple depots and charge stations environment. Finally, we discuss on how to use heuristic optimization algorithms to minimize the operating cost (by obtaining the shortest routes) for vehicles in a three dimensional environment with three dimensional obstacles and dynamic targets. A Heuristic Potential Field (HPF) optimization method is proposed to find the optimal solutions.
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Kalalas, Charalampos. "Enabling LTE for Control System Applications in a Smart Grid Context." Thesis, KTH, Reglerteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-150344.
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The next generation electric power system, known as Smart Grid, is expected to alleviate the energy shortage problem by exploiting renewable energy resources. The Smart Grid communication network, with its diverse structure, constitutes an indispensable component in the new power system. In terms of power industry standards, the International Electrotechnical Commission (IEC) 61850 framework is of particular note. Originally defined to cover the stringent requirements for automation within the substation, IEC 61850 is proving to be a versatile standard that can also be applied to the medium- and low-voltage networks while facilitating control applications. Long Term Evolution (LTE) appears as a remarkable candidate for supporting remote automation tasks in the electricity grid, offering low latency, high throughput and quality of service differentiation in a single radio access technology. In the context of the thesis, a performance evaluation of the integration of LTE technology with IEC 61850 communication services is carried out. A characterization of the network architecture and the performance requirements for intelligent power system management is performed and an analytical model for the scheduling framework is proposed. Emphasis is given on the development of optimal prioritization schemes and techniques in order to ensure control data scheduling in situations when LTE background traffic coexists in the network. In addition, realistic communication scenarios specifically designed to emulate real network operations are considered and extensive simulations are performed with the use of Ericsson’s radio system simulator platform. The results have demonstrated that LTE networks successfully meet the performance requirements for wide-area automation tasks within a Smart Grid context. Given the size of the LTE ecosystem, such an evolution constitutes an attractive path for future wireless communication.
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Wang, Zhu. "Multi-agent Control for Integrated Smart Building and Micro-grid Systems." University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1372643529.
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Wang, Zhongkui. "Reactive Power Control and Optimization of Large Scale Grid Connected Photovoltaic Systems in the Smart Grid." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1388764166.
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Liu, Kai, and 劉愷. "Optimal dispatch and management for smart power grid." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46336680.
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Maknouninejad, Ali. "Cooperative Control and Advanced Management of Distributed Generators in a Smart Grid." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5663.
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Smart grid is more than just the smart meters. The future smart grids are expected to include a high penetration of distributed generations (DGs), most of which will consist of renewable energy sources, such as solar or wind energy. It is believed that the high penetration of DGs will result in the reduction of power losses, voltage profile improvement, meeting future load demand, and optimizingthe use of non-conventionalenergy sources. However, more serious problems will arise if a decent control mechanism is not exploited. An improperly managed high PV penetration may cause voltage profile disturbance, conflict with conventional network protection devices, interfere with transformer tap changers, and as a result, cause network instability. Indeed, it is feasible to organize DGs in a microgrid structure which will be connected to the main grid through a point of common coupling (PCC). Microgrids are natural innovation zones for the smart grid because of their scalability and flexibility. A proper organization and control of the interaction between the microgrid and the smartgrid is a challenge. Cooperative control makes it possible to organize different agents in a networked system to act as a group and realize the designated objectives. Cooperative control has been already applied to the autonomous vehicles and this work investigates its application in controlling the DGs in a micro grid. The microgrid power objectives are set by a higher level control and the application of the cooperative control makes it possible for the DGs to utilize a low bandwidth communication network and realize the objectives. Initially, the basics of the application of the DGs cooperative control are formulated. This includes organizing all the DGs of a microgrid to satisfy an active and a reactive power objective. Then, the cooperative control is further developed by the introduction of clustering DGs into several groups to satisfy multiple power objectives. Then, the cooperative distribution optimization is introduced to optimally dispatch the reactive power of the DGs to realize a unified microgrid voltage profile and minimizethelosses. Thisdistributedoptimizationis agradient based techniqueand itis shown that when the communication is down, it reduces to a form of droop. However, this gradient based droop exhibits a superior performance in the transient response, by eliminating the overshoots caused by the conventional droop. Meanwhile, the interaction between each microgrid and the main grid can be formulated as a Stackelberg game. The main grid as the leader, by offering proper energy price to the micro grid, minimizes its cost and secures the power. This not only optimizes the economical interests of both sides, the microgrids and the main grid, but also yields an improved power flow and shaves the peak power. As such, a smartgrid may treat microgrids as individually dispatchable loads or generators.Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
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Carlsson, Adrian. "On the Use of 5G for Smart Grid Inter-Substation Control Signaling." Thesis, Karlstads universitet, Institutionen för matematik och datavetenskap (from 2013), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-71576.
