A new strategy of axial power distribution control based on three axial offsets concept
International Nuclear Information System (INIS)
We have proposed a very simple control procedure for axial xenon oscillation control based on a characteristic trajectory. The trajectory is drawn by three offsets of power distributions, namely, AOp, AOi and AOx. They are defined as the offset of axial power distribution, the offset of the power distribution under which the current iodine distribution is obtained as the equilibrium and that for xenon distribution, respectively. When these offsets are plotted on X-Y plane for (AOp-AOx, AOi-AOx) the trajectory draws a quite characteristic ellipse (or an elliptic spiral). On the other hands, Constant Axial Offset Control (CAOC) procedure is adopted as axial power distribution control strategy during both base load and load following operations in domestic PWRs. In the previous paper, we have presented an innovative procedure of axial power distribution control during load following in PWRs based on this trajectory such that the AOp-AOx is to be controlled to zero when the value deviates the pre-determined limiting values. In this paper we propose a modified control strategy to get more stability of axial power distributions. In this strategy, we control the trajectory to be close to the major axis of the ellipse when the power distribution reaches the limiting values. In other words, the plot is not controlled only to reduce AOp-AOx but also AOi-AOx is taken into account at the same time. It is known that when the plot is controlled to the major axis, it means that the point gives the peak position of axial xenon oscillation. Therefore xenon oscillation will not increase its amplitude any more. Thus more stable axial power distribution control is attained. This kind of design concept is quite important especially for the future PWRs with elongated fuel length and longer core life. Because in a longer effective core and also the longer core life, it has been known that the stability of axial xenon oscillation becomes more unstable. In this paper, some simulation
Average incore axial power distribution measurement by a multi excore detector
International Nuclear Information System (INIS)
French 1300 MWe reactors Protection System against DNB and excessive linear power is based on the average incore axial power distribution continuous measurement by multi-excore detectors. This paper describes the main results obtained during the first power escalation of PALUEL Unit 1 and 2, first units of 1300 MWe reactors and shows some INCORE/EXCORE power distribution comparisons. (author)
Axial power distribution calculation using a neural network in the nuclear reactor core
Energy Technology Data Exchange (ETDEWEB)
Kim, Y. H.; Cha, K. H.; Lee, S. H. [Korea Electric Power Research Institute, Taejon (Korea, Republic of)
1997-12-31
This paper is concerned with an algorithm based on neural networks to calculate the axial power distribution using excore detector signals in the nuclear reactor core. The fundamental basis of the algorithm is that the detector response can be fairly accurately estimated using computational codes. In other words, the training set, which represents relationship between detector signals and axial power distributions, for the neural network can be obtained through calculations instead of measurements. Application of the new method to the Yonggwang nuclear power plant unit 3 (YGN-3) shows that it is superior to the current algorithm in place. 7 refs., 4 figs. (Author)
International Nuclear Information System (INIS)
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)
International Nuclear Information System (INIS)
Procedures are described for maintaining the axial offset value of the core, as an indicia of the axial power distribution, substantially equal to a target value, which is modified periodically to account for core burnup. In one embodiment a neutron absorbing element within the core coolant, or moderator, is employed to assist control of reactivity changes associated with changes in power with the full length control rods mainly employed to adjust variations in the axial power distribution, while the part length rods remain completely withdrawn from the fuel region of the core. In a second embodiment reactivity changes associated with changes in power are controlled by the full length rods, while the part length rods are used to adjust the axial power distribution and the neutron absorbing element within the core coolant or moderator is used to compensate for xenon buildup or depletion. (author)
Uniform versus Nonuniform Axial Power Distribution in Rod Bundle CHF Experiments
Directory of Open Access Journals (Sweden)
Baowen Yang
2014-01-01
Full Text Available Rod bundle experiments with axially uniform and nonuniform heat fluxes are examined to explore the potential limitations of using uniform rod bundle CHF data for CHF correlation development of light water reactors with nonuniform axial power distribution (APD. The case of upstream burnout is presented as an example of unique phenomena associated with nonuniform rod bundle CHF experiments. It is a result from combined effect of axial nonuniform power shape and different interchannel mixing mechanisms. In addition, several key parameters are investigated with respect to their potential impacts on the thermal-hydraulic behaviors between rod bundles with uniform and nonuniform APDs. This type of misrepresentation cannot be amended or compensated through the use of correction factors due to the lack of critical information in the uniform rod bundle CHF testing as well as the fundamental difference in the underlining driving mechanisms. Other potential issues involved with the use of uniform rod bundle CHF data for nonuniform APD system applications also present strong evidence concerning the limitations and inadequacy of using uniform rod bundle CHF data for the correlation, prediction, and design limit calculation for safety analysis.
Axial power flow distributions of ultrasonic guided waves in viscous liquid-filled pipes
Institute of Scientific and Technical Information of China (English)
TA Dean
2004-01-01
The axial power flow (APF) magnitude and attenuation distributions of ultrasonic longitudinal guided waves in viscous liquid-filled elastic pipes are investigated. The optimal location, optimal mode and its frequency-thickness product (fd) for the test of pipes filled with viscous liquid are chosen according to APF and attenuation distributions. The results show that the APF magnitude distribution is an important parameter in choosing the modes and parameters. A particular mode has weak dispersion in ranges of fd values with large group velocity, while other modes with smaller group velocity in the same fd ranges have stronger dispersion. It has been observed that, within these ranges, the chosen mode has a larger APF on the pipe's wall. Therefore, in the region of fd values where a particular mode has a large group velocity, this mode will be effective to be used in testing elastic pipes filled with viscous liquid. The results obtained from both the APF analysis and attenuation distribution are consistent.
International Nuclear Information System (INIS)
Measurements of relative power distributions were made using the γ-scanning method in the partially simulated cores of the axially heterogeneous FBR in order to study power flattening by introducing the inner blanket at core midplane and power distortion by insertion of simulated B4C control rod in the core. Power peaking factor was decreased by about 12 % in FCA XII-1 assembly in comparison with FCA XI-1 assembly, and the value was 1.11 +- 1.4 %. Distortion in power distribution caused by introducing the simulated B4C control rod in the FCA XII-1 assembly was obtained from the measured power distributions and propagation distance of the distortion was examined. It was observed that the inner blanket played a role to cease the propagation of distortion from the upper to lower half assembly. Calculations were made for all cores. Calculated results predict the measured results fairly well in the core region and inner blanket. A large descripancy remains in the outer blanket. (author)
International Nuclear Information System (INIS)
Presented here is a new numerical nodal method for the simulation of the axial power distribution within nuclear reactors using the one-dimensional one speed kinetics diffusion model with one group of delayed neutron precursors. Our method is based on a spectral analysis of the nodal kinetics equations. These equations are obtained by integrating the original kinetics equations separately over a time step and over a spatial node, and then considering flat approximations for the forward difference terms. These flat approximations are the only approximations that are considered in the method. As a result, the spectral nodal method for space - time reactor kinetics generates numerical solutions for space independent problems or for time independent problems that are completely free from truncation errors. We show numerical results to illustrate the method's accuracy for coarse mesh calculations. (author)
Effect of axial heat flux distribution on CHF
Energy Technology Data Exchange (ETDEWEB)
Park, Cheol
2000-10-01
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.
Axial power monitoring uncertainty in the Savannah River Reactors
International Nuclear Information System (INIS)
The results of this analysis quantified the uncertainty associated with monitoring the Axial Power Shape (APS) in the Savannah River Reactors. Thermocouples at each assembly flow exit map the radial power distribution and are the primary means of monitoring power in these reactors. The remaining uncertainty in power monitoring is associated with the relative axial power distribution. The APS is monitored by seven sensors that respond to power on each of nine vertical Axial Power Monitor (APM) rods. Computation of the APS uncertainty, for the reactor power limits analysis, started with a large database of APM rod measurements spanning several years of reactor operation. A computer algorithm was used to randomly select a sample of APSs which were input to a code. This code modeled the thermal-hydraulic performance of a single fuel assembly during a design basis Loss-of Coolant Accident. The assembly power limit at Onset of Significant Voiding was computed for each APS. The output was a distribution of expected assembly power limits that was adjusted to account for the biases caused by instrumentation error and by measuring 7 points rather than a continuous APS. Statistical analysis of the final assembly power limit distribution showed that reducing reactor power by approximately 3% was sufficient to account for APS variation. This data confirmed expectations that the assembly exit thermocouples provide all information needed for monitoring core power. The computational analysis results also quantified the contribution to power limits of the various uncertainties such as instrumentation error
Review of Axial Burnup Distribution Considerations for Burnup Credit Calculations
Energy Technology Data Exchange (ETDEWEB)
Wagner, J.C.; DeHart, M.D.
2000-03-01
This report attempts to summarize and consolidate the existing knowledge on axial burnup distribution issues that are important to burnup credit criticality safety calculations. Recently released Nuclear Regulatory Commission (NRC) staff guidance permits limited burnup credit, and thus, has prompted resolution of the axial burnup distribution issue. The reactivity difference between the neutron multiplication factor (keff) calculated with explicit representation of the axial burnup distribution and keff calculated assuming a uniform axial burnup is referred to as the ``end effect.'' This end effect is shown to be dependent on many factors, including the axial-burnup profile, total accumulated burnup, cooling time, initial enrichment, assembly design, and the isotopics considered (i.e., actinide-only or actinides plus fission products). Axial modeling studies, efforts related to the development of axial-profile databases, and the determination of bounding axial profiles are also discussed. Finally, areas that could benefit from further efforts are identified.
Review of Axial Burnup Distribution Considerations for Burnup Credit Calculations
International Nuclear Information System (INIS)
This report attempts to summarize and consolidate the existing knowledge on axial burnup distribution issues that are important to burnup credit criticality safety calculations. Recently released Nuclear Regulatory Commission (NRC) staff guidance permits limited burnup credit, and thus, has prompted resolution of the axial burnup distribution issue. The reactivity difference between the neutron multiplication factor (keff) calculated with explicit representation of the axial burnup distribution and keff calculated assuming a uniform axial burnup is referred to as the ''end effect.'' This end effect is shown to be dependent on many factors, including the axial-burnup profile, total accumulated burnup, cooling time, initial enrichment, assembly design, and the isotopics considered (i.e., actinide-only or actinides plus fission products). Axial modeling studies, efforts related to the development of axial-profile databases, and the determination of bounding axial profiles are also discussed. Finally, areas that could benefit from further efforts are identified
Institute of Scientific and Technical Information of China (English)
刘玉燕; 李玉红; 王恒
2014-01-01
针对二代压水堆核电厂轴向功率分布多为操作员手动调节的现状，提出了一种棒位调节和硼酸浓度调节相结合的反应堆功率和轴向功率分布的自动控制策略。基于 SIMULINK 建立了能够描述温度反馈效应、氙毒效应和轴向功率分布的双点堆模型，以及所设计的控制系统模型，并针对反应堆慢速斜坡降升功率和快速斜坡降升功率两种情况进行了仿真实验。仿真结果表明所提控制策略有较好的控制品质，负荷跟踪的超调量小于1%，轴向功率偏差进入轴向偏差参考带之内的时间小于5000秒。%The reactor power and axial power distribution automatic control strategy which com-bines rod position adjustment with boric acid concentration regulation is put forward for the status that axial power distribution of two generation pressurized water reactor nuclear power plant is adjusted by operator manually. A double-point reactor model and the control system model which can describe the temperature feedback,the effects of xenon and axial power distribution are established based on SIMU-LINK. The simulation results for reactor slow and fast slope lifting power show that the proposed control strategy has better control quality. Load tracking overshoot is less than 1%. The time for axial power dif-ference into reference tape is less than 5000 seconds.
Electric power distribution handbook
Short, Thomas Allen
2003-01-01
Of the ...big three... components of the electricity infrastructure, distribution typically gets the least attention, and no thorough, up-to-date treatment of the subject has been published in years. Filling that void, the Electric Power Distribution Handbook provides comprehensive information on the electrical aspects of power distribution systems. It is an unparalleled source for the background information, hard-to-find tables, graphs, methods, and statistics that power engineers need, and includes tips and solutions for problem solving and improving performance. In short, this handbook giv
International Nuclear Information System (INIS)
During load following operation of PWRs, it is required to control the changes of core power distribution and reactivity effectively. Since occurrence of xenon spatial distribution oscillation following the change of the reactor power can cause oscillation in the power distribution, one strategy for the core power distribution control is by eliminating xenon oscillation as fast as possible. A lot of studies have been done to solve the problem, some of which use complex mathematical treatments. On the other hand, the three axial offsets trajectory method, which uses a simple mathematical treatment based on two points reactor model, has been proved to be effective for xenon oscillation control. In this study, we examined the feasibility of application of the three axial offsets trajectory method as a strategy generator for the reactor control in the load following operation
Electric power distribution handbook
Short, Thomas Allen
2014-01-01
Of the ""big three"" components of electrical infrastructure, distribution typically gets the least attention. In fact, a thorough, up-to-date treatment of the subject hasn't been published in years, yet deregulation and technical changes have increased the need for better information. Filling this void, the Electric Power Distribution Handbook delivers comprehensive, cutting-edge coverage of the electrical aspects of power distribution systems. The first few chapters of this pragmatic guidebook focus on equipment-oriented information and applications such as choosing transformer connections,
Axial flux distribution in a lattice position in the NRX reactor
International Nuclear Information System (INIS)
The axial thermal flux distribution in a lattice position in the NRX reactor has been measured at a number of moderator levels. The results have been fitted to sine functions and values are given for the positions of the flux maxima and the extrapolated flux lengths. Results of measurements of the axial fast flux distribution are also given. (author)
Axial distribution of absorbed doses in fast neutron field at the RB reactor
International Nuclear Information System (INIS)
The coupled fast thermal system CFTS at the RB reactor is created for obtaining fast neutron fields. The axial distribution of fast neutron flux density in its second configuration (CFTS-2) is measured. The axial distribution of absorbed doses is computed on the basis of mentioned experimental results. At the end these experimental and computed results are given. (Author)
Power distribution arrangement
DEFF Research Database (Denmark)
2010-01-01
An arrangement and a method for distributing power supplied by a power source to two or more of loads (e.g., electrical vehicular systems) is disclosed, where a representation of the power taken by a particular one of the loads from the source is measured. The measured representation of the amount...... of power taken from the source by the particular one of the loads is compared to a threshold to provide an overload signal in the event the representation exceeds the threshold. Control signals dependant on the occurring of the overload signal are provided such that the control signal decreases the output...... power of the power circuit in case the overload signal occurs...
Energy Technology Data Exchange (ETDEWEB)
Sorrells, M.A.
1990-01-01
This paper is a broad overview of industrial power distribution. Primary focus will be on selection of the various low voltage components to achieve the end product. Emphasis will be on the use of national standards to ensure a safe and well designed installation.
Intraocular lens power calculation in eyes with short axial length
Directory of Open Access Journals (Sweden)
Marilita M Moschos
2014-01-01
Full Text Available Aim: To evaluate and compare the predictive capacity of four intraocular lens (IOL power calculation formulas (SRK/T, Hoffer Q, Holladay 1, and Haigis in eyes shorter than 22.0 mm. Setting and Design: Observational study. Materials and Methods: Participants in our study were 69 consecutive patients with a preoperative axial length (AL of less than 22.0 mm in one or both eyes. All patients underwent phacoemulsification with IOL implantation and postoperative target of refraction was analyzed. Specifically, the differences in the mean absolute estimation error (AE for the four formulas were analyzed. Furthermore, the percentage of eyes with AE within ±0.5 and ±1.0 D for each formula was estimated, as well as the correlation coefficient (r between the AL and estimation error (E for each formula. The Mann-Whitney U test was used to compare differences in the AEs of the formulas. A statistically significant difference was defined as P < 0.05. Results: The Haigis formula had statistically significant smaller mean AE in comparison to Holladay 1, Hoffer Q, and SRK/T. The Haigis formula predicted more eyes with E within ±0.5 and ±1.0 D of predicted spherical equivalent compared to other formulas. Correlation between AL and AE revealed a negative r value and P < 0.05 for all formulas. Conclusions: Haigis formula provides more accurate results concerning the postoperative target of refraction in eyes with AL less than 22.0 mm. Hoffer Q could be also used as an alternative.
Electric power distribution reliability
Brown, Richard E
2002-01-01
Balancing theory, practical knowledge, and real-world applications, this reference consolidates all pertinent topics related to power distribution reliability into one comprehensive volume. Exploring pressing issues in creating and analyzing reliability models, the author highlights the most effective techniques to achieve maximum performance at lowest cost. With over 300 tables, figures, and equations, the book discusses service interruptions caused by equipment malfunction, animals, trees, severe weather, natural disasters, and human error and evaluates strategies to improve reliability and
Torki, Mohammad Ebrahim; Kazemi, Mohammad Taghi; Reddy, Junuthula N.; Haddadpoud, Hassan; Mahmoudkhani, Saeid
2014-02-01
In this paper, flutter of functionally graded material (FGM) cylindrical shells under distributed axial follower forces is addressed. The first-order shear deformation theory is used to model the shell, and the material properties are assumed to be graded in the thickness direction according to a power law distribution using the properties of two base material phases. The solution is obtained by using the extended Galerkin's method, which accounts for the natural boundary conditions that are not satisfied by the assumed displacement functions. The effect of changing the concentrated (Beck's) follower force into the uniform (Leipholz's) and linear (Hauger's) distributed follower loads on the critical circumferential mode number and the minimum flutter load is investigated. As expected, the flutter load increases as the follower force changes from the so-called Beck's load into the so-called Leipholz's and Hauger's loadings. The increased flutter load was calculated for homogeneous shell with different mechanical properties, and it was found that the difference in elasticity moduli bears the most significant effect on the flutter load increase in short, thick shells. Also, for an FGM shell, the increase in the flutter load was calculated directly, and it was found that it can be derived from the simple power law when the corresponding increase for the two base phases are known.
Addressing the Axial Burnup Distribution in PWR Burnup Credit Criticality Safety
International Nuclear Information System (INIS)
This paper summarizes efforts related to developing a technically justifiable approach for addressing the axial burnup distribution in PWR burnup-credit criticality safety analyses. The paper reviews available data on the axial variation in burnup and the effect of axial burnup profiles on reactivity in a SNF cask. A publicly available database of profiles is examined to identify profiles that maximize the neutron multiplication factor, keff, assess its adequacy for general PWR burnup credit analyses, and investigate the existence of trends with fuel type and/or reactor operations. For this assessment, a statistical evaluation of the keff values associated with the profiles in the axial burnup profile database was performed that identifies the most reactive profiles as statistical outliers that are not representative of typical discharged SNF assemblies. The impact of these bounding profiles on the neutron multiplication factor for a high-density burnup credit cask is quantified. Finally, analyses are presented to quantify the potential reactivity consequence of assemblies with axial profiles that are not bounded by the existing database. The paper concludes with findings for addressing the axial burnup distribution in burnup credit analyses
End effect analysis with various axial burnup distributions in high density spent fuel storage racks
International Nuclear Information System (INIS)
Highlights: • Criticality tests are carried out with various axial burnup distributions of fuel assemblies for spent fuel storage racks. • KENO-Va code system was used to obtain criticalities with 10 axial segments. • ORIGEN-S code system was used to obtain burnup dependent axial compositions. • The criticality and burnup dependent reactivity difference are obtained from the results. • End effect quantifications are satisfactory confirming the previous suggestions. - Abstract: End effect of spent fuel comes from the difference between uniform and actual axial burnup distributions of fuel assemblies. It is significant to control the criticality safety in spent fuel storage and transportation. This work is focused on estimation of end effect in the spent fuel of light water reactor for the spent fuel storage rack region-II. High and low burnups of corresponding different uranium enrichments are taken into consideration to analyze the end effect with different axial burnup distributions such as uniform, MOC and EOC profiles. Two types of fuel assemblies such as CE type and Westinghouse type are considered. The whole calculations have been carried out by using the SCALE6 code including ORIGEN-S and KENO-Va
Flow induced noise calculations for non-axially distributed hydrophones in towed arrays
Institute of Scientific and Technical Information of China (English)
WANG Bin; TANG Weilin; FAN Jun
2009-01-01
Two improvements are put forward on the analyses of flow induced noise in towed arrays. First, the differences between Corcos/Carpenter pressure fluctuation models have been discussed at length, as well as flow induced noise calculated with these two models. Second, flow induced noise received by the finite hydrophones distributed non-axially is discussed and the relevant power spectrum is deduced. The results show that there are some disparities between the wavenumber spectrums and the responses of flow induced noise of these two models. Flow induced noise is closely related with the tow speed, the tube radius and the off-axis distance. The numerical analyses with Carpenter model indicate that the power spectrum of flow induced noise will increase 24 dB approximately with the tow speed doubled, decrease with the radius of the tube, and increase with the off-axis distance. The tube radius and the off-axis distance have greater influence on the high-frequency components than on the low-frequency components.
