• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 15
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 28
  • 13
  • 12
  • 9
  • 8
  • 8
  • 7
  • 6
  • 6
  • 6
  • 6
  • 6
  • 4
  • 4
  • 4
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The Confirmation of Two TPB-Based Energy Saving Models

Lin, Shis-ping 03 September 2012 (has links)
The reduction green house gases (GHG) and migitation of climate change have become great challenges to mankind. Taiwan¡¦s households, which account for about 13% of the GHG emissions in Taiwan, are certainly a target for GHS and energy reduction. Based on the theory of planned behavior and Stern and Gardner's (1981) typology of energy saving behavior, this study proposed a model of curtailment behavior toward climate change (CCC model) and a model of efficiency action toward climate change (ECC model). Results of confirmatory factor analysis showed that both models were useful. The CCC model could predict people's intent to take curtailment actions and actual behavior, whereas the ECC model could predict people's intent to take efficiency actions. However, the functions of independent variables were different by gender in both models. Subjective norm influnce the dependent variable significantly only in ECC model. This study suggests some energy saving methods, according to the literatures and the findings.
2

Evaluation de produits d'effacement sur un ensemble de consommateurs par modélisation bottom-up d'un parc de logements / Assessment of heating loads shedding at large scale through bottom-up modelling of housing stocks

Carloganu, Sinziana 08 December 2016 (has links)
Cette thèse se propose d’évaluer les produits d’effacement réalisés sur un ensemble de consommateurs, chacun étant défini par le triplet {bâtiment, systèmes, ménage}. On définit un produit d’effacement par la caractérisation de la déformation de la courbe de charge de l’ensemble des consommateurs suite à l’envoi d’un signal de contrôle (pilotage direct ou signal tarifaire).Deux dimensions ont été considérées dans le cadre de ce travail : l’étude des variables d’influence sur les effacements de consommation en s’appuyant sur des données issues d’expérimentations ainsi que l’élaboration d’un modèle global permettant de reproduire une partie de la diversité observée sur les courbes de charge des clients expérimentateurs.Afin d’analyser un échantillon {bâtiments, systèmes, ménages}, une attention particulière est portée à la dispersion des caractéristiques du bâti (enveloppes, expositions, ...) et aux éventuelles corrélations entre le ménage (mode de vie, choix des équipements, ...) et les systèmes (caractéristiques techniques), notamment pour l’usage "chauffage et climatisation".Un travail de réconciliation de données (issues de statistiques, de travaux sur la caractérisation des logements métropolitains, d’études sur les habitudes de vie des ménages, ...) a permis de proposer une première évaluation en simulation d’effacement de l’usage chauffage au périmètre d’un parc de quelques milliers de logements.L’approche bottom-up proposée permet ainsi de rendre compte de la diversité technique, fonctionnelle et d’origine comportementale de l’usage étudié. / This thesis aims at evaluating load curtailments packages over a set of electricity users, each being defined by the triolet {building, system, household}. We define a load curtailment package by the quantification of the load curve's deformation due to the emission of a control signal (direct control or price incentive).Two dimensions were considered through this work: first the study of the different variables' influence using experimental data, and secondly the construction of a global model which can effectively reproduce the diversity observed on experimental load curves.In order to analyse a sample {building, system, household}, the dispersion of the different caracteristics of the building (envelope, exposure,...) were carefully studied, as well as the possible links between the household (lifestyle, choice of household equipments,...) and the systems (technical caracteristics) especially for the electrical heaters and HVAC systems.We work to reconcile data from different sources (statistical data, data from research on urban building caracterization, on households' habits,...) and we are able to give a first evaluation of load curtailment products over the electrical heating usage in urban environment through numerical simulations of a few thousand housings. The bottom-up approach used accounts for the technical diversity, as well as the functional and behavioral diversity of the studied electrical usage.
3

Probabilistic curtailment analysis for transmission grid planning using Active Network Management