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In the energy domain today we are seeing an increasing number of energy equipments used and faceing new challenges such as network reliability, distributed renewable energy, increasing network complexity and energy efficiency. The concept of smart grid control systems has recently been seen as an appropriate way to address these new challenges. Today, the IEC 61850 standard is one of the most common standards used for power system automation. One of the services introduced is the so-called Generic Object Oriented Substation Event (GOOSE), which is a protocol to transfer time critical messages between multiple devices in a substation. The 5th generation of mobile networks (5G) are enabling new services and applications requiring lower latency, improved energy efficiency, better reliability and massive connection density. These promises of higher reliability and lower latency could then possibly be used in the future smart grid transmissions. In this work, the main goal was to understand the importance of time-critical messages, such as GOOSE messages, in the IEC61850 standard, and how these possibly could be used in the new 5th generation of mobile network. A proposed experimental setup which can be used for future research within both the GOOSE messaging area itself and the Open5GCore for emulated 5G mobile networks is presented. The intension of the experimental study is to send the GOOSE messages traversing through 5G networks by Open5GCore - an emulated 5G software.
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Tarisciotti, Luca. "Model predictive control for advanced multilevel power converters in smart-grid applications." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/27742/.
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In the coming decades, electrical energy networks will gradually change from a traditional passive network into an active bidirectional one using concepts such as these associated with the smart grid. Power electronics will play an important role in these changes. The inherent ability to control power flow and respond to highly dynamic network will be vital. Modular power electronics structures which can be reconfigured for a variety of applications promote economies of scale and technical advantages such as redundancy. The control of the energy flow through these converters has been much researched over the last 20 years. This thesis presents novel control concepts for such a structure, focusing mainly on the control of a Cascaded H-Bridge converter, configured to function as a solid state substation. The work considers the derivation and application of Dead Beat and Model Predictive controllers for this application and scrutinises the technical advantages and potential application issues of these methodologies. Moreover an improvement to the standard Model Predictive Control algorithm that include an intrinsic modulation scheme inside the controller and named Modulated Model Predictive Control is introduced. Detailed technical work is supported by Matlab/Simulink model based simulations and validated by experimental work on two converter platforms, considering both ideal and non-ideal electrical network conditions.
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Kasimir, Viktor. "Frequency Simulation at Island Grid Operation of a SGT-800 Gas Turbine." Thesis, Luleå tekniska universitet, Institutionen för system- och rymdteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-80797.
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A frequency simulation for island grid operation of a SGT-800 gas turbine has been developed using the swing equation derived for synchronous machines. With the ever expanding and changing power grid, the requirements for plants to comply with grid code is getting more strict. Accurate simulations is needed to ensure compliance with the grid codes when implementing a gas turbine into a grid. SIEMENS wants to stay on top of this as the grid code develops to ensure that their products are capable of providing what is required of them. A combination of the SIMIT and PCS7 software has been used to simulate a SGT-800 gas turbine with control system where SIMIT simulated the turbine and the control system controlled the process in PCS7. The frequency simulation comparison with real data from a SGT800 showed a satisfactory result and load changes and a full load rejection has been compared. Several benefits such as being able to answer customer questions regarding frequency effects on island grids and testing the frequency control system can be obtained. Furthermore the SIMIT solution would enable easier implementation on site since the control system and simulation model are held separate. This also implies that operator training can be easily implemented as a future project.
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Johnson, Benjamin Anders. "Modeling and Analysis of a PV Grid-Tied Smart Inverter's Support Functions." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/994.
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The general trends in the past decade of increasing solar cell efficiency, decreasing PV system costs, increasing government incentive programs, and several other factors have all combined synergistically to reduce the barriers of entry for PV systems to enter the market and expand their contribution to the global energy portfolio. The shortcomings of current inverter functions which link PV systems to the utility network are becoming transparent as PV penetration levels continue to increase. The solution this thesis proposes is an approach to control the inverters real and reactive power output to help eliminate the problems associated with PV systems at their origin and in addition provide the grid with ancillary support services. The design, modeling, and analysis of a grid-tied PV system was performed in the PSCAD software simulation environment. Results indicate that in the presence of grid disturbances the smart inverter can react dynamically to help restore the power system back to its normal state. A harmonic analysis was also performed indicating the inverter under study met the applicable power quality standards for distributed energy resources.
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Fulhu, Miraz Mohamed. "Active human intelligence for smart grid (AHISG) : feedback control of remote power systems." Thesis, University of Canterbury. Mechanical Engineering, 2014. http://hdl.handle.net/10092/9582.
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Fuel supply issues are a major concern in remote island communities and this is an engineering field that needs to be analyzed in detail for transition to sustainable energy systems. Power generation in remote communities such as the islands of the Maldives relies on power generation systems primarily dependent on diesel generators. As a consequence, power generation is easily disrupted by factors such as the delay in transportation of diesel or rises in fuel price, which limits shipment quantity. People living in remote communities experience power outages often, but find them just as disruptive as people who are connected to national power grids. The use of renewable energy sources could help to improve this situation, however, such systems require huge initial investments. Remote power systems often operate with the help of financial support from profit-making private agencies and government funding. Therefore, investing in such hybrid systems is uncommon.
Current electrical power generation systems operating in remote communities adopt an open loop control system, where the power supplier generates power according to customer demand. In the event of generation constraints, the supplier has no choice but to limit the power supplied and this often results in power cuts. Most smart grids that are being established in developed grids adopt a closed loop feedback control system. The smart grids integrated with demand side management tools enable the power supplier to keep customers informed about their daily energy consumption. Electric utility companies use different demand response techniques to achieve peak energy demand reduction by eliciting behavior change. Their feedback information is commonly based on factors such as cost of energy, environmental concerns (carbon dioxide intensity) and the risk of black-outs due to peak loads. However, there is no information available on the significant link between the constraints in resources and the feedback to the customers. In resource-constrained power grids such as those in remote areas, there is a critical relationship between customer demand and the availability of power generation resources.
