Página 1 dos resultados de 710 itens digitais encontrados em 0.032 segundos

## Smart meter integrado a analisador de qualidade de energia para propósitos de identificação de cargas residenciais; Smart meter integrated to power quality analyzer for identification purposes of residential loads

Fugita, Sergio Date
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Relevância na Pesquisa
46.01%

## Contribuição à análise do controle de potências ativa e reativa de um gerador de indução com rotor bobinado conectado a uma rede elétrica com tensão distorcida : A contribution to the active and reactive power control analysis of a wound-rotor induction generator connected to a electric grid with distorted voltage; A contribution to the active and reactive power control analysis of a wound-rotor induction generator connected to a electric grid with distorted voltage

Ramon Rodrigues de Souza
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Relevância na Pesquisa
56.14%

## High performance power delivery for nanoscale integrated circuits

Köse, Selçuk ; Friedman, Eby G.
Fonte: University of Rochester Publicador: University of Rochester
Tipo: Tese de Doutorado Formato: Number of Pages:xxiii, 240 leaves; Illustrations:ill. (some col.)
ENG
Relevância na Pesquisa
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Thesis (Ph. D.)--University of Rochester. Dept. of Electrical and Computer Engineering, 2012.; A critical challenge in high performance nanoscale integrated circuits is high quality power delivery. The efficient generation and distribution of multiple on-chip power supply voltages require fundamental changes to the power delivery process to provide increased current in next generation nanoscale integrated circuits. Four primary components are required to realize an efficient power delivery system: (a) ultra-small voltage converters to generate power close to the load, (b) accurate models to characterize the individual power components, (c) efficient algorithms to analyze the quality of the power delivered to the load circuits, and (d) a co-design methodology to simultaneously determine the optimal location of the on-chip power supplies and decoupling capacitors. In this dissertation, a hybrid combination of a switching and low-dropout (LDO) regulator as a point-of-load power supply for next generation heterogeneous systems is proposed. The area of this circuit is significantly smaller than the area of conventional voltage regulators, while maintaining high current efficiency. The proposed circuit provides a means for distributing multiple local power supplies across an integrated circuit. Another important challenge in the realization of effective power delivery systems is the analysis of this highly complicated structure where individual voltage fluctuations at millions of nodes need to be efficiently determined. Closed-form expressions for the effective resistance between circuit components have been developed. This effective resistance model is utilized in the development of a power grid analysis algorithm to compute the node voltages without requiring any iterations. This algorithm drastically improves computational complexity since the iterative procedures to determine IR drop and L di/dt noise are no longer needed. With the introduction of ultra-small on-chip voltage regulators...

## India Power Sector Diagnostic Review : More Power to India - The Challenge of Distribution

World Bank
Fonte: Washington, DC Publicador: Washington, DC
EN_US
Relevância na Pesquisa
46.07%
This report reviews the evolution of the Indian power sector since the landmark Electricity Act of 2003 (EA 2003, or EA), with a focus on distribution as key to performance and viability of the sector. While all three segments of the power sector generation, transmission, and distribution are important, revenues originate with the customer at distribution, so subpar performance there hurts the entire value chain. Persistent operational and financial shortcomings in distribution have repeatedly led to central bailouts for the whole sector, even though power is a concurrent 1 subject under the Indian constitution and distribution is almost entirely under state control. Ominously, the recent sharp increase in private investment and market borrowing means power sector difficulties are more likely to spill over to lenders and affect the broader financial sector. Government-initiated reform efforts first focused on the generation and transmission segments, reflecting the urgent need for adding capacity and the complexity of issues to be addressed at the consumer interface. Consequently...

## Republic of South Sudan : Analysis of Juba Distribution Network and Capacity Building Needs in the Electricity Sector

World Bank
Fonte: Washington, DC Publicador: Washington, DC
EN_US
Relevância na Pesquisa
46.11%
This section of the report aims to provide an analysis and propose specific technical plans for investment in the Juba distribution network to carry out emergency upgrades (as a short term measure) and to enable it to absorb possible power that is foreseen to be delivered from possible increase in supply (such as, through the Fula Rapids HPP). The report firstly explains the current Juba grid status, followed by the approach undertaken by the study. Then, it presents the result of gap analysis, concluding with the distribution investment plan and its necessary measures to achieve the target. It is to be noted that in the medium term, a detailed least cost investment plan (LCIP) for the country (planned under ESTAP) will be developed which will provide comprehensive methodology as well as an assessment of appropriate technical standards to be incorporated in development of the South Sudan electrical grid network.