Faghihi, Farshid 27 April 2015 (has links)
According to the EU Council in 2007, a target of 20% Renewable Energy Sources (RES) energy share was determined by the year 2020. Maximizing RES penetration, whilst simultaneously ensuring grid stability and security of electric supply, has become a major challenge for the grid operators. The aggregated effect of Distributed Generation (DG) units will affect increasingly the transmission grid operation and planning. More and more, the High Voltage (HV) grid has to export the excess of power produced at the Medium Voltage (MV) level, where DG units are connected. The energy flows become variable both in value and direction in substations at the interface with distribution networks, which is a complete change for the grid operator. Power flow congestions and voltage problems are particularly more likely to arise. Systematically reinforcing the network in order to absorb the last MWh produced by DG units located in unfavorable areas, while maintaining the traditional operation of the grid, is not efficient, i.e. neither economically viable for the community nor acceptable from the point of view of environmental impact. The intermittency of DG units makes it irrelevant to define the amount of connectable units on the basis of their installed power and the N-1 criterion. New paradigms to increase the grid capacity of accepting DG units before reinforcement are to be considered. And new methodologies for long-term and operational grid planning, giving allowance to this inherent variability in the generation, are therefore necessary.Active Network Management (ANM) allows to moving away from conventional grid operation towards a new approach, comprising (almost) real-time supervision and control of the DG units and network elements. Thanks to this new management of the system and accounting for the intermittent (i.e. weather-dependent) RES production, more DG units can be connected to an existing grid: the power produced by some DG units can be curtailed to eliminate possible congestions encountered for specific combinations of loads, generations and weather conditions. In others words, the use of an ANM scheme makes possible to maximize the grid utilization in enhancing the required flexibility of system operation to maintain power system security margins.A reasonable level of security in applying ANM is however required and it must be assessed before any possible application to the grid. This assessment can be performed based on a probabilistic approach: the uncertain parameters, i.e. each load and power produced by a DG unit, are modeled with probability density functions (pdf’s); the latter are then randomly sampled, to create so-called variants. These variants serve as input data for an Optimal Power Flow (OPF) module to find the possible redispatching or curtailment that could be necessary in each case. The state space is extremely vast, however, due to combinatorial explosion. Creating a sufficiently large sample of variants to cover all significant situations the grid can face appears intractable, and alternative approaches, combining a systematic search in the state space with an acceptable computation time, are to be developed.This research proposes a pragmatic methodology to handle the high dimensionality of the problem and estimate the impact of connecting a new DG unit, via the computation of several risk indices. A systematic approach guarantees searching all over the plausible congestion zones of the state space, while an on-target sampling drives the computational effort towards the direction of interest. This combined approach allows managing the computation time without falling into oversimplification or losing too much accuracy. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished
4

Adaptive control for active distribution networks

Sansawatt, Thipnatee Punim January 2012 (has links)
Rise of the global environmental awareness and climate change impacts caused by greenhouse gases emissions brings about a revolution in the power and energy industries to reduce fossil fuels and promote low-carbon and renewable distributed generation (DG). The new dimensions, mainly encouraged by the governments’ legislative targets and incentives, have allowed the development of DG worldwide. In the U.K., renewable DG especially wind is being connected on distribution networks and ranges widely in scales. Despite the growing number of potential DG sites, the surplus generation present on the passive networks can lead to some technical problems. In particular, rural networks where wind farms exist are prone to voltage rise and line thermal constraints. In order to accommodate new DG and ensure security of supply and network reliability, active management to mitigate these issues are required. In addition, the duties to provide cost-effective DG connections at avoided expensive investment incurred from conventional solutions, e.g., reinforcement and maintain robust network are a major challenge for Distribution Network Operators (DNOs). This thesis endeavours to develop an adaptive control scheme that provides local and real-time management against voltage variations and line capacity overload at the point of wind connections on rural distribution networks. Taking into account maximising power exports and providing an economically-viable control scheme, the wind turbine’s capability, comprising reactive power control and active power curtailment, is used. Whilst the thesis concentrates on the decentralised control applying several different algorithms, in addition, semi-coordinated and centralised approaches that adopt on-load tap changing transformers’ regulation and Optimal Power Flow tool are developed. Comparisons of these approaches based upon measures, i.e., economics, DG penetration and performance are determined. As an outcome, the developed scheme can enable growing integration of renewable DG on distribution networks and can be seen as an interim solution for the DNOs towards Smart Distribution Networks.
5

