A new strategy of axial power distribution control based on three axial offsets concept
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
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
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)
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
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
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
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
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
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
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
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
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
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
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)
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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)
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.
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
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
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
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
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
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
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.
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
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
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
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
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
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
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
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.
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
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
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 ...
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
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
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
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.
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
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.
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
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
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
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
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
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
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
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
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
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
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
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)
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
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
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
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
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
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
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
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
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
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
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.
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
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
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
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
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)
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)
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
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
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
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. ...
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
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
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...
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
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
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
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
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
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 ...
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.
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
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
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
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
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...
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
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
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
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
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
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.
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
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
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
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
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
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
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...
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
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
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
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.
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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...