A new strategy of axial power distribution control based on three axial offsets concept
International Nuclear Information System (INIS)
We have proposed a very simple control procedure for axial xenon oscillation control based on a characteristic trajectory. The trajectory is drawn by three offsets of power distributions, namely, AOp, AOi and AOx. They are defined as the offset of axial power distribution, the offset of the power distribution under which the current iodine distribution is obtained as the equilibrium and that for xenon distribution, respectively. When these offsets are plotted on X-Y plane for (AOp-AOx, AOi-AOx) the trajectory draws a quite characteristic ellipse (or an elliptic spiral). On the other hands, Constant Axial Offset Control (CAOC) procedure is adopted as axial power distribution control strategy during both base load and load following operations in domestic PWRs. In the previous paper, we have presented an innovative procedure of axial power distribution control during load following in PWRs based on this trajectory such that the AOp-AOx is to be controlled to zero when the value deviates the pre-determined limiting values. In this paper we propose a modified control strategy to get more stability of axial power distributions. In this strategy, we control the trajectory to be close to the major axis of the ellipse when the power distribution reaches the limiting values. In other words, the plot is not controlled only to reduce AOp-AOx but also AOi-AOx is taken into account at the same time. It is known that when the plot is controlled to the major axis, it means that the point gives the peak position of axial xenon oscillation. Therefore xenon oscillation will not increase its amplitude any more. Thus more stable axial power distribution control is attained. This kind of design concept is quite important especially for the future PWRs with elongated fuel length and longer core life. Because in a longer effective core and also the longer core life, it has been known that the stability of axial xenon oscillation becomes more unstable. In this paper, some simulation
Average incore axial power distribution measurement by a multi excore detector
International Nuclear Information System (INIS)
French 1300 MWe reactors Protection System against DNB and excessive linear power is based on the average incore axial power distribution continuous measurement by multi-excore detectors. This paper describes the main results obtained during the first power escalation of PALUEL Unit 1 and 2, first units of 1300 MWe reactors and shows some INCORE/EXCORE power distribution comparisons. (author)
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)
International Nuclear Information System (INIS)
The presented paper is a preliminary step to evaluate the effect of radial and axial distribution of power generation on thermal analysis of whole fuel pin model with large L/D ratio. The model takes into account both radial and axial distribution of power generation due to power depression and core geometry, temperature and microstructure dependent on thermal conductivity. The microstructure distribution and the gap conductance for typical steady-state situation are given for the sensitivity analysis. The temperature and thermal conductivity distribution along the radial and axial directions obtained by different power distribution is used to indicate the sensitivity of power depression and power factor on thermal aspect. The evaluation is made for one step of incremental time and steady state approach is used. The analysis has been performed using a finite element-finite difference model. The result for typical reactor fuel shows that the sensitivity is too important to be omitted in thermal model
International Nuclear Information System (INIS)
Reactor core and fuel pin geometry of cylindrical pin arise heterogeneity of power generation along both axial and radial spaces. It influences the temperature and microstructures change distribution across the fuel and related properties. The present paper deal with sensitivity analyses of temperature and thermal property distribution by the axial and radial power distribution. A thermal model is developed for processing simulation using the given data. The analyses are performed using the model for power distribution effect on fuel properties and temperature distribution. The numerical result is resumed and presented. Qualitatively, the sensitivity is too important to be omitted in performance model. (author)
COLSS Axial Power Distribution Synthesis using Artificial Neural Network with Simulated Annealing
Energy Technology Data Exchange (ETDEWEB)
Shim, K. W.; Oh, D. Y.; Kim, D. S.; Choi, Y. J.; Park, Y. H. [KEPCO Nuclear Fuel Company, Inc., Daejeon (Korea, Republic of)
2015-05-15
The core operating limit supervisory system (COLSS) is an application program implemented into the plant monitoring system (PMS) of nuclear power plants (NPPs). COLSS aids the operator in maintaining plant operation within selected limiting conditions for operation (LCOs), such as the departure from nucleate boiling ratio (DNBR) margin and the linear heat rate (LHR) margin. In order to calculate above LCOs, the COLSS uses core averaged axial power distribution (APD). 40 nodes of APD is synthesized by using the 5-level in-core neutron flux detector signals based on the Fourier series method in the COLSS. We proposed the artificial neural network (ANN) with simulated annealing (SA) method instead of Fourier series method to synthesize the axial power distribution (APD) of COLSS. The proposed method is more accurate than the current method as the results of the axial shape RMS errors.
COLSS Axial Power Distribution Synthesis using Artificial Neural Network with Simulated Annealing
International Nuclear Information System (INIS)
The core operating limit supervisory system (COLSS) is an application program implemented into the plant monitoring system (PMS) of nuclear power plants (NPPs). COLSS aids the operator in maintaining plant operation within selected limiting conditions for operation (LCOs), such as the departure from nucleate boiling ratio (DNBR) margin and the linear heat rate (LHR) margin. In order to calculate above LCOs, the COLSS uses core averaged axial power distribution (APD). 40 nodes of APD is synthesized by using the 5-level in-core neutron flux detector signals based on the Fourier series method in the COLSS. We proposed the artificial neural network (ANN) with simulated annealing (SA) method instead of Fourier series method to synthesize the axial power distribution (APD) of COLSS. The proposed method is more accurate than the current method as the results of the axial shape RMS errors
Analysis on Fission Product Inventory with the Consideration of Axial Power Distribution
International Nuclear Information System (INIS)
Most of the regulatory guides have proposed taking the assumptions that can lead to more severe results than those that are realistically expected. In the case of a Loss of Coolant Accident (LOCA), the fission product inventory in the core is generally estimated based on the average burnup of a fuel assembly, regardless of the accident occurrence time and degree of fuel meltdown. However, the actual fuel burnup is non-uniform along the core height with axial power distributions, and fluctuated with fuel cycles as shown in. In this study, the variation of fission product inventory in the core is analyzed by considering the degree of fuel meltdown at the Beginning of Cycle (BOC), the Middle of Cycle (MOC), and the End of Cycle (EOC). For this study, the ORIGEN-ARP in the SCALE 6.1 package code system and the axial power distributions of the Ulchin (Hanul) unit 6 were used for the depletion calculation. The variation of fission product inventory in the core was analyzed based upon the degree of fuel meltdown, which reflects the axial power distribution of the fuel at BOC, MOC, and EOC. When considering some major fission products released into the containment, the calculation with the assumptions recommended by regulatory guides does not lead to results more conservative than for over approximately a 30% meltdown. Therefore, the fission products released into the containment need to be evaluated with a consideration of the accident occurrence point and the degree of fuel meltdown
International Nuclear Information System (INIS)
Procedures are described for maintaining the axial offset value of the core, as an indicia of the axial power distribution, substantially equal to a target value, which is modified periodically to account for core burnup. In one embodiment a neutron absorbing element within the core coolant, or moderator, is employed to assist control of reactivity changes associated with changes in power with the full length control rods mainly employed to adjust variations in the axial power distribution, while the part length rods remain completely withdrawn from the fuel region of the core. In a second embodiment reactivity changes associated with changes in power are controlled by the full length rods, while the part length rods are used to adjust the axial power distribution and the neutron absorbing element within the core coolant or moderator is used to compensate for xenon buildup or depletion. (author)
Uniform versus Nonuniform Axial Power Distribution in Rod Bundle CHF Experiments
Directory of Open Access Journals (Sweden)
Baowen Yang
2014-01-01
Full Text Available Rod bundle experiments with axially uniform and nonuniform heat fluxes are examined to explore the potential limitations of using uniform rod bundle CHF data for CHF correlation development of light water reactors with nonuniform axial power distribution (APD. The case of upstream burnout is presented as an example of unique phenomena associated with nonuniform rod bundle CHF experiments. It is a result from combined effect of axial nonuniform power shape and different interchannel mixing mechanisms. In addition, several key parameters are investigated with respect to their potential impacts on the thermal-hydraulic behaviors between rod bundles with uniform and nonuniform APDs. This type of misrepresentation cannot be amended or compensated through the use of correction factors due to the lack of critical information in the uniform rod bundle CHF testing as well as the fundamental difference in the underlining driving mechanisms. Other potential issues involved with the use of uniform rod bundle CHF data for nonuniform APD system applications also present strong evidence concerning the limitations and inadequacy of using uniform rod bundle CHF data for the correlation, prediction, and design limit calculation for safety analysis.
MCU calculation of spacing grid influence on fuel assembly axial power distribution
International Nuclear Information System (INIS)
Presence of spacing grid in fuel assembly noticeably decreases local energy release due to small local change of uranium-water ratio. Condition of total energy release conservation leads to some increase in maximum of axial power distribution. With MCU Monte Carlo code these increase/decrease were calculated for some VVER-440 and VVER-1000 F As. Since geometry of spacing grid is very complicated, two different sensibly simplified models were proposed. Both gave close results. Local minimums turn out to be ∼5% lower than average and local maximums increase slightly more than 1%. (Authors)
Axial power flow distributions of ultrasonic guided waves in viscous liquid-filled pipes
Institute of Scientific and Technical Information of China (English)
TA Dean
2004-01-01
The axial power flow (APF) magnitude and attenuation distributions of ultrasonic longitudinal guided waves in viscous liquid-filled elastic pipes are investigated. The optimal location, optimal mode and its frequency-thickness product (fd) for the test of pipes filled with viscous liquid are chosen according to APF and attenuation distributions. The results show that the APF magnitude distribution is an important parameter in choosing the modes and parameters. A particular mode has weak dispersion in ranges of fd values with large group velocity, while other modes with smaller group velocity in the same fd ranges have stronger dispersion. It has been observed that, within these ranges, the chosen mode has a larger APF on the pipe's wall. Therefore, in the region of fd values where a particular mode has a large group velocity, this mode will be effective to be used in testing elastic pipes filled with viscous liquid. The results obtained from both the APF analysis and attenuation distribution are consistent.
Improvement of the axial power distribution control capabilities in WWER-1000 reactors
International Nuclear Information System (INIS)
This article describes an automatic reactor power control system for WWER-1000 reactor and reports simulation analysis results for a typical daily load follow operation. The associated reactor control algorithm is called 'mode G' that uses a heavy-worth bank (H-bank) dedicated to axial power shape control and the light-gray banks (G-banks) for reactor power change and reactivity compensation. The simulation results for daily load follow operation in three burnup states of first cycle illustrate that the load follow capability of WWER-1000 reactors using this algorithm will be improved
International Nuclear Information System (INIS)
Measurements of relative power distributions were made using the γ-scanning method in the partially simulated cores of the axially heterogeneous FBR in order to study power flattening by introducing the inner blanket at core midplane and power distortion by insertion of simulated B4C control rod in the core. Power peaking factor was decreased by about 12 % in FCA XII-1 assembly in comparison with FCA XI-1 assembly, and the value was 1.11 +- 1.4 %. Distortion in power distribution caused by introducing the simulated B4C control rod in the FCA XII-1 assembly was obtained from the measured power distributions and propagation distance of the distortion was examined. It was observed that the inner blanket played a role to cease the propagation of distortion from the upper to lower half assembly. Calculations were made for all cores. Calculated results predict the measured results fairly well in the core region and inner blanket. A large descripancy remains in the outer blanket. (author)
International Nuclear Information System (INIS)
Presented here is a new numerical nodal method for the simulation of the axial power distribution within nuclear reactors using the one-dimensional one speed kinetics diffusion model with one group of delayed neutron precursors. Our method is based on a spectral analysis of the nodal kinetics equations. These equations are obtained by integrating the original kinetics equations separately over a time step and over a spatial node, and then considering flat approximations for the forward difference terms. These flat approximations are the only approximations that are considered in the method. As a result, the spectral nodal method for space - time reactor kinetics generates numerical solutions for space independent problems or for time independent problems that are completely free from truncation errors. We show numerical results to illustrate the method's accuracy for coarse mesh calculations. (author)
Effect of axial heat flux distribution on CHF
International Nuclear Information System (INIS)
Previous investigations for the effect of axial heat flux distributions on CHF and the prediction methods are reviewed and summarized. A total of 856 CHF data in a tube with a non-uniform axial heat flux distribution has been compiled from the articles and analyzed using the 1995 Groeneveld look-up table. The results showed that two representative correction factors, K5 of the look-up table and Tongs F factor, can be applied to describe the axial heat flux distribution effect on CHF. However, they overpredict slightly the measured CHF, depending on the quality and flux peak shape. Hence, a corrected K5 factor, which accounts for the axial heat flux distribution effect is suggested to correct these trends. It predicted the CHF power for the compiled data with an average error of 1.5% and a standard deviation of 10.3%, and also provides a reasonable prediction of CHF locations
Reactivity effects of nonuniform axial burnup distributions on spent fuel
International Nuclear Information System (INIS)
When conducting future criticality safety analyses on spent fuel shipping casks, burnup credit may play a significant role in determining the number of fuel assemblies that can be safely loaded into each cask. An important area in burnup credit analysis is the burnup variation along the length of the fuel assembly, which is determined by the location of the assembly in the reactor core and its residence time. A study of the effects of axial burnup distributions on reactivity has been conducted, using data from existing power plant fuel. Utilizing a one-dimensional, two-group diffusion code, named REALAX, the reactivity effects of axial burnup profiles have been calculated for various PWR fuel assemblies. The reactivity effects calculated by the code are defined in terms of k for the axially dependent burnup distribution minus k for a uniform axial burnup distribution at the assembly average burnup divided by k for a uniform axial burnup distribution at the assembly average burnup. Criticality safety specialists can take advantage of the quick-running code to determine axial effects of different assembly burnup profiles. In general, the positive reactivity effects of axial burnup distributions increase as burnup increases, though they do not increase faster than the overall decrease in reactivity due to burnup
Reactivity effects of nonuniform axial burnup distributions on spent fuel
Energy Technology Data Exchange (ETDEWEB)
Leary, R.W. II; Parish, T.A. [Texas A & M Univ., College Station, TX (United States)
1995-12-01
When conducting future criticality safety analyses on spent fuel shipping casks, burnup credit may play a significant role in determining the number of fuel assemblies that can be safely loaded into each cask. An important area in burnup credit analysis is the burnup variation along the length of the fuel assembly, which is determined by the location of the assembly in the reactor core and its residence time. A study of the effects of axial burnup distributions on reactivity has been conducted, using data from existing power plant fuel. Utilizing a one-dimensional, two-group diffusion code, named REALAX, the reactivity effects of axial burnup profiles have been calculated for various PWR fuel assemblies. The reactivity effects calculated by the code are defined in terms of k for the axially dependent burnup distribution minus k for a uniform axial burnup distribution at the assembly average burnup divided by k for a uniform axial burnup distribution at the assembly average burnup. Criticality safety specialists can take advantage of the quick-running code to determine axial effects of different assembly burnup profiles. In general, the positive reactivity effects of axial burnup distributions increase as burnup increases, though they do not increase faster than the overall decrease in reactivity due to burnup.
Axial power monitoring uncertainty in the Savannah River Reactors
International Nuclear Information System (INIS)
The results of this analysis quantified the uncertainty associated with monitoring the Axial Power Shape (APS) in the Savannah River Reactors. Thermocouples at each assembly flow exit map the radial power distribution and are the primary means of monitoring power in these reactors. The remaining uncertainty in power monitoring is associated with the relative axial power distribution. The APS is monitored by seven sensors that respond to power on each of nine vertical Axial Power Monitor (APM) rods. Computation of the APS uncertainty, for the reactor power limits analysis, started with a large database of APM rod measurements spanning several years of reactor operation. A computer algorithm was used to randomly select a sample of APSs which were input to a code. This code modeled the thermal-hydraulic performance of a single fuel assembly during a design basis Loss-of Coolant Accident. The assembly power limit at Onset of Significant Voiding was computed for each APS. The output was a distribution of expected assembly power limits that was adjusted to account for the biases caused by instrumentation error and by measuring 7 points rather than a continuous APS. Statistical analysis of the final assembly power limit distribution showed that reducing reactor power by approximately 3% was sufficient to account for APS variation. This data confirmed expectations that the assembly exit thermocouples provide all information needed for monitoring core power. The computational analysis results also quantified the contribution to power limits of the various uncertainties such as instrumentation error
The axial distribution of reactivity coefficients
International Nuclear Information System (INIS)
The purpose of the present work is to investigate the correlation of the axial distributions of the different reactivity coefficients with the neutron flux and the neutron flux squared. Calculations were carried out for the Zion Unit 2 PWR. Reactivity coefficients, forward fluxes and adjoint fluxes were all computed and correlations obtained. The core length was divided into 7 axial regions in order to obtain the effect on reactivity in the reactor as a whole of changing the cross sections in each axial region in turn. The parameters chosen for change were coolant density, coolant temperature and fuel temperature. The results appear to bear out our original hypothesis that the reactivity coefficient profiles have a higher positive correlation with the total flux squared profile than with the linear flux profile. (authors). 5 refs., 2 figs
Review of Axial Burnup Distribution Considerations for Burnup Credit Calculations
International Nuclear Information System (INIS)
This report attempts to summarize and consolidate the existing knowledge on axial burnup distribution issues that are important to burnup credit criticality safety calculations. Recently released Nuclear Regulatory Commission (NRC) staff guidance permits limited burnup credit, and thus, has prompted resolution of the axial burnup distribution issue. The reactivity difference between the neutron multiplication factor (keff) calculated with explicit representation of the axial burnup distribution and keff calculated assuming a uniform axial burnup is referred to as the ''end effect.'' This end effect is shown to be dependent on many factors, including the axial-burnup profile, total accumulated burnup, cooling time, initial enrichment, assembly design, and the isotopics considered (i.e., actinide-only or actinides plus fission products). Axial modeling studies, efforts related to the development of axial-profile databases, and the determination of bounding axial profiles are also discussed. Finally, areas that could benefit from further efforts are identified
Review of Axial Burnup Distribution Considerations for Burnup Credit Calculations
Energy Technology Data Exchange (ETDEWEB)
Wagner, J.C.; DeHart, M.D.
2000-03-01
This report attempts to summarize and consolidate the existing knowledge on axial burnup distribution issues that are important to burnup credit criticality safety calculations. Recently released Nuclear Regulatory Commission (NRC) staff guidance permits limited burnup credit, and thus, has prompted resolution of the axial burnup distribution issue. The reactivity difference between the neutron multiplication factor (keff) calculated with explicit representation of the axial burnup distribution and keff calculated assuming a uniform axial burnup is referred to as the ``end effect.'' This end effect is shown to be dependent on many factors, including the axial-burnup profile, total accumulated burnup, cooling time, initial enrichment, assembly design, and the isotopics considered (i.e., actinide-only or actinides plus fission products). Axial modeling studies, efforts related to the development of axial-profile databases, and the determination of bounding axial profiles are also discussed. Finally, areas that could benefit from further efforts are identified.
Investigation of axial power gradients near a control rod tip
International Nuclear Information System (INIS)
Highlights: → Pin power gradients near BWR control rod tips have been investigated. → A control rod tip is modeled in MCNP and compared to simplified 2D/3D geometry. → Small nodes increases pin power gradients; standard nodes underestimates gradients. → The MCNP results are validated against axial gamma scan of a controlled fuel pin. - Abstract: Control rod withdrawal in BWRs induces large power steps in the adjacent fuel assemblies. This paper investigates how well a 2D/3D method, e.g., CASMO5/SIMULATE5 computes axial pin power gradients adjacent to an asymmetrical control-rod tip in a BWR. The ability to predict pin power gradients accurately is important for safety considerations whereas large powers steps induced by control rod withdrawal can cause Pellet Cladding Interaction. The computation of axial pin power gradients axially around a control rod tip is a challenging task for any nodal code. On top of that, asymmetrical control rod handles are present in some BWR designs. The lattice code CASMO requires diagonal symmetry of all control rod parts. This introduces an error in computed pin power gradients that has been evaluated by Monte Carlo calculations. The results show that CASMO5/SIMULATE5, despite the asymmetrical control rod handle, is able to predict the axial pin power gradient within 1%/cm for axial nodal sizes of 15-3.68 cm. However, a nodal size of 3.68 cm still causes underestimations of pin power gradients compared with 1 cm nodes. Furthermore, if conventional node sizes are used, ∼15 cm, pin power gradients can be underestimated by over 50% compared with 1 cm nodes. The detailed axial pin power profiles from MCNP are corroborated by measured gamma scan data on fuel rods irradiated adjacent to control rods.
Measurement of the axial distribution of thermal neutron flux beside NRU loop fuel test sites
International Nuclear Information System (INIS)
At Chalk River Laboratories, fuel bundle tests for the CANDU power reactor fuel development program are performed in the fuel test sites of the NRU reactor loops. At present, calculated axial neutron flux profiles from neutronics modeling of the NRU reactor are used to distribute the total measured powers of the loop fuel test sites to determine the relative fuel bundle powers and burnups of the test bundles. In order to provide data for validating the calculated fluxes, measurements of the axial neutron flux distributions adjacent to the loop fuel test sites were also performed. This paper describes how the axial thermal neutron flux distributions were measured using in-core flux detectors and presents the results of comparisons between the measured fluxes and the calculated fluxes predicted by the neutronics simulation code. (author)
Lasnex Simulations of Axial Power Diagnostic for ZR
Morris, Heidi
2015-11-01
The dynamics of energy loss through diagnostic and/or laser entrance holes with or without shine shields is of inertial confinement fusion experiments envisioned for the National Ignition and ZR Facilities. 2-D radiation-hydrodynamic simulations using Lasnex for power diagnostic experiments using a secondary gold hohlraum fielded at the ZR facility are discussed. The axial radiation exiting the aperture of the dynamic hohlraum is modeled as time and spectrum-dependent 1-D and 2-D sources. Hohlraum energy balance and implications for the measured power are discussed.
Fehr, Ralph
2016-01-01
In this fully updated version of Industrial Power Distribution, the author addresses key areas of electric power distribution from an end-user perspective for both electrical engineers, as well as students who are training for a career in the electrical power engineering field. Industrial Power Distribution, Second Edition, begins by describing how industrial facilities are supplied from utility sources, which is supported with background information on the components of AC power, voltage drop calculations, and the sizing of conductors and transformers. Important concepts and discussions are featured throughout the book including those for sequence networks, ladder logic, motor application, fault calculations, and transformer connections. The book concludes with an introduction to power quality, how it affects industrial power systems, and an expansion of the concept of power factor, including a distortion term made necessary by the existence of harmonic.
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
International Nuclear Information System (INIS)
During load following operation of PWRs, it is required to control the changes of core power distribution and reactivity effectively. Since occurrence of xenon spatial distribution oscillation following the change of the reactor power can cause oscillation in the power distribution, one strategy for the core power distribution control is by eliminating xenon oscillation as fast as possible. A lot of studies have been done to solve the problem, some of which use complex mathematical treatments. On the other hand, the three axial offsets trajectory method, which uses a simple mathematical treatment based on two points reactor model, has been proved to be effective for xenon oscillation control. In this study, we examined the feasibility of application of the three axial offsets trajectory method as a strategy generator for the reactor control in the load following operation
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,
Axial flux distribution in a lattice position in the NRX reactor
International Nuclear Information System (INIS)
The axial thermal flux distribution in a lattice position in the NRX reactor has been measured at a number of moderator levels. The results have been fitted to sine functions and values are given for the positions of the flux maxima and the extrapolated flux lengths. Results of measurements of the axial fast flux distribution are also given. (author)
Axial distribution of absorbed doses in fast neutron field at the RB reactor
International Nuclear Information System (INIS)
The coupled fast thermal system CFTS at the RB reactor is created for obtaining fast neutron fields. The axial distribution of fast neutron flux density in its second configuration (CFTS-2) is measured. The axial distribution of absorbed doses is computed on the basis of mentioned experimental results. At the end these experimental and computed results are given. (Author)
Multilevel power distribution synthesis for a movable flux mapping system
International Nuclear Information System (INIS)
A Computer Software package has been developed to support the synthesis of the 3-dimensional power distribution from detector signals from a movable flux mapping system. The power distribution synthesis is based on methodology developed for fixed incore detectors. The full core solution effectively couples all assemblies in the core whether they are instrumented or not. The solution is not subject to approximations for the treatment of assemblies where a measurement cannot be made and provides an accurate representation of axial variations which may be induced by axial blankets, burnable absorber cut back regions and axially zoned flux suppression rods
Energy Technology Data Exchange (ETDEWEB)
Sorrells, M.A.
1990-01-01
This paper is a broad overview of industrial power distribution. Primary focus will be on selection of the various low voltage components to achieve the end product. Emphasis will be on the use of national standards to ensure a safe and well designed installation.
Intraocular lens power calculation in eyes with short axial length
Directory of Open Access Journals (Sweden)
Marilita M Moschos
2014-01-01
Full Text Available Aim: To evaluate and compare the predictive capacity of four intraocular lens (IOL power calculation formulas (SRK/T, Hoffer Q, Holladay 1, and Haigis in eyes shorter than 22.0 mm. Setting and Design: Observational study. Materials and Methods: Participants in our study were 69 consecutive patients with a preoperative axial length (AL of less than 22.0 mm in one or both eyes. All patients underwent phacoemulsification with IOL implantation and postoperative target of refraction was analyzed. Specifically, the differences in the mean absolute estimation error (AE for the four formulas were analyzed. Furthermore, the percentage of eyes with AE within ±0.5 and ±1.0 D for each formula was estimated, as well as the correlation coefficient (r between the AL and estimation error (E for each formula. The Mann-Whitney U test was used to compare differences in the AEs of the formulas. A statistically significant difference was defined as P < 0.05. Results: The Haigis formula had statistically significant smaller mean AE in comparison to Holladay 1, Hoffer Q, and SRK/T. The Haigis formula predicted more eyes with E within ±0.5 and ±1.0 D of predicted spherical equivalent compared to other formulas. Correlation between AL and AE revealed a negative r value and P < 0.05 for all formulas. Conclusions: Haigis formula provides more accurate results concerning the postoperative target of refraction in eyes with AL less than 22.0 mm. Hoffer Q could be also used as an alternative.
Electric power distribution reliability
Brown, Richard E
2002-01-01
Balancing theory, practical knowledge, and real-world applications, this reference consolidates all pertinent topics related to power distribution reliability into one comprehensive volume. Exploring pressing issues in creating and analyzing reliability models, the author highlights the most effective techniques to achieve maximum performance at lowest cost. With over 300 tables, figures, and equations, the book discusses service interruptions caused by equipment malfunction, animals, trees, severe weather, natural disasters, and human error and evaluates strategies to improve reliability and
Effects of axial burnup distributions on the reactivity of spent fuel
International Nuclear Information System (INIS)
Criticality safety analyses for spent fuel shipping casks will eventually need to take credit for the decreased reactivity of spent fuel assemblies resulting from burnup. In order to do so, it will be necessary to assess the reactivity effects of the multitude of burnup shapes that can characterize spent fuel. A computer program, CASAX, has been written that allows the analyst to quickly evaluate the reactivity effects of actual and simplified axial burnup distributions on a group of PWR fuel assemblies. CASAX employs one dimensional, two group diffusion calculations to determine the k-effective of a cluster of assemblies. Assembly average, burnup dependent, two group cross sections for CASAX were obtained from CASMO3 using physical properties representative of Westinghouse 17 x 17 assemblies. Reactivity results are presented in terms of (k for the axially dependent burnup distribution minus k for a uniform axial burnup distribution at the assembly average burnup)/(k for a uniform axial burnup distribution at the assembly average burnup). Axial burnup distributions can have both positive and negative effects on the calculated k-effective. Positive reactivity effects generally result at high assembly average burnups and for axial distributions with low burnups in the assembly's tips
Power distribution measuring device
International Nuclear Information System (INIS)
The present invention concerns a device for measuring power distribution of neutrons in a nuclear reactor. That is, a gamma thermometer used so far has drawbacks of slow time response and low sensitivity although it is not always necessary to use a movable incore detector for calibration. However, the device of the present invention compensates the drawback by incorporating a gamma thermometer and an another incore detector of a different type in an identical detector assembly. The gamma thermometer is calibrated by an electric heater. With such a constitution, the sensitivity calibration of the detector of different type incorporated in the identical detector assembly can be conducted without relying on a movable detector when the reactor is stable. Further, if the detector of the different type having rapid response, such as a fission ionization chamber or a self-powered type detector is used as a detector, a reactor core power distribution monitoring system of rapid time response can be attained. (I.S.)
Torki, Mohammad Ebrahim; Kazemi, Mohammad Taghi; Reddy, Junuthula N.; Haddadpoud, Hassan; Mahmoudkhani, Saeid
2014-02-01
In this paper, flutter of functionally graded material (FGM) cylindrical shells under distributed axial follower forces is addressed. The first-order shear deformation theory is used to model the shell, and the material properties are assumed to be graded in the thickness direction according to a power law distribution using the properties of two base material phases. The solution is obtained by using the extended Galerkin's method, which accounts for the natural boundary conditions that are not satisfied by the assumed displacement functions. The effect of changing the concentrated (Beck's) follower force into the uniform (Leipholz's) and linear (Hauger's) distributed follower loads on the critical circumferential mode number and the minimum flutter load is investigated. As expected, the flutter load increases as the follower force changes from the so-called Beck's load into the so-called Leipholz's and Hauger's loadings. The increased flutter load was calculated for homogeneous shell with different mechanical properties, and it was found that the difference in elasticity moduli bears the most significant effect on the flutter load increase in short, thick shells. Also, for an FGM shell, the increase in the flutter load was calculated directly, and it was found that it can be derived from the simple power law when the corresponding increase for the two base phases are known.
Addressing the Axial Burnup Distribution in PWR Burnup Credit Criticality Safety
International Nuclear Information System (INIS)
This paper summarizes efforts related to developing a technically justifiable approach for addressing the axial burnup distribution in PWR burnup-credit criticality safety analyses. The paper reviews available data on the axial variation in burnup and the effect of axial burnup profiles on reactivity in a SNF cask. A publicly available database of profiles is examined to identify profiles that maximize the neutron multiplication factor, keff, assess its adequacy for general PWR burnup credit analyses, and investigate the existence of trends with fuel type and/or reactor operations. For this assessment, a statistical evaluation of the keff values associated with the profiles in the axial burnup profile database was performed that identifies the most reactive profiles as statistical outliers that are not representative of typical discharged SNF assemblies. The impact of these bounding profiles on the neutron multiplication factor for a high-density burnup credit cask is quantified. Finally, analyses are presented to quantify the potential reactivity consequence of assemblies with axial profiles that are not bounded by the existing database. The paper concludes with findings for addressing the axial burnup distribution in burnup credit analyses
Effect of void dependent reactivity modeling bias on BWR axial power tilt - 256
International Nuclear Information System (INIS)
Inspired by a Pennsylvania State University study reported in the PHYSOR08 conference related to BWR axial power tilt, an investigation is made as to if there could be any intrinsic deficiency in the conventional nodal diffusion theory leading to a tilt in BWR axial power prediction. It is found that the two-group nodal diffusion theory itself does not cause axial power tilt compared to multigroup deterministic 3D transport calculation. However, the usual practice of flat source approximation in 2D lattice codes based on the Collision Probability (CP) method or the Method of Characteristics (MOC) can cause a void dependent reactivity bias when used to generate the node homogenized cross-sections, if the same geometry meshing modeling is used for all the axial sections over which the void fraction varies severely. The reactivity bias can be removed by using lattice code models based on SN method or MOC method with linear instead of flat source approximation. In absence of the void dependent reactivity bias, there is no axial power tilt between two-group nodal diffusion calculation and multi-group deterministic 3D transport calculation. Therefore there is no intrinsic deficiency in the nodal diffusion theory that causes BWR axial power tilt. But one has to be careful with using the flat source approximation and the generic-meshing modeling in generating homogenized nodal diffusion cross-sections for high void cases. As for any possible axial power tilt between multi-group deterministic 3D transport calculation and continuous energy Monte Carlo 3D simulation, that would be a different issue. (authors)
End effect analysis with various axial burnup distributions in high density spent fuel storage racks
International Nuclear Information System (INIS)
Highlights: • Criticality tests are carried out with various axial burnup distributions of fuel assemblies for spent fuel storage racks. • KENO-Va code system was used to obtain criticalities with 10 axial segments. • ORIGEN-S code system was used to obtain burnup dependent axial compositions. • The criticality and burnup dependent reactivity difference are obtained from the results. • End effect quantifications are satisfactory confirming the previous suggestions. - Abstract: End effect of spent fuel comes from the difference between uniform and actual axial burnup distributions of fuel assemblies. It is significant to control the criticality safety in spent fuel storage and transportation. This work is focused on estimation of end effect in the spent fuel of light water reactor for the spent fuel storage rack region-II. High and low burnups of corresponding different uranium enrichments are taken into consideration to analyze the end effect with different axial burnup distributions such as uniform, MOC and EOC profiles. Two types of fuel assemblies such as CE type and Westinghouse type are considered. The whole calculations have been carried out by using the SCALE6 code including ORIGEN-S and KENO-Va
Flow induced noise calculations for non-axially distributed hydrophones in towed arrays
Institute of Scientific and Technical Information of China (English)
WANG Bin; TANG Weilin; FAN Jun
2009-01-01
Two improvements are put forward on the analyses of flow induced noise in towed arrays. First, the differences between Corcos/Carpenter pressure fluctuation models have been discussed at length, as well as flow induced noise calculated with these two models. Second, flow induced noise received by the finite hydrophones distributed non-axially is discussed and the relevant power spectrum is deduced. The results show that there are some disparities between the wavenumber spectrums and the responses of flow induced noise of these two models. Flow induced noise is closely related with the tow speed, the tube radius and the off-axis distance. The numerical analyses with Carpenter model indicate that the power spectrum of flow induced noise will increase 24 dB approximately with the tow speed doubled, decrease with the radius of the tube, and increase with the off-axis distance. The tube radius and the off-axis distance have greater influence on the high-frequency components than on the low-frequency components.
Energy loss distributions of 7 TeV protons axially channeled in the bent Si crystal
Stojanov, Nace; Petrović, Srdjan
2016-04-01
In this article, the energy loss distributions of relativistic protons axially channeled in the bent Si crystal are studied. The crystal thickness is equal to 1 mm, which corresponds to the reduced crystal thickness, Λ, equal to 1.22, whereas the bending angle, α, was varied from 0 to 30 μrad. The proton energy of 7 TeV was chosen in accordance with the concept of using the bent crystals as a tool for selective deflection of the beam halo particles from the LUA9 experiment at LHC. For the continuum interaction potential of the proton and the crystal the Molière's expression was used and the energy loss of a proton was calculated by applying the trajectory dependent stopping power model. Further, the uncertainness of the scattering angle of the proton caused by its collisions with the electrons of the crystal and the divergence of the proton beam were taken into account. The energy loss distribution of the channeled protons was obtained via the numerical solution of the proton equations of motion in the transverse plane and the computer simulation method. The analysis of the obtained theoretical data shows that the shape of the energy loss distribution strongly depends on the horizontal or vertical direction of the curvature of the crystal. The number of dechanneled protons as a function of the bending angle also strongly depends on the direction of the crystal's curvature. As a result, the dechanneling rates and ranges, obtained from the Gompertz type sigmoidal fitting functions, have different sets of values for different bending orientations. We have also studied the influence of the proton beam divergence on the energy loss distribution of channeled protons.
A simplified calculation of the axial distribution temperature in a medium channel of PWR
International Nuclear Information System (INIS)
A subroutine for the calculations of the axial distribution temperature of a Pressurized Water Reactor coolant was developed. The values of water specific heat in function of the temperature were adjusted by the least square method which allows the explicit determination of the temperature field. (E.G.)
Axial ion charge state distribution in the vacuum arc plasma jet
International Nuclear Information System (INIS)
We report on our experimental studies of the ion charge state distribution (CSD) of vacuum arc plasmas using a time-of-flight diagnostic method. The dependence of the CSD on the axial distance from the plasma source region was measured for a titanium vacuum arc. It was found that the axial CSD profile is nonuniform. Generally, the mean charge state increases approximately linearly with axial distance from about 1.7 at 12 cm up to 1.9 at 25 cm from the plasma source. A model for ion transport in the free boundary plasma jet is proposed which is based on the existence of an electric field in the quasineutral plasma. This model qualitatively explains the experimental results. (c) 2000 American Institute of Physics
Sensitivity studies for 3-D rod ejection analyses on axial power shape
Energy Technology Data Exchange (ETDEWEB)
Park, Min-Ho; Park, Jin-Woo; Park, Guen-Tae; Ryu, Seok-Hee; Um, Kil-Sup; Lee, Jae-Il [KEPCO NF, Daejeon (Korea, Republic of)
2015-10-15
The current safety analysis methodology using the point kinetics model combined with numerous conservative assumptions result in unrealistic prediction of the transient behavior wasting huge margin for safety analyses while the safety regulation criteria for the reactivity initiated accident are going strict. To deal with this, KNF is developing a 3-D rod ejection analysis methodology using the multi-dimensional code coupling system CHASER. The CHASER system couples three-dimensional core neutron kinetics code ASTRA, sub-channel analysis code THALES, and fuel performance analysis code FROST using message passing interface (MPI). A sensitivity study for 3-D rod ejection analysis on axial power shape (APS) is carried out to survey the tendency of safety parameters by power distributions and to build up a realistic safety analysis methodology while maintaining conservatism. The currently developing 3-D rod ejection analysis methodology using the multi-dimensional core transient analysis code system, CHASER was shown to reasonably reflect the conservative assumptions by tuning up kinetic parameters.