Energy loss distributions of 7 TeV protons axially channeled in the bent Si crystal
Stojanov, Nace; Petrović, Srdjan
2016-04-01
In this article, the energy loss distributions of relativistic protons axially channeled in the bent Si crystal are studied. The crystal thickness is equal to 1 mm, which corresponds to the reduced crystal thickness, Λ, equal to 1.22, whereas the bending angle, α, was varied from 0 to 30 μrad. The proton energy of 7 TeV was chosen in accordance with the concept of using the bent crystals as a tool for selective deflection of the beam halo particles from the LUA9 experiment at LHC. For the continuum interaction potential of the proton and the crystal the Molière's expression was used and the energy loss of a proton was calculated by applying the trajectory dependent stopping power model. Further, the uncertainness of the scattering angle of the proton caused by its collisions with the electrons of the crystal and the divergence of the proton beam were taken into account. The energy loss distribution of the channeled protons was obtained via the numerical solution of the proton equations of motion in the transverse plane and the computer simulation method. The analysis of the obtained theoretical data shows that the shape of the energy loss distribution strongly depends on the horizontal or vertical direction of the curvature of the crystal. The number of dechanneled protons as a function of the bending angle also strongly depends on the direction of the crystal's curvature. As a result, the dechanneling rates and ranges, obtained from the Gompertz type sigmoidal fitting functions, have different sets of values for different bending orientations. We have also studied the influence of the proton beam divergence on the energy loss distribution of channeled protons.
Sensitivity studies for 3-D rod ejection analyses on axial power shape
Energy Technology Data Exchange (ETDEWEB)
Park, Min-Ho; Park, Jin-Woo; Park, Guen-Tae; Ryu, Seok-Hee; Um, Kil-Sup; Lee, Jae-Il [KEPCO NF, Daejeon (Korea, Republic of)
2015-10-15
The current safety analysis methodology using the point kinetics model combined with numerous conservative assumptions result in unrealistic prediction of the transient behavior wasting huge margin for safety analyses while the safety regulation criteria for the reactivity initiated accident are going strict. To deal with this, KNF is developing a 3-D rod ejection analysis methodology using the multi-dimensional code coupling system CHASER. The CHASER system couples three-dimensional core neutron kinetics code ASTRA, sub-channel analysis code THALES, and fuel performance analysis code FROST using message passing interface (MPI). A sensitivity study for 3-D rod ejection analysis on axial power shape (APS) is carried out to survey the tendency of safety parameters by power distributions and to build up a realistic safety analysis methodology while maintaining conservatism. The currently developing 3-D rod ejection analysis methodology using the multi-dimensional core transient analysis code system, CHASER was shown to reasonably reflect the conservative assumptions by tuning up kinetic parameters.
Three-dimensional integral imaging display system via off-axially distributed image sensing
Piao, Yongri; Qu, Hongjia; Zhang, Miao; Cho, Myungjin
2016-10-01
In this paper, we propose a three-dimensional integral imaging display system with a multiple recorded images using off-axially distributed image sensing. First, the depth map of the 3D objects is extracted from the off-axially recorded multi-perspective 2D images by using profilometry technique. Then, the elemental image array is computationally synthesized using the extracted depth map based on ray mapping model. Finally, the 3D images are optically displayed in integral imaging system. To show the feasibility of the proposed method, the optical experiments for 3D objects are carried out and presented in this paper.
Axial ion charge state distribution in the vacuum arc plasma jet
International Nuclear Information System (INIS)
We report on our experimental studies of the ion charge state distribution (CSD) of vacuum arc plasmas using a time-of-flight diagnostic method. The dependence of the CSD on the axial distance from the plasma source region was measured for a titanium vacuum arc. It was found that the axial CSD profile is nonuniform. Generally, the mean charge state increases approximately linearly with axial distance from about 1.7 at 12 cm up to 1.9 at 25 cm from the plasma source. A model for ion transport in the free boundary plasma jet is proposed which is based on the existence of an electric field in the quasineutral plasma. This model qualitatively explains the experimental results. (c) 2000 American Institute of Physics
Vibrational power flow of a finite cylindrical shell with discrete axial stiffeners
Institute of Scientific and Technical Information of China (English)
LIU Yanmei; HUANG Xieqing
2002-01-01
The structural wave power flows in an elastic finite cylindrical shell with discrete axial stiffeners are studied when a simple harmonic force is applied on it. The equations of motion of the shell are derived by using Flugge equation and Hamilton variational principle,and the responses of the shell are obtained. By use of the basic definition of the power flow, the characteristics of axial propagation of the power flow supplied by input structure and carried by different shell internal forces of a forced shell are investigated. The effects of parameters, such as relative location of driving force and stringer, driving force type and structural damping on the vibrational power flows in the shell, are discussed. These provide some theoretical bases for vibration control and noise reduction of this kind of structure.
Distribution of Cathode Spots in Vacuum Arc Under Nonuniform Axial Magnetic Fields
Institute of Scientific and Technical Information of China (English)
SHI Zong-qian; JIA Shen-li; WANG Li-jun; LI Xing-wen; WANG Zheng
2007-01-01
Recent results on the distribution of vacuum arc cathode spots (CSs) in nonuniform axial magnetic field (AMF) are presented.Based on previous studies,we deem that two contrary influences of AMF,inward effect and outward effect,are attributed to CSs distribution.With this notion,we have analyzed the controlling effectiveness of nonuniform AMF on CSs distribution. Experiments were conducted in a detachable vacuum chamber with iron-style AMF electrodes.Images of vacuum arc column and the distribution of CSs were photographed with a high-speed charge coupled device (CCD) camera. Experimental results agreed well with the theoretical analysis.
Optimal axial enrichment distribution of the boiling water reactor fuel under the Haling strategy
International Nuclear Information System (INIS)
The axial enrichment distribution of boiling water reactor fuel is optimized to improve uranium utilization subject to constraints on thermal margins. It is assumed that the reactor is operated under the Haling strategy, so that determination of the enrichment distribution can be decoupled from the poison management. This nonlinear optimization problem is solved using a method of approximation programming, where each iteration step is formulated in terms of linear goal programming to handle infeasible problems. The core is represented by an axial one-dimensional model. The average enrichment of a two-region fuel can be slightly reduced by increasing the enrichment of the lower half rather than the upper half. The optimal solutions for a 24-region fuel, in which the enrichments of indivdual nodes can differ from one another, display double-humped enrichment distributions. The natural uranium blanket design is also investigated, and it is concluded that blanketed fuel is practically optimal using the Haling strategy
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
Research on axial total pressure distributions of sonic steam jet in subcooled water
International Nuclear Information System (INIS)
The axial total pressure distributions of sonic steam jet in subcooled water were experimentally investigated for three different nozzle diameters (6.0 mm, 8.0 mm and 10.0 mm). The inlet steam pressure, and pool subcooling subcooled water temperature were in the range of 0.2-0.6 MPa and 420-860 ℃, respectively. The effect of steam pressure, subcooling water temperature and nozzle size on the axial pressure distributions were obtained, and also the characteristics of the maximum pressure and its position were studied. The results indicated that the characteristics of the maximum pressure were influenced by the nozzle size for low steam pressure, but the influence could be ignored for high steam pressure. Moreover, a correlation was given to correlate the position of the maximum pressure based on steam pressure and subcooling water temperature, and the discrepancies of predictions and experiments are within ±15%. (authors)
International Nuclear Information System (INIS)
The microscopic model for two-dimensional distribution function P(σ,η) for quadrupolar glass freezing of axial (σ) and eccentric (η) order parameters in solid hydrogen is considered within the Sherrington-Kirkpatrick mean-field approach. Assuming the exchange interactions between axial and eccentric quadrupoles to be independent Gaussian random variables with variance J2/N and K2/N, respectively (with N being the number of lattice sites), we derived a set of self-consistent equations for quadrupolar order parameters and the corresponding local susceptibilities. While for J≠K the axial quadrupolar order parameter is nonvanishing in the high-temperature phase due to broken local symmetry and the corresponding quadrupolar susceptibility exhibits smeared-out behavior, the eccentric order parameter becomes zero at well-defined critical temperature depending on the ratio K/J. Furthermore, the properties of the P(σ,η) distribution function are investigated by introducing a single effective order parameter σeff (1eff<0) directly related to the second frequency moment of the nuclear magnetic resonance line shapes. Comparison of the present microscopic theory with earlier phenomenological approaches to the problem is also made
Bending vibration of axially loaded Timoshenko beams with locally distributed Kelvin-Voigt damping
Chen, Wei-Ren
2011-06-01
Utilizing the Timoshenko beam theory and applying Hamilton's principle, the bending vibration equations of an axially loaded beam with locally distributed internal damping of the Kelvin-Voigt type are established. The partial differential equations of motion are then discretized into linear second-order ordinary differential equations based on a finite element method. A quadratic eigenvalue problem of a damped system is formed to determine the eigenfrequencies of the damped beams. The effects of the internal damping, sizes and locations of damped segment, axial load and restraint types on the damping and oscillating parts of the damped natural frequency are investigated. It is believed that the present study is valuable for better understanding the influence of various parameters of the damped beam on its vibration characteristics.
Energy Technology Data Exchange (ETDEWEB)
Chehab, A.G.; Moore, I.D. [Queen' s Univ., Kingston, ON (Canada). Dept. of Civil Engineering, Geoengineering Centre
2007-07-01
Underground pipes and utility lines can be installed using a a horizontal directional drilling (HDD) technique that makes use of a surface-monitored drilling rig that launches a drill string at shallow angle to the surface. The operation involves pilot bore excavation, back-reaming, and pullback. During the pullback operation, the pipe is subjected to loading from the drill string. It is also subjected to shear stresses between the outer surface of the pipe and the surrounding environment. These loads create complex axial stress distributions that vary along the pipe and with time. Since the axial stresses may influence the performance of the pipe, a one dimensional model was created to estimate tensile forces and stresses within pipes during pullback. The pipe was divided into elements, simulating the movement of the pulling head. Gravity forces, pipe-soil interaction forces and viscous drag forces applied on each element were then calculated based on its location along the borehole. The pipe-soil interaction used a simple model that considered adhesion, friction and soil stiffness. The elemental forces over the pipe length were integrated to estimate the axial force history along the pipe through the insertion process. The procedure was used to investigate the axial force distributions and cyclic response of pipes during pulling operations where the time history of movement of the pulling head was predetermined. The model accounted for nonlinear, time dependent polymer behaviour. It can be used to calculate the short and long term behaviour of high density polyethylene pipes during HDD installations. 10 refs., 1 tab., 10 figs.
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...
Hydrogen turbines for space power systems: A simplified axial flow gas turbine model
Hudson, Steven L.
1988-01-01
Hydrogen cooled, turbine powered space weapon systems require a relatively simple, but reasonably accurate hydrogen gas expansion turbine model. Such a simplified turbine model would require little computational time and allow incorporation into system level computer programs while providing reasonably accurate volume/mass estimates. This model would then allow optimization studies to be performed on multiparameter space power systems and provide improved turbine mass and size estimates for the various operating conditions (when compared to empirical and power law approaches). An axial flow gas expansion turbine model was developed for these reasons and is in use as a comparative bench mark in space power system studies at Sandia. The turbine model is based on fluid dynamic, thermodynamic, and material strength considerations, but is considered simplified because it does not account for design details such as boundary layer effects, shock waves, turbulence, stress concentrations, and seal leakage. Although the basic principles presented here apply to any gas or vapor axial flow turbine, hydrogen turbines are discussed because of their immense importance on space burst power platforms.
Microwave emission from an AXIAL-Virtual Cathode Oscillator driven by a compact pulsed power source
Shukla, R.; Sharma, S. K.; Banerjee, P.; Deb, P.; Prabaharan, T.; Das, R.; Kdas, B.; Adhikary, B.; Verma, R.; Shyam, A.
2012-11-01
For the generation of microwaves, Electron beam devices operating in vacuum are most widely used. For pulsed and high power microwave generation, Virtual cathode oscillators (VIRCATORs) are said to be simple in operation and construction. They are generally driven by a pulsed power source which gives high input powers to the Vircator connected as load. Vircator, depending upon its efficiency, converts the electrical input power to the microwave power. We are presenting the results of an axial Vircator operating in 2×10-4 mbar vacuum and is driven by a compact pulsed power source. The energy source and pulse compression is realized in very user friendly approach to run the system. The radiating system presently runs at relatively low powers but has the scope of reaching to high power by a logical improvement. A study of effect of collapsing diode impedance, of the vacuum field emission diode of the Vircator, on the microwave emission is presented in the paper. We are also presenting the microwave emission measurement conducted in the given system. Effect of vacuum is also studied to the extent of present experimental limits.
Microwave emission from an AXIAL-Virtual Cathode Oscillator driven by a compact pulsed power source
International Nuclear Information System (INIS)
For the generation of microwaves, Electron beam devices operating in vacuum are most widely used. For pulsed and high power microwave generation, Virtual cathode oscillators (VIRCATORs) are said to be simple in operation and construction. They are generally driven by a pulsed power source which gives high input powers to the Vircator connected as load. Vircator, depending upon its efficiency, converts the electrical input power to the microwave power. We are presenting the results of an axial Vircator operating in 2×10−4 mbar vacuum and is driven by a compact pulsed power source. The energy source and pulse compression is realized in very user friendly approach to run the system. The radiating system presently runs at relatively low powers but has the scope of reaching to high power by a logical improvement. A study of effect of collapsing diode impedance, of the vacuum field emission diode of the Vircator, on the microwave emission is presented in the paper. We are also presenting the microwave emission measurement conducted in the given system. Effect of vacuum is also studied to the extent of present experimental limits.
Energy Technology Data Exchange (ETDEWEB)
Bhoi, P.R. [Department of Mechanical Engineering, L and T-Sargent and Lundy Limited, L and T Energy Centre, Near Chhani Jakat Naka, Baroda 390 002 (India); Channiwala, S.A. [Department of Mechanical Engineering, Sardar Vallabhbhai National Institute of Technology, Deemed University, Ichchhanath, Surat 395 007, Gujarat (India)
2009-03-15
This paper presents the emission characteristics and axial flame temperature distribution of producer gas fired premixed burner. The producer gas fired premixed burner of 150 kW capacity was tested on open core throat less down draft gasifier system in the present study. A stable and uniform flame was observed with this burner. An instrumented test set up was developed to evaluate the performance of the burner. The conventional bluff body having blockage ratio of 0.65 was used for flame stabilization. With respect to maximum flame temperature, minimum pressure drop and minimum emissions, a swirl angle of 60 seems to be optimal. The experimental results also showed that the NO{sub x} emissions are inversely proportional to swirl angle and CO emissions are independent of swirl angle. The minimum emission levels of CO and NO{sub x} are observed to be 0.167% and 384 ppm respectively at the swirl angle of 45-60 . The experimental results showed that the maximum axial flame temperature distribution was achieved at A/F ratio of 1.0. The adiabatic flame temperature of 1653 C was calculated theoretically at A/F ratio of 1.0. Experimental results are in tune with theoretical results. It was also concluded that the CO and UHC emissions decreases with increasing A/F ratio while NO{sub x} emissions decreases on either side of A/F ratio of 1.0. (author)
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
Contribution to the power distribution methodology uncertainties assessment
International Nuclear Information System (INIS)
The present methodology of safety margins in NPP Dukovany design power distribution calculations is based on the philosophy of engineering factors with errors defined on the bases of statistical approach of standard (95%) confidence intervals. On the level of FA power distribution the normality (normal density distribution) of this approach is tested and comparison with errors defined on the 95-percent probability at a 95-percent confidence level (shortly in statistics 95%/95%)) is provided. Practical applications are presented for several NPP Dukovany fuel cycles. The paper also deals briefly with difference between confidence interval and tolerance interval, with the problems of density distribution of mechanical engineering factor variables and solution of axial and radial error distribution like bivariate problem. (Author)
On one model of stellar clusters with axial symmetry and discrete mass distribution of stars
International Nuclear Information System (INIS)
A model of a stationary stellar cluster with axial symmetry and with stellar composition, homogeneous by mass is generalized for the case of a model with stellar composition discretely distributed by mass. From the solution obtained it follows that the summary mass density of stars D, statistic P and dynamic Q of pressure as well as mean circular velocity of stars Vo concide in the both models. However in the second model density distributions of a number of stars nsub(i) (i = 1,2..., k) are different for stellar groups various by mass and do not coincide with a summary density distribution of mass of a star. The latter result gives a possibility to explain a disk structure of SO-galaxies as a Unification of a great number of ring distributions of mean and light stars. Besides that this result allows to explain a bright ring structure, observed in some SO-galaxies, as a prevalence in a general disk structure of one numerous group of mean by mass stars with ring distribution. It is shown also that with some values of parameters a ring structure can form in bipolar clusters
Kr II and Xe II axial velocity distribution functions in a cross-field ion source
International Nuclear Information System (INIS)
Laser induced fluorescence measurements were carried out in a cross-field ion source to examine the behaviour of the axial ion velocity distribution functions (VDFs) in the expanding plasma. In the present paper, we focus on the axial VDFs of Kr II and Xe II ions. We examine the contourplots in a 1D-phase space (x,vx) representation in front of the exhaust channel and along the centerline of the ion source. The main ion beam, whose momentum corresponds to the ions that are accelerated through the whole potential drop, is observed. A secondary structure reveals the ions coming from the opposite side of the channel. We show that the formation of the neutralized ion flow is governed by the annular geometry. The assumption of a collisionless shock or a double layer due to supersonic beam interaction is not necessary. A non-negligible fraction of slow ions originates in local ionization or charge-exchange collision events between ions of the expanding plasma and atoms of the background residual gas. Slow ions that are produced near the centerline in the vicinity of the exit plane are accelerated toward the source body with a negative velocity leading to a high sputtering of front face. On the contrary, the ions that are produced in the vicinity of the channel exit plane are partially accelerated by the extended electric field.
Directory of Open Access Journals (Sweden)
Anita
2016-02-01
Full Text Available PURPOSE To compare the accuracy of Intraocular Lens (IOL power calculation formulae in high axial myopia. MATERIAL AND METHODS 27 eyes of 22 patients with axial length between 26mm to 30mm were studied. The eyes were divided in to two groups, Group 1 with AL 26-28mm consisting of 23 eyes and Group 2 with AL 28-30mm consisting of four eyes. The predictive accuracy of four formulae SRK-T, Hoffer Q, Haigis and Holladay 2 were evaluated and compared. The statistical analysis was carried out with SPSS Software 21.0 version with P value >0.05 considered significant. RESULTS The predictive capability within ±1 D of these formulae in Group 1 is 88% with SRK-T, 87% with Hoffer Q, 88% with Haigis and 91% with Holladay 2 and within ±0.5 D is 61%, 61%, 69% and 73% respectively. In Group 2 which consisted of 4 eyes with AL between 28-30mm the results were 83%, 83%, 84%, 90%, 59%, 61%, 70%, 71% respectively. CONCLUSION The performance of SRK-T, Hoffer Q and Haigis was comparable for target refraction of ±1.0 D, whereas Haigis and Holladay 2 gave relatively better results for target refraction of ±0.5 D for Group 1 and Haigis and Holladay 2 performed better for Group 2.
Prediction of heater power distribution in radiative cylindrical furnaces
Energy Technology Data Exchange (ETDEWEB)
Ravichandran, M.; Dilber, I.; Torok, D.
1999-07-01
In the design of long radiative cylindrical furnaces, it is important to control the temperature variation along the furnace walls and consequently the temperature distribution in the processed material by selectively adjusting the power input to heater rods located circumferentially around the furnace walls. The heaters are grouped in zones located at different axial locations. By adjusting the power to each zone a specified temperature distribution along the furnace can be attained. The radiative interchange between different axial zones of the furnace affects the temperature distribution; this interchange is also impacted by the shadowing caused by the presence of the load, i.e. the processed material. A desired temperature distribution can only be achieved by selectively changing the power input to the heaters. For an a priori assessment of the commercial viability of using process friendly temperature distributions, it is necessary to determine: (a) the maximum power demand from each zone; (b) if active cooling is inevitable and (c) the bounds on temperature distribution that can be achieved without active cooling. It is therefore extremely useful to be able to predict the input power distribution for achieving desired furnace temperature profiles. For a given power input, the temperature distribution inside the furnace could be obtained by using a general purpose Computational Fluid Dynamics (CFD) software, such as FIDAP. A new methodology is developed within the framework of FIDAP software to eliminate the manual trial and error method. The method is based on obtaining the sensitivity of the temperature at the desired locations of the furnace as a function of the power input to the heating elements. Using these sensitivity coefficients, an iterative scheme is designed to adjust the boundary conditions (power to the heating elements in this case) based on the discrepancy of the solution temperatures from the desired temperature distribution. For each of these
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)
Development of an Axial Flux MEMS BLDC Micromotor with Increased Efficiency and Power Density
Directory of Open Access Journals (Sweden)
Xiaofeng Ding
2015-06-01
Full Text Available This paper presents a rigorous design and optimization of an axial flux microelectromechanical systems (MEMS brushless dc (BLDC micromotor with dual rotor improving both efficiency and power density with an external diameter of only around 10 mm. The stator is made of two layers of windings by MEMS technology. The rotor is developed by film permanent magnets assembled over the rotor yoke. The characteristics of the MEMS micromotor are analyzed and modeled through a 3-D magnetic equivalent circuit (MEC taking the leakage flux and fringing effect into account. Such a model yields a relatively accurate prediction of the flux in the air gap, back electromotive force (EMF and electromagnetic torque, whilst being computationally efficient. Based on 3-D MEC model the multi-objective firefly algorithm (MOFA is developed for the optimal design of this special machine. Both 3-D finite element (FE simulation and experiments are employed to validate the MEC model and MOFA optimization design.