This thesis develops a feedback control strategy that can be adopted by the electrical power suppliers to manage a resource-constrained remote electric power grid such that the most essential load requirements of the customers are always met. The control design introduces a new concept of demand response called participatory demand response (PDR). PDR technique involves cooperative behavior of the entire community to achieve quality of life objectives. It proposes the idea that if customers understand the level of constraint faced by the supplier, they will voluntarily participate in managing their loads, rather than just responding to a rise in the cost of energy. Implementation of the PDR design in a mini-grid consists of four main steps. First, the end-use loads have to be characterized using energy audits, and then they have to be classified further into three different levels of essentiality. Second, the utility records have to be obtained and the hourly variation factors for the appliances have to be calculated. Third, the reference demand curves have to be generated. Finally, the operator control system has to be designed and applied to train the utility operators.
A PDR case study was conducted in the Maldives, on the island of Fenfushi. The results show that a significant reduction in energy use was achieved by implementing the PDR design on the island. The overall results from five different constraint scenarios practiced on the island showed that during medium constrained situations, load reductions varied between 4.5kW (5.8%) and 7.7kW (11.3%). A reduction of as much as 10.7kW (15%) was achieved from the community during a severely constrained situation.
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Marchman, Christopher, Jacob Bertels, Dalton Gibbs, and Samuel Novosad. "Remote Monitoring and Control of Residential and Commercial Energy Use." International Foundation for Telemetering, 2014. http://hdl.handle.net/10150/577414.
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ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CAThis paper describes a device that integrates remote monitoring and control electronics into a commercial off the shelf 120 VAC power distribution strip and surge protector. An integrated microcontroller collects data on power usage from each of four AC outlets, along with two USB ports, and relays this information to a remote location. Using a conventional web browser to generate a graphical user interface, an untrained user can easily visualize their current and past energy usage patterns, and send commands to control individual outlets.
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Ono, Masahiro S. M. Massachusetts Institute of Technology. "Energy-efficient control of a smart grid with sustainable homes based on distributing risk." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/70413.
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Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 135-145).
The goal of this thesis is to develop a distributed control system for a smart grid with sustainable homes. A central challenge is how to enhance energy efficiency in the presence of uncertainty. A major source of uncertainty in a smart grid is intermittent energy production by renewable energy sources. In the face of global climate change, it is crucial to reduce dependence on fossil fuels and shift to renewable energy sources, such as wind and solar. However, a large-scale introduction of wind and solar generation to an electrical grid poses a significant risk of blackouts since the energy supplied by the renewables is unpredictable and intermittent. The uncertain behavior of renewable energy sources increases the risk of blackouts. Therefore, an important challenge is to develop an intelligent control mechanism for the electrical grid that is both reliable and efficient. Uncertain weather conditions and human behavior pose challenges for a smart home. For example, autonomous room temperature control of a residential building may occasionally make the room environment uncomfortable for residents. Autonomous controllers must be able to take residents' preferences as an input, and to control the indoor environment in an energy-efficient manner while limiting the risk of failure to meet the residents' requirements in the presence of uncertainties. In order to overcome these challenges, we propose a distributed robust control method for a smart grid that includes smart homes as its building components. The proposed method consists of three algorithms: 1) market-based contingent energy dispatcher for an electrical grid, 2) a risk-sensitive plan executive for temperature control of a residential building, and 3) a chance-constrained model-predictive controller with a probabilistic guarantee of constraint satisfaction, which can control continuously operating systems such as an electrical grid and a building. We build the three algorithms upon the chance-constrained programming framework: minimization of a given cost function with chance constraints, which bound the probability of failure to satisfy given state constraints. Although these technologies provide promising capabilities, they cannot contribute to sustainability unless they are accepted by the society. In this thesis we specify policy challenges for a smart grid and a smart home, and discuss policy options that gives economical and regulatory incentives for the society to introduce these technologies on a large scale.
by Masahiro Ono.
S.M.in Technology and Policy
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Zhao, Junbo. "A Robust Dynamic State and Parameter Estimation Framework for Smart Grid Monitoring and Control." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/83423.
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The enhancement of the reliability, security, and resiliency of electric power systems depends on the availability of fast, accurate, and robust dynamic state estimators. These estimators should be robust to gross errors on the measurements and the model parameter values while providing good state estimates even in the presence of large dynamical system model uncertainties and non-Gaussian thick-tailed process and observation noises. It turns out that the current Kalman filter-based dynamic state estimators given in the literature suffer from several important shortcomings, precluding them from being adopted by power utilities for practical applications. To be specific, they cannot handle (i) dynamic model uncertainty and parameter errors; (ii) non-Gaussian process and observation noise of the system nonlinear dynamic models; (iii) three types of outliers; and (iv) all types of cyber attacks. The three types of outliers, including observation, innovation, and structural outliers are caused by either an unreliable dynamical model or real-time synchrophasor measurements with data quality issues, which are commonly seen in the power system.
