Okumura, Teppei; More, Surhud; Masaki, Shogo
2016-01-01
The peculiar velocity field measured by redshift-space distortions (RSD) in galaxy surveys provides a unique probe of the growth of large-scale structure. However, systematic effects arise when including satellite galaxies in the clustering analysis. Since satellite galaxies tend to reside in massive halos with a greater halo bias, the inclusion boosts the clustering power. In addition, virial motions of the satellite galaxies cause a significant suppression of the clustering power due to nonlinear RSD effects. We develop a novel method to recover the redshift-space power spectrum of halos from the observed galaxy distribution by minimizing the contamination of satellite galaxies. The cylinder grouping method (CGM) we study effectively excludes satellite galaxies from a galaxy sample. However, we find that this technique produces apparent anisotropies in the reconstructed halo distribution over all the scales which mimic RSD. On small scales, the apparent anisotropic clustering is caused by exclusion of halos...
Directory of Open Access Journals (Sweden)
Cheng Jia-xu
2016-01-01
Full Text Available In order to solve the problem of exist in W company salary distribution, such as the work guide is unknown, incentive enough, the target set properly and other issues, this paper especially focuses on the characteristics of enterprises, the company management and control model and other aspects to do in-depth study. On the basis of recognition control mode the pay distribution structure is determined, and then the appropriate indicators are sated. They are linked to further clarify the distribution of the guide, while the target value of properly designed and incentive mechanisms to ensure that the salary distribution model to follow on the basis of the relevant principles on the realization of economic promotion and to promote the strategic objectives.
Energy Technology Data Exchange (ETDEWEB)
NONE
2000-06-01
Facing the new law on the electric power market liberalization, the french government created an experts group to analyze solutions and assessment methods of the electrical networks costs and tariffs and to control their efficiency. This report presents the analysis and the conclusions of the group. It concerns the three main subjects: the regulation context, the tariffing of the electric power transmission and distribution (the cost and efficiency of the various options) and the tariffing of the electric power supply to the eligible consumers. The authors provide a guideline for a tariffing policy. (A.L.B.)
Energy Technology Data Exchange (ETDEWEB)
NONE
2000-06-01
Facing the new law on the electric power market liberalization, the french government created an experts group to analyze solutions and assessment methods of the electrical networks costs and tariffs and to control their efficiency. This report presents the analysis and the conclusions of the group. It concerns the three main subjects: the regulation context, the tariffing of the electric power transmission and distribution (the cost and efficiency of the various options) and the tariffing of the electric power supply to the eligible consumers. The authors provide a guideline for a tariffing policy. (A.L.B.)
Parton Distributions Working Group
Energy Technology Data Exchange (ETDEWEB)
de Barbaro, L.; Keller, S. A.; Kuhlmann, S.; Schellman, H.; Tung, W.-K.
2000-07-20
This report summarizes the activities of the Parton Distributions Working Group of the QCD and Weak Boson Physics workshop held in preparation for Run II at the Fermilab Tevatron. The main focus of this working group was to investigate the different issues associated with the development of quantitative tools to estimate parton distribution functions uncertainties. In the conclusion, the authors introduce a Manifesto that describes an optimal method for reporting data.
Power distribution arrangement
DEFF Research Database (Denmark)
2010-01-01
An arrangement and a method for distributing power supplied by a power source to two or more of loads (e.g., electrical vehicular systems) is disclosed, where a representation of the power taken by a particular one of the loads from the source is measured. The measured representation of the amount...
Electric power distribution handbook
Short, Thomas Allen
2003-01-01
Of the ...big three... components of the electricity infrastructure, distribution typically gets the least attention, and no thorough, up-to-date treatment of the subject has been published in years. Filling that void, the Electric Power Distribution Handbook provides comprehensive information on the electrical aspects of power distribution systems. It is an unparalleled source for the background information, hard-to-find tables, graphs, methods, and statistics that power engineers need, and includes tips and solutions for problem solving and improving performance. In short, this handbook giv
Parton Distributions Working Group
de Barbaro, Lucy; Brock, R.; Casey, D.; Demina, R.; Giele, W.T.; Hirosky, R.; Huston, J.; Kalk, J.; Keller, S.A.; Klasen, M.; Kosower, D.A.; Kramer, M.; Kretzer, S.; Kuhlmann, S.; Martin, R.; Olness, Fredrick I.; Plehn, T.; Pumplin, J.; Scalise, R.J.; Schellman, H.; Smith, J.; Soper, D.E.; Sterman, George F.; Stump, D.; Tung, W.K.; Varelas, N.; Vogelsang, W.; Yang, Un-Ki
2000-01-01
The main focus of this working group was to investigate the different issues associated with the development of quantitative tools to estimate parton distribution functions uncertainties. In the conclusion, we introduce a "Manifesto" that describes an optimal method for reporting data.
Electric power distribution handbook
Short, Thomas Allen
2014-01-01
Of the ""big three"" components of electrical infrastructure, distribution typically gets the least attention. In fact, a thorough, up-to-date treatment of the subject hasn't been published in years, yet deregulation and technical changes have increased the need for better information. Filling this void, the Electric Power Distribution Handbook delivers comprehensive, cutting-edge coverage of the electrical aspects of power distribution systems. The first few chapters of this pragmatic guidebook focus on equipment-oriented information and applications such as choosing transformer connections,
Integrated Groups and Smooth Distribution Groups
Institute of Scientific and Technical Information of China (English)
Pedro J. MIANA
2007-01-01
In this paper, we prove directly that α-times integrated groups define algebra homo-morphisms. We also give a theorem of equivalence between smooth distribution groups and α-times integrated groups.
Distributed Power Flow Controller
Yuan, Z.
2010-01-01
In modern power systems, there is a great demand to control the power flow actively. Power flow controlling devices (PFCDs) are required for such purpose, because the power flow over the lines is the nature result of the impedance of each line. Due to the control capabilities of different types of P
Distributed Power Flow Controller
Yuan, Z.
2010-01-01
In modern power systems, there is a great demand to control the power flow actively. Power flow controlling devices (PFCDs) are required for such purpose, because the power flow over the lines is the nature result of the impedance of each line. Due to the control capabilities of different types of P
Power Aware Distributed Systems
2004-01-01
algorithm from the Army Research Laboratory for power aware analysis. In addition to the algorithm in MATLAB (and ported to C by MIT), the...tool for software energy pro ling”, in Proc. IEEE/ACM DAC, June, 2001. [37] J. L. W. V. Jensen, “Sur les fonctions convexes et les ingalits entre les... fonctions convexes et les ingalits entre les valeurs moyennes”, Acta Math., vol. 30, pp. 175–193, 1906. [37] PARSEC parallel simulation language (http://pcl.cs.ucla.edu/projects/parsec) 19 225
Inhomogeneous Power Distribution in Magnetic Oscillations
Jain, Kiran; Kholikov, S; Hill, F
2010-01-01
We apply ring-diagram analysis and spherical harmonic decomposition methods to compute 3-dimensional power spectra of magnetograms obtained by the Global Oscillation Network Group (GONG) during quiet periods of solar activity. This allows us to investigate the power distribution in acoustic waves propagating in localized directions on the solar disk. We find evidence of the presence of five-minute oscillations in magnetic signals that suggests a non-homogeneous distribution of acoustic power. In this paper, we present our results on the asymmetry in oscillatory power and its behaviour as a function of frequency, time and magnetic field strength. These characteristics are compared with simultaneous velocity measurements.
Leadership behaviours that foster nursing group power.
Sieloff, Christina Leibold
2004-07-01
Today's health care environment presents many challenges to nursing groups as they seek to achieve their goals. All resources must be recognized and effectively utilized. Power, defined as the capacity to achieve goals (Sieloff 1995), is a valuable resource that can assist nursing groups in the achievement of their goals. The leader of a nursing group can make a significant difference in a group's ability to actualize their power capacity. The purpose of this article is to identify and discuss the use of a tool (Sieloff-King Assessment of Group Power within Organizations) to identify the nurse leader/group power variables that can be used to improve a nursing group's power as a resource in the achievement of its goals. Using behaviours related to a Nurse Leader's Power Competency and Power Perspective variables, identified in the Theory of Group Power within Organizations (Sieloff 1999), a nurse leader can foster a nursing group's power.
Electric power distribution, automation, protection, and control
Momoh, James A
2007-01-01
* Each Chapter Provides an Introduction, Illustrative Examples, and a SummaryIntroduction to Distribution Automation Systems Historical Background Distribution System Topology and Structure Distribution Automation (DA) and Control Computational Techniques for Distribution Systems Complex Power Concepts Balanced Voltage to Neutral-Connected System Power Relationship for f Y-?-Connected System Per-Unit System Calculation of Power Losses Voltage Regulation Techniques Voltage-Sag Analysis and Calculation Equipment Modeling Components Modeling Distribution System Line Model Distribution Power Flo
Emergent Power Hierarchies and Group Performance.
Frauendorfer, Denise; Schmid Mast, Marianne; Sanchez-Cortes, Dairazalia; Gatica-Perez, Daniel
2015-10-01
In newly formed groups, informal hierarchies emerge automatically and readily. In this study, we argue that emergent group hierarchies enhance group performance (Hypothesis 1) and we assume that the more the power hierarchy within a group corresponds to the task-competence differences of the individual group members, the better the group performs (Hypothesis 2). Twelve three-person groups and 28 four-person groups were investigated while solving the Winter Survival Task. Results show that emerging power hierarchies positively impact group performance but the alignment between task-competence and power hierarchy did not affect group performance. Thus, emergent power hierarchies are beneficial for group performance and although they were on average created around individual group members' competence, this correspondence was not a prerequisite for better group performance.
Electrical Power Working Group report
Vanommering, Gerrit; Myers, Ira T.
1986-01-01
The status of and need for power technologies for Spacecraft 2000 were assessed and development programs required to establish an achievable and competitive technology base for spacecraft of the 21st century were identified. The results are summarized, including the recommendations and the underlying rationale.
Management Innovations in Power Generation Groups
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
@@ Since the institutional reform of power industry in 2002,power sectors,in particularelectrity generation enterprises in China have been grently changed, not only in institutionand industrial pattern but also in operational environment.The year2006is a turning point of tense power supply lasting for three years and a half .The change of power supply situationin the 11th Five-Year Plan period and in-depth reform of power institutional systm haveplaced serious challenges in front of power genration groups.In this new historical era,powergeneration groups can keep undefeated only by carrying out actively mangement innovations.
Interagency Advanced Power Group meeting minutes
Energy Technology Data Exchange (ETDEWEB)
1991-01-01
This document contains the minutes and viewgraphs from a meeting of military personnel on the subject of power generation and distribution systems for military applications. Topics include heating and cooling systems for standard shelters, SDIO power programs, solar dynamic space power systems, hybrid solar dynamic/ photovoltaic systems, pulsed power technology, high-{Tc} superconductors, and actuators and other electronic equipment for aerospace vehicles. Attendees represented the US Air Force, Army, Navy, and NASA. (GHH)
Interagency Advanced Power Group meeting minutes
Energy Technology Data Exchange (ETDEWEB)
1991-12-31
This document contains the minutes and viewgraphs from a meeting of military personnel on the subject of power generation and distribution systems for military applications. Topics include heating and cooling systems for standard shelters, SDIO power programs, solar dynamic space power systems, hybrid solar dynamic/ photovoltaic systems, pulsed power technology, high-{Tc} superconductors, and actuators and other electronic equipment for aerospace vehicles. Attendees represented the US Air Force, Army, Navy, and NASA. (GHH)
Interagency Advanced Power Group -- Steering group meeting minutes
Energy Technology Data Exchange (ETDEWEB)
1993-11-18
This document contains the draft meeting minutes of the Steering Group of the Interagency Advanced Power Group. Included are the discussions resulting from the presentation of working group reports and the results of a discussion of IAPG policies and procedures. In the appendix are the reports of the following working groups: Electrical, Mechanical, Solar, and Systems.
Power Quality in DC Power Distribution Systems and Microgrids
Directory of Open Access Journals (Sweden)
Stephen Whaite
2015-05-01
Full Text Available This review paper discusses power quality considerations for direct current (DC electric power distribution systems, particularly DC microgrids. First, four selected sample DC architectures are discussed to provide motivation for the consideration of power quality in DC systems. Second, a brief overview of power quality challenges in conventional alternating current (AC distribution systems is given to establish the field of power quality. Finally, a survey of literature addressing power quality issues in DC systems is presented, and necessary power quality considerations in DC distribution system design and operation are discussed.
Wind Power in Electrical Distribution Systems
DEFF Research Database (Denmark)
Chen, Zhe
2013-01-01
as distributed generators in distribution systems. This paper discusses the issues of wind turbines in distribution systems. Wind power conversion systems briefly introduced, the basic features and technical characteristics of distributed wind power system are described, and the main technical demands......Recent years, wind power is experiencing a rapid growth, large number of wind turbines/wind farms have been installed and connected to power systems. In addition to the large centralised wind farms connected to transmission grids, many distributed wind turbines and wind farms are operated...
Distributed power generation using microturbines
CSIR Research Space (South Africa)
Szewczuk, S
2008-11-01
Full Text Available At present, the bulk of the world is electricity is generated in central power stations. This approach, one of `economy of size generates electricity in large power stations and delivers it to load centres via an extensive network of transmission...
Finite Groups with Its Power Automorphism Groups Having Small Indices
Institute of Scientific and Technical Information of China (English)
Jun Xin WANG; Xiu Yun GUO
2009-01-01
In this paper,a finite group G with|Aut(G) : P(G)| = p or pq is determined,where P(G)is the power automorphism group of G,and p,q are distinct primes.Especially,we prove that a finite group G satisfies |Aut(G) : P(G)| = pq if and only if Aut(G)/P(G) (≈)S3.Also,some other classes of finite groups are investigated and classified,which are necessary for the proof of our main results.
Converters for Distributed Power Generation Systems
DEFF Research Database (Denmark)
Blaabjerg, Frede; Yang, Yongheng
2015-01-01
Power electronics technology has become the enabling technology for the integration of distributed power generation systems (DPGS) such as offshore wind turbine power systems and commercial photovoltaic power plants. Depending on the applications, a vast array of DPGS-based power converter...... presents an overview of the power converters for the DPGS, mainly based on wind turbine systems and photovoltaic systems, covering a wide range of applications. Moreover, the modulation schemes and interfacing power filters for the power converters are also exemplified. Finally, the general control...... topologies has been developed and more are coming into the market in order to achieve an efficient and reliable power conversion from the renewables. In addition, stringent demands from both the distribution system operators and the consumers have been imposed on the renewable-based DPGS. This article...
RELIABILITY ANALYSIS OF POWER DISTRIBUTION SYSTEMS
Directory of Open Access Journals (Sweden)
Popescu V.S.
2012-04-01
Full Text Available Power distribution systems are basic parts of power systems and reliability of these systems at present is a key issue for power engineering development and requires special attention. Operation of distribution systems is accompanied by a number of factors that produce random data a large number of unplanned interruptions. Research has shown that the predominant factors that have a significant influence on the reliability of distribution systems are: weather conditions (39.7%, defects in equipment(25% and unknown random factors (20.1%. In the article is studied the influence of random behavior and are presented estimations of reliability of predominantly rural electrical distribution systems.
Power laws, Pareto distributions and Zipf's law
Newman, M E J
2004-01-01
When the probability of measuring a particular value of some quantity varies inversely as a power of that value, the quantity is said to follow a power law, also known variously as Zipf's law or the Pareto distribution. Power laws appear widely in physics, biology, earth and planetary sciences, economics and finance, computer science, demography and the social sciences. For instance, the distributions of the sizes of cities, earthquakes, solar flares, moon craters, wars and people's personal ...
A Grouping Method of Distribution Substations Using Cluster Analysis
Ohtaka, Toshiya; Iwamoto, Shinichi
Recently, it has been considered to group distribution substations together for evaluating the reinforcement planning of distribution systems. However, the grouping is carried out by the knowledge and experience of an expert who is in charge of distribution systems, and a subjective feeling of a human being causes ambiguous grouping at the moment. Therefore, a method for imitating the grouping by the expert has been desired in order to carry out a systematic grouping which has numerical corroboration. In this paper, we propose a grouping method of distribution substations using cluster analysis based on the interconnected power between the distribution substations. Moreover, we consider the geographical constraints such as rivers, roads, business office boundaries and branch boundaries, and also examine a method for adjusting the interconnected power. Simulations are carried out to verify the validity of the proposed method using an example system. From the simulation results, we can find that the imitation of the grouping by the expert becomes possible due to considering the geographical constraints and adjusting the interconnected power, and also the calculation time and iterations can be greatly reduced by introducing the local and tabu search methods.
Electromechanical Peak Devices of Distributed Power Generation
Directory of Open Access Journals (Sweden)
S. V. Konstantinova
2011-01-01
Full Text Available The power world crises (1973, 1979 have demonstrated that mankind entered the expensive energy epoch. More and more attitude is given to power saving problem by including renewable power sources in energy balance of the countries. The paper analyzes a power system inBelarusand a typical chart of the active load is cited in the paper. Equalization of load chart is considered as one of measures directed on provision of higher operational efficiency of power system and power saving. This purpose can be obtained while including electromechanical peak devices of the distributed generation in the energy balance.
Power Electronics Control of Wind Energy in Distributed Power System
DEFF Research Database (Denmark)
Iov, Florin; Ciobotaru, Mihai; Blaabjerg, Frede
2008-01-01
is to change the electrical power production sources from the conventional, fossil (and short term) based energy sources to renewable energy resources. The other is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss the most...... emerging renewable energy sources, wind energy, which by means of power electronics are changing from being a minor energy source to be acting as an important power source in the energy system. Power electronics is the enabling technology and the presentation will cover the development in wind turbine...... technology from kW to MW, discuss which power electronic solutions are most feasible and used today....
Distribution-Agnostic Stochastic Optimal Power Flow for Distribution Grids
Energy Technology Data Exchange (ETDEWEB)
Baker, Kyri; Dall' Anese, Emiliano; Summers, Tyler
2016-11-21
This paper outlines a data-driven, distributionally robust approach to solve chance-constrained AC optimal power flow problems in distribution networks. Uncertain forecasts for loads and power generated by photovoltaic (PV) systems are considered, with the goal of minimizing PV curtailment while meeting power flow and voltage regulation constraints. A data- driven approach is utilized to develop a distributionally robust conservative convex approximation of the chance-constraints; particularly, the mean and covariance matrix of the forecast errors are updated online, and leveraged to enforce voltage regulation with predetermined probability via Chebyshev-based bounds. By combining an accurate linear approximation of the AC power flow equations with the distributionally robust chance constraint reformulation, the resulting optimization problem becomes convex and computationally tractable.
Wind Power in Electrical Distribution Systems
DEFF Research Database (Denmark)
Chen, Zhe
2013-01-01
Recent years, wind power is experiencing a rapid growth, large number of wind turbines/wind farms have been installed and connected to power systems. In addition to the large centralised wind farms connected to transmission grids, many distributed wind turbines and wind farms are operated as dist...
Expert System Detects Power-Distribution Faults
Walters, Jerry L.; Quinn, Todd M.
1994-01-01
Autonomous Power Expert (APEX) computer program is prototype expert-system program detecting faults in electrical-power-distribution system. Assists human operators in diagnosing faults and deciding what adjustments or repairs needed for immediate recovery from faults or for maintenance to correct initially nonthreatening conditions that could develop into faults. Written in Lisp.
Cathode power distribution system and method of using the same for power distribution
Williamson, Mark A; Wiedmeyer, Stanley G; Koehl, Eugene R; Bailey, James L; Willit, James L; Barnes, Laurel A; Blaskovitz, Robert J
2014-11-11
Embodiments include a cathode power distribution system and/or method of using the same for power distribution. The cathode power distribution system includes a plurality of cathode assemblies. Each cathode assembly of the plurality of cathode assemblies includes a plurality of cathode rods. The system also includes a plurality of bus bars configured to distribute current to each of the plurality of cathode assemblies. The plurality of bus bars include a first bus bar configured to distribute the current to first ends of the plurality of cathode assemblies and a second bus bar configured to distribute the current to second ends of the plurality of cathode assemblies.
Power Quality Improvement of a Distributed Generation Power System
Directory of Open Access Journals (Sweden)
Panga Harish
2016-06-01
Full Text Available The aim of this work is to improve the power quality for Distributed Generation (DG with power storage system. Power quality is the combination of voltage quality and current quality. Power quality is the set of limits of electrical properties that allows electrical systems to function in their intended manner without significant loss of performance or life. The electrical power quality is more concerned issue. The main problems are stationery and transient distortions in the line voltage such as harmonics, flicker, swells, sags and voltage asymmetries. Distributed Generation (DG also called as site generation, dispersed generation, embedded generation, decentralized generation, decentralized energy or distributed energy, generates electricity from the many small energy sources. In recent years, micro electric power systems such as photovoltaic generation systems, wind generators and micro gas turbines, etc., have increased with the deregulation and liberalization of the power market. Under such circumstances the environment surrounding the electric power industry has become ever more complicated and provides high-quality power in a stable manner which becomes an important topic. Here DG is assumed to include Wind power Generation (WG and Fuel Cells (FC, etc. Advantages of this system are constant power supply, constant voltage magnitude, absence of harmonics insupply voltage, un-interrupted power supply. In this project the electric power qualities in two cases will be compared. Case I: With the storage battery when it is introduced. Case II: Without the storage battery. The storage battery executes the control that maintains the voltage in the power system. It will be found that the Electric power quality will be improved, when storage battery is introduced. The model system used in this Project work is composed of a Wind Turbine, an Induction Generator, Fuel Cells, An Inverter and a Storage Battery. A miniature Wind Power Generator is
Grid-connected distributed solar power systems
Moyle, R.; Chernoff, H.; Schweizer, T.
This paper discusses some important, though often ignored, technical and economic issues of distributed solar power systems: protection of the utility system and nonsolar customers requires suitable interfaced equipment. Purchase criteria must mirror reality; most analyses use life-cycle costing with low discount rates - most buyers use short payback periods. Distributing, installing, and marketing small, distributed solar systems is more costly than most analyses estimate. Results show that certain local conditions and uncommon purchase considerations can combine to make small, distributed solar power attractive, but lower interconnect costs (per kW), lower marketing and product distribution costs, and more favorable purchase criteria make large, centralized solar energy more attractive. Specifically, the value of dispersed solar systems to investors and utilities can be higher than $2000/kw. However, typical residential owners place a value of well under $1000 on the installed system.
Kamans, Elanor; Otten, Sabine; Gordijn, Ernestine H.; Spears, Russell
2010-01-01
The aim of the current study was to show that the type of conflict behavior (constructive vs. unconstructive) groups use in conflicts depends on their power position as well as the likelihood that power determines victory and defeat. In an alleged online debate, we created a conflict between two opi
Power-law distributions in empirical data
Clauset, Aaron; Newman, M E J
2007-01-01
Power-law distributions occur in many situations of scientific interest and have significant consequences for our understanding of natural and man-made phenomena. Unfortunately, the empirical detection and characterization of power laws is made difficult by the large fluctuations that occur in the tail of the distribution. In particular, standard methods such as least-squares fitting are known to produce systematically biased estimates of parameters for power-law distributions and should not be used in most circumstances. Here we describe statistical techniques for making accurate parameter estimates for power-law data, based on maximum likelihood methods and the Kolmogorov-Smirnov statistic. We also show how to tell whether the data follow a power-law distribution at all, defining quantitative measures that indicate when the power law is a reasonable fit to the data and when it is not. We demonstrate these methods by applying them to twenty-four real-world data sets from a range of different disciplines. Eac...
Distributed generation and centralized power system in Thailand
DEFF Research Database (Denmark)
Sukkumnoed, Decharut
The paper examines and discusses conflicts between the development of distributed power and centralized power system in Thailand.......The paper examines and discusses conflicts between the development of distributed power and centralized power system in Thailand....
Distributed generation and centralized power system in Thailand
DEFF Research Database (Denmark)
Sukkumnoed, Decharut
2004-01-01
The paper examines and discusses conflicts between the development of distributed power and centralized power system.......The paper examines and discusses conflicts between the development of distributed power and centralized power system....
Fully Distributed Cooperative Motion of Group Robots
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
This paper is focused on the fully distributed cooperative motion of group robots and proposes a new approach. Each robot has a local sensing ability and a simple action selection strategy. Computational complexity is decreased by the fully distributed architecture and the information insufficiency is solved by the interaction between the robots and the environment. Variable loop and random method are used to deal with the fluctuation and equity selection problem and the rapidity and reasonabiliiy are guaranteed. Some simulations have proved the effectiveness of the proposed approach.
A mechanism producing power law etc. distributions
Li, Heling; Shen, Hongjun; Yang, Bin
2017-07-01
Power law distribution is playing an increasingly important role in the complex system study. Based on the insolvability of complex systems, the idea of incomplete statistics is utilized and expanded, three different exponential factors are introduced in equations about the normalization condition, statistical average and Shannon entropy, with probability distribution function deduced about exponential function, power function and the product form between power function and exponential function derived from Shannon entropy and maximal entropy principle. So it is shown that maximum entropy principle can totally replace equal probability hypothesis. Owing to the fact that power and probability distribution in the product form between power function and exponential function, which cannot be derived via equal probability hypothesis, can be derived by the aid of maximal entropy principle, it also can be concluded that maximal entropy principle is a basic principle which embodies concepts more extensively and reveals basic principles on motion laws of objects more fundamentally. At the same time, this principle also reveals the intrinsic link between Nature and different objects in human society and principles complied by all.
Directly Specifying the Power Semicircle Distribution
Homei, Hazhir
2013-01-01
A new proof for a newly proved conjecture of Soltani and Roozegar (2012) is provided; our proof does not make any use of the Stieltjes transform unlike the proof of Roozegar and Soltani (2013), and the distribution of power semicircle has been directly specified, contrary to the authors' claim in (Roozegar and Soltani 2013).
Optimal Distributed Voltage Regulation in Power Distribution Networks
Lam, Albert Y S; Dominguez-Garcia, Alejandro; Tse, David
2012-01-01
In this paper, we address the problem of voltage regulation in power distribution networks with deep-penetration of distributed energy resources (DERs), e.g., renewable-based generation, and storage-capable loads such as plug-in hybrid electric vehicles. We cast the problem as an optimization program, where the objective is to minimize the losses in the network subject to constraints on bus voltage magnitudes, limits on active and reactive power injections, transmission line thermal limits and losses. We provide sufficient conditions under which the optimization problem can be solved via its convex relaxation. Using data from existing networks, we show that the conditions are expected to be satisfied by most networks. We also provide an efficient distributed algorithm to solve the problem. The algorithm is asynchronous, with a communication topology that is the same as the electrical network topology. We illustrate the algorithm's performance in the IEEE 34-bus and the 123-bus feeder test systems.
Improvement of power quality using distributed generation
Energy Technology Data Exchange (ETDEWEB)
Moreno-Munoz, A.; Lopez-Rodriguez, M.A.; Flores-Arias, J.M.; Bellido-Outerino, F.J. [Universidad de Cordoba, Departamento A.C., Electronica y T.E., Escuela Politecnica Superior, Campus de Rabanales, E-14071 Cordoba (Spain); de-la-Rosa, J.J.G. [Universidad de Cadiz, Area de Electronica, Dpto. ISA, TE y Electronica, Escuela Politecnica Superior Avda, Ramon Puyol, S/N, E-11202-Algeciras-Cadiz (Spain); Ruiz-de-Adana, M. [Universidad de Cordoba, Departamento de Quimica Fisica y Termodinamica Aplicada, Campus de Rabanales, E-14071 Cordoba (Spain)
2010-12-15
This paper addresses how Distributed Generation (DG), particularly when configured in Combined Heat and Power (CHP) mode, can become a powerful reliability solution in highlight automated factories, especially when integrated with complimentary Power Quality (PQ) measures. The paper presents results from the PQ audit conducted at a highly automated plant over last year. It was found that the main problems for the equipment installed were voltage sags. Among all categories of electrical disturbances, the voltage sag (dip) and momentary interruption are the nemeses of the automated industrial process. The paper analyzes the capabilities of modern electronic power supplies and the convenience of embedded solution. Finally it is addressed the role of the DG/CHP on the reliability of digital factories. (author)
DC-DC switching converter based power distribution vs serial power distribution EMC strategies
Arteche, F; Iglesias, M; Rivetta, C; Arcega, F G; Vila, I
2009-01-01
This paper presents a detailed and comparative analysis from the electromagnetic compatibility point of view of the proposed power distributions for the SLHC tracker up-grade. The main idea is to identify and quantify the noise sources, noise distribution at the system level and the sensitive areas in the front-end electronics corresponding to both proposed topologies: The DC-DC converter based power distribution and the serial power distribution. These studies will be used to define critical points on both systems to be studied and prototyped to ensure the correct integration of the system taking critically into account the electromagnetic compatibility. This analysis at the system level is crucial to ensure the final performance of the detector using non conventional power distributions, avoiding interference problems and excessive losses that can lead to catastrophic failures or expensive and un-practical solutions.
DISTRIBUTION OF ABO BLOOD GROUPS IN IRAN
Directory of Open Access Journals (Sweden)
K.Montazemi
1978-03-01
Full Text Available During the period 2530-36, population and health studies have been carried out by the School of Public Health and Institute of Public Health Research in different parts of Iran (Roodsar, Gonbad-Kavoos, Western Azarbaijan, Isfahan, Ghasghai tribe and Saheli Province. Genetic aspects including the distribution of ABO blood groups and Rh in various populations was specially considered in these surveys. Sampling was fulfilled on the basis of "stratified cluster sampling" in all the above mentioned areas. A total of 17,659 blood groups O,A,B and AB at the rate of 39.7, 25.4 and 6.2 per cent and also Rhesus positives and negatives at 93.1 and 6.9 per cent respectively. Regarding the distribution of ABO blood group in some populations we have found our results similar to those of Asiatic Indians and European gypsies. Also, comparison of the results showed the lowest incidence of Rhesus-negatives in Turkamans (1.5 per cent.
Security Constrained Distributed Optimal Power Flow of Interconnected Power Systems
Institute of Scientific and Technical Information of China (English)
BINKOU Alhabib; YU Yixin
2008-01-01
The security constrained distributed optimal power flow (DOPF) of interconnected power systems is presented. The centralized OPF problem of the multi-area power systems is decomposed into independent DOPF subproblems, one for each area. The dynamic security region (DSR) to guarantee the transient stability constraints and static voltage stability region (SVSR) constraints, and line current limits are included as constraints. The solutions to the DOPF subproblems of the different areas are coordinated through a pricing mechanism until they converge to the centralized OPF solution. The nonlinear DOPF subproblem is solved by predictor-corrector interior point method (PCIPM). The IEEE three-area RTS-96 system is worked out in order to demonstrate the effectiveness of the proposed method.
Distributed Power-Generation Systems and Protection
DEFF Research Database (Denmark)
Blaabjerg, Frede; Yang, Yongheng; Yang, Dongsheng
2017-01-01
penetration degree of renewable energy, among which wind and solar photovoltaics are typical sources. The integration level of the DPGS into the grid plays a critical role in developing sustainable and resilient power systems, especially with highly intermittent renewable energy resources. To address...... for the DPGS to consolidate the integration. In light of the above, this paper reviews the power-conversion and control technologies used for DPGSs. The impacts of the DPGS on the distributed grid are also examined, and more importantly, strategies for enhancing the connection and protection of the DPGS...
Distributed Wireless Power Transfer With Energy Feedback
Lee, Seunghyun; Zhang, Rui
2017-04-01
Energy beamforming (EB) is a key technique for achieving efficient radio-frequency (RF) transmission enabled wireless energy transfer (WET). By optimally designing the waveforms from multiple energy transmitters (ETs) over the wireless channels, they can be constructively combined at the energy receiver (ER) to achieve an EB gain that scales with the number of ETs. However, the optimal design of EB waveforms requires accurate channel state information (CSI) at the ETs, which is challenging to obtain practically, especially in a distributed system with ETs at separate locations. In this paper, we study practical and efficient channel training methods to achieve optimal EB in a distributed WET system. We propose two protocols with and without centralized coordination, respectively, where distributed ETs either sequentially or in parallel adapt their transmit phases based on a low-complexity energy feedback from the ER. The energy feedback only depends on the received power level at the ER, where each feedback indicates one particular transmit phase that results in the maximum harvested power over a set of previously used phases. Simulation results show that the two proposed training protocols converge very fast in practical WET systems even with a large number of distributed ETs, while the protocol with sequential ET phase adaptation is also analytically shown to converge to the optimal EB design with perfect CSI by increasing the training time. Numerical results are also provided to evaluate the performance of the proposed distributed EB and training designs as compared to other benchmark schemes.
Optimal power flow for distribution networks with distributed generation
Directory of Open Access Journals (Sweden)
Radosavljević Jordan
2015-01-01
Full Text Available This paper presents a genetic algorithm (GA based approach for the solution of the optimal power flow (OPF in distribution networks with distributed generation (DG units, including fuel cells, micro turbines, diesel generators, photovoltaic systems and wind turbines. The OPF is formulated as a nonlinear multi-objective optimization problem with equality and inequality constraints. Due to the stochastic nature of energy produced from renewable sources, i.e. wind turbines and photovoltaic systems, as well as load uncertainties, a probabilisticalgorithm is introduced in the OPF analysis. The Weibull and normal distributions are employed to model the input random variables, namely the wind speed, solar irradiance and load power. The 2m+1 point estimate method and the Gram Charlier expansion theory are used to obtain the statistical moments and the probability density functions (PDFs of the OPF results. The proposed approach is examined and tested on a modified IEEE 34 node test feeder with integrated five different DG units. The obtained results prove the efficiency of the proposed approach to solve both deterministic and probabilistic OPF problems for different forms of the multi-objective function. As such, it can serve as a useful decision-making supporting tool for distribution network operators. [Projekat Ministarstva nauke Republike Srbije, br. TR33046
Prediction of heater power distribution in radiative cylindrical furnaces
Energy Technology Data Exchange (ETDEWEB)
Ravichandran, M.; Dilber, I.; Torok, D.
1999-07-01
In the design of long radiative cylindrical furnaces, it is important to control the temperature variation along the furnace walls and consequently the temperature distribution in the processed material by selectively adjusting the power input to heater rods located circumferentially around the furnace walls. The heaters are grouped in zones located at different axial locations. By adjusting the power to each zone a specified temperature distribution along the furnace can be attained. The radiative interchange between different axial zones of the furnace affects the temperature distribution; this interchange is also impacted by the shadowing caused by the presence of the load, i.e. the processed material. A desired temperature distribution can only be achieved by selectively changing the power input to the heaters. For an a priori assessment of the commercial viability of using process friendly temperature distributions, it is necessary to determine: (a) the maximum power demand from each zone; (b) if active cooling is inevitable and (c) the bounds on temperature distribution that can be achieved without active cooling. It is therefore extremely useful to be able to predict the input power distribution for achieving desired furnace temperature profiles. For a given power input, the temperature distribution inside the furnace could be obtained by using a general purpose Computational Fluid Dynamics (CFD) software, such as FIDAP. A new methodology is developed within the framework of FIDAP software to eliminate the manual trial and error method. The method is based on obtaining the sensitivity of the temperature at the desired locations of the furnace as a function of the power input to the heating elements. Using these sensitivity coefficients, an iterative scheme is designed to adjust the boundary conditions (power to the heating elements in this case) based on the discrepancy of the solution temperatures from the desired temperature distribution. For each of these
Electrical power systems for distributed generation
Energy Technology Data Exchange (ETDEWEB)
Robertson, T.A.; Huval, S.J. [Stewart & Stevenson Services, Inc., Houston, TX (United States)
1996-12-31
{open_quotes}Distributed Generation{close_quotes} has become the {open_quotes}buzz{close_quotes} word of an electric utility industry facing deregulation. Many industrial facilities utilize equipment in distributed installations to serve the needs of a thermal host through the capture of exhaust energy in a heat recovery steam generator. The electrical power generated is then sold as a {open_quotes}side benefit{close_quotes} to the cost-effective supply of high quality thermal energy. Distributed generation is desirable for many different reasons, each with unique characteristics of the product. Many years of experience in the distributed generation market has helped Stewart & Stevenson to define a range of product features that are crucial to most any application. The following paper will highlight a few of these applications. The paper will also examine the range of products currently available and in development. Finally, we will survey the additional services offered by Stewart & Stevenson to meet the needs of a rapidly changing power generation industry.
Understanding crowd-powered search groups: a social network perspective.
Directory of Open Access Journals (Sweden)
Qingpeng Zhang
Full Text Available BACKGROUND: Crowd-powered search is a new form of search and problem solving scheme that involves collaboration among a potentially large number of voluntary Web users. Human flesh search (HFS, a particular form of crowd-powered search originated in China, has seen tremendous growth since its inception in 2001. HFS presents a valuable test-bed for scientists to validate existing and new theories in social computing, sociology, behavioral sciences, and so forth. METHODOLOGY: In this research, we construct an aggregated HFS group, consisting of the participants and their relationships in a comprehensive set of identified HFS episodes. We study the topological properties and the evolution of the aggregated network and different sub-groups in the network. We also identify the key HFS participants according to a variety of measures. CONCLUSIONS: We found that, as compared with other online social networks, HFS participant network shares the power-law degree distribution and small-world property, but with a looser and more distributed organizational structure, leading to the diversity, decentralization, and independence of HFS participants. In addition, the HFS group has been becoming increasingly decentralized. The comparisons of different HFS sub-groups reveal that HFS participants collaborated more often when they conducted the searches in local platforms or the searches requiring a certain level of professional knowledge background. On the contrary, HFS participants did not collaborate much when they performed the search task in national platforms or the searches with general topics that did not require specific information and learning. We also observed that the key HFS information contributors, carriers, and transmitters came from different groups of HFS participants.
Embeddings of (proper) power graphs of finite groups
Doostabadi, Alireza; Ghouchan, Mohammad Farrokhi Derakhshandeh
2014-01-01
The (proper) power graph of a group is a graph whose vertex set is the set of all (nontrivial) elements of the group and two distinct vertices are adjacent if one is a power of the other. Various kinds of planarity of (proper) power graphs of groups are discussed.
2010-03-05
...-72,718B] Briggs & Stratton Power Products Group, LLC., Home Power Division, a Subsidiary of Briggs... Group, and Aerotek, Jefferson, WI; Briggs & Stratton Power Products Group, LLC., Home Power Division... Lifestyle Staffing, Adecco, Techstaff, The Alaris Group, and Aerotek, Jefferson, WI; Briggs & Stratton...
Geothermal Power Potential in the Tatun Volcano Group, Taiwan
Tseng, H. H.; Song, S.
2013-12-01
Recent energy issues have concentrated the attention on finding alternative ones. National demands for renewable and sustainable energy increase rapidly, especially the geothermal power production, which is viewed as the most potential opportunity. This study attempts to estimate the geothermal powers in the Tatung Volcano Group (TVG), Taiwan and evaluate the possibility to develop the Enhanced Geothermal System. Tatung Volcano Group is located at the northwest part of Taiwan. It has violent volcanism during 0.8-0.20Ma, and is still active with many thermal manifestations. The young volcanic activity provides the TVG with high geothermal gradient and is well suitable for exploiting geothermal resources. Many explorations on geothermal energy have been accomplished in this area during1966-1973. They included resistivity survey, magnetic prospecting, gravity method, seismic prospecting and etc. In this study, we base on previous data and apply the probabilistic volumetric method proposed by Geotherm EX Inc., modified from the approach introduced by the USGS to evaluate the geothermal power potential in TVG. Meanwhile, use a Monte Carlo simulation technique to calculate the probability distribution of potentially recoverable energy reserves. The results show that the mean value is 270Mw, and P50 is 254Mw for 30 years, separately. Furthermore, the power potential of enhanced geothermal system in TVG is also estimated by the quantitative model proposed by Massachusetts Institute of Technology (MIT 2006). The results suggest that the mean value is 3,000 MW and P50 is 2,780 MW for 30 years, separately.
Groups of Prime Power Order v. 3
Berkovich, Yakov
2011-01-01
This is the third volume of a comprehensive and elementary treatment of finite p-group theory. Topics covered in this volume: (a) impact of minimal nonabelian subgroups on the structure of p-groups, (b) classification of groups all of whose nonnormal subgroups have the same order, (c) degrees of irreducible characters of p-groups associated with finite algebras, (d) groups covered by few proper subgroups, (e) p-groups of element breadth 2 and subgroup breadth 1, (f) exact number of subgroups of given order in a metacyclic p-group, (g) soft subgroups, (h) p-groups with a maximal elementary abel
Guinote, Ana; Judd, Charles M; Brauer, Markus
2002-05-01
The perception of group variability is affected by social power and status. Three different mechanisms may be responsible for these effects: (a) the power of the perceiver affects perceived group variability; (b) the power of the perceived group affects its perceived variability; and (c) the power of the group affects its actual variability. Two studies are reported to tease apart these three mechanisms and provide support for the third. In the first study, high- and low-power groups interacted and subsequently judged each other. In the second study, participants observed and rated the Study 1 groups, either knowing their power relationship or not. Results suggest that members of high-power groups manifest greater interpersonal variability than members of low-power groups.
Noise analysis in power distribution systems
Danisor, Alin
2016-12-01
This paper proposes an analysis, especially in time domain, of the electrical noise existent on the power distribution lines. This study is important for the use of powerlines as a channel of information transmissions. This information may refer to analog signals and as well to digital signals. The main problem addressed in this paper consists in the characterization of the background noise and to establish his statistical proprieties. It is very important to know if the noise induced in the transmission channel is a stationary one, or even an ergodic one. The main parameters like the mean value, the mean square value were determined in this paper. The approximation of the probability density function of each statistical parameter was studied. The pulses induced in the transmission channel by the transient phenomena of the power electrical systems were considered deterministic signals and their contributions were not included in this study.
Power system operations: State estimation distributed processing
Ebrahimian, Mohammad Reza
We present an application of a robust and fast parallel algorithm to power system state estimation with minimal amount of modifications to existing state estimators presently in place using the Auxiliary Problem Principle. We demonstrate its effectiveness on IEEE test systems, the Electric Reliability Counsel of Texas (ERCOT), and the Southwest Power Pool (SPP) systems. Since state estimation formulation may lead to an ill-conditioned system, we provide analytical explanations of the effects of mixtures of measurements on the condition of the state estimation information matrix. We demonstrate the closeness of the analytical equations to condition of several test case systems including IEEE RTS-96 and IEEE 118 bus systems. The research on the condition of the state estimation problem covers the centralized as well as distributed state estimation.
Distributed power generation using biogas fuelled microturbines
Energy Technology Data Exchange (ETDEWEB)
Pointon, K.; Langan, M.
2002-07-01
This research sought to analyse the market for small scale biogas fuelled distributed power generation, to demonstrate the concept of a biogas fuelled microturbine using the Capstone microturbine in conjunction with an anaerobic digester, and undertake a technico-economic evaluation of the biogas fuelled microturbine concept. Details are given of the experimental trials using continuous and batch digesters, and feedstocks ranging from cow and pig slurries to vegetable wastes and municipal solid waste. The yields of methane are discussed along with the successful operation of the microturbine with biogas fuels, and anaerobic digestion projects.
Structure Learning in Power Distribution Networks
Energy Technology Data Exchange (ETDEWEB)
Deka, Deepjyoti [Univ. of Texas, Austin, TX (United States); Chertkov, Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Backhaus, Scott N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-01-13
Traditionally power distribution networks are either not observable or only partially observable. This complicates development and implementation of new smart grid technologies, such as these related to demand response, outage detection and management, and improved load-monitoring. Here, inspired by proliferation of the metering technology, we discuss statistical estimation problems in structurally loopy but operationally radial distribution grids consisting in learning operational layout of the network from measurements, e.g. voltage data, which are either already available or can be made available with a relatively minor investment. Our newly suggested algorithms apply to a wide range of realistic scenarios. The algorithms are also computationally efficient – polynomial in time – which is proven theoretically and illustrated computationally on a number of test cases. The technique developed can be applied to detect line failures in real time as well as to understand the scope of possible adversarial attacks on the grid.
Power Law Distributions in Two Community Currencies
Kichiji, N.; Nishibe, M.
2007-07-01
The purpose of this paper is to highlight certain newly discovered social phenomena that accord with Zipf's law, in addition to the famous natural and social phenomena including word frequencies, earthquake magnitude, city size, income1 etc. that are already known to follow it. These phenomena have recently been discovered within the transaction amount (payments or receipts) distributions within two different Community Currencies (CC) that had been initiated as social experiments. One is a local CC circulating in a specific geographical area, such as a town. The other is a virtual CC used among members who belong to a certain community of interest (COI) on the Internet. We conducted two empirical studies to estimate the economic vitalization effects they had on their respective local economies. The results we found were that the amount of transactions (payments and receipts) of the two CCs was distributed according to a power-law distribution with a unity rank exponent. In addition, we found differences between the two CCs with regard to the shapes of their distribution over a low-transaction range. The result may originate from the difference in methods of issuing CCs or in the magnitudes of the minimum-value unit; however, this result calls for further investigation.
Distributed Algorithms for Optimal Power Flow Problem
Lam, Albert Y S; Tse, David
2011-01-01
Optimal power flow (OPF) is an important problem for power generation and it is in general non-convex. With the employment of renewable energy, it will be desirable if OPF can be solved very efficiently so its solution can be used in real time. With some special network structure, e.g. trees, the problem has been shown to have a zero duality gap and the convex dual problem yields the optimal solution. In this paper, we propose a primal and a dual algorithm to coordinate the smaller subproblems decomposed from the convexified OPF. We can arrange the subproblems to be solved sequentially and cumulatively in a central node or solved in parallel in distributed nodes. We test the algorithms on IEEE radial distribution test feeders, some random tree-structured networks, and the IEEE transmission system benchmarks. Simulation results show that the computation time can be improved dramatically with our algorithms over the centralized approach of solving the problem without decomposition, especially in tree-structured...