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...
Elastic Plastic Stress Distributions in Weld-bonded Lap Joint under Axial Loading
Directory of Open Access Journals (Sweden)
Essam A. Al-Bahkali
2014-06-01
Full Text Available Weld-bonding process is increasingly used in many industries such like automobile and aerospace. It offers significant improvements of sheet metal joints in static, dynamic, corrosion, noise resistance, stiffness and impact toughness properties. A full understanding of this process, including the elastic-plastic stress distribution in the joint, is a must for joints design and automation of manufacturing. Also, the modelling and analysis of this process, though it is complex, proves to be of prime importance. Thus, in this study a systematic experimental and theoretical study employing Finite Element Analysis (FEA is conducted on the weld-bonded joint, fabricated from Austenitic Stainless steel (AISI 304 sheets of 1.00 mm thickness and Epoxy adhesive Araldite 2011, subjected to axial loading. Complete 3-D finite element models are developed to evaluate the normal, shear and triaxial Von Mises stresses distributions across the entire joint, in both the elastic and plastic regions. The, needed quantities and properties, for the FE modelling and analysis, of the base metals and the adhesive, such like the elastic-plastic properties, modulus of elasticity, fracture limit, the nugget and Heat Affected Zones (HAZ properties, etc., are obtained from the experiments. The stress distribution curves obtained are found to be consistent with those obtained from the FE models and in excellent agreement with the experimental and theoretical published data, particularly in the elastic region. Furthermore, the stress distribution curves obtained for the weld-bonded joint display the best uniform smooth distribution curves compared to those obtained for the spot and bonded joint cases. The stress concentration peaks at the edges of the weld-bonded region, are almost eliminated resulting in achieving the strongest joint.
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
Directory of Open Access Journals (Sweden)
Stephen Whaite
2015-05-01
Full Text Available This review paper discusses power quality considerations for direct current (DC electric power distribution systems, particularly DC microgrids. First, four selected sample DC architectures are discussed to provide motivation for the consideration of power quality in DC systems. Second, a brief overview of power quality challenges in conventional alternating current (AC distribution systems is given to establish the field of power quality. Finally, a survey of literature addressing power quality issues in DC systems is presented, and necessary power quality considerations in DC distribution system design and operation are discussed.
Energy loss distributions of relativistic protons axially channeled in a bent silicon crystal
Stojanov, Nace; Petrović, Srdjan; Nešković, Nebojša
2013-05-01
A detailed study of the energy loss distributions of the relativistic protons axially channeled in the bent 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.
Energy loss distributions of relativistic protons axially channeled in a bent silicon crystal
Energy Technology Data Exchange (ETDEWEB)
Stojanov, Nace, E-mail: nacestoj@pmf.ukim.mk [Institute of Physics, Faculty of Natural Sciences and Mathematics, Sts. Cyril and Methodius University, P.O. Box 162, 1000 Skopje (Macedonia, The Former Yugoslav Republic of); Petrović, Srdjan; Nešković, Nebojša [Laboratory of Physics (010), Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia)
2013-05-01
A detailed study of the energy loss distributions of the relativistic protons axially channeled in the bent < 100 > Si crystals is presented in this work. The bending angle was varied from 0 to 20 μrad, while the crystal thickness was equal to 1 mm. The proton energy was chosen to be 7 TeV in accordance with the Large Hadron Collider (LHC) project, at the European Organization for Nuclear Research (CERN), in Geneva, Switzerland. The energy loss distributions of the channeled protons were generated using the numerical solution of the proton equations of motion in the transverse plane and the computer simulation method. An accurate energy loss model was used, which takes into account the trajectory dependence of the energy loss of protons during their motion through the crystal channels. Further, the dispersion of the proton’s scattering angle caused by its collisions with the electrons of the crystal and the divergence of the proton beam were taken into account. The calculated dependence of the number of dechanneled protons on the bending angle was excellently fitted by the Gompertz type dechanneling function.
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.
Effects of axial power shapes on CHF locations in a single tube and in rod bundle assemblies
Energy Technology Data Exchange (ETDEWEB)
Han, B.; Yang, B.W.; Zhang, H.; Zha, Y.; Zhang, Y. [Xi' an Jiaotong Univ. (China). School of Nuclear Science and Technology
2016-07-15
Currently, the prediction of rod bundle CHF is dependent on CHF correlations derived from CHF data. A simple correction factor, such as F-factor, is often used to account for the axial power shape differences based on a simple accumulated energy concept, which has totally no consideration on the impact of true local condition on CHF mechanism. Subsequently, as expected, large uncertainty is often associated with the CHF value and CHF location predictions. For the purpose of obtaining different power shapes effects on CHF, CFD calculated parameter values were used to predict the possible CHF occurrence location. The possible CHF location prediction method proposed in this paper is calculated void fraction, heat transfer coefficient (HTC), liquid temperature distribution and detailed local parameters. And the uniform and non-uniform CHF were analyzed. The prediction of possible CHF locations in a 5 x 5 rod bundle may provide useful information for the design of a full-length CHF test, enhance the accuracy of CHF and CHF location prediction, and reduce the costs of the experimentation.
Wind Power in Electrical Distribution Systems
DEFF Research Database (Denmark)
Chen, Zhe
2013-01-01
Recent years, wind power is experiencing a rapid growth, large number of wind turbines/wind farms have been installed and connected to power systems. In addition to the large centralised wind farms connected to transmission grids, many distributed wind turbines and wind farms are operated...... as distributed generators in distribution systems. This paper discusses the issues of wind turbines in distribution systems. Wind power conversion systems briefly introduced, the basic features and technical characteristics of distributed wind power system are described, and the main technical demands...
Diffusion air effects on the soot axial distribution concentration in a premixed acetylene/air flame
Energy Technology Data Exchange (ETDEWEB)
Fassani, Fabio Luis; Santos, Alex Alisson Bandeira; Goldstein Junior, Leonardo [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Engenharia Termica e de Fluidos]. E-mails: fassani@fem.unicamp.br; absantos@fem.unicamp.br; leonardo@fem.unicamp.br; Ferrari, Carlos Alberto [Universidade Estadual de Campinas, SP (Brazil). Inst. de Fisica. Dept. de Eletronica Quantica]. E-mail: ferrari@ifi.unicamp.br
2000-07-01
Soot particles are produced during the high temperature pyrolysis or combustion of hydrocarbons. The emission of soot from a combustor, or from a flame, is determined by the competition between soot formation and its oxidation. Several factors affect these processes, including the type of fuel, the air-to-fuel ratio, flame temperature, pressure, and flow pattern. In this paper, the influence of the induced air diffusion on the soot axial distribution concentration in a premixed acetylene/air flame was studied. The flame was generated in a vertical axis burner in which the fuel - oxidant mixture flow was surrounded by a nitrogen discharge coming from the annular region between the burner tube and an external concentric tube. The nitrogen flow provided a shield that protected the flame from the diffusion of external air, enabling its control. The burner was mounted on a step-motor driven, vertical translation table. The use of several air-to-fuel ratios made possible to establish the sooting characteristics of this flame, by measuring soot concentration along the flame height with a non-intrusive laser light absorption technique. (author)
Distributed Generation and Resilience in Power Grids
Scala, Antonio; Chessa, Alessandro; Caldarelli, Guido; Damiano, Alfonso
2012-01-01
We study the effects of the allocation of distributed generation on the resilience of power grids. We find that an unconstrained allocation and growth of the distributed generation can drive a power grid beyond its design parameters. In order to overcome such a problem, we propose a topological algorithm derived from the field of Complex Networks to allocate distributed generation sources in an existing power grid.
Directory of Open Access Journals (Sweden)
Ryo Obata
Full Text Available PURPOSE: It has not been clarified whether early age-related macular degeneration (AMD is associated with cone photoreceptor distribution. We used adaptive optics fundus camera to examine cone photoreceptors in the macular area of aged patients and quantitatively analyzed its relationship between the presence of early AMD and cone distribution. METHODS: Sixty cases aged 50 or older were studied. The eyes were examined with funduscopy and spectral-domain optical coherence tomography to exclude the eyes with any abnormalities at two sites of measurement, 2° superior and 5° temporal to the fovea. High-resolution retinal images with cone photoreceptor mosaic were obtained with adaptive optics fundus camera (rtx1, Imagine Eyes, France. After adjusting for axial length, cone packing density was calculated and the relationship with age, axial length, or severity of early AMD based on the age-related eye disease study (AREDS classification was analyzed. RESULTS: Patient's age ranged from 50 to 77, and axial length from 21.7 to 27.5 mm. Mean density in metric units and that in angular units were 24,900 cells/mm2, 2,170 cells/deg2 at 2° superior, and 18,500 cells/mm2, 1,570 cels/deg2 at 5° temporal, respectively. Axial length was significantly correlated with the density calculated in metric units, but not with that in angular units. Age was significantly correlated with the density both in metric and angular units at 2° superior. There was no significant difference in the density in metric and angular units between the eyes with AREDS category one and those with categories two or three. CONCLUSION: Axial length and age were significantly correlated with parafoveal cone photoreceptor distribution. The results do not support that early AMD might influence cone photoreceptor density in the area without drusen or pigment abnormalities.
Converters for Distributed Power Generation Systems
DEFF Research Database (Denmark)
Blaabjerg, Frede; Yang, Yongheng
2015-01-01
presents an overview of the power converters for the DPGS, mainly based on wind turbine systems and photovoltaic systems, covering a wide range of applications. Moreover, the modulation schemes and interfacing power filters for the power converters are also exemplified. Finally, the general control......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...
Distributed systems for protecting nuclear power stations
International Nuclear Information System (INIS)
The advantages of distributed control systems for the control of nuclear power stations are obviously of great interest. Some years ago, EPRI, (Electric Power Research Institute) showed that multiplexing the signals is technically feasible, that it enables the availability specifications to be met and costs to be reduced. Since then, many distributed control systems have been proposed by the manufacturers. This note offers some comments on the application of the distribution concept to protection systems -what should be distributed- and ends with a brief description of a protection system based on microprocessors for the pressurized power stations now being built in France
Directory of Open Access Journals (Sweden)
W. F. Harris
2009-12-01
Full Text Available If an intraocular lens is displaced or if its power is changed what are the consequences for the refractive compensation of the eye? Gaussian optics is used to obtain explicit formulae for the sensitivityof the corneal-plane refractive compensation (also called the refraction, refractive state, etc to change in power and axial displacement of a thin intraocular lens implanted in a simple eye. In particular, for a pseudophakic Gullstrand simplified eye with intraocular lens placed 5 mm behind the cornea the sensitivity to errors in the power of the intraocular lens is about 71 . 0 − 71 for an intraocular lens of power for an intraocular lens of power 20 D, that is, the refractive compensation decreases by about 0.71 dioptres per dioptre increase in the power of the intraocular lens. More generally the sensitivity is approximately ( m 0037 . 0 63 . 0 F − − 0.63 ( 003 . 0 63 . 0 − − (0.0037mF where FI is the power of the intraocular lens. Also for Gullstrand’s simplified eye the sensitivity of refractive compensation to axial displacement of the intraocular lens is approximately linear in FI about (64D FI, in fact. That is, for each dioptre of the power of the intraocular lens the refractive compensation increases by about 0.064 dioptres per millimetre of axial displacement towards the retina.
Inhomogeneous Power Distribution in Magnetic Oscillations
Jain, Kiran; Kholikov, S; Hill, F
2010-01-01
We apply ring-diagram analysis and spherical harmonic decomposition methods to compute 3-dimensional power spectra of magnetograms obtained by the Global Oscillation Network Group (GONG) during quiet periods of solar activity. This allows us to investigate the power distribution in acoustic waves propagating in localized directions on the solar disk. We find evidence of the presence of five-minute oscillations in magnetic signals that suggests a non-homogeneous distribution of acoustic power. In this paper, we present our results on the asymmetry in oscillatory power and its behaviour as a function of frequency, time and magnetic field strength. These characteristics are compared with simultaneous velocity measurements.
Energy Technology Data Exchange (ETDEWEB)
Mayhall, D J; Stein, W; Gronberg, J B
2006-05-15
We have performed preliminary computer-based, transient, magnetostatic calculations of the eddy-current power loss in rotating titanium-alloy and aluminum wheels and wheel rims in the predominantly axially-directed, steady magnetic fields of two small, solenoidal coils. These calculations have been undertaken to assess the eddy-current power loss in various possible International Linear Collider (ILC) positron target wheels. They have also been done to validate the simulation code module against known results published in the literature. The commercially available software package used in these calculations is the Maxwell 3D, Version 10, Transient Module from the Ansoft Corporation.
Power Electronics Control of Wind Energy in Distributed Power System
DEFF Research Database (Denmark)
Iov, Florin; Ciobotaru, Mihai; Blaabjerg, Frede
2008-01-01
is to change the electrical power production sources from the conventional, fossil (and short term) based energy sources to renewable energy resources. The other is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss the most...... emerging renewable energy sources, wind energy, which by means of power electronics are changing from being a minor energy source to be acting as an important power source in the energy system. Power electronics is the enabling technology and the presentation will cover the development in wind turbine...... technology from kW to MW, discuss which power electronic solutions are most feasible and used today....
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.
Power Quality Improvement of a Distributed Generation Power System
Directory of Open Access Journals (Sweden)
Panga Harish
2016-06-01
Full Text Available The aim of this work is to improve the power quality for Distributed Generation (DG with power storage system. Power quality is the combination of voltage quality and current quality. Power quality is the set of limits of electrical properties that allows electrical systems to function in their intended manner without significant loss of performance or life. The electrical power quality is more concerned issue. The main problems are stationery and transient distortions in the line voltage such as harmonics, flicker, swells, sags and voltage asymmetries. Distributed Generation (DG also called as site generation, dispersed generation, embedded generation, decentralized generation, decentralized energy or distributed energy, generates electricity from the many small energy sources. In recent years, micro electric power systems such as photovoltaic generation systems, wind generators and micro gas turbines, etc., have increased with the deregulation and liberalization of the power market. Under such circumstances the environment surrounding the electric power industry has become ever more complicated and provides high-quality power in a stable manner which becomes an important topic. Here DG is assumed to include Wind power Generation (WG and Fuel Cells (FC, etc. Advantages of this system are constant power supply, constant voltage magnitude, absence of harmonics insupply voltage, un-interrupted power supply. In this project the electric power qualities in two cases will be compared. Case I: With the storage battery when it is introduced. Case II: Without the storage battery. The storage battery executes the control that maintains the voltage in the power system. It will be found that the Electric power quality will be improved, when storage battery is introduced. The model system used in this Project work is composed of a Wind Turbine, an Induction Generator, Fuel Cells, An Inverter and a Storage Battery. A miniature Wind Power Generator is
Distributed generation and centralized power system in Thailand
DEFF Research Database (Denmark)
Sukkumnoed, Decharut
The paper examines and discusses conflicts between the development of distributed power and centralized power system in Thailand.......The paper examines and discusses conflicts between the development of distributed power and centralized power system in Thailand....
Power distribution studies for CMS forward tracker
International Nuclear Information System (INIS)
The Electronic Systems Engineering Department of the Computing Division at the Fermi National Accelerator Laboratory is carrying out R and D investigations for the upgrade of the power distribution system of the Compact Muon Solenoid (CMS) Pixel Tracker at the Large Hadron Collider (LHC). Among the goals of this effort is that of analyzing the feasibility of alternative powering schemes for the forward tracker, including DC to DC voltage conversion techniques using commercially available and custom switching regulator circuits. Tests of these approaches are performed using the PSI46 pixel readout chip currently in use at the CMS Tracker. Performance measures of the detector electronics will include pixel noise and threshold dispersion results. Issues related to susceptibility to switching noise will be studied and presented. In this paper, we describe the current power distribution network of the CMS Tracker, study the implications of the proposed upgrade with DC-DC converters powering scheme and perform noise susceptibility analysis.
Reliability assessment of distribution power systems including distributed generations
International Nuclear Information System (INIS)
Nowadays, power systems have reached a good level of reliability. Nevertheless, considering the modifications induced by the connections of small independent producers to distribution networks, there's a need to assess the reliability of these new systems. Distribution networks present several functional characteristics, highlighted by the qualitative study of the failures, as dispersed loads at several places, variable topology and some electrotechnical phenomena which must be taken into account to model the events that can occur. The adopted reliability calculations method is Monte Carlo simulations, the probabilistic method most powerful and most flexible to model complex operating of the distribution system. We devoted a first part on the case of a 20 kV feeder to which a cogeneration unit is connected. The method was applied to a software of stochastic Petri nets simulations. Then a second part related to the study of a low voltage power system supplied by dispersed generations. Here, the complexity of the events required to code the method in an environment of programming allowing the use of power system calculations (load flow, short-circuit, load shedding, management of units powers) in order to analyse the system state for each new event. (author)
Rehme, K.
1987-03-01
The velocity, turbulence, and temperature distributions in nuclear fuel element bundles of nuclear reactors were investigated. The mean velocity, the wall shear stresses, and the turbulence were measured in two wall subchannels of a rod bundle of four parallel rods, arranged in a rectangular channel, for three axial planes. A spacer grid was inserted in the rod bundle, for ratios between the distance spacer grid/measuring plane and the hydraulic diameter (LIDh) of 40.4, 32.8 and 16.9. The Reynolds number was 145,000. The results show that the distributions of the velocity and the turbulence are affected by the spacer grid, already for LIDh = 40.4. The effects of the spacer grid increase with decreasing distance to the spacer grid.
Optimal Distributed Voltage Regulation in Power Distribution Networks
Lam, Albert Y S; Dominguez-Garcia, Alejandro; Tse, David
2012-01-01
In this paper, we address the problem of voltage regulation in power distribution networks with deep-penetration of distributed energy resources (DERs), e.g., renewable-based generation, and storage-capable loads such as plug-in hybrid electric vehicles. We cast the problem as an optimization program, where the objective is to minimize the losses in the network subject to constraints on bus voltage magnitudes, limits on active and reactive power injections, transmission line thermal limits and losses. We provide sufficient conditions under which the optimization problem can be solved via its convex relaxation. Using data from existing networks, we show that the conditions are expected to be satisfied by most networks. We also provide an efficient distributed algorithm to solve the problem. The algorithm is asynchronous, with a communication topology that is the same as the electrical network topology. We illustrate the algorithm's performance in the IEEE 34-bus and the 123-bus feeder test systems.
Power quality in electric distribution systems
International Nuclear Information System (INIS)
the power quality of the electric system is defined by the constant values of the voltage and frequency, the good value of the power factor close to unity, and balanced three phase voltages and currents. capacitors are widely installed in distribution systems for reactive power compensation to achieve power and energy loss reduction, voltage regulation and system capacity release. the extent of these benefits depends greatly on low the capacitors are placed on the system . the problem of how to place capacitors on the system such that these benefits are achieved and / or maximized against the cost associated with the capacitor placement is termed the general capacitor placement problem.the presented mathematical model has been developed to determine the size, number, and location of fixed capacitor banks that will maximize the saving derived from reduction in peak power and energy loss, and that will minimize the capital and installation costs of capacitors
DC-DC switching converter based power distribution vs serial power distribution EMC strategies
Arteche, F; Iglesias, M; Rivetta, C; Arcega, F G; Vila, I
2009-01-01
This paper presents a detailed and comparative analysis from the electromagnetic compatibility point of view of the proposed power distributions for the SLHC tracker up-grade. The main idea is to identify and quantify the noise sources, noise distribution at the system level and the sensitive areas in the front-end electronics corresponding to both proposed topologies: The DC-DC converter based power distribution and the serial power distribution. These studies will be used to define critical points on both systems to be studied and prototyped to ensure the correct integration of the system taking critically into account the electromagnetic compatibility. This analysis at the system level is crucial to ensure the final performance of the detector using non conventional power distributions, avoiding interference problems and excessive losses that can lead to catastrophic failures or expensive and un-practical solutions.