Fork, Richard L.
2001-01-01
The objective was to assess the feasibility of safely collecting solar power at geostationary orbit and delivering it to earth. A strategy which could harness a small fraction of the millions of gigawatts of sunlight passing near earth could adequately supply the power needs of earth and those of space exploration far into the future. Light collected and enhanced both spatially and temporally in space and beamed to earth provides probably the only practical means of safe and efficient delivery of this space solar power to earth. In particular, we analyzed the feasibility of delivering power to sites on earth at a comparable intensity, after conversion to a usable form, to existing power needs. Two major obstacles in the delivery of space solar power to earth are safety and the development of a source suitable for space. We focused our approach on: (1) identifying system requirements and designing a strategy satisfying current eye and skin safety requirements; and (2) identifying a concept for a potential space-based source for producing the enhanced light.
Distribution of Cathode Spots in Vacuum Arc Under Nonuniform Axial Magnetic Fields
Institute of Scientific and Technical Information of China (English)
SHI Zong-qian; JIA Shen-li; WANG Li-jun; LI Xing-wen; WANG Zheng
2007-01-01
Recent results on the distribution of vacuum arc cathode spots (CSs) in nonuniform axial magnetic field (AMF) are presented.Based on previous studies,we deem that two contrary influences of AMF,inward effect and outward effect,are attributed to CSs distribution.With this notion,we have analyzed the controlling effectiveness of nonuniform AMF on CSs distribution. Experiments were conducted in a detachable vacuum chamber with iron-style AMF electrodes.Images of vacuum arc column and the distribution of CSs were photographed with a high-speed charge coupled device (CCD) camera. Experimental results agreed well with the theoretical analysis.
Optimal axial enrichment distribution of the boiling water reactor fuel under the Haling strategy
International Nuclear Information System (INIS)
The axial enrichment distribution of boiling water reactor fuel is optimized to improve uranium utilization subject to constraints on thermal margins. It is assumed that the reactor is operated under the Haling strategy, so that determination of the enrichment distribution can be decoupled from the poison management. This nonlinear optimization problem is solved using a method of approximation programming, where each iteration step is formulated in terms of linear goal programming to handle infeasible problems. The core is represented by an axial one-dimensional model. The average enrichment of a two-region fuel can be slightly reduced by increasing the enrichment of the lower half rather than the upper half. The optimal solutions for a 24-region fuel, in which the enrichments of indivdual nodes can differ from one another, display double-humped enrichment distributions. The natural uranium blanket design is also investigated, and it is concluded that blanketed fuel is practically optimal using the Haling strategy
Vibrational power flow of a finite cylindrical shell with discrete axial stiffeners
Institute of Scientific and Technical Information of China (English)
LIU Yanmei; HUANG Xieqing
2002-01-01
The structural wave power flows in an elastic finite cylindrical shell with discrete axial stiffeners are studied when a simple harmonic force is applied on it. The equations of motion of the shell are derived by using Flugge equation and Hamilton variational principle,and the responses of the shell are obtained. By use of the basic definition of the power flow, the characteristics of axial propagation of the power flow supplied by input structure and carried by different shell internal forces of a forced shell are investigated. The effects of parameters, such as relative location of driving force and stringer, driving force type and structural damping on the vibrational power flows in the shell, are discussed. These provide some theoretical bases for vibration control and noise reduction of this kind of structure.
Červenka, Milan; Bednařík, Michal
2015-10-01
This work verifies the idea that in principle it is possible to reconstruct axial temperature distribution of fluid employing reflection or transmission of acoustic waves. It is assumed that the fluid is dissipationless and its density and speed of sound vary along the wave propagation direction because of the fluid temperature distribution. A numerical algorithm is proposed allowing for calculation of the temperature distribution on the basis of known frequency characteristics of reflection coefficient modulus. Functionality of the algorithm is illustrated on a few examples, its properties are discussed. PMID:26520344
Inter platform power distribution
International Nuclear Information System (INIS)
In today's world of high operating costs and low oil prices new methods of construction are needed to ensure economic viability. One such was is to maximize the use of an existing infrastructure. Marathon utilized power generated on Brae A and Brae B to supply the requirements of East Brae using transfer by 33kV sub-sea cable. First oil was produced in December 1993. This resulted in platform weight savings of around 3,000 tonnes, with cost savings in excess of Brit-pounds 60 million
Research on axial total pressure distributions of sonic steam jet in subcooled water
International Nuclear Information System (INIS)
The axial total pressure distributions of sonic steam jet in subcooled water were experimentally investigated for three different nozzle diameters (6.0 mm, 8.0 mm and 10.0 mm). The inlet steam pressure, and pool subcooling subcooled water temperature were in the range of 0.2-0.6 MPa and 420-860 ℃, respectively. The effect of steam pressure, subcooling water temperature and nozzle size on the axial pressure distributions were obtained, and also the characteristics of the maximum pressure and its position were studied. The results indicated that the characteristics of the maximum pressure were influenced by the nozzle size for low steam pressure, but the influence could be ignored for high steam pressure. Moreover, a correlation was given to correlate the position of the maximum pressure based on steam pressure and subcooling water temperature, and the discrepancies of predictions and experiments are within ±15%. (authors)
International Nuclear Information System (INIS)
The microscopic model for two-dimensional distribution function P(σ,η) for quadrupolar glass freezing of axial (σ) and eccentric (η) order parameters in solid hydrogen is considered within the Sherrington-Kirkpatrick mean-field approach. Assuming the exchange interactions between axial and eccentric quadrupoles to be independent Gaussian random variables with variance J2/N and K2/N, respectively (with N being the number of lattice sites), we derived a set of self-consistent equations for quadrupolar order parameters and the corresponding local susceptibilities. While for J≠K the axial quadrupolar order parameter is nonvanishing in the high-temperature phase due to broken local symmetry and the corresponding quadrupolar susceptibility exhibits smeared-out behavior, the eccentric order parameter becomes zero at well-defined critical temperature depending on the ratio K/J. Furthermore, the properties of the P(σ,η) distribution function are investigated by introducing a single effective order parameter σeff (1eff<0) directly related to the second frequency moment of the nuclear magnetic resonance line shapes. Comparison of the present microscopic theory with earlier phenomenological approaches to the problem is also made
Bending vibration of axially loaded Timoshenko beams with locally distributed Kelvin-Voigt damping
Chen, Wei-Ren
2011-06-01
Utilizing the Timoshenko beam theory and applying Hamilton's principle, the bending vibration equations of an axially loaded beam with locally distributed internal damping of the Kelvin-Voigt type are established. The partial differential equations of motion are then discretized into linear second-order ordinary differential equations based on a finite element method. A quadratic eigenvalue problem of a damped system is formed to determine the eigenfrequencies of the damped beams. The effects of the internal damping, sizes and locations of damped segment, axial load and restraint types on the damping and oscillating parts of the damped natural frequency are investigated. It is believed that the present study is valuable for better understanding the influence of various parameters of the damped beam on its vibration characteristics.
International Nuclear Information System (INIS)
We have studied the angular distributions for 6--30-MeV Cq+ (q=4--6) and 2--9-MeV H+ ions axially channeled in the [001] direction of a thin silicon crystal (1792 and 1900 A). We report highly structured two-dimensional angular distributions that depend sensitively on the projectile's velocity and incident charge state and the target's thickness and azimuthal orientation. Some structure in the angular contour maps is the result of a rainbow effect in axial channeling (i.e., extrema in the classical deflection function). State-to-state charge-state distributions, which are required to interpret the data accurately, have also been measured. All measured angular distributions have been explained via Monte Carlo trajectory calculations using Moliere's approximation to the Thomas-Fermi screening function and a screening length given by target electrons alone. The calculations indicate that all projectile velocity and charge-state effects and the target-thickness effects observed are the result of the projectile's transverse oscillatory motion in the channel. Using this information, we show that swift heavy-ion and proton angular distributions are simply related using a scaling law that depends only on the projectile's velocity and charge-to-mass ratio and on the crystal thickness
Potential of power recovery of a subsonic axial fan in windmilling operation
Courty Audren, Suk Kee; Binder, Nicolas; Carbonneau, Xavier; Challas, Florent
2013-01-01
During the last decades, efforts to find efficient green energy solutions have been widely increased in response to environmental concerns. Among all renewable energies, this paper is focused on wind power generation. To this end, a windmilling axial fan in turbine operation is experimentally and numerically investigated. Under specific conditions, the studied fan is naturally freewheeling. Consequently, the main objective of this analysis is to determine whether or not this intrinsic windmil...
The effect of axial fuel rod power profile on fuel temperature and cladding strain
Directory of Open Access Journals (Sweden)
Kim Kyu-Tae
2010-01-01
Full Text Available The most limiting design criteria for nuclear reactor normal operating conditions (ANS Condition I are known to be rod internal pressure and cladding oxidation, while those for nuclear reactor transient operating conditions (ANS Conditon II to be fuel centerline temperature and transient cladding total tensile strain. However, the design margins against fuel temperature and transient cladding tensile strain become smaller since power uprating is being or will be utilized for the most of nuclear power reactors to enhance the economics of nuclear power. In order to secure sufficient design margins against fuel temperature and cladding total tensile strain even for power uprating, the current axial rod power profiles used in the reactor transient analysis were optimized to reduce over-conservatism, considering that 118% overpower of a steady-state peak rod average power was not exceeded during the reactor transients. The comparison of the current axial rod power profiles and the optimized ones indicates that the latter reduces the fuel centerline temperature and cladding total tensile strain by 26°C and 0.02%, respectively.
POWER DISTRIBUTION NETWORKS GRAPH OPTIMIZATION
Dorin Sarchiz; Vasile Dub
2009-01-01
The goal of our paper is to present a mathematical model for the power grids graph optimization by one robustness approach of grids safety. The power networks, particularly the electric grids are vulnerable against events like natural disasters, intentioned attacks on several distributed elements of the grid: thus, the risk management of large grids must include procedures on measuring, analyzing and modifying the existent systems to be able to possess one appropriate robustness.
Power Generation and Distribution via Distributed Coordination Control
Kim, Byeong-Yeon; Oh, Kwang-Kyo; Ahn, Hyo-Sung
2014-01-01
This paper presents power coordination, power generation, and power flow control schemes for supply-demand balance in distributed grid networks. Consensus schemes using only local information are employed to generate power coordination, power generation and power flow control signals. For the supply-demand balance, it is required to determine the amount of power needed at each distributed power node. Also due to the different power generation capacities of each power node, coordination of pow...
Axial enrichment profile in advance nuclear energy power plant at supercritical-pressures
Energy Technology Data Exchange (ETDEWEB)
Tashakor, S. [Nuclear Science and Technology Research Institute (NSTRI), Tehran (Iran, Islamic Republic of). Reactor Research School; Islamic Azad Univ., Shiraz (Iran, Islamic Republic of). Dept. of Nuclear Engineering; Zarifi, E. [Nuclear Science and Technology Research Institute (NSTRI), Tehran (Iran, Islamic Republic of). Reactor Research School; Salehi, A.A. [Sharif University of Technology, Tehran (Iran, Islamic Republic of). Dept. of Nuclear Energy
2015-12-15
The High-Performance Light Water Reactor (HPLWR) is the European version of the advance nuclear energy power plant at Supercritical-pressure. A light water reactor at supercritical pressure, being currently under design, is the new generation of nuclear reactors. The aim of this study is to predict the HPLWR neutronic behavior of the axial enrichment profile with an average enrichment of 5 w/o U-235. Neutronic calculations are performed using WIMS and CITATION codes. Changes in neutronic parameter, such as Power Peaking Factor (PPF) are discussed in this paper.
Chong Chen; Xian Xu; Yuyu Miao; Gaoxin Zheng; Yong Sun; Xun Xu
2015-01-01
Purpose. This study aims to compare the accuracy of intraocular lens power calculation formulas in eyes with long axial lengths from Chinese patients subjected to cataract surgery. Methods. A total of 148 eyes with an axial length of >26 mm from 148 patients who underwent phacoemulsification with intraocular lens implantation were included. The Haigis, Hoffer Q, Holladay 1, and SRK/T formulas were used to calculate the refractive power of the intraocular lenses and the postoperative estimated...
Chen, Chong; Xu, Xian; Miao, Yuyu; Zheng, Gaoxin; Sun, Yong; Xu, Xun
2015-01-01
Purpose. This study aims to compare the accuracy of intraocular lens power calculation formulas in eyes with long axial lengths from Chinese patients subjected to cataract surgery. Methods. A total of 148 eyes with an axial length of >26 mm from 148 patients who underwent phacoemulsification with intraocular lens implantation were included. The Haigis, Hoffer Q, Holladay 1, and SRK/T formulas were used to calculate the refractive power of the intraocular lenses and the postoperative estimated power. Results. Overall, the Haigis formula achieved the lowest level of median absolute error 1.025 D (P 33 mm, and median absolute errors were significantly higher for those eyes than eyes with axial length = 26.01-30.00 mm. Absolute error was correlated with axial length for the SRK/T (r = 0.212, P = 0.010) and Hoffer Q (r = 0.223, P = 0.007) formulas. For axial lengths > 33 mm, eyes exhibited a postoperative hyperopic refractive error. Conclusions. The Haigis and SRK/T formulas may be more suitable for calculating intraocular lens power for eyes with axial lengths ranging from 26 to 33 mm. And for axial length over 33 mm, the Haigis formula could be more accurate. PMID:26793392
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
Microwave emission from an AXIAL-Virtual Cathode Oscillator driven by a compact pulsed power source
Shukla, R.; Sharma, S. K.; Banerjee, P.; Deb, P.; Prabaharan, T.; Das, R.; Kdas, B.; Adhikary, B.; Verma, R.; Shyam, A.
2012-11-01
For the generation of microwaves, Electron beam devices operating in vacuum are most widely used. For pulsed and high power microwave generation, Virtual cathode oscillators (VIRCATORs) are said to be simple in operation and construction. They are generally driven by a pulsed power source which gives high input powers to the Vircator connected as load. Vircator, depending upon its efficiency, converts the electrical input power to the microwave power. We are presenting the results of an axial Vircator operating in 2×10-4 mbar vacuum and is driven by a compact pulsed power source. The energy source and pulse compression is realized in very user friendly approach to run the system. The radiating system presently runs at relatively low powers but has the scope of reaching to high power by a logical improvement. A study of effect of collapsing diode impedance, of the vacuum field emission diode of the Vircator, on the microwave emission is presented in the paper. We are also presenting the microwave emission measurement conducted in the given system. Effect of vacuum is also studied to the extent of present experimental limits.
Microwave emission from an AXIAL-Virtual Cathode Oscillator driven by a compact pulsed power source
International Nuclear Information System (INIS)
For the generation of microwaves, Electron beam devices operating in vacuum are most widely used. For pulsed and high power microwave generation, Virtual cathode oscillators (VIRCATORs) are said to be simple in operation and construction. They are generally driven by a pulsed power source which gives high input powers to the Vircator connected as load. Vircator, depending upon its efficiency, converts the electrical input power to the microwave power. We are presenting the results of an axial Vircator operating in 2×10−4 mbar vacuum and is driven by a compact pulsed power source. The energy source and pulse compression is realized in very user friendly approach to run the system. The radiating system presently runs at relatively low powers but has the scope of reaching to high power by a logical improvement. A study of effect of collapsing diode impedance, of the vacuum field emission diode of the Vircator, on the microwave emission is presented in the paper. We are also presenting the microwave emission measurement conducted in the given system. Effect of vacuum is also studied to the extent of present experimental limits.
Contribution to the power distribution methodology uncertainties assessment
International Nuclear Information System (INIS)
The present methodology of safety margins in NPP Dukovany design power distribution calculations is based on the philosophy of engineering factors with errors defined on the bases of statistical approach of standard (95%) confidence intervals. On the level of FA power distribution the normality (normal density distribution) of this approach is tested and comparison with errors defined on the 95-percent probability at a 95-percent confidence level (shortly in statistics 95%/95%)) is provided. Practical applications are presented for several NPP Dukovany fuel cycles. The paper also deals briefly with difference between confidence interval and tolerance interval, with the problems of density distribution of mechanical engineering factor variables and solution of axial and radial error distribution like bivariate problem. (Author)
On one model of stellar clusters with axial symmetry and discrete mass distribution of stars
International Nuclear Information System (INIS)
A model of a stationary stellar cluster with axial symmetry and with stellar composition, homogeneous by mass is generalized for the case of a model with stellar composition discretely distributed by mass. From the solution obtained it follows that the summary mass density of stars D, statistic P and dynamic Q of pressure as well as mean circular velocity of stars Vo concide in the both models. However in the second model density distributions of a number of stars nsub(i) (i = 1,2..., k) are different for stellar groups various by mass and do not coincide with a summary density distribution of mass of a star. The latter result gives a possibility to explain a disk structure of SO-galaxies as a Unification of a great number of ring distributions of mean and light stars. Besides that this result allows to explain a bright ring structure, observed in some SO-galaxies, as a prevalence in a general disk structure of one numerous group of mean by mass stars with ring distribution. It is shown also that with some values of parameters a ring structure can form in bipolar clusters
Kr II and Xe II axial velocity distribution functions in a cross-field ion source
International Nuclear Information System (INIS)
Laser induced fluorescence measurements were carried out in a cross-field ion source to examine the behaviour of the axial ion velocity distribution functions (VDFs) in the expanding plasma. In the present paper, we focus on the axial VDFs of Kr II and Xe II ions. We examine the contourplots in a 1D-phase space (x,vx) representation in front of the exhaust channel and along the centerline of the ion source. The main ion beam, whose momentum corresponds to the ions that are accelerated through the whole potential drop, is observed. A secondary structure reveals the ions coming from the opposite side of the channel. We show that the formation of the neutralized ion flow is governed by the annular geometry. The assumption of a collisionless shock or a double layer due to supersonic beam interaction is not necessary. A non-negligible fraction of slow ions originates in local ionization or charge-exchange collision events between ions of the expanding plasma and atoms of the background residual gas. Slow ions that are produced near the centerline in the vicinity of the exit plane are accelerated toward the source body with a negative velocity leading to a high sputtering of front face. On the contrary, the ions that are produced in the vicinity of the channel exit plane are partially accelerated by the extended electric field.
Directory of Open Access Journals (Sweden)
Anita
2016-02-01
Full Text Available PURPOSE To compare the accuracy of Intraocular Lens (IOL power calculation formulae in high axial myopia. MATERIAL AND METHODS 27 eyes of 22 patients with axial length between 26mm to 30mm were studied. The eyes were divided in to two groups, Group 1 with AL 26-28mm consisting of 23 eyes and Group 2 with AL 28-30mm consisting of four eyes. The predictive accuracy of four formulae SRK-T, Hoffer Q, Haigis and Holladay 2 were evaluated and compared. The statistical analysis was carried out with SPSS Software 21.0 version with P value >0.05 considered significant. RESULTS The predictive capability within ±1 D of these formulae in Group 1 is 88% with SRK-T, 87% with Hoffer Q, 88% with Haigis and 91% with Holladay 2 and within ±0.5 D is 61%, 61%, 69% and 73% respectively. In Group 2 which consisted of 4 eyes with AL between 28-30mm the results were 83%, 83%, 84%, 90%, 59%, 61%, 70%, 71% respectively. CONCLUSION The performance of SRK-T, Hoffer Q and Haigis was comparable for target refraction of ±1.0 D, whereas Haigis and Holladay 2 gave relatively better results for target refraction of ±0.5 D for Group 1 and Haigis and Holladay 2 performed better for Group 2.
Strain distributions and electronic property modifications in Si/Ge axial nanowire heterostructures
Energy Technology Data Exchange (ETDEWEB)
Swadener, John Gregory [Los Alamos National Laboratory; Picraux, Samuel T [Los Alamos National Laboratory
2008-01-01
Molecular dynamics simulations were carried out for Si/Ge axial nanowire heterostructures using modified effective atom method (MEAM) potentials. A Si-Ge MEAM interatomic cross potential was developed based on available experimental data and used for these studies. The atomic distortions and strain distributions near the Si/Ge interfaces are predicted for nanowires with their axes oriented along the [111] direction. The cases of 10 and 25 nm diameter SilGe biwires and of 25 nm diameter Si/Ge/Si axial heterostructures with the Ge disc 1 nm thick were studied. Substantial distortions in the height of the atoms adjacent to the interface were found for the biwires, but not for the Ge discs. Strains as high as 3.5% were found for the Ge disc and values of 2 to 2.5% were found at the Si and Ge interfacial layers in the biwires. Deformation potential theory was used to estimate the influence of the strains on the band gap, and reductions in band gap to as small as 40% of bulk values are predicted for the Ge discs. Localized regions of increased strain and resulting energy minima were also found within the Si/Ge biwire interfaces with the larger effects on the Ge side of the interface. The regions of strain maxima near and within the interfaces are anticipated to be useful for tailoring band gaps and producing quantum confinement of carriers. These results suggest nanowire heterostructures provide greater design flexibility in band structure modification than is possible with planar layer growth.
Radulović, Vladimir; Štancar, Žiga; Snoj, Luka; Trkov, Andrej
2014-02-01
The calculation of axial neutron flux distributions with the MCNP code at the JSI TRIGA Mark II reactor has been validated with experimental measurements of the (197)Au(n,γ)(198)Au reaction rate. The calculated absolute reaction rate values, scaled according to the reactor power and corrected for the flux redistribution effect, are in good agreement with the experimental results. The effect of different cross-section libraries on the calculations has been investigated and shown to be minor. PMID:24316530
Power Quality in DC Power Distribution Systems and Microgrids
Stephen Whaite; Brandon Grainger; Alexis Kwasinski
2015-01-01
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 qu...
Energy loss distributions of relativistic protons axially channeled in a bent silicon crystal
Energy Technology Data Exchange (ETDEWEB)
Stojanov, Nace, E-mail: nacestoj@pmf.ukim.mk [Institute of Physics, Faculty of Natural Sciences and Mathematics, Sts. Cyril and Methodius University, P.O. Box 162, 1000 Skopje (Macedonia, The Former Yugoslav Republic of); Petrović, Srdjan; Nešković, Nebojša [Laboratory of Physics (010), Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia)
2013-05-01
A detailed study of the energy loss distributions of the relativistic protons axially channeled in the bent < 100 > Si crystals is presented in this work. The bending angle was varied from 0 to 20 μrad, while the crystal thickness was equal to 1 mm. The proton energy was chosen to be 7 TeV in accordance with the Large Hadron Collider (LHC) project, at the European Organization for Nuclear Research (CERN), in Geneva, Switzerland. The energy loss distributions of the channeled protons were generated using the numerical solution of the proton equations of motion in the transverse plane and the computer simulation method. An accurate energy loss model was used, which takes into account the trajectory dependence of the energy loss of protons during their motion through the crystal channels. Further, the dispersion of the proton’s scattering angle caused by its collisions with the electrons of the crystal and the divergence of the proton beam were taken into account. The calculated dependence of the number of dechanneled protons on the bending angle was excellently fitted by the Gompertz type dechanneling function.
Development of an Axial Flux MEMS BLDC Micromotor with Increased Efficiency and Power Density
Directory of Open Access Journals (Sweden)
Xiaofeng Ding
2015-06-01
Full Text Available This paper presents a rigorous design and optimization of an axial flux microelectromechanical systems (MEMS brushless dc (BLDC micromotor with dual rotor improving both efficiency and power density with an external diameter of only around 10 mm. The stator is made of two layers of windings by MEMS technology. The rotor is developed by film permanent magnets assembled over the rotor yoke. The characteristics of the MEMS micromotor are analyzed and modeled through a 3-D magnetic equivalent circuit (MEC taking the leakage flux and fringing effect into account. Such a model yields a relatively accurate prediction of the flux in the air gap, back electromotive force (EMF and electromagnetic torque, whilst being computationally efficient. Based on 3-D MEC model the multi-objective firefly algorithm (MOFA is developed for the optimal design of this special machine. Both 3-D finite element (FE simulation and experiments are employed to validate the MEC model and MOFA optimization design.
Particle capture in axial magnetic filters with power law flow model
Abbasov, T; Koksal, M
1999-01-01
A theory of capture of magnetic particle carried by laminar flow of viscous non-Newtonian (power law) fluid in axially ordered filters is presented. The velocity profile of the fluid flow is determined by the Kuwabara-Happel cell model. For the trajectory of the particle, the capture area and the filter performance simple analytical expressions are obtained. These expressions are valid for particle capture processes from both Newtonian and non-Newtonian fluids. For this reason the obtained theoretical results make it possible to widen the application of high-gradient magnetic filtration (HGMF) to other industrial areas. For Newtonian fluids the theoretical results are shown to be in good agreement with the experimental ones reported in the literature. (author)
Simultaneous distribution of AC and DC power
Polese, Luigi Gentile
2015-09-15
A system and method for the transport and distribution of both AC (alternating current) power and DC (direct current) power over wiring infrastructure normally used for distributing AC power only, for example, residential and/or commercial buildings' electrical wires is disclosed and taught. The system and method permits the combining of AC and DC power sources and the simultaneous distribution of the resulting power over the same wiring. At the utilization site a complementary device permits the separation of the DC power from the AC power and their reconstruction, for use in conventional AC-only and DC-only devices.
Diffusion air effects on the soot axial distribution concentration in a premixed acetylene/air flame
Energy Technology Data Exchange (ETDEWEB)
Fassani, Fabio Luis; Santos, Alex Alisson Bandeira; Goldstein Junior, Leonardo [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Engenharia Termica e de Fluidos]. E-mails: fassani@fem.unicamp.br; absantos@fem.unicamp.br; leonardo@fem.unicamp.br; Ferrari, Carlos Alberto [Universidade Estadual de Campinas, SP (Brazil). Inst. de Fisica. Dept. de Eletronica Quantica]. E-mail: ferrari@ifi.unicamp.br
2000-07-01
Soot particles are produced during the high temperature pyrolysis or combustion of hydrocarbons. The emission of soot from a combustor, or from a flame, is determined by the competition between soot formation and its oxidation. Several factors affect these processes, including the type of fuel, the air-to-fuel ratio, flame temperature, pressure, and flow pattern. In this paper, the influence of the induced air diffusion on the soot axial distribution concentration in a premixed acetylene/air flame was studied. The flame was generated in a vertical axis burner in which the fuel - oxidant mixture flow was surrounded by a nitrogen discharge coming from the annular region between the burner tube and an external concentric tube. The nitrogen flow provided a shield that protected the flame from the diffusion of external air, enabling its control. The burner was mounted on a step-motor driven, vertical translation table. The use of several air-to-fuel ratios made possible to establish the sooting characteristics of this flame, by measuring soot concentration along the flame height with a non-intrusive laser light absorption technique. (author)
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...... 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 and...
Power distribution changes caused by subcooled nucleate boiling at Callaway Nuclear Power Plant
International Nuclear Information System (INIS)
This paper reports the results of an evaluation undertaken by Union Electric (UE) and Westinghouse to explain anomalous behavior of the core axial power distribution at the Callaway Nuclear Power Plant. The behavior was characterized by a gradual unexpected power shift toward the bottom of the core and was first detected during cycle 4 at a core average burnup of approximately 7,000 MWD/MTU. Once started, the power shift continued until burnup effects became dominant and caused power to shift back to the top of the core at the end of the cycle. In addition to the anomalous power distribution, UE observed that estimated critical control rod position (ECP) deviations increased to over 500 pcm (0.5%Δk/k) during Cycles 4 and 5. ECPs for plant restarts that occurred early in each cycle agreed well with measured critical conditions. However, this agreement disappeared for restarts that occurred later in core life. After analyzing relevant data, performing scoping calculations and reviewing industry experience, the authors concluded that the power distribution anomaly was most likely caused by subcooled nucleate boiling. Crud deposition on the fuel was believed to enhance the subcooled boiling. The ECP deviations were a secondary effect of the power shift, since void fraction, axial burnup and xenon distributions departed design predictions during a substantial portion of the fuel cycles. Significant evidence supporting these conclusions include incore detector indications of flux depressions between intermediate flow mixing (IFM) and structural grids. In addition, visual exam results show the presence of crud deposits on fuel pins
Directory of Open Access Journals (Sweden)
Siatiri H
2000-08-01
Full Text Available This study was conducted to define the prevalence and types of corneal astigmatism in relation with corneal optical power, axial length, sex and patient age. 641 cataract patients were included in a descriptive study. Complete eye examinations were included in a descriptive study. Complete eye examinations were performed. The data were analysed by standard procedures including analysis of variance, chi square test and multiple linear regression models. With the rule, astigmatism was 55.6% in younger cases and against the rule astigmatism was 55.6% in younger cases and against the rule astigmatism was 43.7% in older cases (P<0.0001. Against the rule astigmatism was 55.8% in older males and 34.6% in older females (P<0.0001.There was 0.023d decrease in kpol for each year increase in age 1 (P<0.0001. Axial length in males was 23.35±1.79 mm (P<0.05 for second degree model to show relationship between astigmatism and axial length R2 was 0.019 and 0.03 by increasing axial length up to 26 mm corneal power decreased, but further increase in axial length led to corneal power increase. For each diopter increase in corneal power there was 0.1 diopetr increase in net astigmatism (P<0.0001. In corneal powers less than 45.5 diopter there was no difference between direction of astigmatism, but in corneal powers more than 45.5 diopter with the rule astigmatism was dominated (P=0.01. younger cases had more with the rule astigmatism andolder cases had more against the rule astigmatism. Against the rule astigmatism was more common in older males than in older females. With the rule astigmatism ratio shifted to ATR astigmastism ratio with age but there was no change in against the rule astigmatism ratio with age. Males had 0.22 mm axial length more than females. There was significant relationship between axial length and net astigmatism. Abnormal size eyes had more astigmatism.Emmetropization mechanism of cornea did not work for eyes longer than 26 mm. Myopia was
Distributed Generation and Resilience in Power Grids
Scala, Antonio; Chessa, Alessandro; Caldarelli, Guido; Damiano, Alfonso
2012-01-01
We study the effects of the allocation of distributed generation on the resilience of power grids. We find that an unconstrained allocation and growth of the distributed generation can drive a power grid beyond its design parameters. In order to overcome such a problem, we propose a topological algorithm derived from the field of Complex Networks to allocate distributed generation sources in an existing power grid.
Directory of Open Access Journals (Sweden)
Ryo Obata
Full Text Available PURPOSE: It has not been clarified whether early age-related macular degeneration (AMD is associated with cone photoreceptor distribution. We used adaptive optics fundus camera to examine cone photoreceptors in the macular area of aged patients and quantitatively analyzed its relationship between the presence of early AMD and cone distribution. METHODS: Sixty cases aged 50 or older were studied. The eyes were examined with funduscopy and spectral-domain optical coherence tomography to exclude the eyes with any abnormalities at two sites of measurement, 2° superior and 5° temporal to the fovea. High-resolution retinal images with cone photoreceptor mosaic were obtained with adaptive optics fundus camera (rtx1, Imagine Eyes, France. After adjusting for axial length, cone packing density was calculated and the relationship with age, axial length, or severity of early AMD based on the age-related eye disease study (AREDS classification was analyzed. RESULTS: Patient's age ranged from 50 to 77, and axial length from 21.7 to 27.5 mm. Mean density in metric units and that in angular units were 24,900 cells/mm2, 2,170 cells/deg2 at 2° superior, and 18,500 cells/mm2, 1,570 cels/deg2 at 5° temporal, respectively. Axial length was significantly correlated with the density calculated in metric units, but not with that in angular units. Age was significantly correlated with the density both in metric and angular units at 2° superior. There was no significant difference in the density in metric and angular units between the eyes with AREDS category one and those with categories two or three. CONCLUSION: Axial length and age were significantly correlated with parafoveal cone photoreceptor distribution. The results do not support that early AMD might influence cone photoreceptor density in the area without drusen or pigment abnormalities.
W. F. Harris
2009-01-01
If an intraocular lens is displaced or if its power is changed what are the consequences for the refractive compensation of the eye? Gaussian optics is used to obtain explicit formulae for the sensitivityof the corneal-plane refractive compensation (also called the refraction, refractive state, etc) to change in power and axial displacement of a thin intraocular lens implanted in a simple eye. In particular, for a pseudophakic Gullstrand simplified eye with intraocular lens placed 5 mm behi...
W. F. Gool; R.D. van Gool
2009-01-01
If an intraocular lens is displaced or if its power is changed what are the consequences for the refractive compensation of the eye? Gaussian optics is used to obtain explicit formulae for the sensitivityof the corneal-plane refractive compensation (also called the refraction, refractive state, etc) to change in power and axial displacement of a thin intraocular lens implanted in a simple eye. In particular, for a pseudophakic Gullstrand simplified eye withintraocular lens placed 5 mm behin...
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...... 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...
Distributed systems for protecting nuclear power stations
International Nuclear Information System (INIS)
The advantages of distributed control systems for the control of nuclear power stations are obviously of great interest. Some years ago, EPRI, (Electric Power Research Institute) showed that multiplexing the signals is technically feasible, that it enables the availability specifications to be met and costs to be reduced. Since then, many distributed control systems have been proposed by the manufacturers. This note offers some comments on the application of the distribution concept to protection systems -what should be distributed- and ends with a brief description of a protection system based on microprocessors for the pressurized power stations now being built in France
Control of renewable distributed power plants
Bullich Massagué, Eduard
2015-01-01
The main objective of this master thesis is to design a power plant controller for a photo- voltaic (PV) power plant. In a first stage, the current situation of the status of the electrical grid is analysed. The electrical network structure is moving from a conventional system (with centralized power generation, unidirectional power ows, easy control) to a smart grid system consisting on distributed generation, renewable energies, smart and complex control architecture and ...
Directory of Open Access Journals (Sweden)
W. F. Harris
2009-12-01
Full Text Available If an intraocular lens is displaced or if its power is changed what are the consequences for the refractive compensation of the eye? Gaussian optics is used to obtain explicit formulae for the sensitivityof the corneal-plane refractive compensation (also called the refraction, refractive state, etc to change in power and axial displacement of a thin intraocular lens implanted in a simple eye. In particular, for a pseudophakic Gullstrand simplified eye with intraocular lens placed 5 mm behind the cornea the sensitivity to errors in the power of the intraocular lens is about 71 . 0 − 71 for an intraocular lens of power for an intraocular lens of power 20 D, that is, the refractive compensation decreases by about 0.71 dioptres per dioptre increase in the power of the intraocular lens. More generally the sensitivity is approximately ( m 0037 . 0 63 . 0 F − − 0.63 ( 003 . 0 63 . 0 − − (0.0037mF where FI is the power of the intraocular lens. Also for Gullstrand’s simplified eye the sensitivity of refractive compensation to axial displacement of the intraocular lens is approximately linear in FI about (64D FI, in fact. That is, for each dioptre of the power of the intraocular lens the refractive compensation increases by about 0.064 dioptres per millimetre of axial displacement towards the retina.
Siatiri H
2000-01-01
This study was conducted to define the prevalence and types of corneal astigmatism in relation with corneal optical power, axial length, sex and patient age. 641 cataract patients were included in a descriptive study. Complete eye examinations were included in a descriptive study. Complete eye examinations were performed. The data were analysed by standard procedures including analysis of variance, chi square test and multiple linear regression models. With the rule, astigmatism was 55.6% in ...