Improved Self-Consumption of Photovoltaic Electricity in Buildings : Storage, Curtailment and Grid Simulations

Luthander, Rasmus January 2016 (has links)
The global market for photovoltaics (PV) has increased rapidly: during 2014, 44 times more was installed than in 2004, partly due to a price reduction of 60-70% during the same time period. Economic support schemes that were needed to make PV competitive on the electricity market have gradually decreased and self-consumption of PV electricity is becoming more interesting internationally from an economic perspective. This licentiate thesis investigates self-consumption of residential PV electricity and how more PV power can be allowed in and injected into a distribution grid. A model was developed for PV panels in various orientations and showed a better relative load matching with east-west-oriented compared to south-oriented PV panels. However, the yearly electricity production for the east-west-system decreased, which resulted in less self-consumed electricity. Alternatives for self-consumption of PV electricity and reduced feed-in power in a community of detached houses were investigated. The self-consumption increased more with shared batteries than with individual batteries with identical total storage capacity. A 50% reduction in feed-in power leads to losses below 10% due to PV power curtailment. Methodologies for overvoltage prevention in a distribution grid with a high share of PV power production were developed. Simulations with a case with 42% of the yearly electricity demand from PV showed promising results for preventing overvoltage using centralized battery storage and PV power curtailment. These results show potential for increasing the self-consumption of residential PV electricity with storage and to reduce stress on a distribution grid with storage and power curtailment. Increased self-consumption with storage is however not profitable in Sweden today, and 42% of the electricity from PV is far more than the actual contribution of 0.06% to the total electricity production in Sweden in 2014.
6

Maximising renewable hosting capacity in electricity networks

Sun, Wei January 2015 (has links)
The electricity network is undergoing significant changes in the transition to a low carbon system. The growth of renewable distributed generation (DG) creates a number of technical and economic challenges in the electricity network. While the development of the smart grid promises alternative ways to manage network constraints, their impact on the ability of the network to accommodate DG – the ‘hosting capacity’- is not fully understood. It is of significance for both DNOs and DGs developers to quantify the hosting capacity according to given technical or commercial objectives while subject to a set of predefined limits. The combinational nature of the hosting capacity problem, together with the intermittent nature of renewable generation and the complex actions of smart control systems, means evaluation of hosting capacity requires appropriate optimisation techniques. This thesis extends the knowledge of hosting capacity. Three specific but related areas are examined to fill the gaps identified in existing knowledge. New evaluation methods are developed that allow the study of hosting capacity (1) under different curtailment priority rules, (2) with harmonic distortion limits, and (3) alongside energy storage systems. These works together improve DG planning in two directions: demonstrating the benefit provided by a range of smart grid solutions; and evaluating extensive impacts to ensure compliance with all relevant planning standards and grid codes. As an outcome, the methods developed can help both DNOs and DG developers make sound and practical decisions, facilitating the integration of renewable DG in a more cost-effective way.
7

A concretização do direito financeiro: os efeitos do contingenciamento na execução orçamentária / The achievement of the public finance law: budgetary curtailment effects on the budget execution.