Improvement of power quality using distributed generation
Energy Technology Data Exchange (ETDEWEB)
Moreno-Munoz, A.; Lopez-Rodriguez, M.A.; Flores-Arias, J.M.; Bellido-Outerino, F.J. [Universidad de Cordoba, Departamento A.C., Electronica y T.E., Escuela Politecnica Superior, Campus de Rabanales, E-14071 Cordoba (Spain); de-la-Rosa, J.J.G. [Universidad de Cadiz, Area de Electronica, Dpto. ISA, TE y Electronica, Escuela Politecnica Superior Avda, Ramon Puyol, S/N, E-11202-Algeciras-Cadiz (Spain); Ruiz-de-Adana, M. [Universidad de Cordoba, Departamento de Quimica Fisica y Termodinamica Aplicada, Campus de Rabanales, E-14071 Cordoba (Spain)
2010-12-15
This paper addresses how Distributed Generation (DG), particularly when configured in Combined Heat and Power (CHP) mode, can become a powerful reliability solution in highlight automated factories, especially when integrated with complimentary Power Quality (PQ) measures. The paper presents results from the PQ audit conducted at a highly automated plant over last year. It was found that the main problems for the equipment installed were voltage sags. Among all categories of electrical disturbances, the voltage sag (dip) and momentary interruption are the nemeses of the automated industrial process. The paper analyzes the capabilities of modern electronic power supplies and the convenience of embedded solution. Finally it is addressed the role of the DG/CHP on the reliability of digital factories. (author)
Intelligent distributed control for nuclear power plants
Energy Technology Data Exchange (ETDEWEB)
Klevans, E.H.; Edwards, R.M.; Ray, A.; Lee, K.Y.; Garcia, H.E.: Chavez, C.M.; Turso, J.A.; BenAbdennour, A.
1991-01-01
In September of 1989 work began on the DOE University Program grant DE-FG07-89ER12889. The grant provides support for a three year project to develop and demonstrate Intelligent Distributed Control (IDC) for Nuclear Power Plants. The body of this Second Annual Technical Progress report covers the period from September 1990 to September 1991. It summarizes the second year accomplishments while the appendices provide detailed information presented at conference meetings. These are two primary goals of this research. The first is to combine diagnostics and control to achieve a highly automated power plant as described by M.A. Schultz, a project consultant during the first year of the project. This philosophy, as presented in the first annual technical progress report, is to improve public perception of the safety of nuclear power plants by incorporating a high degree automation where greatly simplified operator control console minimizes the possibility of human error in power plant operations. A hierarchically distributed control system with automated responses to plant upset conditions is the focus of our research to achieve this goal. The second goal is to apply this research to develop a prototype demonstration on an actual power plant system, the EBR-II steam plant.
Energy Technology Data Exchange (ETDEWEB)
Yao, Shengjie; Sun, Lei; Ma, Xudong [Harbin Institute of Technology, Weihai (China)
2016-05-15
This paper presents the deformation behavior and crash worthiness of electric resistance welded mild steel tubes with axial gradient microstructures in quasi-static compression. Three sets of tubes were prepared, and regions of each tube were Induction heated and directly quenched (IH-DQ). The effect of the length to diameter (L/D) ratio, and length of the IH-DQ region on crushing characteristics was investigated, and compared with untreated tubes. The compression tests revealed that improved energy absorption can be obtained in IHDQ tubes if the collapse is controlled by the formation of a concertina buckling mode. However, there was a tendency to produce mixed or Euler buckling modes as the ratio of L/D increased. Meanwhile, the results of the crush experiments and the FEM models showed that the heat-treatment process should be precisely controlled to produce the correct type of microstructure, and circumferential uniformity of microstructure distribution.
Optimal power flow for distribution networks with distributed generation
Directory of Open Access Journals (Sweden)
Radosavljević Jordan
2015-01-01
Full Text Available This paper presents a genetic algorithm (GA based approach for the solution of the optimal power flow (OPF in distribution networks with distributed generation (DG units, including fuel cells, micro turbines, diesel generators, photovoltaic systems and wind turbines. The OPF is formulated as a nonlinear multi-objective optimization problem with equality and inequality constraints. Due to the stochastic nature of energy produced from renewable sources, i.e. wind turbines and photovoltaic systems, as well as load uncertainties, a probabilisticalgorithm is introduced in the OPF analysis. The Weibull and normal distributions are employed to model the input random variables, namely the wind speed, solar irradiance and load power. The 2m+1 point estimate method and the Gram Charlier expansion theory are used to obtain the statistical moments and the probability density functions (PDFs of the OPF results. The proposed approach is examined and tested on a modified IEEE 34 node test feeder with integrated five different DG units. The obtained results prove the efficiency of the proposed approach to solve both deterministic and probabilistic OPF problems for different forms of the multi-objective function. As such, it can serve as a useful decision-making supporting tool for distribution network operators. [Projekat Ministarstva nauke Republike Srbije, br. TR33046
Uncertainty evaluation in BEACON power distribution monitoring
International Nuclear Information System (INIS)
BEACON is an advanced operational core support package that has a three-dimensional nodal code as its cornerstone. The three-dimensional calculation includes all necessary pressurized water reactor feedback effects. The generation of the measured power distribution from the core instrumentation is one of the primary functions of the core-monitoring software. The purpose of this paper is to discuss evaluation of the uncertainty in the measured assembly power from the BEACON system. The study covers not only the normal operating conditions, but off-normal situations to demonstrate BEACON's applicability for that condition
Decentralised electrical distribution network in power plants
International Nuclear Information System (INIS)
A centralised network is a dominating network solution in today's power plants. In this study a centralised and a decentralised network were designed in order to compare them economically and technically. The emphasis of this study was on economical aspects, but also the most important technical aspects were included. The decentralised network requires less space and less cabling since there is no switchgear building and distribution transformers are placed close to the consumption in the field of a power plant. MV-motors and distribution transformers build up a ring. Less cabling and an absent switchgear building cause considerable savings. Component costs of both of the networks were estimated by using data from fulfilled power plant projects and turned out to be smaller for the decentralised network. Simulations for the decentralised network were done in order to find a way to carry out earth fault protection and location. It was found out that in high resistance earthed system the fault distance can be estimated by a relatively simple method. The decentralised network uses a field bus, which offers many new features to the automation system of a power plant. Diversified information can be collected from the protection devices in order to schedule only the needed maintenance duties at the right time. Through the field bus it is also possible to control remotely a power plant. The decentralised network is built up from ready-to-install modules. These modules are tested by the module manufacturer decreasing the need for field testing dramatically. The work contribution needed in the electrification and the management of a power plant project reduces also due the modules. During the lifetime of a power plant, maintenance is easier and more economical. (orig.)
Security Constrained Distributed Optimal Power Flow of Interconnected Power Systems
Institute of Scientific and Technical Information of China (English)
BINKOU Alhabib; YU Yixin
2008-01-01
The security constrained distributed optimal power flow (DOPF) of interconnected power systems is presented. The centralized OPF problem of the multi-area power systems is decomposed into independent DOPF subproblems, one for each area. The dynamic security region (DSR) to guarantee the transient stability constraints and static voltage stability region (SVSR) constraints, and line current limits are included as constraints. The solutions to the DOPF subproblems of the different areas are coordinated through a pricing mechanism until they converge to the centralized OPF solution. The nonlinear DOPF subproblem is solved by predictor-corrector interior point method (PCIPM). The IEEE three-area RTS-96 system is worked out in order to demonstrate the effectiveness of the proposed method.
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 ...
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 ...
Electrical power systems for distributed generation
Energy Technology Data Exchange (ETDEWEB)
Robertson, T.A.; Huval, S.J. [Stewart & Stevenson Services, Inc., Houston, TX (United States)
1996-12-31
{open_quotes}Distributed Generation{close_quotes} has become the {open_quotes}buzz{close_quotes} word of an electric utility industry facing deregulation. Many industrial facilities utilize equipment in distributed installations to serve the needs of a thermal host through the capture of exhaust energy in a heat recovery steam generator. The electrical power generated is then sold as a {open_quotes}side benefit{close_quotes} to the cost-effective supply of high quality thermal energy. Distributed generation is desirable for many different reasons, each with unique characteristics of the product. Many years of experience in the distributed generation market has helped Stewart & Stevenson to define a range of product features that are crucial to most any application. The following paper will highlight a few of these applications. The paper will also examine the range of products currently available and in development. Finally, we will survey the additional services offered by Stewart & Stevenson to meet the needs of a rapidly changing power generation industry.
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.
Distributed power generation using biogas fuelled microturbines
International Nuclear Information System (INIS)
This research sought to analyse the market for small scale biogas fuelled distributed power generation, to demonstrate the concept of a biogas fuelled microturbine using the Capstone microturbine in conjunction with an anaerobic digester, and undertake a technico-economic evaluation of the biogas fuelled microturbine concept. Details are given of the experimental trials using continuous and batch digesters, and feedstocks ranging from cow and pig slurries to vegetable wastes and municipal solid waste. The yields of methane are discussed along with the successful operation of the microturbine with biogas fuels, and anaerobic digestion projects
Distributed power generation using biogas fuelled microturbines
Energy Technology Data Exchange (ETDEWEB)
Pointon, K.; Langan, M.
2002-07-01
This research sought to analyse the market for small scale biogas fuelled distributed power generation, to demonstrate the concept of a biogas fuelled microturbine using the Capstone microturbine in conjunction with an anaerobic digester, and undertake a technico-economic evaluation of the biogas fuelled microturbine concept. Details are given of the experimental trials using continuous and batch digesters, and feedstocks ranging from cow and pig slurries to vegetable wastes and municipal solid waste. The yields of methane are discussed along with the successful operation of the microturbine with biogas fuels, and anaerobic digestion projects.
Structure Learning in Power Distribution Networks
Energy Technology Data Exchange (ETDEWEB)
Deka, Deepjyoti [Univ. of Texas, Austin, TX (United States); Chertkov, Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Backhaus, Scott N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-01-13
Traditionally power distribution networks are either not observable or only partially observable. This complicates development and implementation of new smart grid technologies, such as these related to demand response, outage detection and management, and improved load-monitoring. Here, inspired by proliferation of the metering technology, we discuss statistical estimation problems in structurally loopy but operationally radial distribution grids consisting in learning operational layout of the network from measurements, e.g. voltage data, which are either already available or can be made available with a relatively minor investment. Our newly suggested algorithms apply to a wide range of realistic scenarios. The algorithms are also computationally efficient – polynomial in time – which is proven theoretically and illustrated computationally on a number of test cases. The technique developed can be applied to detect line failures in real time as well as to understand the scope of possible adversarial attacks on the grid.
International Nuclear Information System (INIS)
The nuclear safety analysis of spent fuel storages taking into account fuel burnup should allow for burnup distribution along the height of the assembly. We propose a method based on an analysis of the axial burnup profiles of spent fuel assemblies. This method can be used in nuclear safety justification of spent fuel management and storage systems
Energy Technology Data Exchange (ETDEWEB)
Snoj, Luka; Ravnik, Matjaz; Lengar, Igor [Jozef Stefan Institute, Reactor Physics Division, Jamova 39, SI-1000 Ljubljana (Slovenia)
2008-10-29
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 {approx}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)
Distributed Algorithms for Optimal Power Flow Problem
Lam, Albert Y S; Tse, David
2011-01-01
Optimal power flow (OPF) is an important problem for power generation and it is in general non-convex. With the employment of renewable energy, it will be desirable if OPF can be solved very efficiently so its solution can be used in real time. With some special network structure, e.g. trees, the problem has been shown to have a zero duality gap and the convex dual problem yields the optimal solution. In this paper, we propose a primal and a dual algorithm to coordinate the smaller subproblems decomposed from the convexified OPF. We can arrange the subproblems to be solved sequentially and cumulatively in a central node or solved in parallel in distributed nodes. We test the algorithms on IEEE radial distribution test feeders, some random tree-structured networks, and the IEEE transmission system benchmarks. Simulation results show that the computation time can be improved dramatically with our algorithms over the centralized approach of solving the problem without decomposition, especially in tree-structured...
Intelligent distributed control for nuclear power plants
International Nuclear Information System (INIS)
This project was initiated in September 1989 as a three year project to develop and demonstrate Intelligent Distributed Control (IDC) for Nuclear Power Plants. There were two primary goals of this research project. The first goal was to combine diagnostics and control to achieve a highly automated power plant as described by M.A. Schultz. The second goal was to apply this research to develop a prototype demonstration on an actual power plant system, the EBR-2 steam plant. Described in this Final (Third Annual) Technical Progress Report is the accomplishment of the project's final milestone, an in-plant intelligent control experiment conducted on April 1, 1993. The development of the experiment included: simulation validation, experiment formulation and final programming, procedure development and approval, and experimental results. Other third year developments summarized in this report are: (1) a theoretical foundation for Reconfigurable Hybrid Supervisory Control, (2) a steam plant diagnostic system, (3) control console design tools and (4) other advanced and intelligent control
Autonomous Active and Reactive Power Distribution Strategy in Islanded Microgrids
DEFF Research Database (Denmark)
Wu, Dan; Tang, Fen; Guerrero, Josep M.;
2014-01-01
(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...
Distributed Robust Power System State Estimation
Kekatos, Vassilis
2012-01-01
Deregulation of energy markets, penetration of renewables, advanced metering capabilities, and the urge for situational awareness, all call for system-wide power system state estimation (PSSE). Implementing a centralized estimator though is practically infeasible due to the complexity scale of an interconnection, the communication bottleneck in real-time monitoring, regional disclosure policies, and reliability issues. In this context, distributed PSSE methods are treated here under a unified and systematic framework. A novel algorithm is developed based on the alternating direction method of multipliers. It leverages existing PSSE solvers, respects privacy policies, exhibits low communication load, and its convergence to the centralized estimates is guaranteed even in the absence of local observability. Beyond the conventional least-squares based PSSE, the decentralized framework accommodates a robust state estimator. By exploiting interesting links to the compressive sampling advances, the latter jointly es...
Galileo spacecraft power management and distribution system
International Nuclear Information System (INIS)
It has been twelve years since two Voyager spacecraft began the direct route to the outer planets. In October 1989 a single Galileo spacecraft started the return to Jupiter. Conceived as a simple Voyager look-alike, the Galileo power management and distribution (PMAD) system has undergone many iterations in configuration. Major changes to the PMAD resulted from dual spun slip ring limitations, variations in launch vehicle thrust capabilities, and launch delays. Lack of an adequate launch vehicle for an interplanetary mission of Galileo's size has resulted in an extremely long flight duration. A Venus-Earth-Earth Gravity Assist (VEEGA) tour, vital to attain the required energy, results in a 6 year trip to Jupiter and its moons. This paper provides a description of the Galileo PMAD and documents the design drivers that established the final as-built hardware
Axial Halbach Magnetic Bearings
Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.
2008-01-01
Axial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active 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...
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. ...
Institute of Scientific and Technical Information of China (English)
李俊昌; 马琨; 樊则宾
2002-01-01
The vertical excitation axial-flux kilowatt CO2 laser is an equipment widely used in the high-power laser heat treatment industrial applications. The experimental measurements indicate that the power density distribution of laser beam is generally of ring distribution with a sunken at the center, therefore the laser beam cannot be simply regarded as base mode Gaussian beam. In this paper, such laser beam is regarded as the non-interference superposition of TEM00 and TEM01 mode beams, the method to determine the simulation parameters is discussed, and the relevant heat effect calculation equation is deduced.
DISTRIBUTED ELECTRICAL POWER PRODUCTION SYSTEM AND METHOD OF CONTROL THEREOF
DEFF Research Database (Denmark)
2010-01-01
The present invention relates to a distributed electrical power production system wherein two or more electrical power units comprise respective sets of power supply attributes. Each set of power supply attributes is associated with a dynamic operating state of a particular electrical power unit....
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 ...
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...
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...
International Nuclear Information System (INIS)
An important task in ensuring the operational safety of a nuclear power plant with a vessel-type water-cooled, water-moderated reactor is the development of algorithms for controlling power distribution in base-load and load-following regimes. The control strategy must ensure that the form of power distribution is maintained within the permissible limits in the case of situations presenting a nuclear hazard and of xenon fluctuations when there are variations in power output. The task of controlling power distribution can be broken down into an axial problem and a radial-azimuthal problem. For maintenance of the form of axial power distribution an algorithm of optimum fast-action control is proposed; for maintenance of the radial-azimuthal form, an algorithm of optimum (i.e. best) approximation to the given distribution of control. The two control problems are solved by using a single computerized procedure based on mathematical programming. The algorithms are designed for use in computerized control. The paper presents the results of algorithm simulation. The authors propose that in the first stage, activation of the control systems should involve the operator, who can view the sequence of actions on a display screen. (author)
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
Institute of Scientific and Technical Information of China (English)
WANG Yan; CUI Hai-qing; YANG Yuan-jian; GUO Jun-hui; LI Nan
2006-01-01
In this article, the governing equations for the unsteady flow of viscoelastic fluid in the eccentric annulus with the inner cylinder reciprocating axially and the expression of the pressure distribution on the wall of the inner cylinder of the annulus are established and derived, respectively, under the bipolar coordinate system.The equations and the expression are solved and calculated numerically using the finite difference method, respectively.The curves of the pressure distribution on the wall of the inner cylinder of the aqueous solution of Hydrolyzed Polyacrylamide (HPAM) are plotted and the influences of annular eccentricity, stroke, and stroke frequency on the pressure distribution are analyzed.
Wireless powering for low-power distributed sensors
Directory of Open Access Journals (Sweden)
Popović Zoya B.
2006-01-01
Full Text Available In this paper, an overview of the field of wireless powering is presented with an emphasis on low-power applications. Several rectenna elements and arrays are discussed in more detail: (1 a 10-GHz array for powering sensors in aircraft wings; (2 a single antenna in the 2.4-GHz ISM band for low-power assisted-living sensors; and (3 a broadband array for power harvesting in the 2-18GHz frequency range.
Shan Yang; Xiangqian Tong
2016-01-01
Power flow calculation and short circuit calculation are the basis of theoretical research for distribution network with inverter based distributed generation. The similarity of equivalent model for inverter based distributed generation during normal and fault conditions of distribution network and the differences between power flow and short circuit calculation are analyzed in this paper. Then an integrated power flow and short circuit calculation method for distribution network with inverte...
Specifying Processes: Application to Electrical Power Distribution
Directory of Open Access Journals (Sweden)
Sabah Al-Fedaghi
2011-01-01
Full Text Available Problem statement: This study deals with the problem of how to specify processes. Many process specification methodologies have been determined to be incomplete; for example, ISO 9000:2005 defines process as transforming media inputs into outputs. Nevertheless, the author of the Quality Systems Handbook, declares that such a definition is incomplete because processes create results and not necessarily by transforming inputs. Still, it is not clear what description of process can embed transformation of input to output or include creation that leads to results. Approach: This problem is important because process specification is an essential component in building projects utilized in such tasks as scheduling, planning, production, management, work flow and reengineering. Results: We solve the problem by opening the black box in the input-transformation-output model. This action uncovers many possible sources and destinations related to input and output, such as the disappearance, storage and copying of input. It is possible to reject input and also to block output from leaving the process. The approach is based on a conceptual framework for process specification of all generic phases that make up any process and embraces input, transformation, creation and output. The study applies the method in the field of electrical power distribution systems. Conclusion: We conclude that the results demonstrate a viable specification method that can be adopted for different types of processes.
The methodology of three dimensional core monitoring power distribution generation in SCOMS
Energy Technology Data Exchange (ETDEWEB)
Lee, Ki Bog; Kim, Keung Koo; In, Wang Kee; Zee, Sung Quun [Korea Atomic Energy Research Institute, Taejeon (Korea)
2002-03-01
This report provides the description of the methodology and main program module of power distribution calculation of SCOMS(SMART COre Monitoring System). The simulation results of the SMART core using the developed SCOMS are included. In this report, new methodology to calculate the three dimensional power distribution is developed. Core monitoring constants are calculated with the core design code(MASTER) which is on-line coupled with SCOMS. Three dimensional(3D) power distribution and the several peaking factors are calculated using the in-core detector signals and core monitoring constants provided at real time. Based on the various simulation results, it is founded that the three dimensional peaking factor to calculate the Linear Power Density and the pseudo hot-pin axial power distribution to calculate the Departure Nucleate Boiling Ratio show the more conservative values than those of the best-estimated core design code, and SCOMS adapted developed methodology can secures the more operation margin than the conventional methodology. 6 refs., 9 figs., 6 tabs. (Author)
Wind Farms’ Spatial Distribution Effect on Power System Reserves Requirements
DEFF Research Database (Denmark)
Sørensen, Poul Ejnar; Cutululis, Nicolaos Antonio
2010-01-01
in smaller areas, which causes the total wind power fluctuations in power system areas to increase significantly. The impact of future large wind farms spatial distribution with respect to the power system reserve requirements is analyzed in this paper. For this purpose, Correlated Wind (CorWind) power time...
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....
The Design of Power Distribution System for CYCIAE-100
Institute of Scientific and Technical Information of China (English)
GE; Tao; CAI; Hong-ru; LI; Zhen-guo
2012-01-01
<正>As an important component of CYCIAE-100, the power distribution system can be divided into four parts, i. e., RF system with a total power of 420 kW, water cooling system of 150 kW, vacuum system of 100 kW, and other devices with a total power of 450 kW. The design of power distribution system for CYCIAE-100 is based on three principles as listed below.
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.