The future of distributed power in Alberta
International Nuclear Information System (INIS)
Maxim Power Corporation is a provider of distributed energy and environmental solutions with a total of 55 MW of installed generating capacity in Canada, Europe and Asia, with 35 MW in Alberta. The 8 MW Taber facility in southern Alberta was described. Maxim operates 25 other small scale power generation stations (1 MW units) across 4 sites in southern Alberta. All the sites are interconnected at 25 kV and are eligible for distribution credits. The 3 MW EVI facility which utilizes solution gas was also described in the PowerPoint presentation. Maxim operates an additional 3 projects totaling 10 MW. The paper made reference to issues regarding market attributes for distributed power, policy framework and the transition to a competitive power market in Alberta. The chronology of events in Alberta's power market from August 2000 to June 2001 was outlined. The impacts of deregulation on distributed power include: (1) artificially low price environment from market intervention, (2) high efficiency cogeneration opportunities have been eliminated, (3) business failures and reduced investment, and (4) private investment not afforded the same alternative cost recovery mechanisms as the Alberta balancing pool. The presentation concluded with a report card for Alberta's deregulation, giving a grade F for both present and future opportunities for distributed power in Alberta. 2 figs
Power Electronics Control of Wind Energy in Distributed Power System
DEFF Research Database (Denmark)
Iov, Florin; Ciobotaru, Mihai; Blaabjerg, Frede
2008-01-01
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...... energy at the end-user should also be set up. Deregulation of energy has in the past lowered the investment in larger power plants, which means the need for new electrical power sources will be high in the near future. Two major technologies will play important roles to solve the future problems. One...... 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...
Custom power - the utility solution to distribution power quality
Energy Technology Data Exchange (ETDEWEB)
Woodley, N.H. [Westinghouse Electric Corp., Pittsburgh, PA (United States)
1997-04-01
The design of custom power products for electric power distribution system was discussed. Problems with power quality that result in loss of production to critical processes are costly and create a problem for the customer as well as the electric utility. Westinghouse has developed power quality improvement equipment for customers and utilities, using new technologies based on power electronics concepts. The Distribution Static Compensator (DSTATCOM) is a fast response, solid-state power controller that provides flexible voltage control for improving power quality at the point of connection to the utility`s 4.16 to 69 kV distribution feeder. STATCOM is a larger version of the DSTATCOM that can be used to solve voltage flicker problems caused by electric arc furnaces. Westinghouse has also developed a Dynamic Voltage Restorer (DVR) which protects a critical customer plant load from power system voltage disturbances. Solid-State Breakers (SSB) have also been developed which offer a solution to many of the distribution system problems that result in voltage sags, swells, and power outages. 6 refs., 8 figs.
Energy Technology Data Exchange (ETDEWEB)
Mayhall, D J; Stein, W; Gronberg, J B
2006-05-15
We have performed preliminary computer-based, transient, magnetostatic calculations of the eddy-current power loss in rotating titanium-alloy and aluminum wheels and wheel rims in the predominantly axially-directed, steady magnetic fields of two small, solenoidal coils. These calculations have been undertaken to assess the eddy-current power loss in various possible International Linear Collider (ILC) positron target wheels. They have also been done to validate the simulation code module against known results published in the literature. The commercially available software package used in these calculations is the Maxwell 3D, Version 10, Transient Module from the Ansoft Corporation.
Space Solar Power Management and Distribution (PMAD)
Lynch, Thomas H.
2000-01-01
This paper presents, in viewgraph form, SSP PMAD (Space Solar Power Management and Distribution). The topics include: 1) Architecture; 2) Backside Thermal View; 3) Solar Array Interface; 4) Transformer design and risks; 5) Twelve phase rectifier; 6) Antenna (80V) Converters; 7) Distribution Cables; 8) Weight Analysis; and 9) PMAD Summary.
Cathode power distribution system and method of using the same for power distribution
Energy Technology Data Exchange (ETDEWEB)
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.
Interpretable Distribution Features with Maximum Testing Power
Jitkrittum, Wittawat; Szabo, Zoltan; Chwialkowski, Kacper; Gretton, Arthur
2016-01-01
Two semimetrics on probability distributions are proposed, given as the sum of differences of expectations of analytic functions evaluated at spatial or frequency locations (i.e, features). The features are chosen so as to maximize the distinguishability of the distributions, by optimizing a lower bound on test power for a statistical test using these features. The result is a parsimonious and interpretable indication of how and where two distributions differ locally. An empirical estimate of...
Intelligent Systems for Power Management and Distribution
Button, Robert M.
2002-01-01
The motivation behind an advanced technology program to develop intelligent power management and distribution (PMAD) systems is described. The program concentrates on developing digital control and distributed processing algorithms for PMAD components and systems to improve their size, weight, efficiency, and reliability. Specific areas of research in developing intelligent DC-DC converters and distributed switchgear are described. Results from recent development efforts are presented along with expected future benefits to the overall PMAD system performance.
International Nuclear Information System (INIS)
Taking as an example South-Ukrainian WWER-1000 type NPP the problems related to the possibility of obtaining integral characteristics of power distribution by readings of out of-pile ionization chambers (IC) are considered. The regression dependence of IC readings on axial offset (AO)-characteristic of peak- power distribution along the core length is investigated. This dependence proved to be linear. For power evaluation linear combination of IC readings is used. Simultaneously by the readings of two IC located at different core length the evaluation of AO values can be performed
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.
Optimal power flow for distribution networks with distributed generation
Radosavljević Jordan; Jevtić Miroljub; Klimenta Dardan; Arsić Nebojša
2015-01-01
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....
Custom power: The utility solution to distribution power quality
Energy Technology Data Exchange (ETDEWEB)
Clouston, J.; Sundaram, A.; Woodley, N. H.
1997-06-01
The prevention of power quality problems that result in production losses on the customer`s side of the meter, and system solutions and/or power quality improvement equipment for both sides (the utility and the customer) were discussed. Solutions to this problem may lie in new technology based on power electronics-based concepts, developed as part of EPRI`s Custom Power Program. Several recent custom power products were reviewed such as a distribution static compensator (DSTATCOM), a dynamic voltage restorer (DVR), and solid state breakers (SSB)/transfer switch (SSTS). Details of their respective purpose and specific function were provided. A formula for economic justification for Custom Power solutions was also suggested. Although equipment costs were said to vary widely depending on application, an analysis of annual disturbance events indicates that it is possible to achieve a simple two-year payback, which is used by many industries as a `go-no-go` project decision criteria. 7 figs.
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
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....
Reliability assessment of distribution power systems including distributed generations
International Nuclear Information System (INIS)
Nowadays, power systems have reached a good level of reliability. Nevertheless, considering the modifications induced by the connections of small independent producers to distribution networks, there's a need to assess the reliability of these new systems. Distribution networks present several functional characteristics, highlighted by the qualitative study of the failures, as dispersed loads at several places, variable topology and some electrotechnical phenomena which must be taken into account to model the events that can occur. The adopted reliability calculations method is Monte Carlo simulations, the probabilistic method most powerful and most flexible to model complex operating of the distribution system. We devoted a first part on the case of a 20 kV feeder to which a cogeneration unit is connected. The method was applied to a software of stochastic Petri nets simulations. Then a second part related to the study of a low voltage power system supplied by dispersed generations. Here, the complexity of the events required to code the method in an environment of programming allowing the use of power system calculations (load flow, short-circuit, load shedding, management of units powers) in order to analyse the system state for each new event. (author)
Power distribution studies for CMS forward tracker
International Nuclear Information System (INIS)
The Electronic Systems Engineering Department of the Computing Division at the Fermi National Accelerator Laboratory is carrying out R and D investigations for the upgrade of the power distribution system of the Compact Muon Solenoid (CMS) Pixel Tracker at the Large Hadron Collider (LHC). Among the goals of this effort is that of analyzing the feasibility of alternative powering schemes for the forward tracker, including DC to DC voltage conversion techniques using commercially available and custom switching regulator circuits. Tests of these approaches are performed using the PSI46 pixel readout chip currently in use at the CMS Tracker. Performance measures of the detector electronics will include pixel noise and threshold dispersion results. Issues related to susceptibility to switching noise will be studied and presented. In this paper, we describe the current power distribution network of the CMS Tracker, study the implications of the proposed upgrade with DC-DC converters powering scheme and perform noise susceptibility analysis.
Lisnyak, M.; Pipa, A. V.; Gorchakov, S.; Iseni, S.; Franke, St.; Khapour, A.; Methling, R.; Weltmann, K.-D.
2015-09-01
Spectroscopic investigations of free-burning vacuum arcs in diffuse mode with CuCr electrodes are presented. The experimental conditions of the investigated arc correspond to the typical system for vacuum circuit breakers. Spectra of six species Cu I, Cu II, Cu III, Cr I, Cr II, and Cr III have been analyzed in the wavelength range 350-810 nm. The axial intensity distributions were found to be strongly dependent on the ionization stage of radiating species. Emission distributions of Cr II and Cu II can be distinguished as well as the distributions of Cr III and Cu III. Information on the axial distribution was used to identify the spectra and for identification of overlapping spectral lines. The overview spectra and some spectral windows recorded with high resolution are presented. Analysis of axial distributions of emitted light, which originates from different ionization states, is presented and discussed.
Reactor power distribution pattern judging device
International Nuclear Information System (INIS)
The judging device of the present invention comprises a power distribution readout system for intaking a power value from a fuel segment, a neural network having an experience learning function for receiving a power distribution value as an input variant, mapping it into a desirable property and self-organizing the map, and a learning date base storing a plurality of learnt samples. The read power distribution is classified depending on the similarity thereof with any one of representative learnt power distribution, and the corresponding state of the reactor core is outputted as a result of the judgement. When an error is found in the classified judging operation, erroneous cases are additionally learnt by using the experience and learning function, thereby improving the accuracy of the reactor core characteristic estimation operation. Since the device is mainly based on the neural network having a self-learning function and a pattern classification and judging function, a judging device having a human's intuitive pattern recognition performance and a pattern experience and learning performance is obtainable, thereby enabling to judge the state of the reactor core accurately. (N.H.)
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.
Power quality in electric distribution systems
International Nuclear Information System (INIS)
the power quality of the electric system is defined by the constant values of the voltage and frequency, the good value of the power factor close to unity, and balanced three phase voltages and currents. capacitors are widely installed in distribution systems for reactive power compensation to achieve power and energy loss reduction, voltage regulation and system capacity release. the extent of these benefits depends greatly on low the capacitors are placed on the system . the problem of how to place capacitors on the system such that these benefits are achieved and / or maximized against the cost associated with the capacitor placement is termed the general capacitor placement problem.the presented mathematical model has been developed to determine the size, number, and location of fixed capacitor banks that will maximize the saving derived from reduction in peak power and energy loss, and that will minimize the capital and installation costs of capacitors
Intelligent distributed control for nuclear power plants
International Nuclear Information System (INIS)
In September of 1989 work began on the DOE University Program grant DE-FG07-89ER12889. The grant provides support for a three year project to develop and demonstrate Intelligent Distributed Control (IDC) for Nuclear Power Plants. The body of this First Annual Technical Progress report summarizes the first year tasks while the appendices provide detailed information presented at conference meetings. One major addendum report, authored by M.A. Schultz, describes the ultimate goals and projected structure of an automatic distributed control system for EBR-2. The remaining tasks of the project develop specific implementations of various components required to demonstrate the intelligent distributed control concept
Power distribution control in BN-600 reactor by method of gamma-scanning of fuel assemblies
International Nuclear Information System (INIS)
Acceptability, convenience and reliability of γ-scanning of fuels assembles at fast reactor NPP have been analyzed and demonstrated. Error of the procedure is amount 3-6% for different fuel assemblies. The procedure is recommended as optimum one for the constructed BN-800 and perspective fast reactors. Findings allow conclusion on the accordance of BN-600 fuel assemblies powers with design parameters and insignificant (in the limits of observation accuracy) changing power distribution in new BN-600 01M2 reactor core. Experimental procedure is modernized and optimized, three cycles of measurement are realized, new experimental data on the character of radial and axial distributions of neutron field are received
Population distribution around Bushehr nuclear power plant
International Nuclear Information System (INIS)
Population distribution around the nuclear power plant is one of the most important factors to be considered. For the Bushehr nuclear power plant, information on current population distribution in the external zone up to a 80 kilometer radius in the vicinity of the site is collected. Also a projection of population for the plant lifetime has been made. Finally, the collected data was classified according to the age and sex. For this purpose, the area around the power plant was divided into concentric rings, and the rings were divided into 16 sectors. The population from 366 villages and 5 towns are about 328,000 inhabitants. In this survey, the population for 1985 was prepared on the basis of the 1977 census, and the results are indicated on the figures and tables. The above information will be used in evaluation of the potential radiological impact of normal and accidental releases, planning of emergency measures, and calculation of individual and collective doses
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)
A Study for Improvement of Power Distribution Component (PDC)
Energy Technology Data Exchange (ETDEWEB)
Kim, Young-Choon; Lee, Sang-Yong; Sohn, Chang-Ho; Kim, Jung-Seon [Samchang Enterprise Co. LTD., Ulsan (Korea, Republic of)
2007-07-01
The process control cabinet consists of several subracks. Each sub-rack power delivered by backplane through power distribution component located in each sub-rack from main power. This power distribution component dissipates power like resistor between main power supply and cards. So some voltage drops are occurred. This paper studies power distribution component improvement to reduce damage by over voltage, over current, voltage drop and to keep reverse polarity protection, power switching.
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
Power Management and Distribution System Developed for Thermionic Power Converters
Baez, Anastacio N.
1998-01-01
A spacecraft solar, bimodal system combines propulsion and power generation into a single integrated system. An Integrated Solar Upper Stage (ISUS) provides orbital transfer capabilities, power generation for payloads, and onboard propulsion to the spacecraft. A key benefit of a bimodal system is a greater payload-to-spacecraft mass ratio resulting in lower launch vehicle requirements. Scaling down to smaller launch vehicles increases space access by reducing overall mission cost. NASA has joined efforts with the Air Force Phillips Laboratory to develop enabling technologies for such a system. The NASA/Air Force bimodal concept uses solar concentrators to focus energy into an integrated power plant. This power plant consists of a graphite core that stores thermal energy within a cavity. An array of thermionic converters encircles the graphite cavity and provides electrical energy conversion functions. During the power generation phase of the bimodal system, the thermionic converters are exposed to the heated cavity and convert the thermal energy to electricity. Near-term efforts of the ISUS bimodal program are focused on a ground demonstration of key technologies in order to proceed to a full space flight test. Thermionic power generation is one key technology of the bimodal concept. Thermionic power converters impose unique operating requirements upon a power management and distribution (PMAD) system design. Single thermionic converters supply large currents at very low voltages. Operating voltages can vary over a range of up to 3 to 1 as a function of operating temperature. Most spacecraft loads require regulated 28-volts direct-current (Vdc) power. A combination of series-connected converters and powerprocessing boosters is required to deliver power to the spacecraft's payloads at this level.
Intelligent distributed control for nuclear power plants
Energy Technology Data Exchange (ETDEWEB)
Klevans, E.H.; Edwards, R.M.; Ray, A.; Lee, K.Y.; Garcia, H.E.: Chavez, C.M.; Turso, J.A.; BenAbdennour, A.
1991-01-01
In September of 1989 work began on the DOE University Program grant DE-FG07-89ER12889. The grant provides support for a three year project to develop and demonstrate Intelligent Distributed Control (IDC) for Nuclear Power Plants. The body of this Second Annual Technical Progress report covers the period from September 1990 to September 1991. It summarizes the second year accomplishments while the appendices provide detailed information presented at conference meetings. These are two primary goals of this research. The first is to combine diagnostics and control to achieve a highly automated power plant as described by M.A. Schultz, a project consultant during the first year of the project. This philosophy, as presented in the first annual technical progress report, is to improve public perception of the safety of nuclear power plants by incorporating a high degree automation where greatly simplified operator control console minimizes the possibility of human error in power plant operations. A hierarchically distributed control system with automated responses to plant upset conditions is the focus of our research to achieve this goal. The second goal is to apply this research to develop a prototype demonstration on an actual power plant system, the EBR-II steam plant.
Intelligent distributed control for nuclear power plants
International Nuclear Information System (INIS)
In September of 1989 work began on the DOE University Program grant DE-FG07-89ER12889. The grant provides support for a three year project to develop and demonstrate Intelligent Distributed Control (IDC) for Nuclear Power Plants. The body of this Second Annual Technical Progress report covers the period from September 1990 to September 1991. It summarizes the second year accomplishments while the appendices provide detailed information presented at conference meetings. These are two primary goals of this research. The first is to combine diagnostics and control to achieve a highly automated power plant as described by M.A. Schultz, a project consultant during the first year of the project. This philosophy, as presented in the first annual technical progress report, is to improve public perception of the safety of nuclear power plants by incorporating a high degree automation where greatly simplified operator control console minimizes the possibility of human error in power plant operations. A hierarchically distributed control system with automated responses to plant upset conditions is the focus of our research to achieve this goal. The second goal is to apply this research to develop a prototype demonstration on an actual power plant system, the EBR-II steam plant
Intelligent distributed control for nuclear power plants
International Nuclear Information System (INIS)
This project was initiated in September 1989 as a three year project to develop and demonstrate Intelligent Distributed Control (IDC) for Nuclear Power Plants. The body of this Third Annual Technical Progress report summarizes the period from September 1991 to October 1992. There were two primary goals of this research project. The first goal was to combine diagnostics and control to achieve a highly automated power plant as described by M.A. Schultz. His philosophy, is to improve public perception of the safety of nuclear power plants by incorporating a high degree of automation where a greatly simplified operator control console minimizes the possibility of human error in power plant operations. To achieve this goal, a hierarchically distributed control system with automated responses to plant upset conditions was pursued in this research. The second goal was to apply this research to develop a prototype demonstration on an actual power plant system, the EBR-2 stem plant. Emphasized in this Third Annual Technical Progress Report is the continuing development of the in-plant intelligent control demonstration for the final project milestone and includes: simulation validation and the initial approach to experiment formulation
Uncertainty evaluation in BEACON power distribution monitoring
International Nuclear Information System (INIS)
BEACON is an advanced operational core support package that has a three-dimensional nodal code as its cornerstone. The three-dimensional calculation includes all necessary pressurized water reactor feedback effects. The generation of the measured power distribution from the core instrumentation is one of the primary functions of the core-monitoring software. The purpose of this paper is to discuss evaluation of the uncertainty in the measured assembly power from the BEACON system. The study covers not only the normal operating conditions, but off-normal situations to demonstrate BEACON's applicability for that condition
Decentralised electrical distribution network in power plants
International Nuclear Information System (INIS)
A centralised network is a dominating network solution in today's power plants. In this study a centralised and a decentralised network were designed in order to compare them economically and technically. The emphasis of this study was on economical aspects, but also the most important technical aspects were included. The decentralised network requires less space and less cabling since there is no switchgear building and distribution transformers are placed close to the consumption in the field of a power plant. MV-motors and distribution transformers build up a ring. Less cabling and an absent switchgear building cause considerable savings. Component costs of both of the networks were estimated by using data from fulfilled power plant projects and turned out to be smaller for the decentralised network. Simulations for the decentralised network were done in order to find a way to carry out earth fault protection and location. It was found out that in high resistance earthed system the fault distance can be estimated by a relatively simple method. The decentralised network uses a field bus, which offers many new features to the automation system of a power plant. Diversified information can be collected from the protection devices in order to schedule only the needed maintenance duties at the right time. Through the field bus it is also possible to control remotely a power plant. The decentralised network is built up from ready-to-install modules. These modules are tested by the module manufacturer decreasing the need for field testing dramatically. The work contribution needed in the electrification and the management of a power plant project reduces also due the modules. During the lifetime of a power plant, maintenance is easier and more economical. (orig.)
Adaptive intelligent power systems: Active distribution networks
International Nuclear Information System (INIS)
Electricity networks are extensive and well established. They form a key part of the infrastructure that supports industrialised society. These networks are moving from a period of stability to a time of potentially major transition, driven by a need for old equipment to be replaced, by government policy commitments to cleaner and renewable sources of electricity generation, and by change in the power industry. This paper looks at moves towards active distribution networks. The novel transmission and distribution systems of the future will challenge today's system designs. They will cope with variable voltages and frequencies, and will offer more flexible, sustainable options. Intelligent power networks will need innovation in several key areas of information technology. Active control of flexible, large-scale electrical power systems is required. Protection and control systems will have to react to faults and unusual transient behaviour and ensure recovery after such events. Real-time network simulation and performance analysis will be needed to provide decision support for system operators, and the inputs to energy and distribution management systems. Advanced sensors and measurement will be used to achieve higher degrees of network automation and better system control, while pervasive communications will allow networks to be reconfigured by intelligent systems
Complexity of Resilient Power Distribution Networks
International Nuclear Information System (INIS)
Power Systems in general and specifically the problems of communication, control, and coordination in human supervisory control of electric power transmission and distribution networks constitute a good case study for resilience engineering. Because of the high cost and high impact on society of transmission disturbances and blackouts and the vulnerability of power networks to terrorist attacks, Transmission Systems Operators (TSOs) are already focusing on organizational structures, procedures, and technical innovations that could improve the flexibility and robustness of power Systems and achieve the overall goal of providing secure power supply. For a number of reasons however the complexity of power Systems is increasing and new problems arise for human supervisory control and the ability of these Systems to implement fast recovery from disturbances. Around the world power Systems are currently being restructured to adapt to regional electricity markets and secure the availability, resilience and sustainability of electric power generation, transmission and distribution. This demands a reconsideration of the available decision support, the activity of human supervisory control of the highly automated processes involved and the procedures regulating it, as well as the role of the TSOs and the regional, national and international organizations set up to manage their activity. Unfortunately we can expect that human supervisory control of power Systems will become more complex in the near future for a number of reasons. The European Union for the Co-ordination of Transmission of Electricity (UCTE) has remarked that although the interconnected Systems of power transmission networks has been developed over the years with the main goal of providing secure power supply through common use of reserve capacities and the optimization of the use of energy resources, today's market dynamics imposing a high level of cross-border exchanges is 'out of the scope of the
VOLTAGE AND POWER LOSS CONTROL IN DISTRIBUTION SYSTEM USING UPFC
Yuan, Wei; TANG, Aihong; ZHANG, Xiaocheng; Wang, Shaorong
2012-01-01
Abstract: A simplified loop distribution system is taken as the object and the main reasons leading to the power loss in the feeder are analysed in this paper. According to the natural power distribution theory of the loop systems, the minimum power distribution in the loop power system is deduced through the extremism method. Thinking about the power control function of the unified power flow controller, the control system for the series side of the unified power flow controller is designed ...
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.
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.
Beatriz Machado Fontes; Bruno Machado Fontes; Elaine Castro
2011-01-01
PURPOSE: To compare the achieved refractive outcomes of patients undergoing cataract surgery with intraocular lens (IOL) power calculation performed by conventional immersion ultrasound (US) or partial coherence interferometry (PCI). METHODS: Prospective, comparative case series. Patients undergoing cataract surgery were randomly divided in two groups with regard to the IOL power calculation method. Group 1 had calculations performed by PCI (IOL Master; Carl Zeiss Meditec), while US was used ...
Network integration of distributed power generation
Dondi, Peter; Bayoumi, Deia; Haederli, Christoph; Julian, Danny; Suter, Marco
The world-wide move to deregulation of the electricity and other energy markets, concerns about the environment, and advances in renewable and high efficiency technologies has led to major emphasis being placed on the use of small power generation units in a variety of forms. The paper reviews the position of distributed generation (DG, as these small units are called in comparison with central power plants) with respect to the installation and interconnection of such units with the classical grid infrastructure. In particular, the status of technical standards both in Europe and USA, possible ways to improve the interconnection situation, and also the need for decisions that provide a satisfactory position for the network operator (who remains responsible for the grid, its operation, maintenance and investment plans) are addressed.
International Nuclear Information System (INIS)
The nuclear safety analysis of spent fuel storages taking into account fuel burnup should allow for burnup distribution along the height of the assembly. We propose a method based on an analysis of the axial burnup profiles of spent fuel assemblies. This method can be used in nuclear safety justification of spent fuel management and storage systems
Distributed power generation using biogas fuelled microturbines
International Nuclear Information System (INIS)
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
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.
High power distributed x-ray source
Frutschy, Kris; Neculaes, Bogdan; Inzinna, Lou; Caiafa, Antonio; Reynolds, Joe; Zou, Yun; Zhang, Xi; Gunturi, Satish; Cao, Yang; Waters, Bill; Wagner, Dave; De Man, Bruno; McDevitt, Dan; Roffers, Rick; Lounsberry, Brian; Pelc, Norbert J.
2010-04-01
This paper summarizes the development of a distributed x-ray source with up to 60kW demonstrated instantaneous power. Component integration and test results are shown for the dispenser cathode electron gun, fast switching controls, high voltage stand-off insulator, brazed anode, and vacuum system. The current multisource prototype has been operated for over 100 hours without failure, and additional testing is needed to discover the limiting component. Example focal spot measurements and x-ray radiographs are included. Lastly, future development opportunities are highlighted.
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.
Applicability of the limiting cases for axial annular flow of power-law fluids
Czech Academy of Sciences Publication Activity Database
Filip, Petr; David, Jiří
Fukuoka: WSEAS Press, 2013 - ( Fujita , H.; Tuba, M.; Sasaki, J.), s. 45-48 ISBN 978-1-61804-177-7. ISSN 1790-5117. [Recent advances in automatic control, modelling and simulation. Morioka City (JP), 23.04.2013-25.04.2013] R&D Projects: GA ČR GA103/09/2066 Institutional support: RVO:67985874 Keywords : annular flow * power-law fluids * poiseuille flow * flow rate * pressure drop Subject RIV: BK - Fluid Dynamics
International Nuclear Information System (INIS)
Modern Monte Carlo computer codes (e.g. MCNP) for neutron transport allow calculation of detailed neutron flux and power distribution in complex geometries with resolution of ∼1 mm. Moreover they enable the calculation of individual particle tracks, scattering and absorption events. With the use of advanced software for 3D visualization (e.g. Amira, Voxler, etc.) one can create and present neutron flux and power distribution in a 'user friendly' way convenient for educational purposes. One can view axial, radial or any other spatial distribution of the neutron flux and power distribution in a nuclear reactor from various perspectives and in various modalities of presentation. By visualizing the distribution of scattering and absorption events and individual particle tracks one can visualize neutron transport parameters (mean free path, diffusion length, macroscopic cross section, up-scattering, thermalization, etc.) from elementary point of view. Most of the people remember better, if they visualize the processes. Therefore the representation of the reactor and neutron transport parameters is a convenient modern educational tool for the (nuclear power plant) operators, nuclear engineers, students and specialists involved in reactor operation and design. The visualization of neutron flux and power distributions in Jozef Stefan Institute TRIGA Mark II research reactor is treated in the paper. The distributions are calculated with MCNP computer code and presented using Amira and Voxler software. The results in the form of figures are presented in the paper together with comments qualitatively explaining the figures. (authors)
International Nuclear Information System (INIS)
The CEGB's post irradiation facility at AEE Winfrith is used routinely to measure rating distributions in Civil AGR stringers by axial fuel pin gamma scanning. Some supplementary data is also obtained by mass spectrometry measurements carried out by the UKAEA. The results are used to assess the accuracies of calculated power distributions, which are of direct safety and economic consequence. A review is given of the measurements and comparisons with predictions, and comments are made on the implications of the results. (author)
Test report light duty utility arm power distribution system (PDS)
International Nuclear Information System (INIS)
The Light Duty Utility Arm (LDUA) Power Distribution System has completed vendor and post-delivery acceptance testing. The Power Distribution System has been found to be acceptable and is now ready for integration with the overall LDUA system
Energy Technology Data Exchange (ETDEWEB)
Torres, L.G.; Zamora, E.R. [Universidad Nacional Autonoma de Mexico, Coyoacan (Mexico). Coordinacion de Ambiental, Intituto de Ingenieria
2002-12-01
Surfactant-oil-water emulsions could have applications in enhanced oil recovery and the bio-desulfurization process applied to crude oil and some fractions. A simple way to prepare oil in water (O/W) emulsions is using a tank and an agitation device. The aim of this work is to propose a technology to prepare surfactant-fuel oil-water emulsions by means of a system involving a tank equipped with baffles, and an agitation device. The employed fuel oil was a high-viscosity fraction, which makes it difficult to handle. Axial, radial, and mixed flow impellers were assessed in the preparation of O/W emulsions, with and without the presence of baffles. Sixteen commercial surfactants were evaluated on the O/W emulsion formation. The effect of the storage temperature on the emulsions stability was assessed. The presence of salt on the surfactant-fuel oil-water emulsion was also investigated. Power vs. Reynolds numbers, extremely important data for the scaling up of the process, were calculated in basis of the power drawn when preparing the emulsions. Total consumption of energy applied to the system, as well as pumping capacity were measured and related to the quality of the O/W emulsions obtained. 21 refs., 9 figs., 4 tabs.
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
Intelligent distributed control for nuclear power plants
International Nuclear Information System (INIS)
This project was initiated in September 1989 as a three year project to develop and demonstrate Intelligent Distributed Control (IDC) for Nuclear Power Plants. There were two primary goals of this research project. The first goal was to combine diagnostics and control to achieve a highly automated power plant as described by M.A. Schultz. The second goal was to apply this research to develop a prototype demonstration on an actual power plant system, the EBR-2 steam plant. Described in this Final (Third Annual) Technical Progress Report is the accomplishment of the project's final milestone, an in-plant intelligent control experiment conducted on April 1, 1993. The development of the experiment included: simulation validation, experiment formulation and final programming, procedure development and approval, and experimental results. Other third year developments summarized in this report are: (1) a theoretical foundation for Reconfigurable Hybrid Supervisory Control, (2) a steam plant diagnostic system, (3) control console design tools and (4) other advanced and intelligent control
Pascu, Maria Teodora; Miclea, Mihai; Epple, Philipp; Delgado, Antonio; DURST, Franz
2013-01-01
In the field of axial flow turbomachines, the two-dimensional cascade model is often used experimentally or numerically to investigate fundamental flow characteristics and overall performance of the impeller. The core of the present work is a design method for axial fan cascades aiming to derive inversely the optimum blade shape based on the requirements of the impeller and not using any predefined aerofoil profiles. While most design strategies based on the aerofoil theory assume constant to...
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...
Galileo spacecraft power management and distribution system
International Nuclear Information System (INIS)
It has been twelve years since two Voyager spacecraft began the direct route to the outer planets. In October 1989 a single Galileo spacecraft started the return to Jupiter. Conceived as a simple Voyager look-alike, the Galileo power management and distribution (PMAD) system has undergone many iterations in configuration. Major changes to the PMAD resulted from dual spun slip ring limitations, variations in launch vehicle thrust capabilities, and launch delays. Lack of an adequate launch vehicle for an interplanetary mission of Galileo's size has resulted in an extremely long flight duration. A Venus-Earth-Earth Gravity Assist (VEEGA) tour, vital to attain the required energy, results in a 6 year trip to Jupiter and its moons. This paper provides a description of the Galileo PMAD and documents the design drivers that established the final as-built hardware
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. ...
International Nuclear Information System (INIS)
X-ray powers on the order of 10 TW over an area of 4.5 mm2 are produced in the axial direction from the compression of a low-density foam target centered within a z-pinch on the Z generator.1 The x rays from this source are used for high-energy--density physics experiments, including the heating of hohlraums for inertial confinements fusion studies.2 In this article, detailed characteristics of this radiation source measured using an upgraded axial-radiation-diagnostic suite3 together with other on- and off-axis diagnostics are summarized and discussed in terms of Eulerian and Lagrangian radiation--magnetohydrodynamic code simulations. The source, characterized here, employs a nested array of 10-mm-long tungsten wires, at radii of 20 and 10 mm, having a total masses of 2 and 1 mg, and wire numbers of 240 and 120, respectively. The target is a 14mg/ccCH2 foam cylinder of 5 mm diameter. The codes take into account the development of the Rayleigh--Taylor instability in the r--z plane, and provide integrated calculations of the implosion together with the x-ray generation. The radiation exiting the imploding target through the 4.5 mm2 aperture is measured primarily by the axial diagnostic suite that now includes diagnostics at an angle of ∼30o to the z axis. The near on-axis diagnostics include: (1) a seven-element filtered silicon-diode array,4 (2) a five-element filtered x-ray diffraction (XRD) array,5 (3) a six-element filtered PCD array,6 (4) a three-element bolometer,7 (5) time-resolved and time-integrating crystal spectrometers, and (6) two fast-framing x-ray pinhole cameras having 11 frames each. The filtered silicon diodes, XRDs, and PCDs are sensitive to 1--200, 140--2300, and 1000--4000 eV x rays, respectively. They (1) establish the magnitude of the prepluse generated during the run in of the imploding wire arrays, (2) measure the Planckian nature of the dominant thermal, and (3) nonthermal component of the emission. The bolometers and XRDs mounted on the
International Nuclear Information System (INIS)
The purpose of this calculation is to develop axial profiles for estimating the axial variation in burnup of a boiling water reactor (BWR) assembly spent nuclear fuel (SNF) given the average burnup of an assembly. A discharged fuel assembly typically exhibits higher burnup in the center and lower burnup at the ends of the assembly. Criticality safety analyses taking credit for SNF burnup must account for axially varying burnup relative to calculations based on uniformly distributed assembly average burnup due to the under-burned tips. Thus, accounting for axially varying burnup in criticality analyses is also referred to as accounting for the ''end effect'' reactivity. The magnitude of the reactivity change due to ''end effect'' is dependent on the initial assembly enrichment, the assembly average burnup, and the particular axial profile characterizing the burnup distribution. The set of bounding axial profiles should incorporate multiple BWR core designs and provide statistical confidence (95 percent confidence that 95 percent of the population is bound by the profile) that end nodes are conservatively represented. The profiles should also conserve the overall burnup of the fuel assembly. More background on BWR axial profiles is provided in Attachment I
Energy Technology Data Exchange (ETDEWEB)
J. Huffer
2004-09-28
The purpose of this calculation is to develop axial profiles for estimating the axial variation in burnup of a boiling water reactor (BWR) assembly spent nuclear fuel (SNF) given the average burnup of an assembly. A discharged fuel assembly typically exhibits higher burnup in the center and lower burnup at the ends of the assembly. Criticality safety analyses taking credit for SNF burnup must account for axially varying burnup relative to calculations based on uniformly distributed assembly average burnup due to the under-burned tips. Thus, accounting for axially varying burnup in criticality analyses is also referred to as accounting for the ''end effect'' reactivity. The magnitude of the reactivity change due to ''end effect'' is dependent on the initial assembly enrichment, the assembly average burnup, and the particular axial profile characterizing the burnup distribution. The set of bounding axial profiles should incorporate multiple BWR core designs and provide statistical confidence (95 percent confidence that 95 percent of the population is bound by the profile) that end nodes are conservatively represented. The profiles should also conserve the overall burnup of the fuel assembly. More background on BWR axial profiles is provided in Attachment I.
Grid Integration of Solar Power into Distribution Systems
Nguyen, Dung
2016-01-01
As solar energy penetration in the power grid increases, challenges arise from the variable nature of solar power. Like any distributed generation source or load, photovoltaic (PV) generation can impact the voltage profile of a distribution feeder, potentially driving the service voltage outside of acceptable ranges. However, distributed energy resources can also bring great opportunities to improve power quality and cost effectiveness of the current power grid. In this dissertation, we will ...
Autonomous Active and Reactive Power Distribution Strategy in Islanded Microgrids
Wu, Dan; Tang, Fen; Guerrero, Josep M.; Vasquez, Juan Carlos; Chen, Guoliang; Sun, Libing
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 (RES) units regulate different active power, the proposed reactive power distribution is adaptively controlled according to the active power distribution among energy storage systems (ESS) and RES un...
Cascade Failures from Distributed Generation in Power Grids
Scala, Antonio; Pahwa, Sakshi; Scoglio, Caterina
2012-01-01
Power grids are nowadays experiencing a transformation due to the introduction of Distributed Generation based on Renewable Sources. At difference with classical Distributed Generation, where local power sources mitigate anomalous user consumption peaks, Renewable Sources introduce in the grid intrinsically erratic power inputs. By introducing a simple schematic (but realistic) model for power grids with stochastic distributed generation, we study the effects of erratic sources on the robustn...
Institute of Scientific and Technical Information of China (English)
WANG Yan; CUI Hai-qing; YANG Yuan-jian; GUO Jun-hui; LI Nan
2006-01-01
In this article, the governing equations for the unsteady flow of viscoelastic fluid in the eccentric annulus with the inner cylinder reciprocating axially and the expression of the pressure distribution on the wall of the inner cylinder of the annulus are established and derived, respectively, under the bipolar coordinate system.The equations and the expression are solved and calculated numerically using the finite difference method, respectively.The curves of the pressure distribution on the wall of the inner cylinder of the aqueous solution of Hydrolyzed Polyacrylamide (HPAM) are plotted and the influences of annular eccentricity, stroke, and stroke frequency on the pressure distribution are analyzed.
Ya, W.; Hernández-Sánchez, J.F.; Pathiraj, B.; Huis in 't Veld, A.J.