## Multi-terminal HVDC and power flow analysis

Gil Colmenero, Esther
Tipo: info:eu-repo/semantics/bachelorThesis; info:eu-repo/semantics/masterThesis
ENG
Relevância na Pesquisa
45.99%
The aim of this Specialization Project is to implement and demonstrate a general AC/DC power flow solution in the Matlab environment. This task is interesting from the point of view of the increasing development of the integration of offshore wind power, especially in the North Sea area. The solution proposed in this paper, is valid for systems consisting on one DC grid, each of its buses is connected to different AC grids. Specifically, this study focuses on a general DC grid of three nodes and three consequent AC grids. In this project, a complete procedure on how to set-up the power flow model is developed and described. The first step taken in this process consists on the calculation of the power flows of all the AC grids, in a sequential way. In addition to the calculation of all the involved AC systems, the DC power flow has to be solved as well. The calculations of both power flows, AC and DC, have been implemented using the Newton-Raphson solution algorithm. A key challenge in this procedure has been to model the connection between the AC and DC grid through the HVDC converters. Several possibilities have been studied, mainly depending on the type of bus in question. A study and comparison between a converter with or without losses have been done as well. The final achievements of this Specialization Project consist on a Matlab code solving successfully this matter...

## The Role of Policy Driven Incentives : A Cross-Country Analysis

Vagliasindi, Maria
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Publications & Research :: Policy Research Working Paper; Publications & Research
ENGLISH; EN_US
Relevância na Pesquisa
45.99%
This paper presents new global evidence on the key determinants of public-private partnership investment in electricity generated by renewable energy based on a panel data analysis for 105 developing countries over a period of 16 years from 1993 to 2008. It aims to identify the key factors affecting the private investor's decision to enter renewable-based energy generation, through a probit analysis and the amount of investment sunk in this market segment, based on Heckman's sample selection analysis. One of the key results of the paper is that the market for renewable-based energy is strongly driven by supportive policies. Support policies serve not only to attract the entry of private investors, but also to determine the level of investment. In the latter case, its impact is less significant, suggesting the need over time to revisit the power of the incentive schemes, as well as the implied allocation of risks between the public and private sector to ensure that feed-in tariffs produce the desired amount of investment. In contrast...

## Paying the Price for Unreliable Power Supplies : In-House Generation of Electricity by Firms in Africa

Foster, Vivien; Steinbuks, Jevgenijs
Fonte: Banco Mundial Publicador: Banco Mundial
Tipo: Publications & Research :: Policy Research Working Paper
ENGLISH
Relevância na Pesquisa
45.99%
This paper documents the prevalence of in-house generation of electric power by firms in Sub-Saharan Africa and attempts to identify the underlying causes. The analysis is based on two data sources. The UDI World Electric Power Plants Data Base (WEPP), a global inventory of electric power generating units, provides a detailed inventory of in-house generation at the country level. The World Bank's Enterprise Survey Database captures business perceptions of the obstacles to enterprise growth for 8,483 currently operating firms in 25 African countries. Overall, so-called own generation by firms-which has been on the rise in recent years-accounts for about 6 percent of installed generation capacity in Sub-Saharan Africa (equivalent to at least 4,000 MW of installed capacity). However, this share doubles to around 12 percent in the low-income countries, the post-conflict countries, and more generally on the Western side of the continent. In a handful of countries own generation represents more than 20 percent of capacity. Rigorous empirical analysis shows that unreliable public power supplies is far from being the only or even the largest factor driving generator ownership. Firm characteristics have a major influence-in particular...

## Surge in Solar-Powered Homes : Experience in Off-Grid Rural Bangladesh

Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Publications & Research :: Publication; Publications & Research :: Publication
ENGLISH
Relevância na Pesquisa
46.12%
Bangladesh has made remarkable progress in raising living standards and reducing poverty, particularly in previously lagging regions. Rapid solar home system (SHS) expansion in Bangladesh to some 3 million rural households by early 2014 has drawn the attention of donors and governments of other countries. The book s broad aim is twofold: (a) to assess the welfare impact of SHS on households, and (b) to evaluate the present institutional structure and financing mechanisms in place, noting that households want cheaper systems and good quality service while suppliers require a reasonable market-based profit to stay in business. The study entailed an intensive empirical investigation based on both primary and secondary data. The primary data consisted mainly of a large-scale, nationally representative household survey with appropriate geographic spread. Conducted in 2012 by the Bangladesh Institute of Development Studies (BIDS) and assisted by the World Bank, the household survey was designed to examine SHS benefits and costs. The book addresses a number of research issues...