Energy Technology Data Exchange (ETDEWEB)
Eriksson, Stefanie; Topgaard, Daniel, E-mail: daniel.topgaard@fkem1.lu.se [Division of Physical Chemistry, Department of Chemistry, Lund University, Lund (Sweden); Lasič, Samo [CR Development AB, Lund (Sweden); Nilsson, Markus [Lund University Bioimaging Center, Lund University, Lund (Sweden); Westin, Carl-Fredrik [Department of Radiology, BWH, Harvard Medical School, Boston, Massachusetts MA 02215 (United States); Department of Biomedical Engineering, Medical Informatics, Linköping University, Linköping (Sweden)
2015-03-14
We introduce a nuclear magnetic resonance method for quantifying the shape of axially symmetric microscopic diffusion tensors in terms of a new diffusion anisotropy metric, D{sub Δ}, which has unique values for oblate, spherical, and prolate tensor shapes. The pulse sequence includes a series of equal-amplitude magnetic field gradient pulse pairs, the directions of which are tailored to give an axially symmetric diffusion-encoding tensor b with variable anisotropy b{sub Δ}. Averaging of data acquired for a range of orientations of the symmetry axis of the tensor b renders the method insensitive to the orientation distribution function of the microscopic diffusion tensors. Proof-of-principle experiments are performed on water in polydomain lyotropic liquid crystals with geometries that give rise to microscopic diffusion tensors with oblate, spherical, and prolate shapes. The method could be useful for characterizing the geometry of fluid-filled compartments in porous solids, soft matter, and biological tissues.
Eriksson, Stefanie; Lasič, Samo; Nilsson, Markus; Westin, Carl-Fredrik; Topgaard, Daniel
2015-03-14
We introduce a nuclear magnetic resonance method for quantifying the shape of axially symmetric microscopic diffusion tensors in terms of a new diffusion anisotropy metric, DΔ, which has unique values for oblate, spherical, and prolate tensor shapes. The pulse sequence includes a series of equal-amplitude magnetic field gradient pulse pairs, the directions of which are tailored to give an axially symmetric diffusion-encoding tensor b with variable anisotropy bΔ. Averaging of data acquired for a range of orientations of the symmetry axis of the tensor b renders the method insensitive to the orientation distribution function of the microscopic diffusion tensors. Proof-of-principle experiments are performed on water in polydomain lyotropic liquid crystals with geometries that give rise to microscopic diffusion tensors with oblate, spherical, and prolate shapes. The method could be useful for characterizing the geometry of fluid-filled compartments in porous solids, soft matter, and biological tissues. PMID:25770532
Energy Technology Data Exchange (ETDEWEB)
Ferrouk, M. [Laboratoire du Genie Physique des Hydrocarbures, University of Boumerdes, Boumerdes 35000 (Algeria)], E-mail: m_ferrouk@yahoo.fr; Aissani, S. [Laboratoire du Genie Physique des Hydrocarbures, University of Boumerdes, Boumerdes 35000 (Algeria); D' Auria, F.; DelNevo, A.; Salah, A. Bousbia [Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione, Universita di Pisa (Italy)
2008-10-15
The present article covers the evaluation of the performance of twelve critical heat flux methods/correlations published in the open literature. The study concerns the simulation of an axially non-uniform heat flux distribution with the RELAP5 computer code in a single boiling water reactor channel benchmark problem. The nodalization scheme employed for the considered particular geometry, as modelled in RELAP5 code, is described. For this purpose a review of critical heat flux models/correlations applicable to non-uniform axial heat profile is provided. Simulation results using the RELAP5 code and those obtained from our computer program, based on three type predictions methods such as local conditions, F-factor and boiling length average approaches were compared.
International Nuclear Information System (INIS)
The present article covers the evaluation of the performance of twelve critical heat flux methods/correlations published in the open literature. The study concerns the simulation of an axially non-uniform heat flux distribution with the RELAP5 computer code in a single boiling water reactor channel benchmark problem. The nodalization scheme employed for the considered particular geometry, as modelled in RELAP5 code, is described. For this purpose a review of critical heat flux models/correlations applicable to non-uniform axial heat profile is provided. Simulation results using the RELAP5 code and those obtained from our computer program, based on three type predictions methods such as local conditions, F-factor and boiling length average approaches were compared
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
Directory of Open Access Journals (Sweden)
Cristiano M. A. de Souza
2001-12-01
Full Text Available O objetivo deste trabalho foi determinar a potência necessária para acionamento de uma colhedora de fluxo axial para feijão. Testes experimentais foram conduzidos, sendo determinados o torque e a rotação na tomada de potência do trator, a força necessária para arrastar a máquina, a velocidade de trabalho, a quantidade de produto colhido e o tempo necessário para colhê-lo. Para se estudar o comportamento das variáveis investigadas, realizaram-se análises de metodologia de superfície de resposta. A potência exigida no motor do trator para tracionar a colhedora, com carregamento máximo do tanque graneleiro, foi equivalente a 7,90 kW e o acionamento dos órgãos internos demandou 45,28 kW. A potência total exigida pela máquina foi de 53,18 kW. A maior capacidade de colheita foi 6,56 t h-1 e o consumo específico de energia apresentou valor mínimo de 2,46 kWh t-1.The objective of this work was to find the power requirement for operating an axial flow bean harvester. Experimental tests were performed, the torque and angular velocity in the power take-off (PTO, the drawbar force, the machine speed and harvesting capacity were measured. To analyze the effect of the variables on the power needed, regression analysis were done. The drawbar power for the maximum grain bin capacity was 7.90 kW. The maximum PTO power to operate the machine was found to be 45.28 kW. The maximum harvesting capacity was 6.56 t h-1. The minimum specific energy consumption was 2.46 kWh t-1.
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.
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...
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...
Local Control of Reactive Power by Distributed Photovoltaic Generators
Turitsyn, Konstantin S; Backhaus, Scott; Chertkov, Misha
2010-01-01
High penetration levels of distributed photovoltaic (PV) generation on an electrical distribution circuit may severely degrade power quality due to voltage sags and swells caused by rapidly varying PV generation during cloud transients coupled with the slow response of existing utility compensation and regulation equipment. Although not permitted under current standards for interconnection of distributed generation, fast-reacting, VAR-capable PV inverters may provide the necessary reactive power injection or consumption to maintain voltage regulation under difficult transient conditions. As side benefit, the control of reactive power injection at each PV inverter provides an opportunity and a new tool for distribution utilities to optimize the performance of distribution circuits, e.g. by minimizing thermal losses. We suggest a local control scheme that dispatches reactive power from each PV inverter based on local instantaneous measurements of the real and reactive components of the consumed power and the re...
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...
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
Options for Control of Reactive Power by Distributed Photovoltaic Generators
Sulc, Petr; Backhaus, Scott; Chertkov, Michael
2010-01-01
High penetration levels of distributed photovoltaic(PV) generation on an electrical distribution circuit present several challenges and opportunities for distribution utilities. Rapidly varying irradiance conditions may cause voltage sags and swells that cannot be compensated by slowly responding utility equipment resulting in a degradation of power quality. Although not permitted under current standards for interconnection of distributed generation, fast-reacting, VAR-capable PV inverters may provide the necessary reactive power injection or consumption to maintain voltage regulation under difficult transient conditions. As side benefit, the control of reactive power injection at each PV inverter provides an opportunity and a new tool for distribution utilities to optimize the performance of distribution circuits, e.g. by minimizing thermal losses. We discuss and compare via simulation various design options for control systems to manage the reactive power generated by these inverters. An important design de...
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.
TS Seminar: Overview of Fermilab’s Power Distribution System
CERN. Geneva
2006-01-01
A 27.5 km2 (6800 acre) site is powered by two 345 kV, two 34.5 kV, one 12.4 kV and five 7.2 kV lines. The talk gives an overview of Fermilab’s power distribution system with emphasis on accelerator power. The accelerator power distribution system provides 13.8 kV power to all accelerators and conventional loads. Design criteria, design features and operational experience are given.Organiser(s): F. Rodriguez-Mateos & Emmanuel Tsesmelis
Energy Technology Data Exchange (ETDEWEB)
Rivera, Fernando F. [Departamento de Quimica, Universidad Autonoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, C.P. 09340, Mexico, D.F. (Mexico); Cruz-Diaz, Martin R., E-mail: mcruz@tese.edu.m [Division de Quimica y Bioquimica, Tecnologico de Estudios Superiores de Ecatepec, Av. Tecnologico S/N Esq. Av. Hank Gonzalez, Valle de Anahuac, C.P. 55120, Ecatepec, Edo. de Mex (Mexico); Rivero, Eligio P. [Departamento de Ingenieria y Tecnologia, Universidad Nacional Autonoma de Mexico, Facultad de Estudios Superiores Cuautitlan, Av. Primero de Mayo, Cuautitlan Izcalli, C.P. 54740, Edo. de Mex (Mexico); Gonzalez, Ignacio [Departamento de Quimica, Universidad Autonoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, C.P. 09340, Mexico, D.F. (Mexico)
2010-12-15
The liquid phase mixing flow pattern at low (20 < Re < 120) and intermediate liquid flow rate (120 < Re < 400) was studied by means of residence time distribution (RTD) experimental curve in an up-flow Filter Press electrochemical reactor (FM01-LC) bench scale. For this purpose, a plastic turbulence promoter was used with stainless-steel and platinised titanium structural meshes as electrodes in channel configuration. To visualize and determine the mixing flow pattern in the liquid phase, the stimulus-response technique was employed using dextran blue (D{sub M} = 1.058 x 10{sup -11} m{sup 2} s{sup -1}, 25 {sup o}C, in water) as model tracer. A theoretical analysis and approximation RTD experimental curves with axial dispersion model (ADM) and plug dispersion exchange model (PDE), with 'closed-closed vessel' boundary conditions were used in order to establish a better approximation of the axial dispersion, stagnant zones, channelling and by-pass (preference flow) effects present at low and intermediate Re. RTD curves show that the liquid flow pattern in the FM01-LC deviates considerably from axial dispersion model at low Re, where the FM01-LC exhibits large channelling, stagnant zones, and dead zone. The PDE model represents fairly this deviation from ideal flow (less dead zone).
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.
Parallel and distributed processing: applications to power systems
Energy Technology Data Exchange (ETDEWEB)
Wu, Felix; Murphy, Liam [California Univ., Berkeley, CA (United States). Dept. of Electrical Engineering and Computer Sciences
1994-12-31
Applications of parallel and distributed processing to power systems problems are still in the early stages. Rapid progress in computing and communications promises a revolutionary increase in the capacity of distributed processing systems. In this paper, the state-of-the art in distributed processing technology and applications is reviewed and future trends are discussed. (author) 14 refs.,1 tab.
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 (input voltage of +/-3 V. This result offers a viable way for the fabrication of a high-performance high-density logic circuit using a low-temperature fabrication process, which makes it suitable for flexible electronics.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 (input voltage of +/-3 V. This result offers a viable way for the fabrication of a high-performance high-density logic circuit using a low-temperature fabrication process, which makes it suitable for flexible electronics. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01040g
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
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...
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.
Statistical analyses support power law distributions found in neuronal avalanches.
Directory of Open Access Journals (Sweden)
Andreas Klaus
Full Text Available The size distribution of neuronal avalanches in cortical networks has been reported to follow a power law distribution with exponent close to -1.5, which is a reflection of long-range spatial correlations in spontaneous neuronal activity. However, identifying power law scaling in empirical data can be difficult and sometimes controversial. In the present study, we tested the power law hypothesis for neuronal avalanches by using more stringent statistical analyses. In particular, we performed the following steps: (i analysis of finite-size scaling to identify scale-free dynamics in neuronal avalanches, (ii model parameter estimation to determine the specific exponent of the power law, and (iii comparison of the power law to alternative model distributions. Consistent with critical state dynamics, avalanche size distributions exhibited robust scaling behavior in which the maximum avalanche size was limited only by the spatial extent of sampling ("finite size" effect. This scale-free dynamics suggests the power law as a model for the distribution of avalanche sizes. Using both the Kolmogorov-Smirnov statistic and a maximum likelihood approach, we found the slope to be close to -1.5, which is in line with previous reports. Finally, the power law model for neuronal avalanches was compared to the exponential and to various heavy-tail distributions based on the Kolmogorov-Smirnov distance and by using a log-likelihood ratio test. Both the power law distribution without and with exponential cut-off provided significantly better fits to the cluster size distributions in neuronal avalanches than the exponential, the lognormal and the gamma distribution. In summary, our findings strongly support the power law scaling in neuronal avalanches, providing further evidence for critical state dynamics in superficial layers of cortex.
Distribution of wind power resource over Pakistan
Energy Technology Data Exchange (ETDEWEB)
Nasir, S.M.; Raza, S.M.; Raja, I.A. (Balochistan Univ., Quetta (Pakistan). Dept. of Physics)
1992-01-01
The synthesis and presentation of the wind data are required to establish the wind resource climatology for an area. In this respect, wind contour maps are essential to visualize and quantify the variation of wind speed over the country. Using the average data from 59 locations, iso-wind speed contours are drawn by constructing monthly and yearly maps. The most suitable period for utilizing wind potential is May-August. During this period, the country as a whole exhibits the best wind resource potential, with an average speed of about 3 m/s. (3 m/s average wind speed is very poor for wind power generation). The most promising regions for exploiting wind power throughout the year are the coastline, lower Sind and north-western Balochistan. (author).
Solar concentrators with adjustable power density distributions
Energy Technology Data Exchange (ETDEWEB)
Kleinwaechter, J.
1977-09-01
Solar concentrators are described which provide given power density in the absorber. According to the invention, 'semi-optical' lenses and mirrors are used to concentrate the incident solar radiation; these elements image the solar disk not as a point but as an area of constant illumination intensity on the absorber. This is achieved by a functional locus-dependecy of refraction and reflection. For mirror concentration, a differential equation is given which satisfies this functional dependency.
Location Refinement and Power Coverage Analysis Based on Distributed Antenna
Institute of Scientific and Technical Information of China (English)
赵晓楠; 侯春萍; 汪清; 陈华; 浦亮洲
2016-01-01
To establish wireless channel suitable for the cabin environment, the power coverage was investigated with distributed antenna system and centralized antenna system based on the actual measurement of channel im-pulse response. The results indicated that the distributed antenna system has more uniform power coverage than the centralized antenna system. The average relative errors of receiving power of both antennas were calculated. The optimal position of the centralized antenna was obtained by Gaussian function refinement, making the system achieve a better transmission power with the same coverage effect, and providing a reference for antenna location in the future real communication in the cabin.
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.
Power Capability in Low Voltage DC Distribution Systems
Directory of Open Access Journals (Sweden)
C.O. Gecan
2009-12-01
Full Text Available Recent developments in power electronics components enable the use of power electronics in Low Voltage (LV networks. This development makes the model of a Low Voltage Direct Current (LVDC distribution system possible. The technical and economical benefits of this technology make possible the alternative hypothesis of using DC instead of AC distribution systems. Some aspects, such as increasing the capability of the existing lines, interconnecting distributed generation units and even supplying in DC some loads are creating additional requirements of using a LVDC distribution system. The paper presents some general considerations regarding cables used in a LVAC distribution system and different line reconfigurations witch enable the use of cobles in a LVDC distribution system. The reconfigurations are presented in respect of the DC network topologies: unipolar and bipolar. The central aim of this paper is to investigate capability of power transmission and to calculate the transmission distance for cables used in Low Voltage AC and DC distribution systems. Capability computation is considered in respect of two constrains imposed in the cables cross section selection: cable thermal limit and the maximum allowable voltage drop. Cable thermal limit is represented in calculations by the maximum rated current. The equations used to calculate the power capability are presented for single-phase and threephase AC networks and unipolar and bipolar DC networks. Based on these equations, comparisons between power capability of cables with different cross sections used in Low Voltage DC and AC distribution systems are realized and presented.
Calculated CIM Power Distributions for Coil Design
International Nuclear Information System (INIS)
Excessive bed expansion and material expulsion have occurred during experiments with the 3-inch diameter Cylindrical Induction Melter (CIM). Both events were attributed in part to the high power density in the bottom of the melter and the correspondingly high temperatures there. It is believed that the high temperatures resulted in the generation of gasses at the bottom of the bed which could not escape. The gasses released during heating and the response of the bed to gas evolution depend upon the composition of the bed
Energy Technology Data Exchange (ETDEWEB)
Kallio, S. [Aabo Akademi, Turku (Finland). Inst. of Heat Engineering
1997-10-01
The project has concentrated on the study of the parameters affecting the drag correlations by examining the behaviour of the axial density profiles and especially the steady-state regions in different flow conditions both experimentally and theoretically. The empirical data analysed in this work is collected from hot conditions in a CFB pilot scale combustor. The data consists of pressure profiles and other macroscopic measurements from different flow conditions. In the analysis of the data and in the modelling work empirical methods such as neural network modelling have been used. The results show that the drag correlations written for cold conditions can be adapted to hot conditions by taking into account the change in the terminal velocity of a single particle. (orig.)
Shuttle Electrical Power Analysis Program (SEPAP) distribution circuit analysis report
Torina, E. M.
1975-01-01
An analysis and evaluation was made of the operating parameters of the shuttle electrical power distribution circuit under load conditions encountered during a normal Sortie 2 Mission with emphasis on main periods of liftoff and landing.
Communication Systems and Study Method for Active Distribution Power systems
DEFF Research Database (Denmark)
Wei, Mu; Chen, Zhe
Due to the involvement and evolvement of communication technologies in contemporary power systems, the applications of modern communication technologies in distribution power system are becoming increasingly important. In this paper, the International Organization for Standardization (ISO......) reference seven-layer model of communication systems, and the main communication technologies and protocols on each corresponding layer are introduced. Some newly developed communication techniques, like Ethernet, are discussed with reference to the possible applications in distributed power system....... The suitability of the communication technology to the distribution power system with active renewable energy based generation units is discussed. Subsequently the typical possible communication systems are studied by simulation. In this paper, a novel method of integrating communication system impact into power...
Energy loss analysis of an integrated space power distribution system
Kankam, M. David; Ribeiro, P. F.
1992-01-01
The results of studies related to conceptual topologies of an integrated utility-like space power system are described. The system topologies are comparatively analyzed by considering their transmission energy losses as functions of mainly distribution voltage level and load composition. The analysis is expedited by use of a Distribution System Analysis and Simulation (DSAS) software. This recently developed computer program by the Electric Power Research Institute (EPRI) uses improved load models to solve the power flow within the system. However, present shortcomings of the software with regard to space applications, and incompletely defined characteristics of a space power system make the results applicable to only the fundamental trends of energy losses of the topologies studied. Accountability, such as included, for the effects of the various parameters on the system performance can constitute part of a planning tool for a space power distribution system.
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.
A Multi-Functional Power Electronic Converter in Distributed Generation Power Systems
DEFF Research Database (Denmark)
Chen, Zhe; Blaabjerg, Frede; Pedersen, John Kim
2005-01-01
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 harmonic components...
Operation of Modern Distribution Power Systems in Competitive Electricity Markets
DEFF Research Database (Denmark)
Hu, Weihao
In this dissertation, the characteristics of a distribution system under a dynamic electricity-pricing, load management system and under a large number of power electronic interfaced distributed generation units are investigated. The operation characteristics of a power system with wind turbines......, DG units, loads and electricity price are studied. Further, the effect of energy storage systems will be considered, and an optimal operation strategy for energy storage devices in a large scale wind power system in the electricity market is proposed. The western Danish power system, which has large...... penetrations of variable wind power production and may represent the future electricity markets in some ways, is chosen as the studied power system. 10 year actual data from the Danish competitive electricity market are collected and analyzed. The relationship among the electricity price, the consumption...
The effects of transients on photospheric and chromospheric power distributions
Samanta, T; Banerjee, D; Prasad, S Krishna; Mathioudakis, M; Jess, D; Pant, V
2016-01-01
We have observed a quiet Sun region with the Swedish 1-meter Solar Telescope (SST) equipped with CRISP Imaging SpectroPolarimeter. High-resolution, high-cadence, H$\\alpha$ line scanning images were taken to observe different layers of the solar atmosphere from the photosphere to upper chromosphere. We study the distribution of power in different period-bands at different heights. Power maps of the upper photosphere and the lower chromosphere show suppressed power surrounding the magnetic-network elements, known as "magnetic shadows". These also show enhanced power close to the photosphere, traditionally referred to as "power halos". The interaction between acoustic waves and inclined magnetic fields is generally believed to be responsible for these two effects. In this study we explore if small-scale transients can influence the distribution of power at different heights. We show that the presence of transients, like mottles, Rapid Blueshifted Excursions (RBEs) and Rapid Redshifted Excursions (RREs), can stro...
Directory of Open Access Journals (Sweden)
Shan Yang
2016-01-01
Full Text Available Power flow calculation and short circuit calculation are the basis of theoretical research for distribution network with inverter based distributed generation. The similarity of equivalent model for inverter based distributed generation during normal and fault conditions of distribution network and the differences between power flow and short circuit calculation are analyzed in this paper. Then an integrated power flow and short circuit calculation method for distribution network with inverter based distributed generation is proposed. The proposed method let the inverter based distributed generation be equivalent to Iθ bus, which makes it suitable to calculate the power flow of distribution network with a current limited inverter based distributed generation. And the low voltage ride through capability of inverter based distributed generation can be considered as well in this paper. Finally, some tests of power flow and short circuit current calculation are performed on a 33-bus distribution network. The calculated results from the proposed method in this paper are contrasted with those by the traditional method and the simulation method, whose results have verified the effectiveness of the integrated method suggested in this paper.