To address these challenges, we have pioneered a general theoretical framework that advances both robust statistics and robust control theory for robust dynamic state and parameter estimation of a cyber-physical system. Specifically, the generalized maximum-likelihood-type (GM)-estimator, the unscented Kalman filter (UKF), and the H-infinity filter are integrated into a unified framework to yield various centralized and decentralized robust dynamic state estimators. These new estimators include the GM-iterated extended Kalman filter (GM-IEKF), the GM-UKF, the H-infinity UKF and the robust H-infinity UKF. The GM-IEKF is able to handle observation and innovation outliers but its statistical efficiency is low in the presence of non-Gaussian system process and measurement noise. The GM-UKF addresses this issue and achieves a high statistical efficiency under a broad range of non-Gaussian process and observation noise while maintaining the robustness to observation and innovation outliers. A reformulation of the GM-UKF with multiple hypothesis testing further enables it to handle structural outliers. However, the GM-UKF may yield biased state estimates in presence of large system uncertainties. To this end, the H-infinity UKF that relies on robust control theory is proposed. It is shown that H-infinity is able to bound the system uncertainties but lacks of robustness to outliers and non-Gaussian noise. Finally, the robust H-infinity filter framework is proposed that leverages the H-infinity criterion to bound system uncertainties while relying on the robustness of GM-estimator to filter out non-Gaussian noise and suppress outliers. Furthermore, these new robust estimators are applied for system bus frequency monitoring and control and synchronous generator model parameter calibration. Case studies of several different IEEE standard systems show the efficiency and robustness of the proposed estimators.Ph. D.
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Moghbel, Moayed. "Online Control of Modular Active Power Line Conditioner to Improve Performance of Smart Grid." Thesis, Curtin University, 2016. http://hdl.handle.net/20.500.11937/51891.
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This thesis is explored the detrimental effects of nonlinear loads in distribution systems and investigated the performances of shunt FACTS devices to overcome these problems with the following main contribution: APLC is an advanced shunt active filter which can mitigate the fundamental voltage harmonic of entire network and limit the THDv and individual harmonic distortion of the entire network below 5% and 3%, respectively, as recommended by most standards such as the IEEE-519.
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Johansson, Henrik, and Lucas Tunelid. "Operation and Control of HVDC Grids." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-293882.
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In order to meet the increasing demand ofenergy in today’s society while at the same time minimizing theenvironmental impact, renewable energy sources will be requiredto be integrated into the existing energy mix. Technologicaladvances in high voltage direct current (HVDC) grids playa crucial role in making this possible. Therefore the purposeof this project has been to validate the properties of basiccontrol strategies in terms of how they respond to four differentsimulation cases. All simulations have been conducted on asimplified version of the CIGR ́E B4 test grid, consisting offour monopolar HVDC converters. After analyzing the resultsobtained from each control strategy it became evident thatprovided if the benefits of the redundancy introduced by amulti-terminal grid are to be fully utilized, a distributed voltagecontrol should be used. Moreover, after substituting one ofthe four internal controllers with an external one, it becameclear that simply deciding the droop constants based on resultsfrom the simulation model wouldn’t be sufficient for real worldapplications.För att möta det ökande energibehovet i dagens samhälle, samtidigt som energiproduktionens miljöpåverkan ska minimeras, krävs det att förnyelsebara energikällor integreras i den existerande energimixen. Tekniska framsteg inom högspända likströmsnät (HVDC) spelar en avgörande roll i att göra detta möjligt. Därför har syftet med detta projekt varit att validera egenskaperna hos grundläggande kontrollstrategier efter hur dem reagerar på fyra olika simuleringsfall. Alla simuleringar har genomförts på en förenklad version av CIGRE´ B4 testsystem, bestående av fyra monopolära HVDC omriktare. Efter att analyserat de erhållna resultaten från varje kontrollstrategi blev det uppenbart att om fördelarna med multiterminala elnät skulle uppnås, bör en distribuerad spänningskontroll användas. Dessutom, efter att ha bytt ut en av dem fyra interna kontrollerna med en extern, visade det sig att endast bestämma droppkonstanterna baserat på resultat från simuleringsmodellen inte är tillräckligt för verkliga applikationer.
Kandidatexjobb i elektroteknik 2020, KTH, Stockholm
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Bianchi, Adam, and Gabriel Nylander. "Operation and Control of HVDC Grids." Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-229460.
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Meshed high-voltage direct current grids are becoming an increasingly important technology for integrating renewable energies into the power system. To control the grids in the best possible way, optimal converter and grid control strategies are needed. This project studies how a four-terminal high-voltage direct current grid is operated and controlled by implementing different grid and converter control strategies. The grid control strategies examined are centralized voltage control and distributed voltage control with and without deadband. Simulations are made in the software PSCAD. Different fault types on the grid are studied to investigate how the power flow and voltage level are affected. An optimal value for both the deadband width and droop constant has been identified. Moreover, the results indicate that centralized droop control is not a suitable grid control strategy, whereas distributed voltage control with and without deadband are. The fault study indicates no differences between distributed voltage control with and without deadband. The power flow and voltage levels are identical for all fault types.Högspända likströmsnät spelar en allt större roll med att integrera förnyelsebar energi i våra elnät. För att styra dessa nät på bästa möjliga sätt krävs optimala omvandlar- och nätkontrollstrategier. I detta projekt studeras hur ett fyrterminalt högspänt likströmsnät kan styras och drivas genom att implementera olika omvandlar- och nätkontrollstrategier. De nätkontrollstrategier som studerats är centraliserad spänningskontroll och distribuerad spänningskontroll med och utan ett spänningsintervall. Alla simuleringar har utförts i programmet PSCAD. Olika fel i nätet har även studerats för att undersöka hur effektflödet och spänningsnivån påverkas. Ett optimalt värde på både spänningsintervallet och droop konstanten har identifierats. Dessutom har resultat som indikerar att centraliserad spänningskontroll inte är en lämplig nätkontrollstrategi erhållits, medan distribuerad spänningskontroll med och utan spänningsintervall är det. Felsimuleringarna påvisar ingen skillnad mellan distribuerad spänningskontroll med och utan spänningsintervall. Effektflödet och spänningsnivån är identiska för alla fel.