## Multifunctional converter to interface renewable energy sources and electric vehicles with the power grid in smart grids context

Monteiro, Vítor; Pinto, J. G.; Exposto, Bruno Fernandes; Pedrosa, Delfim; Afonso, João L.
Tipo: Conferência ou Objeto de Conferência
Relevância na Pesquisa
56.1%
This paper proposes a multifunctional converter to interface renewable energy sources (e.g., solar photovoltaic panels) and electric vehicles (EVs) with the power grid in smart grids context. This multifunctional converter allows deliver energy from the solar photovoltaic panels to an EV or to the power grid, and exchange energy in bidirectional mode between the EV and the power grid. Using this multifunctional converter are not required multiple conversion stages, as occurs with the traditional solutions, where are necessary two power converters to integrate the solar photovoltaic system in the power grid and also two power converters to integrate an off-board EV battery charger in the power grid (dc-dc and dc-ac power converters in both cases). Taking into account that the energy provided (or delivered) from the power grid in each moment is function of the EV operation mode and also of the energy produced from the solar photovoltaic system, it is possible to define operation strategies and control algorithms in order to increase the energy efficiency of the global system and to improve the power quality of the electrical system. The proposed multifunctional converter allows the operation in four distinct cases: (a) Transfer of energy from the solar photovoltaic system to the power grid; (b) Transfer of energy from the solar photovoltaic system and from the EV to the power grid; (c) Transfer of energy from the solar photovoltaic system to the EV or to the power grid; (d) Transfer of energy between the EV and the power grid. Along the paper are described the system architecture and the control algorithms...

## Power Grid Defense Against Malicious Cascading Failure

Shakarian, Paulo; Lei, Hansheng; Lindelauf, Roy
Tipo: Artigo de Revista Científica
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An adversary looking to disrupt a power grid may look to target certain substations and sources of power generation to initiate a cascading failure that maximizes the number of customers without electricity. This is particularly an important concern when the enemy has the capability to launch cyber-attacks as practical concerns (i.e. avoiding disruption of service, presence of legacy systems, etc.) may hinder security. Hence, a defender can harden the security posture at certain power stations but may lack the time and resources to do this for the entire power grid. We model a power grid as a graph and introduce the cascading failure game in which both the defender and attacker choose a subset of power stations such as to minimize (maximize) the number of consumers having access to producers of power. We formalize problems for identifying both mixed and deterministic strategies for both players, prove complexity results under a variety of different scenarios, identify tractable cases, and develop algorithms for these problems. We also perform an experimental evaluation of the model and game on a real-world power grid network. Empirically, we noted that the game favors the attacker as he benefits more from increased resources than the defender. Further...

## Power Grid Simulation using Matrix Exponential Method with Rational Krylov Subspaces

Zhuang, Hao; Weng, Shih-Hung; Cheng, Chung-Kuan
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
56.01%
One well adopted power grid simulation methodology is to factorize matrix once and perform only backward forward substitution with a deliberately chosen step size along the simulation. Since the required simulation time is usually long for the power grid design, the costly factorization is amortized. However, such fixed step size cannot exploit larger step size for the low frequency response in the power grid to speedup the simulation. In this work, we utilize the matrix exponential method with the rational Krylov subspace approximation to enable adaptive step size in the power grid simulation. The kernel operation in our method only demands one factorization and backward forward substitutions. Moreover, the rational Krylov subspace approximation can relax the stiffness constraint of the previous works. The cheap computation of adaptivity in our method could exploit the long low frequency response in a power grid and significantly accelerate the simulation. The experimental results show that our method achieves up to 18X speedup over the trapezoidal method with fixed step size.

## Topological Analysis and Mitigation Strategies for Cascading Failures in Power Grid Networks

Pahwa, Sakshi; Scoglio, Caterina; Schulz, Noel
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46%
Recently, there has been a growing concern about the overload status of the power grid networks, and the increasing possibility of cascading failures. Many researchers have studied these networks to provide design guidelines for more robust power grids. Topological analysis is one of the components of system analysis for its robustness. This paper presents a complex systems analysis of power grid networks. First, the cascading effect has been simulated on three well known networks: the IEEE 300 bus test system, the IEEE 118 bus test system, and the WSCC 179 bus equivalent model. To extend the analysis to a larger set of networks, we develop a network generator and generate multiple graphs with characteristics similar to the IEEE test networks but with different topologies. The generated graphs are then compared to the test networks to show the effect of topology in determining their robustness with respect to cascading failures. The generated graphs turn out to be more robust than the test graphs, showing the importance of topology in the robust design of power grids. The second part of this paper concerns the discussion of two novel mitigation strategies for cascading failures: Targeted Load Reduction and Islanding using Distributed Sources. These new mitigation strategies are compared with the Homogeneous Load Reduction strategy. Even though the Homogeneous Load Reduction is simpler to implement...

## Power Grid Vulnerability to Geographically Correlated Failures - Analysis and Control Implications

Bernstein, Andrey; Bienstock, Daniel; Hay, David; Uzunoglu, Meric; Zussman, Gil
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.04%

## An Efficient Topology-Based Algorithm for Transient Analysis of Power Grid

Wang, Jim Jing-Yan; Yang, Lan; Wang, Jingbin; Azevedo, Lorenzo
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
56.01%
In the design flow of integrated circuits, chip-level verification is an important step that sanity checks the performance is as expected. Power grid verification is one of the most expensive and time-consuming steps of chip-level verification, due to its extremely large size. Efficient power grid analysis technology is highly demanded as it saves computing resources and enables faster iteration. In this paper, a topology-base power grid transient analysis algorithm is proposed. Nodal analysis is adopted to analyze the topology which is mathematically equivalent to iteratively solving a positive semi-definite linear equation. The convergence of the method is proved.