Silveira, Francisco Secaf Alves 01 October 2014 (has links)
O presente trabalho visa investigar em que medida o contingenciamento (artigo 9º da Lei de Responsabilidade Fiscal) tem sido aplicado fora de seus parâmetros jurídicos e, consequentemente, representado um obstáculo à concretização do Direito Financeiro. Por trás desse objetivo está a ideia de que, atualmente, o grande desafio do Direito Constitucional Financeiro é a sua concretização. O trabalho está estruturado em cinco capítulos. No primeiro capítulo, são estabelecidas as premissas: o que se entende por concretização do Direito Constitucional Financeiro e quais são os principais obstáculos para esta. Nessa linha, destaca-se, em primeiro lugar, que o Direito Financeiro está inserido em um novo paradigma, no qual o orçamento deve ser encarado como meio de dar efetividade à Constituição, como instrumento de implementação do Estado Democrático de Direito e dos direitos fundamentais. Em segundo lugar, discute-se a prática relativa aos instrumentos de flexibilização orçamentária e como esta representa, em larga medida, um entrave à concretização do Direito Financeiro. No segundo capítulo, adentra-se na análise do instrumento de flexibilização orçamentária objeto de estudo o contingenciamento , interpretando-se o artigo 9º da Lei de Responsabilidade Fiscal. Delineados os principais aspectos da norma que prevê o contingenciamento, no terceiro capítulo passa-se a olhar para sua aplicação. A partir de uma revisão doutrinária e de um levantamento de dados da execução orçamentária federal dos anos de 2010 a 2013, verifica-se em que medida há uma prática relativa ao contingenciamento fora dos parâmetros jurídicos. O quarto capítulo aponta para os efeitos do contingenciamento na execução do orçamento sob quatro perspectivas: (i) da realização de políticas públicas e consolidação de direitos sociais, (ii) do planejamento, (iii) da transparência e (iv) da legitimidade democrática do gasto público. Por meio dessa análise, além de reforçar as considerações do capítulo anterior, é possível configurar que a prática do contingenciamento tem sido um obstáculo à concretização do Direito Financeiro no Brasil. Por último, no quinto capítulo, apresentaram-se algumas propostas para o controle do contingenciamento no âmbito do Tribunal de Contas, do Poder Legislativo e do Poder Judiciário, verificando-se que é possível um controle jurídico do contingenciamento que, consequentemente, permita uma maior concretização do Direito Financeiro. / The present study aims to investigate if the budgetary curtailment (Article 9 of the Fiscal Responsibility Law) has been applied according to its legal rules and if it represents an obstacle to the achievement of the Brazilian Public Finance Law. The thesis is structured in five chapters. The first chapter establishes two premises: the meaning of achieving the Public Finance Law and the main obstacles for it. We assume that the Public Finance Law is inserted into a new paradigm, in which the budget should be seen as a way to give effectiveness to the Constitution and as an instrument for implementing democratic rules and fundamental rights. We also discuss the practice regarding the flexibility instruments and how they can be an obstacle to the Public Finance Law achievement. In the second chapter, we analyse the budgetary curtailment regulation, specifically the article 9 of the Fiscal Responsibility Law. The third chapter looks to the use of the curtailment in the federal budget execution. From a doctrinal review and from a data collection of 2010-2013 federal budget execution, we demonstrate that there is an illegal use of the curtailments. The fourth chapter points out to the effects of curtailment in budget execution from four perspectives: (i) the accomplishment of public policies, (ii) the budget planning, (iii) the fiscal transparency and (iv) the democratic legitimacy of public expenditure. By this analysis, we conclude that the use of the curtailment in the federal budget execution has been an obstacle to the achievement of the Public Finance Law in Brazil. Finally, the fifth chapter presents some proposals for controlling the budget curtailment within the Federal Court of Accounts, the Legislative and the Judiciary. We verify that it is possible a legal control of the budget curtailment to strengthen the achievement of Public Finance Law.
8

A concretização do direito financeiro: os efeitos do contingenciamento na execução orçamentária / The achievement of the public finance law: budgetary curtailment effects on the budget execution.