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Geury, Thomas. "Smart matrix converter-based grid-connected photovoltaic system for mitigating current and voltage-related power quality issues on the low-voltage grid." Doctoral thesis, Universite Libre de Bruxelles, 2017. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/243967.
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The increasing penetration of distributed energy resources, in particular Photovoltaic (PV) production units, and the ever-growing use of power electronics-based equipment has led to specific concern about Power Quality (PQ) in the Low-Voltage (LV) grid. These include high- and low-order current harmonics as well as voltage distortion at the point of common coupling. Solutions to overcome these issues, meeting international grid codes, are being proposed in the context of smart energy management schemes.This work proposes a novel three-phase topology for a PV system with enhanced PQ mitigation functionality, tackling the corresponding control challenges.First, a single-stage current-source inverter PV system with active filtering capability is preferred to the more common two-stage voltage-source inverter topology with additional voltage-step-up converter. The system also guarantees a nearly unitary displacement power factor in the connection to the grid and allows for Maximum Power Point Tracking (MPPT) with direct control of the PV array power. The grid-synchronised dq-axis grid current references are generated for the mitigation of nonlinear load low-order current harmonics, without the need for additional measurements. Active damping is used to minimise grid-side filter losses and reduce high-order harmonics resulting from the converter switching.Results on a 500W laboratory prototype confirm that active damping reduces the switching harmonics in the grid currents and active filtering properly mitigates the low-order current harmonics. The MPPT algorithm works effectively for various irradiance variations. Second, a PV system with a novel Indirect Matrix Converter (IMC)-based unified power quality conditioner topology is developed for enhanced current and voltage compensation capability, with compactness and reliability advantages. PQ issues such as current harmonics, and voltage sags, swells, undervoltage and overvoltage are mitigated by the shunt and series converters, respectively.The more common Space Vector Modulation (SVM) method used in IMCs is developed for this specific topology. In particular, a new shunt converter modulation method is proposed to additionally control the PV array current with zero switching vectors, resulting in a specific switching sequence.A direct sliding mode control method is also studied separately for the shunt and series converters, so that the zero-vector modulation method of the shunt converter can be used, with no sensitive synchronisation of the switching signals; this contrasts with the SVM method. A new dc link voltage modulation method with 12 voltage zones, instead of 6, is proposed to help overcome the limitation in the choice of shunt converter switching vectors due to the positive dc link voltage constraint.Results are obtained for the direct method on a 1 kW laboratory prototype with optimised IMC dc link connection and alternative shunt converter switching transitions to guarantee a positive dc link voltage. Current and voltage compensation capabilities are confirmed by tests in various operating conditions.Doctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished
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Paridari, Kaveh. "Optimal and Resilient Control with Applications in Smart Distribution Grids." Licentiate thesis, KTH, Reglerteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-191307.
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The electric power industry and society are facing the challenges and opportunities of transforming the present power grid into a smart grid. To meet these challenges, new types of control systems are connected over IT infrastructures. While this is done to meet highly set economical and environmental goals, it also introduces new sources of uncertainty in the control loops. In this thesis, we consider control design taking some of these uncertainties into account. In Part I of the thesis, some economical and environmental concerns in smart grids are taken into account, and a scheduling framework for static loads (e.g., smart appliances in residential areas) and dynamic loads (e.g., energy storage systems) in the distribution level is investigated. A robust formulation is proposed taking the user behavior uncertainty into account, so that the optimal scheduling cost is less sensitive to unpredictable changes in user preferences. In addition, a novel distributed algorithm for the studied scheduling framework is proposed, which aims at minimizing the aggregated electricity cost of a network of apartments sharing an energy storage system. We point out that the proposed scheduling framework is applicable to various uncertainty sources, storage technologies, and programmable electrical loads. In Part II of the thesis, we study smart grid uncertainty resulting from possible security threats. Smart grids are one of the most complex cyber-physical systems considered, and are vulnerable to various cyber and physical attacks. The attack scenarios consider cyber adversaries that may corrupt a few measurements and reference signals, which may degrade the system’s reliability and even destabilize the voltage magnitudes. In addition, a practical attack-resilient framework for networked control systems is proposed. This framework includes security information analytics to detect attacks and a resiliency policy to improve the performance of the system running under the attack. Stability and optimal performance of the networked control system under attack and by applying the proposed framework, is proved here. The framework has been applied to an energy management system and its efficiency is demonstrated on a critical attack scenario.QC 20160830
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Battegay, Archie. "Valorisation des gisements de flexibilité dans les investissements de smart grid." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT092/document.