2013-01-01
The effects of powder stream when using different feeding nozzles on the attenuation of the laser power were investigated theoretically and experimentally. The powder streams were recorded with a high speed camera. The average velocity of the particles was obtained using standard Particle Image Velo
International Nuclear Information System (INIS)
An important task in ensuring the operational safety of a nuclear power plant with a vessel-type water-cooled, water-moderated reactor is the development of algorithms for controlling power distribution in base-load and load-following regimes. The control strategy must ensure that the form of power distribution is maintained within the permissible limits in the case of situations presenting a nuclear hazard and of xenon fluctuations when there are variations in power output. The task of controlling power distribution can be broken down into an axial problem and a radial-azimuthal problem. For maintenance of the form of axial power distribution an algorithm of optimum fast-action control is proposed; for maintenance of the radial-azimuthal form, an algorithm of optimum (i.e. best) approximation to the given distribution of control. The two control problems are solved by using a single computerized procedure based on mathematical programming. The algorithms are designed for use in computerized control. The paper presents the results of algorithm simulation. The authors propose that in the first stage, activation of the control systems should involve the operator, who can view the sequence of actions on a display screen. (author)
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...... (RES) units regulate different active power, the proposed reactive power distribution is adaptively controlled according to the active power distribution among energy storage systems (ESS) and RES units. The virtual impedance is implemented in order to improve the reactive power sharing in a...... distributed way. Real-time hardware-in-the-loop results are presented to verify the proposed control strategy....
Shan Yang; Xiangqian Tong
2016-01-01
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 inverte...
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.
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.
Point-Focusing Solar-Power Distributed Receivers
Lucas, J. W.
1985-01-01
Two-volume annual report describes development work aimed at achieving large-scale production of modular, point-focusing distributed receivers (PFDR's) for solar-powered generation of electricity or thermal power for industrial use.
Evaluation of population distribution around nuclear power plants
International Nuclear Information System (INIS)
The evaluation methods, regulations and present status of population distribution around the sites for nuclear power plants in several countries are briefly reviewed in this paper. The features of population distribution in our country, especially in the proposed areas for location of nuclear power plants are discussed. The site population grade factor is suggested as an evaluation criterion for calculating, evaluating and comparing population distributions around nuclear power plants, and its corresponding computer program in BASIC is given
Power Quality Investigation of Distribution Networks Embedded Wind Turbines
Elsherif, A.; Fetouh, T.; Shaaban, H
2016-01-01
In recent years a multitude of events have created a new environment for the electric power infrastructure. The presence of small-scale generation near load spots is becoming common especially with the advent of renewable energy sources such as wind power energy. This type of generation is known as distributed generation (DG). The expansion of the distributed generators- (DGs-) based wind energy raises constraints on the distribution networks operation and power quality issues: voltage sag, v...
14 CFR 25.1310 - Power source capacity and distribution.
2010-01-01
... functioning normally. (2) Essential loads, after failure of any one prime mover, power converter, or energy... source of power is required, after any failure or malfunction in any one power supply system... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Power source capacity and distribution....
Microcanonical Foundation for Systems with Power-Law Distributions
Abe, Sumiyoshi; Rajagopal, and A. K.
2000-01-01
Starting from microcanonical basis with the principle of equal a priori probability, it is found that, besides ordinary Boltzmann-Gibbs theory with the exponential distribution, a theory describing systems with power-law distributions can also be derived.
ENHANCED DISTRIBUTED SERVICE MODEL FOR POWER SYSTEM STATE ESTIMATION
V.Gomathi; Ramachandran, V.
2011-01-01
Web services are emerging technologies of choice for implementing distributed service models for performing power system operations such as state estimation of power systems in a complete secure, distributed and platform independent environment. The power system applications themselves have been developed in different platforms and language paradigms. Interoperability between power system applications becomes a major issue because of the heterogeneous nature. The main aim of this paper is to ...
Energy Technology Data Exchange (ETDEWEB)
Ferrouk, M. [Laboratoire du Genie Physique des Hydrocarbures, University of Boumerdes, Boumerdes 35000 (Algeria)], E-mail: m_ferrouk@yahoo.fr; Aissani, S. [Laboratoire du Genie Physique des Hydrocarbures, University of Boumerdes, Boumerdes 35000 (Algeria); D' Auria, F.; DelNevo, A.; Salah, A. Bousbia [Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione, Universita di Pisa (Italy)
2008-10-15
The present article covers the evaluation of the performance of twelve critical heat flux methods/correlations published in the open literature. The study concerns the simulation of an axially non-uniform heat flux distribution with the RELAP5 computer code in a single boiling water reactor channel benchmark problem. The nodalization scheme employed for the considered particular geometry, as modelled in RELAP5 code, is described. For this purpose a review of critical heat flux models/correlations applicable to non-uniform axial heat profile is provided. Simulation results using the RELAP5 code and those obtained from our computer program, based on three type predictions methods such as local conditions, F-factor and boiling length average approaches were compared.
International Nuclear Information System (INIS)
The present article covers the evaluation of the performance of twelve critical heat flux methods/correlations published in the open literature. The study concerns the simulation of an axially non-uniform heat flux distribution with the RELAP5 computer code in a single boiling water reactor channel benchmark problem. The nodalization scheme employed for the considered particular geometry, as modelled in RELAP5 code, is described. For this purpose a review of critical heat flux models/correlations applicable to non-uniform axial heat profile is provided. Simulation results using the RELAP5 code and those obtained from our computer program, based on three type predictions methods such as local conditions, F-factor and boiling length average approaches were compared
Eriksson, Stefanie; Lasič, Samo; Nilsson, Markus; Westin, Carl-Fredrik; Topgaard, Daniel
2015-03-14
We introduce a nuclear magnetic resonance method for quantifying the shape of axially symmetric microscopic diffusion tensors in terms of a new diffusion anisotropy metric, DΔ, which has unique values for oblate, spherical, and prolate tensor shapes. The pulse sequence includes a series of equal-amplitude magnetic field gradient pulse pairs, the directions of which are tailored to give an axially symmetric diffusion-encoding tensor b with variable anisotropy bΔ. Averaging of data acquired for a range of orientations of the symmetry axis of the tensor b renders the method insensitive to the orientation distribution function of the microscopic diffusion tensors. Proof-of-principle experiments are performed on water in polydomain lyotropic liquid crystals with geometries that give rise to microscopic diffusion tensors with oblate, spherical, and prolate shapes. The method could be useful for characterizing the geometry of fluid-filled compartments in porous solids, soft matter, and biological tissues. PMID:25770532
Energy Technology Data Exchange (ETDEWEB)
Eriksson, Stefanie; Topgaard, Daniel, E-mail: daniel.topgaard@fkem1.lu.se [Division of Physical Chemistry, Department of Chemistry, Lund University, Lund (Sweden); Lasič, Samo [CR Development AB, Lund (Sweden); Nilsson, Markus [Lund University Bioimaging Center, Lund University, Lund (Sweden); Westin, Carl-Fredrik [Department of Radiology, BWH, Harvard Medical School, Boston, Massachusetts MA 02215 (United States); Department of Biomedical Engineering, Medical Informatics, Linköping University, Linköping (Sweden)
2015-03-14
We introduce a nuclear magnetic resonance method for quantifying the shape of axially symmetric microscopic diffusion tensors in terms of a new diffusion anisotropy metric, D{sub Δ}, which has unique values for oblate, spherical, and prolate tensor shapes. The pulse sequence includes a series of equal-amplitude magnetic field gradient pulse pairs, the directions of which are tailored to give an axially symmetric diffusion-encoding tensor b with variable anisotropy b{sub Δ}. Averaging of data acquired for a range of orientations of the symmetry axis of the tensor b renders the method insensitive to the orientation distribution function of the microscopic diffusion tensors. Proof-of-principle experiments are performed on water in polydomain lyotropic liquid crystals with geometries that give rise to microscopic diffusion tensors with oblate, spherical, and prolate shapes. The method could be useful for characterizing the geometry of fluid-filled compartments in porous solids, soft matter, and biological tissues.
Mechanoluminescent Film Sensor for Visualizing Ultrasonic Power Distribution
International Nuclear Information System (INIS)
The measurement of the ultrasonic output power emission from transducers is a very important subject because strong ultrasonic power may be harmful to human health during medical diagnosis and therapy. Conventional techniques for measuring ultrasonic power such as radiation force balance method and calorimetry method provides no information on power distribution, laser interferometry method is very expensive and time-consuming. We have demonstrated in previous research that the mechanoluminescent (ML) film can be used as a sensor for visualizing the ultrasonic power distribution of a transducer with a frequency of 20 MHz. In this research, the ultrasonic power distribution of a transducer with a frequency of 6 MHz was also visualized. The results suggest that this method can be used for visualizing the ultrasonic power distribution of transducers with a wide range of frequency.
Calculation of power distributions for experimental bundles in the NRU loops
International Nuclear Information System (INIS)
The NRU reactor is a large D2O tank filled with many different kinds of experimental and isotope-producing fuel and absorber assemblies in a vertical orientation. Some of the most important facilities are closed H2O loops, in which advanced CANDU fuel concepts can be irradiated in CANDU bundle formats. Six bundles are arranged linearly in a fuel string assembly, which can be installed in a loop test section. Each bundle can be different, and can contain different types of fuel in each ring of elements, so that different fuel concepts and power histories can be run in the same irradiation. The most important piece of information needed to design these irradiations and interpret the PIE results is the power history that each fuel segment experiences during irradiation. The initial power distribution under nominal full reactor power conditions must be calculated to determine if experimental requirements and thermalhydraulic limits can be met. The expected power variation during irradiation must also be known. Following irradiation, the actual power history experienced by each fuel segment must be calculated, to help assess fuel performance. Since only the total loop power-to-coolant is measured directly, it must be broken down into the fission powers of all the different fuel types, elements and segments that were irradiated together. This paper presents a review of the method currently used to achieve this devolution. It involves the use of the 2-D neutron transport code WIMS-AECL to determine the fission power distribution through each type of fuel bundle in the loop string as a function of burnup, and an estimate of the axial thermal flux shape in the moderator outside of the loop. These are input to an accounting code, BURFEL, which uses them to calculate the initial relative powers in all fuel segments in the loop, and sums them to the total loop power. In predictive mode, this is renormalized to the expected loop power at full reactor power, calculated
Wang, Guiji; Chen, Xuemiao; Cai, Jintao; Zhang, Xuping; Chong, Tao; Luo, Binqiang; Zhao, Jianheng; Sun, Chengwei; Tan, Fuli; Liu, Cangli; Wu, Gang
2016-06-01
A high current pulsed power generator CQ-3-MMAF (Multi-Modules Assembly Facility, MMAF) was developed for material dynamics experiments under ramp wave and shock loadings at the Institute of Fluid Physics (IFP), which can deliver 3 MA peak current to a strip-line load. The rise time of the current is 470 ns (10%-90%). Different from the previous CQ-4 at IFP, the CQ-3-MMAF energy is transmitted by hundreds of co-axial high voltage cables with a low impedance of 18.6 mΩ and low loss, and then hundreds of cables are reduced and converted to tens of cables into a vacuum chamber by a cable connector, and connected with a pair of parallel metallic plates insulated by Kapton films. It is composed of 32 capacitor and switch modules in parallel. The electrical parameters in short circuit are with a capacitance of 19.2 μF, an inductance of 11.7 nH, a resistance of 4.3 mΩ, and working charging voltage of 60 kV-90 kV. It can be run safely and stable when charged from 60 kV to 90 kV. The vacuum of loading chamber can be up to 10-2 Pa, and the current waveforms can be shaped by discharging in time sequences of four groups of capacitor and switch modules. CQ-3-MMAF is an adaptive machine with lower maintenance because of its modularization design. The COMSOL Multi-physics® code is used to optimize the structure of some key components and calculate their structural inductance for designs, such as gas switches and cable connectors. Some ramp wave loading experiments were conducted to check and examine the performances of CQ-3-MMAF. Two copper flyer plates were accelerated to about 3.5 km/s in one shot when the working voltage was charged to 70 kV. The velocity histories agree very well. The dynamic experiments of some polymer bonded explosives and phase transition of tin under ramp wave loadings were also conducted. The experimental data show that CQ-3-MMAF can be used to do material dynamics experiments in high rate and low cost shots. Based on this design concept, the peak
Power-law distribution of pressure fluctuations in multiphase flow
Gheorghiu, S.; J.R. van Ommen; Coppens, M.-O.
2003-01-01
The power-law distribution of pressure fluctuation in multiphase flow was discussed. It was found that the probability density function exhibited a power-law drop-off and was well represented by a Tsallis distribution. The analysis showed that the Tsallis statistics arised as a result of bubble polydispersity, rather than system nonextensivity.
Operation analysis of distribution feeders with wind power generation
Energy Technology Data Exchange (ETDEWEB)
Tsai, C.T.; Chen, C.S.; Lee, Y.D. [National Sun Yat-sen Univ., Kaohsiung, Taiwan (China). Dept. of Electrical Engineering; Hsu, C.T. [Southern Taiwan Univ., Tainan, Taiwan (China). Dept. of Electrical Engineering
2008-07-01
The government of Taiwan aims to increase the percent of renewable power generation to 10 per cent of total generation capacity, or 5139 MW, by 2010. This study explored the impact of wind power generation to the distribution systems. In particular, a practical distribution feeder from the Taiwan Power Company (TPC) was used for a computer simulation of a wind powered micro-grid system. For the normal operation of the test feeder, the system voltage variation was derived by considering the daily load profile of test feeder with wind power generation. For the permanent fault in the distribution system, the load shedding scheme was developed for the islanding micro-grid so that stable operation could be restored with the proper pitch angle control for the wind power generator. The seasonal wind power generated by wind turbines was calculated by applying the exponential rate and Weibull possibility distribution model according to the actual minutely wind speed data from the Hengchun area in Taiwan. The mean value and standard deviation of seasonal wind power output were determined for the design of the load shedding scheme when the distribution feeder had been isolated for the islanding operation. For a permanent fault at the outlet of the test feeder, the islanding operation of the isolated power system was formulated after the feeder circuit breaker was tripped. Following 3 stages of load shedding and pitch angle control, the micro-grid stabilized to maintain the power service at critical loads in the distribution feeder. 7 refs., 17 figs.
A Generalization of the Power Law Distribution with Nonlinear Exponent
Prieto, Faustino; Sarabia, José María
2016-01-01
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 nonlinear function which depends on data and two parameters. Then, we provide some basic prope...
On Bivariate Generalized Exponential-Power Series Class of Distributions
Jafari, Ali Akbar; Roozegar, Rasool
2015-01-01
In this paper, we introduce a new class of bivariate distributions by compounding the bivariate generalized exponential and power-series distributions. This new class contains some new sub-models such as the bivariate generalized exponential distribution, the bivariate generalized exponential-poisson, -logarithmic, -binomial and -negative binomial distributions. We derive different properties of the new class of distributions. The EM algorithm is used to determine the maximum likelihood estim...
Energy Technology Data Exchange (ETDEWEB)
Rivera, Fernando F. [Departamento de Quimica, Universidad Autonoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, C.P. 09340, Mexico, D.F. (Mexico); Cruz-Diaz, Martin R., E-mail: mcruz@tese.edu.m [Division de Quimica y Bioquimica, Tecnologico de Estudios Superiores de Ecatepec, Av. Tecnologico S/N Esq. Av. Hank Gonzalez, Valle de Anahuac, C.P. 55120, Ecatepec, Edo. de Mex (Mexico); Rivero, Eligio P. [Departamento de Ingenieria y Tecnologia, Universidad Nacional Autonoma de Mexico, Facultad de Estudios Superiores Cuautitlan, Av. Primero de Mayo, Cuautitlan Izcalli, C.P. 54740, Edo. de Mex (Mexico); Gonzalez, Ignacio [Departamento de Quimica, Universidad Autonoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, C.P. 09340, Mexico, D.F. (Mexico)
2010-12-15
The liquid phase mixing flow pattern at low (20 < Re < 120) and intermediate liquid flow rate (120 < Re < 400) was studied by means of residence time distribution (RTD) experimental curve in an up-flow Filter Press electrochemical reactor (FM01-LC) bench scale. For this purpose, a plastic turbulence promoter was used with stainless-steel and platinised titanium structural meshes as electrodes in channel configuration. To visualize and determine the mixing flow pattern in the liquid phase, the stimulus-response technique was employed using dextran blue (D{sub M} = 1.058 x 10{sup -11} m{sup 2} s{sup -1}, 25 {sup o}C, in water) as model tracer. A theoretical analysis and approximation RTD experimental curves with axial dispersion model (ADM) and plug dispersion exchange model (PDE), with 'closed-closed vessel' boundary conditions were used in order to establish a better approximation of the axial dispersion, stagnant zones, channelling and by-pass (preference flow) effects present at low and intermediate Re. RTD curves show that the liquid flow pattern in the FM01-LC deviates considerably from axial dispersion model at low Re, where the FM01-LC exhibits large channelling, stagnant zones, and dead zone. The PDE model represents fairly this deviation from ideal flow (less dead zone).
Camacho Santiago, Antonio; Castilla Fernández, Miguel; Miret Tomàs, Jaume; Matas Alcalá, José; Guzmán Solà, Ramon; de Sousa Pérez, Óscar; Martí Colom, Pau; García de Vicuña Muñoz de la Nava, José Luis
2013-01-01
Unbalanced voltages in three-phase power systems is a common perturbation propagated along the grid. Distributed Generation plants have gained widespread attention due to their capability to improve power quality in a distributed manner, including voltage unbalance mitigation. A conventional control strategy to command power plants during balanced grid voltages, is the use of power factor to inject/absorb reactive power depending on grid conditions. Advanced control strategies during unbalanc...
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
Energy cost saving strategies in distributed power networks
Tcheukam Alain; Tembine Hamidou
2016-01-01
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...
Electric Transport Traction Power Supply System With Distributed Energy Sources
Abramov, E. Y.; Schurov, N. I.; Rozhkova, M. V.
2016-04-01
The paper states the problem of traction substation (TSS) leveling of daily-load curve for urban electric transport. The circuit of traction power supply system (TPSS) with distributed autonomous energy source (AES) based on photovoltaic (PV) and energy storage (ES) units is submitted here. The distribution algorithm of power flow for the daily traction load curve leveling is also introduced in this paper. In addition, it illustrates the implemented experiment model of power supply system.
Automation of Space Station module power management and distribution system
Bechtel, Robert; Weeks, Dave; Walls, Bryan
1990-01-01
Viewgraphs on automation of space station module (SSM) power management and distribution (PMAD) system are presented. Topics covered include: reasons for power system automation; SSM/PMAD approach to automation; SSM/PMAD test bed; SSM/PMAD topology; functional partitioning; SSM/PMAD control; rack level autonomy; FRAMES AI system; and future technology needs for power system automation.
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.
Local control of reactive power by distributed photovoltaic generators
Energy Technology Data Exchange (ETDEWEB)
Chertkov, Michael [Los Alamos National Laboratory; Turitsyn, Konstantin [Los Alamos National Laboratory; Sulc, Petr [Los Alamos National Laboratory; Backhaus, Scott [Los Alamos National Laboratory
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 real power generated by the PVs. Using one adjustable parameter per circuit, we balance the requirements on power quality and desire to minimize thermal losses. Numerical analysis of two exemplary systems, with comparable total PV generation albeit a different spatial distribution, show how to adjust the optimization parameter depending on the goal. Overall, this local scheme shows excellent performance; it's capable of guaranteeing acceptable power quality and achieving significant saving in thermal losses in various situations even when the renewable generation in excess of the circuit own load, i.e. feeding power back to the higher-level system.
Garanina, O. S.; Romanovsky, M. Yu.
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 c...
Multi-Objective Reactive Power Optimization of Distribution Network with Distributed Generation
Zhao Hui; Luan Zhaowen; Guo Sixin; Han Chunpeng
2016-01-01
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...
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.
Temperature field downstream of an heated bundle mock-up results for different power distribution
International Nuclear Information System (INIS)
The aim of these peculiar experiments performed on the ML4 loop in ISPRA is to evaluate the characteristics of the temperature field over a length of 20 to 30 dias downstream of a rod bundle for different temperatures profiles at the bundle outlet. The final purpose of this work will be to establish either directly or through models whether it is possible or not to detect subassembly failures using suitable of the subassembly outlet temperature signal. 15 hours of digital and analog recording were taped for five different power distributions in the bundle. The total power dissipation remained constant during the whole run. Two flow rates and seven axial location were investigated. It is shown that the different temperature profiles produce slight differences in the variance and skewness of the temperature signal measured along the axis of the pipe over 20 dias
Difference between measured and predicted axial offset at NPP Krsko
International Nuclear Information System (INIS)
At NPP Krsko axial power distribution is monitored through periodic measurements of the AO (axial offset). AO represents the normalized power difference between top and bottom of the core. Within the core design process predicted values of axial offset (P-AO) for the entire core lifetime are calculated. During the core performance surveillance measured AO (M-AO) is compared to the predicted value. Measured vs. predicted axial offset difference (D-AO) of +3% at hot-full-power (HFP) steady-state core conditions is considered to be within measurement and design tolerances. During the last two 18 months cycles increase in the D-AO above 3 % was experienced for limited period of time at NPP Krsko - in cycle 22 for more than 90 EFPD (Effective Full Power Days). For such deviation evaluation has to be performed to confirm that reload safety evaluation and analysis of the core has not been impacted. Root cause analysis was performed afterwards and it was classified as a core design computer code deficiency. Precisely, inadequate axial actinides treatment in the computer code contributed to the observed axial offset difference. (author)
The role of power for distributive fairness
Rode, Julian; Le Menestrel, Marc
2007-01-01
We employ an experimental labour setting to study fairness in the division of gains from productive activity. The focus is on the impact of power structures on allocation decisions and on fairness perceptions. Two types of actors are involved in generating a gain, but only one contributes actively by completing a real-effort task. In three treatments, decision power to divide the gain is assigned (1) to the inactive, (2) jointly to the inactive and the active, and (3) to the active. Results s...
Comparing Different Fault Identification Algorithms in Distributed Power System
Alkaabi, Salim
A power system is a huge complex system that delivers the electrical power from the generation units to the consumers. As the demand for electrical power increases, distributed power generation was introduced to the power system. Faults may occur in the power system at any time in different locations. These faults cause a huge damage to the system as they might lead to full failure of the power system. Using distributed generation in the power system made it even harder to identify the location of the faults in the system. The main objective of this work is to test the different fault location identification algorithms while tested on a power system with the different amount of power injected using distributed generators. As faults may lead the system to full failure, this is an important area for research. In this thesis different fault location identification algorithms have been tested and compared while the different amount of power is injected from distributed generators. The algorithms were tested on IEEE 34 node test feeder using MATLAB and the results were compared to find when these algorithms might fail and the reliability of these methods.
Harnessing computational power: Distributed combinator evaluation
International Nuclear Information System (INIS)
Much interest has been generated by the notion of combinator graph reduction as a mechanism for the implementation of functional languages. An effort is currently in progress at Los Alamos National Laboratory, in collaboration with Yale University, to develop a testbed distributed implementation of a functional language based on this concept. The overall goal is to facilitate the exploitation of implicit parallelism; within this framework, the authors intend to use this testbed to evaluate the utility of strategies for combinator graph reduction in a distributed computing system
van, Ngoc Huynh; Lee, Jae-Hyun; Whang, Dongmok; Kang, Dae Joon
2016-06-01
We have successfully synthesized axially doped p- and n-type regions on a single Si nanowire (NW). Diodes and complementary metal-oxide-semiconductor (CMOS) inverter devices using single axial p- and n-channel Si NW field-effect transistors (FETs) were fabricated. We show that the threshold voltages of both p- and n-channel Si NW FETs can be lowered to nearly zero by effectively controlling the doping concentration. Because of the high performance of the p- and n-type Si NW channel FETs, especially with regard to the low threshold voltage, the fabricated NW CMOS inverters have a low operating voltage (DOI: 10.1039/c6nr01040g
Cascade Failures from Distributed Generation in Power Grids
Scala, Antonio; Scoglio, Caterina
2012-01-01
Power grids are nowadays experiencing a transformation due to the introduction of Distributed Generation based on Renewable Sources. At difference with classical Distributed Generation, where local power sources mitigate anomalous user consumption peaks, Renewable Sources introduce in the grid intrinsically erratic power inputs. By introducing a simple schematic (but realistic) model for power grids with stochastic distributed generation, we study the effects of erratic sources on the robustness of several IEEE power grid test networks with up to 2000 buses. We find that increasing the penetration of erratic sources causes the grid to fail with a sharp transition. We compare such results with the case of failures caused by the natural increasing power demand.
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...
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.
Distributed digital control in nuclear power generation
International Nuclear Information System (INIS)
Regulation using microprocessors offers new possibilities to distributed system designers. Sophisticated algorithms including process simulation enable the system to be adapted to dead time and long time constants. Redundant boards increase reliability and colour CRT screen information displays enable more fully centralised control
Performance parameters of electric power distribution
International Nuclear Information System (INIS)
The aspects referring to the evaluation of distribution system reliability are presented: consumers, companies and regulator institutes. The different strategies for fixing of probabilistic criterions of performance are mentioned, including the economic valorization of continuity restriction of electric supply. (C.G.C.)
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
Solar concentrators with adjustable power density distributions
Energy Technology Data Exchange (ETDEWEB)
Kleinwaechter, J.
1977-09-01
Solar concentrators are described which provide given power density in the absorber. According to the invention, 'semi-optical' lenses and mirrors are used to concentrate the incident solar radiation; these elements image the solar disk not as a point but as an area of constant illumination intensity on the absorber. This is achieved by a functional locus-dependecy of refraction and reflection. For mirror concentration, a differential equation is given which satisfies this functional dependency.
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.
Benchmark calculations of power distribution within assemblies
International Nuclear Information System (INIS)
The main objective of this Benchmark is to compare different techniques for fine flux prediction based upon coarse mesh diffusion or transport calculations. We proposed 5 ''core'' configurations including different assembly types (17 x 17 pins, ''uranium'', ''absorber'' or ''MOX'' assemblies), with different boundary conditions. The specification required results in terms of reactivity, pin by pin fluxes and production rate distributions. The proposal for these Benchmark calculations was made by J.C. LEFEBVRE, J. MONDOT, J.P. WEST and the specification (with nuclear data, assembly types, core configurations for 2D geometry and results presentation) was distributed to correspondents of the OECD Nuclear Energy Agency. 11 countries and 19 companies answered the exercise proposed by this Benchmark. Heterogeneous calculations and homogeneous calculations were made. Various methods were used to produce the results: diffusion (finite differences, nodal...), transport (Pij, Sn, Monte Carlo). This report presents an analysis and intercomparisons of all the results received
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...... different cases are studied to solve power system constraints, improve power system small signal stability and power system transient stability by deciding an appropriate electricity price. An optimal operation strategy for a battery energy storage system (BESS) in relation to the electricity price in order...
Energy Technology Data Exchange (ETDEWEB)
Kallio, S. [Aabo Akademi, Turku (Finland). Inst. of Heat Engineering
1997-10-01
The project has concentrated on the study of the parameters affecting the drag correlations by examining the behaviour of the axial density profiles and especially the steady-state regions in different flow conditions both experimentally and theoretically. The empirical data analysed in this work is collected from hot conditions in a CFB pilot scale combustor. The data consists of pressure profiles and other macroscopic measurements from different flow conditions. In the analysis of the data and in the modelling work empirical methods such as neural network modelling have been used. The results show that the drag correlations written for cold conditions can be adapted to hot conditions by taking into account the change in the terminal velocity of a single particle. (orig.)
Optimization of Electric Power Distribution Using Hybrid Simulated Annealing Approach
Walid Ahmed; Alaa F. Sheta
2008-01-01
The key goal of electric power distribution companies is to provide a high quality of service with a low cost of operation. The growing customer needs requires a re-distribution of the Power over various nodes of the Distributed Generation (DG) facilitates. The re-distribution might cause over load on various parts of the networks which if not correctly optimized might increase the cost of maintenance and affect the overall network reliability. This is why it is urgently requited to find a me...
Optimization of Electric Power Distribution Using Hybrid Simulated Annealing Approach
Directory of Open Access Journals (Sweden)
Walid Ahmed
2008-01-01
Full Text Available The key goal of electric power distribution companies is to provide a high quality of service with a low cost of operation. The growing customer needs requires a re-distribution of the Power over various nodes of the Distributed Generation (DG facilitates. The re-distribution might cause over load on various parts of the networks which if not correctly optimized might increase the cost of maintenance and affect the overall network reliability. This is why it is urgently requited to find a methodology that can effectively provide a schema for re-distribution of the power and achieve both customers and power companies contracting objectives. In this paper, we explore our new proposed idea of using a simulated annealing based local search technique to provide an efficient power load distribution for distributed generation network. On doing this, we will apply our approach on the famous IEEE14 and IEEE30 power systems as two test cases. The developed results show the significant of the proposed approach.
Description of a 20 Kilohertz power distribution system
Hansen, I. G.
1986-01-01
A single phase, 440 VRMS, 20 kHz power distribution system with a regulated sinusoidal wave form is discussed. A single phase power system minimizes the wiring, sensing, and control complexities required in a multi-sourced redundantly distributed power system. The single phase addresses only the distribution link; mulitphase lower frequency inputs and outputs accommodation techniques are described. While the 440 V operating potential was initially selected for aircraft operating below 50,000 ft, this potential also appears suitable for space power systems. This voltage choice recognizes a reasonable upper limit for semiconductor ratings, yet will direct synthesis of 220 V, 3 power. A 20 kHz operating frequency was selected to be above the range of audibility, minimize the weight of reactive components, yet allow the construction of single power stages of 25 to 30 kW. The regulated sinusoidal distribution system has several advantages. With a regulated voltage, most ac/dc conversions involve rather simple transformer rectifier applications. A sinusoidal distribution system, when used in conjunction with zero crossing switching, represents a minimal source of EMI. The present state of 20 kHz power technology includes computer controls of voltage and/or frequency, low inductance cable, current limiting circuit protection, bi-directional power flow, and motor/generator operating using standard induction machines. A status update and description of each of these items and their significance is presented.
Calculated CIM Power Distributions for Coil Design
International Nuclear Information System (INIS)
Excessive bed expansion and material expulsion have occurred during experiments with the 3-inch diameter Cylindrical Induction Melter (CIM). Both events were attributed in part to the high power density in the bottom of the melter and the correspondingly high temperatures there. It is believed that the high temperatures resulted in the generation of gasses at the bottom of the bed which could not escape. The gasses released during heating and the response of the bed to gas evolution depend upon the composition of the bed
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......) reference seven-layer model of communication systems, and the main communication technologies and protocols on each corresponding layer are introduced. Some newly developed communication techniques, like Ethernet, are discussed with reference to the possible applications in distributed power system. 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...
Energy loss analysis of an integrated space power distribution system
Kankam, M. David; Ribeiro, P. F.
1992-01-01
The results of studies related to conceptual topologies of an integrated utility-like space power system are described. The system topologies are comparatively analyzed by considering their transmission energy losses as functions of mainly distribution voltage level and load composition. The analysis is expedited by use of a Distribution System Analysis and Simulation (DSAS) software. This recently developed computer program by the Electric Power Research Institute (EPRI) uses improved load models to solve the power flow within the system. However, present shortcomings of the software with regard to space applications, and incompletely defined characteristics of a space power system make the results applicable to only the fundamental trends of energy losses of the topologies studied. Accountability, such as included, for the effects of the various parameters on the system performance can constitute part of a planning tool for a space power distribution system.
Distributed Learning Policies for Power Allocation in Multiple Access Channels
Mertikopoulos, Panayotis; Belmega, Elena V.; Moustakas, Aris L.; Lasaulce, Samson
2011-01-01
We analyze the problem of distributed power allocation for orthogonal multiple access channels by considering a continuous non-cooperative game whose strategy space represents the users' distribution of transmission power over the network's channels. When the channels are static, we find that this game admits an exact potential function and this allows us to show that it has a unique equilibrium almost surely. Furthermore, using the game's potential property, we derive a modified version of t...
Power-aware applications for scientific cluster and distributed computing
Abdurachmanov, David; Elmer, Peter; Eulisse, Giulio; Grosso, Paola; Hillegas, Curtis; Holzman, Burt; Janssen, Ruben L.; 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 ...
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.
Robust Optimal Power Distribution for Hyperthermia Cancer Treatment
Shariati, Nafiseh; Zachariah, Dave; Karlsson, Johan; Bengtsson, Mats
2015-01-01
We consider an optimization problem for spatial power distribution generated by an array of transmitting elements. Using ultrasound hyperthermia cancer treatment as a motivating example, the signal design problem consists of optimizing the power distribution across the tumor and healthy tissue regions, respectively. The models used in the optimization problem are, however, invariably subject to errors. deposition as well as inefficient treatment. To combat such unknown model errors, we formul...
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.
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.
Thresholded Power law Size Distributions of Instabilities in Astrophysics
Aschwanden, Markus J.
2015-11-01
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 x0; (3) contamination by an event-unrelated background xb; and (4) truncation effects at the largest events due to a finite system size. These effects can be modeled in the 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 x0 > 0 is positive for a threshold effect, while x0 critical threshold x0. We apply the thresholded power law distribution function to terrestrial, solar (HXRBS, BATSE, RHESSI), and stellar flare (Kepler) data sets. We find that the thresholded power law model provides an adequate fit to most of the observed data. Major advantages of this model are the automated choice of the power law fitting range, diagnostics of background contamination, physical instability thresholds, instrumental detection thresholds, and finite system size limits. When testing self-organized criticality models that predict ideal power laws, we suggest including these natural truncation effects.
A Multi-Functional Power Electronic Converter in Distributed Generation Power Systems
DEFF Research Database (Denmark)
Chen, Zhe; Blaabjerg, Frede; Pedersen, John Kim
This paper presents a power electronic converter which is used as an interface for a distributed generation unit/energy storage device, and also functioned as an active power compensator in a hybrid compensation system. The operation and control of the converter have been described. An example 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...
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...
Impact Study on Power Factor of Electrical Load in Power Distribution System
International Nuclear Information System (INIS)
Low Power Factor of electrical loads cause high current is drawn from power supply. The impact of this circumstance is influenced by impedance of electrical load. Therefore, the key consideration of this study is how impedance of electrical loads influence power factor of electrical loads, and then power distribution as the whole. This study is important to evaluate the right action to mitigate low power factor effectively for electrical energy efficiency purpose. (author)
Waves in plasmas with power-law distributions
International Nuclear Information System (INIS)
Full text: Most theoretical studies of waves in plasmas assume a Maxwellian velocity distribution. However, often plasmas have a power-law distribution, with an excess of superthermal particles. Observations of power-law distributions are common in space, and they are also observed in the laboratory. Such velocity distributions may be modelled by a generalized Lorentzian distribution, often called a kappa-distribution. For high-energy particles this family of distributions has a power-law form, the real-valued parameter kappa allowing for fitting to the actual distribution. While kappa tending to infinity yields the Maxwellian, a low value of kappa describes a strongly accelerated, hard spectrum. Thus a wide range of distributions is represented. In particular it should be noted that observations are often fitted by a distribution with a fairly low value of kappa. A plasma dispersion function for electrostatic waves, introduced by Summers and Thorne for distributions having integer kappa, was generalized to distributions with arbitrary real kappa by Mace and Hellberg, and expressed in terms of a hypergeometric function. This representation allows for ease of application to wave studies. In the limit of kappa tending to infinity, it reduces to the usual Z-function of Fried and Conte. We discuss recent studies of waves in kappa-distribution plasmas, emphasizing in particular the effects of the non-Maxwellian nature of low-kappa distributions. Both dispersion and damping/growth of waves may differ significantly from the behaviour found for Maxwellian plasmas, as observed both in space and laboratory plasmas. In addition to considering electron plasma waves, we describe applications to a laboratory study of electron-acoustic waves and to a satellite-based observation of a whistler instability, using a bi-Lorentzian distribution
Communication Systems and Study Method for Active Distribution Power systems
Wei, Mu; Chen, Zhe
2010-01-01
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) reference seven-layer model of communication systems, and the main communication technologies and protocols on each corresponding layer are introduced. Some newly developed communication techniques, like Et...
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
Evaluation of electric power distribution systems: period 1984/89
International Nuclear Information System (INIS)
The historical evolution of electric power distribution systems in Brazil, during 1984 to 1989 is described, showing the consumer market with the physical expansion of Distribution Networks and the results of quality from the services made by the companies to their clients. (C.G.C.)