Francisco Secaf Alves Silveira 01 October 2014 (has links)
O presente trabalho visa investigar em que medida o contingenciamento (artigo 9º da Lei de Responsabilidade Fiscal) tem sido aplicado fora de seus parâmetros jurídicos e, consequentemente, representado um obstáculo à concretização do Direito Financeiro. Por trás desse objetivo está a ideia de que, atualmente, o grande desafio do Direito Constitucional Financeiro é a sua concretização. O trabalho está estruturado em cinco capítulos. No primeiro capítulo, são estabelecidas as premissas: o que se entende por concretização do Direito Constitucional Financeiro e quais são os principais obstáculos para esta. Nessa linha, destaca-se, em primeiro lugar, que o Direito Financeiro está inserido em um novo paradigma, no qual o orçamento deve ser encarado como meio de dar efetividade à Constituição, como instrumento de implementação do Estado Democrático de Direito e dos direitos fundamentais. Em segundo lugar, discute-se a prática relativa aos instrumentos de flexibilização orçamentária e como esta representa, em larga medida, um entrave à concretização do Direito Financeiro. No segundo capítulo, adentra-se na análise do instrumento de flexibilização orçamentária objeto de estudo o contingenciamento , interpretando-se o artigo 9º da Lei de Responsabilidade Fiscal. Delineados os principais aspectos da norma que prevê o contingenciamento, no terceiro capítulo passa-se a olhar para sua aplicação. A partir de uma revisão doutrinária e de um levantamento de dados da execução orçamentária federal dos anos de 2010 a 2013, verifica-se em que medida há uma prática relativa ao contingenciamento fora dos parâmetros jurídicos. O quarto capítulo aponta para os efeitos do contingenciamento na execução do orçamento sob quatro perspectivas: (i) da realização de políticas públicas e consolidação de direitos sociais, (ii) do planejamento, (iii) da transparência e (iv) da legitimidade democrática do gasto público. Por meio dessa análise, além de reforçar as considerações do capítulo anterior, é possível configurar que a prática do contingenciamento tem sido um obstáculo à concretização do Direito Financeiro no Brasil. Por último, no quinto capítulo, apresentaram-se algumas propostas para o controle do contingenciamento no âmbito do Tribunal de Contas, do Poder Legislativo e do Poder Judiciário, verificando-se que é possível um controle jurídico do contingenciamento que, consequentemente, permita uma maior concretização do Direito Financeiro. / The present study aims to investigate if the budgetary curtailment (Article 9 of the Fiscal Responsibility Law) has been applied according to its legal rules and if it represents an obstacle to the achievement of the Brazilian Public Finance Law. The thesis is structured in five chapters. The first chapter establishes two premises: the meaning of achieving the Public Finance Law and the main obstacles for it. We assume that the Public Finance Law is inserted into a new paradigm, in which the budget should be seen as a way to give effectiveness to the Constitution and as an instrument for implementing democratic rules and fundamental rights. We also discuss the practice regarding the flexibility instruments and how they can be an obstacle to the Public Finance Law achievement. In the second chapter, we analyse the budgetary curtailment regulation, specifically the article 9 of the Fiscal Responsibility Law. The third chapter looks to the use of the curtailment in the federal budget execution. From a doctrinal review and from a data collection of 2010-2013 federal budget execution, we demonstrate that there is an illegal use of the curtailments. The fourth chapter points out to the effects of curtailment in budget execution from four perspectives: (i) the accomplishment of public policies, (ii) the budget planning, (iii) the fiscal transparency and (iv) the democratic legitimacy of public expenditure. By this analysis, we conclude that the use of the curtailment in the federal budget execution has been an obstacle to the achievement of the Public Finance Law in Brazil. Finally, the fifth chapter presents some proposals for controlling the budget curtailment within the Federal Court of Accounts, the Legislative and the Judiciary. We verify that it is possible a legal control of the budget curtailment to strengthen the achievement of Public Finance Law.
9

Incorporating wind power curtailment in reliability and wind energy benefit assessment