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Les travaux de recherche présentés dans ce mémoire visent à évaluer des économies d'investissement inhérentes à l'implémentation du pilotage de charge. Pour ce faire, l'approche que nous avons proposée s'inscrit dans l'analyse de l'adéquation des infrastructures électriques avec les projections de la demande. Dans cette perspective, les travaux de modélisation que nous avons développés s'articulent en trois étapes. Premièrement, la capacité du pilotage de charge à modifier les appels des consommateurs a été évaluée. Le modèle que nous proposons tient à la fois compte des effets de bord des effacements de consommation et des limites de disponibilité des flexibilités des consommateurs. Sur la base de cette modélisation, nous avons proposé un modèle évaluant l'apport de ce pilotage pour l'équilibre offre-demande à long terme. Ce modèle quantifie les économies d'investissement dans les capacités de production que pourraient permettre des flexibilités au sein de la demande électrique. Enfin, nous avons complété cette approche en évaluant l'impact de ces flexibilités dans le dimensionnement des réseaux électriques. L'application de nos modèles à un scénario énergétique élaboré au sein du projet GreenLys a permis de dégager quelques conclusions importantes. Ainsi, l'essentiel des économies d'infrastructures induites par le pilotage de charge concerne les capacités de production. Néanmoins, une utilisation des flexibilités des consommateurs optimale pour l'équilibre offre-demande se traduit localement par des coûts d'infrastructure accrus. En particulier, nos simulations mettent en évidence qu'un tel pilotage de charge, optimal à l'échelle nationale, induit localement une augmentation des transits sur les heures les plus chargées de l'année. Aussi, nous avons montré que des modifications ponctuelles des programmes d'appel optimaux pour l'équilibre offre-demande suffisent à dégager des bénéfices pour l'ensemble du système électrique. Dans le cadre de notre étude, ces modifications sont motivées par les situations de défaillance probable des réseaux. Ces défaillances résultent de la concomitance d'aléas climatiques et techniques défavorables. L'analyse que nous avons produite révèle qu'en l'absence de prise en compte de la situation spécifique des réseaux de distribution, les intersaisons et les heures creuses pourraient devenir plus critiques dans la gestion de ces réseaux qu'elles ne le sont aujourd'huiThe research presented in this report aims to evaluate investment savings related to the implementation of direct load control. To this end, the proposed approach fits into the framework of system adequacy analysis. In this perspective, the models that we have developed are structured in three stages. First, the ability of the direct load control to change consumer demand has been evaluated. The model we have proposed takes into account the side effects of load shedding and the limits of the consumer availability . Based on this model, we have proposed a model in order ro assess the contribution of this control to the long-term supply-demand balance. This model quantifies the investment savings in production capacity led by electric demand flexibilities. Finally, we completed this approach by evaluating the impact of these flexibilities in the design of electrical networks. These models have been applied to an energy scenario that has been developped in the GreenLys project. The simulations led to indentifysome important conclusions. Thus, most of the infrastructure savings induced by direct load controls deal with production capacities. Nevertheless, the optimal use of flexibilities optimal for consumer supply-demand balance is reflected locally by an increase in networks costs. In particular, our simulations show that such a load control strategy, which is optimal on the national level, locally induces an increase in power flows during the most loaded period of the year. Also, we have shown that slight modifications in consumers call programs are sufficient to generate profits for the entire electrical system. In the context of our study, these changes are motivated by the possible networks failures. These failures result from the conjunction of unfavorable climatic and technical hazards. The analysis that we have produced shows that misconsidering the specific situation of distribution networks could lead the shoulder season and the off-peak hours to become more critical in the management of these networks
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Wang, Wenyuan. "Operation, control and stability analysis of multi-terminal VSC-HVDC systems." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/operation-control-and-stability-analysis-of-multiterminal-vschvdc-systems(f428f63c-f9b9-4faa-9618-7b6e645a8636).html.
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Voltage source converter high voltage direct current (VSC-HVDC) technology has become increasingly cost-effective and technically feasible in recent years. It is likely to play a vital role in integrating remotely-located renewable generation and reinforcing existing power systems. Multi-terminal VSC-HVDC (MTDC) systems, with superior reliability, redundancy and flexibility over the conventional point-to-point HVDC, have attracted a great deal of attention globally. MTDC however remains an area where little standardisation has taken place, and a series of challenges need to be fully understood and tackled before moving towards more complex DC grids. This thesis investigates modelling, control and stability of MTDC systems. DC voltage, which indicates power balance and stability of DC systems, is of paramount importance in MTDC control. Further investigation is required to understand the dynamic and steady-state behaviours of various DC voltage and active power control schemes in previous literature. This work provides a detailed comparative study of modelling and control methodologies of MTDC systems, with a key focus on the control of grid side converters and DC voltage coordination. A generalised algorithm is proposed to enable MTDC power flow calculations when complex DC voltage control characteristics are employed. Analysis based upon linearised power flow equations and equivalent circuit of droop control is performed to provide further intuitive understanding of the steady-state behaviours of MTDC systems. Information of key constraints on the stability and robustness of MTDC control systems has been limited. A main focus of this thesis is to examine these potential stability limitations and to increase the understanding of MTDC dynamics. In order to perform comprehensive open-loop and closed-loop stability studies, a systematic procedure is developed for mathematical modelling of MTDC systems. The resulting analytical models and frequency domain tools are employed in this thesis to assess the stability, dynamic performance and robustness of active power and DC voltage control of VSC-HVDC. Limitations imposed by weak AC systems, DC system parameters, converter operating point, controller structure, and controller bandwidth on the closed-loop MTDC stability are identified and investigated in detail. Large DC reactors, which are required by DC breaker systems, are identified in this research to have detrimental effects on the controllability, stability and robustness of MTDC voltage control. This could impose a serious challenge for existing control designs. A DC voltage damping controller is proposed to cope with the transient performance issues caused by the DC reactors. Furthermore, two active stabilising controllers are developed to enhance the controllability and robust stability of DC voltage control in a DC grid.