The Power-law Tail Exponent of Income Distributions
Clementi, F; Gallegati, M
2006-01-01
In this paper we tackle the problem of estimating the power-law tail exponent of income distributions by using the Hill's estimator. A subsample semi-parametric bootstrap procedure minimising the mean squared error is used to choose the power-law cutoff value optimally. This technique is applied to personal income data for Australia and Italy.
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
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.
Sensitivity of the power distribution in large heterogeneous LMFBR designs
Energy Technology Data Exchange (ETDEWEB)
Tzanos, C.P.; Barthold, W.P.
1977-01-01
In heterogeneous LMFBR designs consisting of consecutive core and blanket zones, the power distribution is very sensitive to enrichment distribution changes in the core zones. The purpose of the paper is to analyze this sensitivity in heterogeneous LMFBR designs of different degrees of coupling among the core zones.
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.
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.
AC Power Routing System in Home Based on Demand and Supply Utilizing Distributed Power Sources
Directory of Open Access Journals (Sweden)
Takashi Hikihara
2011-04-01
Full Text Available To help reduce consumption of fossil fuels, renewable, natural and distributed power sources are being adopted. These alternative energy sources inevitably show fluctuations in the amount of output power, frequency, and voltage. The suppression of such fluctuations is a key issue to avoid disturbances in power grids. A similar situation arises as far as the regulation of in-home power flow is concerned. We focus on the quality of supplied and demanded power in particular. In this paper, an in-home power distribution system based on information of power is proposed. The system is developed in order to integrate power dispatch and communication. The experimental results show the feasibility of new flexible and efficient power management approaches.
Site selection of active damper for stabilizing power electronics based power distribution system
DEFF Research Database (Denmark)
Yoon, Changwoo; Wang, Xiongfei; Bak, Claus Leth;
2015-01-01
Stability in the nowadays distribution power system is endangered by interaction problems that may arise from newly added power-electronics based power devices. Recently, a new concept to deal with this higher frequency instability, the active damper, has been proposed. The active damper is a pow...
Econophysical anchoring of unimodal power-law distributions
Eliazar, Iddo I.; Cohen, Morrel H.
2013-09-01
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.
Carolus, Thomas
The paper examines the acoustic and aerodynamic performance of low-pressure axial fan rotors with a hub/tip ratio of 0.45. Six rotors were designed for the same working point by means of the well-known airfoil theory. The condition of an equilibrium between the static pressure gradient and the centrifugal forces is maintained. All rotors have unequally spaced blades to diminish tonal noise. The rotors are tested in a short cylindrical housing without guide vanes. All rotors show very similar flux-pressure difference characteristics. The peak efficiency and the noise performance is considerably influenced by the chosen blade design. The aerodynamically and acoustically optimal rotor is the one with the reduced load at the hub and increased load in the tip region under satisfied equilibrium conditions. It runs at the highest aerodynamic efficiency, and its noise spectrum is fairly smooth. The overall sound pressure level of this rotor is up to 8 dB (A) lower compared to the other rotors under consideration.
Broadening of axial neutron flux difference operating band in Angra I
International Nuclear Information System (INIS)
ANGRA I Technical Specifications requires the axial flux difference to remain within ± 5 percent band, relative to a reference value, for any power level. The reference value is the axial flux difference at a 100% power, all rods (almost) out and equilibrium Xenon distribution. This paper presents the results of several Simulations, performed by FURNAS staff aiming the validation of calculation results against the reload designer's ones. It was also proved that the Axial Flux Difference Operating band can be broadened to ''Ref. +- 6.9% ) without exce eding the limit imposed by the ''envelope-curve''. (author)
Evaluation of Current Controllers for Distributed Power Generation Systems
DEFF Research Database (Denmark)
Timbus, Adrian; Liserre, Marco; Teodorescu, Remus;
2009-01-01
This paper discusses the evaluation of different current controllers employed for grid-connected distributed power generation systems having variable input power, such as wind turbines and photovoltaic systems. The focus is mainly set on linear controllers such as proportional-integral, proportio......This paper discusses the evaluation of different current controllers employed for grid-connected distributed power generation systems having variable input power, such as wind turbines and photovoltaic systems. The focus is mainly set on linear controllers such as proportional....... First, in steady-state conditions, the contribution of controllers to the total harmonic distortion of the grid current is pursued. Further on, the behavior of controllers in the case of transient conditions like input power variations and grid voltage faults is also examined. Experimental results in...
Optimal Operation of Energy Storage in Power Transmission and Distribution
Akhavan Hejazi, Seyed Hossein
In this thesis, we investigate optimal operation of energy storage units in power transmission and distribution grids. At transmission level, we investigate the problem where an investor-owned independently-operated energy storage system seeks to offer energy and ancillary services in the day-ahead and real-time markets. We specifically consider the case where a significant portion of the power generated in the grid is from renewable energy resources and there exists significant uncertainty in system operation. In this regard, we formulate a stochastic programming framework to choose optimal energy and reserve bids for the storage units that takes into account the fluctuating nature of the market prices due to the randomness in the renewable power generation availability. At distribution level, we develop a comprehensive data set to model various stochastic factors on power distribution networks, with focus on networks that have high penetration of electric vehicle charging load and distributed renewable generation. Furthermore, we develop a data-driven stochastic model for energy storage operation at distribution level, where the distribution of nodal voltage and line power flow are modelled as stochastic functions of the energy storage unit's charge and discharge schedules. In particular, we develop new closed-form stochastic models for such key operational parameters in the system. Our approach is analytical and allows formulating tractable optimization problems. Yet, it does not involve any restricting assumption on the distribution of random parameters, hence, it results in accurate modeling of uncertainties. By considering the specific characteristics of random variables, such as their statistical dependencies and often irregularly-shaped probability distributions, we propose a non-parametric chance-constrained optimization approach to operate and plan energy storage units in power distribution girds. In the proposed stochastic optimization, we consider
An Effective Distributed Model for Power System Transient Stability Analysis
Directory of Open Access Journals (Sweden)
MUTHU, B. M.
2011-08-01
Full Text Available The modern power systems consist of many interconnected synchronous generators having different inertia constants, connected with large transmission network and ever increasing demand for power exchange. The size of the power system grows exponentially due to increase in power demand. The data required for various power system applications have been stored in different formats in a heterogeneous environment. The power system applications themselves have been developed and deployed in different platforms and language paradigms. Interoperability between power system applications becomes a major issue because of the heterogeneous nature. The main aim of the paper is to develop a generalized distributed model for carrying out power system stability analysis. The more flexible and loosely coupled JAX-RPC model has been developed for representing transient stability analysis in large interconnected power systems. The proposed model includes Pre-Fault, During-Fault, Post-Fault and Swing Curve services which are accessible to the remote power system clients when the system is subjected to large disturbances. A generalized XML based model for data representation has also been proposed for exchanging data in order to enhance the interoperability between legacy power system applications. The performance measure, Round Trip Time (RTT is estimated for different power systems using the proposed JAX-RPC model and compared with the results obtained using traditional client-server and Java RMI models.
Power allocation strategies for distributed precoded multicell based systems
Directory of Open Access Journals (Sweden)
Silva Adão
2011-01-01
Full Text Available Abstract Multicell cooperation is a promising solution for cellular wireless systems to mitigate intercell interference, improve system fairness, and increase capacity. In this article, we propose power allocation techniques for the downlink of distributed, precoded, multicell cellular-based systems. The precoder is designed in two phases: first the intercell interference is removed by applying a set of distributed precoding vectors; then the system is further optimized through power allocation. Three centralized power allocation algorithms with per-BS power constraint and different complexity trade-offs are proposed: one optimal in terms of minimization of the instantaneous average bit error rate (BER, and two suboptimal. In this latter approach, the powers are computed in two phases. First, the powers are derived under total power constraint (TPC and two criterions are considered, namely, minimization of the instantaneous average BER and minimization of the sum of inverse of signal-to-noise ratio. Then, the final powers are computed to satisfy the individual per-BS power constraint. The performance of the proposed schemes is evaluated, considering typical pedestrian scenarios based on LTE specifications. The numerical results show that the proposed suboptimal schemes achieve a performance very close to the optimal but with lower computational complexity. Moreover, the performance of the proposed per-BS precoding schemes is close to the one obtained considering TPC over a supercell.
Power Quality Analysis Using Bilinear Time-Frequency Distributions
Directory of Open Access Journals (Sweden)
Sha'ameri AhmadZuri
2010-01-01
Full Text Available Abstract Bilinear time-frequency distributions (TFDs are powerful techniques that offer good time and frequency resolution of time-frequency representation (TFR. It is very appropriate to analyze power quality signals which consist of nonstationary and multi-frequency components. However, the TFDs suffer from interference because of cross-terms. Many TFDs have been implemented, and there is no fixed window or kernel that can remove the cross-terms for all types of signals. In this paper, the bilinear TFDs are implemented to analyze power quality signals such as smooth-windowed Wigner-Ville distribution (SWWVD, Choi-Williams distribution (CWD, B-distribution (BD, and modified B-distribution (MBD. The power quality signals focused are swell, sag, interruption, harmonic, interharmonic, and transient based on IEEE Std, 1159-1995. A set of performance measures is defined and used to compare the TFRs. It shows that SWWVD presents the best performance and is selected for power quality signal analysis. Thus, an adaptive optimal kernel SWWVD is designed to determine the separable kernel automatically from the input signal.
Mitra, Parag
The past few decades have seen a consistent growth of distributed PV sources. Distributed PV, like other DG sources, can be located at or near load centers and provide benefits which traditional generation may lack. However, distribution systems were not designed to accommodate such power generation sources as these sources might lead to operational as well as power quality issues. A high penetration of distributed PV resources may lead to bi-directional power flow resulting in voltage swells, increased losses and overloading of conductors. Voltage unbalance is a concern in distribution systems and the effect of single-phase residential PV systems on voltage unbalance needs to be explored. Furthermore, the islanding of DGs presents a technical hurdle towards the seamless integration of DG sources with the electricity grid. The work done in this thesis explores two important aspects of grid inte-gration of distributed PV generation, namely, the impact on power quality and anti-islanding. A test distribution system, representing a realistic distribution feeder in Arizona is modeled to study both the aforementioned aspects. The im-pact of distributed PV on voltage profile, voltage unbalance and distribution sys-tem primary losses are studied using CYMDIST. Furthermore, a PSCAD model of the inverter with anti-island controls is developed and the efficacy of the anti-islanding techniques is studied. Based on the simulations, generalized conclusions are drawn and the problems/benefits are elucidated.
The Effects of Transients on Photospheric and Chromospheric Power Distributions
Samanta, T.; Henriques, V. M. J.; Banerjee, D.; Krishna Prasad, S.; Mathioudakis, M.; Jess, D.; Pant, V.
2016-09-01
We have observed a quiet-Sun region with the Swedish 1 m Solar Telescope equipped with the CRISP Imaging SpectroPolarimeter. High-resolution, high-cadence, Hα 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 whether 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 strongly influence the power maps. The short and finite lifetime of these events strongly affects all power maps, potentially influencing the observed power distribution. We show that Doppler-shifted transients like RBEs and RREs that occur ubiquitously can have a dominant effect on the formation of the power halos in the quiet Sun. For magnetic shadows, transients like mottles do not seem to have a significant effect on the power suppression around 3 minutes, and wave interaction may play a key role here. Our high-cadence observations reveal that flows, waves, and shocks manifest in the presence of magnetic fields to form a nonlinear magnetohydrodynamic system.
Power laws in citation distributions: Evidence from Scopus
Brzezinski, Michal
2014-01-01
Modeling distributions of citations to scientific papers is crucial for understanding how science develops. However, there is a considerable empirical controversy on which statistical model fits the citation distributions best. This paper is concerned with rigorous empirical detection of power-law behaviour in the distribution of citations received by the most highly cited scientific papers. We have used a large, novel data set on citations to scientific papers published between 1998 and 2002 drawn from Scopus. The power-law model is compared with a number of alternative models using a likelihood ratio test. We have found that the power-law hypothesis is rejected for around half of the Scopus fields of science. For these fields of science, the Yule, power-law with exponential cut-off and log-normal distributions seem to fit the data better than the pure power-law model. On the other hand, when the power-law hypothesis is not rejected, it is usually empirically indistinguishable from most of the alternative mo...
Mahoney, John J; Dugan, Paul D; Budinger, Raymond E; Goelzer, H Fred
1950-01-01
A 30-inch tip-diameter axial-flow compressor stage was investigated with and without rotor to determine individual blade-row performance, interblade-row effects, and outer-wall boundary-layer conditions. Velocity gradients at guide-vane outlet without rotor approximated design assumptions, when the measured variation of leaving angle was considered. With rotor in operation, Mach number and rotor-blade effects changed flow distribution leaving guide vanes and invalidated design assumption of radial equilibrium. Rotor-blade performance correlated interpolated two-dimensional results within 2 degrees, although tip stall was indicated in experimental and not two-dimensional results. Boundary-displacement thickness was less than 1.0 and 1.5 percent of passage height after guide vanes and after rotor, respectively, but increased rapidly after rotor when tip stall occurred.
Enhancement of Distributed Generation by Using Custom Power Device
Institute of Scientific and Technical Information of China (English)
Kishor V. Bhadane; M. S. Ballal; R. M. Moharil
2015-01-01
Abstract-Wind energy (WE) has become immensely popular for distributed generation (DG). This case presents the monitoring, modeling, control, and analysis of the two-level three-phase WE based DG system where the electric grid interfacing custom power device (CPD) is controlled to perform the smart exchanging of electric power as per the Indian grid code. WE is connected to DC link of CPD for the grid integration purpose. The CPD based distributed static compensator, i.e. the distributed static synchronous compensator (DSTATCOM), is utilized for injecting the wind power to the point of common coupling (PCC) and also acts against the reactive power demand. The novel indirect current control scheme of DSTATCOM regulates the power import and export between the WE and the electric grid system. It also acts as a compensator and performs both the key features simultaneously. Hence, the penetration of additional generated WE power to the grid is increased by 20% to 25%. The burden of reactive power compensation from grid is reduced by DSTATCOM. The modeling and simulation are done in MATLAB. The results are validated and verified.
Distribution-Agnostic Stochastic Optimal Power Flow for Distribution Grids: Preprint
Energy Technology Data Exchange (ETDEWEB)
Baker, Kyri; Dall' Anese, Emiliano; Summers, Tyler
2016-09-01
This paper outlines a data-driven, distributionally robust approach to solve chance-constrained AC optimal power flow problems in distribution networks. Uncertain forecasts for loads and power generated by photovoltaic (PV) systems are considered, with the goal of minimizing PV curtailment while meeting power flow and voltage regulation constraints. A data- driven approach is utilized to develop a distributionally robust conservative convex approximation of the chance-constraints; particularly, the mean and covariance matrix of the forecast errors are updated online, and leveraged to enforce voltage regulation with predetermined probability via Chebyshev-based bounds. By combining an accurate linear approximation of the AC power flow equations with the distributionally robust chance constraint reformulation, the resulting optimization problem becomes convex and computationally tractable.
Radiated power distributions in impurity-seeded plasmas in LHD
Energy Technology Data Exchange (ETDEWEB)
Morisaki, T., E-mail: morisaki@nifs.ac.jp [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Nagoya University, Nagoya 464-8602 (Japan); Oyama, K. [Nagoya University, Nagoya 464-8602 (Japan); Tamura, N.; Masuzaki, S.; Akiyama, T.; Motojima, G.; Miyazawa, J.; Peterson, B.J. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Ohno, N. [Nagoya University, Nagoya 464-8602 (Japan); Yamada, H. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan)
2015-08-15
In LHD, impurity seeding has been performed to enhance the radiative cooling in the edge region. Neon, nitrogen and argon were seeded by gas puffing, and the behaviour of those impurities in the plasma was investigated with the innovative diagnostic method. Two bolometer arrays were used to measure the two-dimensional radiated power distribution. Using the tomographic technique, radiated power distributions on a poloidal plane can be obtained with the high time resolution. During the discharge with neon puff, considerable radiation from the core region was observed, in addition to the strong edge radiation. In spite of the highly radiated power, plasma did not result in the radiation collapse. On the other hand, in the nitrogen-seeded discharge, the strong radiation only from the peripheral region was observed. Different time evolutions of the total radiated power between neon and nitrogen seeded discharges were observed after stopping each impurity puff.
Power-law distributions in binned empirical data
Virkar, Yogesh
2012-01-01
Many man-made and natural phenomena, including the intensity of earthquakes, population of cities, and size of international wars, are believed to follow power-law distributions. The accurate identification of power-law patterns has significant consequences for developing an understanding of complex systems. However, statistical evidence for or against the power-law hypothesis is complicated by large fluctuations in the empirical distribution's tail, and these are worsened when information is lost from binning the data. We adapt the statistically principled framework for testing the power-law hypothesis, developed by Clauset, Shalizi and Newman, to the case of binned data. This approach includes maximum-likelihood fitting, a hypothesis test based on the Kolmogorov-Smirnov goodness-of-fit statistic and likelihood ratio tests for comparing against alternative explanations. We evaluate the effectiveness of these methods on synthetic binned data with known structure and apply them to twelve real-world binned data...
Power distribution from insertion device x-ray sources
International Nuclear Information System (INIS)
Insertion device (ID) synchrotron x-ray sources on present day and next-generation synchrotron facilities have very attractive spectral properties. In addition however, they are capable of producing x-ray beams with large powers and in some cases, unprecedented power densities. An overview of the spatial and frequency distributions of these sources including the effects of synchrotron particle beam emittance is presented
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 ...
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...
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...
Power-law distribution in Japanese racetrack betting
Ichinomiya, Takashi
2006-01-01
Gambling is one of the basic economic activities that humans indulge in. An investigation of gambling activities provides deep insights into the economic actions of people and sheds lights on the study of econophysics. In this paper we present an analysis of the distribution of the final odds of the races organized by the Japan Racing Association. The distribution of the final odds $P_o(x)$ indicates a clear power law $P_o(x)\\propto 1/x$, where $x$ represents the final odds. This power law ca...
Power-Law Tail in the Chinese Wealth Distribution
Institute of Scientific and Technical Information of China (English)
DING Ning; WANG You-Gui
2007-01-01
@@ We analyse the data from the recently published lists of the richest Chinese from the year 2003 to 2005. The results confirm that in these years the wealth is distributed according to a power law with exponents between 1.758 and 2.285 in the high end. The power distribution is found to be quite robust although the persons in the list change drastically and the wealth increases rapidly. The relation between the wealth and the absolute change of wealth rejects the notion that the wealth evolution is a multiplicative stochastic process.
Power corrections and renormalons in Transverse Momentum Distributions
Scimemi, Ignazio
2016-01-01
We study power corrections to Transverse Momentum Distributions (TMDs) by analyzing renormalon divergences of the perturbative series. The renomalon divergences arise independently in two constituents of TMDs: the rapidity evolution kernel and the small-b matching coefficient. The renormalon contributions have a non-trivial dependence on the Bjorken variable and the transverse distance. We discuss the consistency requirements for power corrections for TMDs and suggest inputs for the TMD phenomenology in accordance with this study. Both unpolarized quark TMD parton distribution function and fragmentation function are considered.
Power distribution for the ATLAS LAr Trigger Digitizer Board
International Nuclear Information System (INIS)
The R and D activity for the design of the power distribution section of the ATLAS Liquid Argon (LAr) Calorimeter Trigger Digitizer Board board (LTDB) is presented. Many aspects concerning the radiation hardness and the ability to operate Point-of-load converters also in presence of high magnetic fields are covered. Devices designed by CERN for experiments at LHC have been used and their capability for implementation in the LTDB has been exploited with the aim to have a power distribution section with the required performances
Population distribution analyses for nuclear power plant siting
Energy Technology Data Exchange (ETDEWEB)
Durfee, R.C.; Coleman, P.R.
1983-12-01
The Nuclear Regulatory Commission is in the process of reviewing guidelines and regulations associated with population distribution criteria around nuclear power plant sites. The purpose of this paper is to describe the methodology for calculating population distributions in the US and then evaluating specific population criteria and their effect upon the selection of future nuclear power plant sites. Through the use of computer systems, different alternatives may be evaluated for individual sites or for major regions of the country to determine their restrictiveness on siting nuclear plants. Two types of criteria were used. They involved the analysis of population distributions radially out from each possible site and the study of angular distributions around each site. Results are presented in both tabular and graphic form using national, regional, and site-level computer maps. 5 references, 39 figures, 8 tables.