2015 June 1900 (has links)
Fossil fuel is presently a major source for electricity production, but it contributes significantly to Green House Gas emissions. Wind is a promising alternative, and can potentially become a major power resource in future power systems. Wind power installations are growing significantly for producing clean energy in electric power systems. As the wind penetration continues to increase to relatively high levels, it can significantly affect the overall performance and reliability of the power system. Hence, it becomes very important to accurately model the behaviour of wind, its interaction with conventional sources and also with other wind resources connected to the power system in order to conduct a realistic assessment of system reliability and benefits from wind energy utilization. When the wind penetration levels are low, all the wind energy generated is utilized to serve the load. However, at higher wind penetration levels, wind energy is spilled due to limitations in the operating reserve or ramping capability of the scheduled generating units. The system reliability and the wind energy benefits are reduced as the wind energy spillage increases due to wind curtailment. Hence, accurate wind models should be researched and developed to include wind energy curtailment in the reliability modelling, considering factors such as the system load level, priority loading order of the generating unit and response rates of the generating units. Researchers have not incorporated these factors in wind power modelling and in the adequacy evaluation of wind integrated power systems. A new analytical technique is developed in the subsequent chapters to carry out a comprehensive wind absorption capability evaluation of the power system, and also to incorporate this characteristic in reliability modelling of the system. Wind curtailments can take place not only due to generation constraints, but also due to transmission line constraints depending on the capacity and location of the wind energy resource in the power system, and the power transfer capacity of the transmission lines connected to the wind farm bus. Therefore, reliability modelling of the power system considering wind curtailments due to both generation and transmission constraints should be carried out to assess the impact of wind farms on bulk system reliability and the wind energy benefits. Wind curtailment is incorporated in the composite power system reliability evaluation by modelling the wind resource both as generation and as negative load. The techniques can be utilized to conduct system adequacy and wind energy benefit assessment both at the capacity planning stages and composite generation/transmission planning stages, incorporating wind power curtailment due to generating unit response limitations. As the wind penetration in a power system increases, the wind farms connected to the system are distributed at different geographical locations. Both analytical and Monte Carlo Simulation based techniques have previously been used by the research group at the University of Saskatchewan to include the cross correlation between the wind characteristics of different wind farms in the wind modelling for reliability evaluation of power systems. However, the combined effect of wind diversity and wind curtailments due to both transmission and generation constraints on the system reliability and wind energy benefit assessment has not been considered. The techniques developed for system adequacy and wind energy benefit assessment considering wind curtailment due to generation and transmission constraints are further modified and presented in this thesis to include wind diversity in the analysis. The developed techniques for adequacy evaluation of wind integrated power systems considering wind power curtailment and diversity should be extremely useful for system planning engineers and policy makers as wind power penetration in power systems continues to increase throughout the world.
10

Intégration des incertitudes liées à la production et à son effacement sur les méthodes de planification des réseaux / Integration of uncertainties related to production and its curtailment on network planning methods

Garry, Aurel 15 September 2016 (has links)
Dans le domaine de la distribution d’électricité, l’arrivée progressive de production décentralisée rend certains réseaux de distribution exportateurs de puissance, au point où des investissements sont nécessaires pour permettre l’évacuation de la puissance produite. La progression de l’instrumentation des réseaux permet au distributeur d’obtenir des informations de plus en plus riches sur la production décentralisée et la question d’intégrer celles-ci dans les procédés de planification français se pose. À partir de relevés de production, on vérifie que les situations de référence utilisées pour dimensionner le réseau présentent un risque d’occurrence suffisant pour nécessiter des investissements. Si des solutions offrant de la flexibilité sont utilisées, celles-ci peuvent être intégrées au processus de planification. Une étude technico-économique est nécessaire et des méthodes sont proposées pour estimer les fréquences de forte production et la dispersion possible pour un ou plusieurs producteurs. Des modèles simples de loi jointe sont proposés. Le cas pratique de l’effacement de production est testé sur des réseaux considérés réalistes. À partir des relevés réels et des modèles, l’effacement est comparé à l’option d’investir au niveau du poste source. Des abaques de décision sont tracés permettant une projection rapide du distributeur. Par ailleurs dans une optique d’utilisation de l’effacement pour gérer des contraintes intra-réseau, une méthode de calcul de load flow probabilisé est proposée ; celle-ci permet d’estimer rapidement la quantité d’effacement requise et de réaliser un comparatif économique entre plusieurs options. / In the field of electricity distribution, some grids are more and more frequently exporters due to the gradual arrival of decentralized generation. Some grid investments are required to allow the evacuation of the power generated. As more and more information about decentralized production are available for the DSO, the question of integrating them into the planning processes arises.From data of energy production, it appears that the current situations tested for sizing the grid are likely to be reached on a several years basis. If consumption or production flexibilities are used, these can be integrated into the planning process. A technical and economic study is needed and methods are proposed to estimate the frequencies of high production and possible dispersion for one or more producers. Simple models of joint distribution are proposed.The practical case of curtailing production has been tested on networks with realistic scenarios of producers arrival. From actual data and previous models, curtailment and reinforcement are compared on a technico-economic basis. A abacus is plotted as a simple decision tool for the DSO. The question of using curtailment to defer or avoid intra-grid investment has also been investigated ; a calculation method of probabilistic load flow is proposed; it gives a quick and accurate estimation of the energy to curtail in order to avoid a constraint.

Page generated in 0.0669 seconds