Analytical Limit Distributions from Random Power-Law Interactions
Zaid, Irwin; Mizuno, Daisuke
2016-07-01
Nature is full of power-law interactions, e.g., gravity, electrostatics, and hydrodynamics. When sources of such fields are randomly distributed in space, the superposed interaction, which is what we observe, is naively expected to follow a Gauss or Lévy distribution. Here, we present an analytic expression for the actual distributions that converge to novel limits that are in between these already-known limit distributions, depending on physical parameters, such as the concentration of field sources and the size of the probe used to measure the interactions. By comparing with numerical simulations, the origin of non-Gauss and non-Lévy distributions are theoretically articulated.
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.
Chassin, David P.; Donnelly, Matthew K.; Dagle, Jeffery E.
2011-12-06
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.
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.
Population distribution considerations in nuclear power plant siting
International Nuclear Information System (INIS)
The population distribution surrounding a site proposed for a nuclear power plant is an important consideration in the site selection process, and is relevant to both siting and environmental aspects of nuclear power plant siting. In addition, the reactor site criteria specified in 10 CFR Part 100 requires that the surrounding population be given consideration in the siting and design of the facility. Developing methods of analyzing the population distribution characteristics of alternative sites (as discussed in the environmental report for construction of a nuclear power plant) is necessary to arrive at a conclusion regarding the desirability of a proposed site. (U.S.)
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.
Econophysical anchoring of unimodal power-law distributions
International Nuclear Information System (INIS)
The sciences are abundant with size distributions whose densities have a unimodal shape and power-law tails both at zero and at infinity. The quintessential examples of such unimodal and power-law (UPL) distributions are the sizes of income and wealth in human societies. While the tails of UPL distributions are precisely quantified by their corresponding power-law exponents, their bulks are only qualitatively characterized as unimodal. Consequently, different statistical models of UPL distributions exist, the most popular considering lognormal bulks. In this paper we present a general econophysical framework for UPL distributions termed ‘the anchoring method’. This method: (i) universally approximates UPL distributions via three ‘anchors’ set at zero, at infinity, and at an intermediate point between zero and infinity (e.g. the mode); (ii) is highly versatile and broadly applicable; (iii) encompasses the existing statistical models of UPL distributions as special cases; (iv) facilitates the introduction of new statistical models of UPL distributions and (v) yields a socioeconophysical analysis of UPL distributions. (paper)
Effect of Heterogeneity of JSFR Fuel Assemblies to Power Distribution
International Nuclear Information System (INIS)
The Japanese sodium-cooled fast reactor JSFR is an oxide fueled system rated at 1,500 MWe. The core is composed of large fuel assemblies with an inner duct for each assembly. Thus, the assembly heterogeneity is rather strong. The purpose of the present paper is to make clear the effect of the heterogeneity to assembly and core characteristics, especially to power distribution. The inner duct is located at one corner of a hexagonal assembly, and the effect of the location has been investigated. We have compared the power distribution when the inner duct is always located near the core center and/or far from the core center. The power at the core center increased and decreased by ~10%, respectively compared to the case when the inner duct is randomly located. Thus, the location has important effect to power distribution. (author)
Power Generation and Distribution System of Modern Civil Aircraft
Directory of Open Access Journals (Sweden)
Swapnil Srivastava
2014-04-01
Full Text Available As the aircraft industry is moving towards the all electric and More Electric Aircraft (MEA; is the future trend in adopting single power type for driving the non-propulsive aircraft systems; i.e. is the electrical power. The trend in the aircraft industry is to replace hydraulic and pneumatic systems with electrical systems achieving more comfort and monitoring features. The structure of MEA distribution system improves aircraft maintainability, reliability, flight safety and efficiency. Moreover, MEA reduces the emissions of air pollutant gases from aircrafts, which can contribute in significantly solving some of the problems of climate change. However, the MEA puts some challenges on the aircraft electrical system, both in the amount of the required power and the processing and management of this power. MEA electrical distribution systems are mainly in the form of multi-converter power electronic system.
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-integral, proportio......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 in...
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.
Broadening of axial neutron flux difference operating band in Angra I
International Nuclear Information System (INIS)
ANGRA I Technical Specifications requires the axial flux difference to remain within ± 5 percent band, relative to a reference value, for any power level. The reference value is the axial flux difference at a 100% power, all rods (almost) out and equilibrium Xenon distribution. This paper presents the results of several Simulations, performed by FURNAS staff aiming the validation of calculation results against the reload designer's ones. It was also proved that the Axial Flux Difference Operating band can be broadened to ''Ref. +- 6.9% ) without exce eding the limit imposed by the ''envelope-curve''. (author)
An Optimal and Distributed Method for Voltage Regulation in Power Distribution Systems
Zhang, Baosen; Lam, Albert Y. S.; Dominguez-Garcia, Alejandro D.; Tse, David
2012-01-01
This paper addresses the problem of voltage regulation in power distribution networks with deep-penetration of distributed energy resources, 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...
Di Tommaso, Antonino O.; Fabio Genduso; Rosario Miceli; Giuseppe Ricco Galluzzo
2013-01-01
Distributed generation (DG) is deeply changing the existing distribution networks which become very sophisticated and complex incorporating both active and passive equipment. The simplification of their management can be obtained assuming a structure with small networks, namely, microgrids, reproducing, in a smaller scale, the structure of large networks including production, transmission, and distribution of the electrical energy. Power converters in distributed generation systems carry on s...
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.
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...
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.
Population distribution analyses for nuclear power plant siting
International Nuclear Information System (INIS)
The Nuclear Regulatory Commission is in the process of reviewing guidelines and regulations associated with population distribution criteria around nuclear power plant sites. The purpose of this paper is to describe the methodology for calculating population distributions in the US and then evaluating specific population criteria and their effect upon the selection of future nuclear power plant sites. Through the use of computer systems, different alternatives may be evaluated for individual sites or for major regions of the country to determine their restrictiveness on siting nuclear plants. Two types of criteria were used. They involved the analysis of population distributions radially out from each possible site and the study of angular distributions around each site. Results are presented in both tabular and graphic form using national, regional, and site-level computer maps. 5 references, 39 figures, 8 tables
The California power crisis: the role for distributed generation
International Nuclear Information System (INIS)
This article examines the impact of the California power crisis on cogeneration and the on-site generation market, and highlights the plight of independent power generators including cogeneration facilities who have typically long-term contracts with the cash-strapped state electric utilities and have to defer maintenance due to unpaid bills. The move towards distributed generation, the efforts to increase backup diesel-fired generation during blackouts, and the government's efforts to encourage distributed energy are discussed along with the concerns of air quality regulators with on-site generation emissions, and the impact of the California crisis on the future of distributed energy. The growing role of distributed energy in meeting demand and holding down costs is explored, and the expanding market for microturbines is noted
Population distribution analyses for nuclear power plant siting
Energy Technology Data Exchange (ETDEWEB)
Durfee, R.C.; Coleman, P.R.
1983-12-01
The Nuclear Regulatory Commission is in the process of reviewing guidelines and regulations associated with population distribution criteria around nuclear power plant sites. The purpose of this paper is to describe the methodology for calculating population distributions in the US and then evaluating specific population criteria and their effect upon the selection of future nuclear power plant sites. Through the use of computer systems, different alternatives may be evaluated for individual sites or for major regions of the country to determine their restrictiveness on siting nuclear plants. Two types of criteria were used. They involved the analysis of population distributions radially out from each possible site and the study of angular distributions around each site. Results are presented in both tabular and graphic form using national, regional, and site-level computer maps. 5 references, 39 figures, 8 tables.
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.
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 ...
Power distribution from insertion device x-ray sources
International Nuclear Information System (INIS)
Insertion device (ID) synchrotron x-ray sources on present day and next-generation synchrotron facilities have very attractive spectral properties. In addition however, they are capable of producing x-ray beams with large powers and in some cases, unprecedented power densities. An overview of the spatial and frequency distributions of these sources including the effects of synchrotron particle beam emittance is presented
Stability of power systems with large amounts of distributed generation
Knazkins, Valerijs
2004-01-01
This four-part dissertation is essentially concerned with some theoretical aspects of the stability studies of power systems with large penetration levels of distributed generation. In particular, in Parts I and II the main emphasis is placed upon the transient rotor angle and voltage stability. The remaining two parts are devoted to some system-theoretic and practical aspects of identification and modeling of aggregate power system loads, design of auxiliary robust control, and a general qua...
Evolutionary Optimization of Electric Power Distribution Using the Dandelion Code
Jorge Sabattin; Carlos Contreras Bolton; Miguel Arias; Víctor Parada
2012-01-01
Planning primary electric power distribution involves solving an optimization problem using nonlinear components, which makes it difficult to obtain the optimum solution when the problem has dimensions that are found in reality, in terms of both the installation cost and the power loss cost. To tackle this problem, heuristic methods have been used, but even when sacrificing quality, finding the optimum solution still represents a computational challenge. In this paper, we study this problem u...
Contribution to MPC coordination of distributed and power generation systems
Sandoval Moreno, John Anderson
2014-01-01
This thesis is mainly about coordination of distributed systems, with a special attention to multi-energy electric power generation ones. For purposes of optimality, as well as constraint enforcement, Model Predictive Control (MPC) is chosen as the underlying tool, while wind turbines, fuel cells, photovoltaic panels, and hydroelectric plants are mostly considered as power sources to be controlled and coordinated. In the first place, an application of MPC to a micro-grid system is proposed, i...
Power distribution for the ATLAS LAr Trigger Digitizer Board
International Nuclear Information System (INIS)
The R and 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 Point-of-load converters also in presence of high magnetic fields are covered. Devices designed by CERN 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
Power-law distribution in Japanese racetrack betting
Ichinomiya, Takashi
2006-01-01
Gambling is one of the basic economic activities that humans indulge in. An investigation of gambling activities provides deep insights into the economic actions of people and sheds lights on the study of econophysics. In this paper we present an analysis of the distribution of the final odds of the races organized by the Japan Racing Association. The distribution of the final odds $P_o(x)$ indicates a clear power law $P_o(x)\\propto 1/x$, where $x$ represents the final odds. This power law ca...
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.
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.
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...
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 of 5003 nodes. For this model, the Newton load flow model converges in seven iterations. Future work in this direction should allow to build even larger networks.
Disaggregated Bundle Methods for Distributed Market Clearing in Power Networks
Zhang, Yu; Gatsis, Nikolaos; Giannakis, Georgios B.
2013-01-01
A fast distributed approach is developed for the market clearing with large-scale demand response in electric power networks. In addition to conventional supply bids, demand offers from aggregators serving large numbers of residential smart appliances with different energy constraints are incorporated. Leveraging the Lagrangian relaxation based dual decomposition, the resulting optimization problem is decomposed into separate subproblems, and then solved in a distributed fashion by the market...
Power distribution monitoring and control in 500 MWe PHWR
International Nuclear Information System (INIS)
The 500 MWe Indian Pressurized Heavy Water Reactor (PHWR) is expected to be commissioned in a few years. It has a relatively large sized core with complex material distribution in comparison to the currently operating 220 MWe PHWRs. The resulting neutronically loosely coupled system demands continuous control of the core power distribution. This paper gives a brief description and analysis of the reactor monitoring and control system proposed for this reactor. (author). 11 refs, 8 figs, 3 tabs
Space craft thermal thermionic reactors with flat power distribution
International Nuclear Information System (INIS)
The nuclear reactors are potential candidates for energy generation in space missions over longer periods where high power output is required. Among different nuclear energy conversion options, the statical ones, such as thermo-electric or thermionic reactors, are preferable in order to avoid the kinetic disturbances of the space craft and furthermore in order to reduce the failure probabilities to a minimum, caused by lubricants and seals. In the present study, the main parameters of different types of thermal thermionic reactors are discussed which are fueled with U-233 or U-235 and moderated with ZrH1.7 or Beryllium. The investigated thermionic reactors will be layed out to have a constant heat production density on the emitter surface over the space variable, so as to achieve a maximum engineering efficiency with respect to the electrical conversion, nuclear fuel utilization, material damage, thermal and radiation gradients. The power flattening procedure is performed by varying the moderator to fuel ratio, both in axial and radial directions
The electrical power transmission and distribution market in Brazil
International Nuclear Information System (INIS)
Brazil, the largest country in South America, is also the largest consumer of energy with a total installed electrical generating capacity of 68,000 megawatts. Brazil has an estimated value of $2.96 billion invested in electrical power equipment and a sector that is growing at a rate of 4.2 per cent per year. Hydroelectric power accounts for 93 per cent of the total power generation, with thermal generation providing the balance. It is expected that hydroelectric power will decrease to about 80 per cent and thermal power generation will increase by 20 per cent in the next decade. Existing thermal power plants in Brazil are mainly fuel-oil based, followed by coal and then nuclear. The North/Northeast and South/Southeast networks which controlled power transmission in Brazil up until the late 1990s, were recently joined by a 1277 km line forming the North/South interconnection. Despite this, the system does not reach about 100,000 rural communities that must currently rely on unstable stand-alone power generation plants. An new 3638 km long national transmission line is being planned for 2007 to meet the energy needs of these off-grid communities. Electrobras, the Brazilian government's electric power sector holding company, is promoting two programs to expand power distribution and transmission through the country. These programs could provide potential opportunities for Canadian electrical equipment companies. A tariff of 8-18 per cent is levied against all electric power distribution and transmission equipment entering Brazil. Port charges and internal taxes are also applied. refs
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 distribution of family names in Japanese societies
Miyazima, Sasuke; Lee, Youngki; Nagamine, Tomomasa; Miyajima, Hiroaki
2000-04-01
We study the frequency distribution of family names. From a common data base, we count the number of people who share the same family name. This is the size of the family. We find that (i) the total number of different family names in a society scales as a power law of the population, (ii) the total number of family names of the same size decreases as the size increases with a power law and (iii) the relation between size and rank of a family name also shows a power law. These scaling properties are found to be consistent for five different regional communities in Japan.
Economic assessment group on power transmission and distribution networks tariffs
International Nuclear Information System (INIS)
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.)
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.
International Nuclear Information System (INIS)
Modular high temperature gas cooled reactor HTR-PM demonstration plant, designed by INET, Tsinghua University, is being built in Shidaowan, Shandong province, China. HTR-PM adopts pebble bed concept. Like other HTR, to measure or monitor the core power distribution is very important but challenging for HTR-PM, as there is no in-core neutron detectors. There are some proposals to reconstruct the power distribution from the readings of ex-core neutron detectors. One method is harmonic synthesis method. In this paper, improved harmonic synthesis method is proposed and tested to increase the accuracy of the power distribution reconstruction, by using better fundamental harmonic according to different reactor operation conditions. The numerical result shows the improvement in the reconstruction accuracy, contrasting to harmonics' coefficients polynomial expansion method. (author)
International Nuclear Information System (INIS)
A general critical heat flux (CHF) prediction method with a wide applicable range and reasonable accuracy is essential to the thermal-hydraulic design and safety analysis at the conceptual design stage for a new pressurized water reactor (PWR). In this study, the Korea Advanced Institute of Science and Technology (KAIST) liquid sub-layer dryout CHF prediction model for Departure from Nucleate Boiling (DNB) region has been implemented in a sub-channel analysis code, and investigated for the method's possible use in a rod bundle environment with various non-uniform axial power shapes. The KAIST model showed comparable prediction capability to Lin's method for bottom-, center-, and top-peaked heat flux shapes. The KAIST model, without any correction factors or empirical constants, turned out to be suitable to fulfill the needs for a basis of a general CHF prediction method as compared to Lin's method and Westinghouse-3 (W-3) correlation
Directory of Open Access Journals (Sweden)
Abbas A.H.
2016-01-01
Full Text Available A laboratory scale bubbling fluidized bed combustor was designed and fabricated to study the combustion of dewatered poultry sludge at different operational parameters. This paper present a study on the influence of equivalent ratio, secondary to primary air ratio and the fuel feed rate on the temperature distribution along the combustor. The equivalent ratio has been changed between 0.8 to 1.4% under poultry sludge feed rate of 10 kg/h and from 0.8 to 1 under poultry sludge feed rate of 15 kg/h. The secondary to primary air ratio was varied from 0.1 to 0.5 at 0.65 m injection height and 1.25 equivalent ratio. The results showed that these factors had a significant influence on the combustion characteristics of poultry sludge. The temperature distribution along the combustor was found to be strongly dependent on the fuel feed rate and the equivalent ratio and it increased when these two factors increased. However, the secondary air ratio increased the temperature in the lower region of the combustor while no significant effect was observed at the upper region of the combustor. The results suggested that the poultry sludge can be used as a fuel with high thermal combustor efficiency.
Generation of potential/surface density pairs in flat disks Power law distributions
Hure, J -M; Pierens, A
2007-01-01
We report a simple method to generate potential/surface density pairs in flat axially symmetric finite size disks. Potential/surface density pairs consist of a ``homogeneous'' pair (a closed form expression) corresponding to a uniform disk, and a ``residual'' pair. This residual component is converted into an infinite series of integrals over the radial extent of the disk. For a certain class of surface density distributions (like power laws of the radius), this series is fully analytical. The extraction of the homogeneous pair is equivalent to a convergence acceleration technique, in a matematical sense. In the case of power law distributions, the convergence rate of the residual series is shown to be cubic inside the source. As a consequence, very accurate potential values are obtained by low order truncation of the series. At zero order, relative errors on potential values do not exceed a few percent typically, and scale with the order N of truncation as 1/N**3. This method is superior to the classical mul...
Trends in development of in-core monitoring of light water cooled reactor power distribution
International Nuclear Information System (INIS)
Trends and achievements in the development of in-core monitoring of light water cooled reactor power distribution are described. Application of inertialess detectors in control systems of the 1300 MW PWR reactors operating in the load-following regime, various options of the systems, the capabilities and prospects of further improvement are considered. Problems accompanying their application are analysed. Wire and fall-type activation detectors were used in the PWR and BWR reactors at the initial stages of in-core monitoring system development. Later systems with stationary β-emission neutron detectors, with rhodium or vanadium emitters and compton emission neutron detectors with emitters of cobalt or hafnium gained wide application. Gamma thermometer which require no calibration during the operation appear to be new detectors for continuous control in PWRs. However they are intertice and their application does not rid of the necessity to have sensors with minor signal delay in the control system and does not allow one to refuse periodic changes of axial power by mobile detectors, providing for high accuracy and detalization of distributions
International Nuclear Information System (INIS)
An advancement or variety of PWR cores by introducing MOX fuel, burnable poison and so on, increases a heterogeneity in a core or an assembly. For the evaluation of the pin power distribution, the fine mesh flux reconstruction is required with the combination of an assembly calculation and a three dimensional core calculation with coarse mesh, instead of the combination of a two dimensional X-Y core calculation with fine mesh and a one dimensional axial core calculation for the conventional PWR core. The main purpose of the NEANSC benchmark problems entitled 'Power Distribution within Assemblies' is to compare the technique of the fine mesh flux reconstruction based on coarse mesh core calculation. In this report, we examine the validity of the reconstruction technique based on the coarse mesh core calculation using the Spline function, assembly calculation and heterogeneous fine mesh core calculation by built-in programs in the SRAC code using the groupwise Monte Carlo calculation with the GMVP code as reference. (author)
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...... 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...... 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...
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.
Novel DC/DC Converters For High-Power Distributed Power Systems
Francisco Venustiano, Canales Abarca
2003-01-01
One of the requirements for the next generation of power supplies for distributed power systems (DPSs) is to achieve high power density with high efficiency. In the traditional front-end converter based on the two-stage approach for high-power three-phase DPSs, the DC-link voltage coming from the power factor correction (PFC) stage penalizes the second-stage DC/DC converter. This DC/DC converter not only has to meet the characteristics demanded by the load, but also must process energy w...
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.
Negative Influence of Frequency Converters on Power Distribution Network
Directory of Open Access Journals (Sweden)
Martin Pittermann
2006-01-01
Full Text Available This paper deals with low-frequency analysis of the phase current taken by frequency converters from a power distribution network. Problems concerning with characteristic harmonic currents are relatively well-known. Therefore the main emphasis of this work is focused on the investigation of factors which influence arising of non-characteristic and interharmonic current components
Distributed Generation Using Indirect Matrix Converter in Reverse Power Mode
DEFF Research Database (Denmark)
Liu, Xiong; Chiang Loh, Poh; Wang, Peng;
2013-01-01
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...
Using Model Checking for Analyzing Distributed Power Control Problems
DEFF Research Database (Denmark)
Brihaye, Thomas; Jungers, Marc; Lasaulce, Samson; Markey, Nicolas; Oreiby, Ghassan
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...
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.
Institute of Scientific and Technical Information of China (English)
SHI Zongqian; LIU Zhigang; JIA Shenli; SONG Xiaochuan; WANG Lijun
2009-01-01
Effect of the axial magnetic field (AMF) on resisting the constriction of a high-current vacuum arc is studied in this paper. Two typical AMF distributions were investigated, i.e., the traditional bell-shaped AMF, and the saddle-shaped AMF. Experiments were conducted in a detachable vacuum chamber with a rms arc current in the range of 10 kA to 25 kA. The arc column was photographed by a high-speed digital camera with an exposure time of 2 microseconds. The constriction of the vacuum arc was compared by processing the images of the arc column under the two different field configurations and numerically determining the dimensions of the arc column near the electrodes. It was also confirmed that the AMF distribution had a signifcant influence on its effectiveness in resisting arc constriction, Furthermore, the AMF strength near the periphery of the arc is more influential than that at the centre of the electrodes in resisting arc constriction.
Solid-state high voltage, DC power distribution and control
Gaudreau, M P J; Hawkey, T J; Kempkes, M A; Mulvaney, J M; Ver Planck, P
1999-01-01
Future high voltage, high power systems in the early stages of planning include U.S. large accelerator programs such as the Next Linear Collider (NLC), Spallation Neutron Source (SNS), and international systems at DESY, CERN and KEK. There are also many nuclear fusion and multi-megawatt systems proposed for construction or upgrade. Each of these programs faces the challenge of distributing and controlling the high power required by tens to hundreds of RF amplifier tubes (e.g., klystrons) cost effectively. In this paper, we present a new approach for distributing and modulating power based upon recent technological developments in high voltage, high power, solid state switching. DTI's development of fast, high voltage, opening and closing solid state switches enable, for the first time at high voltage, a nearly lossless "DC transformer". With this DC transformer (i.e., down converter or buck regulator), it is now possible to distribute unregulated high voltage DC power in a large facility, and regulate and con...
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.
Camacho Santiago, Antonio; Castilla Fernández, Miguel; Miret Tomàs, Jaume; Guzmán Solà, Ramon; Borrell Sanz, Angel
2014-01-01
Grid faults are one of the most severe problems for network operation. Distributed generation power plants can help to mitigate the adverse effects of these perturbations by injecting reactive power during the sag and the post-fault operation. Thus, the risk of cascade disconnection and voltage collapse can be reduced. The proposed reactive power control is intended to regulate the maximum and minimum phase voltages at the point of common coupling within the limits established in grid codes f...
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. PMID:24213301
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.
Distributed continuous energy scheduling for dynamic virtual power plants
International Nuclear Information System (INIS)
This thesis presents DynaSCOPE as distributed control method for continuous energy scheduling for dynamic virtual power plants (DVPP). DVPPs aggregate the flexibility of distributed energy units to address current energy markets. As an extension of the Virtual Power Plant concept they show high dynamics in aggregation and operation of energy units. Whereas operation schedules are set up for all energy units in a day-ahead planning procedure, incidents may render these schedules infeasible during execution, like deviation from prognoses or outages. Thus, a continuous scheduling process is needed to ensure product fulfillment. With DynaSCOPE, software agents representing single energy units solve this problem in a completely distributed heuristic approach. Using a stepped concept, several damping mechanisms are applied to allow minimum disturbance while continuously trying to fulfill the product as contracted at the market.
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.
Is cortical distribution of spectral power a stable individual characteristic?
Knyazev, Gennady G
2009-05-01
General understanding in EEG research is that cortical distribution of spectral power varies as a function of time, frequency, state, and experimental condition. There are findings, however, which show that individual-specific patterns of cortical spectral power distribution could be amazingly stable, at least in some experimental conditions. In this study two different experimental datasets were used to analyze stability and variability of individual pattern of cortical spectral power distribution across time, experimental conditions, and frequency bands. First experiment consisted of presentation of pictures of emotional facial expressions. Second experiment was an auditory stop-signal task. In both experiments a number of psychometric measures were obtained from each participant. It has been shown that in spite of high short-term variability, individual-specific patterns of cortical spectral power distribution are remarkably stable across frequency bands, long periods of time, and experimental conditions. These patterns are related to state and trait participant's characteristics. The antero-posterior spectral power gradient emerged as the most prominent feature associated with important personality dimensions. Relatively higher oscillatory activity in the frontal cortical region relates to female gender and Behavioral Inhibition tendencies. Relatively higher activity at posterior sites is associated with Extraversion. Significant differences in event-related spectral perturbations upon presentation of emotionally loaded stimuli were found between high and low antero-posterior gradient participants. These data show that cortical distribution of oscillatory activity may be seen as a relatively stable individual characteristic. Enhanced or diminished oscillatory activity of some cortical regions, such as the prefrontal cortex, may play an important role in organization of human behavior. PMID:19047002
Learning geotemporal nonstationary failure and recovery of power distribution.
Wei, Yun; Ji, Chuanyi; Galvan, Floyd; Couvillon, Stephen; Orellana, George; Momoh, James
2014-01-01
Smart energy grid is an emerging area for new applications of machine learning in a nonstationary environment. Such a nonstationary environment emerges when large-scale failures occur at power networks because of external disruptions such as hurricanes and severe storms. Power distribution networks lie at the edge of the grid, and are especially vulnerable to external disruptions. Quantifiable approaches are lacking and needed to learn nonstationary behaviors of large-scale failure and recovery of power distribution. This paper studies such nonstationary behaviors in three aspects. First, a novel formulation is derived for an entire life cycle of large-scale failure and recovery of power distribution. Second, spatial-temporal models of failure and recovery of power distribution are developed as geolocation-based multivariate nonstationary GI(t)/G(t)/∞ queues. Third, the nonstationary spatial-temporal models identify a small number of parameters to be learned. Learning is applied to two real-life examples of large-scale disruptions. One is from Hurricane Ike, where data from an operational network is exact on failures and recoveries. The other is from Hurricane Sandy, where aggregated data is used for inferring failure and recovery processes at one of the impacted areas. Model parameters are learned using real data. Two findings emerge as results of learning: 1) failure rates behave similarly at the two different provider networks for two different hurricanes but differently at the geographical regions and 2) both the rapid and slow-recovery are present for Hurricane Ike but only slow recovery is shown for a regional distribution network from Hurricane Sandy. PMID:24806656
Energy Technology Data Exchange (ETDEWEB)
Smith, R. S.
1998-10-27
Existing thermal hydraulics computer codes can account for variations in power and temperature in the axial and thickness directions but variations across the width of the plate cannot be accounted for. In the case of fuel plates in an annular core this can lead to significant errors which are accentuated by the presence of an oxide layer that builds up on the aluminum cladding with burnup. This paper uses a three dimensional SINDA model to account for the transverse variations in power. The effect of oxide thickness on these differences is studied in detail. Power distribution and fuel conductivity are also considered. The lower temperatures predicted with the SINDA model result in a greater margin to clad and fuel damage.
Energy Technology Data Exchange (ETDEWEB)
Smith, R.S.; Hanan, N.A. [Argonne National Lab., IL (United States)
1998-07-01
Existing thermal hydraulics computer codes can account for variations in power and temperature in the axial and thickness directions but variations across the width of the plate cannot be accounted for. In the case of fuel plates in an annular core this can lead to significant errors which are accentuated by the presence of an oxide layer that builds up on the aluminium cladding with burnup. This paper uses a three dimensional SINDA model to account for the transverse variations in power. The effect of oxide thickness on these differences is studied in detail. Power distribution and fuel conductivity are also considered. The lower temperatures predicted with the SNDA model result in a greater margin to clad and fuel damage. (author)
International Nuclear Information System (INIS)
Existing thermal hydraulics computer codes can account for variations in power and temperature in the axial and thickness directions but variations across the width of the plate cannot be accounted for. In the case of fuel plates in an annular core this can lead to significant errors which are accentuated by the presence of an oxide layer that builds up on the aluminium cladding with burnup. This paper uses a three dimensional SINDA model to account for the transverse variations in power. The effect of oxide thickness on these differences is studied in detail. Power distribution and fuel conductivity are also considered. The lower temperatures predicted with the SNDA model result in a greater margin to clad and fuel damage. (author)
PWR power distribution flattening using Quantum Particle Swarm intelligence
International Nuclear Information System (INIS)
Highlights: ► Quantum Particle Swarm Optimization (QPSO) is applied to ICFMO. ► A differential mutation operator is added to enhance QPSO performance (QPSO-DM). ► PSO, QPSO and QPSO-DM are tested on Bushehr Nuclear Power Plant (BNPP). ► It is observed that QPSO-DM is comparable to PSO and QPSO on ICFMO. - Abstract: In-core fuel management optimization (ICFMO) is one of the most challenging concepts of nuclear engineering. Most of the strategies implemented for optimizing fuel loading pattern in nuclear power reactors are based on maximizing core multiplication factor in order to extract maximum energy and reducing power peaking factor from a predetermined value to maintain fuel integrity. In this investigation a new method using Quantum Particle Swarm Optimization (QPSO) algorithm has been developed in order to flatten power density distribution in WWER-1000 Bushehr Nuclear Power Plant (BNPP) and thereby provide a better safety margin. The result and convergence of this method show that QPSO performs very well and is comparable to PSO. Furthermore, an operator has been added to QPSO as a mutation operator. This algorithm, called QPSO-DM, shows a better performance on ICFMO than PSO and QPSO. MATLAB software was used to map PSO, QPSO and QPSO-DM for loading pattern optimization. Multi-group constants generated by WIMS for different fuel configurations were fed into CITATION to obtain the power density distribution
Chakraborty, Soumya; Saulnier, Gary J; Wilt, Kyle W; Curt, Edward; Scarton, Henry A; Litman, Robert B
2015-10-01
Acoustic-electric channels have been used in the recent past to send power and data through thin metallic barriers. Acoustic-electric channels formed along a structure which are highly attenuative and nonreverberant could have potential applications in aerospace, nuclear, and oil industries, among others. This work considers data transmission along the length of a cylindrical pipe both when in air and when filled and immersed in water using shear waves of transverse polarity. To combat the effects of frequency selectivity and to address the available power constraints, a simple modulation scheme using noncoherent demodulation is employed for data transmission: chirp-on-off keying (Chirp-OOK). The wideband nature of the chirp waveform provides resilience against nulls in the channel response while making it possible to implement a simple noncoherent energy detector. Monte Carlo simulation results using measured channel responses suggest that the bit error rate performance of the scheme matches quite closely with the theoretical results. The energy detector performance is independent of the type of the channel used as long as intersymbol-interference is negligible and same received Eb/N0 is maintained. A low-power prototype hardware system was implemented using microcontrollers, commercial ICs, and custom circuits. Successful data transmission was achieved across the 4.8 m length of pipe (in air and water) for a data rate of 100 bps using approximately 5 mW of transmit power. PMID:26470041
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.
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.
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.
Transverse Vibration of Axially Moving Functionally Graded Materials Based on Timoshenko Beam Theory
Directory of Open Access Journals (Sweden)
Suihan Sui
2015-01-01
Full Text Available The transverse free vibration of an axially moving beam made of functionally graded materials (FGM is investigated using a Timoshenko beam theory. Natural frequencies, vibration modes, and critical speeds of such axially moving systems are determined and discussed in detail. The material properties are assumed to vary continuously through the thickness of the beam according to a power law distribution. Hamilton’s principle is employed to derive the governing equation and a complex mode approach is utilized to obtain the transverse dynamical behaviors including the vibration modes and natural frequencies. Effects of the axially moving speed and the power-law exponent on the dynamic responses are examined. Some numerical examples are presented to reveal the differences of natural frequencies for Timoshenko beam model and Euler beam model. Moreover, the critical speed is determined numerically to indicate its variation with respect to the power-law exponent, axial initial stress, and length to thickness ratio.
Power distribution unfolding on the basis of in-core rhodium powered detector readings
International Nuclear Information System (INIS)
The task of unfolding of core power distribution for WWER reactors consists of processing of Self Powered Neutron Detector measurements to obtain estimated values for the uninstrumented assemblies. The method described in the report relies on 3-D power distributions calculated with BIPR-5 code and adjusted to instrumented assemblies to reproduce SPND measurements. The multiplicative modifying function is used for this purpose. Earlier a simple method was proposed and evaluated, in which measured power densities served as internal boundary conditions in the BIPR-5 calculations of the 3-D distributions for the entire core. Both methods have been tested using data from Loviisa-1 reactor core, consisting of 349 hexagonal fuel assemblies, each 14.7 cm across and 250 cm in length (active length). The SPNDs were placed on 4 levels: 50, 100, 150, 200 cm above the bottom of reactor core in 36 instrumented assemblies. Refs, figs and tabs
Energy Technology Data Exchange (ETDEWEB)
Qin, SB; Cady, ST; Dominguez-Garcia, AD; Pilawa-Podgurski, RCN
2015-04-01
This paper presents the theory and implementation of a distributed algorithm for controlling differential power processing converters in photovoltaic (PV) applications. This distributed algorithm achieves true maximum power point tracking of series-connected PV submodules by relying only on local voltage measurements and neighbor-to-neighbor communication between the differential power converters. Compared to previous solutions, the proposed algorithm achieves reduced number of perturbations at each step and potentially faster tracking without adding extra hardware; all these features make this algorithm well-suited for long submodule strings. The formulation of the algorithm, discussion of its properties, as well as three case studies are presented. The performance of the distributed tracking algorithm has been verified via experiments, which yielded quantifiable improvements over other techniques that have been implemented in practice. Both simulations and hardware experiments have confirmed the effectiveness of the proposed distributed algorithm.
Electrical power distribution system operating experience review for fusion applications
International Nuclear Information System (INIS)
This paper describes safety research on electrical distribution systems applicable to fusion facilities. Electrical power has many uses in both magnetic and inertial fusion experiments; it is the most important support system for any fusion experiment. Electricity powers a wide variety of plant equipment, including vacuum pumps, magnets, coolant pumps, air handlers, compressors, and either plasma heating or target implosion drivers. Electricity also powers instrumentation and controls, control and data acquisition computers, accident mitigation systems and site security systems. Most facilities use electrical power to ensure adequate confinement of radioactive materials via air pressure zone control, valve isolation, and operation of cleanup systems. As a result, operating experiences of electrical switchgear, cabling, motor control centers, and electrical panels have been examined for reliability, maintenance times, accident case histories, accident initiating event frequencies, and personnel safety issues. Electrical component failure rates and repair times, and initiating event frequencies are presented in this paper
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...... is important for stabilizing the overall network and the active damper should be placed near to the problematic power devices. Finally, the unstable network with five inverters is able to obtain stability by adopting an active damper to the place where its ability becomes the most effective....