## Message Passing for Integrating and Assessing Renewable Generation in a Redundant Power Grid

Zdeborová, Lenka; Backhaus, Scott; Chertkov, Michael
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
55.88%
A simplified model of a redundant power grid is used to study integration of fluctuating renewable generation. The grid consists of large number of generator and consumer nodes. The net power consumption is determined by the difference between the gross consumption and the level of renewable generation. The gross consumption is drawn from a narrow distribution representing the predictability of aggregated loads, and we consider two different distributions representing wind and solar resources. Each generator is connected to D consumers, and redundancy is built in by connecting R of these consumers to other generators. The lines are switchable so that at any instance each consumer is connected to a single generator. We explore the capacity of the renewable generation by determining the level of "firm" generation capacity that can be displaced for different levels of redundancy R. We also develop message-passing control algorithm for finding switch settings where no generator is overloaded.; Comment: 10 pages, accepted for HICSS-43

## Smoothing effect for spatially distributed renewable resources and its impact on power grid robustness

Nagata, Motoki; Hirata, Yoshito; Fujiwara, Naoya; Tanaka, Gouhei; Suzuki, Hideyuki; Aihara, Kazuyuki
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
56.01%
In this paper, we show that spatial correlation of renewable energy outputs greatly influences the robustness of power grids. First, we propose a new index for the spatial correlation among renewable energy outputs. We find that the spatial correlation of renewable energy outputs in a short time-scale is as weak as that caused by independent random variables and that in a long time-scale is as strong as that under perfect synchronization. Then, by employing the topology of the power grid in eastern Japan, we analyze the robustness of the power grid with spatial correlation of renewable energy outputs. The analysis is performed by using a realistic differential-algebraic equations model and the result shows that the spatial correlation of the energy resources strongly degrades the robustness of the power grid. Our result suggests that the spatial correlation of the renewable energy outputs should be taken into account when estimating the stability of power grids.

## Stochastic Power Grid Analysis Considering Process Variations

Ghanta, Praveen; Vrudhula, Sarma; Panda, Rajendran; Wang, Janet
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
66%
In this paper, we investigate the impact of interconnect and device process variations on voltage fluctuations in power grids. We consider random variations in the power grid's electrical parameters as spatial stochastic processes and propose a new and efficient method to compute the stochastic voltage response of the power grid. Our approach provides an explicit analytical representation of the stochastic voltage response using orthogonal polynomials in a Hilbert space. The approach has been implemented in a prototype software called OPERA (Orthogonal Polynomial Expansions for Response Analysis). Use of OPERA on industrial power grids demonstrated speed-ups of up to two orders of magnitude. The results also show a significant variation of about $\pm$ 35% in the nominal voltage drops at various nodes of the power grids and demonstrate the need for variation-aware power grid analysis.; Comment: Submitted on behalf of EDAA (http://www.edaa.com/)

## Comparative analysis of existing models for power-grid synchronization

Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.07%
The dynamics of power-grid networks is becoming an increasingly active area of research within the physics and network science communities. The results from such studies are typically insightful and illustrative, but are often based on simplifying assumptions that can be either difficult to assess or not fully justified for realistic applications. Here we perform a comprehensive comparative analysis of three leading models recently used to study synchronization dynamics in power-grid networks -- a fundamental problem of practical significance given that frequency synchronization of all power generators in the same interconnection is a necessary condition for a power grid to operate. We show that each of these models can be derived from first principles within a common framework based on the classical model of a generator, thereby clarifying all assumptions involved. This framework allows us to view power grids as complex networks of coupled second-order phase oscillators with both forcing and damping terms. Using simple illustrative examples, test systems, and real power-grid datasets, we study the inherent frequencies of the oscillators as well as their coupling structure, comparing across the different models. We demonstrate, in particular...

## Evaluation of the Photovoltaic System Installation Impact to an Electric Power Grid Part 1: Simulation of photovoltaic generation by applying a meteorological model; Evaluation of the Photovoltaic System Installation Impact to an Electric Power Grid. Part 1: Simulation of photovoltaic generation by applying a meteorological model; ; ;

Wyss Porras, Juan Ernesto; Shimada, Sususmu; Yoshino, Jun; Kobayashi, Tomonao
Fonte: Labor & Engenho; Labor & Engenho Publicador: Labor & Engenho; Labor & Engenho
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Artigo Avaliado pelos Pares Formato: application/pdf