Robust distribution and use of electric power
Catalan Izquierdo, Saturnino
2001-07-01
One of the major problems related to the simultaneous operation of electrical converters in a wide open power system is the concordance between the characteristics of the feeder itself and the load. Nowadays we usually call Electric Power Quality or Electromagnetic Compatibility to this Concordance Degree. Currently, the most important non concordance are voltage sag (voltage dip) and short time interruptions, that is: decreasings in voltage RMS value lasting from some tenths of a second to several seconds. Current analysis usually study this problem from the feeder side, by means of morphological or stadistical approaches, or from the load side in order to evaluate immunity, emission or specific solutions. This line of research, undoubtly needed provided we need to know the current state of the power system and to increase the concordance degree, is not enough because of the huge variability between power lines and from one instant to another. Moreover, the legal boundaries that can support business decisions are not developed yet. The proposed new theory is widely contrasted by field and laboratory measurement. Detailed analysis include instant voltage, instant current, power system and load effects from many places inside the power system of Spain. This theory is a novel approach to the determination of Concordance Degree (CG) of a whole system (be it a distribution line or a single machine) and to the corrective steps needed to increase it. In addition, the proposed model allow a quantitative evaluation of corrective actions like the increase of energy system storage (in a mechanical to electrical convertible form) or/and the increase of the supplied reactive power. Profitability of corrective actions is mainly a function of the number of voltage dips (sags) and short time interruptions that happen in a given period of time. To reduce this number we have studied and developed new fault characterization and location algorithms designed specifically for medium
Dynamic Placement of Wind Power Distributed Generation Units in Distribution Power Systems
DEFF Research Database (Denmark)
Hajizadeh, Amin; Baghayipour, Mohammad Reza
2017-01-01
process. Thereby, an accurate dynamic model of the active and reactive powers injected by Wind DG to the system is employed in which the interactions between the Wind DG and the distribution network are well regarded. Finally, simulation results are given to show the capability of proposed approach......The placement problem of Distributed Generators (DGs) in distribution networks becomes much more complicated in the case of using the DGs with renewable energy resources, due to several causes like their intermittent output powers, the interactions between DGs and the rest of distribution network......, and other involved uncertainties. This paper develops a new approach for optimal placement of Wind DGs in which all of such influences are perfectly handled. This method simultaneously considers the time variations of dynamic nodal demands, nodal voltage magnitudes, and wind speed in the Wind DG placement...
Electric power processing, distribution, management and energy storage
Giudici, R. J.
1980-01-01
Power distribution subsystems are required for three elements of the SPS program: (1) orbiting satellite, (2) ground rectenna, and (3) Electric Orbiting Transfer Vehicle (EOTV). Power distribution subsystems receive electrical power from the energy conversion subsystem and provide the power busses rotary power transfer devices, switchgear, power processing, energy storage, and power management required to deliver control, high voltage plasma interactions, electric thruster interactions, and spacecraft charging of the SPS and the EOTV are also included as part of the power distribution subsystem design.
Is Distributed Cognition Group Level Cognition?
Directory of Open Access Journals (Sweden)
Ludwig Kirk
2015-09-01
Full Text Available This paper shows that recent arguments from group problem solving and task performance to emergent group level cognition that rest on the social parity and related principles are invalid or question begging. The paper shows that standard attributions of problem solving or task performance to groups require only multiple agents of the outcome, not a group agent over and above its members, whether or not any individual member of the group could have accomplished the task independently.
Groups of Prime Power Order v 1
Berkovich, Yakov
2008-01-01
This is the first of three volumes on finite p-group theory. It presents the state of the art and in addition contains numerous new and easy proofs of famous theorems, many exercises (some of them with solutions), and about 1500 open problems. It is expected to be useful to certain applied mathematics areas, such as combinatorics, coding theory, and computer sciences. The book should also be easily comprehensible to students and scientists with some basic knowledge of group theory and algebra.
Distributed Robust Power System State Estimation
Kekatos, Vassilis
2012-01-01
Deregulation of energy markets, penetration of renewables, advanced metering capabilities, and the urge for situational awareness, all call for system-wide power system state estimation (PSSE). Implementing a centralized estimator though is practically infeasible due to the complexity scale of an interconnection, the communication bottleneck in real-time monitoring, regional disclosure policies, and reliability issues. In this context, distributed PSSE methods are treated here under a unified and systematic framework. A novel algorithm is developed based on the alternating direction method of multipliers. It leverages existing PSSE solvers, respects privacy policies, exhibits low communication load, and its convergence to the centralized estimates is guaranteed even in the absence of local observability. Beyond the conventional least-squares based PSSE, the decentralized framework accommodates a robust state estimator. By exploiting interesting links to the compressive sampling advances, the latter jointly es...
Believing the Power of the Group
Institute of Scientific and Technical Information of China (English)
Tom Xue; Flora Zhao
2011-01-01
The New York Co-Location Exhibitions (TEXWORLD USA/International Apparel Sourcing Expo/Home Textile Sourcing Expo) are to stage on the same spot as last year from July 19th - 21st,2011,strongly attracting the textile enterprises to itch to go for more business opportunity as well as the new market.Wenzhou,wellknown for its fashion industry,has grasped the chance to organize its member enterprises as a group pavilion to go to New York for much more success.The reporters of the magazine interviewed the Secretary of Wenzhou Fashion Association,Chen Qixiang,for some information of the group.
DISTRIBUTED ELECTRICAL POWER PRODUCTION SYSTEM AND METHOD OF CONTROL THEREOF
DEFF Research Database (Denmark)
2010-01-01
The present invention relates to a distributed electrical power production system wherein two or more electrical power units comprise respective sets of power supply attributes. Each set of power supply attributes is associated with a dynamic operating state of a particular electrical power unit....
14 CFR 25.1310 - Power source capacity and distribution.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Power source capacity and distribution. 25... supply. The power sources and the system must be able to supply the following power loads in probable... source of power is required, after any failure or malfunction in any one power supply system...
Wireless powering for low-power distributed sensors
Directory of Open Access Journals (Sweden)
Popović Zoya B.
2006-01-01
Full Text Available In this paper, an overview of the field of wireless powering is presented with an emphasis on low-power applications. Several rectenna elements and arrays are discussed in more detail: (1 a 10-GHz array for powering sensors in aircraft wings; (2 a single antenna in the 2.4-GHz ISM band for low-power assisted-living sensors; and (3 a broadband array for power harvesting in the 2-18GHz frequency range.
Chen, Yanguang
2013-01-01
The different between the inverse power function and the negative exponential function is significant. The former suggests a complex distribution, while the latter indicates a simple distribution. However, the association of the power-law distribution with the exponential distribution has been seldom researched. Using mathematical derivation and numerical experiments, I reveal that a power-law distribution can be created through averaging an exponential distribution. For the distributions defined in a 1-dimension space, the scaling exponent is 1; while for those defined in a 2-dimension space, the scaling exponent is 2. The findings of this study are as follows. First, the exponential distributions suggest a hidden scaling, but the scaling exponents suggest a Euclidean dimension. Second, special power-law distributions can be derived from exponential distributions, but they differ from the typical power-law distribution. Third, it is the real power-law distribution that can be related with fractal dimension. ...
Business Pattern of Distributed Energy in Electric Power System Reformation
Liang, YUE; Zhuochu, LIU; Jun, LI; Siwei, LI
2017-05-01
Under the trend of the electric power system revolution, the operation mode of micro power grid that including distributed power will be more diversified. User’s demand response and different strategies on electricity all have great influence on the operation of distributed power grid. This paper will not only research sensitive factors of micro power grid operation, but also analyze and calculate the cost and benefit of micro power grid operation upon different types. Then it will build a tech-economic calculation model, which applies to different types of micro power grid under the reformation of electric power system.
Projective Power Entropy and Maximum Tsallis Entropy Distributions
Shinto Eguchi; Shogo Kato; Osamu Komori
2011-01-01
We discuss a one-parameter family of generalized cross entropy between two distributions with the power index, called the projective power entropy. The cross entropy is essentially reduced to the Tsallis entropy if two distributions are taken to be equal. Statistical and probabilistic properties associated with the projective power entropy are extensively investigated including a characterization problem of which conditions uniquely determine the projective power entropy up to the power index...
A Note on Primitive Permutation Groups of Prime Power Degree
Qian Cai; Hua Zhang
2015-01-01
Primitive permutation groups of prime power degree are known to be affine type, almost simple type, and product action type. At the present stage finding an explicit classification of primitive groups of affine type seems untractable, while the product action type can usually be reduced to almost simple type. In this paper, we present a short survey of the development of primitive groups of prime power degree, together with a brief description on such groups.
Management issues power quality in distribution system
2011-01-01
In recent years, the number of power quality problems has increased dramatically. This increase in electricity demand of recent years, consecutively with increasing the number of power plants and power, along with changing the structure of energy agents and increasepower receivers, led to deterioration of power quality parameters, with implications serious about working arrangements and consumer networks. Most disputed aspect in terms of power quality standards is the regime's control sizes. ...
Intrinsic thermoelectric power of group VB metals
Directory of Open Access Journals (Sweden)
Gunadhor Singh Okram
2012-03-01
Full Text Available We have reinvestigated the thermopower of group VB metals in polycrystalline forms in the temperature range of 6-300K, taking into account the critical nature of the sample surface and heat treatment especially for niobium. Strikingly small magnitude, negative sign, phonon drag dip and superconductivity not reported previously were observed in surface-cleaned single crystalline Nb. However, while thermopower magnitudes are small, mixed signs were found in the polycrystalline V, Nb and Ta samples. These properties were therefore interpreted as their intrinsic properties and were briefly discussed taking into account of the existing theory by fitting also the data that give the Fermi energies of 10.94 eV, 5.08 eV and 1.86eV, respectively.
Locational Marginal Pricing in the Campus Power System at the Power Distribution Level
Energy Technology Data Exchange (ETDEWEB)
Hao, Jun; Gu, Yi; Zhang, Yingchen; Zhang, Jun Jason; Gao, David Wenzhong
2016-11-14
In the development of smart grid at distribution level, the realization of real-time nodal pricing is one of the key challenges. The research work in this paper implements and studies the methodology of locational marginal pricing at distribution level based on a real-world distribution power system. The pricing mechanism utilizes optimal power flow to calculate the corresponding distributional nodal prices. Both Direct Current Optimal Power Flow and Alternate Current Optimal Power Flow are utilized to calculate and analyze the nodal prices. The University of Denver campus power grid is used as the power distribution system test bed to demonstrate the pricing methodology.
Energy Technology Data Exchange (ETDEWEB)
Katiraei, F.; Yazdani, A.; Uluski, R. [Quanta Technology, New York, NY (United States); Vaziri, M. [Pacific Gas and Electric Co., San Fransisco, CA (United States)
2009-07-01
Problems regarding voltage regulation on distribution feeders arise when there is a large demand for reactive power. The addition of distributed generation changes the power flow and voltage profile of a power system. The current practice is to use distributed generation passively and perform voltage regulation as before. However, this may not function well with high distributed generation penetration. This presentation discussed voltage regulation and the reactive power supply capability of distributed generation. Several applications in active distribution systems were presented. Specifically, the presentation discussed distributed interconnection challenges; utility practices and limiting factors; and the real and reactive power capabilities of distributed generation. A case study was also presented. It was concluded that in order for distributed generation to actively participate in real and reactive power management of distribution systems, a change is needed in standards and utility guidelines, along with a better understanding of distributed generation technologies and controls. 1 tab., 11 figs.
Power in group contexts: the influence of group status on promotion and prevention decision making.
Scheepers, Daan; Ellemers, Naomi; Sassenberg, Kai
2013-06-01
This research examines how group status affects the impact of individual power positions on promotion versus prevention choices in group decision making. We consider that high power not only implies control, but also indicates responsibility for the achievement of group goals. We argue that the nature of these goals depends on the current status of the group. In Experiment 1, individuals who were accorded high power showed more promotion-oriented decisions in the low group status condition while decisions were more prevention oriented under high group status. Experiment 2 replicated these effects, and further demonstrated that they only emerge when those in power are explicitly made accountable for the achievement of group goals. These results are discussed in relation to regulatory focus theory, power theories, and the role of social identities and group goals in group dynamics.
Why some groups just feel better: the regulatory fit of group power.
Sassenberg, Kai; Jonas, Kai J; Shah, James Y; Brazy, Paige C
2007-02-01
The current research applied the regulatory fit hypothesis (E. T. Higgins, 2000) to the evaluation of groups, suggesting that individuals' group appraisal depends on how well the groups fit their regulatory needs. Specifically, it was predicted that higher power groups would fit and be more valued by those individuals with a promotion focus because these groups provide a better opportunity to sustain nurturance and achievement needs. Alternatively, lower power groups were predicted to fit and be more valued by those individuals with a prevention focus because these groups necessitate (and thus sustain) a focus on safety and security. Five studies found support for these predictions by both assessing and manipulating regulatory focus and group power and by using explicit and implicit measures of group attraction. Moreover, these regulatory fit effects occurred specifically for group power and not for general differences in group status.
Specifying Processes: Application to Electrical Power Distribution
Directory of Open Access Journals (Sweden)
Sabah Al-Fedaghi
2011-01-01
Full Text Available Problem statement: This study deals with the problem of how to specify processes. Many process specification methodologies have been determined to be incomplete; for example, ISO 9000:2005 defines process as transforming media inputs into outputs. Nevertheless, the author of the Quality Systems Handbook, declares that such a definition is incomplete because processes create results and not necessarily by transforming inputs. Still, it is not clear what description of process can embed transformation of input to output or include creation that leads to results. Approach: This problem is important because process specification is an essential component in building projects utilized in such tasks as scheduling, planning, production, management, work flow and reengineering. Results: We solve the problem by opening the black box in the input-transformation-output model. This action uncovers many possible sources and destinations related to input and output, such as the disappearance, storage and copying of input. It is possible to reject input and also to block output from leaving the process. The approach is based on a conceptual framework for process specification of all generic phases that make up any process and embraces input, transformation, creation and output. The study applies the method in the field of electrical power distribution systems. Conclusion: We conclude that the results demonstrate a viable specification method that can be adopted for different types of processes.
When does power disparity help or hurt group performance?
Tarakci, Murat; Greer, Lindred L; Groenen, Patrick J F
2016-03-01
Power differences are ubiquitous in social settings. However, the question of whether groups with higher or lower power disparity achieve better performance has thus far received conflicting answers. To address this issue, we identify 3 underlying assumptions in the literature that may have led to these divergent findings, including a myopic focus on static hierarchies, an assumption that those at the top of hierarchies are competent at group tasks, and an assumption that equality is not possible. We employ a multimethod set of studies to examine these assumptions and to understand when power disparity will help or harm group performance. First, our agent-based simulation analyses show that by unpacking these common implicit assumptions in power research, we can explain earlier disparate findings--power disparity benefits group performance when it is dynamically aligned with the power holder's task competence, and harms group performance when held constant and/or is not aligned with task competence. Second, our empirical findings in both a field study of fraud investigation groups and a multiround laboratory study corroborate the simulation results. We thereby contribute to research on power by highlighting a dynamic understanding of power in groups and explaining how current implicit assumptions may lead to opposing findings.
Distribution of power output when establishing a breakaway in cycling.
Abbiss, Chris R; Menaspà, Paolo; Villerius, Vincent; Martin, David T
2013-07-01
A number of laboratory-based performance tests have been designed to mimic the dynamic and stochastic nature of road cycling. However, the distribution of power output and thus physical demands of high-intensity surges performed to establish a breakaway during actual competitive road cycling are unclear. Review of data from professional road-cycling events has indicated that numerous short-duration (5-15 s), high-intensity (~9.5-14 W/kg) surges are typically observed in the 5-10 min before athletes' establishing a breakaway (ie, riding away from a group of cyclists). After this initial high-intensity effort, power output declined but remained high (~450-500 W) for a further 30 s to 5 min, depending on race dynamics (ie, the response of the chase group). Due to the significant influence competitors have on pacing strategies, it is difficult for laboratory-based performance tests to precisely replicate this aspect of mass-start competitive road cycling. Further research examining the distribution of power output during competitive road racing is needed to refine laboratory-based simulated stochastic performance trials and better understand the factors important to the success of a breakaway.
Fuel Cycle Comparison for Distributed Power Technologies
Energy Technology Data Exchange (ETDEWEB)
Elgowainy, A. [Argonne National Lab. (ANL), Argonne, IL (United States); Wang, M. Q. [Argonne National Lab. (ANL), Argonne, IL (United States)
2008-11-15
This report examines backup power and prime power systems and addresses the potential energy and environmental effects of substituting fuel cells for existing combustion technologies based on microturbines and internal combustion engines.
Wind Farms’ Spatial Distribution Effect on Power System Reserves Requirements
DEFF Research Database (Denmark)
Sørensen, Poul Ejnar; Cutululis, Nicolaos Antonio
2010-01-01
in smaller areas, which causes the total wind power fluctuations in power system areas to increase significantly. The impact of future large wind farms spatial distribution with respect to the power system reserve requirements is analyzed in this paper. For this purpose, Correlated Wind (CorWind) power time...
Market power and contract form: evidence from physician group practices.
Town, Robert; Feldman, Roger; Kralewski, John
2011-06-01
We examine how the market power of physician groups affects the form of their contracts with health insurers. We develop a simple model of physician contracting based on 'behavioral economics' and test it with data from two sources: a survey of physician group practices in Minnesota; and the physician component of the Community Tracking Survey. In both data sets we find that increases in groups' market power are associated with proportionately more fee-for-service revenue and less revenue from capitation.
The Design of Power Distribution System for CYCIAE-100
Institute of Scientific and Technical Information of China (English)
GE; Tao; CAI; Hong-ru; LI; Zhen-guo
2012-01-01
<正>As an important component of CYCIAE-100, the power distribution system can be divided into four parts, i. e., RF system with a total power of 420 kW, water cooling system of 150 kW, vacuum system of 100 kW, and other devices with a total power of 450 kW. The design of power distribution system for CYCIAE-100 is based on three principles as listed below.
Price Based Local Power Distribution Management System (Local Power Distribution Manager) v1.0
Energy Technology Data Exchange (ETDEWEB)
2016-11-28
A trans-active energy micro-grid controller is implemented in the VOLTTRON distributed control platform. The system uses the price of electricity as the mechanism for conducting transactions that are used to manage energy use and to balance supply and demand. In order to allow testing and analysis of the control system, the implementation is designed to run completely as a software simulation, while allowing the inclusion of selected hardware that physically manages power. Equipment to be integrated with the micro-grid controller must have an IP (Internet Protocol)-based network connection and a software "driver" must exist to translate data communications between the device and the controller.
CHINALCO Repurchased Equity of Ningxia Electric Power Group
Institute of Scientific and Technical Information of China (English)
2013-01-01
<正>On the transformation road to promoting coal-power-aluminum integration, CHINALCO moved another step forward. Following the acquisition of 35.3% equity of Ningxia Electric Power Group in August, CHINALCO again announced to buy 23.66% equity of Ningxia
Distributed optimal coordination for distributed energy resources in power systems
DEFF Research Database (Denmark)
Wu, Di; Yang, Tao; Stoorvogel, A.
2017-01-01
Driven by smart grid technologies, distributed energy resources (DERs) have been rapidly developing in recent years for improving reliability and efficiency of distribution systems. Emerging DERs require effective and efficient coordination in order to reap their potential benefits. In this paper...
Why some groups just feel better : The regulatory fit of group power
Sassenberg, K.; Jonas, K.J; Shah, J.Y; Brazy, P.C
2007-01-01
The current research applied the regulatory fit hypothesis (E. T. Higgins, 2000) to the evaluation of groups, suggesting that individuals' group appraisal depends on how well the groups fit their regulatory needs. Specifically, it was predicted that higher power groups would fit and be more valued b
Distributed Power-Flow Controller (DPFC Simulation
Directory of Open Access Journals (Sweden)
T Jagan Mohan Rao
2014-10-01
Full Text Available This paper describes the steady-state response and control of power in transmission line equipped with FACTS devices. Detailed simulations are carried out on two -machine systems to illustrate the control features of these devices and their influence to increase power transfer capability and improve system reliability. The DPFC is derived from the unified power-flow controller (UPFC and DPFC has the same control capability as the UPFC. The DPFC can be considered as a UPFC with an eliminated common dc link. The active power exchange between the shunt and series converters, which is through the common dc link in the UPFC, is now through the transmission lines at the third -harmonic frequency. The interaction between the DPFC, the network and the machines are analyzed.
Decision-Making for Crisis Management of Power Distribution Networks
Directory of Open Access Journals (Sweden)
Amir Hossein JAHANIKIA
2015-01-01
Full Text Available This paper suggests a model to solve crises in power distribution network by using spreadsheets in order to make an optimum decision in this regard. Importance of crisis management in power distribution network is investigated from various aspects. Reductions in off times and immediate returns of power, as well as undistributed energy along subscribers` satisfaction are parameters considered in crisis management power distribution network. This paper solves a case about this issue by spreadsheets in order to provide a new model for decision makers to facilitate solving these kinds of problems.
Facts controllers in power transmission and distribution
Padiyar, KR
2007-01-01
About the Book: The emerging technology of Flexible AC Transmission System (FACTS) enables planning and operation of power systems at minimum costs, without compromising security. This is based on modern high power electronic systems that provide fast controllability to ensure ''flexible'' operation under changing system conditions. This book presents a comprehensive treatment of the subject by discussing the operating principles, mathematical models, control design and issues that affect the applications. The concepts are explained often with illustrative examples and case studies. In partic
Local Control of Reactive Power by Distributed Photovoltaic Generators
Turitsyn, Konstantin S; Backhaus, Scott; Chertkov, Misha
2010-01-01
High penetration levels of distributed photovoltaic (PV) generation on an electrical distribution circuit may severely degrade power quality due to voltage sags and swells caused by rapidly varying PV generation during cloud transients coupled with the slow response of existing utility compensation and regulation equipment. Although not permitted under current standards for interconnection of distributed generation, fast-reacting, VAR-capable PV inverters may provide the necessary reactive power injection or consumption to maintain voltage regulation under difficult transient conditions. As side benefit, the control of reactive power injection at each PV inverter provides an opportunity and a new tool for distribution utilities to optimize the performance of distribution circuits, e.g. by minimizing thermal losses. We suggest a local control scheme that dispatches reactive power from each PV inverter based on local instantaneous measurements of the real and reactive components of the consumed power and the re...
Grid Monitoring and Advanced Control of Distributed Power Generation Systems
Timbus, Adrian Vasile
2007-01-01
The movement towards a clean technology for energy production and the constraints in reducing the CO2 emissions are some factors facilitating the growth of distributed power generation systems based on renewable energy resources. Consequently, large penetration of distributed generators has been reported in some countries creating concerns about power system stability. This leads to a continuous evolution of grid interconnection requirements towards a better controllability of generated power...
The electric power engineering handbook electric power generation, transmission, and distribution
Grigsby, Leonard L
2012-01-01
Featuring contributions from worldwide leaders in the field, the carefully crafted Electric Power Generation, Transmission, and Distribution, Third Edition (part of the five-volume set, The Electric Power Engineering Handbook) provides convenient access to detailed information on a diverse array of power engineering topics. Updates to nearly every chapter keep this book at the forefront of developments in modern power systems, reflecting international standards, practices, and technologies. Topics covered include: * Electric Power Generation: Nonconventional Methods * Electric Power Generation
Options for Control of Reactive Power by Distributed Photovoltaic Generators
Sulc, Petr; Backhaus, Scott; Chertkov, Michael
2010-01-01
High penetration levels of distributed photovoltaic(PV) generation on an electrical distribution circuit present several challenges and opportunities for distribution utilities. Rapidly varying irradiance conditions may cause voltage sags and swells that cannot be compensated by slowly responding utility equipment resulting in a degradation of power quality. Although not permitted under current standards for interconnection of distributed generation, fast-reacting, VAR-capable PV inverters may provide the necessary reactive power injection or consumption to maintain voltage regulation under difficult transient conditions. As side benefit, the control of reactive power injection at each PV inverter provides an opportunity and a new tool for distribution utilities to optimize the performance of distribution circuits, e.g. by minimizing thermal losses. We discuss and compare via simulation various design options for control systems to manage the reactive power generated by these inverters. An important design de...
Coordination of baseload power plant group control with static reactive power compensator control
Directory of Open Access Journals (Sweden)
Zbigniew Szczerba
2012-06-01
Full Text Available Reactive power sources in power system nodes: generators and static reactive power compensators, are controlled by control systems. Generators – by generator node group controllers, compensators – by voltage controllers. The paper presents issues of these control systems’ coordination and proposals for its implementation.
Power-like Tail Observed in Weight Distributions of Schoolchildren
Kuninaka, Hiroto
2015-01-01
We investigated the statistical properties of the weight distributions of Japanese children who were born in 1996, from recent data. The weights of 16- and 17-year-old male children have a lognormal distribution with a power-like tail, which is best modeled by the double Pareto distribution. The emergence of the power-like tail may be attributed to the low probability that an obese person will attain a normal weight.
Endomorphism Algebras of Tensor Powers of Modules for Quantum Groups
DEFF Research Database (Denmark)
Andersen, Therese Søby
the group algebra of the braid group to the endomorphism algebra of any tensor power of the Weyl module with highest weight 2. We take a first step towards determining the kernel of this map by reformulating well-known results on the semisimplicity of the Birman-Murakami-Wenzl algebra in terms of the order...
The Power of Language in Computer-Mediated Groups.
Adkins, Mark; Brashers, Dale E.
1995-01-01
Discusses an experiment to find the effects of "powerful" and "powerless" language on small computer-mediated groups. Explains that subjects were asked to communicate via computer in a decision-making context. Describes the three conditions. Finds that language style has significant impact on impression formation in computer groups and that…
Communities of Inquiry: Politics, Power and Group Dynamics
Burgh, Gilbert; Yorshansky, Mor
2011-01-01
The notion of a community of inquiry has been treated by many of its proponents as being an exemplar of democracy in action. We argue that the assumptions underlying this view present some practical and theoretical difficulties, particularly in relation to distribution of power among the members of a community of inquiry. We identify two…
Parallel and distributed processing: applications to power systems
Energy Technology Data Exchange (ETDEWEB)
Wu, Felix; Murphy, Liam [California Univ., Berkeley, CA (United States). Dept. of Electrical Engineering and Computer Sciences
1994-12-31
Applications of parallel and distributed processing to power systems problems are still in the early stages. Rapid progress in computing and communications promises a revolutionary increase in the capacity of distributed processing systems. In this paper, the state-of-the art in distributed processing technology and applications is reviewed and future trends are discussed. (author) 14 refs.,1 tab.
Group handoff management in low power microcell-femtocell network
Directory of Open Access Journals (Sweden)
Debashis De
2017-02-01
Full Text Available This paper presents an analytical model of group based hand-off management based on bird flocking behavior. In the proposed scheme, a number of mobile devices form a group if these devices move together for a long time duration. Although call delivery or call generation are performed individually, hand-off is performed in a group. Dynamic group formation, group division and group merging methods are proposed in this paper. From the simulation results it is demonstrated that approximately 75%, 65% and 90% reduction in power, cost and latency consumption can be obtained respectively using group hand-off management. Thus the proposed scheme is referred as green, economic and fast hand-off strategy. In this paper instead of a macrocell network, a microcell-femtocell network is considered as the transmission power of a microcell or a femtocell base station is much less than a macrocell base station. Simulation results present that the microcell-femtocell network achieves approximately 25–55% and 35–55% reduction in power transmission, and 50–65% and 15–45% reduction in path loss than only a macrocell network and macrocell-femtocell network respectively. Thus microcell-femtocell network is a power-efficient network.
DEFF Research Database (Denmark)
Chen, Shuheng; Hu, Weihao; Chen, Zhe
2016-01-01
In this paper, an efficient methodology is proposed to deal with segmented-time reconfiguration problem of distribution networks coupled with segmented-time reactive power control of distributed generators. The target is to find the optimal dispatching schedule of all controllable switches...... and distributed generators’ reactive powers in order to minimize comprehensive cost. Corresponding constraints, including voltage profile, maximum allowable daily switching operation numbers (MADSON), reactive power limits, and so on, are considered. The strategy of grouping branches is used to simplify...... (FAHPSO) is implemented in VC++ 6.0 program language. A modified version of the typical 70-node distribution network and several real distribution networks are used to test the performance of the proposed method. Numerical results show that the proposed methodology is an efficient method for comprehensive...
Shenhuo Group,Yichuan Power and Yulian Group Jointly Establishing Henan Non-ferrous Holding Co.
Institute of Scientific and Technical Information of China (English)
2007-01-01
<正>Recently,Shenghuo Group,Yulian Group and Yichuan Power have made the decision to es- tablish Henan Non-ferrous Holding Group with a joint investment of 500 million yuan.It is originally scheduled to complete industrial and commercial registration by the end of June with registration in Zhendong New Area of Zhen- zhou.
Power-aware applications for scientific cluster and distributed computing
Abdurachmanov, David; Eulisse, Giulio; Grosso, Paola; Hillegas, Curtis; Holzman, Burt; Klous, Sander; Knight, Robert; Muzaffar, Shahzad
2014-01-01
The aggregate power use of computing hardware is an important cost factor in scientific cluster and distributed computing systems. The Worldwide LHC Computing Grid (WLCG) is a major example of such a distributed computing system, used primarily for high throughput computing (HTC) applications. It has a computing capacity and power consumption rivaling that of the largest supercomputers. The computing capacity required from this system is also expected to grow over the next decade. Optimizing the power utilization and cost of such systems is thus of great interest. A number of trends currently underway will provide new opportunities for power-aware optimizations. We discuss how power-aware software applications and scheduling might be used to reduce power consumption, both as autonomous entities and as part of a (globally) distributed system. As concrete examples of computing centers we provide information on the large HEP-focused Tier-1 at FNAL, and the Tigress High Performance Computing Center at Princeton U...
Communication Systems and Study Method for Active Distribution Power systems
DEFF Research Database (Denmark)
Wei, Mu; Chen, Zhe
Due to the involvement and evolvement of communication technologies in contemporary power systems, the applications of modern communication technologies in distribution power system are becoming increasingly important. In this paper, the International Organization for Standardization (ISO....... The suitability of the communication technology to the distribution power system with active renewable energy based generation units is discussed. Subsequently the typical possible communication systems are studied by simulation. In this paper, a novel method of integrating communication system impact into power...... system simulation is presented to address the problem of lack of off-shelf research tools on the power system communication. The communication system is configured and studied by the OPNET, and the performance of an active distribution power system integrated with the communication system is simulated...
Energy Technology Data Exchange (ETDEWEB)
Soendergren, C.; Norsk Jensen, A. (Dansk Energi, Frederiksberg (Denmark)); OEstergaard, J. (Danmarks Tekniske Univ.. DTU Elektro, Kgs. Lyngby (Denmark)) (and others)
2011-07-01
The Smart Grid Network was established in 2010 by the Danish climate and energy minister tasked with developing recommendations for future actions and initiatives that make it possible to handle up to 50% electricity from wind energy in the power system in 2020. The task of working group 1 of the Smart Grid Network is stated as: ''The group will, building on existing surveys and analyses of structures and constraints in the Danish electricity system 2020, define concrete ideas on the technical and system development needs for the electricity supply system when the goal of intelligent integration of 50 percent power generated by renewable energy must be met. The group should come up with concrete suggestions on how to make the power system future-oriented, such as new network and management architectures, more measuring equipment, optical sensors, and new computer and communications systems that can monitor, control and operate the power system with the aim that the new intelligence can contribute to a reliable and cost-effective power system that can handle the deployment of renewable energy''. The working group has focused on a general description of the whole overall system needs and more specifically on the power grid and its management and control. (LN)
Linear Power-Flow Models in Multiphase Distribution Networks: Preprint
Energy Technology Data Exchange (ETDEWEB)
Bernstein, Andrey; Dall' Anese, Emiliano
2017-05-26
This paper considers multiphase unbalanced distribution systems and develops approximate power-flow models where bus-voltages, line-currents, and powers at the point of common coupling are linearly related to the nodal net power injections. The linearization approach is grounded on a fixed-point interpretation of the AC power-flow equations, and it is applicable to distribution systems featuring (i) wye connections; (ii) ungrounded delta connections; (iii) a combination of wye-connected and delta-connected sources/loads; and, (iv) a combination of line-to-line and line-to-grounded-neutral devices at the secondary of distribution transformers. The proposed linear models can facilitate the development of computationally-affordable optimization and control applications -- from advanced distribution management systems settings to online and distributed optimization routines. Performance of the proposed models is evaluated on different test feeders.
Statistical analyses support power law distributions found in neuronal avalanches.
Directory of Open Access Journals (Sweden)
Andreas Klaus
Full Text Available The size distribution of neuronal avalanches in cortical networks has been reported to follow a power law distribution with exponent close to -1.5, which is a reflection of long-range spatial correlations in spontaneous neuronal activity. However, identifying power law scaling in empirical data can be difficult and sometimes controversial. In the present study, we tested the power law hypothesis for neuronal avalanches by using more stringent statistical analyses. In particular, we performed the following steps: (i analysis of finite-size scaling to identify scale-free dynamics in neuronal avalanches, (ii model parameter estimation to determine the specific exponent of the power law, and (iii comparison of the power law to alternative model distributions. Consistent with critical state dynamics, avalanche size distributions exhibited robust scaling behavior in which the maximum avalanche size was limited only by the spatial extent of sampling ("finite size" effect. This scale-free dynamics suggests the power law as a model for the distribution of avalanche sizes. Using both the Kolmogorov-Smirnov statistic and a maximum likelihood approach, we found the slope to be close to -1.5, which is in line with previous reports. Finally, the power law model for neuronal avalanches was compared to the exponential and to various heavy-tail distributions based on the Kolmogorov-Smirnov distance and by using a log-likelihood ratio test. Both the power law distribution without and with exponential cut-off provided significantly better fits to the cluster size distributions in neuronal avalanches than the exponential, the lognormal and the gamma distribution. In summary, our findings strongly support the power law scaling in neuronal avalanches, providing further evidence for critical state dynamics in superficial layers of cortex.
Statistical analyses support power law distributions found in neuronal avalanches.
Klaus, Andreas; Yu, Shan; Plenz, Dietmar
2011-01-01
The size distribution of neuronal avalanches in cortical networks has been reported to follow a power law distribution with exponent close to -1.5, which is a reflection of long-range spatial correlations in spontaneous neuronal activity. However, identifying power law scaling in empirical data can be difficult and sometimes controversial. In the present study, we tested the power law hypothesis for neuronal avalanches by using more stringent statistical analyses. In particular, we performed the following steps: (i) analysis of finite-size scaling to identify scale-free dynamics in neuronal avalanches, (ii) model parameter estimation to determine the specific exponent of the power law, and (iii) comparison of the power law to alternative model distributions. Consistent with critical state dynamics, avalanche size distributions exhibited robust scaling behavior in which the maximum avalanche size was limited only by the spatial extent of sampling ("finite size" effect). This scale-free dynamics suggests the power law as a model for the distribution of avalanche sizes. Using both the Kolmogorov-Smirnov statistic and a maximum likelihood approach, we found the slope to be close to -1.5, which is in line with previous reports. Finally, the power law model for neuronal avalanches was compared to the exponential and to various heavy-tail distributions based on the Kolmogorov-Smirnov distance and by using a log-likelihood ratio test. Both the power law distribution without and with exponential cut-off provided significantly better fits to the cluster size distributions in neuronal avalanches than the exponential, the lognormal and the gamma distribution. In summary, our findings strongly support the power law scaling in neuronal avalanches, providing further evidence for critical state dynamics in superficial layers of cortex.
Distribution of wind power resource over Pakistan
Energy Technology Data Exchange (ETDEWEB)
Nasir, S.M.; Raza, S.M.; Raja, I.A. (Balochistan Univ., Quetta (Pakistan). Dept. of Physics)
1992-01-01
The synthesis and presentation of the wind data are required to establish the wind resource climatology for an area. In this respect, wind contour maps are essential to visualize and quantify the variation of wind speed over the country. Using the average data from 59 locations, iso-wind speed contours are drawn by constructing monthly and yearly maps. The most suitable period for utilizing wind potential is May-August. During this period, the country as a whole exhibits the best wind resource potential, with an average speed of about 3 m/s. (3 m/s average wind speed is very poor for wind power generation). The most promising regions for exploiting wind power throughout the year are the coastline, lower Sind and north-western Balochistan. (author).
A Multi-Functional Power Electronic Converter in Distributed Generation Power Systems
DEFF Research Database (Denmark)
Chen, Zhe; Blaabjerg, Frede; Pedersen, John Kim
2005-01-01
of the converter interfacing a wind power generation unit is also given. The power electronic interface performs the optimal operation in the wind turbine system to extract the maximum wind power, while it also plays a key role in a hybrid compensation system that consists of the active power electronic converter...... and passive filters connected to each distorting load or distributed generation (DG) unit. The passive filters are distributely located to remove major harmonics and provide reactive power compensation. The active power electronic filter corrects the system unbalance, removes the remaining harmonic components......, and damps the possible harmonic resonance. Simulation results demonstrate that the converter system can transfer the real power by following a desired reference power for a variable speed wind power conversion system to effectively extract the renewable energy and also enhance the power quality...
Location Refinement and Power Coverage Analysis Based on Distributed Antenna
Institute of Scientific and Technical Information of China (English)
赵晓楠; 侯春萍; 汪清; 陈华; 浦亮洲
2016-01-01
To establish wireless channel suitable for the cabin environment, the power coverage was investigated with distributed antenna system and centralized antenna system based on the actual measurement of channel im-pulse response. The results indicated that the distributed antenna system has more uniform power coverage than the centralized antenna system. The average relative errors of receiving power of both antennas were calculated. The optimal position of the centralized antenna was obtained by Gaussian function refinement, making the system achieve a better transmission power with the same coverage effect, and providing a reference for antenna location in the future real communication in the cabin.
A study on reliability of power customer in distribution network
Liu, Liyuan; Ouyang, Sen; Chen, Danling; Ma, Shaohua; Wang, Xin
2017-05-01
The existing power supply reliability index system is oriented to power system without considering actual electricity availability in customer side. In addition, it is unable to reflect outage or customer’s equipment shutdown caused by instantaneous interruption and power quality problem. This paper thus makes a systematic study on reliability of power customer. By comparing with power supply reliability, reliability of power customer is defined and extracted its evaluation requirements. An indexes system, consisting of seven customer indexes and two contrast indexes, are designed to describe reliability of power customer from continuity and availability. In order to comprehensively and quantitatively evaluate reliability of power customer in distribution networks, reliability evaluation method is proposed based on improved entropy method and the punishment weighting principle. Practical application has proved that reliability index system and evaluation method for power customer is reasonable and effective.
Tissue distribution of histo-blood group antigens
DEFF Research Database (Denmark)
Ravn, V; Dabelsteen, Erik
2000-01-01
carrier carbohydrate chains. Histo-blood group antigens are found in most epithelial tissues. Meanwhile, several factors influence the type, the amount, and the histological distribution of histoblood group antigens, i.e. the ABO, Lewis, and saliva-secretor type of the individual, and the cell- and tissue......The introduction of immunohistochemical techniques and monoclonal antibodies to specific carbohydrate epitopes has made it possible to study in detail the tissue distribution of histo-blood group antigens and related carbohydrate structures. The present paper summarizes the available data...... concerning the histological distribution of histo-blood group antigens and their precursor structures in normal human tissues. Studies performed have concentrated on carbohydrate antigens related to the ABO, Lewis, and TTn blood group systems, i.e. histo-blood group antigens carried by type 1, 2, and 3 chain...
High-power CSI-fed induction motor drive with optimal power distribution based control
Kwak, S.-S.
2011-11-01
In this article, a current source inverter (CSI) fed induction motor drive with an optimal power distribution control is proposed for high-power applications. The CSI-fed drive is configured with a six-step CSI along with a pulsewidth modulated voltage source inverter (PWM-VSI) and capacitors. Due to the PWM-VSI and the capacitor, sinusoidal motor currents and voltages with high quality as well as natural commutation of the six-step CSI can be obtained. Since this CSI-fed drive can deliver required output power through both the six-step CSI and PWM-VSI, this article shows that the kVA ratings of both the inverters can be reduced by proper real power distribution. The optimal power distribution under load requirements, based on power flow modelling of the CSI-fed drive, is proposed to not only minimise the PWM-VSI rating but also reduce the six-step CSI rating. The dc-link current control of the six-step CSI is developed to realise the optimal power distribution. Furthermore, a vector controlled drive for high-power induction motors is proposed based on the optimal power distribution. Experimental results verify the high-power CSI-fed drive with the optimal power distribution control.
Distributed Control of the Power Supply-Demand Balance
Larsen, Gunn K. H.; van Foreest, Nicky D.; Scherpen, Jacquelien M. A.
2013-01-01
This paper aims to achieve a balance of power in a group of prosumers, based on a price mechanism, i.e., to steer the difference between the total production and consumption of power to zero. We first set the information network topology such that the prosumers exchange price (power) information wit
Power Capability in Low Voltage DC Distribution Systems
Directory of Open Access Journals (Sweden)
C.O. Gecan
2009-12-01
Full Text Available Recent developments in power electronics components enable the use of power electronics in Low Voltage (LV networks. This development makes the model of a Low Voltage Direct Current (LVDC distribution system possible. The technical and economical benefits of this technology make possible the alternative hypothesis of using DC instead of AC distribution systems. Some aspects, such as increasing the capability of the existing lines, interconnecting distributed generation units and even supplying in DC some loads are creating additional requirements of using a LVDC distribution system. The paper presents some general considerations regarding cables used in a LVAC distribution system and different line reconfigurations witch enable the use of cobles in a LVDC distribution system. The reconfigurations are presented in respect of the DC network topologies: unipolar and bipolar. The central aim of this paper is to investigate capability of power transmission and to calculate the transmission distance for cables used in Low Voltage AC and DC distribution systems. Capability computation is considered in respect of two constrains imposed in the cables cross section selection: cable thermal limit and the maximum allowable voltage drop. Cable thermal limit is represented in calculations by the maximum rated current. The equations used to calculate the power capability are presented for single-phase and threephase AC networks and unipolar and bipolar DC networks. Based on these equations, comparisons between power capability of cables with different cross sections used in Low Voltage DC and AC distribution systems are realized and presented.
Shuttle Electrical Power Analysis Program (SEPAP) distribution circuit analysis report
Torina, E. M.
1975-01-01
An analysis and evaluation was made of the operating parameters of the shuttle electrical power distribution circuit under load conditions encountered during a normal Sortie 2 Mission with emphasis on main periods of liftoff and landing.
multichannel distribution meter: a veritable solution in power ...
African Journals Online (AJOL)
eobe
serious effect on power generation, transmission and distribution [5] due to possible ... while a light emitting diode (LED), a light dependent resistor (LDR), and a ... measurement and comparison of voltage or current changes in the meters to ...
Estimating Statistical Power for Open Enrollment Group Treatment Trials
Morgan-Lopez, Antonio A.; Saavedra, Lissette M.; Hien, Denise A.; Fals-Stewart, William
2010-01-01
Modeling turnover in group membership has been identified as a key barrier contributing to a disconnect between the manner in which behavioral treatment is conducted (open enrollment groups) and the designs of substance abuse treatment trials (closed enrollment groups, individual therapy). Latent class pattern mixture models (LCPMM) are an emerging tool for modeling data from open enrollment groups with membership turnover in recently proposed treatment trials. The current article illustrates an approach to conducting power analyses for open enrollment designs based on Monte Carlo simulation of LCPMM models using parameters derived from published data from an RCT comparing Seeking Safety to a Community Care condition for women presenting with comorbid PTSD and substance use disorders. The example addresses discrepancies between the analysis framework assumed in power analyses of many recently-proposed open enrollment trials and the proposed use of LCPMM for data analysis. PMID:20832971
Predictive power of renormalisation group flows a comparison
Litim, Daniel F; Litim, Daniel F.; Pawlowski, Jan M.
2001-01-01
We study a proper-time renormalisation group, which is based on an operator cut-off regularisation of the one-loop effective action. The predictive power of this approach is constrained because the flow is not an exact one. We compare it to the Exact Renormalisation Group, which is based on a momentum regulator in the Wilsonian sense. In contrast to the former, the latter provides an exact flow. To leading order in a derivative expansion, an explicit map from the exact to the proper-time renormalisation group is established. The opposite map does not exist in general. We discuss various implications of these findings, in particular in view of the predictive power of the proper-time renormalisation group. As an application, we compute critical exponents for O(N)-symmetric scalar theories at the Wilson-Fisher fixed point in 3d from both formalisms.
Optimization Criteria for Reactive Power Compensation in Distribution Networks
Directory of Open Access Journals (Sweden)
Waldemar Szpyra
2014-12-01
Full Text Available This paper describes the effects of reactive power flow through the power transmission and distribution networks. It also presents the dependencies allowing calculating the costs and effects of reactive power compensation. Additionally, selected methods for assessing economic efficiency were discussed. The paper presents calculation results for different variants of reactive power compensation in a real, medium voltage feeder. The results indicate that maximum profit from the reduction of losses due to reactive power compensation does not necessarily mean the most efficient solution from the economic point of view.
AC Power Routing System in Home Based on Demand and Supply Utilizing Distributed Power Sources
Directory of Open Access Journals (Sweden)
Takashi Hikihara
2011-04-01
Full Text Available To help reduce consumption of fossil fuels, renewable, natural and distributed power sources are being adopted. These alternative energy sources inevitably show fluctuations in the amount of output power, frequency, and voltage. The suppression of such fluctuations is a key issue to avoid disturbances in power grids. A similar situation arises as far as the regulation of in-home power flow is concerned. We focus on the quality of supplied and demanded power in particular. In this paper, an in-home power distribution system based on information of power is proposed. The system is developed in order to integrate power dispatch and communication. The experimental results show the feasibility of new flexible and efficient power management approaches.
The amenability of the substitution group of formal power series
Energy Technology Data Exchange (ETDEWEB)
Babenko, Ivan K; Bogatyi, Semen A
2011-04-30
We study the amenability property for the group J(k) of formal power series in one variable with coefficients in a commutative ring k with identity. We show that there exists an invariant mean on the space C{sub u}*(J(k)) of uniformly continuous bounded functions on this group. This is equivalent to the fact that every continuous action of J(k) on every compact space has an invariant probability measure.
Power laws in citation distributions: evidence from Scopus.
Brzezinski, Michal
Modeling distributions of citations to scientific papers is crucial for understanding how science develops. However, there is a considerable empirical controversy on which statistical model fits the citation distributions best. This paper is concerned with rigorous empirical detection of power-law behaviour in the distribution of citations received by the most highly cited scientific papers. We have used a large, novel data set on citations to scientific papers published between 1998 and 2002 drawn from Scopus. The power-law model is compared with a number of alternative models using a likelihood ratio test. We have found that the power-law hypothesis is rejected for around half of the Scopus fields of science. For these fields of science, the Yule, power-law with exponential cut-off and log-normal distributions seem to fit the data better than the pure power-law model. On the other hand, when the power-law hypothesis is not rejected, it is usually empirically indistinguishable from most of the alternative models. The pure power-law model seems to be the best model only for the most highly cited papers in "Physics and Astronomy". Overall, our results seem to support theories implying that the most highly cited scientific papers follow the Yule, power-law with exponential cut-off or log-normal distribution. Our findings suggest also that power laws in citation distributions, when present, account only for a very small fraction of the published papers (less than 1 % for most of science fields) and that the power-law scaling parameter (exponent) is substantially higher (from around 3.2 to around 4.7) than found in the older literature.