The California power crisis: the role for distributed generation
International Nuclear Information System (INIS)
This article examines the impact of the California power crisis on cogeneration and the on-site generation market, and highlights the plight of independent power generators including cogeneration facilities who have typically long-term contracts with the cash-strapped state electric utilities and have to defer maintenance due to unpaid bills. The move towards distributed generation, the efforts to increase backup diesel-fired generation during blackouts, and the government's efforts to encourage distributed energy are discussed along with the concerns of air quality regulators with on-site generation emissions, and the impact of the California crisis on the future of distributed energy. The growing role of distributed energy in meeting demand and holding down costs is explored, and the expanding market for microturbines is noted
Space craft thermal thermionic reactors with flat power distribution
International Nuclear Information System (INIS)
The nuclear reactors are potential candidates for energy generation in space missions over longer periods where high power output is required. Among different nuclear energy conversion options, the statical ones, such as thermo-electric or thermionic reactors, are preferable in order to avoid the kinetic disturbances of the space craft and furthermore in order to reduce the failure probabilities to a minimum, caused by lubricants and seals. In the present study, the main parameters of different types of thermal thermionic reactors are discussed which are fueled with U-233 or U-235 and moderated with ZrH1.7 or Beryllium. The investigated thermionic reactors will be layed out to have a constant heat production density on the emitter surface over the space variable, so as to achieve a maximum engineering efficiency with respect to the electrical conversion, nuclear fuel utilization, material damage, thermal and radiation gradients. The power flattening procedure is performed by varying the moderator to fuel ratio, both in axial and radial directions
Dynamic voltage regulation and power export in a distribution system using distributed generation
Institute of Scientific and Technical Information of China (English)
Aamir HANIF; Muhammad Ahmed CHOUDHRY
2009-01-01
The major aim of power quality (PQ) enhancing techniques is to maintain a specified voltage magnitude at a desired frequency for sensitive loads irrespective of faults on the power distribution network. The dynamic voltage restorer (DVR) is a device used to mitigate voltage sags to regulate load voltage. This paper presents a mathematical model for leading series voltage injection to mitigate sags thereby achieving the improvement of the utility power factor as well as power sharing between the DVR and utility. The power sharing will be as per requirement to compensate the sags considering the available distributed generation (DG). The approach of mitigating voltage sags using the concept of leading series voltage injection is suitable for those locations where phase shift in the voltage will not cause any problem. The MATLAB/SIMULINK SimPowerSystem toolbox has been used to obtain simulation results to verify the proposed mathematical model.
Thresholded Power Law Size Distributions of Instabilities in Astrophysics
Aschwanden, Markus J
2015-01-01
Power law-like size distributions are ubiquitous in astrophysical instabilities. There are at least four natural effects that cause deviations from ideal power law size distributions, which we model here in a generalized way: (1) a physical threshold of an instability; (2) incomplete sampling of the smallest events below a threshold $x_0$; (3) contamination by an event-unrelated background $x_b$; and (4) truncation effects at the largest events due to a finite system size. These effects can be modeled in simplest terms with a "thresholded power law" distribution function (also called generalized Pareto [type II] or Lomax distribution), $N(x) dx \\propto (x+x_0)^{-a} dx$, where $x_0 > 0$ is positive for a threshold effect, while $x_0 < 0$ is negative for background contamination. We analytically derive the functional shape of this thresholded power law distribution function from an exponential-growth evolution model, which produces avalanches only when a disturbance exceeds a critical threshold $x_0$. We app...
Power distribution monitoring and control in 500 MWe PHWR
International Nuclear Information System (INIS)
The 500 MWe Indian Pressurized Heavy Water Reactor (PHWR) is expected to be commissioned in a few years. It has a relatively large sized core with complex material distribution in comparison to the currently operating 220 MWe PHWRs. The resulting neutronically loosely coupled system demands continuous control of the core power distribution. This paper gives a brief description and analysis of the reactor monitoring and control system proposed for this reactor. (author). 11 refs, 8 figs, 3 tabs
Silicon Carbide Based Power Mangement and Distribution for Space Nuclear Power Systems Project
National Aeronautics and Space Administration — In this SBIR project, APEI, Inc. is proposing to develop a high efficiency, rad-hard, 100's kWe power management and distribution (PMAD) system for space nuclear...
Wind Power Forecasting Error Distributions: An International Comparison; Preprint
Energy Technology Data Exchange (ETDEWEB)
Hodge, B. M.; Lew, D.; Milligan, M.; Holttinen, H.; Sillanpaa, S.; Gomez-Lazaro, E.; Scharff, R.; Soder, L.; Larsen, X. G.; Giebel, G.; Flynn, D.; Dobschinski, J.
2012-09-01
Wind power forecasting is expected to be an important enabler for greater penetration of wind power into electricity systems. Because no wind forecasting system is perfect, a thorough understanding of the errors that do occur can be critical to system operation functions, such as the setting of operating reserve levels. This paper provides an international comparison of the distribution of wind power forecasting errors from operational systems, based on real forecast data. The paper concludes with an assessment of similarities and differences between the errors observed in different locations.
International Nuclear Information System (INIS)
An advancement or variety of PWR cores by introducing MOX fuel, burnable poison and so on, increases a heterogeneity in a core or an assembly. For the evaluation of the pin power distribution, the fine mesh flux reconstruction is required with the combination of an assembly calculation and a three dimensional core calculation with coarse mesh, instead of the combination of a two dimensional X-Y core calculation with fine mesh and a one dimensional axial core calculation for the conventional PWR core. The main purpose of the NEANSC benchmark problems entitled 'Power Distribution within Assemblies' is to compare the technique of the fine mesh flux reconstruction based on coarse mesh core calculation. In this report, we examine the validity of the reconstruction technique based on the coarse mesh core calculation using the Spline function, assembly calculation and heterogeneous fine mesh core calculation by built-in programs in the SRAC code using the groupwise Monte Carlo calculation with the GMVP code as reference. (author)
Novel DC/DC Converters For High-Power Distributed Power Systems
Francisco Venustiano, Canales Abarca
2003-01-01
One of the requirements for the next generation of power supplies for distributed power systems (DPSs) is to achieve high power density with high efficiency. In the traditional front-end converter based on the two-stage approach for high-power three-phase DPSs, the DC-link voltage coming from the power factor correction (PFC) stage penalizes the second-stage DC/DC converter. This DC/DC converter not only has to meet the characteristics demanded by the load, but also must process energy w...
Camacho Santiago, Antonio; Castilla Fernández, Miguel; Miret Tomàs, Jaume; Guzmán Solà, Ramon; Borrell Sanz, Angel
2014-01-01
Grid faults are one of the most severe problems for network operation. Distributed generation power plants can help to mitigate the adverse effects of these perturbations by injecting reactive power during the sag and the post-fault operation. Thus, the risk of cascade disconnection and voltage collapse can be reduced. The proposed reactive power control is intended to regulate the maximum and minimum phase voltages at the point of common coupling within the limits established in grid codes f...
Designing concept on lightning protection of overhead power distribution line
Energy Technology Data Exchange (ETDEWEB)
Yokoyama, Shigeru [Central Research Institute of Electric Power Industry, Kanagawa-ken (Japan)], E-mail: yokoyama@criepi.denken.or.jp
2007-07-01
The principle is shown for lightning protection of power distribution lines taking the effects of surge arresters, overhead ground wires and their combined use into consideration. Moreover an outline of a rational design method targeting direct lightning hits, induced over voltages and back flow currents from high structures. (author)
Synchronization Methods for Three Phase Distributed Power Generation Systems
DEFF Research Database (Denmark)
Timbus, Adrian Vasile; Teodorescu, Remus; Blaabjerg, Frede;
2005-01-01
Nowadays, it is a general trend to increase the electricity production using Distributed Power Generation Systems (DPGS) based on renewable energy resources such as wind, sun or hydrogen. If these systems are not properly controlled, their connection to the utility network can generate problems...
High Resolution PV Power Modeling for Distribution Circuit Analysis
Energy Technology Data Exchange (ETDEWEB)
Norris, B. L.; Dise, J. H.
2013-09-01
NREL has contracted with Clean Power Research to provide 1-minute simulation datasets of PV systems located at three high penetration distribution feeders in the service territory of Southern California Edison (SCE): Porterville, Palmdale, and Fontana, California. The resulting PV simulations will be used to separately model the electrical circuits to determine the impacts of PV on circuit operations.
Distributed Generation Using Indirect Matrix Converter in Reverse Power Mode
DEFF Research Database (Denmark)
Liu, Xiong; Chiang Loh, Poh; Wang, Peng;
2013-01-01
not appropriate. Like most power converters, the operation of the IMC can surely be reversed to produce a boosted gain, but so far its relevant control principles have not been discussed. These challenges are now addressed in this paper with distributed generation suggested as a potential application. Simulation...
PHEMT Distributed Power Amplifier Adopting Broadband Impedance Transformer
DEFF Research Database (Denmark)
Narendra, K.; Limiti, E.; Paoloni, C.;
2013-01-01
A non-uniform drain line distributed power amplifier (DPA) employing a broadband impedance transformer is presented. The DPA is based on GaAs PHEMT technology. The impedance transformer employs asymmetric coupled lines and transforms a low output impedance of the amplifier to a standard 50 Ω...
Energy cost saving strategies in distributed power networks
Directory of Open Access Journals (Sweden)
Tcheukam Alain
2016-01-01
Full Text Available In this paper we study energy cost saving strategies in power networks in presence of prosumers. Three tips are considered: (i distributed power network architecture, (ii peak energy shaving with the integration of prosumers’ contribution, (iii Electric vehicles self-charging by means of prosumers’ production. The proposed distributed power network architecture reduces significantly the transmission costs and can reduce significantly the global energy cost up to 42 percent. Different types of prosumer who use self-charging photovoltaic systems, are able to intelligently buy energy from, or sell it, to the power grid. Therein, prosumers interact in a distributed environment during the purchase or sale of electric power using a double auction with negotiation mechanism. Using a two-step combined learning and optimization scheme, each prosumer can learn its optimal bidding strategy and forecast its energy production, consumption and storage. Our simulation results, conducted for the region of Sicily in Italy, show that the integration of prosumers can reduce peak hour costs up to 19 percent and 6 percent for eligible prosumers with electric vehicles.
Energy Technology Data Exchange (ETDEWEB)
Smith, R.S.; Hanan, N.A. [Argonne National Lab., IL (United States)
1998-07-01
Existing thermal hydraulics computer codes can account for variations in power and temperature in the axial and thickness directions but variations across the width of the plate cannot be accounted for. In the case of fuel plates in an annular core this can lead to significant errors which are accentuated by the presence of an oxide layer that builds up on the aluminium cladding with burnup. This paper uses a three dimensional SINDA model to account for the transverse variations in power. The effect of oxide thickness on these differences is studied in detail. Power distribution and fuel conductivity are also considered. The lower temperatures predicted with the SNDA model result in a greater margin to clad and fuel damage. (author)
Energy Technology Data Exchange (ETDEWEB)
Smith, R. S.
1998-10-27
Existing thermal hydraulics computer codes can account for variations in power and temperature in the axial and thickness directions but variations across the width of the plate cannot be accounted for. In the case of fuel plates in an annular core this can lead to significant errors which are accentuated by the presence of an oxide layer that builds up on the aluminum cladding with burnup. This paper uses a three dimensional SINDA model to account for the transverse variations in power. The effect of oxide thickness on these differences is studied in detail. Power distribution and fuel conductivity are also considered. The lower temperatures predicted with the SINDA model result in a greater margin to clad and fuel damage.
International Nuclear Information System (INIS)
Existing thermal hydraulics computer codes can account for variations in power and temperature in the axial and thickness directions but variations across the width of the plate cannot be accounted for. In the case of fuel plates in an annular core this can lead to significant errors which are accentuated by the presence of an oxide layer that builds up on the aluminium cladding with burnup. This paper uses a three dimensional SINDA model to account for the transverse variations in power. The effect of oxide thickness on these differences is studied in detail. Power distribution and fuel conductivity are also considered. The lower temperatures predicted with the SNDA model result in a greater margin to clad and fuel damage. (author)
Energy Technology Data Exchange (ETDEWEB)
Davis, M. W.; Broadwater, R.; Hambrick, J.
2007-07-01
This report summarizes the development of models for distributed generation and distribution circuit voltage regulation equipment for unbalanced power systems and their verification through actual field measurements.
Directory of Open Access Journals (Sweden)
Abbas A.H.
2016-01-01
Full Text Available A laboratory scale bubbling fluidized bed combustor was designed and fabricated to study the combustion of dewatered poultry sludge at different operational parameters. This paper present a study on the influence of equivalent ratio, secondary to primary air ratio and the fuel feed rate on the temperature distribution along the combustor. The equivalent ratio has been changed between 0.8 to 1.4% under poultry sludge feed rate of 10 kg/h and from 0.8 to 1 under poultry sludge feed rate of 15 kg/h. The secondary to primary air ratio was varied from 0.1 to 0.5 at 0.65 m injection height and 1.25 equivalent ratio. The results showed that these factors had a significant influence on the combustion characteristics of poultry sludge. The temperature distribution along the combustor was found to be strongly dependent on the fuel feed rate and the equivalent ratio and it increased when these two factors increased. However, the secondary air ratio increased the temperature in the lower region of the combustor while no significant effect was observed at the upper region of the combustor. The results suggested that the poultry sludge can be used as a fuel with high thermal combustor efficiency.
Electron beam machining using rotating and shaped beam power distribution
Elmer, John W.; O'Brien, Dennis W.
1996-01-01
An apparatus and method for electron beam (EB) machining (drilling, cutting and welding) that uses conventional EB guns, power supplies, and welding machine technology without the need for fast bias pulsing technology. The invention involves a magnetic lensing (EB optics) system and electronic controls to: 1) concurrently bend, focus, shape, scan, and rotate the beam to protect the EB gun and to create a desired effective power-density distribution, and 2) rotate or scan this shaped beam in a controlled way. The shaped beam power-density distribution can be measured using a tomographic imaging system. For example, the EB apparatus of this invention has the ability to drill holes in metal having a diameter up to 1000 .mu.m (1 mm or larger), compared to the 250 .mu.m diameter of laser drilling.
Agent Based Control of Electric Power Systems with Distributed Generation
DEFF Research Database (Denmark)
Saleem, Arshad
Distributed generation, decentralized and local control, self organization and autonomy are evident trends of today's electric power systems focusing on innovative control architectures such as MicroGrids, Virtual Power Plants, Cell based systems, plug-in electric vehicles and real time markets...... and subsystems that are able to coordinate, communicate, cooperate, adapt to emerging situations and self organize in an intelligent way. At the same time, rapid development in information and and communication technologies (ICT) have brought new opportunities and elucidations. New Technologies and standards...... have been developed particularly in the area of communication and distributed control. Electric power industry is eager to explore, evaluate and adopt these new advancements in ICT for improving its current practices of automation and control in order to cope with above mentioned challenges...
Transverse Vibration of Axially Moving Functionally Graded Materials Based on Timoshenko Beam Theory
Directory of Open Access Journals (Sweden)
Suihan Sui
2015-01-01
Full Text Available The transverse free vibration of an axially moving beam made of functionally graded materials (FGM is investigated using a Timoshenko beam theory. Natural frequencies, vibration modes, and critical speeds of such axially moving systems are determined and discussed in detail. The material properties are assumed to vary continuously through the thickness of the beam according to a power law distribution. Hamilton’s principle is employed to derive the governing equation and a complex mode approach is utilized to obtain the transverse dynamical behaviors including the vibration modes and natural frequencies. Effects of the axially moving speed and the power-law exponent on the dynamic responses are examined. Some numerical examples are presented to reveal the differences of natural frequencies for Timoshenko beam model and Euler beam model. Moreover, the critical speed is determined numerically to indicate its variation with respect to the power-law exponent, axial initial stress, and length to thickness ratio.
Distributed continuous energy scheduling for dynamic virtual power plants
International Nuclear Information System (INIS)
This thesis presents DynaSCOPE as distributed control method for continuous energy scheduling for dynamic virtual power plants (DVPP). DVPPs aggregate the flexibility of distributed energy units to address current energy markets. As an extension of the Virtual Power Plant concept they show high dynamics in aggregation and operation of energy units. Whereas operation schedules are set up for all energy units in a day-ahead planning procedure, incidents may render these schedules infeasible during execution, like deviation from prognoses or outages. Thus, a continuous scheduling process is needed to ensure product fulfillment. With DynaSCOPE, software agents representing single energy units solve this problem in a completely distributed heuristic approach. Using a stepped concept, several damping mechanisms are applied to allow minimum disturbance while continuously trying to fulfill the product as contracted at the market.
Parallel and distributed processing in power system simulation and control
Energy Technology Data Exchange (ETDEWEB)
Falcao, Djalma M. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia
1994-12-31
Recent advances in computer technology will certainly have a great impact in the methodologies used in power system expansion and operational planning as well as in real-time control. Parallel and distributed processing are among the new technologies that present great potential for application in these areas. Parallel computers use multiple functional or processing units to speed up computation while distributed processing computer systems are collection of computers joined together by high speed communication networks having many objectives and advantages. The paper presents some ideas for the use of parallel and distributed processing in power system simulation and control. It also comments on some of the current research work in these topics and presents a summary of the work presently being developed at COPPE. (author) 53 refs., 2 figs.
Distribution of Acoustic Power Spectra for an Isolated Helicopter Fuselage
Directory of Open Access Journals (Sweden)
Kusyumov A.N.
2016-01-01
Full Text Available The broadband aerodynamic noise can be studied, assuming isotropic flow, turbulence and decay. Proudman’s approach allows practical calculations of noise based on CFD solutions of RANS or URANS equations at the stage of post processing and analysis of the solution. Another aspect is the broadband acoustic spectrum and the distribution of acoustic power over a range of frequencies. The acoustic energy spectrum distribution in isotropic turbulence is non monotonic and has a maximum at a certain value of Strouhal number. In the present work the value of acoustic power peak frequency is determined using a prescribed form of acoustic energy spectrum distribution presented in papers by S. Sarkar and M. Y. Hussaini and by G. M. Lilley. CFD modelling of the flow around isolated helicopter fuselage model was considered using the HMB CFD code and the RANS equations.
Is cortical distribution of spectral power a stable individual characteristic?
Knyazev, Gennady G
2009-05-01
General understanding in EEG research is that cortical distribution of spectral power varies as a function of time, frequency, state, and experimental condition. There are findings, however, which show that individual-specific patterns of cortical spectral power distribution could be amazingly stable, at least in some experimental conditions. In this study two different experimental datasets were used to analyze stability and variability of individual pattern of cortical spectral power distribution across time, experimental conditions, and frequency bands. First experiment consisted of presentation of pictures of emotional facial expressions. Second experiment was an auditory stop-signal task. In both experiments a number of psychometric measures were obtained from each participant. It has been shown that in spite of high short-term variability, individual-specific patterns of cortical spectral power distribution are remarkably stable across frequency bands, long periods of time, and experimental conditions. These patterns are related to state and trait participant's characteristics. The antero-posterior spectral power gradient emerged as the most prominent feature associated with important personality dimensions. Relatively higher oscillatory activity in the frontal cortical region relates to female gender and Behavioral Inhibition tendencies. Relatively higher activity at posterior sites is associated with Extraversion. Significant differences in event-related spectral perturbations upon presentation of emotionally loaded stimuli were found between high and low antero-posterior gradient participants. These data show that cortical distribution of oscillatory activity may be seen as a relatively stable individual characteristic. Enhanced or diminished oscillatory activity of some cortical regions, such as the prefrontal cortex, may play an important role in organization of human behavior. PMID:19047002
PWR power distribution flattening using Quantum Particle Swarm intelligence
International Nuclear Information System (INIS)
Highlights: ► Quantum Particle Swarm Optimization (QPSO) is applied to ICFMO. ► A differential mutation operator is added to enhance QPSO performance (QPSO-DM). ► PSO, QPSO and QPSO-DM are tested on Bushehr Nuclear Power Plant (BNPP). ► It is observed that QPSO-DM is comparable to PSO and QPSO on ICFMO. - Abstract: In-core fuel management optimization (ICFMO) is one of the most challenging concepts of nuclear engineering. Most of the strategies implemented for optimizing fuel loading pattern in nuclear power reactors are based on maximizing core multiplication factor in order to extract maximum energy and reducing power peaking factor from a predetermined value to maintain fuel integrity. In this investigation a new method using Quantum Particle Swarm Optimization (QPSO) algorithm has been developed in order to flatten power density distribution in WWER-1000 Bushehr Nuclear Power Plant (BNPP) and thereby provide a better safety margin. The result and convergence of this method show that QPSO performs very well and is comparable to PSO. Furthermore, an operator has been added to QPSO as a mutation operator. This algorithm, called QPSO-DM, shows a better performance on ICFMO than PSO and QPSO. MATLAB software was used to map PSO, QPSO and QPSO-DM for loading pattern optimization. Multi-group constants generated by WIMS for different fuel configurations were fed into CITATION to obtain the power density distribution
Institute of Scientific and Technical Information of China (English)
SHI Zongqian; LIU Zhigang; JIA Shenli; SONG Xiaochuan; WANG Lijun
2009-01-01
Effect of the axial magnetic field (AMF) on resisting the constriction of a high-current vacuum arc is studied in this paper. Two typical AMF distributions were investigated, i.e., the traditional bell-shaped AMF, and the saddle-shaped AMF. Experiments were conducted in a detachable vacuum chamber with a rms arc current in the range of 10 kA to 25 kA. The arc column was photographed by a high-speed digital camera with an exposure time of 2 microseconds. The constriction of the vacuum arc was compared by processing the images of the arc column under the two different field configurations and numerically determining the dimensions of the arc column near the electrodes. It was also confirmed that the AMF distribution had a signifcant influence on its effectiveness in resisting arc constriction, Furthermore, the AMF strength near the periphery of the arc is more influential than that at the centre of the electrodes in resisting arc constriction.