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Das, Debrup. "Dynamic control of grid power flow using controllable network transformers." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/43739.
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The objective of the research is to develop a cost-effective, dynamic grid controller called the controllable network transformer (CNT) that can be implemented by augmenting existing load tap changing (LTC) transformers with an AC-AC converter. The concept is based on using a fractionally rated direct AC-AC converter to control the power through an existing passive LTC. By using a modulation strategy based on virtual quadrature sources (VQS), it is possible to control both the magnitude and the phase angle of the output voltage of the CNT without having any inter-phase connections. The CNT architecture has many advantages over existing power flow controllers, like absence of low frequency storage, fractional converter rating, retro-fitting existing assets and independent per-phase operation making it potentially attractive for utility applications.
The independent control of the magnitude and the phase angle of the output voltage allow independent real and reactive power flow control through the CNT-controlled line. In a meshed network with asymmetric network stresses this functionality can be used to redirect power from critically loaded assets to other relatively under-utilized parallel paths. The power flow controllability of CNT can thus be used to lower the overall cost of generation of power. The solid state switches in the CNT with fast response capability enable incorporation of various additional critical functionalities like grid fault ride through, bypassing internal faults and dynamic damping. This bouquet of features makes the CNT useful under both steady state and transient conditions without compromising the grid reliability.
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Braun, Philipp [Verfasser], and Lars [Akademischer Betreuer] Grüne. "Hierarchical distributed optimization and predictive control of a smart grid / Philipp Braun ; Betreuer: Lars Grüne." Bayreuth : Universität Bayreuth, 2016. http://d-nb.info/1114270695/34.
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Braun, Philipp Verfasser], and Lars [Akademischer Betreuer] [Grüne. "Hierarchical distributed optimization and predictive control of a smart grid / Philipp Braun ; Betreuer: Lars Grüne." Bayreuth : Universität Bayreuth, 2016. http://nbn-resolving.de/urn:nbn:de:bvb:703-epub-2987-8.
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Lefort, Antoine. "A smart grid ready building energy management system based on a hierarchical model predictive control." Thesis, Supélec, 2014. http://www.theses.fr/2014SUPL0010/document.
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L’intégration des énergies renouvelables produites par un bâtiment et les réseaux de fourniture, qui sont amenés à proposer des tarifications et des puissances disponibles variables au cours de la journée, entraînent une grande variabilité de la disponibilité de l’énergie. Mais les besoins des utilisateurs ne sont pas forcément en accord avec cette disponibilité. La gestion de l’énergie consiste alors à faire en sorte que les moments de consommation des installations coïncident avec les moments où celle-ci est disponible. Notre objectif a été de proposer une stratégie de commande prédictive, distribuée et hiérarchisée, pour gérer efficacement l’énergie de l’habitat. Les aspects prédictifs de notre approche permettent d’anticiper les besoins et les variations de la tarification énergétique. L’aspect distribué va permettre d’assurer la modularité de la structure de commande, pour pouvoir intégrer différents usages et différentes technologies de manière simple et sans faire exploser la combinatoire du problème d’optimisation résultantElectrical system is under a hard constraint: production and consumption must be equal. The production has to integrate non-controllable energy resources and to consider variability of local productions. While buildings are one of the most important energy consumers, the emergence of information and communication technologies (ICT) in the building integrates them in smart-grid as important consumer-actor players. Indeed, they have at their disposal various storage capacities: thermal storage, hot-water tank and also electrical battery. In our work we develop an hierarchical and distributed Building Energy Management Systems based on model predictive control in order to enable to shift, to reduce or even to store energy according to grid informations. The anticipation enables to plan the energy consumption in order to optimize the operating cost values, while the hierarchical architecture enables to treat the high resolution problem complexity and the distributed aspect enables to ensure the control modularity bringing adaptability to the controller
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Girbau, Llistuella Francesc. "Contribution to the operation of smart rural distribution grid with energy resources for improvement of the quality of service." Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/664646.
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This Thesis aims for contributing in the deployment and operation of Smart Grid, in isolated rural areas. As it would be expected, technological developments and investments in the electrical field have mainly focused on urban and industrial areas where the energy demand is high, as well as, the possibility to recover easily the investment. Therefore, difficult accessing areas where population and electrical demand are low are less attractive to invest.