Power Distribution for the ATLAS LAr Trigger Digitizer Board
Lazzaroni, Massimo; The ATLAS collaboration
2015-01-01
The research activity for the design of the power distribution section of the ATLAS LAr Trigger Digitizer Board board (LTDB) will be presented. Many aspects concerning the radiation hardness and the ability to operate Point-of-load converters even in presence of high magnetic fields will be covered. Devices designed by CERN have been used and their capability for implementation on the ATLAS LTDB has been exploited with the aim to have a power distribution section with the required performances.
Chassin, David P.; Donnelly, Matthew K.; Dagle, Jeffery E.
2006-12-12
Electrical power distribution control methods, electrical energy demand monitoring methods, and power management devices are described. In one aspect, an electrical power distribution control method includes providing electrical energy from an electrical power distribution system, applying the electrical energy to a load, providing a plurality of different values for a threshold at a plurality of moments in time and corresponding to an electrical characteristic of the electrical energy, and adjusting an amount of the electrical energy applied to the load responsive to an electrical characteristic of the electrical energy triggering one of the values of the threshold at the respective moment in time.
A complete data frame work for fitting power law distributions
Gillespie, Colin S
2014-01-01
Over the last few decades power law distributions have been suggested as forming generative mechanisms in a variety of disparate fields, such as, astrophysics, criminology and database curation. However, fitting these heavy tailed distributions requires care, especially since the power law behaviour may only be present in the distributional tail. Current state of the art methods for fitting these models rely on estimating the cut-off parameter $x_{\\min}$. This results in the majority of collected data being discarded. This paper provides an alternative, principled approached for fitting heavy tailed distributions. By directly modelling the deviation from the power law distribution, we can fit and compare a variety of competing models in a single unified framework.
Operation of Modern Distribution Power Systems in Competitive Electricity Markets
DEFF Research Database (Denmark)
Hu, Weihao
In this dissertation, the characteristics of a distribution system under a dynamic electricity-pricing, load management system and under a large number of power electronic interfaced distributed generation units are investigated. The operation characteristics of a power system with wind turbines......, DG units, loads and electricity price are studied. Further, the effect of energy storage systems will be considered, and an optimal operation strategy for energy storage devices in a large scale wind power system in the electricity market is proposed. The western Danish power system, which has large...... penetrations of variable wind power production and may represent the future electricity markets in some ways, is chosen as the studied power system. 10 year actual data from the Danish competitive electricity market are collected and analyzed. The relationship among the electricity price, the consumption...
The effects of transients on photospheric and chromospheric power distributions
Samanta, T; Banerjee, D; Prasad, S Krishna; Mathioudakis, M; Jess, D; Pant, V
2016-01-01
We have observed a quiet Sun region with the Swedish 1-meter Solar Telescope (SST) equipped with CRISP Imaging SpectroPolarimeter. High-resolution, high-cadence, H$\\alpha$ line scanning images were taken to observe different layers of the solar atmosphere from the photosphere to upper chromosphere. We study the distribution of power in different period-bands at different heights. Power maps of the upper photosphere and the lower chromosphere show suppressed power surrounding the magnetic-network elements, known as "magnetic shadows". These also show enhanced power close to the photosphere, traditionally referred to as "power halos". The interaction between acoustic waves and inclined magnetic fields is generally believed to be responsible for these two effects. In this study we explore if small-scale transients can influence the distribution of power at different heights. We show that the presence of transients, like mottles, Rapid Blueshifted Excursions (RBEs) and Rapid Redshifted Excursions (RREs), can stro...
The Power of Opposition Parliamentary Party Groups in European Scrutiny
Holzhacker, Ronald
2005-01-01
This paper investigates the power of opposition parliamentary party groups when scrutinising their governments' decision-making concerning European Union issues, an important component in assuring democracy within the emerging multi-level system of governance in the EU. It first sets out the advanta
Advanced Electric Distribution, Switching, and Conversion Technology for Power Control
Soltis, James V.
1998-01-01
The Electrical Power Control Unit currently under development by Sundstrand Aerospace for use on the Fluids Combustion Facility of the International Space Station is the precursor of modular power distribution and conversion concepts for future spacecraft and aircraft applications. This unit combines modular current-limiting flexible remote power controllers and paralleled power converters into one package. Each unit includes three 1-kW, current-limiting power converter modules designed for a variable-ratio load sharing capability. The flexible remote power controllers can be used in parallel to match load requirements and can be programmed for an initial ON or OFF state on powerup. The unit contains an integral cold plate. The modularity and hybridization of the Electrical Power Control Unit sets the course for future spacecraft electrical power systems, both large and small. In such systems, the basic hybridized converter and flexible remote power controller building blocks could be configured to match power distribution and conversion capabilities to load requirements. In addition, the flexible remote power controllers could be configured in assemblies to feed multiple individual loads and could be used in parallel to meet the specific current requirements of each of those loads. Ultimately, the Electrical Power Control Unit design concept could evolve to a common switch module hybrid, or family of hybrids, for both converter and switchgear applications. By assembling hybrids of a common current rating and voltage class in parallel, researchers could readily adapt these units for multiple applications. The Electrical Power Control Unit concept has the potential to be scaled to larger and smaller ratings for both small and large spacecraft and for aircraft where high-power density, remote power controllers or power converters are required and a common replacement part is desired for multiples of a base current rating.
Power distribution and performance analysis for wireless communication networks
Zhao, Dongmei
2012-01-01
This book provides an analysis of transmission power and network performance in different wireless communication networks. It presents the latest research and techniques for power and interference control and performance modeling in wireless communication networks with different network topologies, air interfaces, and transmission techniques. While studying the power distributions and resource management, the reader will also learn basic methodology and skills for problem formulations, can ascertain the complexity for designing radio resource management strategies in modern wireless communicat
Directory of Open Access Journals (Sweden)
Sébastien Hélie
2007-09-01
Full Text Available This paper presents a graphical way of interpreting effect sizes when more than two groups are involved in a statistical analysis. This method uses noncentral distributions to specify the alternative hypothesis, and the statistical power can thus be directly computed. This principle is illustrated using the chi-squared distribution and the F distribution. Examples of chi-squared and ANOVA statistical tests are provided to further illustrate the point. It is concluded that power analyses are an essential part of statistical analysis, and that using noncentral distributions provides an argument in favour of using a factorial ANOVA over multiple t tests.
A generalization of the power law distribution with nonlinear exponent
Prieto, Faustino; Sarabia, José María
2017-01-01
The power law distribution is usually used to fit data in the upper tail of the distribution. However, commonly it is not valid to model data in all the range. In this paper, we present a new family of distributions, the so-called Generalized Power Law (GPL), which can be useful for modeling data in all the range and possess power law tails. To do that, we model the exponent of the power law using a non-linear function which depends on data and two parameters. Then, we provide some basic properties and some specific models of that new family of distributions. After that, we study a relevant model of the family, with special emphasis on the quantile and hazard functions, and the corresponding estimation and testing methods. Finally, as an empirical evidence, we study how the debt is distributed across municipalities in Spain. We check that power law model is only valid in the upper tail; we show analytically and graphically the competence of the new model with municipal debt data in the whole range; and we compare the new distribution with other well-known distributions including the Lognormal, the Generalized Pareto, the Fisk, the Burr type XII and the Dagum models.
Curseu, Petru Lucian; Sari, Kimzana
2015-01-01
This study sets up to test the extent to which gender variety moderates the impact of power disparity on group cognitive complexity (GCC) and satisfaction with the group in a collaborative learning setting. Using insights from gender differences in perceptions, orientations and conflict handling behavior in negotiation, as well as gender…
SPIDER - IX. Classifying galaxy groups according to their velocity distribution
Ribeiro, A. L. B.; de Carvalho, R. R.; Trevisan, M.; Capelato, H. V.; La Barbera, F.; Lopes, P. A. A.; Schilling, A. C.
2013-09-01
We introduce a new method to study the velocity distribution of galaxy systems, the Hellinger Distance (HD), designed for detecting departures from a Gaussian velocity distribution. Testing different approaches to measure normality of a distribution, we conclude that HD is the least vulnerable method to type I and II statistical errors. We define a relaxed galactic system as the one with unimodal velocity distribution and a normality deviation below a critical value (HD ) and the Gaussianity of the velocity distribution of the groups. Bright galaxies (Mr ≤ -20.7) residing in the inner and outer regions of groups do not show significant differences in the listed quantities regardless if the group has a Gaussian (G) or a Non-Gaussian (NG) velocity distribution. However, the situation is significantly different when we examine the faint galaxies (-20.7 < Mr ≤ -17.9). In G groups, there is a remarkable difference between the galaxy properties of the inner and outer galaxy populations, testifying how the environment is affecting the galaxies. Instead, in NG groups there is no segregation between the properties of galaxies in the inner and outer regions, showing that the properties of these galaxies still reflect the physical processes prevailing in the environment where they were found earlier.
Load flow computations in hybrid transmission - distributed power systems
Wobbes, E.D.; Lahaye, D.J.P.
2013-01-01
We interconnect transmission and distribution power systems and perform load flow computations in the hybrid network. In the largest example we managed to build, fifty copies of a distribution network consisting of fifteen nodes is connected to the UCTE study model, resulting in a system consisting
Sensitivity of the power distribution in large heterogeneous LMFBR designs
Energy Technology Data Exchange (ETDEWEB)
Tzanos, C.P.; Barthold, W.P.
1977-01-01
In heterogeneous LMFBR designs consisting of consecutive core and blanket zones, the power distribution is very sensitive to enrichment distribution changes in the core zones. The purpose of the paper is to analyze this sensitivity in heterogeneous LMFBR designs of different degrees of coupling among the core zones.
Area and Flux Distributions of Active Regions, Sunspot Groups, and Sunspots: A Multi-Database Study
Muñoz-Jaramillo, Andrés; Windmueller, John C; Amouzou, Ernest C; Longcope, Dana W; Tlatov, Andrey G; Nagovitsyn, Yury A; Pevtsov, Alexei A; Chapman, Gary A; Cookson, Angela M; Yeates, Anthony R; Watson, Fraser T; Balmaceda, Laura A; DeLuca, Edward E; Martens, Petrus C H
2014-01-01
In this work we take advantage of eleven different sunspot group, sunspot, and active region databases to characterize the area and flux distributions of photospheric magnetic structures. We find that, when taken separately, different databases are better fitted by different distributions (as has been reported previously in the literature). However, we find that all our databases can be reconciled by the simple application of a proportionality constant, and that, in reality, different databases are sampling different parts of a composite distribution. This composite distribution is made up by linear combination of Weibull and log-normal distributions -- where a pure Weibull (log-normal) characterizes the distribution of structures with fluxes below (above) $10^{21}$Mx ($10^{22}$Mx). Additionally, we demonstrate that the Weibull distribution shows the expected linear behaviour of a power-law distribution (when extended into smaller fluxes), making our results compatible with the results of Parnell et al.\\ (200...
Groups versus individuals in the determination of caribou distribution
Directory of Open Access Journals (Sweden)
K. R. Whitten
1986-06-01
Full Text Available Studies of caribou (Rangifer tarandus habitat selection based on group analyses have led to erroneous conclusions. Convenient designations such as «male-» or «female-dominated» group encompass a wide array of possible sizes and compositions which change continuously and erratically. Whenever individuals of at particular sex/age class can occur in more than one group type, and/or whenever groups within a type vary in size, an analysis based on groups alone is fallacious. Data must be based on individual caribou for most, if not all, determinations of distribution.
Distribution of phytoplankton groups within the deep chlorophyll maximum
Latasa, Mikel
2016-11-01
The fine vertical distribution of phytoplankton groups within the deep chlorophyll maximum (DCM) was studied in the NE Atlantic during summer stratification. A simple but unconventional sampling strategy allowed examining the vertical structure with ca. 2 m resolution. The distribution of Prochlorococcus, Synechococcus, chlorophytes, pelagophytes, small prymnesiophytes, coccolithophores, diatoms, and dinoflagellates was investigated with a combination of pigment-markers, flow cytometry and optical and FISH microscopy. All groups presented minimum abundances at the surface and a maximum in the DCM layer. The cell distribution was not vertically symmetrical around the DCM peak and cells tended to accumulate in the upper part of the DCM layer. The more symmetrical distribution of chlorophyll than cells around the DCM peak was due to the increase of pigment per cell with depth. We found a vertical alignment of phytoplankton groups within the DCM layer indicating preferences for different ecological niches in a layer with strong gradients of light and nutrients. Prochlorococcus occupied the shallowest and diatoms the deepest layers. Dinoflagellates, Synechococcus and small prymnesiophytes preferred shallow DCM layers, and coccolithophores, chlorophytes and pelagophytes showed a preference for deep layers. Cell size within groups changed with depth in a pattern related to their mean size: the cell volume of the smallest group increased the most with depth while the cell volume of the largest group decreased the most. The vertical alignment of phytoplankton groups confirms that the DCM is not a homogeneous entity and indicates groups’ preferences for different ecological niches within this layer.
When Inequality Fails: Power, Group Dominance, and Societal Change
Directory of Open Access Journals (Sweden)
Felicia Pratto
2013-12-01
Full Text Available Social dominance theory was developed to account for why societies producing surplus take and maintain the form of group-based dominance hierarchies, in which at least one socially-constructed group has more power than another, and in which men are more powerful than women and adults more powerful than children. Although the theory has always allowed for societies to differ in their severity of group-based dominance and how it is implemented, it has predicted that alternative forms of societal organization will occur rarely and not last. This paper revisits aspects of the theory that allow for the possibility of societal alternatives and change. We also consider boundary conditions for the theory, and whether its current theoretical apparatus can account for societal change. By expanding the typical three-level dynamic system to describe societies (micro-meso-macro into four levels (including meta to consider how societies relate to one another, we identify political tensions that are unstable power structures rather than stable hierarchies. In research on institutions, we identify smaller-scale alternative forms of social organization. We identify logical, empirical, and theoretical shortcomings in social dominance theory’s account of stability and change, consider alternative forms of social organization, and suggest fruitful avenues for theoretical extension.
Autonomous Active and Reactive Power Distribution Strategy in Islanded Microgrids
DEFF Research Database (Denmark)
Wu, Dan; Tang, Fen; Guerrero, Josep M.;
2014-01-01
This paper proposes an autonomous active and reactive power distribution strategy that can be applied directly on current control mode (CCM) inverters, being compatible as well with conventional droop-controlled voltage control mode (VCM) converters. In a microgrid, since renewable energy sources...... in a distributed way. Real-time hardware-in-the-loop results are presented to verify the proposed control strategy.......This paper proposes an autonomous active and reactive power distribution strategy that can be applied directly on current control mode (CCM) inverters, being compatible as well with conventional droop-controlled voltage control mode (VCM) converters. In a microgrid, since renewable energy sources...
Directory of Open Access Journals (Sweden)
Shan Yang
2016-01-01
Full Text Available Power flow calculation and short circuit calculation are the basis of theoretical research for distribution network with inverter based distributed generation. The similarity of equivalent model for inverter based distributed generation during normal and fault conditions of distribution network and the differences between power flow and short circuit calculation are analyzed in this paper. Then an integrated power flow and short circuit calculation method for distribution network with inverter based distributed generation is proposed. The proposed method let the inverter based distributed generation be equivalent to Iθ bus, which makes it suitable to calculate the power flow of distribution network with a current limited inverter based distributed generation. And the low voltage ride through capability of inverter based distributed generation can be considered as well in this paper. Finally, some tests of power flow and short circuit current calculation are performed on a 33-bus distribution network. The calculated results from the proposed method in this paper are contrasted with those by the traditional method and the simulation method, whose results have verified the effectiveness of the integrated method suggested in this paper.
Agent Based Control of Electric Power Systems with Distributed Generation
DEFF Research Database (Denmark)
Saleem, Arshad
. Situation in Denmark is even more interesting, with a current 20% penetration of wind energy it is moving towards an ambitious goal of 50% penetration by the year 2050. Realization of these concepts requires that power systems should be of distributed nature { consisting of autonomous components...... agents. It suggests a multiagent based exible control architecture (subgrid control) suitable for the implementation of the innovative control concepts. This subgrid control architecture is tested on a novel distributed software platform which has been developed to design, test and evaluate distributed...... control strategies. The results have been discussed from case studies of multiagent based distributed control scenarios in electric power systems. The main contribution of this work is a proposal for system design methodology for application of intelligent agent technology in power systems...
Competition and Cooperation of Distributed Generation and Power System
Miyake, Masatoshi; Nanahara, Toshiya
Advances in distributed generation technologies together with the deregulation of an electric power industry can lead to a massive introduction of distributed generation. Since most of distributed generation will be interconnected to a power system, coordination and competition between distributed generators and large-scale power sources would be a vital issue in realizing a more desirable energy system in the future. This paper analyzes competitions between electric utilities and cogenerators from the viewpoints of economic and energy efficiency based on the simulation results on an energy system including a cogeneration system. First, we examine best response correspondence of an electric utility and a cogenerator with a noncooperative game approach: we obtain a Nash equilibrium point. Secondly, we examine the optimum strategy that attains the highest social surplus and the highest energy efficiency through global optimization.
Operation of Modern Distribution Power Systems in Competitive Electricity Markets
DEFF Research Database (Denmark)
Hu, Weihao
strategy for trading wind power in the Danish short-term electricity market in order to minimize the imbalance costs for regulation. A load optimization method based on spot price for demand side management in Denmark is proposed in order to save the energy costs for 3 types of typical Danish consumers......In this dissertation, the characteristics of a distribution system under a dynamic electricity-pricing, load management system and under a large number of power electronic interfaced distributed generation units are investigated. The operation characteristics of a power system with wind turbines...... penetrations of variable wind power production and may represent the future electricity markets in some ways, is chosen as the studied power system. 10 year actual data from the Danish competitive electricity market are collected and analyzed. The relationship among the electricity price, the consumption...
An Effective Distributed Model for Power System Transient Stability Analysis
Directory of Open Access Journals (Sweden)
MUTHU, B. M.
2011-08-01
Full Text Available The modern power systems consist of many interconnected synchronous generators having different inertia constants, connected with large transmission network and ever increasing demand for power exchange. The size of the power system grows exponentially due to increase in power demand. The data required for various power system applications have been stored in different formats in a heterogeneous environment. The power system applications themselves have been developed and deployed in different platforms and language paradigms. Interoperability between power system applications becomes a major issue because of the heterogeneous nature. The main aim of the paper is to develop a generalized distributed model for carrying out power system stability analysis. The more flexible and loosely coupled JAX-RPC model has been developed for representing transient stability analysis in large interconnected power systems. The proposed model includes Pre-Fault, During-Fault, Post-Fault and Swing Curve services which are accessible to the remote power system clients when the system is subjected to large disturbances. A generalized XML based model for data representation has also been proposed for exchanging data in order to enhance the interoperability between legacy power system applications. The performance measure, Round Trip Time (RTT is estimated for different power systems using the proposed JAX-RPC model and compared with the results obtained using traditional client-server and Java RMI models.
Group performance is maximized by hierarchical competence distribution
Zafeiris, Anna
2013-01-01
Groups of people or even robots often face problems they need to solve together. Examples include collectively searching for resources, choosing when and where to invest time and effort, and many more. Although a hierarchical ordering of the relevance of the group members' inputs during collective decision making is abundant, a quantitative demonstration of its origin and advantages using a generic approach has not been described yet. Here we introduce a family of models based on the most general features of group decision making to show that the optimal distribution of competences is a highly skewed function with a structured fat tail. Our results have been obtained by optimizing the groups' compositions through identifying the best performing distributions for both the competences and for the members' flexibilities/pliancies. Potential applications include choosing the best composition for a group intended to solve a given task.
Optimal Operation of Energy Storage in Power Transmission and Distribution
Akhavan Hejazi, Seyed Hossein
In this thesis, we investigate optimal operation of energy storage units in power transmission and distribution grids. At transmission level, we investigate the problem where an investor-owned independently-operated energy storage system seeks to offer energy and ancillary services in the day-ahead and real-time markets. We specifically consider the case where a significant portion of the power generated in the grid is from renewable energy resources and there exists significant uncertainty in system operation. In this regard, we formulate a stochastic programming framework to choose optimal energy and reserve bids for the storage units that takes into account the fluctuating nature of the market prices due to the randomness in the renewable power generation availability. At distribution level, we develop a comprehensive data set to model various stochastic factors on power distribution networks, with focus on networks that have high penetration of electric vehicle charging load and distributed renewable generation. Furthermore, we develop a data-driven stochastic model for energy storage operation at distribution level, where the distribution of nodal voltage and line power flow are modelled as stochastic functions of the energy storage unit's charge and discharge schedules. In particular, we develop new closed-form stochastic models for such key operational parameters in the system. Our approach is analytical and allows formulating tractable optimization problems. Yet, it does not involve any restricting assumption on the distribution of random parameters, hence, it results in accurate modeling of uncertainties. By considering the specific characteristics of random variables, such as their statistical dependencies and often irregularly-shaped probability distributions, we propose a non-parametric chance-constrained optimization approach to operate and plan energy storage units in power distribution girds. In the proposed stochastic optimization, we consider
The process group approach to reliable distributed computing
Birman, Kenneth P.
1992-01-01
The difficulty of developing reliable distribution software is an impediment to applying distributed computing technology in many settings. Experience with the ISIS system suggests that a structured approach based on virtually synchronous process groups yields systems that are substantially easier to develop, exploit sophisticated forms of cooperative computation, and achieve high reliability. Six years of research on ISIS, describing the model, its implementation challenges, and the types of applications to which ISIS has been applied are reviewed.
Group choice: the ideal free distribution of human social behavior.
Kraft, J R; Baum, W M
2001-07-01
Group choice refers to the distribution of group members between two choice alternatives over time. The ideal free distribution (IFD), an optimal foraging model from behavioral ecology, predicts that the ratio of foragers at two resource sites should equal the ratio of obtained resources, a prediction that is formally analogous to the matching law of individual choice, except that group choice is a social phenomenon. Two experiments investigated the usefulness of IFD analyses of human group choice and individual-based explanations that might account for the group-level events. Instead of nonhuman animals foraging at two sites for resources, a group of humans chose blue and red cards to receive points that could earn cash prizes. The groups chose blue and red cards in ratios in positive relation to the ratios of points associated with the cards. When group choice ratios and point ratios were plotted on logarithmic coordinates and fitted with regression lines, the slopes (i.e., sensitivity measures) approached 1.0 but tended to fall short of it (i.e., undermatching), with little bias and little unaccounted for variance. These experiments demonstrate that an IFD analysis of group choice is possible and useful, and suggest that group choice may be explained by the individual members' tendency to optimize reinforcement.
Site selection of active damper for stabilizing power electronics based power distribution system
DEFF Research Database (Denmark)
Yoon, Changwoo; Wang, Xiongfei; Bak, Claus Leth
2015-01-01
Stability in the nowadays distribution power system is endangered by interaction problems that may arise from newly added power-electronics based power devices. Recently, a new concept to deal with this higher frequency instability, the active damper, has been proposed. The active damper is a power...... electronics based power device, which provides an adjustable damping capability to the power system where the voltage harmonic instability is measured. It can stabilize by adjusting the equivalent node impedance with its plug and play feature. This feature gives many degrees of freedom of its installation...... point when the system has many nodes. Therefore, this paper addresses the proper placement of an active damper in an unstable small-scale power distribution system. A time-domain model of the Cigre benchmark low-vltage network is used as a test field. The result shows the active damper location...
Positive laws on generators in powerful pro-p groups
Acciarri, Cristina
2011-01-01
If G is a finitely generated powerful pro-p group satisfying a certain law v=1, and if G can be generated by a normal subset T of finite width which satisfies a positive law, we prove that G is nilpotent. Furthermore, the nilpotency class of G can be bounded in terms of the prime p, the number of generators of G, the law v=1, the width of T, and the degree of the positive law. The main interest of this result is the application to verbal subgroups: if G is a p-adic analytic pro-p group in which all values of a word w satisfy positive law, and if the verbal subgroup w(G) is powerful, then w(G) is nilpotent.
Power laws in citation distributions: Evidence from Scopus
Brzezinski, Michal
2014-01-01
Modeling distributions of citations to scientific papers is crucial for understanding how science develops. However, there is a considerable empirical controversy on which statistical model fits the citation distributions best. This paper is concerned with rigorous empirical detection of power-law behaviour in the distribution of citations received by the most highly cited scientific papers. We have used a large, novel data set on citations to scientific papers published between 1998 and 2002 drawn from Scopus. The power-law model is compared with a number of alternative models using a likelihood ratio test. We have found that the power-law hypothesis is rejected for around half of the Scopus fields of science. For these fields of science, the Yule, power-law with exponential cut-off and log-normal distributions seem to fit the data better than the pure power-law model. On the other hand, when the power-law hypothesis is not rejected, it is usually empirically indistinguishable from most of the alternative mo...
Power dissipation and temperature distribution in piezoelectric ceramic slabs.
Thomas, D; Ebenezer, D D; Srinivasan, Sivakumar M
2010-10-01
A method is presented to determine power dissipation in one-dimensional piezoelectric slabs with internal losses and the resulting temperature distribution. The length of the slab is much greater than the lateral dimensions. Losses are represented using complex piezoelectric coefficients. It is shown that the spatially non-uniform power dissipation density in the slab can be determined by considering either hysteresis loops or the Poynting vector. The total power dissipated in the slab is obtained by integrating the power dissipation density over the slab and is shown to be equal to the power input to the slab for special cases of mechanically and electrically excited slabs. The one-dimensional heat equation that includes the effect of conduction and convection, and the boundary conditions, are then used to determine the temperature distribution. When the analytical expression for the power dissipation density is simple, direct integration is used. It is shown that a modified Fourier series approach yields the same results. For other cases, the temperature distribution is determined using only the latter approach. Numerical results are presented to illustrate the effects of internal losses, heat conduction and convection coefficients, and boundary conditions on the temperature distribution.
Power Quality Analysis Using Bilinear Time-Frequency Distributions
Directory of Open Access Journals (Sweden)
Sha'ameri AhmadZuri
2010-01-01
Full Text Available Abstract Bilinear time-frequency distributions (TFDs are powerful techniques that offer good time and frequency resolution of time-frequency representation (TFR. It is very appropriate to analyze power quality signals which consist of nonstationary and multi-frequency components. However, the TFDs suffer from interference because of cross-terms. Many TFDs have been implemented, and there is no fixed window or kernel that can remove the cross-terms for all types of signals. In this paper, the bilinear TFDs are implemented to analyze power quality signals such as smooth-windowed Wigner-Ville distribution (SWWVD, Choi-Williams distribution (CWD, B-distribution (BD, and modified B-distribution (MBD. The power quality signals focused are swell, sag, interruption, harmonic, interharmonic, and transient based on IEEE Std, 1159-1995. A set of performance measures is defined and used to compare the TFRs. It shows that SWWVD presents the best performance and is selected for power quality signal analysis. Thus, an adaptive optimal kernel SWWVD is designed to determine the separable kernel automatically from the input signal.
Energy Technology Data Exchange (ETDEWEB)
Ezure, Hideo
1988-09-01
Effective combination of measured data with theoretical analysis has permitted deriving a mehtod for more accurately estimating the power distribution in BWRs. Use is made of least squares method for the combination between relationship of the power distribution with measured values and the model used in FLARE or in the three-dimensional two-group diffusion code. Trial application of the new method to estimating the power distribution in JPDR-1 has proved the method to provide reliable results.
Enhancement of Distributed Generation by Using Custom Power Device
Institute of Scientific and Technical Information of China (English)
Kishor V. Bhadane; M. S. Ballal; R. M. Moharil
2015-01-01
Abstract-Wind energy (WE) has become immensely popular for distributed generation (DG). This case presents the monitoring, modeling, control, and analysis of the two-level three-phase WE based DG system where the electric grid interfacing custom power device (CPD) is controlled to perform the smart exchanging of electric power as per the Indian grid code. WE is connected to DC link of CPD for the grid integration purpose. The CPD based distributed static compensator, i.e. the distributed static synchronous compensator (DSTATCOM), is utilized for injecting the wind power to the point of common coupling (PCC) and also acts against the reactive power demand. The novel indirect current control scheme of DSTATCOM regulates the power import and export between the WE and the electric grid system. It also acts as a compensator and performs both the key features simultaneously. Hence, the penetration of additional generated WE power to the grid is increased by 20% to 25%. The burden of reactive power compensation from grid is reduced by DSTATCOM. The modeling and simulation are done in MATLAB. The results are validated and verified.
Comparison of Wind Power and Load Forecasting Error Distributions: Preprint
Energy Technology Data Exchange (ETDEWEB)
Hodge, B. M.; Florita, A.; Orwig, K.; Lew, D.; Milligan, M.
2012-07-01
The introduction of large amounts of variable and uncertain power sources, such as wind power, into the electricity grid presents a number of challenges for system operations. One issue involves the uncertainty associated with scheduling power that wind will supply in future timeframes. However, this is not an entirely new challenge; load is also variable and uncertain, and is strongly influenced by weather patterns. In this work we make a comparison between the day-ahead forecasting errors encountered in wind power forecasting and load forecasting. The study examines the distribution of errors from operational forecasting systems in two different Independent System Operator (ISO) regions for both wind power and load forecasts at the day-ahead timeframe. The day-ahead timescale is critical in power system operations because it serves the unit commitment function for slow-starting conventional generators.
2010-05-26
.... EL10-68-000] Resale Power Group of Iowa, WPPI Energy v. ITC Midwest LLC, Interstate Power and Light...), and section 306 of the Federal Power Act, 16 U.S.C. 825(e) (2006), Resale Power Group of Iowa and WPPI Energy (Complainants) filed a formal complaint against ITC Midwest LLC and Interstate Power and...
Edge effect on the power law distribution of granular avalanches.
Lorincz, Kinga A; Wijngaarden, Rinke J
2007-10-01
Many punctuated phenomena in nature are claimed [e.g., by the theory of self-organized criticality (SOC)] to be power-law distributed. In our experiments on a three-dimensional pile of long-grained rice, we find that by only changing the boundary condition of the system, we switch from such power-law-distributed avalanche sizes to quasiperiodic system-spanning avalanches. Conversely, by removing ledges the incidence of system-spanning avalanches is significantly reduced. This may offer a perspective on new avalanche prevention schemes. In addition, our findings may help to explain why the archetype of SOC, the sandpile, was found to have power-law-distributed avalanches in some experiments, while in other experiments quasiperiodic system-spanning avalanches were found.
Distributed control for optimal reactive power compensation in smart microgrids
Bolognani, Saverio
2011-01-01
We consider the problem of optimal reactive power compensation for the minimization of power distribution losses in a smart microgrid. We first propose an approximate model for the power distribution network, which allows us to cast the problem into the class of convex quadratic, linearly constrained, optimization problems. We also show how this model provides the tools for a distributed approach, in which agents have a partial knowledge of the problem parameters and state, and can only perform local measurements. Then, we design a randomized, gossip-like optimization algorithm, providing conditions for convergence together with an analytic characterization of the convergence speed. The analysis shows that the best performance can be achieved when we command cooperation among agents that are neighbors in the smart microgrid topology. Numerical simulations are included to validate the proposed model and to confirm the analytic results about the performance of the proposed algorithm.
Data Collection for Mobile Group Consumption: An Asynchronous Distributed Approach.
Zhu, Weiping; Chen, Weiran; Hu, Zhejie; Li, Zuoyou; Liang, Yue; Chen, Jiaojiao
2016-04-06
Mobile group consumption refers to consumption by a group of people, such as a couple, a family, colleagues and friends, based on mobile communications. It differs from consumption only involving individuals, because of the complex relations among group members. Existing data collection systems for mobile group consumption are centralized, which has the disadvantages of being a performance bottleneck, having single-point failure and increasing business and security risks. Moreover, these data collection systems are based on a synchronized clock, which is often unrealistic because of hardware constraints, privacy concerns or synchronization cost. In this paper, we propose the first asynchronous distributed approach to collecting data generated by mobile group consumption. We formally built a system model thereof based on asynchronous distributed communication. We then designed a simulation system for the model for which we propose a three-layer solution framework. After that, we describe how to detect the causality relation of two/three gathering events that happened in the system based on the collected data. Various definitions of causality relations based on asynchronous distributed communication are supported. Extensive simulation results show that the proposed approach is effective for data collection relating to mobile group consumption.
Performance study on Gossip-based group key distribution protocal
Institute of Scientific and Technical Information of China (English)
Yao Yan; Ma Jiaqing; Zhong Yiping; Zhang Shiyong
2006-01-01
Group key distribution is faced with two important problems, i.e. reliability and scalability, to support security multicast for large and dynamic groups. With group member increasing, traditional reliable multicast protocol can not deal with them fully. Gossip-based group key distribution idea for wide-area dissemination was provided. It is based on an gossip-based loss recovery control mechanism. It can provide a probabilistic reliable guarantee for a information dissemination to reach every group member, which can achieve scalability and reliability. To achieve full reliability, three layers protocol model in group key distribution was provided. One is best effect layer, which provides unreliable dissemination. Other is gossip-based loss recovery layer, which provides probabilistic reliable guarantee. Last is vsync-based layer, which provide deterministic loss recovery. We integrate probabilistic loss recovery method with deterministic one. The model possess scalability that probabilistic method has and full reliability prosthesis by vsync-based. To evaluate the effectiveness of gossip technique in scalable and reliable multicast protocols. We have compared gossip protocol with other reliable multicast protocols. Experimental result shows that gossip protocol has better scalability than other.
Silicon Carbide Based Power Mangement and Distribution for Space Nuclear Power Systems Project
National Aeronautics and Space Administration — In this SBIR project, APEI, Inc. is proposing to develop a high efficiency, rad-hard, 100's kWe power management and distribution (PMAD) system for space nuclear...
Power-law distributions in binned empirical data
Virkar, Yogesh
2012-01-01
Many man-made and natural phenomena, including the intensity of earthquakes, population of cities, and size of international wars, are believed to follow power-law distributions. The accurate identification of power-law patterns has significant consequences for developing an understanding of complex systems. However, statistical evidence for or against the power-law hypothesis is complicated by large fluctuations in the empirical distribution's tail, and these are worsened when information is lost from binning the data. We adapt the statistically principled framework for testing the power-law hypothesis, developed by Clauset, Shalizi and Newman, to the case of binned data. This approach includes maximum-likelihood fitting, a hypothesis test based on the Kolmogorov-Smirnov goodness-of-fit statistic and likelihood ratio tests for comparing against alternative explanations. We evaluate the effectiveness of these methods on synthetic binned data with known structure and apply them to twelve real-world binned data...
Radiated power distributions in impurity-seeded plasmas in LHD
Energy Technology Data Exchange (ETDEWEB)
Morisaki, T., E-mail: morisaki@nifs.ac.jp [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Nagoya University, Nagoya 464-8602 (Japan); Oyama, K. [Nagoya University, Nagoya 464-8602 (Japan); Tamura, N.; Masuzaki, S.; Akiyama, T.; Motojima, G.; Miyazawa, J.; Peterson, B.J. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Ohno, N. [Nagoya University, Nagoya 464-8602 (Japan); Yamada, H. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan)
2015-08-15
In LHD, impurity seeding has been performed to enhance the radiative cooling in the edge region. Neon, nitrogen and argon were seeded by gas puffing, and the behaviour of those impurities in the plasma was investigated with the innovative diagnostic method. Two bolometer arrays were used to measure the two-dimensional radiated power distribution. Using the tomographic technique, radiated power distributions on a poloidal plane can be obtained with the high time resolution. During the discharge with neon puff, considerable radiation from the core region was observed, in addition to the strong edge radiation. In spite of the highly radiated power, plasma did not result in the radiation collapse. On the other hand, in the nitrogen-seeded discharge, the strong radiation only from the peripheral region was observed. Different time evolutions of the total radiated power between neon and nitrogen seeded discharges were observed after stopping each impurity puff.
Beach, R. F.; Kimnach, G. L.; Jett, T. A.; Trash, L. M.
1989-01-01
The Lewis Research Center's Power Management and Distribution (PMAD) System testbed and its use in the evaluation of control concepts applicable to the NASA Space Station Freedom electric power system (EPS) are described. The facility was constructed to allow testing of control hardware and software in an environment functionally similar to the space station electric power system. Control hardware and software have been developed to allow operation of the testbed power system in a manner similar to a supervisory control and data acquisition (SCADA) system employed by utility power systems for control. The system hardware and software are described.
Energy storage system control strategies for power distribution systems
Areewan Kajorndech; Dulpichet Rerkpreedapong
2015-01-01
Energy storage systems have been widely employed to attain several benefits, such as reliability improvement, stabilization of power systems connected with renewable energy resources, economic benefits and etc. To achieve the above objectives, the appropriate and effective control strategies for energy storage systems are needed to be developed. This research proposes energy storage system control strategies for power distribution systems equipped with a limited size of energy storage system ...
System-wide power management control via clock distribution network
Energy Technology Data Exchange (ETDEWEB)
Coteus, Paul W.; Gara, Alan; Gooding, Thomas M.; Haring, Rudolf A.; Kopcsay, Gerard V.; Liebsch, Thomas A.; Reed, Don D.
2015-05-19
An apparatus, method and computer program product for automatically controlling power dissipation of a parallel computing system that includes a plurality of processors. A computing device issues a command to the parallel computing system. A clock pulse-width modulator encodes the command in a system clock signal to be distributed to the plurality of processors. The plurality of processors in the parallel computing system receive the system clock signal including the encoded command, and adjusts power dissipation according to the encoded command.
Electrical Power Distribution and Control Modeling and Analysis
Fu, Johnny S.; Liffring, Mark; Mehdi, Ishaque S.
2001-01-01
This slide presentation reviews the use of Electrical Power Distribution and Control (EPD&C) Modeling and how modeling can support analysis. The presentation discusses using the EASY5 model to simulate and analyze the Space Shuttle Electric Auxiliary Power Unit. Diagrams of the model schematics are included, as well as graphs of the battery cell impedance, hydraulic load dynamics, and EPD&C response to hydraulic load variations.
Optimal Operation of Energy Storage in Power Transmission and Distribution
2015-01-01
In this thesis, we investigate optimal operation of energy storage units in power transmission and distribution grids. At transmission level, we investigate the problem where an investor-owned independently-operated energy storage system seeks to offer energy and ancillary services in the day-ahead and real-time markets. We specifically consider the case where a significant portion of the power generated in the grid is from renewable energy resources and there exists significant uncertainty i...
ASYMPTOTIC PROPERTIES OF MLE FOR WEIBULL DISTRIBUTION WITH GROUPED DATA
Institute of Scientific and Technical Information of China (English)
XUE Hongqi; SONG Lixin
2002-01-01
A grouped data model for Weibull distribution is considered. Under mild con-ditions, the maximum likelihood estimators(MLE) are shown to be identifiable, strongly consistent, asymptotically normal, and satisfy the law of iterated logarithm. Newton iter- ation algorithm is also considered, which converges to the unique solution of the likelihood equation. Moreover, we extend these results to a random case.
Power quality improvement of unbalanced power system with distributed generation units
DEFF Research Database (Denmark)
Hu, Y.; Chen, Zhe; Excell, P.
2011-01-01
This paper presents a power electronic system for improving the power quality of the unbalanced distributed generation units in three-phase four-wire system. In the system, small renewable power generation units, such as small PV generator, small wind turbines may be configured as single phase...... generation units. The random nature of renewable power sources may result in significant unbalance in the power network and affect the power quality. An electronic converter system is proposed to correct the system unbalance and harmonics so as to deal with the power quality problems. The operation...... and control of the converter are described. Simulation results have demonstrated that the system can effectively correct the unbalance and enhance the system power quality....
Power-Law Tail in the Chinese Wealth Distribution
Institute of Scientific and Technical Information of China (English)
DING Ning; WANG You-Gui
2007-01-01
@@ We analyse the data from the recently published lists of the richest Chinese from the year 2003 to 2005. The results confirm that in these years the wealth is distributed according to a power law with exponents between 1.758 and 2.285 in the high end. The power distribution is found to be quite robust although the persons in the list change drastically and the wealth increases rapidly. The relation between the wealth and the absolute change of wealth rejects the notion that the wealth evolution is a multiplicative stochastic process.
Synchronization Methods for Three Phase Distributed Power Generation Systems
DEFF Research Database (Denmark)
Timbus, Adrian Vasile; Teodorescu, Remus; Blaabjerg, Frede
2005-01-01
Nowadays, it is a general trend to increase the electricity production using Distributed Power Generation Systems (DPGS) based on renewable energy resources such as wind, sun or hydrogen. If these systems are not properly controlled, their connection to the utility network can generate problems...... on the grid side. Therefore, considerations about power generation, safe running and grid synchronization must be done before connecting these systems to the utility network. This paper is mainly dealing with the grid synchronization issues of distributed systems. An overview of the synchronization methods...
Power Distribution for the ATLAS LAr Trigger Digitizer Board
Lazzaroni, Massimo; The ATLAS collaboration; Latorre, Stefano
2015-01-01
The R&D activity for the design of the power distribution section of the ATLAS Liquid Argon (LAr) Calorimeter Trigger Digitizer Board board (LTDB) is presented. Many aspects concerning the radiation hardness and the ability to operate of Point-of-load converters also in presence of high magnetic fields are covered. Devices designed by CERN, designed for experiments at LHC, have been used and their capability for implementation in the LTDB has been exploited with the aim to have a power distribution section with the required performances.
Convex relaxation of Optimal Power Flow in Distribution Feeders with embedded solar power
DEFF Research Database (Denmark)
Hermann, Alexander Niels August; Wu, Qiuwei; Huang, Shaojun
2016-01-01
panels with uncontrolled inverters, the upper limit of installable capacity is quickly reached in many of today’s distribution feeders. This problem can often be mitigated by optimally controlling the voltage angles of inverters. However, the optimal power flow problem in its standard form is a large......There is an increasing interest in using Distributed Energy Resources (DER) directly coupled to end user distribution feeders. This poses an array of challenges because most of today’s distribution feeders are designed for unidirectional power flow. Therefore when installing DERs such as solar...... scale non-convex optimization problem, and thus can’t be solved precisely and also is computationally heavy and intractable for large systems. This paper examines the use of a convex relaxation using Semi-definite programming to optimally control solar power inverters in a distribution grid in order...
Thresholded Power Law Size Distributions of Instabilities in Astrophysics
Aschwanden, Markus J
2015-01-01
Power law-like size distributions are ubiquitous in astrophysical instabilities. There are at least four natural effects that cause deviations from ideal power law size distributions, which we model here in a generalized way: (1) a physical threshold of an instability; (2) incomplete sampling of the smallest events below a threshold $x_0$; (3) contamination by an event-unrelated background $x_b$; and (4) truncation effects at the largest events due to a finite system size. These effects can be modeled in simplest terms with a "thresholded power law" distribution function (also called generalized Pareto [type II] or Lomax distribution), $N(x) dx \\propto (x+x_0)^{-a} dx$, where $x_0 > 0$ is positive for a threshold effect, while $x_0 < 0$ is negative for background contamination. We analytically derive the functional shape of this thresholded power law distribution function from an exponential-growth evolution model, which produces avalanches only when a disturbance exceeds a critical threshold $x_0$. We app...
Jafarian, Matin; Scherpen, Jacquelien M.A.; Aiello, Marco
2016-01-01
We present a price-based approach to deal with the challenges of the electrical power distribution systems with renewable generations. In specific, we address the power loss minimization and voltage regulation taking into account the actual grid capacity. Analogously, the cost function is reformulat
Distribution-Agnostic Stochastic Optimal Power Flow for Distribution Grids: Preprint
Energy Technology Data Exchange (ETDEWEB)
Baker, Kyri; Dall' Anese, Emiliano; Summers, Tyler
2016-09-01
This paper outlines a data-driven, distributionally robust approach to solve chance-constrained AC optimal power flow problems in distribution networks. Uncertain forecasts for loads and power generated by photovoltaic (PV) systems are considered, with the goal of minimizing PV curtailment while meeting power flow and voltage regulation constraints. A data- driven approach is utilized to develop a distributionally robust conservative convex approximation of the chance-constraints; particularly, the mean and covariance matrix of the forecast errors are updated online, and leveraged to enforce voltage regulation with predetermined probability via Chebyshev-based bounds. By combining an accurate linear approximation of the AC power flow equations with the distributionally robust chance constraint reformulation, the resulting optimization problem becomes convex and computationally tractable.
Distributions of methyl group rotational barriers in polycrystalline organic solids
Energy Technology Data Exchange (ETDEWEB)
Beckmann, Peter A., E-mail: pbeckman@brynmawr.edu, E-mail: wangxianlong@uestc.edu.cn [Department of Physics, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States); Conn, Kathleen G. [Department of Physics, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States); Division of Education and Human Services, Neumann University, One Neumann Drive, Aston, Pennsylvania 19014-1298 (United States); Mallory, Clelia W. [Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323 (United States); Department of Chemistry, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States); Mallory, Frank B. [Department of Chemistry, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States); Rheingold, Arnold L. [Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Dr., La Jolla, California 92093-0358 (United States); Rotkina, Lolita [Regional Nanotechnology Facility, Laboratory for Research on the Structure of Matter, University of Pennsylvania, 3231 Walnut Street, Philadelphia, Pennsylvania 19104-6202 (United States); Wang, Xianlong, E-mail: pbeckman@brynmawr.edu, E-mail: wangxianlong@uestc.edu.cn [Key Laboratory for NeuroInformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology, 4 North Jianshe Rd., 2nd Section, Chengdu 610054 (China)
2013-11-28
We bring together solid state {sup 1}H spin-lattice relaxation rate measurements, scanning electron microscopy, single crystal X-ray diffraction, and electronic structure calculations for two methyl substituted organic compounds to investigate methyl group (CH{sub 3}) rotational dynamics in the solid state. Methyl group rotational barrier heights are computed using electronic structure calculations, both in isolated molecules and in molecular clusters mimicking a perfect single crystal environment. The calculations are performed on suitable clusters built from the X-ray diffraction studies. These calculations allow for an estimate of the intramolecular and the intermolecular contributions to the barrier heights. The {sup 1}H relaxation measurements, on the other hand, are performed with polycrystalline samples which have been investigated with scanning electron microscopy. The {sup 1}H relaxation measurements are best fitted with a distribution of activation energies for methyl group rotation and we propose, based on the scanning electron microscopy images, that this distribution arises from molecules near crystallite surfaces or near other crystal imperfections (vacancies, dislocations, etc.). An activation energy characterizing this distribution is compared with a barrier height determined from the electronic structure calculations and a consistent model for methyl group rotation is developed. The compounds are 1,6-dimethylphenanthrene and 1,8-dimethylphenanthrene and the methyl group barriers being discussed and compared are in the 2–12 kJ mol{sup −1} range.