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
International Nuclear Information System (INIS)
The influence of spatial power generation shape on thermal-hydraulics behaviour of the fuel rod bundle has been investigated. Particularly, the occurrence of the local Boiling Transition has been analysed, indicating that conditions for the Critical Heat Flux (CHF) are reached somewhere within the boiling water channels in the assembly. The two-phase coolant flow within the bundle is represented with the two-fluid model in 3D space. The porous medium concept is applied in the simulation of the two-phase flow through the rod bundle implying nonequilibrium thermal and flow conditions. The governing equations in three-dimensions are discretized with the control volume method. The 3D numerical simulation and analyses of thermal-hydraulics in a complex geometry of an advanced nuclear fuel assembly are performed for conditions of a partial and/or complete rods uncovering indicating occurrence of high quality CHF - Dryout. The obtained results from numerical simulations are compared with experimental Critical Power data obtained from full scale tests. Employed is an electrically heated test rod bundle with real 1:1 geometry. Different radial and axial power distributions are used with wide range of inlet mass flow rates (2 - 19 kg/s) and coolant inlet subcooling (25 - 185 kJ/kg). The coolant pressure, equal to 6.9 MPa, is typical for BWRs conditions. Comparison of the predicted Critical Power values with measured data shows encouraging agreements for all analysed power distributions and the results completely reflect measured two-phase mixture cross flows, steam void distribution and spatial positions of Dryout onsets. Based on performed numerical investigation, an improvement of Dryout criteria is proposed. Dynamic effects of power shape change on spatial thermal hydraulics and hence on CHF occurrence as well as the influence of transfer function on thermal hydraulics under cyclic power and/or flow rate changes are also being analysed. Experiments for such verifications
Energy Technology Data Exchange (ETDEWEB)
Stosic, Zoran V. [Framatome ANP GmbH . NBTT, Erlangen (Germany)], e-mail: Zoran.Stosic@Framatome-ANP.de; Stevanovic, Vladimir D. [Framatome ANP GmbH, Erlangen (Germany); Iguchi, Tadashi [Japan Atomic Energy Research Institute (JAERI), Ibaraki (Japan)
2001-07-01
The influence of spatial power generation shape on thermal-hydraulics behaviour of the fuel rod bundle has been investigated. Particularly, the occurrence of the local Boiling Transition has been analysed, indicating that conditions for the Critical Heat Flux (CHF) are reached somewhere within the boiling water channels in the assembly. The two-phase coolant flow within the bundle is represented with the two-fluid model in 3D space. The porous medium concept is applied in the simulation of the two-phase flow through the rod bundle implying nonequilibrium thermal and flow conditions. The governing equations in three-dimensions are discretized with the control volume method. The 3D numerical simulation and analyses of thermal-hydraulics in a complex geometry of an advanced nuclear fuel assembly are performed for conditions of a partial and/or complete rods uncovering indicating occurrence of high quality CHF - Dryout. The obtained results from numerical simulations are compared with experimental Critical Power data obtained from full scale tests. Employed is an electrically heated test rod bundle with real 1:1 geometry. Different radial and axial power distributions are used with wide range of inlet mass flow rates (2 - 19 kg/s) and coolant inlet subcooling (25 - 185 kJ/kg). The coolant pressure, equal to 6.9 MPa, is typical for BWRs conditions. Comparison of the predicted Critical Power values with measured data shows encouraging agreements for all analysed power distributions and the results completely reflect measured two-phase mixture cross flows, steam void distribution and spatial positions of Dryout onsets. Based on performed numerical investigation, an improvement of Dryout criteria is proposed. Dynamic effects of power shape change on spatial thermal hydraulics and hence on CHF occurrence as well as the influence of transfer function on thermal hydraulics under cyclic power and/or flow rate changes are also being analysed. Experiments for such verifications
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 $\\...
Health assessment of electric power distribution system in NPP
International Nuclear Information System (INIS)
Uninterrupted electrical power is required to continue the decay heat removal and containment of radioactive leakage, subsequent to reactor shut-down following an accident. Assessment of the integrity of electrical power supply system, after an accident, and restoration of supply, at least to the electrical networks feeding the critical loads, is therefore of utmost importance. The availability of one or more of the emergency power sources - DGs, batteries, offsite power etc. - and the survival of the electrical distribution network up to the critical loads are the necessary conditions for recovery. External sources may be required to be connected in-situ, if none of the emergency sources are available. Few cables may have to be laid if the distribution network is not recoverable. To carry out these activities in a post-accident scenario, it is highly desirable to have an in-situ diagnostic system that can assess and present the health of the electrical distribution network to the plant personnel. This paper discusses about a diagnostic technique capable of monitoring and detecting hard (e.g., Open circuit) as well as soft faults created due to rapid degradation of the cables caused due to fire/heat or other mechanisms. (author)
Energy Technology Data Exchange (ETDEWEB)
NONE
2000-02-29
The open distributed automatic power distribution systems were delivered to Naha and Gushikawa branches of Okinawa Electric Power Co. This system adopts such latest technologies as object-oriented design. Its features are as follows: (1) Possible parallel operation by every branch and business office by switching an operation priority between the branch and business office in the case of multi- accidents, (2) Possible free console operation for any businesses regardless of the other console conditions, (3) Automatic decision of power supply by mobile power vehicle for precise power interruption control, (4) Immediate display of the work planning system including data maintenance and operation procedures until the prearranged working date, and (5) Possible manned backup operation at system down of the server. (translated by NEDO)
Modeling the economics and market adoption of distributed power generation
International Nuclear Information System (INIS)
After decades of power generating units increasing in size, there is currently a growing focus on distributed generation, power generation close to energy loads. Investments in large-scale units have been driven by economy of scale, but recent technological improvements on small generating plants have made it possible to exploit the benefits of local power generation to a larger extent than previously. Distributed generation can improve power system efficiency because heat can be recovered from thermal units to supply heat and thermally activated cooling, and because small-scale renewables have a promising end-user market. Further benefits of distributed generation include improved reliability, deferral of often controversial and costly grid investments and reduction of grid losses. The new appeal of small-scale power generation means that there is a need for new tools to analyze distributed generation, both from a system perspective and from the perspective of potential developers. In this thesis, the focus is on the value of power generation for end-users. The thesis identifies how an end-user can find optimal distributed generation systems and investment strategies under a variety of economic and regulatory scenarios. The final part of the thesis extends the analysis with a bottom up model of how the economics of distributed generation for a representative set of building types can transfer to technology diffusion in a market. Four separate research papers make up the thesis. In the first paper, Optimal Investment Strategies in Decentralized Renewable Power Generation under Uncertainty, a method for evaluation of investments in renewable power units under price uncertainty is presented. It is assumed the developer has a building with an electricity load and a renewable power resource. The case study compares a set of wind power systems with different capacity and finds that capacity depends on the electricity price and that there under uncertain prices can be a
Spatial and spectral oxide trap distributions of power MOSFETs
International Nuclear Information System (INIS)
Commercial power MOSFET (A, B and C) oxides have been characterized by irradiation and isochronal annealing. Low dose irradiation (100 krad(SiO2) under positive and negative bias shows a uniform oxide charge trapping for the two unhardened devices and an interfacial oxide trap distribution in the case of the rad-hard device. High dose irradiation (10 Mrad(SiO2) under high negative bias demonstrates the build-up of an electron trapped charge for device A and the conduction at high dose of a parasitic transistor for device B. Irradiation up to 100 krad(SiO2) and isochronal annealing under positive bias is carried out to compare the spectral distribution of oxide traps between device A oxide and reference buried oxides (SIMOX and UNIBOND). Despite a similar trapping behavior, their spectral distributions are different. Device A presents a lower energy distribution than buried oxides. (authors)
International Nuclear Information System (INIS)
Purpose: To evaluate quantitatively dose distributions from helical, axial and cone-beam CT clinical imaging techniques by measurement using a two-dimensional (2D) diode-array detector. Methods: 2D-dose distributions from selected clinical protocols used for axial, helical and cone-beam CT imaging were measured using a diode-array detector (MapCheck2). The MapCheck2 is composed from solid state diode detectors that are arranged in horizontal and vertical lines with a spacing of 10 mm. A GE-Light-Speed CT-simulator was used to acquire axial and helical CT images and a kV on-board-imager integrated with a Varian TrueBeam-STx machine was used to acquire cone-beam CT (CBCT) images. Results: The dose distributions from axial, helical and cone-beam CT were non-uniform over the region-of-interest with strong spatial and angular dependence. In axial CT, a large dose gradient was measured that decreased from lateral sides to the middle of the phantom due to large superficial dose at the side of the phantom in comparison with larger beam attenuation at the center. The dose decreased at the superior and inferior regions in comparison to the center of the phantom in axial CT. An asymmetry was found between the right-left or superior-inferior sides of the phantom which possibly to angular dependence in the dose distributions. The dose level and distribution varied from one imaging technique into another. For the pelvis technique, axial CT deposited a mean dose of 3.67 cGy, helical CT deposited a mean dose of 1.59 cGy, and CBCT deposited a mean dose of 1.62 cGy. Conclusions: MapCheck2 provides a robust tool to measure directly 2D-dose distributions for CT imaging with high spatial resolution detectors in comparison with ionization chamber that provides a single point measurement or an average dose to the phantom. The dose distributions measured with MapCheck2 consider medium heterogeneity and can represent specific patient dose
Energy Technology Data Exchange (ETDEWEB)
Chacko, M; Aldoohan, S; Sonnad, J; Ahmad, S; Ali, I [University of Oklahoma Health Science Center, Oklahoma City, OK (United States)
2015-06-15
Purpose: To evaluate quantitatively dose distributions from helical, axial and cone-beam CT clinical imaging techniques by measurement using a two-dimensional (2D) diode-array detector. Methods: 2D-dose distributions from selected clinical protocols used for axial, helical and cone-beam CT imaging were measured using a diode-array detector (MapCheck2). The MapCheck2 is composed from solid state diode detectors that are arranged in horizontal and vertical lines with a spacing of 10 mm. A GE-Light-Speed CT-simulator was used to acquire axial and helical CT images and a kV on-board-imager integrated with a Varian TrueBeam-STx machine was used to acquire cone-beam CT (CBCT) images. Results: The dose distributions from axial, helical and cone-beam CT were non-uniform over the region-of-interest with strong spatial and angular dependence. In axial CT, a large dose gradient was measured that decreased from lateral sides to the middle of the phantom due to large superficial dose at the side of the phantom in comparison with larger beam attenuation at the center. The dose decreased at the superior and inferior regions in comparison to the center of the phantom in axial CT. An asymmetry was found between the right-left or superior-inferior sides of the phantom which possibly to angular dependence in the dose distributions. The dose level and distribution varied from one imaging technique into another. For the pelvis technique, axial CT deposited a mean dose of 3.67 cGy, helical CT deposited a mean dose of 1.59 cGy, and CBCT deposited a mean dose of 1.62 cGy. Conclusions: MapCheck2 provides a robust tool to measure directly 2D-dose distributions for CT imaging with high spatial resolution detectors in comparison with ionization chamber that provides a single point measurement or an average dose to the phantom. The dose distributions measured with MapCheck2 consider medium heterogeneity and can represent specific patient dose.
Agent Based Control of Electric Power Systems with Distributed Generation
DEFF Research Database (Denmark)
Saleem, Arshad
Distributed generation, decentralized and local control, self organization and autonomy are evident trends of today's electric power systems focusing on innovative control architectures such as MicroGrids, Virtual Power Plants, Cell based systems, plug-in electric vehicles and real time markets...... subsystems that are able to coordinate, communicate, cooperate, adapt to emerging situations and self organize in an intelligent way. At the same time, rapid development in information and and communication technologies (ICT) have brought new opportunities and elucidations. New Technologies and standards...
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.
PHEMT Distributed Power Amplifier Adopting Broadband Impedance Transformer
DEFF Research Database (Denmark)
Narendra, K.; Limiti, E.; Paoloni, C.; Zhurbenko, Vitaliy
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...... transmission line. The output power of approximately 600 mW, with an associated gain of 9 dB and PAE greater than 30 percent, is demonstrated in the frequency range from 10 to 1800 MHz....
Improvement of the axial diffusion solver of DeCART employing 1-D transport solution
International Nuclear Information System (INIS)
Instead of the 3-D transport equation, DeCART solves a transverse leakage coupled radial transport and axial diffusion equations to obtain an approximate 3-D transport solution. In this paper, two of the approximations contained in DeCART related with diffusion constants and cell homogenization are exmained, and practical improvement schemes are suggested. To overcome the diffusion approximation used in the axial direction, a current conservation scheme based on the axial 1-D transport solution is introduced. To overcome the cell homogenization effect, a plane height refinement scheme is employed near the axial core/reflector boundary where homogenization constants vary significantly in the axial direction within the plane. These schemes are evaluated by solving the 3-D VENUS-2 MOX core benchmark. The current conservation and plane height refinement schemes bring about 280 pcm and 100 pcm improvement in k-eff, respectively, and about 390 pcm in total, but trivial effects in the power distribution
Modeling Uncertainties in Power System by Generalized Lambda Distribution
Xiao, Qing
2014-06-01
This paper employs the generalized lambda distribution (GLD) to model random variables with various probability distributions in power system. In the context of the probability weighted moment (PWM), an optimization-free method is developed to assess the parameters of GLD. By equating the first four PWMs of GLD with those of the target random variable, a polynomial equation with one unknown is derived to solve for the parameters of GLD. When employing GLD to model correlated multivariate random variables, a method of accommodating the dependency is put forward. Finally, three examples are worked to demonstrate the proposed method.
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.
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
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.
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 system...... 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 is...... applied in this analysis. A typical Danish primary power distribution system is used as a test case for the studies. From the simulation results, not more than 10% of electric vehicles could be integrated in the test system for the dump charging mode. About 40% of electric vehicle loads could be...
Strategies for Power/Energy Saving in Distribution Networks
Directory of Open Access Journals (Sweden)
GRIGORAS, G.
2010-05-01
Full Text Available The power/energy losses reduction in distribution systems is an important issue during planning and operation, with important technical and economical implications. Thus, the energy losses minimization implies not only the technical improvement of the network, through its renewal with the introduction of the technological innovations in the equipment and circuit components as well as the optimal planning of the design and development of the network, but also requires the use of the methods and software tools to facilitate the operation process. The paper presents a strategy for power/energy saving which replacement of the 6 kV voltage level with 20 kV voltage level in correlation with the extent of using efficient transformers. In this line, different urban distribution networks were analyzed using fuzzy techniques.
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 as well as their major characteristics is given. New solutions to optimize the synchronization methods when running on distorted grid conditions are discussed. Simulation and experimental results are used to evaluate the behavior of the synchronization methods under different kind of grid...
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 ...
Planning Models for Single Wire Earth Return Power Distribution Networks
Bakkabulindi, Geofrey
2012-01-01
The high cost of grid extension to rural areas, often characterized by scattered communities with low load densities, requires the use of low cost electrification technologies to ensure economic viability. In Single Wire Earth Return (SWER) power distribution networks, the earth itself forms the current return path of the single phase system leading to significant cost savings on conductors, poles and poletop hardware compared to conventional systems. However, challenges exist in SWER with re...
Optimization of reliability electric power transmission and distribution networks
Dorin Sarchiz; Daniel Bucur
2011-01-01
The problem of quality services provided by suppliers of electricity is currently a major problem due to significant economic implications given the complexity and cost of electric power transmission and distribution systems on the one hand and consumers on the other side who are becoming more demanding in regarding the quality of electricity supplied.Starting from this real situation, the paper develops nonlinear mathematical model of optimization of reliability through redundancy, knowing t...
Distributed Frequency Control in Power Grids Under Limited Communication
Parandehgheibi, Marzieh; Turitsyn, Konstantin; Modiano, Eytan
2016-01-01
In this paper, we analyze the impact of communication failures on the performance of optimal distributed frequency control. We consider a consensus-based control scheme, and show that it does not converge to the optimal solution when the communication network is disconnected. We propose a new control scheme that uses the dynamics of power grid to replicate the information not received from the communication network, and prove that it achieves the optimal solution under any single communicatio...
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...
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.
Power distribution monitoring and control in the RBMK type reactors
International Nuclear Information System (INIS)
Considered are the structures of monitoring and control systems for the RBMK-1000 reactor including three main systems with high independence: the control and safety system (CSS); the system for physical control of energy distribution (SPCED) as well as the Scala system for centralized control (SCC). Main functions and peculiarities of each system are discussed. Main attention is paid to new structural solutions and new equipment components used in these systems. Described are the RBMK operation software and routine of energy distribution control in it. It is noted that the set of reactor control and monitoring systems has a hierarchical structure, the first level of which includes analog systems (CSS and SPCED) normalizing and transmitting detector signals to the systems of the second level based on computers and realizing computer data processing, data representation to the operator, automatic (through CSS) control for energy distribution, diagnostics of equipment condition and local safety with provision for existing reserves with respect to crisis and thermal loading of fuel assemblies. The third level includes a power computer carrying out complex physical and optimization calculations and providing interconnections with the external computer of power system. A typical feature of the complex is the provision of local automatic safety of the reactor from erroneous withdrawal of any control rod. The complex is designed for complete automatization of energy distribution control in reactor in steady and transient operation conditions
The place of solar power: an economic analysis of concentrated and distributed solar power
Banoni Vanessa; Arnone Aldo; Fondeur Maria; Hodge Annabel; Offner J; Phillips Jordan K
2012-01-01
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 constr...
On-line generation of core monitoring power distribution in the SCOMS couppled with core design code
International Nuclear Information System (INIS)
The paper provides the description of the methodology and main program module of power distribution calculation of SCOMS(SMART COre Monitoring System). The simulation results of the SMART core using the developed SCOMS are included. The planar radial peaking factor(Fxy) is relatively high in SMART core because control banks are inserted to the core at normal operation. If the conventional core monitoring method is adapted to SMART, highly skewed planar radial peaking factor Fxy yields an excessive conservatism and reduces the operation margin. In addition to this, the error of the core monitoring would be enlarged and thus operating margin would be degraded, because it is impossible to precalculate the core monitoring constants for all the control banks configurations taking into account the operation history in the design stage. To get rid of these drawbacks in the conventional power distribution calculation methodology, new methodology to calculate the three dimensional power distribution is developed. Core monitoring constants are calculated with the core design code (MASTER) which is on-line coupled with SCOMS. Three dimensional (3D) power distribution and the several peaking factors are calculated using the in-core detector signals and core monitoring constant provided at real time. Developed methodology is applied to the SMART core and the various core states are simulated. Based on the simulation results, it is founded that the three dimensional peaking factor to calculate the Linear Power Density and the pseudo hot-pin axial power distribution to calculate the Departure Nucleate Boiling Ratio show the more conservative values than those of the best-estimated core design code, and SCOMS adapted developed methodology can secures the more operation margin than the conventional methodology
Flattening of UCFR Power Distribution with Fuel Zoning
Energy Technology Data Exchange (ETDEWEB)
Tak, Tae Woo; Lee, Deok Jung [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)
2014-10-15
The Ultra-long Cycle Fast Reactor (UCFR) utilizes a breed-and-burn strategy to achieve such a long cycle by using low enrichment uranium (LEU) as an igniter and natural uranium (NU) as a blanket material. Only the feasibility of the core from the neutronics point of view had been reported, so the optimization of UCFR was performed to consider thermal hydraulic feedback analysis and mitigate the power peaking issue. Also the study on using spent fuel for the blanket material has been performed. It was noticed that the high reactor power rating combined with high peaking could cause a very large amount of local power and consequently violate the limits of temperature or fast neutron fluence in the fuel and clad regions. Thorium fuel had been utilized as a blanket material to flatten the radial power distribution of UCFR-1000 and the result shows the radial peaking factor at the center decreases at the middle of cycle (MOC), which confirmed that thorium loading has an effect on the power flattening. In this paper, several designs of UCFR-1000 have been developed to flatten the power distribution not only at MOC but also throughout the whole cycle. They have an inner fuel region whose radius is 35% of the whole fuel region in contrast to the previous UCFR-1000 with an inner fuel region of only 1/4 the radius of the whole fuel region. It has been confirmed that fuel zoning can achieve radial power flattening, which decreases the maximum power peak. The Case 1 core has a center peak at BOC like the reference core, but the peaking factor has decreased due to the thorium fuel in the inner fuel region, which is shown by the fact that at year 20 it has decreased from 1.57 to 1.14. In contrast to the reference and Case 1 cores, the peak of the Case 2 and Case 3-1 cores appears in the peripheral region at BOC, which causes a power shape more flattened at MOC and EOC than that of Case 1. At EOC, Case 3-1 has a maximum peak of 1.15 while the reference case has a maximum peak of
Rongxiang Yuan; Timing Li; Xiangtian Deng; Jun Ye
2016-01-01
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...
Anisotropic Azimuthal Power and Temperature distribution on FuelRod. Impact on Hydride Distribution
Energy Technology Data Exchange (ETDEWEB)
Motta, Arthur [Pennsylvania State Univ., State College, PA (United States); Ivanov, Kostadin [Pennsylvania State Univ., State College, PA (United States); Arramova, Maria [Pennsylvania State Univ., State College, PA (United States); Hales, Jason [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2015-04-29
The degradation of the zirconium cladding may limit nuclear fuel performance. In the high temperature environment of a reactor, the zirconium in the cladding corrodes, releasing hydrogen in the process. Some of this hydrogen is absorbed by the cladding in a highly inhomogeneous manner. The distribution of the absorbed hydrogen is extremely sensitive to temperature and stress concentration gradients. The absorbed hydrogen tends to concentrate near lower temperatures. This hydrogen absorption and hydride formation can cause cladding failure. This project set out to improve the hydrogen distribution prediction capabilities of the BISON fuel performance code. The project was split into two primary sections, first was the use of a high fidelity multi-physics coupling to accurately predict temperature gradients as a function of r, θ , and z, and the second was to use experimental data to create an analytical hydrogen precipitation model. The Penn State version of thermal hydraulics code COBRA-TF (CTF) was successfully coupled to the DeCART neutronics code. This coupled system was verified by testing and validated by comparison to FRAPCON data. The hydrogen diffusion and precipitation experiments successfully calculated the heat of transport and precipitation rate constant values to be used within the hydrogen model in BISON. These values can only be determined experimentally. These values were successfully implemented in precipitation, diffusion and dissolution kernels that were implemented in the BISON code. The coupled output was fed into BISON models and the hydrogen and hydride distributions behaved as expected. Simulations were conducted in the radial, axial and azimuthal directions to showcase the full capabilities of the hydrogen model.
'MIDICORE' WWER-1000 core periphery power distribution benchmark proposal
International Nuclear Information System (INIS)
The MIDICORE benchmark is a 2D calculation benchmark based on the WWER-1000 reactor core cold state geometry with taking into the account the geometry of explicit radial reflector. The main task of this benchmark is to test the pin by pin power distribution in selected fuel assemblies that are placed mainly at the border of the WWER-1000 core. This is due to an observed phenomenon at calculation of the 'first core loading' (completely composed from TVEL TVSA-T fresh fuel assemblies) at Temelin NPP (WWER-1000 core), where the maximum of fuel pin power was found in a peripheral fuel assemblies in a fuel pin at assembly edge in direction to the core centre. This phenomenon consist not only in position where this maximum occurs, but especially in relatively big difference of fuel pin power value observed when this value was determined by codes based on pin to pin diffusion difference method on one side and by codes based on nodal diffusion method with pin power reconstruction on the other side. Because value of fuel pin power is not directly measured by the core monitoring system, a decision about a proposal of benchmark of this kind has been made. In this contribution we define the MIDICORE benchmark; we present the preliminary reference Monte Carlo calculation results and also preliminary MOBY-DICK macro code calculation results. (Authors)
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.
Electric power transmission and distribution in Germany - an NTPA success
International Nuclear Information System (INIS)
The German Energy Law of April 1998 opened 100 percent of the German electricity market to competition without any transition phase. Over four years later, the degree of market opening is still ahead of that in many other European countries. Transition phases elsewhere have been dominated by the need to develop detailed rules not only for the functioning of the power markets - e.g. in power exchanges - but also for the transmission and distribution system operators and for the data exchange between market participants. Especially the data exchange needs for the handling of household customers switching suppliers has been a challenge in all the countries that have opened the household customer market. But also the network access fees on both transmission and distribution level are still being debated in many countries. The German governments have so far chosen to let the network operators develop the access rules, pricing rules and data exchange standards in intense - and intensely observed - negotiations with the network users. Important outcomes of such negotiations include the well-known Associations' Agreements, GridCode, DistributionCode, MeteringCode as well as the government's Best Practice Recommendations on data exchange standards for the switching between suppliers. One important advantage of this negotiation-based rather than regulatory approach is its speed and flexibility. For example, the Associations' Agreement on network access fees is now valid in its third version, and each successive version included important learning from the experience of both network operators and network users with the previous agreement. This paper will summarise the legal framework of the liberalised power market in Germany and focus on the current state of pricing rules in the Associations' Agreement, of well advanced comparisons run by VDN, of the network access fees of hundreds of distribution system operators including specific data on structural differences of their
Eriksson, Stefanie; Lasič, Samo; Nilsson, Markus; Westin, Carl-Fredrik; Topgaard, Daniel
2015-01-01
We introduce a nuclear magnetic resonance method for quantifying the shape of axially symmetric microscopic diffusion tensors in terms of a new diffusion anisotropy metric, DΔ, which has unique values for oblate, spherical, and prolate tensor shapes. The pulse sequence includes a series of equal-amplitude magnetic field gradient pulse pairs, the directions of which are tailored to give an axially symmetric diffusion-encoding tensor b with variable anisotropy bΔ. Averaging of data acquired for...
Axial velocity in decaying swirl flow
Algifri, A. H.; Bhardwaj, R. K.; Rao, Y. V. N.
1988-09-01
Experiments were carried out on turbulent swirling flow with variable initial swirl at different flow rates to study the effect of swirl on axial velocity. A correlation was made between the defect in the swirling flow axial velocity and the swirl number which locally defines the swirl intensity. An expression which can be used to predict the axial velocity distribution of turbulent swirling flow in a pipe is presented.
Full power operation after long time with low power operation
International Nuclear Information System (INIS)
It is simulated Angra-1 nuclear power plant which is operating slight power during long period followed by full power operation. It was calculated the axial power distribution utilizing the 1D model of CITATION code modified by FURNAS. (M.C.K.)
Kwak, Kiho; Kwak, Dongmin; Yoon, Joohong
2015-08-01
A design of an Instantaneous High Power Supply System (IHPSS) with a power distribution management (PDM) for portable military devices is newly addressed. The system includes a power board and a hybrid battery that can not only supply instantaneous high power but also maintain stable operation at critical low temperature (-30 °C). The power leakage and battery overcharge are effectively prevented by the optimal PDM. The performance of the proposed system under the required pulse loads and the operating conditions of a Korean Advanced Combat Rifle employed in the battlefield is modeled with simulations and verified experimentally. The system with the IHPSS charged the fuse setter with 1.7 times higher voltage (8.6 V) than the one without (5.4 V) under the pulse discharging rate (1 A at 0.5 duty, 1 ms) for 500 ms.
Power Distribution Analysis for the ORNL High Flux Isotope Reactor Critical Experiment 3
International Nuclear Information System (INIS)
. Power distributions were obtained for clean core (no poison in moderator and symmetrical rod position at 44.536 cm withdrawn with respect to the core axial midplane) and fully poisoned moderator (1.35 grams of boron per liter in moderator and rods fully withdrawn) conditions. The observed deviations between the experimental and calculated values for both conditions were within the reported experimental uncertainties except for some foils located on the top and bottom edges of the fuel plates.
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.
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. [Georgia Institute of Technology, Atlanta, GA; Smith, Jeff [Electric Power Research Institute, Knoxville, TN; Dugan, Roger [Electric Power Research Institute, Knoxville, TN
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
Research for a New Optimization Model of Electric Distribution Network with Wind Power
Hong Zhang; Xueliang Huang; Jun Li
2013-01-01
In the distribution network with wind power, due to the different costs of different power tariff from different power source, the minimum power loss of the distribution networks does not always correspond to the largest economic efficiency. In the most cases, to ensure the distribution network power quality at the same time get the most economic efficiency is an important goal of the enterprise. The new improved distribution network optimization model is a...
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...
Axial Vircator for Electronic Warfare Applications
L. Drazan; R. Vrana
2009-01-01
This paper deals with a high power microwave generator with virtual cathode – vircator in axial release for electronic warfare applications. The classification of directed energy weapons microwave (DEWM) is introduced together with basic block diagrams of a particular class of DEWM. In the paper, methods for designing vircator pulsed power supply, axial vircator structure, measurement methods and experimental results are presented. The vircator in electromagnetic ammunition is powered b...
Integration of Small Solar Tower Systems Into Distributed Power Islands
International Nuclear Information System (INIS)
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-parks, 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 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 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 heliostats 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
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.
Distributed generation: remote power systems with advanced storage technologies
International Nuclear Information System (INIS)
The paper discusses derived from an earlier hypothetical study of remote villiages. It considers the policy implications for communities who have their own local power resources rather than those distributed through transmission from distant sources such as dams, coal power plants or even renewables generation from wind farms, solar thermal or other resources. The issues today, post 911 and the energy crises in California, Northeast North America and Europe, signal the need for a new and different approach to energy supply(s), reliability and dissemination. Distributed generation (DG) as explored in the earlier paper appears to be one such approach that allows for local communities to become energy self-sufficient. Along with energy conservation, efficiency, and on-site generation, local power sources provide concrete definitions and understandings for heretofore ill defined concepts such as sustainability and eco-systems. The end result for any region and nation-state are 'agile energy systems' which use flexible DG, on-site generation and conservation systems meeting the needs of local communities. Now the challenge is to demonstrate and provide economic and policy structures for implementing new advanced technologies for local communities. For institutionalizing economically viable and sound environmental technologies then new finance mechanisms must be established that better reflect the true costs of clean energy distributed in local communities. For example, the aggregation of procurement contracts for on-site solar systems is far more cost effective than for each business owner, public building or household to purchase its own separate units. Thus mass purchasing contracts that are link technologies as hybrids can dramatically reduce costs. In short public-private partnerships can implement the once costly clean energy technologies into local DG systems
Economic impacts of power electronics on electricity distribution systems
International Nuclear Information System (INIS)
To achieve more efficient energy use, power electronics (PEs) may be employed. However, these introduce nonlinear loads (NLLs) into the system by generating undesired frequencies that are harmonic in relation to (multiples of) the fundamental frequency (60 Hz in Brazil). Consequently, devices using PEs are more efficient but also contribute significantly to degradation of power quality. Besides this, both the conventional rules on design and operation of power systems and the usual premises followed in energy efficiency programs (without mentioning the electricity consumed by the devices themselves) consider the sinusoidal voltage and current waveforms at the fixed fundamental frequency of the power grid. Thus, analysis of electricity consumption reductions in energy efficiency programs that include the use of PEs considers the reduction of kWh to the final consumer but not the additional losses caused by the increase in harmonic distortion. This article contributes to a better understanding of this problem by reporting the results of a case study of the ownership and use of television sets (TV sets) to estimate the economic impacts of residential PEs on a mainly residential electricity distribution system. (author)
Economic impacts of power electronics on electricity distribution systems
International Nuclear Information System (INIS)
To achieve more efficient energy use, power electronics (PEs) may be employed. However, these introduce nonlinear loads (NLLs) into the system by generating undesired frequencies that are harmonic in relation to (multiples of) the fundamental frequency (60 Hz in Brazil). Consequently, devices using PEs are more efficient but also contribute significantly to degradation of power quality. Besides this, both the conventional rules on design and operation of power systems and the usual premises followed in energy efficiency programs (without mentioning the electricity consumed by the devices themselves) consider the sinusoidal voltage and current waveforms at the fixed fundamental frequency of the power grid. Thus, analysis of electricity consumption reductions in energy efficiency programs that include the use of PEs considers the reduction of kWh to the final consumer but not the additional losses caused by the increase in harmonic distortion. This article contributes to a better understanding of this problem by reporting the results of a case study of the ownership and use of television sets (TV sets) to estimate the economic impacts of residential PEs on a mainly residential electricity distribution system.
Grid Monitoring and Advanced Control of Distributed Power Generation Systems
DEFF Research Database (Denmark)
Timbus, Adrian Vasile
di erent types of controllers have been studied and compared. The possibility of using the information about grid variables into the control structure in order to improve the control of DPGS has also been investigated. As a consequence, improved behavior of resonant controller has been noticed if......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...... voltage phase angle. Has been found that identi cation of positive and negative sequence components and in addition, the capability of the algorithm to follow only the positive sequence component, plays a crucial role in providing a clean synchronization angle even during severe voltage unbalance caused...
Distribution grid reconfiguration reduces power losses and helps integrate renewables
International Nuclear Information System (INIS)
A reconfigurable network can change its topology by opening and closing switches on power lines. We use real wind, solar, load, and cost data and a model of a reconfigurable distribution grid to show that reconfiguration allows a grid operator to reduce operational losses as well as to accept more intermittent renewable generation than a static configuration can. Net present value analysis of automated switch technology shows that the return on investment is negative for this test network when considering only loss reduction, but that the investment is attractive under certain conditions when reconfiguration is used to minimize curtailment. - Highlights: ► Reconfiguration may reduce losses in grids with solar or wind distributed generation. ► Reconfigurable networks can accept more solar or wind DG than static ones. ► Using reconfiguration for loss reduction would not create a positive ROI. ► Using reconfiguration to reduce curtailment usually would create a positive ROI.
PDPKDES ( Pre Distributed Powerful Key for Data Encryption Standard)
Prerna Mittal; Bhawna Chauhan
2013-01-01
Data encryption standard in spite of being a great algorithm in terms of a good combination of confusion and diffusion steps, doesn’t largely used because of a weak key concept. The key used in DES is only 64 bits (or 56 bits) long. This paper introduces a concept of pre distributed powerful key for DES. In this for every round of DES a new key is getting used which makes cryptanalyst to attack not 56 bits but 16 keys of 56 bits each which makes it a much stronger algorithm.
PDPKDES ( Pre Distributed Powerful Key for Data Encryption Standard
Directory of Open Access Journals (Sweden)
Prerna Mittal
2013-06-01
Full Text Available Data encryption standard in spite of being a great algorithm in terms of a good combination of confusion and diffusion steps, doesn’t largely used because of a weak key concept. The key used in DES is only 64 bits (or 56 bits long. This paper introduces a concept of pre distributed powerful key for DES. In this for every round of DES a new key is getting used which makes cryptanalyst to attack not 56 bits but 16 keys of 56 bits each which makes it a much stronger algorithm.
Effect of Heterogeneity of JSFR Fuel Assemblies to Power Distribution
International Nuclear Information System (INIS)
Conclusion: 1) Strong heterogeneity of JSFR assemblies was successfully calculated by BACH. 2) Verification test of BACH: • Infinite assembly model; • Color set model; • Good agreement with Monte-Carlo results. 3) Core calculations 3 models for inner duct was used; inward model, outward model and homogeneous model. • keff difference between the inward and out ward model → 0.3%Δk; • ~20% effect on flux and power distributions. Therefore, we have to pay careful attention for the location of inner duct in fuel loading of JSFR
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. ...
Optimization of reliability electric power transmission and distribution networks
Directory of Open Access Journals (Sweden)
Dorin Sarchiz
2011-12-01
Full Text Available The problem of quality services provided by suppliers of electricity is currently a major problem due to significant economic implications given the complexity and cost of electric power transmission and distribution systems on the one hand and consumers on the other side who are becoming more demanding in regarding the quality of electricity supplied.Starting from this real situation, the paper develops nonlinear mathematical model of optimization of reliability through redundancy, knowing that according to literature, redundancy helps to increase system reliability.
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.
Power Law Distributions of Patents as Indicators of Innovation
O'Neale, Dion; Hendy, Shaun
2013-03-01
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. Such figures however give an overly simplistic measure of innovation within a country. Here we present evidence that the distribution of patents amongst applicants within many countries is well-fitted to a power law distribution 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.
Single-phase power distribution system power flow and fault analysis
Halpin, S. M.; Grigsby, L. L.
1992-01-01
Alternative methods for power flow and fault analysis of single-phase distribution systems are presented. The algorithms for both power flow and fault analysis utilize a generalized approach to network modeling. The generalized admittance matrix, formed using elements of linear graph theory, is an accurate network model for all possible single-phase network configurations. Unlike the standard nodal admittance matrix formulation algorithms, the generalized approach uses generalized component models for the transmission line and transformer. The standard assumption of a common node voltage reference point is not required to construct the generalized admittance matrix. Therefore, truly accurate simulation results can be obtained for networks that cannot be modeled using traditional techniques.
Dan Wang; Jiming Lu; Zixia Sang; Chengxiong Mao
2013-01-01
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 d...
Directory of Open Access Journals (Sweden)
Bahman Bahmanifirouzi
2012-03-01
Full Text Available This paper presents a new Fuzzy Adaptive Modified Particle Swarm Optimization algorithm (FAMPSO for the placement of Fuel Cell Power Plants (FCPPs in distribution systems. FCPPs, as Distributed Generation (DG units, can be considered as Combined sources of Heat, Power, and Hydrogen (CHPH. CHPH operation of FCPPs can improve overall system efficiency, as well as produce hydrogen which can be stored for the future use of FCPPs or can be sold for profit. The objective functions investigated are minimizing the operating costs of electrical energy generation of distribution substations and FCPPs, minimizing the voltage deviation and minimizing the total emission. In this regard, this paper just considers the placement of CHPH FCPPs while investment cost of devices is not considered. Considering the fact that the objectives are different, non-commensurable and nonlinear, it is difficult to solve the problem using conventional approaches that may optimize a single objective. Moreover, the placement of FCPPs in distribution systems is a mixed integer problem. Therefore, this paper uses the FAMPSO algorithm to overcome these problems. For solving the proposed multi-objective problem, this paper utilizes the Pareto Optimality idea to obtain a set of solution in the multi-objective problem instead of only one. Also, a fuzzy system is used to tune parameters of FAMPSO algorithm such as inertia weight. The efficacy of the proposed approach is validated on a 69-bus distribution system.