For this reason, this Thesis, in parallel to the European project known as Smart Rural Grid, has focused on the rural grid development. In this sense, the Thesis contributes directly in the design, conception and justification of an innovate architecture for rural systems. The architecture has been deployed and tested at the end of a medium voltage line of Estabanell Energia in Vallfogona del Ripollès. In addition, the presented architecture is characterised to integrate power electronics with embedded battery systems, an innovative management system and a proper telecommunication network in order to gain robustness, flexibility and hosting capacity for distributed and renewable generation.
To sum up, the Thesis has focused on the design and development of new operation modes, algorithms and equipment that allow to manage automatically and optimally the energy resources; like power electronics, energy storage systems, distributed and renewable generation, and controllable loads. These strategies are able to correct common issues in rural grids, such as voltage variations and electrical losses. In addition, they improve and ensure the power quality and supply continuity, contribute to reduce operational costs and infrastructure optimization and deferral.Aquesta tesi vol contribuir en el desplegament de les futures xarxes elèctriques intel.ligents, en entorns rurals que habitualment són oblidats. Cal mencionar que els principals avenços tecnològics i les inversions per part dels gestors de la xarxa s'han centrat en entorns urbans i industrials, ja que aquests solen demandar grans quantitats d'energia, fet que facilita la recuperació de la inversió. Per tant, en un entorn on la densitat de població i la demanda energètica és baixa i a més l'orografia és complexa resulta menys atractiu invertir-hi. Per aquest motiu, la tesi, en paral.lel al projecte Europeu Smart Rural Grid, s'ha centrat en el desenvolupament de les xarxes elèctriques en entorns rurals. El principal objectiu de la tesi i alhora del projecte Smart Rural Grid és desenvolupar tecnologies per concebre les futures xarxes en entorns rurals. Aquestes han de permetre incrementar la baixa eficiència, qualitat i resiliència de la xarxa. En aquest sentit, la tesi ha contribuït en la concepció, disseny i justificació d'una innovadora arquitectura. Aquesta arquitectura, s'ha dut a terme en el final d'una línia de mitja tensió d'Estabanell Energia a Vallfogona del Ripollès. A més, aquesta arquitectura es caracteritza per integrar electrònica de potència, sistemes elèctrics d'emmagatzemament, un innovador sistema de gestió i de telecomunicacions, poden proporcionar a la xarxa una major robustesa, flexibilitat i capacitat per integrar a la nova generació distribuïda i renovable. D'altre banda, la Tesi també s'ha centrat en la concepció i desenvolupament de nous modes d'operació, algoritmes i dispositius que permeten automatitzar i optimitzar la gestió dels recursos distribuïts; és a dir, la electrònica de potència, els sistemes d'emmagatzemament, la generació renovable i distribuïda i les càrregues controlables. Aquestes estratègies permeten solventar els problemes habituals en aquest tipus de xarxes, com per exemple les variacions de tensió i les pèrdues. A més, també milloren i asseguren la qualitat i continuïtat del subministrament, ajuden a reduir els costos d'operació i retrassar la inversió en nova infraestructura
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Golshani, Mohammad. "Novel performance evaluation of information and communication technologies to enable wide area monitoring systems for enhanced transmission network operation." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/11918.
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The penetration of renewable energy sources has increased significantly in recent years due to the ongoing depletion of conventional resources and the transition to a low carbon energy system. Renewable energy sources such as wind energy are highly intermittent and unpredictable in nature, which makes the operation of the power grid more dynamic and therefore more complex. In order to operate the power system reliably under such conditions, Phasor Measurement Units (PMUs) through the use of satellite technology can offer a state-of-the-art Wide Area Monitoring System (WAMS) for improving power system monitoring, control and protection. They can improve the operation by providing highly precise and synchronised measurements near to real-time with higher frequency and accuracy. In order to achieve such objectives, a high-speed and reliable communications infrastructure is required to transfer time-critical PMU data from remote locations to the control centre. The signals measured by PMUs are transmitted across Local and Wide Area Networks, where they may encounter excessive delays. Signal delays can have a disruptive effect and make applications at best inefficient and at worse ineffective. The main research contribution of this thesis is the performance evaluation of communication infrastructures for WAMS. The evaluation begins from inside substations and continues over wide areas from substations to control centre. Through laboratory-based investigations and simulations, the performance of communications infrastructure in a typical power system substation has been analysed. In addition, the performance evaluation of WAMS communications infrastructure has been presented. In the modelling and analysis, an existing WAMS as installed on the GB transmission system has been considered. The actual PMU packets as received at the Phasor Data Concentrator (PDC) were captured for latency analysis. A novel algorithmic procedure has been developed and implemented to automate the large-scale latency calculations. Furthermore, the internal delays of PMUs have been investigated, determined and analysed. Subsequently, the WAMS has been simulated and detailed comparisons have been performed between the simulated model results and WAMS performance data captured from the actual WAMS. The validated WAMS model has been used for analysing possible future developments as well as to test newly proposed mechanisms, protocols, etc. in order to improve the communications infrastructure performance.
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Arafat, Md Nayeem. "Modeling and Control of Distributed Energy Systems during Transition Operation between Grid Connected and Standalone Modes." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1405888130.
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