Power law distribution of dividends in horse races
Park, K.; Domany, E.
2001-02-01
We discovered that the distribution of dividends in Korean horse races follows a power law. A simple model of betting is proposed, which reproduces the observed distribution. The model provides a mechanism to arrive at the true underlying winning probabilities, which are initially unknown, in a self-organized collective fashion, through the dynamic process of betting. Numerical simulations yield excellent agreement with the empirical data.
Wind Power Forecasting Error Distributions: An International Comparison; Preprint
Energy Technology Data Exchange (ETDEWEB)
Hodge, B. M.; Lew, D.; Milligan, M.; Holttinen, H.; Sillanpaa, S.; Gomez-Lazaro, E.; Scharff, R.; Soder, L.; Larsen, X. G.; Giebel, G.; Flynn, D.; Dobschinski, J.
2012-09-01
Wind power forecasting is expected to be an important enabler for greater penetration of wind power into electricity systems. Because no wind forecasting system is perfect, a thorough understanding of the errors that do occur can be critical to system operation functions, such as the setting of operating reserve levels. This paper provides an international comparison of the distribution of wind power forecasting errors from operational systems, based on real forecast data. The paper concludes with an assessment of similarities and differences between the errors observed in different locations.
Evaluation of Current Controllers for Distributed Power Generation Systems
DEFF Research Database (Denmark)
Timbus, Adrian; Liserre, Marco; Teodorescu, Remus
2009-01-01
This paper discusses the evaluation of different current controllers employed for grid-connected distributed power generation systems having variable input power, such as wind turbines and photovoltaic systems. The focus is mainly set on linear controllers such as proportional....... First, in steady-state conditions, the contribution of controllers to the total harmonic distortion of the grid current is pursued. Further on, the behavior of controllers in the case of transient conditions like input power variations and grid voltage faults is also examined. Experimental results...
A Distributed Cooperative Power Allocation Method for Campus Buildings
Energy Technology Data Exchange (ETDEWEB)
Hao, He; Sun, Yannan; Carroll, Thomas E.; Somani, Abhishek
2015-09-01
We propose a coordination algorithm for cooperative power allocation among a collection of commercial buildings within a campus. We introduced thermal and power models of a typical commercial building Heating, Ventilation, and Air Conditioning (HVAC) system, and utilize model predictive control to characterize their power flexibility. The power allocation problem is formulated as a cooperative game using the Nash Bargaining Solution (NBS) concept, in which buildings collectively maximize the product of their utilities subject to their local flexibility constraints and a total power limit set by the campus coordinator. To solve the optimal allocation problem, a distributed protocol is designed using dual decomposition of the Nash bargaining problem. Numerical simulations are performed to demonstrate the efficacy of our proposed allocation method
Dynamic voltage regulation and power export in a distribution system using distributed generation
Institute of Scientific and Technical Information of China (English)
Aamir HANIF; Muhammad Ahmed CHOUDHRY
2009-01-01
The major aim of power quality (PQ) enhancing techniques is to maintain a specified voltage magnitude at a desired frequency for sensitive loads irrespective of faults on the power distribution network. The dynamic voltage restorer (DVR) is a device used to mitigate voltage sags to regulate load voltage. This paper presents a mathematical model for leading series voltage injection to mitigate sags thereby achieving the improvement of the utility power factor as well as power sharing between the DVR and utility. The power sharing will be as per requirement to compensate the sags considering the available distributed generation (DG). The approach of mitigating voltage sags using the concept of leading series voltage injection is suitable for those locations where phase shift in the voltage will not cause any problem. The MATLAB/SIMULINK SimPowerSystem toolbox has been used to obtain simulation results to verify the proposed mathematical model.
Ribeiro, A L B; de Carvalho, R R; La Barbera, F; Trevisan, M; Lopes, P A; Capelato, H V
2013-01-01
We introduce a new method to study the velocity distribution of galaxy systems, the Hellinger Distance (HD) - designed for detecting departures from a Gaussian velocity distribution. We define a relaxed galactic system as the one with unimodal velocity distribution and a normality deviation below a critical value (HD= 20) systems are significantly larger than in low multiplicity ones (N) and the gaussianity of the velocity distribution of the groups. Bright galaxies (M_r <=-20.7) residing in the inner and outer regions of groups, do not show significant differences in the listed quantities regardless if the group has a Gaussian (G) or a Non-Gaussian (NG) velocity distribution. However, the situation is significantly different when we examine the faint galaxies (-20.7
2013-01-08
... Employment and Training Administration Dana Holding Corporation; Power Technologies Group Division; Including... Technologies Group Division, Milwaukee, Wisconsin (subject firm). The worker group includes on-site leased... Company, Power Technologies Group Division, Milwaukee, Wisconsin, who were engaged in employment...
Directory of Open Access Journals (Sweden)
P.NIRMALA
2014-09-01
Full Text Available Modern power utilities have to respond to a number of challenges such as growth of electricity demand specially in non-linear loads in power grids, consequently, That higher power quality should be considered. In this paper, DPFC which is similar to unified power flow controller (UPFC in structure, which is used to mitigate the voltage sag and swell as a power quality issue. Unlike UPFC, the common dc-link in DPFC, between the shunt and series converter devices should be eliminated and three-phase series converter is divided to several single-phase series distributed converters through the power transmission line. And also to detect the voltage sags and find out the three single-phase reference voltages of DPFC, the synchronous reference frame method is proposed. Application of DPFC in power quality enhancement is simulated in Mat lab/Simulink environment which show the effectiveness of the proposed structure
Energy cost saving strategies in distributed power networks
Directory of Open Access Journals (Sweden)
Tcheukam Alain
2016-01-01
Full Text Available In this paper we study energy cost saving strategies in power networks in presence of prosumers. Three tips are considered: (i distributed power network architecture, (ii peak energy shaving with the integration of prosumers’ contribution, (iii Electric vehicles self-charging by means of prosumers’ production. The proposed distributed power network architecture reduces significantly the transmission costs and can reduce significantly the global energy cost up to 42 percent. Different types of prosumer who use self-charging photovoltaic systems, are able to intelligently buy energy from, or sell it, to the power grid. Therein, prosumers interact in a distributed environment during the purchase or sale of electric power using a double auction with negotiation mechanism. Using a two-step combined learning and optimization scheme, each prosumer can learn its optimal bidding strategy and forecast its energy production, consumption and storage. Our simulation results, conducted for the region of Sicily in Italy, show that the integration of prosumers can reduce peak hour costs up to 19 percent and 6 percent for eligible prosumers with electric vehicles.
Designing concept on lightning protection of overhead power distribution line
Energy Technology Data Exchange (ETDEWEB)
Yokoyama, Shigeru [Central Research Institute of Electric Power Industry, Kanagawa-ken (Japan)], E-mail: yokoyama@criepi.denken.or.jp
2007-07-01
The principle is shown for lightning protection of power distribution lines taking the effects of surge arresters, overhead ground wires and their combined use into consideration. Moreover an outline of a rational design method targeting direct lightning hits, induced over voltages and back flow currents from high structures. (author)
PHEMT Distributed Power Amplifier Adopting Broadband Impedance Transformer
DEFF Research Database (Denmark)
Narendra, K.; Limiti, E.; Paoloni, C.
2013-01-01
A non-uniform drain line distributed power amplifier (DPA) employing a broadband impedance transformer is presented. The DPA is based on GaAs PHEMT technology. The impedance transformer employs asymmetric coupled lines and transforms a low output impedance of the amplifier to a standard 50 Ω...
Synchronization Methods for Three Phase Distributed Power Generation Systems
DEFF Research Database (Denmark)
Timbus, Adrian Vasile; Teodorescu, Remus; Blaabjerg, Frede
2005-01-01
Nowadays, it is a general trend to increase the electricity production using Distributed Power Generation Systems (DPGS) based on renewable energy resources such as wind, sun or hydrogen. If these systems are not properly controlled, their connection to the utility network can generate problems o...
Seasonal wave power distribution around the Indian coast
Digital Repository Service at National Institute of Oceanography (India)
Chandramohan, P.; Nayak, B.U.
The ship reported wave data published in Indian Daily Weather Report were compiled for the period of 16 years from 1968 to 1983 for 5 degrees x 5 degrees grids around the Indian coast. The distribution of wave power potential during the three...
High Resolution PV Power Modeling for Distribution Circuit Analysis
Energy Technology Data Exchange (ETDEWEB)
Norris, B. L.; Dise, J. H.
2013-09-01
NREL has contracted with Clean Power Research to provide 1-minute simulation datasets of PV systems located at three high penetration distribution feeders in the service territory of Southern California Edison (SCE): Porterville, Palmdale, and Fontana, California. The resulting PV simulations will be used to separately model the electrical circuits to determine the impacts of PV on circuit operations.
Using Model Checking for Analyzing Distributed Power Control Problems
DEFF Research Database (Denmark)
Brihaye, Thomas; Jungers, Marc; Lasaulce, Samson
2010-01-01
Model checking (MC) is a formal verification technique which has been known and still knows a resounding success in the computer science community. Realizing that the distributed power control ( PC) problem can be modeled by a timed game between a given transmitter and its environment, the authors...
Electron beam machining using rotating and shaped beam power distribution
Elmer, John W.; O'Brien, Dennis W.
1996-01-01
An apparatus and method for electron beam (EB) machining (drilling, cutting and welding) that uses conventional EB guns, power supplies, and welding machine technology without the need for fast bias pulsing technology. The invention involves a magnetic lensing (EB optics) system and electronic controls to: 1) concurrently bend, focus, shape, scan, and rotate the beam to protect the EB gun and to create a desired effective power-density distribution, and 2) rotate or scan this shaped beam in a controlled way. The shaped beam power-density distribution can be measured using a tomographic imaging system. For example, the EB apparatus of this invention has the ability to drill holes in metal having a diameter up to 1000 .mu.m (1 mm or larger), compared to the 250 .mu.m diameter of laser drilling.
Exploring empowerment in settings: mapping distributions of network power.
Neal, Jennifer Watling
2014-06-01
This paper brings together two trends in the empowerment literature-understanding empowerment in settings and understanding empowerment as relational-by examining what makes settings empowering from a social network perspective. Specifically, extending Neal and Neal's (Am J Community Psychol 48(3/4):157-167, 2011) conception of network power, an empowering setting is defined as one in which (1) actors have existing relationships that allow for the exchange of resources and (2) the distribution of network power among actors in the setting is roughly equal. The paper includes a description of how researchers can examine distributions of network power in settings. Next, this process is illustrated in both an abstract example and using empirical data on early adolescents' peer relationships in urban classrooms. Finally, implications for theory, methods, and intervention related to understanding empowering settings are explored.
Interacting discrete Markov processes with power-law probability distributions
Ridley, Kevin D.; Jakeman, Eric
2017-09-01
During recent years there has been growing interest in the occurrence of long-tailed distributions, also known as heavy-tailed or fat-tailed distributions, which can exhibit power-law behaviour and often characterise physical systems that undergo very large fluctuations. In this paper we show that the interaction between two discrete Markov processes naturally generates a time-series characterised by such a distribution. This possibility is first demonstrated by numerical simulation and then confirmed by a mathematical analysis that enables the parameter range over which the power-law occurs to be quantified. The results are supported by comparison of numerical results with theoretical predictions and general conclusions are drawn regarding mechanisms that can cause this behaviour.
Distribution of Acoustic Power Spectra for an Isolated Helicopter Fuselage
Directory of Open Access Journals (Sweden)
Kusyumov A.N.
2016-01-01
Full Text Available The broadband aerodynamic noise can be studied, assuming isotropic flow, turbulence and decay. Proudman’s approach allows practical calculations of noise based on CFD solutions of RANS or URANS equations at the stage of post processing and analysis of the solution. Another aspect is the broadband acoustic spectrum and the distribution of acoustic power over a range of frequencies. The acoustic energy spectrum distribution in isotropic turbulence is non monotonic and has a maximum at a certain value of Strouhal number. In the present work the value of acoustic power peak frequency is determined using a prescribed form of acoustic energy spectrum distribution presented in papers by S. Sarkar and M. Y. Hussaini and by G. M. Lilley. CFD modelling of the flow around isolated helicopter fuselage model was considered using the HMB CFD code and the RANS equations.
Parallel and distributed processing in power system simulation and control
Energy Technology Data Exchange (ETDEWEB)
Falcao, Djalma M. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia
1994-12-31
Recent advances in computer technology will certainly have a great impact in the methodologies used in power system expansion and operational planning as well as in real-time control. Parallel and distributed processing are among the new technologies that present great potential for application in these areas. Parallel computers use multiple functional or processing units to speed up computation while distributed processing computer systems are collection of computers joined together by high speed communication networks having many objectives and advantages. The paper presents some ideas for the use of parallel and distributed processing in power system simulation and control. It also comments on some of the current research work in these topics and presents a summary of the work presently being developed at COPPE. (author) 53 refs., 2 figs.
Efficient Estimation of Smooth Distributions From Coarsely Grouped Data
DEFF Research Database (Denmark)
Rizzi, Silvia; Gampe, Jutta; Eilers, Paul H C
2015-01-01
in the tail area. Age group-specific disease incidence rates and abridged life tables are examples of binned data. We propose a versatile method for ungrouping histograms that assumes that only the underlying distribution is smooth. Because of this modest assumption, the approach is suitable for most...... applications. The method is based on the composite link model, with a penalty added to ensure the smoothness of the target distribution. Estimates are obtained by maximizing a penalized likelihood. This maximization is performed efficiently by a version of the iteratively reweighted least-squares algorithm......Ungrouping binned data can be desirable for many reasons: Bins can be too coarse to allow for accurate analysis; comparisons can be hindered when different grouping approaches are used in different histograms; and the last interval is often wide and open-ended and, thus, covers a lot of information...
2012-11-26
... COMMISSION Preoperational Testing of Onsite Electric Power Systems To Verify Proper Load Group Assignments... Power Systems to Verify Proper Load Group Assignments, Electrical Separation, and Redundancy.'' DG-1294... encompass preoperational testing of electrical power systems used to meet current Station...
ASYMPTOTIC PROPERTIES OF MLE FOR WEIBULL DISTRIBUTION WITH GROUPED DATA
Institute of Scientific and Technical Information of China (English)
XUEHongqi; SONGLixin
2002-01-01
A grouped data model for weibull distribution is considered.Under mild conditions .the maximum likelihood estimators(MLE)are shown to be identifiable,strongly consistent,asymptotically normal,and satisfy the law of iterated logarithm .Newton iteration algorthm is also condsidered,which converges to the unique solution of the likelihood equation.Moreover,we extend these results to a random case.
Improving Advanced Inverter Control Convergence in Distribution Power Flow
Energy Technology Data Exchange (ETDEWEB)
Nagarajan, Adarsh; Palmintier, Bryan; Ding, Fei; Mather, Barry; Baggu, Murali
2016-11-21
Simulation of modern distribution system powerflow increasingly requires capturing the impact of advanced PV inverter voltage regulation on powerflow. With Volt/var control, the inverter adjusts its reactive power flow as a function of the point of common coupling (PCC) voltage. Similarly, Volt/watt control curtails active power production as a function of PCC voltage. However, with larger systems and higher penetrations of PV, this active/reactive power flow itself can cause significant changes to the PCC voltage potentially introducing oscillations that slow the convergence of system simulations. Improper treatment of these advanced inverter functions could potentially lead to incorrect results. This paper explores a simple approach to speed such convergence by blending in the previous iteration's reactive power estimate to dampen these oscillations. Results with a single large (5MW) PV system and with multiple 500kW advanced inverters show dramatic improvements using this approach.
Chattanooga Electric Power Board Case Study Distribution Automation
Energy Technology Data Exchange (ETDEWEB)
Glass, Jim [Chattanooga Electric Power Board (EPB), TN (United States); Melin, Alexander M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Starke, Michael R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2016-10-01
In 2009, the U.S. Department of Energy under the American Recovery and Reinvestment Act (ARRA) awarded a grant to the Chattanooga, Tennessee, Electric Power Board (EPB) as part of the Smart Grid Investment Grant Program. The grant had the objective “to accelerate the transformation of the nation’s electric grid by deploying smart grid technologies.” This funding award enabled EPB to expedite the original smart grid implementation schedule from an estimated 10-12 years to 2.5 years. With this funding, EPB invested heavily in distribution automation technologies including installing over 1,200 automated circuit switches and sensors on 171 circuits. For utilities considering a commitment to distribution automation, there are underlying questions such as the following: “What is the value?” and “What are the costs?” This case study attempts to answer these questions. The primary benefit of distribution automation is increased reliability or reduced power outage duration and frequency. Power outages directly impact customer economics by interfering with business functions. In the past, this economic driver has been difficult to effectively evaluate. However, as this case study demonstrates, tools and analysis techniques are now available. In this case study, the impact on customer costs associated with power outages before and after the implementation of distribution automation are compared. Two example evaluations are performed to demonstrate the benefits: 1) a savings baseline for customers under normal operations1 and 2) customer savings for a single severe weather event. Cost calculations for customer power outages are performed using the US Department of Energy (DOE) Interruption Cost Estimate (ICE) calculator2. This tool uses standard metrics associated with outages and the customers to calculate cost impact. The analysis shows that EPB customers have seen significant reliability improvements from the implementation of distribution automation. Under
Characterizations of the power distribution by record values
Indian Academy of Sciences (India)
Min-Young Lee
2016-05-01
Let $\\{ X_n, n \\geq 1\\}$ be a sequence of i.i.d. random variables which has absolutely continuous distribution function $F(x)$ with probability density function $f(x)$ and $F(0) = 0$. Assume that $X_n$ belongs to the class $C^\\ast_1$ or $C_2$. Then $X_k$ has the power distribution if and only if $X_k$ and $\\frac{X_{L(n+1)}}{X_{L(n)}}$ or $\\frac{X_{L(n+1)}}{X_{L(n)}}$ and $\\frac{X_{L(n)}}{X_{L(n--1)}}$ are identically distributed, respectively. Suppose that $X_n$ belongs to the class $C_3$. Also, $X_k$ has the power distribution if and only if $X_{L(n+1)}$ and $X_{L(n)}\\cdot V$ are identically distributed, where $V$ is independent of $X_{L(n)}$ and $X_{L(n+1)}$ and is distributed as $X_n$’s.
Energy Technology Data Exchange (ETDEWEB)
Davis, M. W.; Broadwater, R.; Hambrick, J.
2007-07-01
This report summarizes the development of models for distributed generation and distribution circuit voltage regulation equipment for unbalanced power systems and their verification through actual field measurements.
Distributed renewable power from biomass and other waste fuels
Lyons, Chris
2012-03-01
The world population is continually growing and putting a burden on our fossil fuels. These fossil fuels such as coal, oil and natural gas are used for a variety of critical needs such as power production and transportation. While significant environmental improvements have been made, the uses of these fuels are still causing significant ecological impacts. Coal power production efficiency has not improved over the past thirty years and with relatively cheap petroleum cost, transportation mileage has not improved significantly either. With the demand for these fossil fuels increasing, ultimately price will also have to increase. This presentation will evaluate alternative power production methods using localized distributed generation from biomass, municipal solid waste and other waste sources of organic materials. The presentation will review various gasification processes that produce a synthetic gas that can be utilized as a fuel source in combustion turbines for clean and efficient combined heat and power. This fuel source can produce base load renewable power. In addition tail gases from the production of bio-diesel and methanol fuels can be used to produce renewable power. Being localized can reduce the need for long and costly transmission lines making the production of fuels and power from waste a viable alternative energy source for the future.
Reconstructing the galaxy redshift distribution from angular cross power spectra
Sun, L; Tao, C
2015-01-01
The control of photometric redshift (photo-$z$) errors is a crucial and challenging task for precision weak lensing cosmology. The spacial cross-correlations (equivalently, the angular cross power spectra) of galaxies between tomographic photo-$z$ bins are sensitive to the true redshift distribution $n_i(z)$ of each bin and hence can help calibrate the photo-$z$ error distribution for weak lensing surveys. Using Fisher matrix analysis, we investigate the contributions of various components of the angular power spectra to the constraints of $n_i(z)$ parameters and demonstrate the importance of the cross power spectra therein, especially when catastrophic photo-$z$ errors are present. We further study the feasibility of reconstructing $n_i(z)$ from galaxy angular power spectra using Markov Chain Monte Carlo estimation. Considering an LSST-like survey with $10$ photo-$z$ bins, we find that the underlying redshift distribution can be determined with a fractional precision ($\\sigma(\\theta)/\\theta$ for parameter $\\...
Convex relaxation of Optimal Power Flow in Distribution Feeders with embedded solar power
DEFF Research Database (Denmark)
Hermann, Alexander Niels August; Wu, Qiuwei; Huang, Shaojun;
2016-01-01
There is an increasing interest in using Distributed Energy Resources (DER) directly coupled to end user distribution feeders. This poses an array of challenges because most of today’s distribution feeders are designed for unidirectional power flow. Therefore when installing DERs such as solar pa...... to minimize the global line losses of the feeder. The mathematical model is presented in details. Further, case studies are completed with simulations involving a 15-bus radial distribution system. These simulations are run for 24 hour periods, with actual solar data and demand data....
A New Lifetime Distribution and Its Power Transformation
Directory of Open Access Journals (Sweden)
Ammar M. Sarhan
2014-01-01
Full Text Available New one-parameter and two-parameter distributions are introduced in this paper. The failure rate of the one-parameter distribution is unimodal (upside-down bathtub, while the failure rate of the two-parameter distribution can be decreasing, increasing, unimodal, increasing-decreasing-increasing, or decreasing-increasing-decreasing, depending on the values of its two parameters. The two-parameter distribution is derived from the one-parameter distribution by using a power transformation. We discuss some properties of these two distributions, such as the behavior of the failure rate function, the probability density function, the moments, skewness, and kurtosis, and limiting distributions of order statistics. Maximum likelihood estimation for the two-parameter model using complete samples is investigated. Different algorithms for generating random samples from the two new models are given. Applications to real data are discussed and compared with the fit attained by some one- and two-parameter distributions. Finally, a simulation study is carried out to investigate the mean square error of the maximum likelihood estimators, the coverage probability, and the width of the confidence intervals of the unknown parameters.
Estimating trend precision and power to detect trends across grouped count data
Gray, B.R.; Burlew, M.M.
2007-01-01
Ecologists commonly use grouped or clustered count data to estimate temporal trends in counts, abundance indices, or abundance. For example, the U.S. Breeding Bird Survey data represent multiple counts of birds from within each of multiple, spatially defined routes. Despite a reliance on grouped counts, analytical methods for prospectively estimating precision of trend estimates or statistical power to detect trends that explicitly acknowledge the characteristics of grouped count data are undescribed. These characteristics include the fact that the sampling variance is an increasing function of the mean, and that sampling and group-level variance estimates are generally estimated on different scales (the sampling and log scales, respectively). We address these issues for repeated sampling of a single population using an analytical approach that has the flavor of a generalized linear mixed model, specifically that of a negative binomial-distributed count variable with random group effects. The count mean, including grand intercept, trend, and random group effects, is modeled linearly on the log scale, while sampling variance of the mean is estimated on the log scale via the delta method. Results compared favorably with those derived using Monte Carlo simulations. For example, at trend = 5% per temporal unit, differences in standard errors and in power were modest relative to those estimated by simulation (???|11|% and ???|16|%, respectively), with relative differences among power estimates decreasing to ???|7|% when power estimated by simulations was ???0.50. Similar findings were obtained using data from nine surveys of fingernail clams in the Mississippi River. The proposed method is suggested (1) where simulations are not practical and relative precision or power is desired, or (2) when multiple precision or power calculations are required and where the accuracy of a fraction of those calculations will be confirmed using simulations. ?? 2007 by the Ecological
Multi-Objective Reactive Power Optimization of Distribution Network with Distributed Generation
Directory of Open Access Journals (Sweden)
Zhao Hui
2016-01-01
Full Text Available Distributed generation (DG is considered to be a very promising alternative of power generation because of its tremendous environmental, social, and economic benefits. But the randomness and intermittent of DGs brings new problems to the system. This paper analyzes the reactive power optimization problem of distribution network with correlative DGs based on scenario analysis method. A new scenario division rule according to the joint distribution function of wind-PV power outputs is proposed in the paper. Then a multi-objective reactive power optimization model whose objects include the minimum active power losses, the minimum voltage deviation and the maximum static voltage stability margin is established. Non-dominated sorting genetic algorithm-II is used to solve the model. At the last of the paper, the model and the algorithm proposed are verified with an improved IEEE 33-bus system. The results show that the model will be a reference to the reactive power optimization problem in distribution system.
Distributed Generation in Power Systems: An Overview and Key Issues
DEFF Research Database (Denmark)
Singh, Sri Niwas
2009-01-01
The necessity for smart electrical systems having minimum technical loss and environmental impact is providing impetus to go for Distributed Generations (DGs) which may offer several other advantages such as reduced transmission and distribution system resources, increased reliability, better power...... quality, etc. However, depending on the system configuration and management, these advantages may not be true. Moreover, due to structural and managerial changes in the electricity supply industry motivated with introduction of completion, the role of small generations distributed in the low....../medium voltage network has gained importance. This paper adopts a systematic approach by focusing on the most important research areas related to the distributed generations. Various DG technologies are described and penetration of DGs in the Indian system has been discussed. This paper also highlights the key...
Deviation from power law of the global seismic moment distribution
Serra, Isabel; Corral, Álvaro
2017-01-01
The distribution of seismic moment is of capital interest to evaluate earthquake hazard, in particular regarding the most extreme events. We make use of likelihood-ratio tests to compare the simple Gutenberg-Richter power-law (PL) distribution with two statistical models that incorporate an exponential tail, the so-called tapered Gutenberg-Richter (Tap) and the truncated gamma, when fitted to the global CMT earthquake catalog. Although the Tap distribution does not introduce any significant improvement of fit respect the PL, the truncated gamma does. Simulated samples of this distribution, with parameters β = 0.68 and mc = 9.15 and reshuffled in order to mimic the time occurrence of the order statistics of the empirical data, are able to explain the temporal heterogeneity of global seismicity both before and after the great Sumatra-Andaman earthquake of 2004. PMID:28053311
Energy storage system control strategies for power distribution systems
Directory of Open Access Journals (Sweden)
Areewan Kajorndech
2015-03-01
Full Text Available Energy storage systems have been widely employed to attain several benefits, such as reliability improvement, stabilization of power systems connected with renewable energy resources, economic benefits and etc. To achieve the above objectives, the appropriate and effective control strategies for energy storage systems are needed to be developed. This research proposes energy storage system control strategies for power distribution systems equipped with a limited size of energy storage system in order to improve reliability and save energy costs by determining an optimal charging schedule of the energy storage system. Simulation results demonstrate the benefits of energy storage system applications under the different control strategies.
Intelligent Fault Diagnosis in a Power Distribution Network
Directory of Open Access Journals (Sweden)
Oluleke O. Babayomi
2016-01-01
Full Text Available This paper presents a novel method of fault diagnosis by the use of fuzzy logic and neural network-based techniques for electric power fault detection, classification, and location in a power distribution network. A real network was used as a case study. The ten different types of line faults including single line-to-ground, line-to-line, double line-to-ground, and three-phase faults were investigated. The designed system has 89% accuracy for fault type identification. It also has 93% accuracy for fault location. The results indicate that the proposed technique is effective in detecting, classifying, and locating low impedance faults.
Distributed Optimal Power Flow of AC/DC Interconnected Power Grid Using Synchronous ADMM
Liang, Zijun; Lin, Shunjiang; Liu, Mingbo
2017-05-01
Distributed optimal power flow (OPF) is of great importance and challenge to AC/DC interconnected power grid with different dispatching centres, considering the security and privacy of information transmission. In this paper, a fully distributed algorithm for OPF problem of AC/DC interconnected power grid called synchronous ADMM is proposed, and it requires no form of central controller. The algorithm is based on the fundamental alternating direction multiplier method (ADMM), by using the average value of boundary variables of adjacent regions obtained from current iteration as the reference values of both regions for next iteration, which realizes the parallel computation among different regions. The algorithm is tested with the IEEE 11-bus AC/DC interconnected power grid, and by comparing the results with centralized algorithm, we find it nearly no differences, and its correctness and effectiveness can be validated.
Power system distributed oscilation detection based on Synchrophasor data
Ning, Jiawei
Along with increasing demand for electricity, integration of renewable energy and deregulation of power market, power industry is facing unprecedented challenges nowadays. Within the last couple of decades, several serious blackouts have been taking place in United States. As an effective approach to prevent that, power system small signal stability monitoring has been drawing more interests and attentions from researchers. With wide-spread implementation of Synchrophasors around the world in the last decade, power systems real-time online monitoring becomes much more feasible. Comparing with planning study analysis, real-time online monitoring would benefit control room operators immediately and directly. Among all online monitoring methods, Oscillation Modal Analysis (OMA), a modal identification method based on routine measurement data where the input is unmeasured ambient excitation, is a great tool to evaluate and monitor power system small signal stability. Indeed, high sampling Synchrophasor data around power system is fitted perfectly as inputs to OMA. Existing methods in OMA for power systems are all based on centralized algorithms applying at control centers only; however, with rapid growing number of online Synchrophasors the computation burden at control centers is and will be continually exponentially expanded. The increasing computation time at control center compromises the real-time feature of online monitoring. The communication efforts between substation and control center will also be out of reach. Meanwhile, it is difficult or even impossible for centralized algorithms to detect some poorly damped local modes. In order to avert previous shortcomings of centralized OMA methods and embrace the new changes in the power systems, two new distributed oscillation detection methods with two new decentralized structures are presented in this dissertation. Since the new schemes brought substations into the big oscillation detection picture, the proposed
Distribution of Faint Atomic Gas in Hickson Compact Groups
Borthakur, Sanchayeeta; Verdes-Montenegro, Lourdes; Heckman, Timothy M; Zhu, Guangtun; Braatz, James A
2015-01-01
We present 21cm HI observations of four Hickson Compact Groups with evidence for a substantial intragroup medium using the Robert C. Byrd Green Bank Telescope (GBT). By mapping H I emission in a region of 25$^{\\prime}\\times$25$^{\\prime}$ (140-650 kpc) surrounding each HCG, these observations provide better estimates of HI masses. In particular, we detected 65% more \\HI than that detected in the Karl G. Jansky Very Large Array (VLA) imaging of HCG92. We also identify if the diffuse gas has the same spatial distribution as the high-surface brightness (HSB) HI features detected in the VLA maps of these groups by comparing the HI strengths between the observed and modeled masses based on VLA maps. We found that the HI observed with the GBT to have a similar spatial distribution as the HSB structures in HCGs 31 and 68. Conversely, the observed HI distributions in HCGs44 and 92 were extended and showed significant offsets from the modeled masses. Most of the faint gas in HCG44 lies to the Northeast-Southwest region...
Directory of Open Access Journals (Sweden)
PARWAL Arvind
2013-05-01
Full Text Available The loads in rustic area are preeminent pump sets used for various applications i.e. lift irrigation system. Minimal power factor and minimal load factor is found in loads. Further, being a factordissemination of loads, load density is found low. The present distribution system dwell of three-phase 11KV/433Volts distribution transformer with extended L.T Lines. In this system, voltage profile and reliability are poor. In this paper, HVDS is unveiled with smallcapacity distribution transformers. A simple load flow technique is used for solving distribution networks before and after implementation of HVDS. The advantages of implementing HVDS against LVDS system are discussed.
Directory of Open Access Journals (Sweden)
Rachid DEHINI
2010-12-01
Full Text Available In this paper, the main aim is to confront the performance of shunt active power filter (SAPF and the shunt hybrid active power filter (SHAPF to achieve flexibility and reliability of the filter devices. Both of the two devices used the classical proportional-integral controller for pulse generation to trigger the inventers MOSFETs. In the adopted hybrid active filter there is a passive power filter with high power rating to filter the low order harmonies and one active filter with low power rating to filter the other high order harmonies. In order to investigate the effectiveness of (SHAPF, the studies have been accomplished using simulation with the MATLAB-SIMULINK. The results show That (SHAPF is more effective than (SAPF, and has lower cost.
Power exponential velocity distributions in disordered porous media
Matyka, Maciej; Koza, Zbigniew
2016-01-01
Velocity distribution functions link the micro- and macro-level theories of fluid flow through porous media. Here we study them for the fluid absolute velocity and its longitudinal and lateral components relative to the macroscopic flow direction in a model of a random porous medium. We claim that all distributions follow the power exponential law controlled by an exponent $\\gamma$ and a shift parameter $u_0$ and examine how these parameters depend on the porosity. We find that $\\gamma$ has a universal value $1/2$ at the percolation threshold and grows with the porosity, but never exceeds 2.
Distributed Generation Using Indirect Matrix Converter in Reverse Power Mode
DEFF Research Database (Denmark)
Liu, Xiong; Chiang Loh, Poh; Wang, Peng
2013-01-01
not appropriate. Like most power converters, the operation of the IMC can surely be reversed to produce a boosted gain, but so far its relevant control principles have not been discussed. These challenges are now addressed in this paper with distributed generation suggested as a potential application. Simulation......Indirect matrix converter (IMC) is an alternative for ac/ac energy conversion, usually operated with a voltage stepped-down gain of only 0.866. For applications like distribution generation where voltage-boost functionality is required, the traditional style of operating the IMC is therefore...
Integration of distributed generation in the power system
Bollen, Math H J
2011-01-01
"The integration of new sources of energy like wind power, solar-power, small-scale generation, or combined heat and power in the power grid is something that impacts a lot of stakeholders: network companies (both distribution and transmission), the owners and operators of the DG units, other end-users of the power grid (including normal consumers like you and me) and not in the least policy makers and regulators. There is a lot of misunderstanding about the impact of DG on the power grid, with one side (including mainly some but certainly not all, network companies) claiming that the lights will go out soon, whereas the other side (including some DG operators and large parks of the general public) claiming that there is nothing to worry about and that it's all a conspiracy of the large production companies that want to protect their own interests and keep the electricity price high. The authors are of the strong opinion that this is NOT the way one should approach such an important subject as the integration...
Using Model Checking for Analyzing Distributed Power Control Problems
Directory of Open Access Journals (Sweden)
Thomas Brihaye
2010-01-01
Full Text Available Model checking (MC is a formal verification technique which has been known and still knows a resounding success in the computer science community. Realizing that the distributed power control (PC problem can be modeled by a timed game between a given transmitter and its environment, the authors wanted to know whether this approach can be applied to distributed PC. It turns out that it can be applied successfully and allows one to analyze realistic scenarios including the case of discrete transmit powers and games with incomplete information. The proposed methodology is as follows. We state some objectives a transmitter-receiver pair would like to reach. The network is modeled by a game where transmitters are considered as timed automata interacting with each other. The objectives are then translated into timed alternating-time temporal logic formulae and MC is exploited to know whether the desired properties are verified and determine a winning strategy.
Optimal Power Flow for Distribution Systems under Uncertain Forecasts: Preprint
Energy Technology Data Exchange (ETDEWEB)
Dall' Anese, Emiliano; Baker, Kyri; Summers, Tyler
2016-12-01
The paper focuses on distribution systems featuring renewable energy sources and energy storage devices, and develops an optimal power flow (OPF) approach to optimize the system operation in spite of forecasting errors. The proposed method builds on a chance-constrained multi-period AC OPF formulation, where probabilistic constraints are utilized to enforce voltage regulation with a prescribed probability. To enable a computationally affordable solution approach, a convex reformulation of the OPF task is obtained by resorting to i) pertinent linear approximations of the power flow equations, and ii) convex approximations of the chance constraints. Particularly, the approximate chance constraints provide conservative bounds that hold for arbitrary distributions of the forecasting errors. An adaptive optimization strategy is then obtained by embedding the proposed OPF task into a model predictive control framework.
Robust Distributed Power Control in Cognitive Radio Networks
fard, Saeideh Parsaei
2011-01-01
We propose a robust distributed uplink power allocation algorithm for underlay cognitive radio networks (CRNs) with a view to maximizing the total utility of secondary users (SUs) when channel gains from SUs to primary base stations, and interference caused by primary users (PUs) to the SUs' base station are uncertain. In doing so, we utilize the worst-case robust optimization to keep the interference caused by SUs to each primary base station below a given threshold, and satisfy the SUs' quality of service for all realizations of uncertainty. We model each uncertain parameter by a bounded distance between its estimated and exact values, and formulate the robust power allocation problem via protection values for constraints. We demonstrate that the convexity of our problem is preserved, and in some cases converts into a geometric programming problem, which we solve via a distributed algorithm by using Lagrange dual decomposition. To reduce the cost of robustness, defined as the reduction in the total utility ...
Automatic Regionalization Algorithm for Distributed State Estimation in Power Systems
Energy Technology Data Exchange (ETDEWEB)
Wang, Dexin; Yang, Liuqing; Florita, Anthony; Alam, S.M. Shafiul; Elgindy, Tarek; Hodge, Bri-Mathias
2017-04-24
The deregulation of the power system and the incorporation of generation from renewable energy sources recessitates faster state estimation in the smart grid. Distributed state estimation (DSE) has become a promising and scalable solution to this urgent demand. In this paper, we investigate the regionalization algorithms for the power system, a necessary step before distributed state estimation can be performed. To the best of the authors' knowledge, this is the first investigation on automatic regionalization (AR). We propose three spectral clustering based AR algorithms. Simulations show that our proposed algorithms outperform the two investigated manual regionalization cases. With the help of AR algorithms, we also show how the number of regions impacts the accuracy and convergence speed of the DSE and conclude that the number of regions needs to be chosen carefully to improve the convergence speed of DSEs.
Control strategies for power distribution networks with electric vehicles integration
DEFF Research Database (Denmark)
Hu, Junjie
Demand side resources, like electric vehicles (EVs), can become integral parts of a smart grids because instead of just consuming power they are capable of providing valuable services to power systems. EVs can be used to balance the intermittent renewable energy resources such as wind and solar...... on designing control strategies for congestion control in distribution network with multiple actors, such as the distribution system operator (DSO), eet operators (FO), and electric vehicle owners (or prosumers), considering their self-interests and operational constraints. Note that the control problem...... scheme of EVs according to the users' energy driving requirements and the forecasted day-ahead electricity market price. Several electric vehicle eet operators are specied to manage the electric vehicle eets. The method of market based control can then be used by the DSO to interact with the electric...
Optimal Power Flow for Distribution Systems under Uncertain Forecasts
Energy Technology Data Exchange (ETDEWEB)
Dall' Anese, Emiliano; Baker, Kyri; Summers, Tyler
2016-12-29
The paper focuses on distribution systems featuring renewable energy sources and energy storage devices, and develops an optimal power flow (OPF) approach to optimize the system operation in spite of forecasting errors. The proposed method builds on a chance-constrained multi-period AC OPF formulation, where probabilistic constraints are utilized to enforce voltage regulation with a prescribed probability. To enable a computationally affordable solution approach, a convex reformulation of the OPF task is obtained by resorting to i) pertinent linear approximations of the power flow equations, and ii) convex approximations of the chance constraints. Particularly, the approximate chance constraints provide conservative bounds that hold for arbitrary distributions of the forecasting errors. An adaptive optimization strategy is then obtained by embedding the proposed OPF task into a model predictive control framework.
Water group ion distributions in the midcometosheath of comet Halley
Huddleston, D. E.; Neugebauer, M.; Goldstein, Bruce E.
1993-01-01
In the midcometosheath of comet Halley (1 x 10(exp 5) to 2 x 10(exp 5) km from the nucleus) the center-of-mass plasma frame is approximately the bulk flow velocity of the cometary ions, and the Alfven wave speed is an appreciable fraction of the flow speed. Here, the peaks of the water group ion distributions observed by the Giotto ion mass spectrometer are at velocities consistently below the expected pickup speed. It is shown that this effect is consistent with the scattering of the new pickup ions onto a bispherical shell distribution. The model does not fit the data inside approximately 1.2 x 10(exp 5) km, however, possibly as a result of the growing importance of collisions or the presence of other processes such as scattering on obliquely propagating magnetosonic waves.
The Power Structure of 2-Generator 2-Groups of Class Two
Institute of Scientific and Technical Information of China (English)
Friedrich L. Kluempen
2002-01-01
In 1934, Hall introduced regular p-groups. Any regular 2-group is abelian. A regular p-group is power closed, exponent closed, strongly semi-pabelian, and an exact power margin group. The study of these properties and relationships among them constitutes the investigation of the power structure of a p-group. In this paper, we classify 2-generator 2-groups of nilpotency class two according to their power structure.
London house prices are power-law distributed
MacKay, Niall
2010-01-01
In this pilot study we explore the house price distributions for London, Manchester, Bristol, Newcastle, Birmingham and Leeds. We find Pareto (power law) behaviour in their upper tails, which is clearly distinct from lognormal behaviour in the cases of London and Manchester. We propose an index of Housing Wealth Inequality based on the Pareto exponent and analogous to the Gini coefficient, and comment on its possible uses.
Electric Power Quality and Distributed Generation in Cuba
Directory of Open Access Journals (Sweden)
Miguel Castro Fernández
2010-10-01
Full Text Available Diesel engine generator (RM is one of the most used technologies on distributed generation (DG. The presence of RM, no manner its operation form need an analysis about differents problems: one of them is related with power quality (PQ. First results obained inside one study directed to obtain answers about differents perturbations for the RM presence like shortcircuit and voltage variation on RM termianls and rejected charge are presented in this paper.
Optimal Node Grouping for Water Distribution System Demand Estimation
Directory of Open Access Journals (Sweden)
Donghwi Jung
2016-04-01
Full Text Available Real-time state estimation is defined as the process of calculating the state variable of interest in real time not being directly measured. In a water distribution system (WDS, nodal demands are often considered as the state variable (i.e., unknown variable and can be estimated using nodal pressures and pipe flow rates measured at sensors installed throughout the system. Nodes are often grouped for aggregation to decrease the number of unknowns (demands in the WDS demand estimation problem. This study proposes an optimal node grouping model to maximize the real-time WDS demand estimation accuracy. This Kalman filter-based demand estimation method is linked with a genetic algorithm for node group optimization. The modified Austin network demand is estimated to demonstrate the proposed model. True demands and field measurements are synthetically generated using a hydraulic model of the study network. Accordingly, the optimal node groups identified by the proposed model reduce the total root-mean-square error of the estimated node group demand by 24% compared to that determined by engineering knowledge. Based on the results, more pipe flow sensors should be installed to measure small flows and to further enhance the demand estimation accuracy.
Technique applied in electrical power distribution for Satellite Launch Vehicle
Directory of Open Access Journals (Sweden)
João Maurício Rosário
2010-09-01
Full Text Available The Satellite Launch Vehicle electrical network, which is currently being developed in Brazil, is sub-divided for analysis in the following parts: Service Electrical Network, Controlling Electrical Network, Safety Electrical Network and Telemetry Electrical Network. During the pre-launching and launching phases, these electrical networks are associated electrically and mechanically to the structure of the vehicle. In order to succeed in the integration of these electrical networks it is necessary to employ techniques of electrical power distribution, which are proper to Launch Vehicle systems. This work presents the most important techniques to be considered in the characterization of the electrical power supply applied to Launch Vehicle systems. Such techniques are primarily designed to allow the electrical networks, when submitted to the single-phase fault to ground, to be able of keeping the power supply to the loads.
Distributed Solar Photovoltaic Power Production - Technology and Benefits
Energy Technology Data Exchange (ETDEWEB)
Matos, Al [PSE& G; Stuby, Rick [Petra Solar
2011-11-02
As part of its nationally recognized Solar 4 All program, PSE&G has partnered with Petra Solar to deploy the world’s first and largest pole attached solar project. The project, based on Petra Solar’s distributed Smart Solar solution, will create a 40 megawatt solar “virtual power plant.” In deployment as 200,000 individual grid-connected solar power producers on utility poles in PSE&G territory, Petra Solar SunWave® solutions leverage Smart Grid communications and high-tech panel-level inverters to implement a robust system with many technical benefits over traditional solar photovoltaic solutions. The program overview, deployment model, smart grid communications and enabling inverter technology and safety features will be presented, as well the future challenges of, and solutions for, solar power intermittency as photovoltaic penetration on the electric grid increases.
Assessment of distributed solar power systems: Issues and impacts
Moyle, R. A.; Chernoff, H.; Schweizer, T. C.; Patton, J. B.
1982-11-01
The installation of distributed solar-power systems presents electric utilities with a host of questions. Some of the technical and economic impacts of these systems are discussed. Among the technical interconnect issues are isolated operation, power quality, line safety, and metering options. Economic issues include user purchase criteria, structures and installation costs, marketing and product distribution costs, and interconnect costs. An interactive computer program that allows easy calculation of allowable system prices and allowable generation-equipment prices was developed as part of this project. It is concluded that the technical problems raised by distributed solar systems are surmountable, but their resolution may be costly. The stringent purchase criteria likely to be imposed by many potential system users and the economies of large-scale systems make small systems (less than 10 to 20 kW) less attractive than larger systems. Utilities that consider life-cycle costs in making investment decisions and third-party investors who have tax and financial advantages are likely to place the highest value on solar-power systems.
Nuclear parton distributions from the nCTEQ group
Kusina, A
2016-01-01
We present the nCTEQ15 global analysis of nuclear parton distribution functions (nPDFs). The main addition to the previous nCTEQ PDFs is the introduction of PDF uncertainties based on the Hessian method. Another important improvement is the inclusion of pion production data from RHIC giving us a handle to constrain gluon PDF. In this presentation we briefly discuss the framework of our analysis and concentrate on the comparison of our results with those of other groups. Additionally we show a first estimate of the impact of the LHC pPb W/Z boson production data on the presented nCTEQ15 PDFs.
Power Management and Distribution (PMAD) Model Development: Final Report
Metcalf, Kenneth J.
2011-01-01
Power management and distribution (PMAD) models were developed in the early 1990's to model candidate architectures for various Space Exploration Initiative (SEI) missions. They were used to generate "ballpark" component mass estimates to support conceptual PMAD system design studies. The initial set of models was provided to NASA Lewis Research Center (since renamed Glenn Research Center) in 1992. They were developed to estimate the characteristics of power conditioning components predicted to be available in the 2005 timeframe. Early 90's component and device designs and material technologies were projected forward to the 2005 timeframe, and algorithms reflecting those design and material improvements were incorporated into the models to generate mass, volume, and efficiency estimates for circa 2005 components. The models are about ten years old now and NASA GRC requested a review of them to determine if they should be updated to bring them into agreement with current performance projections or to incorporate unforeseen design or technology advances. This report documents the results of this review and the updated power conditioning models and new transmission line models generated to estimate post 2005 PMAD system masses and sizes. This effort continues the expansion and enhancement of a library of PMAD models developed to allow system designers to assess future power system architectures and distribution techniques quickly and consistently.