Reorganization of the power distribution sector in India
International Nuclear Information System (INIS)
This paper presents the central issues for electricity-sector reform in India, as they grew out of the reform process that began in 1991, and within the context of the sector's organization, regulatory structure, and other institutional characteristics. The paper argues that India's current reform policies will not be sufficient to achieve reliable, efficient power because distribution reform has not been done. Undertaking distribution reform is a difficult path to tread because of the absence of global consensus on best practices and conflicting forces, both economic and political. The paper analyzes alternative institutional structures for reform in the distribution sector. The findings include that the objectives of coverage and efficiency may conflict, that economically efficient reorganization may be politically unachievable and that the small, municipally owned firm may be the best compromise. Since many Indian states are economically and politically diverse from each other, and include both large served and unserved areas, there is scope to vary the organizational structure depending on the state's situation. This paper provides a means to do so. The agenda for policymakers is to identify the situation in their respective states and choose a reorganization path that is the best compromise
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.
Voltage multi-stability in distribution grids with power flow reversal
Nguyen, Hung D.; Turitsyn, Konstantin
2014-01-01
High levels of penetration of distributed generation and aggressive reactive power compensation with modern power electronics may result in the reversal of active and reactive power flows in future distribution grids. The voltage stability of these operating conditions may be very different from the more traditional power consumption regime. We study the stability characteristics of distribution networks with reversed power flow. After introducing a universal algebraic approach to characteriz...
Belgacem, O; Pittenauer, E; Openshaw, M E; Hart, P J; Bowdler, A; Allmaier, G
2016-01-01
Rationale For the last two decades, curved field reflectron technology has been used in matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometers, assisting in the generation of post-source-decay (PSD) or collision-induced dissociation (CID) without decelerating precursor ions, producing true high-energy CID spectra. The result was the generation of product ion mass spectra with product ions typical of high-energy (10 keV and beyond) collision processes. The disadvantage of this approach was the lack of resolution in CID spectra resulting from the excess laser energy deposition used to generate those MS/MS spectra. The work presented in this study overcomes this limitation and includes comprehensive examples of high-energy and high-resolution CID MALDI-MS/MS spectra of biomolecules. Methods The devices used in this study are TOF/RTOF instruments equipped with a high-vacuum MALDI ion source. High-resolution and high-energy CID spectra result from the use of axial spatial distribution focusing (ASDF) in combination with curved field reflectron technology. Results A CID spectrum of the P14R1 peptide exhibits product ion resolution in excess of 10,000 (FWHM) but at the same time yields typical high-energy product ions such as w- and [y–2]-type ion series. High-energy CID spectra of lipids, exemplified by a glycerophospholipid and triglyceride, demonstrate C–C backbone fragmentation elucidating the presence of a hydroxyl group in addition to double-bond positioning. A complex high mannose carbohydrate (Man)8(GlcNAc)2 was also studied at 20 keV collision energy and revealed further high-energy product ions with very high resolution, allowing unambiguous detection and characterization of cross-ring cleavage-related ions. Conclusions This is the first comprehensive study using a MALDI-TOF/RTOF instrument equipped with a curved field reflectron and an ASDF device prior to the reflectron. © 2015 The Authors. Rapid Communications in
Energy Technology Data Exchange (ETDEWEB)
NONE
1999-01-10
Aiming at earlier restoration of failures and further improvement of efficiency in control of power distribution system operation, Okinawa Electric Power and Fuji Electric have been proceeding with review of the specifications and functions of a power distribution automating system. Its partial operation has now begun by using a remote control system consisting mainly of remotely controlled operation of switches. The major features of the system may be summarized as follows: (1) it has two-console configuration capable of simultaneous parallel operation and continuation of operation even at server shutdown by using a man-machine workstation; (2) a simplified mapping system is adopted for indication of a distribution system chart, incorporating features of both of the mapping system and the skeleton system; (3) a simplified system operating function is employed, in which procedures of load switching and returning operations are prepared and executed automatically without a need of registering an event name; and (4) a system to memorize operation procedures for facility data maintenance is used to respond flexibly to sequence exchange of construction names and postponement of a construction. (NEDO)
Retinal ganglion cell distribution and spatial resolving power in elasmobranchs.
Lisney, Thomas J; Collin, Shaun P
2008-01-01
The total number, distribution and peak density of presumed retinal ganglion cells was assessed in 10 species of elasmobranch (nine species of shark and one species of batoid) using counts of Nissl-stained cells in retinal wholemounts. The species sampled include a number of active, predatory benthopelagic and pelagic sharks that are found in a variety of coastal and oceanic habitats and represent elasmobranch groups for which information of this nature is currently lacking. The topographic distribution of cells was heterogeneous in all species. Two benthic species, the shark Chiloscyllium punctatum and the batoid Taeniura lymma, have a dorsal or dorso-central horizontal streak of increased cell density, whereas the majority of the benthopelagic and pelagic sharks examined exhibit a more concentric pattern of increasing cell density, culminating in a central area centralis of higher cell density located close to the optic nerve head. The exception is the shark Alopias superciliosus, which possesses a ventral horizontal streak. Variation in retinal ganglion cell topography appears to be related to the visual demands of different habitats and lifestyles, as well as the positioning of the eyes in the head. The upper limits of spatial resolving power were calculated for all 10 species, using peak ganglion cell densities and estimates of focal length taken from cryo-sectioned eyes in combination with information from the literature. Spatial resolving power ranged from 2.02 to 10.56 cycles deg(-1), which is in accordance with previous studies. Species with a lower spatial resolving power tend to be benthic and/or coastal species that feed on benthic invertebrates and fishes. Active, benthopelagic and pelagic species from more oceanic habitats which feed on larger, more active prey, possess a higher resolving power. Additionally, ganglion cells in a juvenile of C. punctatum, were retrogradely-labeled from the optic nerve with biotinylated dextran amine (BDA). A comparison
Mohammad Hosein Rezaei; Rahmatolah Hooshmand; Mohammad Ataei
2011-01-01
Transformers perform many functions such as voltage transformation, isolation and noise decoupling. They are indispensable components in electric power distribution system. However, at low frequencies (50 Hz), they are one of the heaviest and the most expensive equipment in an electrical distribution system. Nowadays, electronic power transformers are used instead of conventional power transformers that do voltage transformation and power delivery in power system by power electronic converter...
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.
Optimization of power distribution networks; Optimierung von Energieverteilungsnetzen
Energy Technology Data Exchange (ETDEWEB)
Casteren, J. van [Digsilent GmbH (Netherlands); Chalmers Univ. of Technology, Goeteborg (Sweden)
2000-03-01
In a competition-oriented power market the optimization of distribution networks is more and more becoming a search for minimum investment and operating cost where all relevant cost factors should be taken into account. A so far neglected factor is the expectation of reliability-related cost. A new analytical calculation method permits flexible, realistic estimation of interruption costs to be expected. (orig.) [German] In einem wettbewerbsorientierten Strom-Markt wird die Optimierung der Verteilungsnetze mehr und mehr zu einer Suche nach den minimalen Investitions- und Betriebskosten, wobei moeglichst alle relevanten Kostenfaktoren beruecksichtigt werden muessen. Ein bisher vernachlaessigter Faktor ist dabei die Erwartung der zuverlaessigkeitsbedingten Kosten. Ein neues analytisches Berechnungsverfahren erlaubt nun flexibel eine realistische Abschaetzung der zu erwarteten Unterbrechungskosten. (orig.)
Leadership in Mammalian Societies: Emergence, Distribution, Power, and Payoff.
Smith, Jennifer E; Gavrilets, Sergey; Mulder, Monique Borgerhoff; Hooper, Paul L; El Mouden, Claire; Nettle, Daniel; Hauert, Christoph; Hill, Kim; Perry, Susan; Pusey, Anne E; van Vugt, Mark; Smith, Eric Alden
2016-01-01
Leadership is an active area of research in both the biological and social sciences. This review provides a transdisciplinary synthesis of biological and social-science views of leadership from an evolutionary perspective, and examines patterns of leadership in a set of small-scale human and non-human mammalian societies. We review empirical and theoretical work on leadership in four domains: movement, food acquisition, within-group conflict mediation, and between-group interactions. We categorize patterns of variation in leadership in five dimensions: distribution (across individuals), emergence (achieved versus inherited), power, relative payoff to leadership, and generality (across domains). We find that human leadership exhibits commonalities with and differences from the broader mammalian pattern, raising interesting theoretical and empirical issues. PMID:26552515
Nonperturbative features of the axial current
Kopeliovich, B Z; Siddikov, M
2013-01-01
In this paper we study the nonperturbative structure of the axial current and evaluate the two-point distribution amplitudes $\\int d\\xi\\, e^{-iq...\\xi}$ in the framework of the instanton vacuum model in the leading order in $\\mathcal{O}(N_{c})$. We perform a direct numerical test of the relations between the axial current and the pion distribution amplitudes, imposed by PCAC, and found excellent agreement.
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...
Distributed Control Systems in New Nuclear Power Plants
International Nuclear Information System (INIS)
With the growing demand for energy many countries have expressed interest in constructing new plants over the next 15 to 20 years. These expectations have presented a challenge to the nuclear industry to provide a high volume of construction. A key strategy to meet this challenge is developing an advanced nuclear power plant design that allows for a modular construction, a high level of standardization, passive safety features, reduced number of components, and a short bid-to-build time. In addition, the implementation of the plant control system has evolved as new technologies emerge to support these goals. The purpose of this paper is to discuss the ways that the distributed control and information systems in the new generation of nuclear power plants will differ from those currently in service. The new designs provide opportunities to improve overall performance through the use of bus technology, a video display driven Human System Interface, enhanced diagnostics and improved maintenance features. However, the new technologies must fully address requirements for cyber security and high reliability. This paper will give an overview of new technology, improvements, as well as emerging issues in new plant design. (authors)
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 in Afghanistan: The Padisaw micro-hydro project
International Nuclear Information System (INIS)
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)
Directory of Open Access Journals (Sweden)
Yin Yin Winn
2014-10-01
Full Text Available Due to the rapid development in automation system, control and monitoring are necessary for any modern system. DCS provides this control and monitoring for industrial automation. The system is designed and constructed Distributed Control System (DCS based power distribution in university campus. The research has constructed hardware and utilized Microsoft Visual Basic software in software environment using a communication network and embedded controllers. All hardware and software components have been developed and integrated together. Data exchange mechanism, USB cable has been developed between the host computer and the embedded controllers that function in two way data exchanges between the two. This system uses PIC 18F4550 microcontroller to collect electrical parameters of devices in each departments. The Graphical User Interface (GUI uses Visual Basic Software under Microsoft Visual Basic 2010 express to achieve data real-time display and status display for the loads.
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.
Design of a power management and distribution system for a thermionic-diode powered spacecraft
Kimnach, Greg L.
1996-01-01
The Electrical Systems Development Branch of the Power Technology Division at the NASA Lewis Research Center in Cleveland, Ohio is designing a Power Management and Distribution (PMAD) System for the Air Force's Integrated Solar Upper Stage (ISUS) Engine Ground Test Demonstration (EGD). The ISUS program uses solar-thermal propulsion to perform orbit transfers from Low Earth Orbit (LEO) to Geosynchronous Orbit (GEO) and from LEO to Molnya. The ISUS uses the same energy conversion receiver to perform the LEO to High Earth Orbit (HEO) transfer and to generate on-orbit electric power for the payloads. On-orbit power generation is accomplished via two solar concentrators heating a dual-cavity graphite-core which has Thermionic Diodes (TMD's) encircling each cavity. The graphite core and concentrators together are called the Receiver and Concentrator (RAC). The TDM-emitters reach peak temperatures of approximately 2200K, and the TID-collectors are run at approximately 1000K. Because of the high Specific Impulse (I(sup sp)) of solar thermal propulsion relative to chemical propulsion, and because a common bus is used for communications, GN&C, power, etc., a substantial increase in payload weight is possible. This potentially allows for a stepdown in the required launch vehicle size or class for similar payload weight using conventional chemical propulsion and a separate spacecraft bus. The ISUS power system is to provide 1000W(sub e) at 28+/-6V(sub dc) to the payload/spacecraft from a maximum TID generation capability of 1070W(sub e) at 2200K. Producing power with this quality, protecting the spacecraft from electrical faults and accommodating operational constraints of the TID's are the responsibilities of the PMAD system. The design strategy and system options examined along with the proposed designs for the Flight and EGD configurations are discussed herein.
RTDS-Based Design and Simulation of Distributed P-Q Power Resources in Smart Grid
Taylor, Zachariah David
In this Thesis, we propose to utilize a battery system together with its power electronics interfaces and bidirectional charger as a distributed P-Q resource in power distribution networks. First, we present an optimization-based approach to operate such distributed P-Q resources based on the characteristics of the battery and charger system as well as the features and needs of the power distribution network. Then, we use the RTDS Simulator, which is an industry-standard simulation tool of power systems, to develop two RTDS-based design approaches. The first design is based on an ideal four-quadrant distributed P-Q power resource. The second design is based on a detailed four-quadrant distributed P-Q power resource that is developed using power electronics components. The hardware and power electronics circuitry as well as the control units are explained for the second design. After that, given the two-RTDS designs, we conducted extensive RTDS simulations to assess the performance of the designed distributed P-Q Power Resource in an IEEE 13 bus test system. We observed that the proposed design can noticeably improve the operational performance of the power distribution grid in at least four key aspects: reducing power loss, active power peak load shaving at substation, reactive power peak load shaving at substation, and voltage regulation. We examine these performance measures across three design cases: Case 1: There is no P-Q Power Resource available on the power distribution network. Case 2: The installed P-Q Power Resource only supports active power, i.e., it only utilizes its battery component. Case 3: The installed P-Q Power Resource supports both active and reactive power, i.e., it utilizes both its battery component and its power electronics charger component. In the end, we present insightful interpretations on the simulation results and suggest some future works.
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....
Validating MCNP for LEU Fuel Design via Power Distribution Comparisons
Energy Technology Data Exchange (ETDEWEB)
Primm, Trent [ORNL; Maldonado, G Ivan [ORNL; Chandler, David [ORNL
2008-11-01
The mission of the Reduced Enrichment for Research and Test Reactors (RERTR) Program is to minimize and, to the extent possible, eliminate the use of highly enriched uranium (HEU) in civilian nuclear applications by working to convert research and test reactors, as well as radioisotope production processes, to low enriched uranium (LEU) fuel and targets. Oak Ridge National Lab (ORNL) is reviewing the design bases and key operating criteria including fuel operating parameters, enrichment-related safety analyses, fuel performance, and fuel fabrication in regard to converting the fuel of the High Flux Isotope Reactor (HFIR) from HEU to LEU. The purpose of this study is to validate Monte Carlo methods currently in use for conversion analyses. The methods have been validated for the prediction of flux values in the reactor target, reflector, and beam tubes, but this study focuses on the prediction of the power density profile in the core. A current 3-D Monte Carlo N-Particle (MCNP) model was modified to replicate the HFIR Critical Experiment 3 (HFIRCE-3) core of 1965. In this experiment, the power profile was determined by counting the gamma activity at selected locations in the core. Foils (chunks of fuel meat and clad) were punched out of the fuel elements in HFIRCE-3 following irradiation and experimental relative power densities were obtained by measuring the activity of these foils and comparing each foil s activity to the activity of a normalizing foil. The current work consisted of calculating corresponding activities by inserting volume tallies into the modified MCNP model to represent the punchings. The average fission density was calculated for each foil location and then normalized to the normalizing foil. Power distributions were obtained for the clean core (no poison in moderator and symmetrical rod position at 17.5 inches) and fully poisoned-moderator (1.35 g B/liter in moderator and rods fully withdrawn) conditions. The observed deviations between the
An Effective Distributed Model for Power System Transient Stability Analysis
MUTHU, B. M.; VEILUMUTHU, R.; PONNUSAMY, L.
2011-01-01
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 diff...
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.
Aging Management Guideline for commercial nuclear power plants: Power and distribution transformers
International Nuclear Information System (INIS)
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
Distributed power generation: A case study of small scale PV power plant in Greece
Energy Technology Data Exchange (ETDEWEB)
Bakos, G.C. [Democritus University of Thrace, Department of Electrical and Computer Engineering, Laboratory of Energy Economics, 67 100 Xanthi (Greece)
2009-09-15
In recent years, energy systems have been undergoing a development trend characterised by privatisation of the most important energy sectors (electricity and natural gas) that has turned former monopolies into free-market competitors. Furthermore, community awareness of environmental impact caused by large conventional power plants is growing, together with a greater interest in distributed-generation (DG) technologies based upon renewable energy sources (RES) and cogeneration. In this context, renewable energy technologies are emerging as potentially strong competitors for more widespread use. Despite the remarkable progress attained over the past decades, RES have not yet been fully integrated into the power sector. Some RES-technologies have already achieved a significant market share. The industry is now quite mature, although far from having developed its global potential. This paper deals with the current status of DG in Greece and the presentation of a 60 kWp PV power station, developed under Law 3468/06 ''Production of Electricity from Renewable Energy Sources, High Efficiency Cogeneration of Heat and Power and Other De{nu}ices''. This application is the first DG installation with fixed PV modules implemented in the country after the approval of Law 3468/06. Cash flow economic analysis of the developed DG installation is performed and the experiences related to the potential of DG in Greek electricity market is presented and discussed. (author)
The collision theory reaction rate coefficient for power-law distributions
Yin, Cangtao; Du, Jiulin
2014-01-01
The collision theory for power-law distributions and a generalized collision theory rate coefficient is studied when the reactions take place in nonequilibrium systems with power-law distributions. We obtain the power-law rate coefficient and by numerical analyses we show a very strong dependence of the rate coefficient on the power-law parameter. We find that the power-law collision theory can successfully overcome the two difficulties of Lindemann-Christiansen mechanism. We take three react...
Axial Vircator for Electronic Warfare Applications
Directory of Open Access Journals (Sweden)
L. Drazan
2009-12-01
Full Text Available This paper deals with a high power microwave generator with virtual cathode – vircator in axial release for electronic warfare applications. The classification of directed energy weapons microwave (DEWM is introduced together with basic block diagrams of a particular class of DEWM. In the paper, methods for designing vircator pulsed power supply, axial vircator structure, measurement methods and experimental results are presented. The vircator in electromagnetic ammunition is powered by magneto-cumulative generator and in weapons for defense of objects (WDO, it is powered by Marx generator. The possible applications of a vircator in the DEWM area are discussed.
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)
Review of modular power converters solutions for smart transformer in distribution system
DEFF Research Database (Denmark)
Alzola, Rafael Pena; Gohil, Ghanshyamsinh Vijaysinh; Mathe, Laszlo; Liserre, Marco; Blaabjerg, Frede
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...
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.
Cooperating expert systems for space station power distribution management
International Nuclear Information System (INIS)
In a complex system such as the manned Space Station, it is deemed necessary that many expert systems must perform tasks in a concurrent and cooperative manner. An important question to arise is: what cooperative-task-performing models are appropriate for multiple expert systems to jointly perform tasks. The solution to this question will provide a crucial automation design criteria for the Space Station complex systems architecture. Based on a client/server model for performing tasks, the authors have developed a system that acts as a front-end to support loosely-coupled communications between expert systems running on multiple Symbolics machines. As an example, they use the two ART*-based expert systems to demonstrate the concept of parallel symbolic manipulation for power distribution management and dynamic load planner/scheduler in the simulated Space Station environment. This on-going work will also explore other cooperative-task-performing models as alternatives which can evaluate inter and intra expert system communication mechanisms. It will serve as a testbed and a bench-marking tool for other Space Station expert subsystem communication and information exchange
Reactivity control rod for controlling reactor power distribution
International Nuclear Information System (INIS)
Since a cladding tube is situated at the outer side, it undergoes neutron irradiation in a reactor core and also undergoes compression force due to high pressure of reactor coolants to cause a creep phenomenon, and the diameter is reduced as it is used. Then, neutron absorbing rods as reactivity control rods for controlling the power distribution are constituted with a cladding tube, a spacer tube disposed at the central portion of the cladding tube and a borosilicate glass tube disposed between the cladding tube and the spacer tube. The gap between the borosilicate glass tube and the spacer tube is gradually changed so that the inner diameter of the borosilicate glass is increased as it comes closer to the lower end plug. The time of contact between the cladding tube and the spacer tube in the inside is delayed by the constitution of the borosilicate glass tube disposed in the cladding tube of the neutron absorbing rod as the reactivity control rod thereby capable of extending the integral working life time with no rupture of the cladding tube. (N.H.)
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...
Axial length variability in cataract surgery
International Nuclear Information System (INIS)
To determine the mean axial length and biometric measures in patients undergoing cataract surgery and further compare the variability of axial length between the gender and with age. Study Design: Cross-sectional observational study. Place and Duration of Study: Eye Unit I, Department of Ophthalmology, Liaquat University of Medical and Health Sciences, Hyderabad, Pakistan from January 2010 to December 2012. Methodology: All patients referred for cataract surgery were assessed. The study included 886 eyes which were straightforward cataract cases with no other ocular problem. The data was collected for axial length, keratometric values and Intra-Ocular Lens (IOL) power prior to cataract surgery. The collected data was then analyzed using SPSS version 19 for windows software. Results: Gender based comparison showed significant difference in age, axial length, keratometric values and IOL power between the two groups (p=0.000). 86% of the eyes had an axial length between 21.00 mm and 23.99 mm. In univariate analysis there was significant (p=0.000) relation between overall age and axial length. The keratometric values ranged between 36.75 D and 52.50 D. Majority of the IOL powers ranged between 20.00 D and 23.00 D. Conclusion: The mean axial length of patients undergoing cataract surgery was 22.96 +- 1.04 mm, was comparable to Indian and Chinese population but shorter than the Western population. Females had shorter axial lengths, similar to other studies. Axial length was positively associated with age among the females, the cause of which is yet to be determined. (author)
Mclallin, K. L.; Kofskey, M. G.; Wong, R. Y.
1982-01-01
An experimental evaluation of the aerodynamic performance of the axial flow, variable area stator power turbine stage for the Department of Energy upgraded automotive gas turbine engine was conducted in cold air. The interstage transition duct, the variable area stator, the rotor, and the exit diffuser were included in the evaluation of the turbine stage. The measured total blading efficiency was 0.096 less than the design value of 0.85. Large radial gradients in flow conditions were found at the exit of the interstage duct that adversely affected power turbine performance. Although power turbine efficiency was less than design, the turbine operating line corresponding to the steady state road load power curve was within 0.02 of the maximum available stage efficiency at any given speed.
Scholl, M. A.; Ingebritsen, S. E.; Essaid, H. I.
1993-02-01
Fox (1990), in order to explain observations during the Axial Seamount Hydrothermal Emissions Study (ASHES), proposed a conceptual model for a two-phase subsea hydrothermal system in which steam controlled flow patterns by blocking liquid flow. An attempt is made here to demonstrate with a very general model that relative permeability contrasts by themselves do not cause spatial isolation of phases in steam/liquid water systems and that density segregation, independent of relative permeability effects, should not be ruled out as an explanation for the observations at the ASHES site. Fox replies that density segregation is probably not the only mechanism at work.
Near-field angular distributions of high velocity ions for low-power hall thrusters
Sullivan, Regina M.; Yost, Allison; Johnson, Lee K.
2009-01-01
Experimental angular distributions of high-energy primary ions in the near-field region of a small Hall thruster between 50-200 mm downstream of the thruster exit plane at a range of centerline angles have been determined using a highly-collimated, energy-selective diagnostic probe. The measurements reveal a wide angular distribution of ions exiting the thruster channel and the formation of a strong, axially-directed jet of ions along the thruster centerline. Comparisons are made to other exp...
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
Evaluation of 3-D Power Distribution Synthesis Method for SMART Core Monitoring System
International Nuclear Information System (INIS)
A 3-dimensional power distribution synthesis method, named DPCM3D has been developed by KAERI. SMART core monitoring system, SCOMS adopted this method instead of Fourier expansion method for the digital monitoring system of conventional PWRs. The DPCM3D method produces a synthetic 3-D power distribution by coupling a neutronics code and measured in-core detector signals. In DPCM3D, instrumented node powers are determined from the detector powers by using power sharing factors and the un-instrumented node powers are determined by using power connection factors. A coefficient library for the 3-D power synthesis is functionalized as a function of the burnup, core power and control rod position. In this paper, performance of SCOMS 3-D power distribution synthesis method for SMART initial core was evaluated
Power Quality Improvement in Distribution System using ANN Based Shunt Active Power Filter
Directory of Open Access Journals (Sweden)
Somlal Jarupula
2015-02-01
Full Text Available This paper focuses on an Artificial Neural Network (ANN controller based Shunt Active Power Filter (SAPF for mitigating the harmonics of the distribution system. To increase the performance of the conventional controller and take advantage of smart controllers, a feed forward-type (trained by a back propagation algorithm ANN-based technique is implemented in shunt active power filters for producing the controlled pulses required for IGBT inverter. The proposed approach mainly work on the principle of capacitor energy to maintain the DC link voltage of a shunt connected filter and thus reduces the transient response time when there is abrupt variation in the load. The entire power system block set model of the proposed scheme has been developed in MATLAB environment. Simulations are carried out by using MATLAB, it is noticed that the %THD is reduced to 2.27% from 29.71% by ANN controlled filter. The simulated experimental results also show that the novel control method is not only easy to be computed and implemented, but also very successful in reducing harmonics.
Study on axial offset oscillation for WWER-1000 reactor by using WWER-1000 simulator
International Nuclear Information System (INIS)
In the operation of thermal neutron reactors, it is known that the spatial xenon oscillations arise frequently. The nature of these oscillations is that almost of power concentrate just at a small region in the reactor core volume. The characteristic parameter for the axial power distribution is axial offset. In this subject, the cause of axial offset oscillation and its characteristics are studied. We investigate axial offset oscillation in begin of fuel cycle (BOC) and end of fuel cycle (EOC) of loading 1 enrichment and loading 5 enrichment for WWER-1000 reactor, using WWER-1000 reactor simulation program that was originally developed by IAEA. The results are: (1) the formation of axial offset oscillation is due to periodic deviation from an equilibrium distribution of iodine, xenon and neutron flux density between the upper half and the lower half of the reactor core, when the control group number 1 is inserted into the bottom of reactor core; (2) regarding the same fuel enrichment, in BOC, offset oscillates with larger amplitude and slower damping than in EOC. On the other hand, in higher fuel enrichment, offset oscillates with smaller amplitude and quicker damping than in lower fuel enrichment. (author)
Bode, Hans R.
2009-01-01
Morphogen gradients play an important role in pattern formation during early stages of embryonic development in many bilaterians. In an adult hydra, axial patterning processes are constantly active because of the tissue dynamics in the adult. These processes include an organizer region in the head, which continuously produces and transmits two signals that are distributed in gradients down the body column. One signal sets up and maintains the head activation gradient, which is a morphogenetic gradient. This gradient confers the capacity of head formation on tissue of the body column, which takes place during bud formation, hydra's mode of asexual reproduction, as well as during head regeneration following bisection of the animal anywhere along the body column. The other signal sets up the head inhibition gradient, which prevents head formation, thereby restricting bud formation to the lower part of the body column in an adult hydra. Little is known about the molecular basis of the two gradients. In contrast, the canonical Wnt pathway plays a central role in setting up and maintaining the head organizer. PMID:20066073
International Nuclear Information System (INIS)
A new method which can give continuous guidance for controlling axial xenon oscillations in large PWRs has been presented. The method is based on two additional newly defined axial offsets, A Oi and A Ox together with the conventional axial offset of power distribution A Op. A Oi and A Ox are the axial offsets of power distributions which would give the current iodine and xenon distributions under equilibrium conditions, respectively. The information from A Oi, A Ox and A Op are used to display the trajectory of (A Op - A Ox, A Oi - A Ox) in the X-Y plane. The trajectory shows a very characteristic behavior. With the characteristics in mind the xenon oscillation can be controlled quite easily to lead the plot to the origin where three A Os are identical. The method has been proved with the power level constant. However, it is necessary to modify the definition of A Ox so as to apply this method to load following operations. A reasonable way of the modification is described and the results are presented. (author)
Hooshyar, Hossein; Vanfretti, Luigi
2013-01-01
Power flow analysis on a Photovoltaic System (PV)dominated distribution network is rather different than a conventional distribution system. This paper proposes a new three-phase power flow solution for such networks that considers the multiphase unbalanced nature of distribution systems together with different system topologies. Power flow contributions of PVs and different types of loads are also considered. The performance of the proposed method has been assessed by simulations on a sample...
Furusawa, Chikara; Kaneko, Kunihiko
2005-01-01
The evolutionary origin of universal statistics in biochemical reaction network is studied, to explain the power-law distribution of reaction links and the power-law distributions of chemical abundances. Using cell models with catalytic reaction network, we find evidence that the power-law distribution in abundances of chemicals emerges by the selection of cells with higher growth speeds. Through the further evolution, this inhomogeneity in chemical abundances is shown to be embedded in the d...
Analysis of Capacitor Placement in Power Distribution Networks Using Body Immune Algorithm
Majid Davoodi; Mohsen Davoudi; Iraj Ganjkhany; Morteza Arfand; Ali Aref
2012-01-01
In this study we present a new technique for analysis of capacitor placement in the power distribution systems considering the most of the parameters affected in this problem. Detection of capacitance and optimal placement of capacitors in power distribution system can lead to decrement in losses, enhancement in voltage profile, increment of power factor and freeing up generation capacityand energy distribution. The majority of literatures pay more attention to solve this problem considering ...
Distributed Low-Complexity Controller for Wind Power Plant in Derated Operation
DEFF Research Database (Denmark)
Biegel, Benjamin; Madjidian, Daria; Spudic, Vedrana; Rantzer, Anders; Stoustrup, Jakob
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 that...
Relay Protection Coordination for Photovoltaic Power Plant Connected on Distribution Network
Nikolovski, Srete; Papuga, Vanja; Knežević, Goran
2014-01-01
This paper presents a procedure and computation of relay protection coordination for a PV power plant connected to the distribution network. In recent years, the growing concern for environment preservation has caused expansion of photovoltaic PV power plants in distribution networks. Numerical computer simulation is an indispensable tool for studying photovoltaic (PV) systems protection coordination. In this paper, EasyPower computer program is used with the module Power Protector. Time-curr...
A distributed control strategy for reactive power compensation in smart microgrids
Bolognani, Saverio; Zampieri, Sandro
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 then consider the specific problem of commanding the microgenerators connected to the microgrid, in order to achieve the optimal injection of reactive power. For this t...
Distributed reactive power feedback control for voltage regulation and loss minimization
Bolognani, Saverio; Cavraro, Guido; Carli, Ruggero; Zampieri, Sandro
2013-01-01
We consider the problem of exploiting the microgenerators dispersed in the power distribution network in order to provide distributed reactive power compensation for power losses minimization and voltage regulation. In the proposed strategy, microgenerators are smart agents that can measure their phasorial voltage, share these data with the other agents on a cyber layer, and adjust the amount of reactive power injected into the grid, according to a feedback control law that descends from dual...
Enhancement of Voltage Stability & reactive Power Control of Distribution System Using Facts Devices
Aarti Rai
2012-01-01
The modern power distribution network is constantly being faced with an ever-growing load demand. Distribution networks experience distinct change from a low to high load level every day. Electric load growth and higher regional power transfers in a largely interconnected network becoming more complex and less secure power system operation. Power generation and transmission facilities are unable to meet these new demands. Voltage control is a difficult task because voltages are strongly influ...
Kramers escape rate in overdamped systems with the power-law distribution
Zhou, Yanjun; Du, Jiulin
2014-01-01
Kramers escape rate in the overdamped systems with the power-law distribution is studied. By using the mean first passage time, we derive the escape rate for the power-law distribution and obtain the Kramers' infinite barrier escape rate in this case. It is shown that the escape rate for the power-law distribution extends the Kramers' overdamped result to the relatively low barrier. Furthermore, we apply the escape rate for the power-law distribution to the unfolding of titin and show a bette...
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.
Research and design of distributed intelligence fault diagnosis system in nuclear power plant
International Nuclear Information System (INIS)
In order to further reduce the misoperation after the faults occurring of nuclear power plant, according to the function distribution of nuclear power equipment and the distributed control features of digital instrument control system, a nuclear power plant distributed condition monitoring and fault diagnosis system was researched and designed. Based on decomposition-integrated diagnostic thinking, a fuzzy neural network and RBF neural network was presented to do the distributed local diagnosis and multi-source information fusion technology for the global integrated diagnosis. Simulation results show that the developed distributed status monitoring and fault diagnosis system can diagnose more typical accidents of PWR to provide effective diagnosis and operation information. (authors)
Bohnenstiehl, D. R.; Howell, J. K.; Hey, R. N.
2008-12-01
Deep-towed DSL-120 bathymetric data are used to investigate the pattern of lava dome formation along a superfast spreading portion of the southern East Pacific Rise (EPR), including the overlapping limbs of a giant (120 × 120 km) propagator near 29°S. Along the 670 km of the axis surveyed, 1172 small domes were identified using a closed contour algorithm. Their abundance, defined by spatial density, is well correlated with the along-axis relief of the ridge crest. Where the western and eastern limbs plunge toward the overlap zone, densities are high (3-6 km-2); however, where the axial depth profile is shallow and flat, densities are comparably low (0.4 km-2). Volcanic domes within the low abundance areas are characterized by lower ratios of height to basal radius (0.15 versus 0.22), smaller maximum heights (18 versus 40 m), and a larger relative percentage of small versus large mounds. The zone of high dome abundance encompasses the overlapping limbs of the rift and extends more than 100 km to the north and south beyond the overlap zone. Domes form dominantly during low effusion rate, point-source eruptions, which suggests that discontinuous melt lenses underlie the ridge axis proximal to the overlapper. Conversely, fissure-fed sheet flows dominate along the more distal segments, implying the presence of a more continuous axial magma lens. Throughout the survey area, dome abundance increases systematically near second-order segment boundaries. Within the high abundance zone, some third-order offsets also correlate with increased dome production, but local peaks in abundance are not tied exclusively to higher-order ridge offsets. Where dome abundance is low, domes are clustered tightly near second-order offsets and there is no increase in dome abundance near third-order segment boundaries.
The influence of decision power on distributive fairness
Julian Rode; Marc Le Menestrel
2011-01-01
We study the influence of decision power on fairness in the division of gains from productive activity. In an experimental setting, two actors are involved in generating a gain, but only one contributes actively by completing a task. In three treatments, decision power to divide the gain is assigned to (1) the inactive, (2) both the inactive and the active, (3) the active participant. Results show that changes in decision power not only affect allocations in accordance with previous research,...
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 power demand is flattened. The network model describes how the information of power imbalance of individual agents can be exchanged in the system. Additionally, dynamics, washing machine constraints an...
Electric power distribution: in the direction of a competitive market?
International Nuclear Information System (INIS)
This paper discusses the process of electric power sector deregulation, occurred in several countries, frequently followed of privatization, which the aim is activate the competition and, consequently, the efficiency between the companies of the electric power sector. The competition in the supply market of electric power, by the Great Britain, France, Spain and United States are shown as an example of this energy policy. (C.G.C.)
Impact of electric vehicles on power distribution networks
Putrus, Ghanim; Suwanapingkarl, Pasist; Johnston, David; Bentley, Edward; Narayana, Mahinsasa
2009-01-01
The market for battery powered and plug-in hybrid electric vehicles is currently limited, but this is expected to grow rapidly with the increased concern about the environment and advances in technology. Due to their high energy capacity, mass deployment of electrical vehicles will have significant impact on power networks. This impact will dictate the design of the electric vehicle interface devices and the way future power networks will be designed and controlled. This paper presents the re...
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.
Improving Power Quality in Low-Voltage Networks Containing Distributed Energy Resources
Mazumder, Sumit; Ghosh, Arindam; Zare, Firuz
2013-05-01
Severe power quality problems can arise when a large number of single-phase distributed energy resources (DERs) are connected to a low-voltage power distribution system. Due to the random location and size of DERs, it may so happen that a particular phase generates excess power than its load demand. In such an event, the excess power will be fed back to the distribution substation and will eventually find its way to the transmission network, causing undesirable voltage-current unbalance. As a solution to this problem, the article proposes the use of a distribution static compensator (DSTATCOM), which regulates voltage at the point of common coupling (PCC), thereby ensuring balanced current flow from and to the distribution substation. Additionally, this device can also support the distribution network in the absence of the utility connection, making the distribution system work as a microgrid. The proposals are validated through extensive digital computer simulation studies using PSCADTM.
Signatures for axial chromodynamics
International Nuclear Information System (INIS)
Within the context of basic left-right symmetry and the hypothesis of unification of weak, electromagnetic and strong forces at a mass level approximately equal to 104-106 GeV, relatively light ''mass'' axial gluons, confined or liberated, must be postulated. The authors remark that the existence of such ''light'' axial gluons supplementing the familiar vector octet preserves the successes of QCD, both for deep inelastic processes and charmonium physics. Through the characteristic spin-spin force, generated by their exchange, they may even help resolve some of the discrepancies between vector QCD predictions and charmonium physics. The main remark of this note is that if colour is liberated, not only vector but also axial-vector gluons are produced in high-energy e-e+ experiments, e.g. at PETRA and PEP, with fairly large cross-section. Distinctive decay modes of such liberated axial gluons are noted
DEFF Research Database (Denmark)
Chen, Shuheng; Hu, Weihao; Chen, Zhe
2016-01-01
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...
Surface nanoscale axial photonics
Sumetsky, M.; Fini, J. M.
2011-01-01
Dense photonic integration promises to revolutionize optical computing and communications. However, efforts towards this goal face unacceptable attenuation of light caused by surface roughness in microscopic devices. Here we address this problem by introducing Surface Nanoscale Axial Photonics (SNAP). The SNAP platform is based on whispering gallery modes circulating around the optical fiber surface and undergoing slow axial propagation readily described by the one-dimensional Schr\\"odinger e...
Time-frequency analyses of disturbances in power distribution systems
Avdakovic, Samir; Bosovic, Adnan; Hasanspahic, Nedzad; Saric, Kenan
2014-01-01
Future smart distribution grids will apart from a large number of measurement instruments, communication infrastructure, intelligent software etc., also require the appropriate techniques for analysis of the available signals. Various disturbances of different intensities constantly occur in real distribution systems. Many of them are just temporary while others cause the tripping of protection devices and the suspension of electricity supply. For distribution network operators, timely identi...
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.
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.
Wind Power Forecasting Error Distributions: An International Comparison
DEFF Research Database (Denmark)
Hodge, Bri-Mathias; Lew, Debra; Milligan, Michael;
2012-01-01
Wind power forecasting is essential for greater penetration of wind power into electricity systems. Because no wind forecasting system is perfect, a thorough understanding of the errors that may occur is a critical factor for system operation functions, such as the setting of operating reserve le...
Topology investigation of front end DC/DC converter for distributed power system
Yang, Bo
2003-01-01
Topology Investigation of Front End DC/DC Power Conversion for Distributed Power System by Bo Yang Fred C. Lee, Chairman Electrical Engineering (Abstract) With the fast advance in VLSI technology, smaller, more powerful digital system is available. It requires power supply with higher power density, lower profile and higher efficiency. PWM topologies have been widely used for this application. Unfortunately, hold up time requirement put huge penalties on the performance o...
Tag, Andreas; Bader, Bernhard; Huck, Christian; Karolewski, Dominik; Pitschi, Maximilian; Weigel, Robert; Hagelauer, Amelie
2015-10-01
The modeling of bulk acoustic wave resonators at elevated power levels has been improved by taking the spatial distribution of the dominating loss mechanisms into account. The spatial distribution of the dissipated power enables more accurate modeling of the temperature increase caused by the applied power. Thus, it is also possible to more accurately model the frequency shifts of the resonators' impedance curves resulting from the temperature increase caused by the applied power. Simulation and measurement results for the temperatures and impedances of the resonators with different layerstacks at high power loads are presented. The simulation and measurement results are in good agreement, confirming the presented modeling approach. Furthermore, the de-embedding procedure used to obtain vectorial scattering parameters of the resonators during high power loads, the according measurement setup, and the procedure for measuring absolute temperatures by infrared thermography are discussed. PMID:26470048
Axial Force at the Vessel Bottom Induced by Axial Impellers
I. Fořt; P. Hasal; A. Paglianti; F. Magelli
2008-01-01
This paper deals with the axial force affecting the flat bottom of a cylindrical stirred vessel. The vessel is equipped with four radial baffles and is stirred with a four 45° pitched blade impeller pumping downwards. The set of pressure transducers is located along the whole radius of the flat bottom between two radial baffles. The radial distribution of the dynamic pressures indicated by the transducers is measured in dependence on the impeller off-bottom clearance and impeller speed.It fol...
A Review of Parallel Operation of Active Power Filters in the Distributed Generation System
Khadem, Shafiuzzaman Khan; Basu, Malabika; Conlon, Michael
2011-01-01
In this paper a technical review of parallel operation of Active Power Filter (APF) for harmonic power compensation in distributed generation (DG) network has been presented. Controlling methods and connection topologies with their pros and cons are described. Recent improvements in controlling and future trends for the application of APFs in distributed mode are also identified.
Hybrid reactor blankets for constant energy multiplication and flat power distribution
International Nuclear Information System (INIS)
Two blanket design difficulties are usually attributed to the blanket neutronic properties: high peak-to-average power density ratio distribution and the variation of the energy multiplication with burnup. This work shows that blankets can be designed to have a constant energy multiplication and a flat power distribution. These features are illustrated for light water hydrid reactor blankets
Schilling, D. L.; Oh, S. J.; Thau, F.
1975-01-01
Developments in communications systems, computer systems, and power distribution systems for the space shuttle are described. The use of high speed delta modulation for bit rate compression in the transmission of television signals is discussed. Simultaneous Multiprocessor Organization, an approach to computer organization, is presented. Methods of computer simulation and automatic malfunction detection for the shuttle power distribution system are also described.
Development of An On-Line, Core Power Distribution Monitoring System
International Nuclear Information System (INIS)
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 estimation 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
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
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...... 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....
Power system services provided by inverter connected distributed energy resources
Isleifsson, Fridrik Rafn
2011-01-01
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 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...
Energy Technology Data Exchange (ETDEWEB)
Jatuff, F.; Krouthen, J.; Helmersson, S.; Chawla, R
2004-03-01
A significant source of uncertainty in Boiling Water Reactor physics is associated with the precise characterisation of the axially-dependent neutron moderation properties of the coolant inside the fuel assembly channel, and the corresponding effects on reactor physics parameters such as the lattice neutron multiplication, the neutron migration length, and the pin-by-pin power distribution. In this paper, the effects of particularly relevant void fraction uncertainties on reactor physics parameters have been studied for a BWR assembly of type Westinghouse SVEA-96 using the CASMO-4, HELIOS/PRESTO-2 and MCNP4C codes. The SVEA-96 geometry is characterised by the sub-division of the assembly into four different sub-bundles by means of an inner bypass with a cruciform shape. The study has covered the following issues: (a) the effects of different cross-section data libraries on the void coefficient of reactivity, for a wide range of void fractions; (b) the effects due to a heterogeneous vs. homogeneous void distribution inside the sub-bundles; and (c) the consequences of partly inserted absorber blades producing different void fractions in different sub-bundles. (author)
Broadband from the socket and privatization of power distribution networks
International Nuclear Information System (INIS)
Attention is paid to the consequences for the Dutch market of the recommendation of the European Commission to introduce Power Line Communication (PLC) in the EU member states. PLC makes it possible to access the internet via sockets
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
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 an autonomous and online control structure for finite-inertia power systems (dc and ac) with a...
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...
Control strategies for power distribution networks with electric vehicles integration.
Hu, Junjie; Østergaard, Jacob; Lind, Morten
2014-01-01
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. EVs can absorb energy during periods of high electricity production and feed the electricity back into the grid when the demand is high or in situations of insucient electricity generation. However, e...
Digital Control of Converters for Distributed Power Generations
Skjellnes, Tore
2008-01-01
Pulse width modulated converters are becoming increasingly popular as their cost decreases and power rating increases. The new trend of smallscale 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 vol...
A Concept Plane using electric distributed propulsion Evaluation of advanced power architecture
Ridel, M.; Paluch, B.; Doll, C.; Donjat, D.; Hermetz, J.; Guigon, A.; Schmollgruber, P.; Atinault, O.; Choy, P.; Le Tallec, P.; Dessornes, O.; Lefebvre, T
2015-01-01
Starting from electrical distributed propulsion system concept, the ONERA’s engineers demonstrated the viability of an all electrical aircraft for a small business aircraft. This paper describes the advanced power architecture considering energy conversion and power distribution. The design of this advanced power architecture requires the multi-physic integration of different domains as flight performances, safety and environmental requirements (thermal, electric, electromagnetic). From this ...
Electrical Load Forecasting in Power Distribution Network by Using Artificial Neural Network
Ali Nahari; Habib Rostami; Rahman Dashti
2013-01-01
Today, one of most important concerns in electrical power markets and distribution network is supplying the customer demands. In order to manage the market it is necessary to forecast the usage of electrical power in distribution network. The pattern of electrical power usage depends on many different parameters such as the week days, seasons, weather condition and etc. Today, researchers by using an artificial intelligence based on the natural intelligence are trying to forecast the costumer...
Power-law distribution functions derived from maximum entropy and a symmetry relationship
Peterson, G. J.; Dill, K. A.
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...
Low Power at Different levels of VLSI Design an clock Distribution Schemes
Chetan Sharma
2011-01-01
Low power chip requirement in the VLSI industry is main considerable field due to the reduction of chip dimension day by day and environmental factors. In this paper various low power techniques at Gate level, Architecture level and different tradeoffs between different clock distribution schemes like as single driver clock scheme and distributed buffers clock scheme are reviewed. Here it is also tried to showing various effects of particular clock distribution scheme such as clock skew, cloc...
Transition state theory: a generalization to nonequilibrium systems with power-law distributions
Du, Jiulin
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-...
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...
The MLP Distribution: A Modified Lognormal Power-Law Model for the Stellar Initial Mass Function
Basu, Shantanu; Auddy, Sayantan
2015-01-01
This work explores the mathematical properties of a distribution introduced by Basu & Jones (2004), and applies it to model the stellar initial mass function (IMF). The distribution arises simply from an initial lognormal distribution, requiring that each object in it subsequently undergoes exponential growth but with an exponential distribution of growth lifetimes. This leads to a modified lognormal with a power-law tail (MLP) distribution, which can in fact be applied to a wide range of fields where distributions are observed to have a lognormal-like body and a power-law tail. We derive important properties of the MLP distribution, like the cumulative distribution, the mean, variance, arbitrary raw moments, and a random number generator. These analytic properties of the distribution can be used to facilitate application to modeling the IMF. We demonstrate how the MLP function provides an excellent fit to the IMF compiled by Chabrier (2005) and how this fit can be used to quickly identify quantities like...
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.
On distributive effects of optimal regulation for power grid expansion
International Nuclear Information System (INIS)
To date, the distributive implications of incentive regulation on electricity transmission networks have not been explicitly studied in the literature. More specifically, the parameters that a regulator might use to achieve distributive efficiency under price-cap regulation have not yet been identified. To discern these parameters is the motivation for the research presented in this paper. We study how different weight parameters affect the distributive characteristics of optimal price-cap incentive regulation for electricity transmission. We find that a regulator's use of ideal (Laspeyres) weights tends to be more beneficial for the Transco (consumers) than for consumers (the Transco). - Highlights: • Distributive implications of incentive regulation on transmission networks have not been studied in the literature. • The parameters that a regulator might use to achieve distributive efficiency have so far not been explicitly analyzed. • Analyze how different weights affect the distributive characteristics of price-cap regulation in electricity transmission. • Results: ideal (Laspeyres) weights tend to be more beneficial for the Transco (consumers) than for consumers (the Transco)
Optimization of residual heat removal pump axial thrust and axial bearing
Energy Technology Data Exchange (ETDEWEB)
Schubert, F.
1996-12-01
The residual heat removal (RHR) pumps of German 1300 megawatt pressurized-water reactor (PWR) power plants are of the single stage end suction type with volute casing or with diffuser and forged circular casing. Due to the service conditions the pumps have to cover the full capacity range as well as a big variation in suction static pressure. This results in a big difference in the axial thrust that has to be borne by the axial bearing. Because these pumps are designed to operate without auxiliary systems (things that do not exist can not fail), they are equipped with antifriction bearings and sump oil lubrication. To minimize the heat production within the bearing casing, a number of PWR plants have pumps with combined axial/radial bearings of the ball type. Due to the fact that the maximum axial thrust caused by static pressure and hydrodynamic forces on the impeller is too big to be borne by that type of axial bearing, the impellers were designed to produce a hydrodynamic axial force that counteracts the static axial force. Thus, the resulting axial thrust may change direction when the static pressure varies.
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
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.
Degree-degree distribution in a power law random intersection graph with clustering
Bloznelis, Mindaugas
2014-01-01
The bivariate distribution of degrees of adjacent vertices (degree-degree distribution) is an important network characteristic defining the statistical dependencies between degrees of adjacent vertices. We show the asymptotic degree-degree distribution of a sparse inhomogeneous random intersection graph and discuss its relation to the clustering and power law properties of the graph.
Site selection and evaluation for nuclear power plants with respect to population distribution
International Nuclear Information System (INIS)
This safety guide, relating population distribution to site selection and evaluation, for nuclear power plants, forms part of the IAEA's programme, referred to as the NUSS programme (Nuclear Safety Standards). The guide presents population distribution data, requirements, examples of site screening methods, and an overview of radiological impact assessment with respect to population distribution
CFD Simulation of Casing Treatment of Axial Flow Compressors
DeWitt, Kenneth
2005-01-01
A computational study is carried out to understand the physical mechanism responsible for the improvement in stall margin of an axial flow rotor due to the circumferential casing grooves. It is shown that the computational tool used predicts an increase in operating range of the rotor when casing grooves are present. A budget of the axial momentum equation is carried out at the rotor casing in the tip gap in order to uncover the physical process behind this stall margin improvement. It is shown that for the smooth casing the net axial pressure force . However in the presence of casing grooves the net axial shear stress force acting at the casing is augmented by the axial force due to the radial transport of axial momentum, which occurs across the grooves and power stream interface. This additional force adds to the net axial viscous sheer force and thus leads to an increase in the stall margin of the rotor.
Optimal power flow management for distributed energy resources with batteries
International Nuclear Information System (INIS)
Highlights: • A PV-diesel-battery hybrid system is proposed. • Model minimizes fuel and battery wear costs. • Power flows are analysed in a 24-h period. • Results provide a practical platform for decision making. - Abstract: This paper presents an optimal energy management model of a solar photovoltaic-diesel-battery hybrid power supply system for off-grid applications. The aim is to meet the load demand completely while satisfying the system constraints. The proposed model minimizes fuel and battery wear costs and finds the optimal power flow, taking into account photovoltaic power availability, battery bank state of charge and load power demand. The optimal solutions are compared for cases when the objectives are weighted equally and when a larger weight is assigned to battery wear. A considerable increase in system operational cost is observed in the latter case owing to the increased usage of the diesel generator. The results are important for decision makers, as they depict the optimal decisions considered in the presence of trade-offs between conflicting objectives
International Nuclear Information System (INIS)
Amphibian malformations have recently received much attention from the scientific community, but few studies have provided evidence linking environmental pollution to larval amphibian malformations in the field. The authors document an increased incidence of axial malformations in bullfrog larvae (Rana catesbeiana) inhabiting two sites contaminated with coal combustion wastes. In the polluted sites, 18 and 37% of larvae exhibited lateral curvatures of the spine, whereas zero and 4% of larvae from two reference sites had similar malformations. Larvae from the most heavily polluted site had significantly higher tissue concentrations of potentially toxic trace elements, including As, Cd, Se, Cu, Cr, and V, compared with conspecifics from the reference sites. In addition, malformed larvae from the cost contaminated site had decreased swimming speeds compared with those of normal larvae from the same site. The authors hypothesize that the complex mixture of contaminants produced by coal combustion is responsible for the high incidence of malformations and associated effects on swimming performance
Geometry of Power Flows and Optimization in Distribution Networks
Lavaei, Javad; Tse, David; Zhang, Baosen
2012-01-01
We investigate the geometry of injection regions and its relationship to optimization of power flows in tree networks. The injection region is the set of all vectors of bus power injections that satisfy the network and operation constraints. The geometrical object of interest is the set of Pareto-optimal points of the injection region. If the voltage magnitudes are fixed, the injection region of a tree network can be written as a linear transformation of the product of two-bus injection regio...
Power distribution faced with the challenges posed by competition
International Nuclear Information System (INIS)
The introduction of liberalization, the increasing share of decentralized electricity generation, the aging of electrical infrastructures, ambitious generation objectives and technological evolution are the key drivers that require substantial investments in the distribution grid. The most urgent challenges are to adapt the network architecture and operation, modernize and improve metering equipment, renovate existing facilities. The Energy Regulatory Commission sets the price to be paid by users of the distribution grid; this price is set rather low, in order to encourage the system operator to make productivity gains. But resultant low income may deprive the operator of the financial resources needed to adapt the system to the new conditions. (authors)
Directory of Open Access Journals (Sweden)
Runhai Jiao
2015-01-01
Full Text Available This paper puts forward a novel particle swarm optimization algorithm with quantum behavior (QPSO to solve reactive power optimization in power system with distributed generation. Moreover, differential evolution (DE operators are applied to enhance the algorithm (DQPSO. This paper focuses on the minimization of active power loss, respectively, and uses QPSO and DQPSO to determine terminal voltage of generators, and ratio of transformers, switching group number of capacitors to achieve optimal reactive power flow. The proposed algorithms are validated through three IEEE standard examples. Comparing the results obtained from QPSO and DQPSO with those obtained from PSO, we find that our algorithms are more likely to get the global optimal solution and have a better convergence. What is more, DQPSO is better than QPSO. Furthermore, with the integration of distributed generation, active power loss has decreased significantly. Specifically, PV distributed generations can suppress voltage fluctuation better than PQ distributed generations.
Validation of CITVAP Power Distribution via the IAEA 3-D PWR Benchmark Problem
International Nuclear Information System (INIS)
Calculation of effective multiplication factor (keff) value and power distribution is a very important task for fuel assembly design and whole core safety analysis. In this work, used deterministic method used with CITVAP v 3.1 code , which is based on the diffusion theory with finite difference method, to assess the accuracy of keff calculation and power distribution of the IAEA 3-D PWR benchmark problem. The study of power maps achieve on fuel assembly-by-assembly level. The code results for keff value and power map distribution are compared with reference values. The results demonstrate that the CITVAP v 3.1 codes showed good estimates of both keff value and power distribution for the critical core benchmark provided adequate number of meshes is chosen per each assembly
Rod bundle axial non-uniform heat flux DNB tests and data
International Nuclear Information System (INIS)
A description is given of an extensive experimental program performed to investigate the behavior of Departure from Nucleate Boiling (DNB) in electrically heated rod bundles simulating a portion of a nuclear power reactor assembly. Effects on DMB due to non-uniform axial heat flux distribution, heater rod lengths, rod spacer grids with and without mixing vane and axial grid spacing were investigated. The experimental parameters investigated were pressure, inlet temperature, and inlet mass velocity. The 284 DNB data points obtained were compared with DNB heat fluxes predicted by the non-uniform heat flux W-3 correlation (with spacer factor) which is based on single channel data. The predicted DNB heat flux values were based on local conditions calculated by the THINC computer code. The results verified that this correlation can accurately predict the DNB heat fluxes in axially non-uniform heat flux rod bundles. (auth)
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.
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.
Electrical Market Management Considering Power System Constraints in Smart Distribution Grids
Poria Hasanpor Divshali; Bong Jun Choi
2016-01-01
Rising demand, climate change, growing fuel costs, outdated power system infrastructures, and new power generation technologies have made renewable distribution generators very attractive in recent years. Because of the increasing penetration level of renewable energy sources in addition to the growth of new electrical demand sectors, such as electrical vehicles, the power system may face serious problems and challenges in the near future. A revolutionary new power grid system, called smart g...
Axial channeling of boron ions into silicon
La Ferla, A.; Galvagno, G.; Raineri, V.; Setola, R.; Rimini, E.; Carbera, A.; Gasparotto, A.
1992-04-01
Channeling boron implants were performed into (100) and (110) silicon substrates in the energy range 80-700 keV. The dose ranged between 3.5 × 10 11 and 1 × 10 15 atoms/cm 2. The axial channeling concentration profiles of implanted B + were compared with that obtained for incidence along the random direction of the crystal and with that obtained by implantation in amorphous silicon. The electrical and chemical boron distributions were obtained by spreading resistance and secondary ion mass spectrometry measurements, respectively. The inelastic stopping power, Sc, was extracted from the experimental maximum ranges for the [100] and [110] axis. The energ dependence of the electronic stopping power is given by Sc = KEp with p[100] = 0.469±0.010 and p[110] = 0.554±0.004. Simulations obtained by the MARLOWE code, using the Oen-Robinson impact parameter dependent formula, for the electronic energy loss reproduce quite well the experimental depth profiles.
Axial channeling of boron ions into silicon
International Nuclear Information System (INIS)
Channeling boron implants were performed into (100) and (110) silicon substrates in the energy range 80-700 keV. The dose ranged between 3.5x1011 and 1x1015 atoms/cm2. The axial channeling concentration profiles of implanted B+ were compared with that obtained for incidence along the random direction of the crystal and with that obtained by implantation in amorphous silicon. The electrical and chemical boron distributions were obtained by spreading resistance and secondary ion mass spectrometry measurements, respectively. The inelastic stopping power, Sc, was extracted from the experimental maximum ranges for the [100] and [110] axis. The energy dependence of the electronic stopping power is given by Se = KEp with p[100] = 0.469±0.010 and p[110] = 0.554±0.004. Simulations obtained by the MARLOWE code, using the Oen-Robinson impact parameter dependent formula, for the electronic energy loss reproduce quite well the experimental depth profiles. (orig.)
Axial channeling of boron ions into silicon
Energy Technology Data Exchange (ETDEWEB)
La Ferla, A.; Galvagno, G. (Ist. di Tecnologie e Metodologie per la Microelettronica, CNR, Dipt. di Fisica, Catania (Italy)); Raineri, V.; Setola, R.; Rimini, E. (Dipt. di Fisica, Univ. di Catania (Italy)); Carnera, A.; Gasparotto, A. (Dipt. di Fisica, Univ. di Padova (Italy))
1992-04-01
Channeling boron implants were performed into (100) and (110) silicon substrates in the energy range 80-700 keV. The dose ranged between 3.5x10{sup 11} and 1x10{sup 15} atoms/cm{sup 2}. The axial channeling concentration profiles of implanted B{sup +} were compared with that obtained for incidence along the random direction of the crystal and with that obtained by implantation in amorphous silicon. The electrical and chemical boron distributions were obtained by spreading resistance and secondary ion mass spectrometry measurements, respectively. The inelastic stopping power, S{sub c}, was extracted from the experimental maximum ranges for the (100) and (110) axis. The energy dependence of the electronic stopping power is given by S{sub e} = KE{sup p} with p{sub (100)} = 0.469{+-}0.010 and p{sub (110)} = 0.554{+-}0.004. Simulations obtained by the MARLOWE code, using the Oen-Robinson impact parameter dependent formula, for the electronic energy loss reproduce quite well the experimental depth profiles. (orig.).
网壳屋面杆件轴力在地震波下的动力响应分析%On Axial Force Distribution of Squsre Pyrsmid Grids Roof Attacked
Institute of Scientific and Technical Information of China (English)
袁光英
2012-01-01
Through project case, this paper discusses on axial force distribution of square pyramid space grids roof attacked by El-Centro seismic wave by dynamic response analysis, so as to be reference for design of square pyramid space grids structure and seismic research.%通过工程实例，采用线性动力时程分析法对网壳结构进行在El-centro地震波下的动力响应分析，得到了网壳屋面的轴力分布规律，为网壳结构的设计以及地震研究提供参考。
Signals and Power Distribution in the CMS Inner Tracker
D'Alessandro, Raffaello; Fiore, Luigi; Liuzzi, A; Moggi, Andrea
2009-01-01
\\begin{abstract} This Note describes how the interconnection between the 3540 modules of the CMS Inner Tracker has been approached, focusing on the signal, high voltage and low voltage line distribution. The construction and tests of roughly a thousand interconnects called ``Mother Cables" is described. \\end{abstract}
Grid support by power electronic converters of distributed generation units
Morren, J.
2006-01-01
An increasing number of small Distributed Generation (DG) units are connected to the grid. The introduction of DG causes several problems, which are mainly related to the differences between DG units and conventional generators. Four problems have been considered in this thesis: damping of harmonics
Directory of Open Access Journals (Sweden)
F. Aguilar Parés
1999-01-01
Full Text Available Durante el movimiento de un material en un transportador de sinfín surge una fuerza en dirección axial que influye en laselección de uno de los cojinetes de apoyo del equipo. En el artículo aparecen algunas soluciones constructivas que tienen encuentan la fuerza axial. Por otro lado se establece la relación entre la fuerza axial y el empuje axial y se precisa de quiendepende el sentido del empuje axial. Por último se propone un modelo matemático que relaciona la fuerza axial con la potenciarequerida por el equipo.Palabras claves: Transportador de sinf in, fuerza axial , empuje axial ._________________________________________________________________________AbstractDuring the movement of material in a screw conveyor surge a force in axial direction that influence in the selection of one ofthe equipment support bearings. Some constructive solutions appear in the article for considering the axial force. In the otherhand it is established the relation between axial force and axial thurst and it is precised whose direction thurst axial depend of.Finally it is proposed a mathematic model that relates the axial force with the power required by the equipment.Key words: Screw conveyor, axial force, axial thurst .
Ross, Nathan
2013-01-01
For a family of linear preferential attachment graphs, we provide rates of convergence for the total variation distance between the degree of a randomly chosen vertex and an appropriate power law distribution as the number of vertices tends to infinity. Our proof uses a new formulation of Stein's method for the negative binomial distribution, which stems from a distributional transformation that has the negative binomial distributions as the only fixed points.
The origin of power-law distributions in self-organized criticality
Yang, C. B.
2004-01-01
The origin of power-law distributions in self-organized criticality is investigated by treating the variation of the number of active sites in the system as a stochastic process. An avalanche is then regarded as a first-return random walk process in a one-dimensional lattice. Power law distributions of the lifetime and spatial size are found when the random walk is unbiased with equal probability to move in opposite directions. This shows that power-law distributions in self-organized critica...
Development of Ada language control software for the NASA power management and distribution test bed
Wright, Ted; Mackin, Michael; Gantose, Dave
1989-01-01
The Ada language software developed to control the NASA Lewis Research Center's Power Management and Distribution testbed is described. The testbed is a reduced-scale prototype of the electric power system to be used on space station Freedom. It is designed to develop and test hardware and software for a 20-kHz power distribution system. The distributed, multiprocessor, testbed control system has an easy-to-use operator interface with an understandable English-text format. A simple interface for algorithm writers that uses the same commands as the operator interface is provided, encouraging interactive exploration of the system.
Case study : power distribution PBR plans of National Grid USA
International Nuclear Information System (INIS)
This power point presentation described the progressive approach taken by the Northeastern United States towards electric power restructuring and performance based ratemaking (PBR) with reference to National Grid USA and the NEES tradition of pursuing regulatory matters. The catalyst for change was the NEES acquisition of EUA (and National Grid USA acquisition of NEES). Another catalyst for change was the desire to merge operating companies and consolidate rates. This paper described the settlement negotiations of the New England Process with reference to meeting the customer's desire for lower electricity prices and rate stability.The paper also described a multi-year PBR-based plan proposed for Niagara Mohawk which offers incentives for both cost efficiency and service quality. It was concluded that PBR is a sound basis for optimizing customer and shareholder benefits. It was emphasized that while PBR has universal application, detailed implementation must be sensitive to local issues and priorities. tabs., figs
International organizations as a profession: Professional mobility and power distribution
Coicaud, Jean-Marc
2006-01-01
The role of international organizations grows with the acceleration of globalization and the increasing importance of global governance. However, thus far, only limited and rather narrow research has been generated on the subject. It is a state of affairs that reflects on international studies, as well as on the power realities of the world. By assessing international organizations through the career prospects that they offer to skilled professionals, this paper is an attempt to remedy this s...
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
of units -investment cost- and the technical losses in the system under study. The results obtained from the assessed test system show how such non-linear methods could help distribution system operators to obtain a fast and precise perception of what is the best way to integrate the Power......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...
Energy Technology Data Exchange (ETDEWEB)
Moon, Sang Ki; Cho, Seok; Chun, Se Young; Park, Jong Kuk; Kim, Bok Deuk; Youn, Young Jung; Baek, Won Pil
2004-05-01
An experimental study of the Critical Heat Flux (CHF) has been performed for a water flow in a non-uniformly heated vertical 3x3 rod bundle under low flow and a wide range of pressure conditions. Since most of experimental studies on the low flow CHF have been performed under low pressure conditions, present study has investigated the effects of various parameters on the CHF under low flow and a wide range of pressure conditions. Especially, these experiments are focused on the CHF under Return-To-Power (RTP) conditions that are expected to occur in a main steam line break accident of Pressurized Water Reactors (PWRs). Using present CHF data, the applicability of conventional CHF correlations are investigated in a return-to-power condition. The CHF data have been collected for system pressures ranging from 0.47 to 15.06 MPa, mass flux from 49.66 to 654.44 kg/m{sup 2}s, inlet subcooling from 67.90 to 722.70 kJ/kg and exit quality from 0.36 to 1.29. In this study, the return-to-power conditions are defined as conditions with low mass flux less than 250 kg/m{sup 2}s, intermediated pressure between 6.0 MPa and 12.0 MPa, and high inlet subcooling greater than 200 kJ/kg. Total 299 CHF data including 93 CHF data in return-to-power conditions are obtained. The effects of various parameters on the CHF are consistent with previous understandings on the round tube CHF. Conventional CHF correlations predict the present return-to-power CHF data with reasonable accuracies. However, the prediction capabilities become worse in a very low mass flux below than about 100 kg/m{sup 2}s.
Control strategies for power distribution networks with electric vehicles integration
DEFF Research Database (Denmark)
Hu, Junjie
vehicle eet operators to eliminate the grid congestion problem. Note that the electric vehicle eet operator can manage the EVs based on the three aforementioned control strategies. To test and evaluate the proposed control strategies, multi-agent concepts is used to model the price coordinated...... hierarchical scheduling system. To implement and demonstrate the multi-agent systems, a novel simulation platform has been developed based on the integration of JACK (a Java based agent-oriented development environment) and Matlab/Simulink software....... control, market based control, and price control. The thesis investigates new approaches for distribution networks congestion management. It suggests and develops a market based control for distribution grid congestion management. The general equilibrium market mechanism is utilized in the operation...
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.
Stationarity of the inter-event power-law distributions
Gandica, Yerali; Carvalho, Joao; 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 s...
Improved axial flux shape generator for quick DNB test
International Nuclear Information System (INIS)
Axial power shapes that develop during power maneuvering in pressurized water reactors must be analyzed to ensure that adequate margin to avoid departure from nucleate boiling (DNB) is maintained during these transients. In order to reduce the number of flux shapes that need to be analyzed in detail to determine DNB ratio (DNBR), often generic axial flux shapes are analyzed and Maximum Allowable Peaking (MAP) limits are determined to conservatively filter those actual axial power shapes that are clearly safe. Current generic MAP limits, obtained for axial flux shapes, generated by a two-parameter based axial flux shape generator, are overly conservative for some power shapes and nonconservative for others leading to unnecessary operational restrictions on conservative cases. A penalty is imposed on nonconservative cases. In order to reduce the number of overly conservative and nonconservative cases, the authors have developed a new generic axial power shape generator, that is based on three parameters. Generic MAP limits have been developed for the new axial flux shape generator and tested using real flux shapes by plotting the percent deviation of MAP limits for generic flux shapes from the corresponding value for actual flux shapes. New axial flux shape generator, which is clearly superior as it leads to significantly lower percent deviation, will lead to reduced man-hours for detailed DNBR analyses and remove some of the unnecessary operational restrictions imposed by the old flux shape generator
The Power of Heterogeneity: Parameter Relationships from Distributions
Röding, Magnus; Bradley, Siobhan J.; Williamson, Nathan H.; Dewi, Melissa R.; Nann, Thomas; Nydén, Magnus
2016-01-01
Complex scientific data is becoming the norm, many disciplines are growing immensely data-rich, and higher-dimensional measurements are performed to resolve complex relationships between parameters. Inherently multi-dimensional measurements can directly provide information on both the distributions of individual parameters and the relationships between them, such as in nuclear magnetic resonance and optical spectroscopy. However, when data originates from different measurements and comes in different forms, resolving parameter relationships is a matter of data analysis rather than experiment. We present a method for resolving relationships between parameters that are distributed individually and also correlated. In two case studies, we model the relationships between diameter and luminescence properties of quantum dots and the relationship between molecular weight and diffusion coefficient for polymers. Although it is expected that resolving complicated correlated relationships require inherently multi-dimensional measurements, our method constitutes a useful contribution to the modelling of quantitative relationships between correlated parameters and measurements. We emphasise the general applicability of the method in fields where heterogeneity and complex distributions of parameters are obstacles to scientific insight. PMID:27182701
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.
Research on intelligent monitor for 3D power distribution of reactor core
International Nuclear Information System (INIS)
Highlights: • Core power distribution of ex-core measurement system has been reconstructed. • Building up an artificial intelligence model for 3-D core power distribution. • Error of the experiments has been reduced to 0.76%. • Methods for improving the accuracy of the model have been obtained. - Abstract: A real-time monitor for 3D reactor power distribution is critical for nuclear safety and high efficiency of NPP’s operation as well as for optimizing the control system, especially when the nuclear power plant (NPP) works at a certain power level or it works in load following operation. This paper was based on analyzing the monitor for 3D reactor power distribution technologies used in modern NPPs. Furthermore, considering the latest research outcomes, the paper proposed a method based on using an ex-core neutron detector system and a neural network to set up a real time monitor system for reactor’s 3D power distribution supervision. The results of the experiments performed on a reactor simulation machine illustrated that the new monitor system worked very well for a certain burn-up range during the fuel cycle. In addition, this new model could reduce the errors associated with the fitting of the distribution effectively, and several optimization methods were also obtained to improve the accuracy of the simulation model
Impact of electric vehicle loads on electric power distribution systems
Buchh, Tariq Aslam
The voltages and currents on four distribution sites (FPLsb-1 to FPLsb-4) have been monitored. The load behavior with and without the EV load has been recorded. By performing laboratory tests on the GMC EV1 charger charging a fully discharged battery, the characteristics of the charger have been determined. The harmonic spectrum of the transformer current charging a fully discharged battery has been determined. The snap shots of the current and voltage waveforms have been recorded and studied. Based on the laboratory data a computer model of the charger and the distribution system has been developed. Comparing the simulation results to the laboratory results and the field data the simulation results have been validated. The simulated currents are roughly 4 to 10% away from the field recorded currents, in their magnitude and distortion. Based on the field data, laboratory results and the simulation results the derating of the distribution transformer has been calculated. The two methods suggested for the calculation of derating have been presented and compared. The maximum and minimum limits of derating have been suggested. Using the first method the maximum derating is 20% and the minimum value is 99%. Using the modified method the derating remains close to 99% throughout the charging cycle. (11 must be noted here, that a derating to 20% means that the transformer can safely handle only 20% of its full rated load. Likewise a derating to 99% means that the transformer can handle 99% of its full rated capacity. Thus, a transformer derated to 20% is highly derated and a transformer derated to 99% is slightly derated.) After establishing the reliability of the simulation, by comparing the simulation results with the field data and laboratory results, a charging scenario with shorter charging times (45 minutes and 1.2 hours) has been simulated. The distribution transformer derating corresponding to these short-charging times has been calculated and presented
Power distribution gradients and fuel pin failure root causes in WWER-1000 cores
International Nuclear Information System (INIS)
The purpose of this work consists in the influence investigation of some heterogeneities and construction materials on space power distribution in WWER-1000 type cores, especially from viewpoint of the values and gradient occurrence that could result in static loads with some consequences, e.g., fuel pin (FP) or fuel assembly (FA) bowing and possible contribution to the FP failure root causes. Since detailed power distribution cannot be obtained in nuclear power plants, needed information is provided by means of experiments on research reactors - in this case on LR-0. Two cases were investigated concerning the: 1. Power distribution inside of FPs neighbouring a FP containing gadolinium (Gd2O3) burnable absorber integrated into fuel. For this purpose an evaluation method based on mathematical modelling and numerical approximation was proposed by means of that, and using measured (integral) power release in selected fuel pins, some information about power release inside of needed (investigated) fuel pin can be obtained. Application of this method is demonstrated on investigated FPs neighbouring a FP with gadolinium by means of the relative azimuthal power distribution estimation on their pellet surface in horizontal plane and 2. Power distribution in FAs situated on the periphery of the WWER-1000 type cores, neighbouring the baffle (thermal shielding). Similar information can be used for code validation and FP failure occurrence investigation. (author)