Model-Free Optimal Control of Distributed Energy Resources in Electric Power Distribution Systems
Arnold, Daniel Brian
2015-01-01
Distributed Energy Resources (DER) have the potential to both improve the manner in which the electric power distribution system is operated and provide services to the bulk electric grid. A key question that has emerged in academic circles is the manner in which DER is governed to provide such utility. While many of the suggested approaches are mathematically elegant and demonstrate positive performance in simulations, they face enormous barriers to implementation due to their reliance on ...
2010-06-23
... Energy Regulatory Commission Resale Power Group of Iowa, WPPI Energy v. ITC Midwest LLC, Interstate Power and Light Company; Notice of Filing June 16, 2010. Take notice that, on June 15, 2010, Resale Power Group of Iowa and WPPI Energy filed a supplement to its complaint originally filed on May 18, 2010....
Analytical method for reconstruction pin to pin of the nuclear power density distribution
Energy Technology Data Exchange (ETDEWEB)
Pessoa, Paulo O.; Silva, Fernando C.; Martinez, Aquilino S., E-mail: ppessoa@con.ufrj.br, E-mail: fernando@con.ufrj.br, E-mail: aquilino@imp.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil)
2013-07-01
An accurate and efficient method for reconstructing pin to pin of the nuclear power density distribution, involving the analytical solution of the diffusion equation for two-dimensional neutron energy groups in homogeneous nodes, is presented. The boundary conditions used for analytic as solution are the four currents or fluxes on the surface of the node, which are obtained by Nodal Expansion Method (known as NEM) and four fluxes at the vertices of a node calculated using the finite difference method. The analytical solution found is the homogeneous distribution of neutron flux. Detailed distributions pin to pin inside a fuel assembly are estimated by the product of homogeneous flux distribution by local heterogeneous form function. Furthermore, the form functions of flux and power are used. The results obtained with this method have a good accuracy when compared with reference values. (author)
Risky Group Decision-Making Method for Distribution Grid Planning
Li, Cunbin; Yuan, Jiahang; Qi, Zhiqiang
2015-12-01
With rapid speed on electricity using and increasing in renewable energy, more and more research pay attention on distribution grid planning. For the drawbacks of existing research, this paper proposes a new risky group decision-making method for distribution grid planning. Firstly, a mixing index system with qualitative and quantitative indices is built. On the basis of considering the fuzziness of language evaluation, choose cloud model to realize "quantitative to qualitative" transformation and construct interval numbers decision matrices according to the "3En" principle. An m-dimensional interval numbers decision vector is regarded as super cuboids in m-dimensional attributes space, using two-level orthogonal experiment to arrange points uniformly and dispersedly. The numbers of points are assured by testing numbers of two-level orthogonal arrays and these points compose of distribution points set to stand for decision-making project. In order to eliminate the influence of correlation among indices, Mahalanobis distance is used to calculate the distance from each solutions to others which means that dynamic solutions are viewed as the reference. Secondly, due to the decision-maker's attitude can affect the results, this paper defines the prospect value function based on SNR which is from Mahalanobis-Taguchi system and attains the comprehensive prospect value of each program as well as the order. At last, the validity and reliability of this method is illustrated by examples which prove the method is more valuable and superiority than the other.
Enhanced power quality based single phase photovoltaic distributed generation system
Panda, Aurobinda; Pathak, M. K.; Srivastava, S. P.
2016-08-01
This article presents a novel control strategy for a 1-ϕ 2-level grid-tie photovoltaic (PV) inverter to enhance the power quality (PQ) of a PV distributed generation (PVDG) system. The objective is to obtain the maximum benefits from the grid-tie PV inverter by introducing current harmonics as well as reactive power compensation schemes in its control strategy, thereby controlling the PV inverter to achieve multiple functions in the PVDG system such as: (1) active power flow control between the PV inverter and the grid, (2) reactive power compensation, and (3) grid current harmonics compensation. A PQ enhancement controller (PQEC) has been designed to achieve the aforementioned objectives. The issue of underutilisation of the PV inverter in nighttime has also been addressed in this article and for the optimal use of the system; the PV inverter is used as a shunt active power filter in nighttime. A prototype model of the proposed system is developed in the laboratory, to validate the effectiveness of the control scheme, and is tested with the help of the dSPACE DS1104 platform.
Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation
Energy Technology Data Exchange (ETDEWEB)
David Deangelis; Rich Depuy; Debashis Dey; Georgia Karvountzi; Nguyen Minh; Max Peter; Faress Rahman; Pavel Sokolov; Deliang Yang
2004-09-30
This report summarizes the work performed by Hybrid Power Generation Systems, LLC (HPGS) during the April to October 2004 reporting period in Task 2.3 (SOFC Scaleup for Hybrid and Fuel Cell Systems) under Cooperative Agreement DE-FC26-01NT40779 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL), entitled ''Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation''. This study analyzes the performance and economics of power generation systems for central power generation application based on Solid Oxide Fuel Cell (SOFC) technology and fueled by natural gas. The main objective of this task is to develop credible scale up strategies for large solid oxide fuel cell-gas turbine systems. System concepts that integrate a SOFC with a gas turbine were developed and analyzed for plant sizes in excess of 20 MW. A 25 MW plant configuration was selected with projected system efficiency of over 65% and a factory cost of under $400/kW. The plant design is modular and can be scaled to both higher and lower plant power ratings. Technology gaps and required engineering development efforts were identified and evaluated.
Distributed interactive communication in simulated space-dwelling groups.
Brady, Joseph V; Hienz, Robert D; Hursh, Steven R; Ragusa, Leonard C; Rouse, Charles O; Gasior, Eric D
2004-03-01
This report describes the development and preliminary application of an experimental test bed for modeling human behavior in the context of a computer generated environment to analyze the effects of variations in communication modalities, incentives and stressful conditions. In addition to detailing the methodological development of a simulated task environment that provides for electronic monitoring and recording of individual and group behavior, the initial substantive findings from an experimental analysis of distributed interactive communication in simulated space dwelling groups are described. Crews of three members each (male and female) participated in simulated "planetary missions" based upon a synthetic scenario task that required identification, collection, and analysis of geologic specimens with a range of grade values. The results of these preliminary studies showed clearly that cooperative and productive interactions were maintained between individually isolated and distributed individuals communicating and problem-solving effectively in a computer-generated "planetary" environment over extended time intervals without benefit of one another's physical presence. Studies on communication channel constraints confirmed the functional interchangeability between available modalities with the highest degree of interchangeability occurring between Audio and Text modes of communication. The effects of task-related incentives were determined by the conditions under which they were available with Positive Incentives effectively attenuating decrements in performance under stressful time pressure.
Equality versus differentiation: the effects of power dispersion on group interaction.
Greer, Lindred L; van Kleef, Gerben A
2010-11-01
Power is an inherent characteristic of social interaction, yet research has yet to fully explain what power and power dispersion may mean for conflict resolution in work groups. We found in a field study of 42 organizational work groups and a laboratory study of 40 negotiating dyads that the effects of power dispersion on conflict resolution are contingent on the level of interactants' power, thereby explaining contradictory theory and findings on power dispersion. We found that when members have low power, power dispersion is positively related to conflict resolution, but when members have high power, power dispersion is negatively related to conflict resolution (i.e., power equality is better). These findings can be explained by the mediating role of intragroup power struggles. Together, these findings suggest that power hierarchies function as a heuristic solution for conflict and contribute to adaptive social dynamics in groups with low, but not high, levels of power.
Energy Technology Data Exchange (ETDEWEB)
1993-12-31
Reports on soldier power R&D review, N-MCT power electronic building blocks, silicon carbide power semiconductor work, and ground based radar were made to the Power Conditioning Panel. An introduction to high temperature electronics needs, research and development was made to the High Temperature Electronics Subcommittee. The Pulse Power Panel received reports on the navy ETC gun, and army pulse power. The Superconductivity Panel received reports on high-tc superconducting wires, superconducting magnetic energy storage, and superconducting applications. The Nuclear Working Group received presentations on the Topaz nuclear power program, and space nuclear work in the Department of Energy.
Time series power flow analysis for distribution connected PV generation.
Energy Technology Data Exchange (ETDEWEB)
Broderick, Robert Joseph; Quiroz, Jimmy Edward; Ellis, Abraham; Reno, Matthew J.; Smith, Jeff; Dugan, Roger
2013-01-01
Distributed photovoltaic (PV) projects must go through an interconnection study process before connecting to the distribution grid. These studies are intended to identify the likely impacts and mitigation alternatives. In the majority of the cases, system impacts can be ruled out or mitigation can be identified without an involved study, through a screening process or a simple supplemental review study. For some proposed projects, expensive and time-consuming interconnection studies are required. The challenges to performing the studies are twofold. First, every study scenario is potentially unique, as the studies are often highly specific to the amount of PV generation capacity that varies greatly from feeder to feeder and is often unevenly distributed along the same feeder. This can cause location-specific impacts and mitigations. The second challenge is the inherent variability in PV power output which can interact with feeder operation in complex ways, by affecting the operation of voltage regulation and protection devices. The typical simulation tools and methods in use today for distribution system planning are often not adequate to accurately assess these potential impacts. This report demonstrates how quasi-static time series (QSTS) simulation and high time-resolution data can be used to assess the potential impacts in a more comprehensive manner. The QSTS simulations are applied to a set of sample feeders with high PV deployment to illustrate the usefulness of the approach. The report describes methods that can help determine how PV affects distribution system operations. The simulation results are focused on enhancing the understanding of the underlying technical issues. The examples also highlight the steps needed to perform QSTS simulation and describe the data needed to drive the simulations. The goal of this report is to make the methodology of time series power flow analysis readily accessible to utilities and others responsible for evaluating
Integration of Small Solar tower Systems into Distributed Power Islands
Energy Technology Data Exchange (ETDEWEB)
Romero, M.; Marcos, M. J.; Tellez, F. M.; Blanco, M.; Fernandez, V.; Baonza, F.; Berger, S. [Ciemat, Madrid (Spain)
2000-07-01
One of the short-term priorities for renewable energies in Europe is their integration for local power supply into communities and energy islands (blocks of buildings, new neighborhoods in residential areas, shopping centers, hospitals, recreational areas, eco-paks, small rural areas or isolated ones such as islands or mountain communities). Following this strategy, the integration of small tower fields into so-called MIUS (Modular Integrated Utility Systems) is proposed. This application strongly influences field concepts leadings to modular multi-tower systems able to more closely track demand, meet reliability requirements with fewer megawatts of installed power and spread construction costs over time after output has begum. In addition, integration into single-cycle high-efficiency gas turbines plus waste-heat applications clearly increments the solar share. The chief questions are whether solar towers can be redesigned for such distributed markets and the keys to their feasibility. This paper includes the design and performance analysis of a 1.36-MW plant and integration in the MIUS system, as well as the expected cost of electricity and a sensitivity analysis of the small tower plant's performance with design parameters like heliostat configuration and tower height. A practical application is analyzed for a shopping center with 85% power demand during day-time by using a hybrid solar tower and a gas turbine producing electricity and waste heat for hot water and heating and cooling of spaces. The operation mode proposed is covering night demand with power from the grid and solar-gas power island mode during 14 hours daytime with a maximum power production of 1.36 MW. (Author) 26 refs.
A distributed control approach for power and energy management in a notional shipboard power system
Shen, Qunying
The main goal of this thesis is to present a power control module (PCON) based approach for power and energy management and to examine its control capability in shipboard power system (SPS). The proposed control scheme is implemented in a notional medium voltage direct current (MVDC) integrated power system (IPS) for electric ship. To realize the control functions such as ship mode selection, generator launch schedule, blackout monitoring, and fault ride-through, a PCON based distributed power and energy management system (PEMS) is developed. The control scheme is proposed as two-layer hierarchical architecture with system level on the top as the supervisory control and zonal level on the bottom as the decentralized control, which is based on the zonal distribution characteristic of the notional MVDC IPS that was proposed as one of the approaches for Next Generation Integrated Power System (NGIPS) by Norbert Doerry. Several types of modules with different functionalities are used to derive the control scheme in detail for the notional MVDC IPS. Those modules include the power generation module (PGM) that controls the function of generators, the power conversion module (PCM) that controls the functions of DC/DC or DC/AC converters, etc. Among them, the power control module (PCON) plays a critical role in the PEMS. It is the core of the control process. PCONs in the PEMS interact with all the other modules, such as power propulsion module (PPM), energy storage module (ESM), load shedding module (LSHED), and human machine interface (HMI) to realize the control algorithm in PEMS. The proposed control scheme is implemented in real time using the real time digital simulator (RTDS) to verify its validity. To achieve this, a system level energy storage module (SESM) and a zonal level energy storage module (ZESM) are developed in RTDS to cooperate with PCONs to realize the control functionalities. In addition, a load shedding module which takes into account the reliability
Application of Distribution Power Electronic Transformer for Medium Voltage
Directory of Open Access Journals (Sweden)
Prashant Kumar
2014-12-01
Full Text Available In this paper a distribution power electronic transformer (DPET for feeding critical loads is presented. The PE based transformer is a multi-port converter that can connect to medium voltage levels on the primary side. Bidirectional power flow is provided to the each module. The presented structure consists of three stages: an input stage, an isolation stage, and an output stage. The input current is sinusoidal, and it converts the high AC input voltage to low DC voltages. The isolated DC/DC converters are then connected to the DC links and provide galvanic isolation between the HV and LV sides. Finally, a three-phase inverter generates the AC output with the desired amplitude and frequency. The proposed DPET is extremely modular and can be extended for different voltage and power levels. It performs typical functions and has advantages such as power factor correction, elimination of voltage sag and swell, and reduction of voltage flicker in load side. Also in comparison to conventional transformers, it has lower weight, lower volume and eliminates necessity for toxic dielectric coolants the DPET performance is verified in MATLAB simulation.
Expert Group Meeting on Population Distribution and Migration.
1993-01-01
As part of the preparation for the up-coming International Conference on Population and Development, an expert group meeting on population distribution and migration was held in Santa Cruz, Bolivia, in January 1993. Participants considered the scope of migration which included a net internal migration of between 75 million and 1 billion people during 1975-85 and international migration which census data put at 77 million in the 1970s and early 1980s. World economic trends during the 1980s were reviewed, as were changes in the nature and configuration of various countries. The following topics were explored: patterns of population distribution and development, policies affecting internal migration and population distribution, internal migration and its implications for development, economic aspects of international migration, international migration in a changing world, international migration between developing countries, and refugees and asylum-seekers. 37 recommendations were prepared for governments, social institutions, and the international community. The first 10 urge that population distribution be an integral part of development policies, that government policies and expenditures be evaluated for their contribution to social and economic goals, that the capacity and competence of municipal authorities to manage urban development be increased, that government funding be decentralized, that economic and institutional links be developed between urban centers and surrounding rural areas, that alternatives to out-migration from rural areas be created, that the income-earning capacities of migrants be improved, that group mobilization by and for people affected by migration be encouraged, that adequate access to health services and family planning be assured, and that the underlying causes of environmental degradation, natural disasters, and war be addressed with mechanisms developed to protect victims. 13 recommendations deal with international migration and
Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation
Energy Technology Data Exchange (ETDEWEB)
Faress Rahman; Nguyen Minh
2004-01-04
This report summarizes the work performed by Hybrid Power Generation Systems, LLC (HPGS) during the July 2003 to December 2003 reporting period under Cooperative Agreement DE-FC26-01NT40779 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation''. The main objective of this project is to develop and demonstrate the feasibility of a highly efficient hybrid system integrating a planar Solid Oxide Fuel Cell (SOFC) and a micro-turbine. In addition, an activity included in this program focuses on the development of an integrated coal gasification fuel cell system concept based on planar SOFC technology. Also, another activity included in this program focuses on the development of SOFC scale up strategies.
The influence of bromazepam on cortical power distribution.
Sampaio, Isabel; Puga, Fernanda; Veiga, Heloisa; Cagy, Mauricio; Piedade, Roberto; Ribeiro, Pedro
2008-06-01
The EEG has been widely employed in the assessment of electrophysiological changes induced by distinct medications. Its sensibility in detecting alterations produced by a specific substance may be enhanced by methods of quantitative analyses (qEEG). The present study aimed at investigating the modulatory effects of bromazepam on brain dynamics. The effects of bromazepam (3 mg) on EEG power distribution were tested in 10 healthy individuals, in a double-blind experiment. The electrophysiological measure was analyzed across experimental conditions, moments, and electrodes, in the delta, theta, alpha and beta frequency bands separately. A significant decrease of relative power was observed in delta and theta (main effect of condition). No interactions were observed. Although the expected anxiolytic EEG profile was not observed (increased beta and decreased alpha activity), this specific result may be related to other factors such as dosage used and the subjects' general physiological state, and not necessarily to the drug itself.
On Certain Distributive Lattices of Subgroups of Finite Soluble Groups
Institute of Scientific and Technical Information of China (English)
L.M.EZQUERRO; X. SOLER-ESCRIV(A)
2007-01-01
In this paper, we prove the following result. Let (S) be a saturated formation and ∑ a Hall system of a soluble group G. Let X be a w-solid set of maximal subgroups of G such that ∑ reduces into each element of X. Consider in G the following three subgroups: the (S)-normalizer D of G associated with ∑; the X-prefrattini subgroup W = W(G, X) of G; and a hypercentrally embedded subgroup T of G. Then the lattice (ε)(T, W, D) generated by T, D and W is a distributive lattice of pairwise permutable subgroups of G with the cover and avoidance property.This result remains true for the lattice (ε)(V, W, D), where V is a subgroup of G whose Sylow subgroups are also Sylow subgroups of hypercentrally embedded subgroups of G such that ∑ reduces into V.
Environmental distribution, abundance and activity of the Miscellaneous Crenarchaeotal Group
Lloyd, K. G.; Biddle, J.; Teske, A.
2011-12-01
Many marine sedimentary microbes have only been identified by 16S rRNA sequences. Consequently, little is known about the types of metabolism, activity levels, or relative abundance of these groups in marine sediments. We found that one of these uncultured groups, called the Miscellaneous Crenarchaeotal Group (MCG), dominated clone libraries made from reverse transcribed 16S rRNA, and 454 pyrosequenced 16S rRNA genes, in the White Oak River estuary. Primers suitable for quantitative PCR were developed for MCG and used to show that 16S rRNA DNA copy numbers from MCG account for nearly all the archaeal 16S rRNA genes present. RT-qPCR shows much less MCG rRNA than total archaeal rRNA, but comparisons of different primers for each group suggest bias in the RNA-based work relative to the DNA-based work. There is no evidence of a population shift with depth below the sulfate-methane transition zone, suggesting that the metabolism of MCG may not be tied to sulfur or methane cycles. We classified 2,771 new sequences within the SSU Silva 106 database that, along with the classified sequences in the Silva database was used to make an MCG database of 4,646 sequences that allowed us to increase the named subgroups of MCG from 7 to 19. Percent terrestrial sequences in each subgroup is positively correlated with percent of the marine sequences that are nearshore, suggesting that membership in the different subgroups is not random, but dictated by environmental selective pressures. Given their high phylogenetic diversity, ubiquitous distribution in anoxic environments, and high DNA copy number relative to total archaea, members of MCG are most likely anaerobic heterotrophs who are integral to the post-depositional marine carbon cycle.
Electrical power transmission and distribution aging and life extension techniques
Chudnovsky, Bella H
2012-01-01
""The focus of this unique reference book is four critical areas in the manufacturing of power distribution components. These areas are plating, lubrication, insulator failure, and maintenance. ... The many SEM images, x-ray studies, photos, and tabular data make for a very convenient reference source for diagnosing plating problems. ... Examples often help to drive home a point, and many case studies illustrating the various failure modes described throughout the book are included. These could prove to be an invaluable source of information when trying to diagnose unknown field failures. ...
EMC and power quality standards for 20-kHz power distribution
Hansen, Irving G.
1987-01-01
The Space Station Power Distribution System has been baselined as a sinusoidal single phase, 440 VRMS system. This system has certain unique characteristics directly affecting its application. In particular, existing systematic description and control documents were modified to reflect the high operating frequency. This paper will discuss amendments made on Mil STD 704 (Electrical Power Characteristics), and Mil STD 461-B (Electromagnetic Emission and Susceptibility Requirements for the Control of Electromagnetic Interference). In some cases these amendments reflect changes of several orders of magnitude. Implications and impacts of these changes are discussed.
Garanina, O S
2016-01-01
A multi-parametric family of stretch exponential distributions with various power law tails is introduced and is shown to describe adequately the empirical distributions of scientific citation of individual authors. The four-parametric families are characterized by a normalization coefficient in the exponential part, the power exponent in the power-law asymptotic part, and the coefficient for the transition between the above two parts. The distribution of papers of individual scientist over citations of these papers is studied. Scientists are selected via total number of citations in three ranges: 102-103, 103-104, and 104-105 of total citations. We study these intervals for physicists in ISI Web of Knowledge. The scientists who started their scientific publications after 1980 were taken into consideration only. It is detected that the power coefficient in the stretch exponent starts from one for low-cited authors and has to trend to smaller values for scientists with large number of citation. At the same tim...
A Sufficient Condition on Convex Relaxation of AC Optimal Power Flow in Distribution Networks
DEFF Research Database (Denmark)
Huang, Shaojun; Wu, Qiuwei; Wang, Jianhui;
2016-01-01
This paper proposes a sufficient condition for the convex relaxation of AC Optimal Power Flow (OPF) in radial distribution networks as a second order cone program (SOCP) to be exact. The condition requires that the allowed reverse power flow is only reactive or active, or none. Under the proposed...... sufficient condition, the feasible sub-injection region (power injections of nodes excluding the root node) of the AC OPF is convex. The exactness of the convex relaxation under the proposed condition is proved through constructing a group of monotonic series with limits, which ensures that the optimal...... solution of the SOCP can be converted to an optimal solution of the original AC OPF. The efficacy of the convex relaxation to solve the AC OPF is demonstrated by case studies of an optimal multi-period planning problem of electric vehicles (EVs) in distribution networks....
A Sufficient Condition on Convex Relaxation of AC Optimal Power Flow in Distribution Networks
DEFF Research Database (Denmark)
Huang, Shaojun; Wu, Qiuwei; Wang, Jianhui
2016-01-01
This paper proposes a sufficient condition for the convex relaxation of AC Optimal Power Flow (OPF) in radial distribution networks as a second order cone program (SOCP) to be exact. The condition requires that the allowed reverse power flow is only reactive or active, or none. Under the proposed...... sufficient condition, the feasible sub-injection region (power injections of nodes excluding the root node) of the AC OPF is convex. The exactness of the convex relaxation under the proposed condition is proved through constructing a group of monotonic series with limits, which ensures that the optimal...... solution of the SOCP can be converted to an optimal solution of the original AC OPF. The efficacy of the convex relaxation to solve the AC OPF is demonstrated by case studies of an optimal multi-period planning problem of electric vehicles (EVs) in distribution networks....
Gaussian distributions, Jacobi group, and Siegel-Jacobi space
Energy Technology Data Exchange (ETDEWEB)
Molitor, Mathieu, E-mail: pergame.mathieu@gmail.com [Instituto de Matemática, Universidade Federal da Bahia, Av. Adhemar de Barros, S/N, Ondina, 40170-110 Salvador, BA (Brazil)
2014-12-15
Let N be the space of Gaussian distribution functions over ℝ, regarded as a 2-dimensional statistical manifold parameterized by the mean μ and the deviation σ. In this paper, we show that the tangent bundle of N, endowed with its natural Kähler structure, is the Siegel-Jacobi space appearing in the context of Number Theory and Jacobi forms. Geometrical aspects of the Siegel-Jacobi space are discussed in detail (completeness, curvature, group of holomorphic isometries, space of Kähler functions, and relationship to the Jacobi group), and are related to the quantum formalism in its geometrical form, i.e., based on the Kähler structure of the complex projective space. This paper is a continuation of our previous work [M. Molitor, “Remarks on the statistical origin of the geometrical formulation of quantum mechanics,” Int. J. Geom. Methods Mod. Phys. 9(3), 1220001, 9 (2012); M. Molitor, “Information geometry and the hydrodynamical formulation of quantum mechanics,” e-print arXiv (2012); M. Molitor, “Exponential families, Kähler geometry and quantum mechanics,” J. Geom. Phys. 70, 54–80 (2013)], where we studied the quantum formalism from a geometric and information-theoretical point of view.
An Efficient Distributed Power Control in Cognitive Radio Networks
Directory of Open Access Journals (Sweden)
Mohammad Hossein Faridi
2016-01-01
Full Text Available In cognitive radio networks, when primary users (PUs do not use a shared frequency band, secondary users (SUs are allowed to use that frequency band. However, when SU using frequency band and reclaiming PU also wants to use this band, there are two solutions: SU jumps to another existing spectrum band or stays in the same frequency band and changes its power so that interference in the reclaiming PUs does not exceed a threshold. Since the first solution interrupts the SUs' work, the second solution is more appropriate. Therefore, power control in cognitive networks is absolutely significant which should receive more attention. In the previous work (TPC-CBS [2], TPC algorithm has been used for power control. The drawback of this algorithm is fixed target SIRs. In other words, while using this algorithm, all the users having enough sources or extra sources reach the same target SIR, which is not desirable. Therefore, in this paper, we are going to solve it by means of the proposed algorithm called "An Efficient Distributed Power Control Algorithm for Cognitive Networks (EDPC". By the proposed algorithm, when a user has a bad channel, its SIR sets to the minimum target SIR and, when it has a good channel, its SIR will be more than the minimum value. Moreover, by means of fuzzy logic systems (FLS, the value of interference on reclaiming PU caused by SUs is checked in each iteration and power level of SUs is decreased if this value exceeds a threshold. Simulation results show that using our proposed algorithm not only allows SUs and PUs use frequency band simultaneously, but also enhances throughput significantly in comparison with the previous approaches (TPC-CBS.
Multi-group pin power reconstruction method based on colorset form functions
Institute of Scientific and Technical Information of China (English)
HUANG Hao
2009-01-01
A multi-group pin power reconstruction method that fully exploits nodal information obtained from global coarse mesh solution has been developed.It expands the intra-nodal flux distributions into nonseparable semi-analytic basis functions,and a colorset based form function generating method is proposed,which can accurately model the spectral interaction occurring at assembly interface.To demonstrate its accuracy and applicability to realistic problems,the new method is tested against two benchmark problems,including a mixed-oxide fuel problem.The results show that the new method is comparable in accuracy to fine-mesh methods.
The Relationship of Between Fuzzy Power Groups and Fuzzy Quotient Groups%Fuzzy幂群与Fuzzy商群的相互关系
Institute of Scientific and Technical Information of China (English)
闫广霞; 米洪海; 施雅婷
2006-01-01
In this paper, we extend the concept of fuzzy quotient groups. The structures of fuzzy power groups and fuzzy quotient groups are discussed. The relationship between fuzzy power groups and fuzzy quotient groups are considered.
Asynchronous Group Key Distribution on top of the CC2420 Security Mechanisms for Sensor Networks
DEFF Research Database (Denmark)
Hansen, Morten Tranberg
2009-01-01
scheme with no time synchronization requirements. The scheme decreases the number of key updates by providing them on an as needed basis according to the amount of network traffic. We evaluate the CC2420 radio security mechanism and show how to use it as a basis to implement secure group communication......A sensor network is a network consisting of small, inexpensive, low-powered sensor nodes that communicate to complete a common task. Sensor nodes are characterized by having limited communication and computation capabilities, energy, and storage. They often are deployed in hostile environments...... creating a demand for encryption and authentication of the messages sent between them. Due to severe resource constraints on the sensor nodes, efficient key distribution schemes and secure communication protocols with low overhead are desired. In this paper we present an asynchronous group key distribution...
Protostellar fragmentation in a power-law density distribution
Burkert, A; Bodenheimer, P
1997-01-01
Hydrodynamical calculations in three space dimensions of the collapse of an isothermal, rotating 1 M\\sol protostellar cloud are presented. The initial density stratification is a power law with density $\\rho \\propto r^{-p}$, with $p=1$. The case of the singular isothermal sphere ($p=2$) is not considered; however $p=1$ has been shown observationally to be a good representation of the density distribution in molecular cloud cores just before the beginning of collapse. The collapse is studied with two independent numerical methods, an SPH code with 200,000 particles, and a finite-difference code with nested grids which give high spatial resolution in the inner regions. Although previous numerical studies have indicated that such a power-law distribution would not result in fragmentation into a binary system, both codes show, in contrast, that multiple fragmentation does occur in the central regions of the protostar. Thus the process of binary formation by fragmentation is shown to be consistent with the fact th...
Directory of Open Access Journals (Sweden)
F. Gharedaghi
2012-03-01
Full Text Available The large number of decision variables of long-term planning problem for improving the distribution system causes lots of complexities. The optimum allocation of Distributed Generation (DG sources and determining their capacity in the deregulated electric market is a key way for capacity expansion of the distribution firm. In this study, a new approach is presented to determination the optimum location and capacity of DG sources in the deregulated electric market through the net present value analysis using an optimization model. This model aims to minimize the investment cost of the distribution firm, utility cost and the losses cost considering the anticipated load peak value. Considering the power market price anticipation to be indefinite, the proposed method is based on laying out the genetic algorithm and a fuzzy model to the power market price and the capacity expansion design of the distribution system during different time intervals is proposed along with two static and semi-dynamic methods. The efficiency of the proposed approach is well shown applying it to a sample network.
Power Quality Issues In Indian Power Distribution Utilities And Feasible Solutions
Directory of Open Access Journals (Sweden)
Narasimha Pandit
2015-08-01
Full Text Available One important contributing factor to Indias slow pace of development in general and relatively poor industrial growth in particular is the poor quality and reliability of the electrical power. Earlier the consumers of electrical energy were mere acceptors. Interruptions and other voltage disturbances were part of the deal. But today electric power is viewed as a product with certain characteristics which can be measured predicted guaranteed improved etc. which has become an integral part of our life. This paper gives insights on different Power Quality PQ problems experienced by the Indian electricity consumers and the reasons for those problems. This paper proposes feasible solutions to assist in employing or implementing appropriate mitigation techniques with an optimism of an improvement in the field scenario as more and more investments are proposed in Generation Transmission and Distribution Sectors and stringent codes and standards are being imposed for those who do not maintain minimum PQ level in the field.
Fuel cycle comparison of distributed power generation technologies.
Energy Technology Data Exchange (ETDEWEB)
Elgowainy, A.; Wang, M. Q.; Energy Systems
2008-12-08
The fuel-cycle energy use and greenhouse gas (GHG) emissions associated with the application of fuel cells to distributed power generation were evaluated and compared with the combustion technologies of microturbines and internal combustion engines, as well as the various technologies associated with grid-electricity generation in the United States and California. The results were primarily impacted by the net electrical efficiency of the power generation technologies and the type of employed fuels. The energy use and GHG emissions associated with the electric power generation represented the majority of the total energy use of the fuel cycle and emissions for all generation pathways. Fuel cell technologies exhibited lower GHG emissions than those associated with the U.S. grid electricity and other combustion technologies. The higher-efficiency fuel cells, such as the solid oxide fuel cell (SOFC) and molten carbonate fuel cell (MCFC), exhibited lower energy requirements than those for combustion generators. The dependence of all natural-gas-based technologies on petroleum oil was lower than that of internal combustion engines using petroleum fuels. Most fuel cell technologies approaching or exceeding the DOE target efficiency of 40% offered significant reduction in energy use and GHG emissions.
Application of PowerBuilder User Objects in Developing Distributed Programs
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
User Objects are the basement in developing distributed PowerBuilder applications. There are two kinds of PowerBuilder objects: visual objects and non-visual objects. Usually we use non-visual objects to perform the PowerBuilder distriuted application. This paper introduces the method of developing PowerBuilder distributed application program,mainly discusses the application of nonvisual objects when developing PowerBuilder distributed application programs.
Prediction of reserves using multivariate power-normal mixture distribution
Ling, Ang Siew; Hin, Pooi Ah
2016-10-01
Recently, in the area on stochastic loss reserving, there are a number of papers which analyze the individual claims data using the Position Dependent Marked Poisson Process. The present paper instead uses a different type of individual data. For the i-th (1≤i≤n) customer, these individual data include the sum insured si together with the amount paid yi j and the amount ai j reported but not yet paid in the j-th (1 ≤ j ≤ 6) development year. A technique based on multivariate power-normal mixture distribution is already available for predicting the future value (yi j + 1, ai j + 1) using the present year value (yi j, ai j) and the sum insured si. Presently the above technique is improved by the transformation of distribution which is defined on the whole real line to one which is non-negative and having approximately the same first four moments as the original distribution. It is found that, for the dataset considered in this paper, the improved method gives a better estimate for the reserve when compared with the chain ladder reserve estimate. Furthermore, the method is expected to provide a fairly reliable value for the Provision of Risk Margin for Adverse Deviation (PRAD).
The radial distribution of galaxies in groups and clusters
Budzynski, J M; McCarthy, I G; McGee, S L; Belokurov, V
2012-01-01
We present a new catalogue of 55,121 groups and clusters centred on Luminous Red Galaxies from SDSS DR7 in the redshift range 0.15~2.6) that is approximately a factor of two lower than that of the dark matter (as predicted by N-body cosmological simulations) and nearly independent of halo mass. Interestingly, in spite of the difference in shape between the galaxy and dark matter radial distributions, both exhibit a high degree of self-similarity. A self-consistent comparison to several recent semi-analytic models of galaxy formation indicates that: (1) beyond ~0.3 r_500 current models are able to reproduce both the shape and normalisation of the satellite profiles; and (2) within ~0.3 r_500 the predicted profiles are sensitive to the details of the satellite-BCG merger timescale calculation. The former is a direct result of the models being tuned to match the global galaxy luminosity function combined with the assumption that the satellite galaxies do not suffer significant tidal stripping, even though their ...
Designing a Repetitive Group Sampling Plan for Weibull Distributed Processes
Directory of Open Access Journals (Sweden)
Aijun Yan
2016-01-01
Full Text Available Acceptance sampling plans are useful tools to determine whether the submitted lots should be accepted or rejected. An efficient and economic sampling plan is very desirable for the high quality levels required by the production processes. The process capability index CL is an important quality parameter to measure the product quality. Utilizing the relationship between the CL index and the nonconforming rate, a repetitive group sampling (RGS plan based on CL index is developed in this paper when the quality characteristic follows the Weibull distribution. The optimal plan parameters of the proposed RGS plan are determined by satisfying the commonly used producer’s risk and consumer’s risk at the same time by minimizing the average sample number (ASN and then tabulated for different combinations of acceptance quality level (AQL and limiting quality level (LQL. The results show that the proposed plan has better performance than the single sampling plan in terms of ASN. Finally, the proposed RGS plan is illustrated with an industrial example.
Models and Methods for Urban Power Distribution Network Planning
Institute of Scientific and Technical Information of China (English)
余贻鑫; 王成山; 葛少云; 肖俊; 严雪飞; 黄纯华
2004-01-01
The models, methods and their application experiences of a practical GIS(geographic information system)-based computer decision-making support system of urban power distribution network planning with seven subsystems, termed CNP, are described. In each subsystem there is at least one or one set of practical mathematical methobs. Some new models and mathematical methods have been introduced. In the development of GNP the idea of cognitive system engineering has been insisted on, which claims that human and computer intelligence should be combined together to solve the complex engineering problems cooperatively. Practical applications have shown that not only the optimal plan can be automatically reached with many complicated factors considered, but also the computation,analysis and graphic drawing burden can be released considerably.
Unbalanced Load Simulation of Electronic Power Transformer in Distribution System
Institute of Scientific and Technical Information of China (English)
Wang Dan; Mao Chengxiong; Lu Jiming; Fan Shu; Cao Jiewei; Wang Ben
2006-01-01
A control scheme of electronic power transformer (EPT) in a three-phase four-wire distribution system, which included an input section, an isolating section and an output section, was researched under unbalanced loads. The simple and appropriate control scheme was developed through analyzing the system requirements of the primary side and the load requirements of the secondary side. In the input section, a dual-loop control in synchronous rotating d-q coordinates was introduced, and in the output section, a dual-loop control based on instantaneous output voltage wasused. Load characteristics of EPT were investigated by using Matlab/Simulink software. Simulation results showed that, with the proposed control scheme, the EPT has good performances and the sinusoidal input current and constant output voltage can be realized under both balanced and unbalanced loads.
Equality versus differentiation: the effects of power dispersion on group interaction
Greer, L.L.; van Kleef, G.A.
2010-01-01
Power is an inherent characteristic of social interaction, yet research has yet to fully explain what power and power dispersion may mean for conflict resolution in work groups. We found in a field study of 42 organizational work groups and a laboratory study of 40 negotiating dyads that the effects
C -parameter distribution at N3LL' including power corrections
Hoang, André H.; Kolodrubetz, Daniel W.; Mateu, Vicent; Stewart, Iain W.
2015-05-01
We compute the e+e- C -parameter distribution using the soft-collinear effective theory with a resummation to next-to-next-to-next-to-leading-log prime accuracy of the most singular partonic terms. This includes the known fixed-order QCD results up to O (αs3), a numerical determination of the two-loop nonlogarithmic term of the soft function, and all logarithmic terms in the jet and soft functions up to three loops. Our result holds for C in the peak, tail, and far tail regions. Additionally, we treat hadronization effects using a field theoretic nonperturbative soft function, with moments Ωn. To eliminate an O (ΛQCD) renormalon ambiguity in the soft function, we switch from the MS ¯ to a short distance "Rgap" scheme to define the leading power correction parameter Ω1. We show how to simultaneously account for running effects in Ω1 due to renormalon subtractions and hadron-mass effects, enabling power correction universality between C -parameter and thrust to be tested in our setup. We discuss in detail the impact of resummation and renormalon subtractions on the convergence. In the relevant fit region for αs(mZ) and Ω1, the perturbative uncertainty in our cross section is ≃ 2.5 % at Q =mZ.
Distributed power in Afghanistan: The Padisaw micro-hydro project
Energy Technology Data Exchange (ETDEWEB)
Hallett, Michael [Hallett and Associates, 4337 Coffman Blvd, Chesapeake, VA 23321 (United States)
2009-12-15
The provision of electricity is a vital need in reconstruction and development situations, like that in Afghanistan. Indeed, according to the Afghan government's Afghan National Development Strategy (ANDS) the need for electricity featured in 80% of the Provincial Development Plans as a top priority. With the help of the International Community, the government of Afghanistan is attempting to develop a new market oriented approach to the nationwide provision of electrical power. Although the bulk of the electrification effort is directed toward large scale construction of a national grid, the ANDS explicitly mentions a role for 'micro-hydro, solar, waste and small scale diesel power and energy generating sources'. This article will describe a micro-hydro project in Padisaw village, in the Nurgaram district of Nuristan province located in Northeastern Afghanistan and the role Provincial Reconstruction Team played in working with the local community through the project planning and building processes and offer some observation on how, as the Afghan National Development Strategy is executed, the private sector can play an increasingly significant role in the Afghan distributed energy arena. (author)
Power Law Distributions of Patents as Indicators of Innovation
O'Neale, D R J
2012-01-01
The total number of patents produced by a country (or the number of patents produced per capita) is often used as an indicator for innovation. Here we present evidence that the distribution of patents amongst applicants within many OECD countries is well-described by power laws with exponents that vary between 1.66 (Japan) and 2.37 (Poland). Using simulations based on simple preferential attachment-type rules that generate power laws, we find we can explain some of the variation in exponents between countries, with countries that have larger numbers of patents per applicant generally exhibiting smaller exponents in both the simulated and actual data. Similarly we find that the exponents for most countries are inversely correlated with other indicators of innovation, such as R&D intensity or the ubiquity of export baskets. This suggests that in more advanced economies, which tend to have smaller values of the exponent, a greater proportion of the total number of patents are filed by large companies than in...
Power law distributions of patents as indicators of innovation.
Directory of Open Access Journals (Sweden)
Dion R J O'Neale
Full Text Available The total number of patents produced by a country (or the number of patents produced per capita is often used as an indicator for innovation. Here we present evidence that the distribution of patents amongst applicants within many countries is well-described by power laws with exponents that vary between 1.66 (Japan and 2.37 (Poland. We suggest that this exponent is a useful new metric for studying innovation. Using simulations based on simple preferential attachment-type rules that generate power laws, we find we can explain some of the variation in exponents between countries, with countries that have larger numbers of patents per applicant generally exhibiting smaller exponents in both the simulated and actual data. Similarly we find that the exponents for most countries are inversely correlated with other indicators of innovation, such as research and development intensity or the ubiquity of export baskets. This suggests that in more advanced economies, which tend to have smaller values of the exponent, a greater proportion of the total number of patents are filed by large companies than in less advanced countries.
Distributed power from solar tower systems : a MIUS approach
Energy Technology Data Exchange (ETDEWEB)
Romero, M.; Marcos, M.J.; Tellez, F.M.; Blanco, M. [CIEMAT/DER-PSA, Madrid (Spain); Fernandez, V. [AICIA, Escuela Superior de Ingenieros, Seville (Spain); Baonza, F. [Escuela Politecnica Superior, Madrid (Spain). Dpto. Ingenieria Mecanica; Berger, S. [Ecole Nat. des Ponts et Chaussees, Marne-la-Vallee (France)
1999-07-01
One of the short-term priorities for renewable energies in Europe is their integration into communities and energy islands for local power supply (blocks of buildings, new neighborhoods in residential areas, shopping centers, hospitals, recreational areas, ecoparks, small rural areas or isolated ones such as islands or mountain communities). Following this strategy, the integration of small solar tower fields into so-called MIUS (Modular Integrated Utility Systems) is proposed. This application strongly influences field concepts leading to modular multi-tower systems able to more closely track demand, meet reliability requirements with fewer megawatts of installed power and spread construction costs over time after output has begun. In addition, integration into single-cycle high-efficiency gas turbines plus waste-heat applications clearly increments the solar share. The main questions are whether solar towers can be redesigned for such distributed markets and how to make them feasible. This paper includes the design and performance analysis of a 1.36 MW plant and its integration in the MIUS system, as well as the expected cost of electricity and a sensitivity analysis of the small tower plant's performance with design parameters like heliostat configuration and tower height. A practical application is analyzed for a shopping center with a solar tower producing electricity and waste heat for hot water and heating and cooling of spaces. (Author)
KANSAS WIND POWERING AMERICAN STATE OUTREACH: KANSAS WIND WORKING GROUP
Energy Technology Data Exchange (ETDEWEB)
HAMMARLUND, RAY
2010-10-27
The Kansas Wind Working Group (WWG) is a 33-member group announced by former Governor Kathleen Sebelius on Jan. 7, 2008. Formed through Executive Order 08-01, the WWG will educate stakeholder groups with the current information on wind energy markets, technologies, economics, policies, prospects and issues. Governor Mark Parkinson serves as chair of the Kansas Wind Working Group. The group has been instrumental in focusing on the elements of government and coordinating government and private sector efforts in wind energy development. Those efforts have moved Kansas from 364 MW of wind three years ago to over 1000 MW today. Further, the Wind Working Group was instrumental in fleshing out issues such as a state RES and net metering, fundamental parts of HB 2369 that was passed and is now law in Kansas. This represents the first mandatory RES and net metering in Kansas history.
Aging Management Guideline for commercial nuclear power plants: Power and distribution transformers
Energy Technology Data Exchange (ETDEWEB)
Toman, G.; Gazdzinski, R. [Sandia National Labs., Albuquerque, NM (United States)
1994-05-01
This Aging Management Guideline (AMG) provides recommended methods for effective detection and mitigation of age-related degradation mechanisms in power and distribution transformers important to license renewal in commercial nuclear power plants. The intent of this AMG to assist plant maintenance and operations personnel in maximizing the safe, useful life of these components. It also supports the documentation of effective aging management programs required under the License Renewal Rule 10 CFR Part 54. This AMG is presented in a manner which allows personnel responsible for performance analysis and maintenance to compare their plant-specific aging mechanisms (expected or already experienced) and aging management program activities to the more generic results and recommendations presented herein.
Directory of Open Access Journals (Sweden)
Amin Safari
2013-12-01
Full Text Available A new control scheme to improve the stability of a system by optimal design of distributed power flow controller (DPFC based stabilizer is presented in this paper. The paper demonstrates the basic module, steady state operation, mathematical analysis, and current injection modeling of the DPFC. The purpose of the work reported in this paper is to design an oscillation damping controller for DPFC to damp low frequency electromechanical oscillations. The optimal design problem is formulated as an optimization problem, and particle swarm optimization (PSO is employed to search for the damping controller parameters. Results demonstrate that DPFC with the proposed model can more effectively improve the dynamic stability and enhance the transient stability of power system compared to the genetic algorithm based damping controllers. The r and λ are relative magnitude and phase angle of DPFC controller. Moreover, the results show that the λ based controller is superior to the r based controller.
Group Search Optimization for Fixed Head Hydrothermal Power System
Jena, Chitralekha; Basu, Mousumi
2017-02-01
This paper presents group search optimization for optimal scheduling of thermal plants in coordination with fixed head hydro units. Numerical results for two test systems have been presented to demonstrate the performance of the proposed method. Results obtained from the proposed group search optimization method have been compared with those obtained from differential evolution and evolutionary programming.
Quintana Barcia, Pablo José
2016-01-01
This PhD Thesis, entitled “Power Electronic Supplies For Public Lighting Systems With Distributed Generation Capability: Solution Proposals For Power And Control Stages, Characterization And Minimization Of The Impact In Grid Quality”, has been developed as one of the core research activities of the Efficient Energy Conversion, Industrial Electronics and Lighting Engineering group (CE3I2), from the Electrical Engineering Department (DIEECS) of the University of Oviedo. This work targets th...
Power law olivine crystal size distributions in lithospheric mantle xenoliths
Armienti, P.; Tarquini, S.
2002-12-01
Olivine crystal size distributions (CSDs) have been measured in three suites of spinel- and garnet-bearing harzburgites and lherzolites found as xenoliths in alkaline basalts from Canary Islands, Africa; Victoria Land, Antarctica; and Pali Aike, South America. The xenoliths derive from lithospheric mantle, from depths ranging from 80 to 20 km. Their textures vary from coarse to porphyroclastic and mosaic-porphyroclastic up to cataclastic. Data have been collected by processing digital images acquired optically from standard petrographic thin sections. The acquisition method is based on a high-resolution colour scanner that allows image capturing of a whole thin section. Image processing was performed using the VISILOG 5.2 package, resolving crystals larger than about 150 μm and applying stereological corrections based on the Schwartz-Saltykov algorithm. Taking account of truncation effects due to resolution limits and thin section size, all samples show scale invariance of crystal size distributions over almost three orders of magnitude (0.2-25 mm). Power law relations show fractal dimensions varying between 2.4 and 3.8, a range of values observed for distributions of fragment sizes in a variety of other geological contexts. A fragmentation model can reproduce the fractal dimensions around 2.6, which correspond to well-equilibrated granoblastic textures. Fractal dimensions >3 are typical of porphyroclastic and cataclastic samples. Slight bends in some linear arrays suggest selective tectonic crushing of crystals with size larger than 1 mm. The scale invariance shown by lithospheric mantle xenoliths in a variety of tectonic settings forms distant geographic regions, which indicate that this is a common characteristic of the upper mantle and should be taken into account in rheological models and evaluation of metasomatic models.
2011-01-24
... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Central Minnesota Municipal Power Agency, Midwest Municipal Transmission... Municipal Power Agency and Midwest Municipal Transmission Group submitted an amendment to a petition for...
Relations between high and low power groups: the importance of legitimacy.
Hornsey, Matthew J; Spears, Russell; Cremers, Iris; Hogg, Michael A
2003-02-01
Using a social identity perspective, two experiments examined the effects of power and the legitimacy of power differentials on intergroup bias. In Experiment 1, 125 math-science students were led to believe that they had high or low representation in a university decision-making body relative to social-science students and that this power position was either legitimate or illegitimate. Power did not have an independent effect on bias; rather, members of both high and low power groups showed more bias when the power hierarchy was illegitimate than when it was legitimate. This effect was replicated in Experiment 2 (N = 105). In addition, Experiment 2 showed that groups located within an unfair power hierarchy expected the superordinate power body to be more discriminatory than did those who had legitimately high or low power. The results are discussed in terms of their implications for group relations.
Non abelian tensor square of non abelian prime power groups
2010-01-01
For every $p$-group of order $p^n$ with the derived subgroup of order $p^m$, Rocco in \\cite{roc} has shown that the order of tensor square of $G$ is at most $p^{n(n-m)}$. In the present paper not only we improve his bound for non-abelian $p$-groups but also we describe the structure of all non-abelian $p$-groups when the bound is attained for a special case. Moreover, our results give as well an upper bound for the order of $\\pi_3(SK(G, 1))$.
When sparks fly harnessing the power of group creativity
Leonard, Dorothy
2005-01-01
Creativity and innovation are evergreen topics. Particularly in today's tough marketplace, companies in every industry are looking for ways to harness creativity and innovation to spur growth and enhance competitiveness. This book differs from many books on creativity in that its focus is on how to manage a group, rather than individual creativity. It refutes much conventional wisdom about where creativity comes from, particularly that creativity does not stem from the random genius of individuals. The authors reveal specific group configurations and strategies that can unleash the collective creativity of any team or group.
Chakraborty, Sudipta; Kramer, William E
2013-01-01
While most books approach power electronics and renewable energy as two separate subjects, Power Electronics for Renewable and Distributed Energy Systems takes an integrative approach; discussing power electronic converters topologies, controls and integration that are specific to the renewable and distributed energy system applications. An overview of power electronic technologies is followed by the introduction of various renewable and distributed energy resources that includes photovoltaics, wind, small hydroelectric, fuel cells, microturbines and variable speed generation. Energy storage s
DEFF Research Database (Denmark)
Hu, Weihao; Chen, Zhe; Bak-Jensen, Birgitte;
2014-01-01
power loss minimization in distribution systems. In this paper, a new method to achieve power loss minimization in distribution systems by using a price signal to guide the demand side management is proposed. A fuzzy adaptive particle swarm optimization (FAPSO) is used as a tool for the power loss...... minimization study. Simulation results show that the proposed approach is an effective measure to achieve power loss minimization in distribution systems....
Lian Malai Madsen
2004-01-01
The study concerns the linguistic power wielding in group conversations among bilingual children and adolescents. In bilingual conversations one of the pragmatic linguistic means of negotiating power relations and identities is of course the choice of language. This is also the main subject of the study of Jørgensen (1993) who presents a view on the linguistic power wielding in group conversation in which he combines code-switching theories with Kjøller’s (1991) concepts of linguistic power w...
ABO and Rh Blood Groups Distribution in Yozgat City, Turkey
Directory of Open Access Journals (Sweden)
Çiğdem Kader
2014-06-01
Full Text Available Objective: In this retrospective study, we included 5257 healthy participants who admitted to Yozgat Government Hospital Blood Bank and Bozok University Blood Bank for several reasons to determine A, B, 0, AB blood groups and Rhesus (Rh positivity ratios between January 2007 and April 2013. Methods: We recorded their blood group types, age and gender from the hospital data. 2430 females, 2827 males totally 5257 participants were included to our study. Results: 2330 (44.3% persons were A blood group, 837 (15.9% were B group, 1665 (31.7% were 0 and 425 (%8.1 were AB group. Rh positivity ratio of our study group was 88%. Blood group frequency of Yozgat city is similar to other cities and the general population of our country, Turkey. Conclusion: Knowing the blood group is important for the blood recruitment in our region. J Clin Exp Invest 2014; 5 (2: 169-172
The power of talk: developing discriminatory group norms through discussion.
Smith, Laura G E; Postmes, Tom
2011-06-01
Research has shown that group discussion can increase intergroup prejudice and discrimination. However, we know little about the process by which discussion has this effect. Therefore, four studies were conducted in a real-world context to investigate this process. Results suggest that discussing a negative societal stereotype (relative to individual rumination in Studies 1 and 3 and alternative discussions in Studies 2 and 3) increases intentions to engage in discrimination against the out-group target of the stereotype. This is mediated by the formation of an in-group norm which supports discrimination (Study 1) and the extent to which the discussion validates the stereotype (Study 2). A fourth study manipulated the extent to which consensus on the negative stereotype was reached through discussion. When the discussion ended in consensus, participants have greater intention to undertake collective action against the stereotyped out-group, mediated by a congruent in-group norm. These results provide evidence that the process by which discussion increases intergroup discrimination is via the formation of discriminatory local group norms. ©2010 The British Psychological Society.
2012-08-23
... Employment and Training Administration Dana Holding Corporation, Power Technologies Group Division, Including... Holding Corporation, Power Technologies Group Division, Milwaukee, Wisconsin (subject firm). The negative... competitive articles) in 2011 and 2012, loss of business with a firm that employed a worker group eligible...
Optimum Distribution Generator Placement in Power Distribution System Using Ant Colony Algorithm
Directory of Open Access Journals (Sweden)
Mehdi Mahdavi
2009-03-01
Full Text Available The recent development in renewable energy systems and the high demand for having clean and low cost energy sources encourage people to use distributed generator (DG systems. Proper addition and placement of DG units can increase reliability and reduce the loss and production cost. In this paper using Ant Colony method, we developed an optimum placing scheme for DGs. The proposed method is tested on an IEEE 34-shinhe system. Results show that if DGs are able to generate active power, their effectiveness will increase.
Overvoltages related to distributed generation-power system interconnection transformer
Energy Technology Data Exchange (ETDEWEB)
Zamanillo, G.R.; Gomez, J.C.; Florena, E.F. [Rio Cuarto National University (IPSEP/UNRC), Cordoba (Argentina). Electric Power Systems Protection Institute], Email: jcgomez@ing.unrc.edu.ar
2009-07-01
The energy crisis that experiences the world drives to carry to an extreme, the use of all energy sources which are available. The sources need to be connected to the electric network in their next point, requiring of electric-electronic interfaces. The traditional electric power systems are changing their characteristics, in what concerns to structure, operation and on overvoltage generation. This change is not taking place in coordinated form among the involved sectors. The interconnection of a Distributed Generator (DG) directly with the power system is objectionable and risky. It is required of an interconnection transformer which performs several functions. Rigid specifications do not exist in this respect, for the variety of systems in use in the world, nevertheless there are utilities recommendations. Overvoltages caused by the DG, which arise due to the change of structure of the electric system, are explained. The transformer connection selection, presents positive and negative aspects that impact the utility and the user in a different or many times in an antagonistic way. The phenomenon of balanced and unbalanced ferroresonance overvoltage is studied. This phenomenon can takes place when using DG, either with synchronous or asynchronous generator, and for any type of connection of the transformer. The necessary conditions so that the phenomenon appears are presented. Eight interconnection transformer connection ways were studied. It is concluded that the solutions to reach by means of the employment of the DG, offer technical-economic advantages so much to the utility as to the user. It is also concluded in this work that the more advisable interconnection type is function of the system connection type. (author)
Directory of Open Access Journals (Sweden)
Abouzar Samimi
2016-01-01
Full Text Available One of the most significant control schemes in optimal operation of distribution networks is Volt/Var control (VVC. Owing to the radial structure of distribution systems and distribution lines with a small X/R ratio, the active power scheduling affects the VVC issue. A Distribution System Operator (DSO procures its active and reactive power requirements from Distributed Generations (DGs along with the wholesale electricity market. This paper proposes a new operational scheduling method based on a joint day-ahead active/reactive power market at the distribution level. To this end, based on the capability curve, a generic reactive power cost model for DGs is developed. The joint active/reactive power dispatch model presented in this paper motivates DGs to actively participate not only in the energy markets, but also in the VVC scheme through a competitive market. The proposed method which will be performed in an offline manner aims to optimally determine (i the scheduled active and reactive power values of generation units; (ii reactive power values of switched capacitor banks; and (iii tap positions of transformers for the next day. The joint active/reactive power dispatch model for daily VVC is modeled in GAMS and solved with the DICOPT solver. Finally, the plausibility of the proposed scheduling framework is examined on a typical 22-bus distribution test network over a 24-h period.
The place of solar power: an economic analysis of concentrated and distributed solar power
Directory of Open Access Journals (Sweden)
Banoni Vanessa
2012-04-01
Full Text Available Abstract Background This paper examines the cost and benefits, both financial and environmental, of two leading forms of solar power generation, grid-tied photovoltaic cells and Dish Stirling Systems, using conventional carbon-based fuel as a benchmark. Methods First we define how these solar technologies will be implemented and why. Then we delineate a model city and its characteristics, which will be used to test the two methods of solar-powered electric distribution. Then we set the constraining assumptions for each technology, which serve as parameters for our calculations. Finally, we calculate the present value of the total cost of conventional energy needed to power our model city and use this as a benchmark when analyzing both solar models’ benefits and costs. Results The preeminent form of distributed electricity generation, grid-tied photovoltaic cells under net-metering, allow individual homeowners a degree of electric self-sufficiency while often turning a profit. However, substantial subsidies are required to make the investment sensible. Meanwhile, large dish Stirling engine installations have a significantly higher potential rate of return, but face a number of pragmatic limitations. Conclusions This paper concludes that both technologies are a sensible investment for consumers, but given that the dish Stirling consumer receives 6.37 dollars per watt while the home photovoltaic system consumer receives between 0.9 and 1.70 dollars per watt, the former appears to be a superior option. Despite the large investment, this paper deduces that it is far more feasible to get few strong investors to develop a solar farm of this magnitude, than to get 150,000 households to install photovoltaic arrays in their roofs. Potential implications of the solar farm construction include an environmental impact given the size of land require for this endeavour. However, the positive aspects, which include a large CO2 emission reduction aggregated
The place of solar power: an economic analysis of concentrated and distributed solar power
2012-01-01
Background This paper examines the cost and benefits, both financial and environmental, of two leading forms of solar power generation, grid-tied photovoltaic cells and Dish Stirling Systems, using conventional carbon-based fuel as a benchmark. Methods First we define how these solar technologies will be implemented and why. Then we delineate a model city and its characteristics, which will be used to test the two methods of solar-powered electric distribution. Then we set the constraining assumptions for each technology, which serve as parameters for our calculations. Finally, we calculate the present value of the total cost of conventional energy needed to power our model city and use this as a benchmark when analyzing both solar models’ benefits and costs. Results The preeminent form of distributed electricity generation, grid-tied photovoltaic cells under net-metering, allow individual homeowners a degree of electric self-sufficiency while often turning a profit. However, substantial subsidies are required to make the investment sensible. Meanwhile, large dish Stirling engine installations have a significantly higher potential rate of return, but face a number of pragmatic limitations. Conclusions This paper concludes that both technologies are a sensible investment for consumers, but given that the dish Stirling consumer receives 6.37 dollars per watt while the home photovoltaic system consumer receives between 0.9 and 1.70 dollars per watt, the former appears to be a superior option. Despite the large investment, this paper deduces that it is far more feasible to get few strong investors to develop a solar farm of this magnitude, than to get 150,000 households to install photovoltaic arrays in their roofs. Potential implications of the solar farm construction include an environmental impact given the size of land require for this endeavour. However, the positive aspects, which include a large CO2 emission reduction aggregated over the lifespan of the farm
Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation
Energy Technology Data Exchange (ETDEWEB)
Nguyen Minh
2005-12-01
This report summarizes the work performed by Hybrid Power Generation Systems, LLC (HPGS) under Cooperative Agreement DE-FC2601NT40779 for the US Department of Energy, National Energy Technology Laboratory (DoE/NETL) entitled ''Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation''. The main objective of this project is to develop and demonstrate the feasibility of a highly efficient hybrid system integrating a planar Solid Oxide Fuel Cell (SOFC) and a gas turbine. A conceptual hybrid system design was selected for analysis and evaluation. The selected system is estimated to have over 65% system efficiency, a first cost of approximately $650/kW, and a cost of electricity of 8.4 cents/kW-hr. A control strategy and conceptual control design have been developed for the system. A number of SOFC module tests have been completed to evaluate the pressure impact to performance stability. The results show that the operating pressure accelerates the performance degradation. Several experiments were conducted to explore the effects of pressure on carbon formation. Experimental observations on a functioning cell have verified that carbon deposition does not occur in the cell at steam-to-carbon ratios lower than the steady-state design point for hybrid systems. Heat exchanger design, fabrication and performance testing as well as oxidation testing to support heat exchanger life analysis were also conducted. Performance tests of the prototype heat exchanger yielded heat transfer and pressure drop characteristics consistent with the heat exchanger specification. Multicell stacks have been tested and performance maps were obtained under hybrid operating conditions. Successful and repeatable fabrication of large (>12-inch diameter) planar SOFC cells was demonstrated using the tape calendering process. A number of large area cells and stacks were successfully performance tested at ambient and pressurized conditions. A 25 MW plant configuration was
The power of talk : Developing discriminatory group norms through discussion
Smith, Laura G. E.; Postmes, Tom
Research has shown that group discussion can increase intergroup prejudice and discrimination. However, we know little about the process by which discussion has this effect. Therefore, four studies were conducted in a real-world context to investigate this process. Results suggest that discussing a
Beyond Idea Generation: The Power of Groups in Developing Ideas
McMahon, Kibby; Ruggeri, Azzurra; Kämmer, Juliane E.; Katsikopoulos, Konstantinos V.
2016-01-01
Brainstorming research has claimed that individuals are more creative than groups. However, these conclusions are largely based on measuring creativity by the number of ideas generated, and researchers have tended to neglect other important components of creativity, such as the quality of developed ideas. These studies aim to address this gap in…
The power of talk : Developing discriminatory group norms through discussion
Smith, Laura G. E.; Postmes, Tom
2011-01-01
Research has shown that group discussion can increase intergroup prejudice and discrimination. However, we know little about the process by which discussion has this effect. Therefore, four studies were conducted in a real-world context to investigate this process. Results suggest that discussing a
Beyond Idea Generation: The Power of Groups in Developing Ideas
McMahon, Kibby; Ruggeri, Azzurra; Kämmer, Juliane E.; Katsikopoulos, Konstantinos V.
2016-01-01
Brainstorming research has claimed that individuals are more creative than groups. However, these conclusions are largely based on measuring creativity by the number of ideas generated, and researchers have tended to neglect other important components of creativity, such as the quality of developed ideas. These studies aim to address this gap in…
A Secure Session Key Distribution Scheme for Group Communications
Institute of Scientific and Technical Information of China (English)
LIN Ren-hung; JAN Jinn-ke
2006-01-01
In a secure group communication system, messages must be encrypted before being transmitted to group members to prevent unauthorized access. In many secure group communication schemes, whenever a member leaves or joins the group, group center (GC) immediately changes the common encryption key and sends the new key to all valid members for forward and backward secrecy. If valid members are not on-line, they will miss the rekeying messages and will not be able to decrypt any ciphertext. Therefore, group members must be able to store the state of the system. In some applications, like global positioning systems (GPS) or pay-per-view systems, it is not reasonable to ask group members to stay on-line all the time and save the changes to the system. A hierarchical binary tree-based key management scheme are proposed for a secure group communication. This scheme reduces the key storage requirement of GC to a constant size and the group members are not required to be on-line constantly (stateless).
Space vehicle electrical power processing distribution and control study. Volume 1: Summary
Krausz, A.
1972-01-01
A concept for the processing, distribution, and control of electric power for manned space vehicles and future aircraft is presented. Emphasis is placed on the requirements of the space station and space shuttle configurations. The systems involved are referred to as the processing distribution and control system (PDCS), electrical power system (EPS), and electric power generation system (EPGS).
Impacts of Electric Vehicle Loads on Power Distribution Systems
DEFF Research Database (Denmark)
Pillai, Jayakrishnan Radhakrishna; Bak-Jensen, Birgitte
2010-01-01
Electric vehicles (EVs) are the most promising alternative to replace a significant amount of gasoline vehicles to provide cleaner, CO2 free and climate friendly transportation. On integrating more electric vehicles, the electric utilities must analyse the related impacts on the electricity syste...... be accommodated in the network with the smart charging mode. The extent of integrating EVs in an area is constrained by the EV charging behavior and the safe operational limits of electricity system parameters....... operation. This paper investigates the effects on the key power distribution system parameters like voltages, line drops, system losses etc. by integrating electric vehicles in the range of 0-50% of the cars with different charging capacities. The dump as well as smart charging modes of electric vehicles......Electric vehicles (EVs) are the most promising alternative to replace a significant amount of gasoline vehicles to provide cleaner, CO2 free and climate friendly transportation. On integrating more electric vehicles, the electric utilities must analyse the related impacts on the electricity system...
The distribution of absorptive power dissipation in irradiated nanoparticulate system
Li, Jiayu; Yang, Jian; Gu, Xiaobing
2016-10-01
The knowledge of local radiant absorption is important to the nanostructure optimization, it is beneficial to the applications in energy harvesting, optical heating, photocatalysis, etc. In this paper, FDTD model is constructed for the distribution of absorptive power dissipation in irradiated nanoparticulate system. The theoretical model extended from Mie theory is used to examine the FDTD model, the parameters and conditions set for FDTD simulation are confirmed based on the comparison. Then, the influence of Ag nanoparticle on the absorptive properties of nearby TiO2 nanoparticle is investigated by FDTD simulation at the wavelength of 0.25 μm. It is indicated that suitable distance between TiO2 and Ag particles is beneficial to the spectral radiant absorption of TiO2 particle. Considering the agglomeration of nanoparticles and the oxidation at the TiO2-Ag interface, the Ag core coated with Al2O3 shell is suggested, and the simulated results indicated that the shell thickness and the Ag core size need to be optimized for enhancing the radiant absorption of TiO2 particle.
Review of modular power converters solutions for smart transformer in distribution system
DEFF Research Database (Denmark)
Alzola, Rafael Pena; Gohil, Ghanshyamsinh Vijaysinh; Mathe, Laszlo
2013-01-01
While the use of power electronics based Smart Transformer (ST) is becoming a reality in traction applications, and it has been considered as an interesting option for interfacing different transmission systems, the possibility to use it in distribution systems is still considered futuristic....... Replacing primary distribution transformers with ST can lead to more flexible handling of the distribution feeders, while replacing secondary distribution transformers can allow decoupling of distribution network. This paper reviews different power converter solutions for the ST focusing on modularity...
Aboriginal groups taking leadership positions in power sector
Energy Technology Data Exchange (ETDEWEB)
Kishewitsch, S.
2009-09-15
First Nations and Metis communities are now initiating and managing projects in the Canadian energy sector. Federal and provincial governments are now developing training programs to ensure that Aboriginal communities develop the skills needed to successfully manage energy projects. The Supreme Court of Canada has issued a number of rulings ensuring that companies and government agencies have a duty to consult with Aboriginal people when Crown decisions impact Treaty or Aboriginal rights. The Ministry of Energy and Infrastructure has now set up a unit to provide advice and guidance to facilitate partnership opportunities with First Nations and Metis communities. Major companies in Ontario have also developed consultation policies that focus on relationship building, internal education, and promoting business and workforce development. The Pic River First Nation group now owns a minority interest in the Wawatay generating station. A 23 MW facility is fully owned by the First Nations group. The province of Ontario has made a provision for up to $250 million to serve as loan guarantees for First Nations groups. It was concluded that the Electricity Sector Council (ESC) has developed an Aboriginal participation engagement project designed to increase Aboriginal awareness of opportunities within the electricity and renewable energy sector. 3 figs.
Distributed solid state programmable thermostat/power controller
Alexander, Jane C. (Inventor); Howard, David E. (Inventor); Smith, Dennis A. (Inventor)
2008-01-01
A self-contained power controller having a power driver switch, programmable controller, communication port, and environmental parameter measuring device coupled to a controllable device. The self-contained power controller needs only a single voltage source to power discrete devices, analog devices, and the controlled device. The programmable controller has a run mode which, when selected, upon the occurrence of a trigger event changes the state of a power driver switch and wherein the power driver switch is maintained by the programmable controller at the same state until the occurrence of a second event.
A Possible Origin of Power-Law Distribution in Stock Markets
Institute of Scientific and Technical Information of China (English)
杨纯斌; 蔡勖
2002-01-01
The origin of the power-law distribution in stock markets is discussed from the point of view of self-organized criticality. An analytical expression for the distribution is given from a simple model consideration. We see that power-law increasing or decreasing distribution functions can have the same origin, depending on the values of the parameters.
Scholl, Annika; Sassenrath, Claudia; Sassenberg, Kai
2015-01-01
Depending on their motivation, individuals prefer different group contexts for social interactions. The present research sought to provide more insight into this relationship. More specifically, we tested how challenge/threat and a promotion/prevention focus predict attraction to groups with high- or low-power. As such, we examined differential outcomes of threat and prevention focus as well as challenge and promotion focus that have often been regarded as closely related. According to regulatory focus, individuals should prefer groups that they expect to "feel right" for them to join: Low-power groups should be more attractive in a prevention (than a promotion) focus, as these groups suggest security-oriented strategies, which fit a prevention focus. High-power groups should be more attractive in a promotion (rather than a prevention) focus, as these groups are associated with promotion strategies fitting a promotion focus (Sassenberg et al., 2007). In contrast, under threat (vs. challenge), groups that allow individuals to restore their (perceived) lack of control should be preferred: Low-power groups should be less attractive under threat (than challenge) because they provide low resources which threatened individuals already perceive as insufficient and high-power groups might be more attractive under threat (than under challenge), because their high resources allow individuals to restore control. Two experiments (N = 140) supported these predictions. The attractiveness of a group often depends on the motivation to engage in what fits (i.e., prefer a group that feels right in the light of one's regulatory focus). However, under threat the striving to restore control (i.e., prefer a group allowing them to change the status quo under threat vs. challenge) overrides the fit effect, which may in turn guide individuals' behavior in social interactions.
DEFF Research Database (Denmark)
Wu, Hongfei; Sun, Kai; Chen, Min
2013-01-01
the proposed system, which benefits for implementing high MPPT efficiency and high conversion efficiency simultaneously. A hybrid MPPT control strategy is proposed for this HCD power conditioning system. The characteristics, circuit implementation and operation principles of the proposed system are presented......-distributed (HCD) power conditioning system for TEG and its control strategy are proposed in this paper. The HCD power conditioning system is composed by a centralized power conversion stage and multiple distributed power conversion stages. Most of the power is processed by the centralized power conversion stage...
On the power graphs which are Cayley graphs of some groups
Mukherjee, S.; Bhuniya, A. K.
2015-01-01
In 2013, Jemal Abawajy, Andrei Kelarev and Morshed Chowdhury [1] proposed a problem to characterize the finite groups whose power graphs are Cayley graphs of some groups. Here we give a complete answer to this question.
Kubo, Takuro; Furukawa, Tatsuya; Itoh, Hideaki; Fukumoto, Hisao; Wakuya, Hiroshi; Ohchi, Masashi
We have proposed and preproducted the voltage-current waveform sensor of resin molded type for measuring the power factor and harmonics in power distribution systems. We have executed numerical electromagnetic analyses using the finite element method to estimate the characteristics and behaviours of the sensor. Although the magnetic field analyses for the current sensor have involved the measurement circuit, the electric field analyses have not included the measurement circuit for measuring voltage waveforms of power lines. In this paper, we describe the electric field analyses with the measurement circuit and prove the insulating strength of the proposed sensor permissible to the use in 22kV power distribution systems.
Comparing Amino Acid Abundances and Distributions Across Carbonaceous Chondrite Groups
Burton, Aaron S.; Callahan, Michael P.; Glavin, Daniel P.; Elsila, Jamie E.; Dworkin, Jason P.
2012-01-01
Meteorites are grouped according to bulk properties such as chemical composition and mineralogy. These parameters can vary significantly among the different carbonaceous chondrite groups (CI, CM, CO, CR, CH, CB, CV and CK). We have determined the amino acid abundances of more than 30 primary amino acids in meteorites from each of the eight groups, revealing several interesting trends. There are noticeable differences in the structural diversity and overall abundances of amino acids between meteorites from the different chondrite groups. Because meteorites may have been an important source of amino acids to the prebiotic Earth and these organic compounds are essential for life as we know it, the observed variations of these molecules may have been important for the origins of life.
Zhang, Jiang; Zhou, Jiansong; Lu, Fengmei; Chen, Liangyin; Huang, Yunzhi; Chen, Huafu; Xiang, Yutao; Yang, Gang; Yuan, Zhen
2017-07-17
Conduct disorder (CD) is a psychiatric disorder in children and adolescence. To investigate changes in the power distribution in brain networks between CD and typically developing (TD) groups, resting-state functional magnetic resonance imaging (rsfMRI) data of thirty-six subjects were first recorded, and then the data were preprocessed using DPARSF and SPM8. Meanwhile, the power of the blood oxygenation level-dependent (BOLD) signals of ninety brain regions was acquired using the integral of the Welch power spectral density (PSD). Additionally, the powers of the brain regions that reached significance (p brain regions between the CD and TD groups, indicating a change in the power distribution. In addition, the results also suggest that the total power consumption of brain networks in CD patients is less than that observed in the TD group. Consequently, the study provided a paradigm for establishing quantifiable indicators via the power spectrum approach for the comparison and analysis of the BOLD signal power between CD patients and healthy controls.
Distributed Low-Complexity Controller for Wind Power Plant in Derated Operation
DEFF Research Database (Denmark)
Biegel, Benjamin; Madjidian, Daria; Spudic, Vedrana;
2013-01-01
We consider a wind power plant of megawatt wind turbines operating in derated mode. When operating in this mode, the wind power plant controller is free to distribute power set-points to the individual turbines, as long as the total power demand is met. In this work, we design a controller...
Distributed orientation agreement in a group of robots
Navarro Oiza, Iñaki; Matía Espada, Fernando
2012-01-01
In this article, a method for the agreement of a set of robots on a common reference orientation based on a distributed consensus algorithm is described. It only needs that robots detect the relative positions of their neighbors and communicate with them. Two different consensus algorithms based on the exchange of information are proposed, tested and analyzed. Systematic experiments were carried out in simulation and with real robots in order to test the method. Experimental results show that...
The influence of bromazepam on cortical power distribution
Directory of Open Access Journals (Sweden)
Isabel Sampaio
2008-06-01
Full Text Available The EEG has been widely employed in the assessment of electrophysiological changes induced by distinct medications. Its sensibility in detecting alterations produced by a specific substance may be enhanced by methods of quantitative analyses (qEEG. The present study aimed at investigating the modulatory effects of bromazepam on brain dynamics. The effects of bromazepam (3mg on EEG power distribution were tested in 10 healthy individuals, in a double-blind experiment. The electrophysiological measure was analyzed across experimental conditions, moments, and electrodes, in the delta, theta, alpha and beta frequency bands separately. A significant decrease of relative power was observed in delta and theta (main effect of condition. No interactions were observed. Although the expected anxiolytic EEG profile was not observed (increased beta and decreased alpha activity, this specific result may be related to other factors such as dosage used and the subjects' general physiological state, and not necessarily to the drug itself.O EEG tem sido amplamente empregado na avaliação de mudanças eletrofisiológicas induzidas por medicações distintas.A sensibilidade desta técnica em detectar alterações produzidas por uma substância pode ser aprimorada por métodos de análise quantitativa (EEGq. O presente estudo teve por objetivo investigar os efeitos modulatórios do bromazepam na dinâmica cerebral. Os efeitos de 3mg de bromazepam na distribuição de potência cortical foram observados em 10 indivíduos sadios, em um desenho duplo-cego. A medida eletrofisiológica foi analisada nas diferentes condições experimentais, momentos e eletrodos, em delta, teta, alfa e beta separadamente. Uma diminuição significativa de potência relativa foi observada em delta e teta (efeito principal para condição. Não foram observadas interações. Embora o perfil ansiolítico do EEG (aumento de beta e diminuição de alfa não tenha sido observado, esteresultado
A Review of Distributed Control Techniques for Power Quality Improvement in Micro-grids
Zeeshan, Hafiz Muhammad Ali; Nisar, Fatima; Hassan, Ahmad
2017-05-01
Micro-grid is typically visualized as a small scale local power supply network dependent on distributed energy resources (DERs) that can operate simultaneously with grid as well as in standalone manner. The distributed generator of a micro-grid system is usually a converter-inverter type topology acting as a non-linear load, and injecting harmonics into the distribution feeder. Hence, the negative effects on power quality by the usage of distributed generation sources and components are clearly witnessed. In this paper, a review of distributed control approaches for power quality improvement is presented which encompasses harmonic compensation, loss mitigation and optimum power sharing in multi-source-load distributed power network. The decentralized subsystems for harmonic compensation and active-reactive power sharing accuracy have been analysed in detail. Results have been validated to be consistent with IEEE standards.
The Role of Distributed Generation and Combined Heat and Power (CHP) Systems in Data Centers
This report reviews how distributed generation (DG) resources such as fuel cells, reciprocating engines, and gas turbines can offer powerful energy efficiency savings in data centers, particularly when configured in combined heat and power (CHP) mode.
Distributed AC power flow method for AC and AC-DC hybrid ...
African Journals Online (AJOL)
DR OKE
Hence the distribution power flow models to be developed were supposed to include both mesh and DG modeling (Sedghi ... Newton-Raphson based power flow methods, namely Newton ... Equation (1) is the mathematical realization of this ...
Power-supply-operations group-training programs, ac/dc power systems and micellaneous information
Energy Technology Data Exchange (ETDEWEB)
Harris, C A
1978-06-30
This program introduces the technician to three phase a-c power and its relationship to rectifier power conversion systems. A brief introduction is given as to the engineering significance of various parameters such as, phase rotation, ac power relationships, harmonics, transformer voltage vectors, rectifier parameters, filters, water cooling, phase delayed triggers to SCR's, dielectric stress vs life and other related subjects. The significance of the details as they apply to various diagnostic problems that a technician may be called upon to solve is emphasized. Reference CAPE-2747.
Directory of Open Access Journals (Sweden)
Rongxiang Yuan
2016-04-01
Full Text Available In the traditional paradigm, large power plants provide active and reactive power required for the transmission system and the distribution network purchases grid power from it. However, with more and more distributed energy resources (DERs connected at distribution levels, it is necessary to schedule DERs to meet their demand and participate in the electricity markets at the distribution level in the near future. This paper proposes a comprehensive operational scheduling model to be used in the distribution management system (DMS. The model aims to determine optimal decisions on active elements of the network, distributed generations (DGs, and responsive loads (RLs, seeking to minimize the day-ahead composite economic cost of the distribution network. For more detailed simulation, the composite cost includes the aspects of the operation cost, emission cost, and transmission loss cost of the network. Additionally, the DMS effectively utilizes the reactive power support capabilities of wind and solar power integrated in the distribution, which is usually neglected in previous works. The optimization procedure is formulated as a nonlinear combinatorial problem and solved with a modified differential evolution algorithm. A modified 33-bus distribution network is employed to validate the satisfactory performance of the proposed methodology.
Power distribution in complex environmental negotiations: Does balance matter?
Burkardt, N.; Lamb, B.L.; Taylor, J.G.
1997-01-01
We studied six interagency negotiations covering Federal Energy Regulatory Commission (FERC) hydroelectric power licenses. Negotiations occurred between state and federal resource agencies and developers over project operations and natural resource mitigation. We postulated that a balance of power among parties was necessary for successful negotiations. We found a complex relationship between balanced power and success and conclude that a balance of power was associated with success in these negotiations. Power played a dynamic role in the bargaining and illuminates important considerations for regulatory design.
2010-02-08
... Federal Energy Regulatory Commission Central Minnesota Municipal Power Agency and Midwest Municipal Transmission Group, Inc.; Notice of Filing February 1, 2010. Take notice that on January 25, 2010, Central Minnesota Municipal Power Agency and Midwest Municipal Transmission Group, Inc. (CMMPA/ MMTG) filed with...
MARIUT, E. L.; HELEREA, E.
2016-01-01
This paper deals with the analysis of the effects of electromagnetic transients generated by lightning on power distribution lines, considering the influence of tower footing resistance variation. Both types of lightning stroke, direct and induced, are considered. The model of a 20 kV three-phase overhead power distribution line is performed considering a simple line circuit with triangle canopy and 50/8 mm2 Ol-Al conductors. The model of the power distribution line is done consid...
Directory of Open Access Journals (Sweden)
Dan Wang
2013-08-01
Full Text Available This paper presents research on the voltage and current distortion in the input stage, isolation stage and output stage of Distribution Electronic Power transformer (D-EPT after the open-circuit and short-circuit faults of its power switches. In this paper, the operational principles and the control methods for input stage, isolation stage and output stage of D-EPT, which work as a cascaded H-bridge rectifier, DC-DC converter and inverter, respectively, are introduced. Based on conclusions derived from the performance analysis of D-EPT after the faults, this paper comes up with the effects from its topology design and control scheme on the current and voltage distortion. According to the EPT fault characteristics, since the waveforms of relevant components heavily depend on the location of the faulty switch, it is very easy to locate the exact position of the faulty switch. Finally, the fault characteristics peculiar to D-EPT are analyzed, and further discussed with simulation on the Saber platform, as well as a fault location diagnosis algorithm.
Energy Technology Data Exchange (ETDEWEB)
Treanton, B.; Palomo, J.; Kroposki, B.; Thomas, H.
2006-10-01
The Advanced Power Electronics Interfaces for Distributed Energy Workshop, sponsored by the California Energy Commission Public Interest Energy Research program and organized by the National Renewable Energy Laboratory, was held Aug. 24, 2006, in Sacramento, Calif. The workshop provided a forum for industry stakeholders to share their knowledge and experience about technologies, manufacturing approaches, markets, and issues in power electronics for a range of distributed energy resources. It focused on the development of advanced power electronic interfaces for distributed energy applications and included discussions of modular power electronics, component manufacturing, and power electronic applications.
Directory of Open Access Journals (Sweden)
Shahrokh Shojaeian
2014-01-01
Full Text Available There are always some uncertainties in prediction and estimation of distribution systems loads. These uncertainties impose some undesirable impacts and deviations on power flow of the system which may cause reduction in accuracy of the results obtained by system analysis. Thus, probabilistic analysis of distribution system is very important. This paper proposes a probabilistic power flow technique by applying a normal probabilistic distribution in seven standard deviations on forward-backward algorithm. The losses and voltage of IEEE 33-bus test distribution network is investigated by our new algorithm and the results are compared with the conventional algorithm i.e., based on deterministic methods.
Use of FACTS for enhanced flexibility and efficiency in power transmission and distribution grids
Energy Technology Data Exchange (ETDEWEB)
Grunbaum, Rolf; Wahlberg, Conny; Sannino, Ambra
2010-09-15
The paper shows how the use of FACTS increases flexibility in power transmission and distribution, improving capacity of transmission corridors to integrate renewable power production. Examples included are 69 kV directly connected SVCs for grid stabilization in conjunction with a high degree of wind power penetration; series compensation to evacuate power from the largest wind power installation in USA; SVC to increase the reliability and reduce congestion over a heavily loaded power corridor; thyristor controlled series compensation to increase the dynamic stability and power transmission capability of a power inter-connector. Finally, some applications of Dynamic energy storage are highlighted.
Impact of dependencies in risk assessments of power distribution systems
Alvehag, Karin
2008-01-01
Society has become increasingly dependent on electricity, so power system reliability is of crucial importance. However, while underinvestment leads to an unacceptable number of power outages, overinvestment will result in costs that are too high for society. The challenge is to find a socioeconomically adequate level of risk. In this risk assessment, not only the probability of power outages, but also the severity of their consequences should be included. A risk assessment can be performe...
Transmission of specific groups of bacteria through water distribution system.
Grabińska-Łoniewska, Anna; Wardzyńska, Grazyna; Pajor, Elzbieta; Korsak, Dorota; Boryń, Krystyna
2007-01-01
Microbial contamination of a water distribution system was examined. The number and the taxonomy of non-pigmented and pigmented heterotrophic bacteria (HB), number of bacteria (Pseudomonas sp., Enterococcus sp., Campylobacter sp., Yersinia sp., representatives of the Enterobacteriaceae, coagulase-positive staphylococci, and C. pefringens) in the bulk water phase, biomass of zoogloeal aggregates of bacteria, fungi, algae, protozoa and rotifers (ZABFAPR) (separated from the above on 5 microm pore size filters) and in pipe sediments was determined. An increased number of HB occurred at the sampling sites situated as close as 4.2 km to the Water Treatment Plant (WTP), and was especially significant at 10.3 km. It was shown that the main reservoir of hygienically relevant bacteria did not occur in the water phase which is monitored in routine control analyses carried out by the WTP laboratories, but in the ZABFAPR biomass not monitored so far.
Distributed communication and psychosocial performance in simulated space dwelling groups
Hienz, R. D.; Brady, J. V.; Hursh, S. R.; Ragusa, L. C.; Rouse, C. O.; Gasior, E. D.
2005-05-01
The present report describes the development and application of a distributed interactive multi-person simulation in a computer-generated planetary environment as an experimental test bed for modeling the human performance effects of variations in the types of communication modes available, and in the types of stress and incentive conditions underlying the completion of mission goals. The results demonstrated a high degree of interchangeability between communication modes (audio, text) when one mode was not available. Additionally, the addition of time pressure stress to complete tasks resulted in a reduction in performance effectiveness, and these performance reductions were ameliorated via the introduction of positive incentives contingent upon improved performances. The results obtained confirmed that cooperative and productive psychosocial interactions can be maintained between individually isolated and dispersed members of simulated spaceflight crews communicating and problem-solving effectively over extended time intervals without the benefit of one another's physical presence.
de Busserolles, Fanny; Marshall, N Justin; Collin, Shaun P
2014-01-01
Topographic analyses of retinal ganglion cell density are very useful in providing information about the visual ecology of a species by identifying areas of acute vision within the visual field (i.e. areas of high cell density). In this study, we investigated the neural cell distribution in the ganglion cell layer of a range of lanternfish species belonging to 10 genera. Analyses were performed on wholemounted retinas using stereology. Topographic maps were constructed of the distribution of all neurons and both ganglion and amacrine cell populations in 5 different species from Nissl-stained retinas using cytological criteria. Amacrine cell distribution was also examined immunohistochemically in 2 of the 5 species using anti-parvalbumin antibody. The distributions of both the total neuron and the amacrine cell populations were aligned in all of the species examined, showing a general increase in cell density toward the retinal periphery. However, when the ganglion cell population was topographically isolated from the amacrine cell population, which comprised up to 80% of the total neurons within the ganglion cell layer, a different distribution was revealed. Topographic maps of the true ganglion cell distribution in 18 species of lanternfishes revealed well-defined specializations in different regions of the retina. Different species possessed distinct areas of high ganglion cell density with respect to both peak density and the location and/or shape of the specialized acute zone (i.e. elongated areae ventro-temporales, areae temporales and large areae centrales). The spatial resolving power was calculated to be relatively low (varying from 1.6 to 4.4 cycles per degree), indicating that myctophids may constitute one of the less visually acute groups of deep-sea teleosts. The diversity in retinal specializations and spatial resolving power within the family is assessed in terms of possible ecological functions and evolutionary history. © 2014 S. Karger AG, Basel.
De Busserolles, Fanny
2014-01-01
Topographic analyses of retinal ganglion cell density are very useful in providing information about the visual ecology of a species by identifying areas of acute vision within the visual field (i.e. areas of high cell density). In this study, we investigated the neural cell distribution in the ganglion cell layer of a range of lanternfish species belonging to 10 genera. Analyses were performed on wholemounted retinas using stereology. Topographic maps were constructed of the distribution of all neurons and both ganglion and amacrine cell populations in 5 different species from Nissl-stained retinas using cytological criteria. Amacrine cell distribution was also examined immunohistochemically in 2 of the 5 species using anti-parvalbumin antibody. The distributions of both the total neuron and the amacrine cell populations were aligned in all of the species examined, showing a general increase in cell density toward the retinal periphery. However, when the ganglion cell population was topographically isolated from the amacrine cell population, which comprised up to 80% of the total neurons within the ganglion cell layer, a different distribution was revealed. Topographic maps of the true ganglion cell distribution in 18 species of lanternfishes revealed well-defined specializations in different regions of the retina. Different species possessed distinct areas of high ganglion cell density with respect to both peak density and the location and/or shape of the specialized acute zone (i.e. elongated areae ventro-temporales, areae temporales and large areae centrales). The spatial resolving power was calculated to be relatively low (varying from 1.6 to 4.4 cycles per degree), indicating that myctophids may constitute one of the less visually acute groups of deep-sea teleosts. The diversity in retinal specializations and spatial resolving power within the family is assessed in terms of possible ecological functions and evolutionary history.
Transition state theory: a generalization to nonequilibrium systems with power-law distributions
Jiulin, Du
2011-01-01
Transition state theory (TST) is generalized for the nonequilibrium system with power-law distributions. The stochastic dynamics that gives rise to the power-law distributions for the reaction coordinate and momentum is modeled by the Langevin equations and corresponding Fokker-Planck equations. It is assumed that the system far away from equilibrium has not to relax to a thermal equilibrium state with Boltzmann-Gibbs distribution, but asymptotically approaches to a nonequilibrium stationary-state with power-law distributions. Thus, we obtain a generalization of TST rates to nonequilibrium systems with power-law distributions. Furthermore, we derive the generalized TST rate constants for one-dimension and n-dimension Hamiltonian systems away from equilibrium, and receive a generalized Arrhenius rate for the system with power-law distributions.
IP MULTICAST GROUP MANAGEMENT FOR BROADCAST LANS DISTRIBUTION
Institute of Scientific and Technical Information of China (English)
阿姆贾德
2001-01-01
Problems of the current IGMP mechanism were identified, such as unnecessary periodic probing of hosts and leave latency, which wastes bandwidth and cause more traffic and overhead. Alternative mechanism that preserve the IP multicast model but employ join/leave messages to track local group membership for broadcast LANs (shared medium LANs) was proposed in this paper. We describe the implementation requirements of the new mechanism and compare it to existing one, demonstrating that join/leave approach is uniformly superior for the environment of broadcast LANs.
Distributed Energy Resources, Power Quality and Reliability - Background
Energy Technology Data Exchange (ETDEWEB)
Schienbein, Lawrence A.; DeSteese, John G.
2002-01-31
Power quality [PQ] and power reliability [PR] gained importance in the industrialized world as the pace of installation of sensitive appliances and other electrical loads by utility customers accelerated, beginning in the mid 1980s. Utility-grid-connected customers rapidly discovered that this equipment was increasingly sensitive to various abnormalities in the electricity supply.
Power tails of index distributions in chinese stock market
Zhang, J. W.; Zhang, Y.; Kleinert, H.
2007-04-01
The power α of the Lévy tails of stock market fluctuations discovered in recent years are generally believed to be universal. We show that for the Chinese stock market this is not true, the powers depending strongly on anomalous daily index changes short before market closure, and weakly on the opening data.
optimal location of distributed generation on the nigerian power ...
African Journals Online (AJOL)
user
optimal sizing and placement of DG in the Nigerian power network for active power loss minimization. The effectiveness of ... high impact on the integration of DG plants in the network are the .... hydro resources and thermal. Figure 3: Nigeria ...
Directory of Open Access Journals (Sweden)
Adesina, L.M
2015-07-01
Full Text Available The solution to power flow is one of the most important problems in electrical power systems. Traditional methods have been previously used for power flow analysis, but with prevalent drawbacks such as abnormal operating solutions and divergences in heavy loads. This paper presents power flow analysis in a power system, by modelling a typical 33kV Distribution Network, and simulating using the NEPLAN software for power flow studies. Island Business Unit’s (IBU 33kV network of Eko Electricity Distribution Plc (EKEDP for a scenario day is taken as case study in the analysis. The most important parameters of power flow analysis is utilized to find the magnitude and phase angles of the voltages at each Busbar, as well as the real and reactive power flowing through each distribution line within the network under consideration.
Distribution of influenza vaccine to high-risk groups.
Ompad, Danielle C; Galea, Sandro; Vlahov, David
2006-01-01
Vaccine distribution programs have historically targeted individuals at high risk of complications due to influenza. Despite recommendations from the Advisory Committee on Immunization Practices, vaccination coverage among high-risk populations has been generally low. This review systematically summarizes the recent literature evaluating programs in different settings, from within medical settings to venue-based and community-based approaches, in an effort to identify successful program components. The published literature was identified by using the MEDLINE database from 1990 to 2006 covering studies that reported on interventions or programs aimed at vaccinating high-risk populations. The authors reviewed 56 studies. In the United States, the Healthy People 2010 goals included 90% vaccination coverage for adults aged > or = 65 years and 60% for high-risk adults aged 18-64 years. Only a handful of the studies reviewed managed to meet those goals. Interventions that increased vaccination coverage to Healthy People 2010 goals included advertising, provider and patient mailings, registry-based telephone calls, patient and staff education, standing orders coupled with standardized forms, targeting of syringe exchange customers, and visiting nurses. Few studies evaluated the impact of vaccination programs by race/ethnicity and socioeconomic status. Few studies targeted individuals outside of the health-care and social services sectors. Given the growing disparities in health and health-care access, understanding the way in which interventions can remedy disparities is crucial.
Metallicity Distribution Functions of Four Local Group dwarf galaxies
Ross, Teresa L; Saha, Abhijit; Anthony-Twarog, Barbara J
2015-01-01
We present stellar metallicities in Leo I, Leo II, IC 1613, and Phoenix dwarf galaxies derived from medium (F390M) and broad (F555W, F814W) band photometry using the Wide Field Camera 3 (WFC3) instrument aboard the Hubble Space Telescope. We measured metallicity distribution functions (MDFs) in two ways, 1) matching stars to isochrones in color-color diagrams, and 2) solving for the best linear combination of synthetic populations to match the observed color-color diagram. The synthetic technique reduces the effect of photometric scatter, and produces MDFs 30-50 % narrower than the MDFs produced from individually matched stars. We fit the synthetic and individual MDFs to analytical chemical evolution models (CEM) to quantify the enrichment and the effect of gas flows within the galaxies. Additionally, we measure stellar metallicity gradients in Leo I and II. For IC 1613 and Phoenix our data do not have the radial extent to confirm a metallicity gradient for either galaxy. We find the MDF of Leo I (dwarf spher...
Kim, Dae San; Kim, Ji Hyun
2011-01-01
In this paper, we construct two ternary linear codes associated with the symplectic groups Sp(2,q) and Sp(4,q). Here q is a power of three. Then we obtain recursive formulas for the power moments of Kloosterman sums with square arguments and for the even power moments of those in terms of the frequencies of weights in the codes. This is done via Pless power moment identity and by utilizing the explicit expressions of "Gauss sums" for the symplectic groups Sp(2n,q).
Energy Technology Data Exchange (ETDEWEB)
Rose, A.; Frias, O. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Mineral Economics
1993-06-01
The purpose of this report is to present the methodology and results of an analysis of income distribution impacts associated with changes in the Western Area Power Administration (WAPA) marketing program. The focus will be on the distribution of personal income across eleven brackets in each of nine sub-regions of the WAPA market area. Moreover, these results will be translated into an assessment of the number of people who stand to gain or lose as a result of the policies and the size of these income changes. Most economic impact analyses are performed at an aggregate level. The results are typically presented in terms of net benefits, or a listing of changes in employment, output, income, or prices. What is neglected is the distribution of impacts across the affected population. These distributional impacts are important for several reasons. First, there is the normative judgmental issue of distributional justice, or equity. This addresses concerns about income disparities in general, or whether the poor, or any other group, are shouldering a disproportionate share of any burden or are failing to share significantly in any gain.
Golassa, Lemu; Tsegaye, Arega; Erko, Berhanu; Mamo, Hassen
2017-07-26
Knowledge of the distribution of ABO-Rh(D) blood groups in a locality is vital for safe blood services. However, the distribution of these blood systems among Ethiopians in general is little explored. This study was, therefore, designed to determine the ABO-Rh(D) blood group distribution among patients attending Gambella hospital, southwestern Ethiopia. A cross-sectional study was conducted between November and December 2013 (N = 449). The patients were grouped into two broad categories. Those who originally moved from different parts of Ethiopia and currently residing in Gambella are named 'highlanders' (n = 211). The other group consisted of natives (Nilotics) to the locality (n = 238). ABO-Rh(D) blood groups were typed by agglutination, open-slide test method, using commercial antisera (Biotech laboratories Ltd, Ipswich, Suffolk, UK). Overall, majority of the participants (41.20%) had blood type 'O' followed by types 'A' (34.96%), 'B' (20.48%) and 'AB' (3.34%). However, blood type 'A' was the most frequent (44.07%) blood group among the 'highlanders' and 50.42% of Nilotic natives had type 'O'. The proportion of participants devoid of the Rh factor was 19.37%. While the ABO blood group distribution is similar to previous reports, the Rh(D) frequency is much higher than what was reported so far for Ethiopia and continental Africa.
METALLICITY DISTRIBUTION FUNCTIONS OF FOUR LOCAL GROUP DWARF GALAXIES
Energy Technology Data Exchange (ETDEWEB)
Ross, Teresa L.; Holtzman, Jon [Department of Astronomy, New Mexico State University, P.O. Box 30001, MSC 4500, Las Cruces, NM 88003-8001 (United States); Saha, Abhijit [NOAO, 950 Cherry Avenue, Tucson, AZ 85726-6732 (United States); Anthony-Twarog, Barbara J., E-mail: rosst@nmsu.edu, E-mail: holtz@nmsu.edu, E-mail: bjat@ku.edu [Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045-7582 (United States)
2015-06-15
We present stellar metallicities in Leo I, Leo II, IC 1613, and Phoenix dwarf galaxies derived from medium (F390M) and broad (F555W, F814W) band photometry using the Wide Field Camera 3 instrument on board the Hubble Space Telescope. We measured metallicity distribution functions (MDFs) in two ways, (1) matching stars to isochrones in color–color diagrams and (2) solving for the best linear combination of synthetic populations to match the observed color–color diagram. The synthetic technique reduces the effect of photometric scatter and produces MDFs 30%–50% narrower than the MDFs produced from individually matched stars. We fit the synthetic and individual MDFs to analytical chemical evolution models (CEMs) to quantify the enrichment and the effect of gas flows within the galaxies. Additionally, we measure stellar metallicity gradients in Leo I and II. For IC 1613 and Phoenix our data do not have the radial extent to confirm a metallicity gradient for either galaxy. We find the MDF of Leo I (dwarf spheroidal) to be very peaked with a steep metal-rich cutoff and an extended metal-poor tail, while Leo II (dwarf spheroidal), Phoenix (dwarf transition), and IC 1613 (dwarf irregular) have wider, less peaked MDFs than Leo I. A simple CEM is not the best fit for any of our galaxies; therefore we also fit the “Best Accretion Model” of Lynden-Bell. For Leo II, IC 1613, and Phoenix we find similar accretion parameters for the CEM even though they all have different effective yields, masses, star formation histories, and morphologies. We suggest that the dynamical history of a galaxy is reflected in the MDF, where broad MDFs are seen in galaxies that have chemically evolved in relative isolation and narrowly peaked MDFs are seen in galaxies that have experienced more complicated dynamical interactions concurrent with their chemical evolution.
Energy Technology Data Exchange (ETDEWEB)
Twidell, J. [De Montfort Univ., Leicester (United Kingdom)
1995-07-01
This document introduces the proceedings of the East Midland Universities Renewable Energy Group, a forum for young post-graduate students. The conference included papers on wind power and small-scale hydroelectric power as sources for electric power, including theoretical investigations of wind turbine structures and control and analysis of electric motors adapted as generators for micro-hydro sets, the strategy for micro-hydro developments and the integration of wind and photovoltaic power, backed up by combined heat and power plant. (UK)
Application of Maximum Entropy Distribution to the Statistical Properties of Wave Groups
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The new distributions of the statistics of wave groups based on the maximum entropy principle are presented. The maximum entropy distributions appear to be superior to conventional distributions when applied to a limited amount of information. Its applications to the wave group properties show the effectiveness of the maximum entropy distribution. FFT filtering method is employed to obtain the wave envelope fast and efficiently. Comparisons of both the maximum entropy distribution and the distribution of Longuet-Higgins (1984) with the laboratory wind-wave data show that the former gives a better fit.
Power system services provided by inverter connected distributed energy resources
DEFF Research Database (Denmark)
For the last few years there has been a significant increase of DER units in Denmark, of those units more and more are connected to the power system using inverters. These inverter connected units have the potential to support the electrical power system with various power system services. One of...... of the services that can be provided is local voltage support. This brings up the question of how the voltage support function is implemented to control multiple DER units as well as how the response of the units can be estimated and evaluated....
Noguchi, Toshihiko; Imoto, Masaru; Sato, Yoshikazu
This paper proposes a novel three-phase power distribution system feeding trapezoidal voltages to various power electronic loads with diode rectifier front-ends. The network distributes trapezoidal voltages generated by synchronous superposition of wave-shaping voltages onto sinusoidal voltages available from a utility power grid. The power distribution by the trapezoidal voltages allows reducing harmonics of the line currents without electronic switching devices because of a spontaneously widened conduction period of the current waveforms. The reduction of the harmonic currents also contributes to improve total power factor at the load input terminals and efficiency of the power transmission cables. Since the diodes of the rectifiers successively commutate the trapezoidal waves during periods of their flat parts, not only total harmonic distortion of the currents is improved, but also voltage ripple across the dc-buses of the rectifiers can effectively be reduced with less filter capacitors. In addition, the system offers an uninterruptible power supply function by immediately changing its outputs from the wave-shaping voltages to the trapezoidal voltages when interruption occurs in the power grid. In this paper, a prototype of the system is experimentally examined from various angles of operating characteristics and test results are presented to prove feasibility of the proposed system.
Science Research Group Leader's Power and Members' Compliance and Satisfaction with Supervision
Meng, Yi; He, Jia; Luo, Changkun
2014-01-01
This study investigated the correlations between science research group members' perceptions of power bases used by their group (lab, team) leader (coercive, reward, legitimate, expert and referent) and the effect of those perceptions on group members' attitudinal compliance, behavioral compliance, and satisfaction with supervision. Participants…
Self-Powered WSN for Distributed Data Center Monitoring
Directory of Open Access Journals (Sweden)
Davide Brunelli
2016-01-01
Full Text Available Monitoring environmental parameters in data centers is gathering nowadays increasing attention from industry, due to the need of high energy efficiency of cloud services. We present the design and the characterization of an energy neutral embedded wireless system, prototyped to monitor perpetually environmental parameters in servers and racks. It is powered by an energy harvesting module based on Thermoelectric Generators, which converts the heat dissipation from the servers. Starting from the empirical characterization of the energy harvester, we present a power conditioning circuit optimized for the specific application. The whole system has been enhanced with several sensors. An ultra-low-power micro-controller stacked over the energy harvesting provides an efficient power management. Performance have been assessed and compared with the analytical model for validation.
Simulation Environment for Power Management and Distribution Development Project
National Aeronautics and Space Administration — The overall objective of this research project is to investigate autonomous control architectures for spacecraft power systems. Such techniques will be critical for...
Self-Powered WSN for Distributed Data Center Monitoring
Brunelli, Davide; Passerone, Roberto; Rizzon, Luca; Rossi, Maurizio; Sartori, Davide
2016-01-01
Monitoring environmental parameters in data centers is gathering nowadays increasing attention from industry, due to the need of high energy efficiency of cloud services. We present the design and the characterization of an energy neutral embedded wireless system, prototyped to monitor perpetually environmental parameters in servers and racks. It is powered by an energy harvesting module based on Thermoelectric Generators, which converts the heat dissipation from the servers. Starting from the empirical characterization of the energy harvester, we present a power conditioning circuit optimized for the specific application. The whole system has been enhanced with several sensors. An ultra-low-power micro-controller stacked over the energy harvesting provides an efficient power management. Performance have been assessed and compared with the analytical model for validation. PMID:26729135
Self-Powered WSN for Distributed Data Center Monitoring.
Brunelli, Davide; Passerone, Roberto; Rizzon, Luca; Rossi, Maurizio; Sartori, Davide
2016-01-02
Monitoring environmental parameters in data centers is gathering nowadays increasing attention from industry, due to the need of high energy efficiency of cloud services. We present the design and the characterization of an energy neutral embedded wireless system, prototyped to monitor perpetually environmental parameters in servers and racks. It is powered by an energy harvesting module based on Thermoelectric Generators, which converts the heat dissipation from the servers. Starting from the empirical characterization of the energy harvester, we present a power conditioning circuit optimized for the specific application. The whole system has been enhanced with several sensors. An ultra-low-power micro-controller stacked over the energy harvesting provides an efficient power management. Performance have been assessed and compared with the analytical model for validation.
Simulation Environment for Power Management and Distribution Development Project
National Aeronautics and Space Administration — The overall objective of this research project is to investigate an autonomous and online control structure for finite-inertia power systems (dc and ac) with a...
Development of An On-Line, Core Power Distribution Monitoring System
Energy Technology Data Exchange (ETDEWEB)
Tunc ALdemir; Don Miller; Peng Wang
2007-10-02
The objective of the proposed work was to develop a software package that can construct in three-dimensional core power distributions using the signals from constant temperature power sensors distributed in the reactor core. The software developed uses a mode-based state/parameter estmation technique that is particularly attractive when there are model uncertainties and/or large signal noise. The software yields the expected value of local power at the detector locations and points in between, as well as the probability distribution of the local power density
Exploiting ancillary services from distributed generation - perspectives for the Danish power system
DEFF Research Database (Denmark)
Nyeng, Preben; Pedersen, Knud Ole Helgesen; Østergaard, Jacob
2007-01-01
The share of the electric power production originating from distributed energy resources has rapidly increased during the recent past. However when it comes to ancillary services necessary to ensure the stability and appropriate operation of the power system, the distributed energy resources take...... a very passive role. This paper outlines suggestions on how to activate the potential of ancillary services from distributed energy resources, thereby exploiting their ability to contribute to power system operation. Furthermore, methods for integrating the ancillary service delivery into a deregulated...... power system are proposed and evaluated....
Distributed Energy Systems with Wind Power and Energy Storage
Korpås, Magnus
2004-01-01
The topic of this thesis is the study of energy storage systems operating with wind power plants. The motivation for applying energy storage in this context is that wind power generation is intermittent and generally difficult to predict, and that good wind energy resources are often found in areas with limited grid capacity. Moreover, energy storage in the form of hydrogen makes it possible to provide clean fuel for transportation. The aim of this work has been to evaluate how local energy s...
Distributed Energy Systems with Wind Power and Energy Storage
Korpås, Magnus
2004-01-01
The topic of this thesis is the study of energy storage systems operating with wind power plants. The motivation for applying energy storage in this context is that wind power generation is intermittent and generally difficult to predict, and that good wind energy resources are often found in areas with limited grid capacity. Moreover, energy storage in the form of hydrogen makes it possible to provide clean fuel for transportation. The aim of this work has been to evaluate how local energy s...
2011-07-28
... Energy Regulatory Commission PJM Interconnection, L.L.C., PJM Power Providers Group v. PJM... Load Group, PJM Power Providers Group, and PSEG Companies. All interested parties are invited to attend... Load Group Dr. Roy Shanker, Consultant, PJM Power Providers Group Dr. William Hogan, Professor,...
Digital Repository Service at National Institute of Oceanography (India)
Khare, N.; Sinha, R.; Rai, A.K.; Nigam, R.
, the population was further placed into two broad morpho-groups namely, angular-asymmetrical and rounded-symmetrical. The surficial distribution of these groups revealed that angular-asymmetrical forms are abundant in relatively deeper region whereas rounded...
Distribution of ABO blood groups and rhesus factor in a Large Scale ...
African Journals Online (AJOL)
J. Torabizade maatoghi
2015-08-20
Aug 20, 2015 ... a Iranian Blood Transfusion Organization Research Center, Iran b Ahvaz Jundishapur ... Knowing the distribution of blood groups in different blood collection .... groups is of utmost importance due to location of the province.
A High Power Density DC-DC Converter for Distributed PV Architectures
Energy Technology Data Exchange (ETDEWEB)
Agamy, Mohammed S; Chi, Song; Elasser, Ahmed; Harfman-Todorovic, Maja; Jiang, Yan; Mueller, Frank; Tao, Fengfeng
2012-06-01
In order to maximize solar energy harvesting capabilities, power converters have to be designed for high efficiency and good MPPT and voltage/current performance. When many converters are used in distributed systems, power density also becomes an important factor as it allows for simpler system integration. In this paper a high power density string dc-dc converter suitable for distributed medium to large scale PV installation is presented. A simple partial power processing topology, implemented with all silicon carbide devices provides high efficiency as well as high power density. A 3.5kW, 100kHz converter is designed and tested to verify the proposed methods.
A MILP-Based Distribution Optimal Power Flow Model for Microgrid Operation
Energy Technology Data Exchange (ETDEWEB)
Liu, Guodong [ORNL; Starke, Michael R [ORNL; Zhang, Xiaohu [ORNL; Tomsovic, Kevin [University of Tennessee, Knoxville (UTK)
2016-01-01
This paper proposes a distribution optimal power flow (D-OPF) model for the operation of microgrids. The proposed model minimizes not only the operating cost, including fuel cost, purchasing cost and demand charge, but also several performance indices, including voltage deviation, network power loss and power factor. It co-optimizes the real and reactive power form distributed generators (DGs) and batteries considering their capacity and power factor limits. The D-OPF is formulated as a mixed-integer linear programming (MILP). Numerical simulation results show the effectiveness of the proposed model.
Design and Simulation of a Three Phase Power Converter Connected To a Distribution System
Directory of Open Access Journals (Sweden)
M. Kotaiah
2014-09-01
Full Text Available The distributed generation systems based on renewable energy sources (photovoltaic, fuel cells, and storage systems such as ultra capacitors and batteries are of great interest due to their low environmental impact and technical advantages such as improvements in voltage levels and reduced power losses when a distributed generation system is installed in radial lines. Two control algorithms were proposed to improve the grid-connected and intentional-islanding operations methods, in which the distributed generation system must detect the situation and switch from power or current to voltage as a control variable to provide constant rms voltage to the local loads. The power flow between the grid and the distributed generation is controlled by applying a power/voltage method that regulates the amplitude and the displacement of the grid voltage synthesized by the distributed generation, while a phase-locked loop algorithm is used to synchronize the grid and distributed generation.
Distributed energy systems with wind power and energy storage
Energy Technology Data Exchange (ETDEWEB)
Korpaas, Magnus
2004-07-01
The topic of this thesis is the study of energy storage systems operating with wind power plants. The motivation for applying energy storage in this context is that wind power generation is intermittent and generally difficult to predict, and that good wind energy resources are often found in areas with limited grid capacity. Moreover, energy storage in the form of hydrogen makes it possible to provide clean fuel for transportation. The aim of this work has been to evaluate how local energy storage systems should be designed and operated in order to increase the penetration and value of wind power in the power system. Optimization models and sequential and probabilistic simulation models have been developed for this purpose. Chapter 3 presents a sequential simulation model of a general wind hydrogen energy system. Electrolytic hydrogen is used either as a fuel for transportation or for power generation in a stationary fuel cell. The model is useful for evaluating how hydrogen storage can increase the penetration of wind power in areas with limited or no transmission capacity to the main grid. The simulation model is combined with a cost model in order to study how component sizing and choice of operation strategy influence the performance and economics of the wind-hydrogen system. If the stored hydrogen is not used as a separate product, but merely as electrical energy storage, it should be evaluated against other and more energy efficient storage options such as pumped hydro and redox flow cells. A probabilistic model of a grid-connected wind power plant with a general energy storage unit is presented in chapter 4. The energy storage unit is applied for smoothing wind power fluctuations by providing a firm power output to the grid over a specific period. The method described in the chapter is based on the statistical properties of the wind speed and a general representation of the wind energy conversion system and the energy storage unit. This method allows us to
The far-reaching effects of power: at the individual, dyadic, and group levels
Galinsky, A.D.; Chou, E.Y.; Halevy, N.; Van Kleef, G.A.; Neale, M.A.; Mannix, E.A.
2012-01-01
Purpose - This chapter provides a framework that captures the fundamental impacts of power at the individual, dyadic, small group, and organizational levels. Within each level, we trace the psychological, cognitive, and behavioral consequences of having or lacking power. Approach - We integrate theo
77 FR 11515 - Application To Export Electric Energy; Pilot Power Group, Inc.
2012-02-27
... Application To Export Electric Energy; Pilot Power Group, Inc. AGENCY: Office of Electricity Delivery and...) has applied for authority to transmit electric energy from the United States to Mexico pursuant to... Power for authority to transmit electric energy from the United States to Mexico for five years as...
Modeling and Simulation of Power Distribution System in More Electric Aircraft
Directory of Open Access Journals (Sweden)
Zhangang Yang
2015-01-01
Full Text Available The More Electric Aircraft concept is a fast-developing trend in modern aircraft industry. With this new concept, the performance of the aircraft can be further optimized and meanwhile the operating and maintenance cost will be decreased effectively. In order to optimize the power system integrity and have the ability to investigate the performance of the overall system in any possible situations, one accurate simulation model of the aircraft power system will be very helpful and necessary. This paper mainly introduces a method to build a simulation model for the power distribution system, which is based on detailed component models. The power distribution system model consists of power generation unit, transformer rectifier unit, DC-DC converter unit, and DC-AC inverter unit. In order to optimize the performance of the power distribution system and improve the quality of the distributed power, a feedback control network is designed based on the characteristics of the power distribution system. The simulation result indicates that this new simulation model is well designed and it works accurately. Moreover, steady state performance and transient state performance of the model can fulfill the requirements of aircraft power distribution system in the realistic application.
Constructing the probability distribution function for the total capacity of a power system
Energy Technology Data Exchange (ETDEWEB)
Vasin, V.P.; Prokhorenko, V.I.
1980-01-01
The difficulties involved in constructing the probability distribution function for the total capacity of a power system consisting of numerous power plants are discussed. A method is considered for the approximate determination of such a function by a Monte Carlo method and by exact calculation based on special recursion formulas on a particular grid of argument values. It is shown that there may be significant deviations between the true probability distribution and a normal distribution.
Power Management for A Distributed Wireless Health Management Architecture
National Aeronautics and Space Administration — Distributed wireless architectures for prognostics is an important enabling step in prognostic research in order to achieve feasible real-time system health...
An Improved Harmony Search Algorithm for Power Distribution Network Planning
Directory of Open Access Journals (Sweden)
Wei Sun
2015-01-01
Full Text Available Distribution network planning because of involving many variables and constraints is a multiobjective, discrete, nonlinear, and large-scale optimization problem. Harmony search (HS algorithm is a metaheuristic algorithm inspired by the improvisation process of music players. HS algorithm has several impressive advantages, such as easy implementation, less adjustable parameters, and quick convergence. But HS algorithm still has some defects such as premature convergence and slow convergence speed. According to the defects of the standard algorithm and characteristics of distribution network planning, an improved harmony search (IHS algorithm is proposed in this paper. We set up a mathematical model of distribution network structure planning, whose optimal objective function is to get the minimum annual cost and constraint conditions are overload and radial network. IHS algorithm is applied to solve the complex optimization mathematical model. The empirical results strongly indicate that IHS algorithm can effectively provide better results for solving the distribution network planning problem compared to other optimization algorithms.
Power management and distribution equipment developed for space applications
Thornton, R. D.
Some of the current developments in the area of dc power switching and conversion equipment are described for Space Station Freedom. The equipment includes 120-Vdc remote power controllers (RPCs) rated at 1 kW, 5 kW, and 15 kW; 25-kW and 50-kW remote bus isolators (RBIs), both uni- and bi-directional; a 1-kW 120-Vdc/28-Vdc converter; and a 250-Adc differential fault protection module. Most of this equipment was designed to allow communication with a power system controller via a full MIL-STD-1553B data bus interface. The standard interface/data acquisition card developed for the described hardware allows remote control of the equipment as well as monitoring of system loads and voltages.
Renormalization group approach to power-law modeling of complex metabolic networks.
Hernández-Bermejo, Benito
2010-08-07
In the modeling of complex biological systems, and especially in the framework of the description of metabolic pathways, the use of power-law models (such as S-systems and GMA systems) often provides a remarkable accuracy over several orders of magnitude in concentrations, an unusually broad range not fully understood at present. In order to provide additional insight in this sense, this article is devoted to the renormalization group analysis of reactions in fractal or self-similar media. In particular, the renormalization group methodology is applied to the investigation of how rate-laws describing such reactions are transformed when the geometric scale is changed. The precise purpose of such analysis is to investigate whether or not power-law rate-laws present some remarkable features accounting for the successes of power-law modeling. As we shall see, according to the renormalization group point of view the answer is positive, as far as power-laws are the critical solutions of the renormalization group transformation, namely power-law rate-laws are the renormalization group invariant solutions. Moreover, it is shown that these results also imply invariance under the group of concentration scalings, thus accounting for the reported power-law model accuracy over several orders of magnitude in metabolite concentrations. Copyright 2010 Elsevier Ltd. All rights reserved.
Photovoltaic Power System and Power Distribution Demonstration for the Desert RATS Program
Colozza, Anthony; Jakupca, Ian; Mintz, Toby; Herlacher, Mike; Hussey, Sam
2012-01-01
A stand alone, mobile photovoltaic power system along with a cable deployment system was designed and constructed to take part in the Desert Research And Technology Studies (RATS) lunar surface human interaction evaluation program at Cinder Lake, Arizona. The power system consisted of a photovoltaic array/battery system. It is capable of providing 1 kW of electrical power. The system outputs were 48 V DC, 110 V AC, and 220 V AC. A cable reel with 200 m of power cable was used to provide power from the trailer to a remote location. The cable reel was installed on a small trailer. The reel was powered to provide low to no tension deployment of the cable. The cable was connected to the 220 V AC output of the power system trailer. The power was then converted back to 110 V AC on the cable deployment trailer for use at the remote site. The Scout lunar rover demonstration vehicle was used to tow the cable trailer and deploy the power cable. This deployment was performed under a number of operational scenarios, manned operation, remote operation and tele-robotically. Once deployed, the cable was used to provide power, from the power system trailer, to run various operational tasks at the remote location.
DEFF Research Database (Denmark)
Zecchino, Antonio; Marinelli, Mattia; Træholt, Chresten
2017-01-01
The increasing success of electric vehicles is bringing new technical challenges to power system operators. This work intends to provide guidelines for distribution system operators in terms of reactive power requirements when evaluating and authorizing electric vehicles supply equipment with fast...... the amount of reactive power that an individual electric vehicle is expected to provide when connected to a low voltage feeder, in order to benefit of the desired voltage rise effect in comparison to the case of unitary power factor....
System Implications of the Different Powering Distributions for the ATLAS Upgrade Strips Tracker
Díez, S
2012-01-01
This paper compares the two novel approaches for the power distribution of the ATLAS Upgrade strips tracker modules, serial and DC-DC powering, from the point of view of a system. Numerous variables have been taken into account, such as total power dissipation and power efficiency, system reliability and protection, noise performances, impact on the material budget of the tracker, and services needs and re-usability.
Power distribution in the snowflake divertor in TCV
Reimerdes, H.; G.P. Canal,; Duval, B. P.; Labit, B.; Lunt, T.; Vijvers, W. A. J.; Coda, S.; De Temmerman, G.; Morgan, T. W.; Nespoli, F.; Tal, B.; the TCV Team,
2013-01-01
TCV experiments demonstrate the basic power exhaust properties of the snowflake (SF) plus and SF minus divertor configurations by measuring the heat fluxes at each of their four divertor legs. The measurements indicate an enhanced transport into the private flux region and a reduction of peak heat f
Protecting Intelligent Distributed Power Grids against Cyber Attacks
Energy Technology Data Exchange (ETDEWEB)
Dong Wei; Yan Lu; Mohsen Jafari; Paul Skare; Kenneth Rohde
2010-12-31
Like other industrial sectors, the electrical power industry is facing challenges involved with the increasing demand for interconnected operations and control. The electrical industry has largely been restructured due to deregulation of the electrical market and the trend of the Smart Grid. This moves new automation systems from being proprietary and closed to the current state of Information Technology (IT) being highly interconnected and open. However, while gaining all of the scale and performance benefits of IT, existing IT security challenges are acquired as well. The power grid automation network has inherent security risks due to the fact that the systems and applications for the power grid were not originally designed for the general IT environment. In this paper, we propose a conceptual layered framework for protecting power grid automation systems against cyber attacks. The following factors are taken into account: (1) integration with existing, legacy systems in a non-intrusive fashion; (2) desirable performance in terms of modularity, scalability, extendibility, and manageability; (3) alignment to the 'Roadmap to Secure Control Systems in the Energy Sector' and the future smart grid. The on-site system test of the developed prototype security system is briefly presented as well.
Distributed MPC applied to power demand side control
Larsen, G.K.H.; Pons, J.; Achterop, S.; Scherpen, J.M.A.
2013-01-01
In the future, global energy balance of a smart grid system can be achieved by its agents deciding on their own power demand locally and the exchange of these decisions. In this paper, we model a network of households with washing machine programs that can be shifted in time so that the overall powe
Distributed Electrical Power Generation: Summary of Alternative Available Technologies
2003-09-01
Heliostats Heliostats , or solar concentrators, can be used to collect heat to power Stirling en- gines. They use a lens or reflectors to concentrate...Configurations ......................................................................................................... 38 Heliostats ...equipment is possible in the form of cooling and heating ; enhancing a 20 to 35 percent generation efficiency to between 75 and 80 percent. DG increases
User-friendly Tool for Power Flow Analysis and Distributed ...
African Journals Online (AJOL)
Akorede
an efficient and reliable manner – with minimal energy loss cost. ... recent renewed global interest in DG since the conventional ... 1Department of Electrical & Electronic Engineering, Universiti Putra Malaysia, ... in increase in the power frequency beyond the preset upper ...... New Jersey, USA, Pearson Education, Inc.,.
Modeling, control, and dispatch of photovoltaic-based power distribution systems
Carrasco, Miguel
Small-scale generators, also called distributed generators (DGs), are primed to play a central role in future distribution systems. If properly integrated, DGs present two main advantages: (i) they help decongest existing transmission grids; and (ii) CO2 emissions are reduced since most DGs are based on renewables like wind and solar. Their integration into distribution systems is one of the main challenges the power industry will be facing in the coming years. Photovoltaic (PV) power generation represents a key technology for realizing the DG concept. In this dissertation, technical solutions are developed that enable an increased penetration of PV systems, while improving the efficiency, reliability, and power quality of power distribution grids. The presented research spans from PV array modeling, parameter identification and estimation methods, through advanced control strategies for the power electronic interfaces, to system--level optimal dispatch strategies. Simulation-based and experimental validation results show the performance of the proposed techniques.
Power-law distribution functions derived from maximum entropy and a symmetry relationship
Peterson, G J
2011-01-01
Power-law distributions are common, particularly in social physics. Here, we explore whether power-laws might arise as a consequence of a general variational principle for stochastic processes. We describe communities of 'social particles', where the cost of adding a particle to the community is shared equally between the particle joining the cluster and the particles that are already members of the cluster. Power-law probability distributions of community sizes arise as a natural consequence of the maximization of entropy, subject to this 'equal cost sharing' rule. We also explore a generalization in which there is unequal sharing of the costs of joining a community. Distributions change smoothly from exponential to power-law as a function of a sharing-inequality quantity. This work gives an interpretation of power-law distributions in terms of shared costs.
Application of Infrared Thermography in Power Distribution System
Directory of Open Access Journals (Sweden)
Anwer Ali Sahito
2014-07-01
Full Text Available Electricity sector of Pakistan is facing daunting energy crisis. Generation deficit results in long duration of load shedding throughout the country. Old aged distribution system, lack of maintenance and equipment failure cause long unplanned outages and frequent supply interruptions. HESCO (Hyderabad Electric Supply Company is facing high technical losses, supply interruption and financial loss due to transformer damages. Infrared Thermography is non-contact, safe and fast measure for distribution system inspection. In this paper, thermographic inspection for different distribution system equipment is carried out to identify possible developed faults. It is observed that IR (Infrared thermography is effective measure for detecting developed faulty conditions at the initial stages to avoid unplanned outages
Planning criteria for power distribution networks; Planungskriterien fuer Verteilungsnetze
Energy Technology Data Exchange (ETDEWEB)
Klockhaus, H. [RWE Energie AG, Essen (Germany)
1997-01-01
For decades now, power network planning has been a task that had to consider consumption growth rates of 7% and above, which corresponds to a 100% increase within a period of ten years. Hence the major task of power network planning was to achieve network expansion at lowest possible cost in response to increased demand and for ensuring reliable power supply. Other than today, it has been easier then, approx. until the early 1970s, to implement general planning decisions by way of releatively immediate action, as for instance the change in voltage levels in medium high voltage systems from 20 kV to 20 kV. As a result of the oil crisis, economizing efforts everywhere cut off the power industry from the macroeconomic growth trends. Today, electric power consumption in Germany practically remains at level. Network expansion planning activities are restricted to new installations connecting or expanding existing transmission lines to newly built areas or town districts. For some years it looked as if network planning was falling behind in importance and network operation planning coming to the foreground. Meanwhile however, new and comprehensive tasks and activities have cropped up in the power market which demand optimization and best possible achievement to the benefit of the customers and the utilities. (orig.) [Deutsch] Fuer Jahrzehnte war die Aufgabe der Netzplanung gekennzeichnet durch intensiven Zuwachs an Energieverbrauch. Bei Zuwachsraten von 7% und darueber, was einer Verdoppelung binnen zehn Jahren entsprach, war eine der vordringlichsten Aufgaben der Netzplanung die Sicherstellung eines moeglichst kostenguenstigen Netzausbaus zur Gewaehrleistung der Versorgung. Leichter als heute konnten in dieser Zeit, die bis in die 70er Jahre andauerte, Grundsatzplanungen mit eingreifenden Massnahmen umgesetzt werden, etwa die Umstellung von Spannungsstufen in Mittelspannungsenetzen, z.B. von 10 kV auf 20 kV. In den 70er Jahren begann mit den Einsparbemuehungen als Folge
High Power test of a low group velocity X-band Accelerator Structure for CLIC
Döbert, S; Riddone, G; Taborelli, M; Wuensch, W; Zennaro, R; Fukuda, S; Higashi, Y; Higo, T; Matsumoto, S; Ueno, K; Yokoyama, K; Adolphsen, C; Dolgashev, V; Laurent, L; Lewandowski, J; Tantawi, S; Wang, F; Wang, JW
2008-01-01
In recent years evidence has been found that the maximum sustainable gradient in an accelerating structure depends on the rf power flow through the structure. The CLIC study group has consequently designed a new prototype structure for CLIC with a very low group velocity, input power and average aperture ( = 0.13). The 18 cell structure has a group velocity of 2.6 % at the entrance and 1 % at the last cell. Several of these structures have been made in a collaboration between KEK, SLAC and CERN. A total of five brazed-disk structures and two quadrant structures have been made. The high power results of the first KEK/SLAC built structure is presented which reached an unloaded gradient in excess of 100 MV/m at a pulse length of 230 ns with a breakdown rate below 10-6 per meter active length. The high-power testing was done using the NLCTA facility at SLAC.
DEFF Research Database (Denmark)
Chen, Shuheng; Hu, Weihao; Su, Chi
2015-01-01
A new and efficient methodology for optimal reactive power and voltage control of distribution networks with distributed generators based on fuzzy adaptive hybrid PSO (FAHPSO) is proposed. The objective is to minimize comprehensive cost, consisting of power loss and operation cost of transformers...... and capacitors, and subject to constraints such as minimum and maximum reactive power limits of distributed generators, maximum deviation of bus voltages, maximum allowable daily switching operation number (MADSON). Particle swarm optimization (PSO) is used to solve the corresponding mixed integer non......-linear programming problem (MINLP) and the hybrid PSO method (HPSO), consisting of three PSO variants, is presented. In order to mitigate the local convergence problem, fuzzy adaptive inference is used to improve the searching process and the final fuzzy adaptive inference based hybrid PSO is proposed. The proposed...
Introducing distributed learning approaches in wind power forecasting
DEFF Research Database (Denmark)
Pinson, Pierre
2016-01-01
Renewable energy forecasting is now of core interest to both academics, who continuously propose new forecast methodologies, and forecast users for optimal operations and participation in electricity markets. In view of the increasing amount of data being collected at power generation sites, thanks...... to substantial deployment of generating capacities and increased temporal resolution, it may now be possible to build large models accounting for all space-time dependencies. This will eventually allow to significantly improve the quality of short-term renewable power forecasts. However, in practice, it is often...... to ever share any data, by decomposing the original large learning problem into a number of small learning problems that can be solved in a decentralized manner. As an example, emphasis is placed on Lasso-type estimation of autoregressive models with offsite observations. Different applications on medium...
Introducing distributed learning approaches in wind power forecasting
Pinson, Pierre
2016-01-01
Renewable energy forecasting is now of core interest to both academics, who continuously propose new forecast methodologies, and forecast users for optimal operations and participation in electricity markets. In view of the increasing amount of data being collected at power generation sites, thanks to substantial deployment of generating capacities and increased temporal resolution, it may now be possible to build large models accounting for all space-time dependencies. This will eventually a...
Large space systems technology electronics: Data and power distribution
Dunbar, W. G.
1980-01-01
The development of hardware technology and manufacturing techniques required to meet space platform and antenna system needs in the 1980s is discussed. Preliminary designs for manned and automatically assembled space power system cables, connectors, and grounding and bonding materials and techniques are reviewed. Connector concepts, grounding design requirements, and bonding requirements are discussed. The problem of particulate debris contamination for large structure spacecraft is addressed.
Distributed Leadership: The Uses and Abuses of Power
Lumby, Jacky
2013-01-01
In about a decade the theory of distributed leadership has moved from a tool to better understand the ecology of leadership to a widely prescribed practice. This article considers how to account for its spread and dominance and what purpose it serves. The concept offers an enticing suggestion of including more in leadership, and even sometimes…
Analysis of distributed cooled high power millimeter wave windows
Energy Technology Data Exchange (ETDEWEB)
Nelson, S.D.; Caplan, M.; Reitter, T.A.
1995-09-09
The sectional high-frequency (100--170 GHz) distributed cooled window has been investigated both electromagnetically and thermally previously using computational electromagnetics (EM) and thermal codes. Recent data describes the relationship to some experimental data for the window. Results are presented for time domain CW EM analyses and CW thermal and stress calculations.
Price-based control for electrical power distribution system
Jafarian, Matin; Scherpen, Jacquelien M.A.; Aiello, Marco; Carloni, Raffaella; Jeltsema, Dimitri; Lazar, Mircea
2016-01-01
In the coming years, the exploitation of Renewable Energy Sources (RES), i.e. wind and solar sources, will increase significantly. Comparing to fossil-fuel sources, RES are produced and distributed in a more decentralized fashion and their availability mainly depends on the climate and weather condi
Price-based control for electrical power distribution system
Jafarian, Matin; Scherpen, Jacquelien M.A.; Aiello, Marco; Carloni, Raffaella; Jeltsema, Dimitri; Lazar, Mircea
2016-01-01
In the coming years, the exploitation of Renewable Energy Sources (RES), i.e. wind and solar sources, will increase significantly. Comparing to fossil-fuel sources, RES are produced and distributed in a more decentralized fashion and their availability mainly depends on the climate and weather condi
A Low Power Single Phase Clock Distribution Multiband Network
Directory of Open Access Journals (Sweden)
Dr.A.Muruganandham#1,
2014-02-01
Full Text Available Frequency synthesizer is one of the important elements for wireless communication application. The speed of VCO and prescaler determines how fast the frequency synthesizer is. A dual modulus prescaler contains logic gates and flip-flops. This project aim for developing a low power single clock multiband network which will supply for the multi clock domain network. The multiband divider consists of a proposed wideband multi modulus 32/33/47/48 prescaler and an improved bitcell for swallow (S counter and can divide the frequencies in the three bands of 2.4–2.484 GHz, 5.15–5.35 GHz, and 5.725– 5.825 GHz with a resolution selectable from 1 to 25 MHz The proposed multiband flexible divider is silicon verified and consumes power of 0.96 and 2.2 mW in 2.4- and 5-GHz bands, respectively, when operated at 1.8-V power supply.
DEFF Research Database (Denmark)
Esparza, Miguel; Segundo-Ramirez, Juan; Nunez, Ciro
2017-01-01
The undesirable harmonic distortion produced by distributed generation units (DGUs) based on power electronic inverters presents operating and power quality challenges in electric systems. ‡e level of distortion depends on the internal elements of the DGUs as well as on the characteristics...... of the grid, loads, controls, among others. ‡is paper presents a comprehensive method, focused on power quality indexes and e�ciency for the design of micro-grids with multiple DGUs interconnected to the AC grid through three phase multi-Megawatt medium-voltage PWM voltage source inverters (PWM-VSI). ‡e...
DEFF Research Database (Denmark)
Blaabjerg, Frede; Vilathgamuwa, D. M.; Loh, Poh Chiang
2009-01-01
Distributed generation (DG) systems are usually connected to the grid using power electronic converters. Power delivered from such DG sources depends on factors like energy availability and load demand. The converters used in power conversion do not operate with their full capacity all the time......-stage buck-boost inverter, recently proposed Z-source inverter (ZSI) is a good candidate for future DG systems. This paper presents a controller design for a ZSI-based DG system to improve power quality of distribution systems. The proposed control method is tested with simulation results obtained using...
DEFF Research Database (Denmark)
Wu, Hongfei; Sun, Kai; Chen, Min;
2013-01-01
The unbalanced temperature distribution influences the power output of thermoelectric generator (TEG) system, which leads to mismatch power among TEG modules. This mismatch power degrades the energy efficiency of TEG systems based on the series-connected TEG modules. A hybrid centralized-distribu......The unbalanced temperature distribution influences the power output of thermoelectric generator (TEG) system, which leads to mismatch power among TEG modules. This mismatch power degrades the energy efficiency of TEG systems based on the series-connected TEG modules. A hybrid centralized...... the proposed system, which benefits for implementing high MPPT efficiency and high conversion efficiency simultaneously. A hybrid MPPT control strategy is proposed for this HCD power conditioning system. The characteristics, circuit implementation and operation principles of the proposed system are presented...
Stationarity of the inter-event power-law distributions
Gandica, Yerali; Aidos, Fernando Sampaio Dos; Lambiotte, Renaud; Carletti, and Timoteo
2016-01-01
A number of human activities exhibit a bursty pattern, namely periods of very high activity that are followed by rest periods. Records of these processes generate time series of events whose inter-event times follow a probability distribution that displays a fat tail. The grounds for such phenomenon are not yet clearly understood. In the present work we use the freely available Wikipedia editing records to unravel some features of this phenomenon. We show that even though the probability to start editing is conditioned by the circadian 24 hour cycle, the conditional probability for the time interval between successive edits at a given time of the day is independent from the latter. We confirm our findings with the activity of posting on the social network Twitter. Our result suggests there is an intrinsic humankind scheduling pattern: after overcoming the encumbrance to start an activity, there is a robust distribution of new related actions, which does not depend on the time of day.
An Identity-Based Group Key Agreement Proto col for Low-Power Mobile Devices
Institute of Scientific and Technical Information of China (English)
TENG Jikai; WU Chuankun
2016-01-01
In wireless mobile networks, group mem-bers join and leave the group frequently, a dynamic group key agreement protocol is required to provide a group of users with a shared secret key to achieve cryptographic goal. Most of previous group key agreement protocols for wireless mobile networks are static and employ traditional PKI. This paper presents an ID-based dynamic authen-ticated group key agreement protocol for wireless mobile networks. In Setup and Join algorithms, the protocol re-quires two rounds and each low-power node transmits con-stant size of messages. Furthermore, in Leave algorithm, only one round is required and none of low-power nodes is required to transmit any message, which improves the eﬃ-ciency of the entire protocol. The protocol’s AKE-security with forward secrecy is proved under Decisional bilinear in-verse Diﬃe-Hellman (DBIDH) assumption. It is addition-ally proved to be contributory.
Fast restoration of large area breakdown for power distribution systems
Institute of Scientific and Technical Information of China (English)
LIU Jian; XU Jing-qiu; CHENG Hong-li
2006-01-01
An adjacent table-based simplified model of distribution networks containing medium voltage buses of a substation is established.Identification of bus outage and the condition to start fast restoration procedure are discussed.A complex load shading parameter is set up to describe various load shading schemes.The imaginary part of the load shading parameter describes the states of switches of load shading schemes while the real part is the corresponding amount of shaded load.A new concept of independent tripping operation is also put forward.The procedure to search the operation with the least amount of shaded load for a feeder and a connected domain are detailed.The procedure for fast restoration of a large area breakdown of the whole distribution network under emergency states is dealt with using a typical grid distribution network as an example.Results of analysis show that the direct load shading scheme under the most balanced topology is not always the optimal scheme.The proposed method can obtain the optimal operating mode with the least amount of shaded load thus showing its feasibility.
Energy Technology Data Exchange (ETDEWEB)
Usami, Shin; Suzuki, Takayuki; Sasaki, Kenji; Deshimaru, Takehide [Power Reactor and Nuclear Fuel Development Corp., Tsuruga, Fukui (Japan). Monju Construction Office; Nakashima, Fumiaki
1996-09-01
In MONJU, reaction rate distribution measurements were made by foil activation methods from May through September 1994. On the basis of the reaction rate measurement data, the MONJU initial core breeding ratio and the power distribution, etc. were evaluated. As a result, the evaluated values and the calculated values showed good agreement, and we confirmed that the core performance of MONJU and the method of core calculations were satisfactory. (author)
Optimal Power Flow in Islanded Microgrids Using a Simple Distributed Algorithm
DEFF Research Database (Denmark)
Sanseverino, Eleonora Riva; Di Silvestre, Maria Luisa; Badalamenti, Romina
2015-01-01
In this paper, the problem of distributed power losses minimization in islanded distribution systems is dealt with. The problem is formulated in a very simple manner and a solution is reached after a few iterations. The considered distribution system, a microgrid, will not need large bandwidth co...... results of the proposed method on an islanded microgrid. Simulation results of the distributed algorithm are compared to a centralized Optimal Power Flow approach and very small errors can be observed.......In this paper, the problem of distributed power losses minimization in islanded distribution systems is dealt with. The problem is formulated in a very simple manner and a solution is reached after a few iterations. The considered distribution system, a microgrid, will not need large bandwidth...... communication channels, since only closeby nodes will exchange information. The correction of generated active powers is possible by means of the active power losses partition concept that attributes a portion of the overall power losses in each branch to each generator. The experimental part shows the first...
Analysis of Power Quality Based on Real Data and Quality Improvement at Campus Distribution System
Kawasaki, Shoji; Matsuki, Junya; Hayashi, Yasuhiro; Ito, Akitoshi
In recent years, a lot of equipments have been made using the inverter technology from home electric appliances to office automation apparatuses and industrial equipments with the development of power electronics technology. The voltage distortion of a distribution system has increased due to the harmonic currents generated from these apparatuses, and the increase in harmonics continues to be expected. In addition, the distribution system forms the circuit of harmonic distortion expansion by the prevalence of static capacitor without L for power factor improvement. Moreover, the voltage imbalance occurs by diversification of loads or imbalanced connection of single-phase loads. The deterioration of power quality in the distribution system causes various problems such as the overheating of equipments and malfunction of rotating machines. Since the power quality changes according to air temperature and date, it is desirable to measure the voltages and currents continuously for a long time. In this study, the authors focus attention on the distribution system in the University of Fukui campus, and the authors have measured the voltages and currents in the distribution system for a long period with WAMS (Wide Area Measurement System) using NCT (Network Computing Terminal). Based on the obtained data, the authors analyzed the power quality of the campus distribution system from viewpoints of voltage imbalance, current imbalance, voltage THD (Total Harmonic Distortion), and current THD. Furthermore, the improvement effect of power quality of the campus distribution system by exchange of single-phase load connection is described.
Intelligent system to control electric power distribution networks
Directory of Open Access Journals (Sweden)
Pablo CHAMOSO
2016-07-01
Full Text Available The use of high voltage power lines transport involves some risks that may be avoided with periodic reviews as imposed by law in most countries. The objective of this work is to reduce the number of these periodic reviews so that the maintenance cost of power lines is also reduced. To reduce the number of transmission towers (TT to be reviewed, a virtual organization (VO based system of agents is proposed in conjunction with different artificial intelligence methods and algorithms. This system is able to propose a sample of TT from a selected set to be reviewed and to ensure that the whole set will have similar values without needing to review all the TT. As a result, the system provides a software solution to manage all the review processes and all the TT of Spain, allowing the review companies to use the application either when they initiate a new review process for a whole line or area of TT, or when they want to place an entirely new set of TT, in which case the system would recommend the best place and the best type of structure to use.
Digital control of grid connected converters for distributed power generation
Energy Technology Data Exchange (ETDEWEB)
Skjellnes, Tore
2008-07-01
Pulse width modulated converters are becoming increasingly popular as their cost decreases and power rating increases. The new trend of small scale power producers, often using renewable energy sources, has created new demands for delivery of energy to the grid. A major advantage of the pulse width modulated converter is the ability to control the output voltage at any point in the voltage period. This enables rapid response to load changes and non-linear loads. In addition it can shape the voltage in response to the output current to create an outward appearance of a source impedance. This is called a virtual impedance. This thesis presents a controller for a voltage controlled three phase pulse width modulated converter. This controller enables operation in standalone mode, in parallel with other converters in a micro grid, and in parallel with a strong main grid. A time varying virtual impedance is presented which mainly attenuates reactive currents. A method of investigating the overall impedance including the virtual impedance is presented. New net standards have been introduced, requiring the converter to operate even during severe dips in the grid voltage. Experiments are presented verifying the operation of the controller during voltage dips. (Author). 37 refs., 65 figs., 10 tabs
Kodama, Yu; Hamagami, Tomoki
Distributed processing system for restoration of electric power distribution network using two-layered CNP is proposed. The goal of this study is to develop the restoration system which adjusts to the future power network with distributed generators. The state of the art of this study is that the two-layered CNP is applied for the distributed computing environment in practical use. The two-layered CNP has two classes of agents, named field agent and operating agent in the network. In order to avoid conflicts of tasks, operating agent controls privilege for managers to send the task announcement messages in CNP. This technique realizes the coordination between agents which work asynchronously in parallel with others. Moreover, this study implements the distributed processing system using a de-fact standard multi-agent framework, JADE(Java Agent DEvelopment framework). This study conducts the simulation experiments of power distribution network restoration and compares the proposed system with the previous system. We confirmed the results show effectiveness of the proposed system.
Dynamic Multicast Grouping Approach in HLA-Based Distributed Interactive Simulation
Institute of Scientific and Technical Information of China (English)
DAI Zhong-jian; HOU Chao-zhen
2005-01-01
In order to improve the efficiency of data distributed management service in distributed interactive simulation based on high level architecture (HLA) and to reduce the network traffic and save the system resource, the approaches of multicast grouping in HLA-based distributed interactive simulation are discussed. Then a new dynamic multicast grouping approach is proposed. This approach is based on the current publication and subscription region in the process of simulation. The results of simulation experiment show that this approach can significantly reduce the message overhead and use fewer multicast groups.
A Life-Cycle Model of Human Social Groups Produces a U-Shaped Distribution in Group Size.
Directory of Open Access Journals (Sweden)
Gul Deniz Salali
Full Text Available One of the central puzzles in the study of sociocultural evolution is how and why transitions from small-scale human groups to large-scale, hierarchically more complex ones occurred. Here we develop a spatially explicit agent-based model as a first step towards understanding the ecological dynamics of small and large-scale human groups. By analogy with the interactions between single-celled and multicellular organisms, we build a theory of group lifecycles as an emergent property of single cell demographic and expansion behaviours. We find that once the transition from small-scale to large-scale groups occurs, a few large-scale groups continue expanding while small-scale groups gradually become scarcer, and large-scale groups become larger in size and fewer in number over time. Demographic and expansion behaviours of groups are largely influenced by the distribution and availability of resources. Our results conform to a pattern of human political change in which religions and nation states come to be represented by a few large units and many smaller ones. Future enhancements of the model should include decision-making rules and probabilities of fragmentation for large-scale societies. We suggest that the synthesis of population ecology and social evolution will generate increasingly plausible models of human group dynamics.
Patton, Jeff A.
1986-01-01
The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Electrical Power Distribution and Control (EPD and C)/Electrical Power Generation (EPG) hardware. The EPD and C/EPG hardware is required for performing critical functions of cryogenic reactant storage, electrical power generation and product water distribution in the Orbiter. Specifically, the EPD and C/EPG hardware consists of the following components: Power Section Assembly (PSA); Reactant Control Subsystem (RCS); Thermal Control Subsystem (TCS); Water Removal Subsystem (WRS); and Power Reactant Storage and Distribution System (PRSDS). The IOA analysis process utilized available EPD and C/EPG hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode.
DEFF Research Database (Denmark)
Huang, Shaojun; Wu, Qiuwei; Zhao, Haoran
2016-01-01
Renewable energies are increasingly integrated in electric distribution networks and will cause severe overvoltage issues. Smart grid technologies make it possible to use coordinated control to mitigate the overvoltage issues and the optimal power flow (OPF) method is proven to be efficient in th...... profile of the feasible sub-injection (injection of nodes excluding the root/substation node) region...
DEFF Research Database (Denmark)
Demirok, Erhan; Sera, Dezso; Teodorescu, Remus
2014-01-01
Grid-connected photovoltaic (PV) inverters tailored with reactive power management feature can support the grid voltage especially when the voltage fluctuates near its admissible limits. Although Q control allows reducing the grid voltage elevation along the distribution feeder, it brings extra...
Do wealth distributions follow power laws? Evidence from ‘rich lists’
Brzezinski, Michal
2014-07-01
We use data on the wealth of the richest persons taken from the 'rich lists' provided by business magazines like Forbes to verify if the upper tails of wealth distributions follow, as often claimed, a power-law behaviour. The data sets used cover the world's richest persons over 1996-2012, the richest Americans over 1988-2012, the richest Chinese over 2006-2012, and the richest Russians over 2004-2011. Using a recently introduced comprehensive empirical methodology for detecting power laws, which allows for testing the goodness of fit as well as for comparing the power-law model with rival distributions, we find that a power-law model is consistent with data only in 35% of the analysed data sets. Moreover, even if wealth data are consistent with the power-law model, they are usually also consistent with some rivals like the log-normal or stretched exponential distributions.
Optimal Sizing and Placement of Power-to-Gas Systems in Future Active Distribution Networks
DEFF Research Database (Denmark)
Diaz de Cerio Mendaza, Iker; Bhattarai, Bishnu Prasad; Kouzelis, Konstantinos;
2015-01-01
Power-to-Gas is recently attracting lots of interest as a new alternative for the regulation of renewable based power system. In cases, where the re-powering of old wind turbines threatens the normal operation of the local distribution network, this becomes especially relevant. However, the design...... the procedure employed to optimally size and allocate Power-to-Gas units in order to counteract the impact produced by the wind power repowering in medium-voltage networks. This approach employs the integer-valued particle swarm optimization technique with the purpose of minimizing both the number of units...... of medium voltage distribution networks does not normally follow a common pattern, finding a singular and very particular layouts in each case. This fact, makes the placement and dimensioning of such flexible loads a complicated task for the distribution system operator in the future. This paper describes...
A Survey on Control of Electric Power Distributed Generation Systems for Microgrid Applications
DEFF Research Database (Denmark)
Bouzid, Allal; Guerrero, Josep M.; Cheriti, Ahmed
2015-01-01
The introduction of microgrids in distribution networks based on power electronics facilitates the use of renewable energy resources, distributed generation (DG) and storage systems while improving the quality of electric power and reducing losses thus increasing the performance and reliability...... of the electrical system, opens new horizons for microgrid applications integrated into electrical power systems. The hierarchical control structure consists of primary, secondary, and tertiary levels for microgrids that mimic the behavior of the mains grid is reviewed. The main objective of this paper is to give...... a description of state of the art for the distributed power generation systems (DPGS) based on renewable energy and explores the power converter connected in parallel to the grid which are distinguished by their contribution to the formation of the grid voltage and frequency and are accordingly classified...
Reactive power balance in a distribution network with wind farms and CHPS
DEFF Research Database (Denmark)
Lund, Torsten; Nielsen, John Eli; Hylle, Per
2007-01-01
In Denmark, a large part of the electricity is generated by wind turbines and combined heat and power plants. Most of them are connected to the distribution systems. In periods with high wind speeds, large flows of reactive power have been observed between the 150kV and the 60 kV systems....... The transfer of reactive power reduces the capacity of the lines, causes thermal losses and can in some cases reduce the voltage stability margin of the system. To identify the origin of the problem, an actual distribution system with a high penetration of wind power and distributed generation has been...... thoroughly investigated. Active and reactive power measurements for transformers and production units have been inserted in a detailed system model. With intervals of 15 min and a total period of over 5 months, the measured situations have been reproduced with load flow calculations. The simulations have...
Voltage Control of Distribution Grids with Multi-Microgrids Using Reactive Power Management
Directory of Open Access Journals (Sweden)
WLODARCZYK, P.
2015-02-01
Full Text Available Low-voltage Microgrids can be valuable sources of ancillary services for the Distribution System Operators (DSOs. The aim of this paper was to study if and how multi-microgrids can contribute to Voltage Control (VC in medium-voltage distribution grids by means of reactive power generation and/or absorption. The hierarchical control strategy was proposed with the main focus on the tertiary control which was defined as optimal power flow problem. The interior-point algorithm was applied to optimise experimental benchmark grid with the presence of Distributed Energy Resources (DERs. Moreover, two primary objectives were formulated: active power losses and amount of reactive power used to reach the voltage profile. As a result the active power losses were minimised to the high extent achieving the savings around 22% during entire day.
Influence of laser power on atom probe tomographic analysis of boron distribution in silicon.
Tu, Y; Takamizawa, H; Han, B; Shimizu, Y; Inoue, K; Toyama, T; Yano, F; Nishida, A; Nagai, Y
2017-02-01
The relationship between the laser power and the three-dimensional distribution of boron (B) in silicon (Si) measured by laser-assisted atom probe tomography (APT) is investigated. The ultraviolet laser employed in this study has a fixed wavelength of 355nm. The measured distributions are almost uniform and homogeneous when using low laser power, while clear B accumulation at the low-index pole of single-crystalline Si and segregation along the grain boundaries in polycrystalline Si are observed when using high laser power (100pJ). These effects are thought to be caused by the surface migration of atoms, which is promoted by high laser power. Therefore, for ensuring a high-fidelity APT measurement of the B distribution in Si, high laser power is not recommended. Copyright © 2016 Elsevier B.V. All rights reserved.
This report is a generic verification protocol by which EPA’s Environmental Technology Verification program tests newly developed equipment for distributed generation of electric power, usually micro-turbine generators and internal combustion engine generators. The protocol will ...
Agent Services for Situation Aware Control of Power Systems With Distributed Generation
DEFF Research Database (Denmark)
Saleem, Arshad; Heussen, Kai; Lind, Morten
2009-01-01
Electric Power system of Denmark exhibits some unique characteristics. An increasing part of the electricity is produced by distributed generators (DGs). Most of these DGs are connected to the network at the distribution level. At the same time the concept of vehicle to grid (V2G) is already...... in the process of realization. This situation has created an incentive in electric power industry to utilize modern information and communication technologies (ICT) for improving the distribution system automation. This paper describes our work on how significantly increased amount of distributed generation...... could be exploited for the robust control of electric power systems. In particular, we present our work on the implementation of a dynamic service oriented system, in which autonomous agents represent different components of low voltage grid. These agents could offer and utilize electric power control...
Distributed AC power flow method for AC and AC-DC hybrid ...
African Journals Online (AJOL)
DR OKE
Present MGs incorporate AC and DC sources and loads along with storage and power ... Keywords: Microgrid (MG), Distributed Energy Resources (DER), Particle ... But in case of renewable based MGs, where small and intermittent sources ...
Distribution of a Certain Partition Function Modulo Powers of Primes
Institute of Scientific and Technical Information of China (English)
Hei-Chi CHAN
2011-01-01
In this paper, we study a certain partition function a(n) defined by Σn≥0 a(n)qn :=∏n=1(1-qn)-1(1-q2n)-1.We prove that given a positive integer j≥1 and a prime m≥5,there are infinitely many congruences of the type a(An + B)≡0 (mod mj). This work is inspired by Ono's ground breaking result in the study of the distribution of the partition function p(n).
Distributed power control algorithm based on game theory for wireless sensor networks
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Energy saving is the most important issue in research and development for wireless sensor networks. A power control mechanism can reduce the power consumption of the whole network.Because the character of wireless sensor networks is restrictive energy,this paper proposes a distributed power control algorithm based on game theory for wireless sensor networks which objects of which are reducing power consumption and decreasing overhead and increasing network lifetime.The game theory and OPNET simulation shows that the power control algorithm converges to a Nash Equilibrium when decisions are updated according to a better response dynamic.
Directory of Open Access Journals (Sweden)
Ganiyu A. Ajenikoko
2014-01-01
Full Text Available Reliability indices are parametric quantities used to assess the performance levels of electrical power distribution systems. In this work, a generalized quadratic model is developed for electrical power distribution system contributions to system reliability indices using Ikeja, Port-Harcourt, Kaduna and Kano distribution system feeders as case studies. The mean System Average Interruption Duration Index (SAIDI, System Average Interruption Frequency Index (SAIFI and Customer Average Interruption Duration Index (CAIDI contributions to system reliability indices for Ikeja, Port-Harcourt, Kaduna and Kano distribution systems were 0.0033, 0.0026, 0.0033 and 0.0018 respectively due to the fact that a prolonged period of interruptions was recorded on most of the feeders attached to Port-Harcourt and Kano distribution systems making them to be less reliable compared to Ikeja and Kaduna distribution systems. The generalized Quadratic model forms a basis for a good design, planning and maintenance of distribution systems at large.
Grid Monitoring and Advanced Control of Distributed Power Generation Systems
DEFF Research Database (Denmark)
Timbus, Adrian Vasile
. First part of the thesis investigates possible algorithms for fast and accurate identi cation of utility network variables such as voltage amplitude, frequency, phase angle and line impedance. Special attention has been paid to grid synchronization algorithm in terms of accurate estimation of grid...... of grid voltage and the frequency of utility network. As a result, fast and accurate identi cation of both variables has been achieved. In addition, positive and negative sequence components of grid voltage can also be calculated. Simple, yet powerful ltering techniques, based on second order generalized...... integrator (SOGI) and delay signal cancellation (DSC) have been used to separate the sequence components. Simulation and experimental results attest the accuracy and e ectiveness of the developed algorithms in identifying the frequency, phase angle and magnitude of grid voltages during severe distortions...
Asymptotic distribution of singular values of powers of random matrices
Alexeev, Nikita; Tikhomirov, Alexander
2010-01-01
Let $x$ be a complex random variable such that ${\\E {x}=0}$, ${\\E |x|^2=1}$, ${\\E |x|^{4} < \\infty}$. Let $x_{ij}$, $i,j \\in \\{1,2,...\\}$ be independet copies of $x$. Let ${\\Xb=(N^{-1/2}x_{ij})}$, $1\\leq i,j \\leq N$ be a random matrix. Writing $\\Xb^*$ for the adjoint matrix of $\\Xb$, consider the product $\\Xb^m{\\Xb^*}^m$ with some $m \\in \\{1,2,...\\}$. The matrix $\\Xb^m{\\Xb^*}^m$ is Hermitian positive semi-definite. Let $\\lambda_1,\\lambda_2,...,\\lambda_N$ be eigenvalues of $\\Xb^m{\\Xb^*}^m$ (or squared singular values of the matrix $\\Xb^m$). In this paper we find the asymptotic distribution function \\[ G^{(m)}(x)=\\lim_{N\\to\\infty}\\E{F_N^{(m)}(x)} \\] of the empirical distribution function \\[ {F_N^{(m)}(x)} = N^{-1} \\sum_{k=1}^N {\\mathbb{I}{\\{\\lambda_k \\leq x\\}}}, \\] where $\\mathbb{I} \\{A\\}$ stands for the indicator function of event $A$. The moments of $G^{(m)}$ satisfy \\[ M^{(m)}_p=\\int_{\\mathbb{R}}{x^p dG^{(m)}(x)}=\\frac{1}{mp+1}\\binom{mp+p}{p}. \\] In Free Probability Theory $M^{(m)}_p$ are known as Fuss--C...
Stationarity of the inter-event power-law distributions
2017-01-01
A number of human activities exhibit a bursty pattern, namely periods of very high activity that are followed by rest periods. Records of these processes generate time series of events whose inter-event times follow a probability distribution that displays a fat tail. The grounds for such phenomenon are not yet clearly understood. In the present work we use the freely available Wikipedia’s editing records to unravel some features of this phenomenon. We show that even though the probability to start editing is conditioned by the circadian 24 hour cycle, the conditional probability for the time interval between successive edits at a given time of the day is independent from the latter. We confirm our findings with the activity of posting on the social network Twitter. Our results suggest that there is an intrinsic humankind scheduling pattern: after overcoming the encumbrance of starting an activity, there is a robust distribution of new related actions, which does not depend on the time of day at which the activity started. PMID:28346480
Custom DC-DC converters for distributing power in SLHC trackers
Allongue, B; Blanchot, G; Faccio, F; Fuentes, C; Mattavelli, P; Michelis, S; Orlandis, S; Spiazzi, G
2008-01-01
A power distribution scheme based on the use of on-board DC-DC converters is proposed to efficiently distribute power to the on-detector electronics of SLHC trackers. A comparative analysis of different promising converter topologies is presented, leading to the choice of a magneticbased buck converter as a first conversion stage followed by an on-chip switched capacitors converter. An overall efficiency above 80% is estimated for the practical implementation proposed.
Error detection in core loading in the condition of asymmetrical distribution of power
Energy Technology Data Exchange (ETDEWEB)
Ryzhov, Andrei; Pinegin, Anatoly [National Research Centre ' Kurchatov Institute' , Moscow (Russian Federation)
2016-09-15
The error detection in core loading in many cases happens in conditions of a significant asymmetry in the distribution of power density, which is caused by thermal mechanical deformations of reactor core, and temperature differences in the cold legs of coolant. The asymmetry of power distribution essentially decreases the effectiveness of algorithms used to detect errors in the core loading using ICIS data. The paper proposes the ways for solving this problem by means of special filtration algorithms.
DEFF Research Database (Denmark)
Hu, Junjie; Yang, Guangya; Kok, Koen
2016-01-01
The increasing number of distributed energy resources connected to power systems raises operational challenges for the network operator, such as introducing grid congestion and voltage deviations in the distribution network level, as well as increasing balancing needs at the whole system level......, followed by a literature review and demonstration projects that apply to transactive control. Cases are then presented to illustrate the transactive control framework. At the end, discussions and research directions are presented, for applying transactive control to operating power systems, characterized...
Advanced Power Conversion and Distribution - Efficient Power for JPL Spacecraft Project
National Aeronautics and Space Administration — We will develop a power conversion solution that will increase end-to-end efficiency to 80% or more compared to the 30%-50% efficiency typically obtained through use...
Directory of Open Access Journals (Sweden)
Оksana G. Cherniukh
2015-06-01
Full Text Available The article presents the analysis of distribution of the group (according to AB0 system and rhesus characteristics (according to anti-D system in infants born to mothers with 0(I Rh(+ blood group in Chernivtsi region (Ukraine during the period of 2013-2014. The relationship of the umbilical bilirubin level and hemolytic disease of the newborn (HDN (erythroblastosis fetalis, the necessity of its careful monitoring during the first day of life of a newborn, especially in case a baby belongs to a certain risk group, has been analyzed. The issue concerning probable HDN occurrence from mothers with А(II Rh(+ blood group which is dominant in this region has been touched upon. The tasks for further work in this direction of ecopathophysiology in the areas of gene penetration have been assigned.
Zhao, Kai; Hui, Pan; Rao, Weixiong; Tarkoma, Sasu
2014-01-01
Human mobility has been empirically observed to exhibit Levy flight characteristics and behaviour with power-law distributed jump size. The fundamental mechanisms behind this behaviour has not yet been fully explained. In this paper, we analyze urban human mobility and we propose to explain the Levy walk behaviour observed in human mobility patterns by decomposing them into different classes according to the different transportation modes, such as Walk/Run, Bicycle, Train/Subway or Car/Taxi/Bus. Our analysis is based on two real-life GPS datasets containing approximately 10 and 20 million GPS samples with transportation mode information. We show that human mobility can be modelled as a mixture of different transportation modes, and that these single movement patterns can be approximated by a lognormal distribution rather than a power-law distribution. Then, we demonstrate that the mixture of the decomposed lognormal flight distributions associated with each modality is a power-law distribution, providing an e...
Agamy, Mohammed; Elasser, Ahmed; Sabate, Juan Antonio; Galbraith, Anthony William; Harfman Todorovic, Maja
2014-09-09
A distributed photovoltaic (PV) power plant includes a plurality of distributed dc-dc converters. The dc-dc converters are configured to switch in coordination with one another such that at least one dc-dc converter transfers power to a common dc-bus based upon the total system power available from one or more corresponding strings of PV modules. Due to the coordinated switching of the dc-dc converters, each dc-dc converter transferring power to the common dc-bus continues to operate within its optimal efficiency range as well as to optimize the maximum power point tracking in order to increase the energy yield of the PV power plant.
Influence of Mobile Users' Density Distribution on the CDMA Base Station Power
Lebl, Aleksandar; Mitić, Dragan; Popović, Miroslav; Markov, Žarko; Mileusnić, Mladen; Matić, Vladimir
2016-12-01
In this paper we analyze the influence of users' density distribution in one cell of CDMA mobile network (ie adjusted power control on the forward link) on base station emission power. This influence is analyzed for different circles radii around base station within which same emission power is generated for all mobile users, and for different values of propagation loss coefficient. It is proved that emission power in this cell must be increased comparing to the similar cell, which uses complete power control. The power increase is greater when greater number of users are situated near base station, and for greater values of propagation loss coefficient. The results are presented, illustrated by numerical examples and verified by simulation for three users' density distributions: uniform, decreasing and increasing density from the base station to the cell rim. The simulation process, which is based on random traffic process, is presented briefly.
Energy Technology Data Exchange (ETDEWEB)
Lingen Chen; Junlin Zheng; Fengrui Sun [Naval Univ. of Engineering, Faculty 306, Wuhan (China); Chih Wu [U.S. Naval Academy, Mechanical Engineering Dept., Annapolis, MD (United States)
2001-02-07
In this paper, the power density (defined as the ratio of the power output to the maximum specific volume in the cycle) is taken as the objective for performance optimisations of an endoreversible closed Brayton cycle coupled to constant-temperature heat reservoirs in the viewpoint of finite-time thermodynamics (FTT) or entropy generation minimisation (EGM). The optimum heat conductance distribution corresponding to the optimum power density of the hot- and cold-side heat exchangers for the fixed heat exchanger inventory is analysed using numerical examples. The influence of some design parameters on the optimum heat conductance distribution and the maximum power density and the optimum pressure ratio corresponding to the maximum power density are provided. The power plant design with optimisation leads to higher efficiency and smaller size. (Author)
Non-Gaussian velocity distributions - The effect on virial mass estimates of galaxy groups
Ribeiro, Andre L B; Trevisan, Marina
2011-01-01
We present a study of 9 galaxy groups with evidence for non-Gaussianity in their velocity distributions out to 4R200. This sample is taken from 57 groups selected from the 2PIGG catalog of galaxy groups. Statistical analysis indicates that non-Gaussian groups have masses significantly higher than Gaussian groups. We also have found that all non-Gaussian systems seem to be composed of multiple velocity modes. Besides, our results indicate that multimodal groups should be considered as a set of individual units with their own properties. In particular, we have found that the mass distribution of such units are similar to that of Gaussian groups. Our results reinforce the idea of non-Gaussian systems as complex structures in the phase space, likely corresponding to secondary infall aggregations at a stage before virialization. The understanding of these objects is relevant for cosmological studies using groups and clusters through the mass function evolution.
2011-05-11
... Employment and Training Administration Chrysler Group, LLC, Power Train Division, Mack Avenue Engine Plants 1... Group, LLC, Power Train Division, Mack Avenue Engine Plant 1, including on-site leased workers of... period at the Mack Avenue Engine Plant 2, Detroit, Michigan location of Chrysler Group, LLC, Power...
Reactive power balance in a distribution network with wind farms and CHPS
DEFF Research Database (Denmark)
Lund, Torsten; Nielsen, John Eli; Hylle, Per
2007-01-01
In Denmark, a large part of the electricity is generated by wind turbines and combined heat and power plants. Most of them are connected to the distribution systems. In periods with high wind speeds, large flows of reactive power have been observed between the 150kV and the 60 kV systems. The tra...
Electrical Power Transmission and Distribution Safety. Module SH-40. Safety and Health.
Center for Occupational Research and Development, Inc., Waco, TX.
This student module on electrical power transmission and distribution safety is one of 50 modules concerned with job safety and health. This module focuses on some of the general safety rules, techniques, and procedures that are essential in establishing a safe environment for the electrical power transmission worker. Following the introduction,…
Distributed Model Predictive Control for Active Power Control of Wind Farm
DEFF Research Database (Denmark)
Zhao, Haoran; Wu, Qiuwei; Rasmussen, Claus Nygaard;
2014-01-01
This paper presents the active power control of a wind farm using the Distributed Model Predictive Controller (D- MPC) via dual decomposition. Different from the conventional centralized wind farm control, multiple objectives such as power reference tracking performance and wind turbine load can......-scale wind farm control....
Distribution of deep water wave power around the Indian coast based on ship observations
Digital Repository Service at National Institute of Oceanography (India)
Chandramohan, P.; Nayak, B.U.; RamaRaju, V.S.
distribution of wave power in different directions over a year for each grid is presented. The annual mean wave power along the Indian coast varies from 11.4 to 15.2 KW per metre length of wave crest with a maximum of 15.2 KW for the regions off south Kerala...
Online Detection and Estimation of Grid Impedance Variation for Distributed Power Generation
DEFF Research Database (Denmark)
Jebali-Ben Ghorbal, Manel; Ghzaiel, Walid; Slama-Belkhodja, Ilhem;
2012-01-01
A better knowledge of the grid impedance is essential in order to improve power quality and control of the Distributed Power Generation Systems (DPGS) and also for a safe connection or reconnection to the utility grid. An LCL-filter associated to a Voltage Source Inverter (VSI) is usually used...
Analysis of the influences of grid-connected PV power system on distribution grids
Directory of Open Access Journals (Sweden)
Dumitru Popandron
2013-12-01
Full Text Available This paper presents the analysis of producing an electric power of 2.8 MW using a solar photovoltaic plant. The PV will be grid connected to the distribution network. The study is focused on the influences of connecting to the grid of a photovoltaic system, using modern software for analysis, modeling and simulation in power systems.
Heskes, P.J.M.
2011-01-01
Today’s Distributed Generators (DG) and load appliances are increasingly build up with power electronics. This trend is expected to grow further in the future. Also developments are ongoing to improve the performance and efficiency of grid components by means of power electronics and several grid co
DEFF Research Database (Denmark)
Luna, A.; Rocabert, J.; Candela, I.
2012-01-01
The Transmission System Operators are specially concerned about the Low Voltage Ride Through requirements of distributed generation power plants. Solutions based on the installation of STATCOMs and DVRs, as well as on advanced control functionalities for the existing power converters have contrib...... under such conditions. Its response will be analyzed with respect the synchronization needs that can be extracted from the standards....
Design Methodology of High Power Distributed Amplifier Employing Broadband Impedance Transformer
DEFF Research Database (Denmark)
Narendra, Kumar; Zhurbenko, Vitaliy; Collantes, Juan Mari;
2009-01-01
A novel topology of a high power distributed amplifier (DA) in combination with a broadband impedance transformer is presented. The advantages of the proposed topology are explored analytically and verified by a full-wave 3D simulations. Stability of the high power DA is verified with the pole...
Peak Clipping in Power Lines using Distributed Generation
Directory of Open Access Journals (Sweden)
S. Sambath
2015-05-01
Full Text Available This real time study is intent to analyze the impact and role of Distributed Generation (DG in Tamil Nadu, India to examine what the benefits of decentralized generation would be for peak clipping. Using load flow analysis to simulation over a quantify the loss reduction and system improvement by having decentralized generation available line conditions for actual rural feeders in Tamil Nadu, India. In order to realize the energy efficiency potential and upscale the implementation of DSM program by utility, load research should be the starting point. One of the key objectives of load research is to understand and analyze the utility’s system load profile and Peak clipping. This helps utilities to better plan their system in Demand side Management.
Calculated power distribution of a thermionic, beryllium oxide reflected, fast-spectrum reactor
Mayo, W.; Lantz, E.
1973-01-01
A procedure is developed and used to calculate the detailed power distribution in the fuel elements next to a beryllium oxide reflector of a fast-spectrum, thermionic reactor. The results of the calculations show that, although the average power density in these outer fuel elements is not far from the core average, the power density at the very edge of the fuel closest to the beryllium oxide is about 1.8 times the core avearge.
Impact of Distributed Wind on Bulk Power System Operations in ISO-NE (Presentation)
Energy Technology Data Exchange (ETDEWEB)
Brancucci Martinez-Anido, C.; Hodge, B. M.; Palchak, D.; Miettinen, J.
2014-11-01
The work presented in the paper corresponding to this presentation aims to study the impact of a range of penetration levels of distributed wind on the operation of the electric power system at the transmission level. This presentation is an overview of a case study on the power system in Independent System Operator New England. It is analyzed using PLEXOS, a commercial power system simulation tool
Meera, V.
2017-01-01
Multilevel inverter has been under research and development for more than three decades and has found successful industrial application. Also, it has become the enabling power conversion technology for high voltage and high power applications in present power systems and large electric motor drives. The propagated energy source consists of solar cells, wind turbines, micro-turbines (natural gas), fuel cells and storage batteries and also connected to the low voltage distribution network throu...
1983-01-01
Highlights of activities conducted during the reporting period to facilitate the exchange of technical information among scientists and engineers both within the federal government and within industry are cited. Interagency Advanced Power Group meetings and special efforts, project briefs, and organization development are considered.
Power of the muscular group's taekwondokas of the different qualification in steady-state mode.
Directory of Open Access Journals (Sweden)
Saienko Vladimir Grigor'evich
2011-11-01
Full Text Available Data are given meaningful totals display of force the muscle groups in athletes in the static mode. Displaying characteristics of muscle groups, hands (7, legs (5, trunk (2.The experiment involved 110 athletes (1-5 years experience training, age - 14-25 years old. Quantitative indicators, which reflect the individual level of informative power trained athletes. The optimum parameters of power qualities of athletes. Recommended use in training of special methods of strength training (isometric, concentric, eccentric, plyometric, isokinetic. In training must take into account the resistance, speed, joint angles, number of repetitions of the same approach.
A hydraulic distribution device of a powered support section
Energy Technology Data Exchange (ETDEWEB)
Zhuravlev, R.P.; Barinov, V.S.; Demidovich, Z.A.; Fedorov, L.I.; Kozhukhov, L.F.; Mosunov, Yu.Ya.
1981-01-30
The goal of this invention is to reduce the working time for manual control in the process of bracing a hydraulic prop and complete use of the working pressure of the support's hydraulic system to perform initial bracing of the hydraulic prop. To achieve this goal, the device has a reflux valve with a locking element and a choke, the latter situated between the piston and rod chambers; the floating piston is made with a stop which interacts with the motion limiter, while the rod of the floating piston has a pusher which interacts with the locking element of the reflux valve. Use of the hydraulic device of this design in powered supports during their operation under various mining conditions significantly raises the operating life of hydraulic supports and hydraulic distributors, while lowering the total complex's down time. Automatic positioning of the predetermined amount of initial spacing shortens the time in which the operator handles the support sections. The operator uses the time available to perform succeeding operations (transition to the next control panel, unloading, and transfer).
Power law distribution of seismic rates: theory and data
Saichev, A
2004-01-01
We report an empirical determination of the probability density functions P(r) of the number r of earthquakes in finite space-time windows for the California catalog, over fixed spatial boxes 5 x 5 km^2 and time intervals dt =1, 10, 100 and 1000 days. We find a stable power law tail P(r) ~ 1/r^{1+mu} with exponent mu \\approx 1.6 for all time intervals. These observations are explained by a simple stochastic branching process previously studied by many authors, the ETAS (epidemic-type aftershock sequence) model which assumes that each earthquake can trigger other earthquakes (``aftershocks''). An aftershock sequence results in this model from the cascade of aftershocks of each past earthquake. We develop the full theory in terms of generating functions for describing the space-time organization of earthquake sequences and develop several approximations to solve the equations. The calibration of the theory to the empirical observations shows that it is essential to augment the ETAS model by taking account of th...
Development of Power Supply System with Distributed Generators using Parallel Processing Method
Hirose, Kenichi; Takeda, Takashi; Okui, Yoshiaki; Yukita, Kazuto; Goto, Yasuyuki; Ichiyanagi, Katsuhiro; Matsumura, Toshiro
This paper describes a novel power system which consists of distributed energy resources (DER) with a static switch at the point of common coupling. Usage of the static switch with a parallel processing control is a new application of line interactive type uninterruptible power supply (UPS). In recent years, various ways of design, operation, and control methods have been studied in order to find more effective ways to utilize renewable energy and to reduce impact for environment. One of features of a proposed power system can interconnect to existing utility grid without interruption. Electrical power distribution to the loads by the power system can be continued between the states of interconnection and isolate operation seamlessly. The novel power system has other benefits such as more efficiency, demand site management, easy to control power system inside, improvement of reliability for power distribution, the minimum requirement of protection relays for grid interconnection. The proposed power system has been operated with the actual loads of 20kW in the campus of the Aichi Institute of Technology since 2007.
Internal Consistency and Power When Comparing Total Scores from Two Groups.
Barchard, Kimberly A; Brouwers, Vincent
2016-01-01
Researchers now know that when theoretical reliability increases, power can increase, decrease, or stay the same. However, no analytic research has examined the relationship of power to the most commonly used type of reliability-internal consistency-and the most commonly used measures of internal consistency, coefficient alpha and ICC(A,k). We examine the relationship between the power of independent samples t tests and internal consistency. We explicate the mathematical model upon which researchers usually calculate internal consistency, one in which total scores are calculated as the sum of observed scores on K measures. Using this model, we derive a new formula for effect size to show that power and internal consistency are influenced by many of the same parameters but not always in the same direction. Changing an experiment in one way (e.g., lengthening the measure) is likely to influence multiple parameters simultaneously; thus, there are no simple relationships between such changes and internal consistency or power. If researchers revise measures to increase internal consistency, this might not increase power. To increase power, researchers should increase sample size, select measures that assess areas where group differences are largest, and use more powerful statistical procedures (e.g., ANCOVA).
Energy Technology Data Exchange (ETDEWEB)
Touati, Said; Chennai, Salim; Souli, Aissa [Nuclear Research Centre of Birine, Ain Oussera, Djelfa Province (Algeria)
2015-07-01
The increased requirements on supervision, control, and performance in modern power systems make power quality monitoring a common practise for utilities. Large databases are created and automatic processing of the data is required for fast and effective use of the available information. Aim of the work presented in this paper is the development of tools for analysis of monitoring power quality data and in particular measurements of voltage and currents in various level of electrical power distribution. The study is extended to evaluate the reliability of the electrical system in nuclear plant. Power Quality is a measure of how well a system supports reliable operation of its loads. A power disturbance or event can involve voltage, current, or frequency. Power disturbances can originate in consumer power systems, consumer loads, or the utility. The effect of power quality problems is the loss power supply leading to severe damage to equipments. So, we try to track and improve system reliability. The assessment can be focused on the study of impact of short circuits on the system, harmonics distortion, power factor improvement and effects of transient disturbances on the Electrical System during motor starting and power system fault conditions. We focus also on the review of the Electrical System design against the Nuclear Directorate Safety Assessment principles, including those extended during the last Fukushima nuclear accident. The simplified configuration of the required system can be extended from this simple scheme. To achieve these studies, we have used a demo ETAP power station software for several simulations. (authors)
Allocation of Power Meters for Online Load Distribution Estimation in Smart Grids
DEFF Research Database (Denmark)
Kouzelis, Konstantinos; Diaz de Cerio Mendaza, Iker; Bak-Jensen, Birgitte
2015-01-01
observability of the load distribution in their grid throughout the day. This paper investigates the possibility of improving the observability by allocating a minimum number of additional online operated power meters in the distribution grid. This allocation, driven by optimisation, clustering, and forecasting...
DEFF Research Database (Denmark)
Rodriguez, Pedro; Luna, Alvaro; Hermoso, Juan Ramon
2011-01-01
The operation of distributed power generation systems under grid fault conditions is a key issue for the massive integration of renewable energy systems. Several studies have been conducted to improve the response of such distributed generation systems under voltage dips. In spite of being less s...
Control of power converters in distributed generation applications under grid fault conditions
DEFF Research Database (Denmark)
Rodriguez, Pedro; Luna, Alvaro; Munoz-Aguilar, Raul;
2011-01-01
The operation of distributed power generation systems under grid fault conditions is a key issue for the massive integration of renewable energy systems. Several studies have been conducted to improve the response of such distributed generation systems under voltage dips. In spite of being less s...
Coordinated Active Power Dispatch for a Microgrid via Distributed Lambda Iteration
DEFF Research Database (Denmark)
Hu, Jianqiang; Z. Q. Chen, Michael; Cao, Jinde
2017-01-01
A novel distributed optimal dispatch algorithm is proposed for coordinating the operation of multiple micro units in a microgrid, which has incorporated the distributed consensus algorithm in multi-agent systems and the -iteration optimization algorithm in economic dispatch of power systems. Spec...
Harmonic Domain Modeling of a Distribution System Using the DIgSILENT PowerFactory Software
DEFF Research Database (Denmark)
Wasilewski, J.; Wiechowski, Wojciech Tomasz; Bak, Claus Leth
The first part of this paper presents the comparison between two models of distribution system created in computer simulation software PowerFactory (PF). Model A is an exciting simplified equivalent model of the distribution system used by Transmission System Operator (TSO) Eltra for balenced loa...
Axial power distribution calculation using a neural network in the nuclear reactor core
Energy Technology Data Exchange (ETDEWEB)
Kim, Y. H.; Cha, K. H.; Lee, S. H. [Korea Electric Power Research Institute, Taejon (Korea, Republic of)
1997-12-31
This paper is concerned with an algorithm based on neural networks to calculate the axial power distribution using excore detector signals in the nuclear reactor core. The fundamental basis of the algorithm is that the detector response can be fairly accurately estimated using computational codes. In other words, the training set, which represents relationship between detector signals and axial power distributions, for the neural network can be obtained through calculations instead of measurements. Application of the new method to the Yonggwang nuclear power plant unit 3 (YGN-3) shows that it is superior to the current algorithm in place. 7 refs., 4 figs. (Author)
Feasibility Study of a 270V DC Flat Cable Aircraft Electrical Power Distribution System.
1982-01-01
POWER CABLE (27&A) 62 SPLICE ENVIRGNIMENT FIREWALL PENETRATION SPLICE I CU/2 C Fi gure 3.5.9.9 High, AmpacitY F/at Cable Replacemnt Harness InstallatiOn...NADC-82023-60 FEASIBILITY STUDY OF A.270V 0C FLAT CABLE AIRCRAFT ELECTRICAL POWER DISTRIBUTION SYSTEM SM.J. Musga R. J. Rinehart Boeing Aerospace Co...PERIOD COVEIRED FEASIBILITY STUDY OF A 270V DC FLAT CABLE Final Report AIRCRAFT ELECTRICAL POWER DISTRIBUTION SYSTEM 30 Dec. 1980 to Jan. 19824
Intragroup dark matter distribution in small galaxy group-like systems in a LCDM cosmology
Aceves, Hector; Altamirano-Devora, L; Ramon-Fox, F G; Cañas, R
2013-01-01
In this paper we study the distribution of dark matter in small galaxy groups, in a LCDM cosmology, identified using a physical criterion. We quantify the amount of intra-group dark matter and characterize its distribution. We find that compact associations of galaxies, as well as those intermediate and loose groups, have a rather flat profiles with a logarithmic slope of gamma =-0.2. Hence, the intra-group dark matter does not follow the same cuspy tendency that haloes of galaxies have. In intermediate and loose galaxy associations the intragroup matter tends to be <50% that of the total mass of the group, and in compact associations is <20% within their group radius. So, in general, common dark matter haloes of small galaxy groups are not cuspy nor massive.
An Iterative Power Allocation Algorithm for Group-wise Space-Time Block Coding Systems
Institute of Scientific and Technical Information of China (English)
ZHANG Hong-wei; ZHANG Hai-bin; SONG Wen-tao; LUO Han-wen; LIU Xing-zhao
2007-01-01
An iterative transmit power allocation (PA) algorithm was proposed for group-wise space-time block coding (G-STBC) systems with group-wise successive interference cancellation (GSIC) receivers.Group-wise interference suppression (GIS) filters are employed to separate each group's transmit signals from other interfer ences and noise.While the total power on all transmit symbols is constrained, all transmit PA coefficients are updated jointly according to the channel information at each iteration.Through PA, each detection symbol has the same post-detection signal to interference-and-noise ratio (SINR).The simulation results verify that the proposed PA algorithm converges at the equilibrium quickly after few iterations, and it achieves much lower bit error rates than the previous single symbol SIC PA and the fixed ratio PA algorithms for G-STBC systems with GSIC receivers.
Directory of Open Access Journals (Sweden)
Juliana P. de Castro
2006-01-01
Full Text Available Information about the distribution and insertion numbers of many transposable elements is restricted to few species of Drosophila, although these elements are widely distributed throughout the genus. The aim of this work was to describe the distribution and insertion numbers of four retrotransposons (copia, gypsy, micropia, I and four transposons (hobo, mariner, Minos and Bari-1 in the saltans group of Drosophila. Our data shows that, except for mariner, all the other elements are widespread within the saltans group and show variable insertion numbers of up to 24 copies.
Directory of Open Access Journals (Sweden)
Wang Hao
2016-01-01
Full Text Available In current communication network for distribution in Chinese power grid systems, the fiber communication backbone network for distribution and TD-LTE power private wireless backhaul network of power grid are both bearing by the SDH optical transmission network, which also carries the communication network of transformer substation and main electric. As the data traffic of the distribution communication and TD-LTE power private wireless network grow rapidly in recent years, it will have a big impact with the SDH network’s bearing capacity which is mainly used for main electric communication in high security level. This paper presents a fusion networking model which use a multiple-layer PTN network as the unified bearing of the TD-LTE power private wireless backhaul network and fiber communication backbone network for distribution. Network dataflow analysis shows that this model can greatly reduce the capacity pressure of the traditional SDH network as well as ensure the reliability of the transmission of the communication network for distribution and TD-LTE power private wireless network.
Review of Integration of Distributed Energy Resources (DERs) into Power Systems
DEFF Research Database (Denmark)
Wu, Qiuwei; Xu, Zhao
2011-01-01
of the integration of electric vehicles (EVs) to the DER integration concepts have been analyzed as well based on the energy storage potential of EVs. Two main concepts for DER integration, virtual power plant (VPP) and microgrids, are described and a comparison of the two concepts have been done. The comparison......An overview of the integration of distributed energy resources (DER) into power systems has been presented in this report. Different aspects of integration of DER into power systems have been reviewed and discussed which are listed below. needs of DER integration into power systems various...... state‐of‐the‐art DER integration concepts relations existing DER integration concepts to the EV system The power balancing challenges of power systems brought by high penetration of intermittent DER have been discussed, especially the wind power integration in the Danish context. The relevance...
Distributed Power Control Network and Green Building Test-Bed for Demand Response in Smart Grid
Sakaguchi, Kei; Nguyen, Van Ky; Tao, Yu; Tran, Gia Khanh; Araki, Kiyomichi
It is known that demand and supply power balancing is an essential method to operate power delivery system and prevent blackouts caused by power shortage. In this paper, we focus on the implementation of demand response strategy to save power during peak hours by using Smart Grid. It is obviously impractical with centralized power control network to realize the real-time control performance, where a single central controller measures the huge metering data and sends control command back to all customers. For that purpose, we propose a new architecture of hierarchical distributed power control network which is scalable regardless of the network size. The sub-controllers are introduced to partition the large system into smaller distributed clusters where low-latency local feedback power control loops are conducted to guarantee control stability. Furthermore, sub-controllers are stacked up in an hierarchical manner such that data are fed back layer-by-layer in the inbound while in the outbound control responses are decentralized in each local sub-controller for realizing the global objectives. Numerical simulations in a realistic scenario of up to 5000 consumers show the effectiveness of the proposed scheme to achieve a desired 10% peak power saving by using off-the-shelf wireless devices with IEEE802.15.4g standard. In addition, a small scale power control system for green building test-bed is implemented to demonstrate the potential use of the proposed scheme for power saving in real life.
Efficiency Analyses of a DC Residential Power Distribution System for the Modern Home
Directory of Open Access Journals (Sweden)
GELANI, H. E.
2015-02-01
Full Text Available The electric power system started as DC back in the nineteenth century. However, the DC paradigm was soon ousted by AC due to inability of DC to change its voltage level. Now, after many years, with the development of power electronic converters capable of stepping-up and down DC voltage and converting it to-and-from AC, DC appears to be challenging AC and attempting a comeback. We now have DC power generation by solar cells, fuel cells and wind farms, DC power transmission in the form of HVDC (High Voltage DC transmission, DC power utilization by various modern electronic loads and DC power distribution that maybe regarded as still in research phase. This paper is an attempt to investigate feasibility of DC in the distribution portion of electrical power system. Specifically, the efficiency of a DC distribution system for residential localities is determined while keeping in view the concept of daily load variation. The aim is to bring out a more practical value of system efficiency as the efficiencies of DC/DC converters making up the system vary with load variation. This paper presents the modeling and simulation of a DC distribution system and efficiency results for various scenarios are presented.