Power distribution unfolding on the basis of in-core rhodium powered detector readings
International Nuclear Information System (INIS)
The task of unfolding of core power distribution for WWER reactors consists of processing of Self Powered Neutron Detector measurements to obtain estimated values for the uninstrumented assemblies. The method described in the report relies on 3-D power distributions calculated with BIPR-5 code and adjusted to instrumented assemblies to reproduce SPND measurements. The multiplicative modifying function is used for this purpose. Earlier a simple method was proposed and evaluated, in which measured power densities served as internal boundary conditions in the BIPR-5 calculations of the 3-D distributions for the entire core. Both methods have been tested using data from Loviisa-1 reactor core, consisting of 349 hexagonal fuel assemblies, each 14.7 cm across and 250 cm in length (active length). The SPNDs were placed on 4 levels: 50, 100, 150, 200 cm above the bottom of reactor core in 36 instrumented assemblies. Refs, figs and tabs
Energy Technology Data Exchange (ETDEWEB)
Stosic, Zoran V. [Framatome ANP GmbH . NBTT, Erlangen (Germany)], e-mail: Zoran.Stosic@Framatome-ANP.de; Stevanovic, Vladimir D. [Framatome ANP GmbH, Erlangen (Germany); Iguchi, Tadashi [Japan Atomic Energy Research Institute (JAERI), Ibaraki (Japan)
2001-07-01
The influence of spatial power generation shape on thermal-hydraulics behaviour of the fuel rod bundle has been investigated. Particularly, the occurrence of the local Boiling Transition has been analysed, indicating that conditions for the Critical Heat Flux (CHF) are reached somewhere within the boiling water channels in the assembly. The two-phase coolant flow within the bundle is represented with the two-fluid model in 3D space. The porous medium concept is applied in the simulation of the two-phase flow through the rod bundle implying nonequilibrium thermal and flow conditions. The governing equations in three-dimensions are discretized with the control volume method. The 3D numerical simulation and analyses of thermal-hydraulics in a complex geometry of an advanced nuclear fuel assembly are performed for conditions of a partial and/or complete rods uncovering indicating occurrence of high quality CHF - Dryout. The obtained results from numerical simulations are compared with experimental Critical Power data obtained from full scale tests. Employed is an electrically heated test rod bundle with real 1:1 geometry. Different radial and axial power distributions are used with wide range of inlet mass flow rates (2 - 19 kg/s) and coolant inlet subcooling (25 - 185 kJ/kg). The coolant pressure, equal to 6.9 MPa, is typical for BWRs conditions. Comparison of the predicted Critical Power values with measured data shows encouraging agreements for all analysed power distributions and the results completely reflect measured two-phase mixture cross flows, steam void distribution and spatial positions of Dryout onsets. Based on performed numerical investigation, an improvement of Dryout criteria is proposed. Dynamic effects of power shape change on spatial thermal hydraulics and hence on CHF occurrence as well as the influence of transfer function on thermal hydraulics under cyclic power and/or flow rate changes are also being analysed. Experiments for such verifications
Characterizations of the power distribution by record values
Indian Academy of Sciences (India)
Min-Young Lee
2016-05-01
Let $\\{ X_n, n \\geq 1\\}$ be a sequence of i.i.d. random variables which has absolutely continuous distribution function $F(x)$ with probability density function $f(x)$ and $F(0) = 0$. Assume that $X_n$ belongs to the class $C^\\ast_1$ or $C_2$. Then $X_k$ has the power distribution if and only if $X_k$ and $\\frac{X_{L(n+1)}}{X_{L(n)}}$ or $\\frac{X_{L(n+1)}}{X_{L(n)}}$ and $\\frac{X_{L(n)}}{X_{L(n--1)}}$ are identically distributed, respectively. Suppose that $X_n$ belongs to the class $C_3$. Also, $X_k$ has the power distribution if and only if $X_{L(n+1)}$ and $X_{L(n)}\\cdot V$ are identically distributed, where $V$ is independent of $X_{L(n)}$ and $X_{L(n+1)}$ and is distributed as $X_n$’s.
Multi-Objective Reactive Power Optimization of Distribution Network with Distributed Generation
Directory of Open Access Journals (Sweden)
Zhao Hui
2016-01-01
Full Text Available Distributed generation (DG is considered to be a very promising alternative of power generation because of its tremendous environmental, social, and economic benefits. But the randomness and intermittent of DGs brings new problems to the system. This paper analyzes the reactive power optimization problem of distribution network with correlative DGs based on scenario analysis method. A new scenario division rule according to the joint distribution function of wind-PV power outputs is proposed in the paper. Then a multi-objective reactive power optimization model whose objects include the minimum active power losses, the minimum voltage deviation and the maximum static voltage stability margin is established. Non-dominated sorting genetic algorithm-II is used to solve the model. At the last of the paper, the model and the algorithm proposed are verified with an improved IEEE 33-bus system. The results show that the model will be a reference to the reactive power optimization problem in distribution system.
Directory of Open Access Journals (Sweden)
P.NIRMALA
2014-09-01
Full Text Available Modern power utilities have to respond to a number of challenges such as growth of electricity demand specially in non-linear loads in power grids, consequently, That higher power quality should be considered. In this paper, DPFC which is similar to unified power flow controller (UPFC in structure, which is used to mitigate the voltage sag and swell as a power quality issue. Unlike UPFC, the common dc-link in DPFC, between the shunt and series converter devices should be eliminated and three-phase series converter is divided to several single-phase series distributed converters through the power transmission line. And also to detect the voltage sags and find out the three single-phase reference voltages of DPFC, the synchronous reference frame method is proposed. Application of DPFC in power quality enhancement is simulated in Mat lab/Simulink environment which show the effectiveness of the proposed structure
Chattanooga Electric Power Board Case Study Distribution Automation
Energy Technology Data Exchange (ETDEWEB)
Glass, Jim [Chattanooga Electric Power Board (EPB), TN (United States); Melin, Alexander M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Starke, Michael R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2016-10-01
In 2009, the U.S. Department of Energy under the American Recovery and Reinvestment Act (ARRA) awarded a grant to the Chattanooga, Tennessee, Electric Power Board (EPB) as part of the Smart Grid Investment Grant Program. The grant had the objective “to accelerate the transformation of the nation’s electric grid by deploying smart grid technologies.” This funding award enabled EPB to expedite the original smart grid implementation schedule from an estimated 10-12 years to 2.5 years. With this funding, EPB invested heavily in distribution automation technologies including installing over 1,200 automated circuit switches and sensors on 171 circuits. For utilities considering a commitment to distribution automation, there are underlying questions such as the following: “What is the value?” and “What are the costs?” This case study attempts to answer these questions. The primary benefit of distribution automation is increased reliability or reduced power outage duration and frequency. Power outages directly impact customer economics by interfering with business functions. In the past, this economic driver has been difficult to effectively evaluate. However, as this case study demonstrates, tools and analysis techniques are now available. In this case study, the impact on customer costs associated with power outages before and after the implementation of distribution automation are compared. Two example evaluations are performed to demonstrate the benefits: 1) a savings baseline for customers under normal operations1 and 2) customer savings for a single severe weather event. Cost calculations for customer power outages are performed using the US Department of Energy (DOE) Interruption Cost Estimate (ICE) calculator2. This tool uses standard metrics associated with outages and the customers to calculate cost impact. The analysis shows that EPB customers have seen significant reliability improvements from the implementation of distribution automation. Under
Energy Technology Data Exchange (ETDEWEB)
NONE
2000-02-29
The open distributed automatic power distribution systems were delivered to Naha and Gushikawa branches of Okinawa Electric Power Co. This system adopts such latest technologies as object-oriented design. Its features are as follows: (1) Possible parallel operation by every branch and business office by switching an operation priority between the branch and business office in the case of multi- accidents, (2) Possible free console operation for any businesses regardless of the other console conditions, (3) Automatic decision of power supply by mobile power vehicle for precise power interruption control, (4) Immediate display of the work planning system including data maintenance and operation procedures until the prearranged working date, and (5) Possible manned backup operation at system down of the server. (translated by NEDO)
Reconstructing the galaxy redshift distribution from angular cross power spectra
Sun, L; Tao, C
2015-01-01
The control of photometric redshift (photo-$z$) errors is a crucial and challenging task for precision weak lensing cosmology. The spacial cross-correlations (equivalently, the angular cross power spectra) of galaxies between tomographic photo-$z$ bins are sensitive to the true redshift distribution $n_i(z)$ of each bin and hence can help calibrate the photo-$z$ error distribution for weak lensing surveys. Using Fisher matrix analysis, we investigate the contributions of various components of the angular power spectra to the constraints of $n_i(z)$ parameters and demonstrate the importance of the cross power spectra therein, especially when catastrophic photo-$z$ errors are present. We further study the feasibility of reconstructing $n_i(z)$ from galaxy angular power spectra using Markov Chain Monte Carlo estimation. Considering an LSST-like survey with $10$ photo-$z$ bins, we find that the underlying redshift distribution can be determined with a fractional precision ($\\sigma(\\theta)/\\theta$ for parameter $\\...
Modeling the economics and market adoption of distributed power generation
International Nuclear Information System (INIS)
After decades of power generating units increasing in size, there is currently a growing focus on distributed generation, power generation close to energy loads. Investments in large-scale units have been driven by economy of scale, but recent technological improvements on small generating plants have made it possible to exploit the benefits of local power generation to a larger extent than previously. Distributed generation can improve power system efficiency because heat can be recovered from thermal units to supply heat and thermally activated cooling, and because small-scale renewables have a promising end-user market. Further benefits of distributed generation include improved reliability, deferral of often controversial and costly grid investments and reduction of grid losses. The new appeal of small-scale power generation means that there is a need for new tools to analyze distributed generation, both from a system perspective and from the perspective of potential developers. In this thesis, the focus is on the value of power generation for end-users. The thesis identifies how an end-user can find optimal distributed generation systems and investment strategies under a variety of economic and regulatory scenarios. The final part of the thesis extends the analysis with a bottom up model of how the economics of distributed generation for a representative set of building types can transfer to technology diffusion in a market. Four separate research papers make up the thesis. In the first paper, Optimal Investment Strategies in Decentralized Renewable Power Generation under Uncertainty, a method for evaluation of investments in renewable power units under price uncertainty is presented. It is assumed the developer has a building with an electricity load and a renewable power resource. The case study compares a set of wind power systems with different capacity and finds that capacity depends on the electricity price and that there under uncertain prices can be a
Distributed renewable power from biomass and other waste fuels
Lyons, Chris
2012-03-01
The world population is continually growing and putting a burden on our fossil fuels. These fossil fuels such as coal, oil and natural gas are used for a variety of critical needs such as power production and transportation. While significant environmental improvements have been made, the uses of these fuels are still causing significant ecological impacts. Coal power production efficiency has not improved over the past thirty years and with relatively cheap petroleum cost, transportation mileage has not improved significantly either. With the demand for these fossil fuels increasing, ultimately price will also have to increase. This presentation will evaluate alternative power production methods using localized distributed generation from biomass, municipal solid waste and other waste sources of organic materials. The presentation will review various gasification processes that produce a synthetic gas that can be utilized as a fuel source in combustion turbines for clean and efficient combined heat and power. This fuel source can produce base load renewable power. In addition tail gases from the production of bio-diesel and methanol fuels can be used to produce renewable power. Being localized can reduce the need for long and costly transmission lines making the production of fuels and power from waste a viable alternative energy source for the future.
Spatial and spectral oxide trap distributions of power MOSFETs
International Nuclear Information System (INIS)
Commercial power MOSFET (A, B and C) oxides have been characterized by irradiation and isochronal annealing. Low dose irradiation (100 krad(SiO2) under positive and negative bias shows a uniform oxide charge trapping for the two unhardened devices and an interfacial oxide trap distribution in the case of the rad-hard device. High dose irradiation (10 Mrad(SiO2) under high negative bias demonstrates the build-up of an electron trapped charge for device A and the conduction at high dose of a parasitic transistor for device B. Irradiation up to 100 krad(SiO2) and isochronal annealing under positive bias is carried out to compare the spectral distribution of oxide traps between device A oxide and reference buried oxides (SIMOX and UNIBOND). Despite a similar trapping behavior, their spectral distributions are different. Device A presents a lower energy distribution than buried oxides. (authors)
Energy Technology Data Exchange (ETDEWEB)
Chacko, M; Aldoohan, S; Sonnad, J; Ahmad, S; Ali, I [University of Oklahoma Health Science Center, Oklahoma City, OK (United States)
2015-06-15
Purpose: To evaluate quantitatively dose distributions from helical, axial and cone-beam CT clinical imaging techniques by measurement using a two-dimensional (2D) diode-array detector. Methods: 2D-dose distributions from selected clinical protocols used for axial, helical and cone-beam CT imaging were measured using a diode-array detector (MapCheck2). The MapCheck2 is composed from solid state diode detectors that are arranged in horizontal and vertical lines with a spacing of 10 mm. A GE-Light-Speed CT-simulator was used to acquire axial and helical CT images and a kV on-board-imager integrated with a Varian TrueBeam-STx machine was used to acquire cone-beam CT (CBCT) images. Results: The dose distributions from axial, helical and cone-beam CT were non-uniform over the region-of-interest with strong spatial and angular dependence. In axial CT, a large dose gradient was measured that decreased from lateral sides to the middle of the phantom due to large superficial dose at the side of the phantom in comparison with larger beam attenuation at the center. The dose decreased at the superior and inferior regions in comparison to the center of the phantom in axial CT. An asymmetry was found between the right-left or superior-inferior sides of the phantom which possibly to angular dependence in the dose distributions. The dose level and distribution varied from one imaging technique into another. For the pelvis technique, axial CT deposited a mean dose of 3.67 cGy, helical CT deposited a mean dose of 1.59 cGy, and CBCT deposited a mean dose of 1.62 cGy. Conclusions: MapCheck2 provides a robust tool to measure directly 2D-dose distributions for CT imaging with high spatial resolution detectors in comparison with ionization chamber that provides a single point measurement or an average dose to the phantom. The dose distributions measured with MapCheck2 consider medium heterogeneity and can represent specific patient dose.
Energy storage system control strategies for power distribution systems
Directory of Open Access Journals (Sweden)
Areewan Kajorndech
2015-03-01
Full Text Available Energy storage systems have been widely employed to attain several benefits, such as reliability improvement, stabilization of power systems connected with renewable energy resources, economic benefits and etc. To achieve the above objectives, the appropriate and effective control strategies for energy storage systems are needed to be developed. This research proposes energy storage system control strategies for power distribution systems equipped with a limited size of energy storage system in order to improve reliability and save energy costs by determining an optimal charging schedule of the energy storage system. Simulation results demonstrate the benefits of energy storage system applications under the different control strategies.
Convex relaxation of Optimal Power Flow in Distribution Feeders with embedded solar power
DEFF Research Database (Denmark)
Hermann, Alexander Niels August; Wu, Qiuwei; Huang, Shaojun;
2016-01-01
There is an increasing interest in using Distributed Energy Resources (DER) directly coupled to end user distribution feeders. This poses an array of challenges because most of today’s distribution feeders are designed for unidirectional power flow. Therefore when installing DERs such as solar pa...... to minimize the global line losses of the feeder. The mathematical model is presented in details. Further, case studies are completed with simulations involving a 15-bus radial distribution system. These simulations are run for 24 hour periods, with actual solar data and demand data....
Multi-Functional Distributed Generation Unit for Power Quality Enhancement
DEFF Research Database (Denmark)
Zeng, Zheng; Yang, Huan; Guerrero, Josep M.;
2015-01-01
A multi-functional distributed generation unit (MFDGU) and its control strategy are proposed in this paper for the purpose of enhancing power quality in low-voltage networks. By using the 3H-bridge converter structure, an MFDGU can be applied in 3-phase 4-wire low-voltage distribution networks...... reference of the MFDGU, which can be easily implemented in three-phase networks. A 15kVA prototype consisting of three full bridge converters has been built and tested. Experimental results show the feasibility of the proposed topology and control strategy....
Power exponential velocity distributions in disordered porous media
Matyka, Maciej; Koza, Zbigniew
2016-01-01
Velocity distribution functions link the micro- and macro-level theories of fluid flow through porous media. Here we study them for the fluid absolute velocity and its longitudinal and lateral components relative to the macroscopic flow direction in a model of a random porous medium. We claim that all distributions follow the power exponential law controlled by an exponent $\\gamma$ and a shift parameter $u_0$ and examine how these parameters depend on the porosity. We find that $\\gamma$ has a universal value $1/2$ at the percolation threshold and grows with the porosity, but never exceeds 2.
Power system distributed oscilation detection based on Synchrophasor data
Ning, Jiawei
Along with increasing demand for electricity, integration of renewable energy and deregulation of power market, power industry is facing unprecedented challenges nowadays. Within the last couple of decades, several serious blackouts have been taking place in United States. As an effective approach to prevent that, power system small signal stability monitoring has been drawing more interests and attentions from researchers. With wide-spread implementation of Synchrophasors around the world in the last decade, power systems real-time online monitoring becomes much more feasible. Comparing with planning study analysis, real-time online monitoring would benefit control room operators immediately and directly. Among all online monitoring methods, Oscillation Modal Analysis (OMA), a modal identification method based on routine measurement data where the input is unmeasured ambient excitation, is a great tool to evaluate and monitor power system small signal stability. Indeed, high sampling Synchrophasor data around power system is fitted perfectly as inputs to OMA. Existing methods in OMA for power systems are all based on centralized algorithms applying at control centers only; however, with rapid growing number of online Synchrophasors the computation burden at control centers is and will be continually exponentially expanded. The increasing computation time at control center compromises the real-time feature of online monitoring. The communication efforts between substation and control center will also be out of reach. Meanwhile, it is difficult or even impossible for centralized algorithms to detect some poorly damped local modes. In order to avert previous shortcomings of centralized OMA methods and embrace the new changes in the power systems, two new distributed oscillation detection methods with two new decentralized structures are presented in this dissertation. Since the new schemes brought substations into the big oscillation detection picture, the proposed
Robust Distributed Power Control in Cognitive Radio Networks
fard, Saeideh Parsaei
2011-01-01
We propose a robust distributed uplink power allocation algorithm for underlay cognitive radio networks (CRNs) with a view to maximizing the total utility of secondary users (SUs) when channel gains from SUs to primary base stations, and interference caused by primary users (PUs) to the SUs' base station are uncertain. In doing so, we utilize the worst-case robust optimization to keep the interference caused by SUs to each primary base station below a given threshold, and satisfy the SUs' quality of service for all realizations of uncertainty. We model each uncertain parameter by a bounded distance between its estimated and exact values, and formulate the robust power allocation problem via protection values for constraints. We demonstrate that the convexity of our problem is preserved, and in some cases converts into a geometric programming problem, which we solve via a distributed algorithm by using Lagrange dual decomposition. To reduce the cost of robustness, defined as the reduction in the total utility ...
Impacts of Electric Vehicle Loads on Power Distribution Systems
DEFF Research Database (Denmark)
Pillai, Jayakrishnan Radhakrishna; Bak-Jensen, Birgitte
2010-01-01
operation. This paper investigates the effects on the key power distribution system parameters like voltages, line drops, system losses etc. by integrating electric vehicles in the range of 0-50% of the cars with different charging capacities. The dump as well as smart charging modes of electric vehicles......Electric vehicles (EVs) are the most promising alternative to replace a significant amount of gasoline vehicles to provide cleaner, CO2 free and climate friendly transportation. On integrating more electric vehicles, the electric utilities must analyse the related impacts on the electricity system...... is applied in this analysis. A typical Danish primary power distribution system is used as a test case for the studies. From the simulation results, not more than 10% of electric vehicles could be integrated in the test system for the dump charging mode. About 40% of electric vehicle loads could...
Using Model Checking for Analyzing Distributed Power Control Problems
Directory of Open Access Journals (Sweden)
Thomas Brihaye
2010-01-01
Full Text Available Model checking (MC is a formal verification technique which has been known and still knows a resounding success in the computer science community. Realizing that the distributed power control (PC problem can be modeled by a timed game between a given transmitter and its environment, the authors wanted to know whether this approach can be applied to distributed PC. It turns out that it can be applied successfully and allows one to analyze realistic scenarios including the case of discrete transmit powers and games with incomplete information. The proposed methodology is as follows. We state some objectives a transmitter-receiver pair would like to reach. The network is modeled by a game where transmitters are considered as timed automata interacting with each other. The objectives are then translated into timed alternating-time temporal logic formulae and MC is exploited to know whether the desired properties are verified and determine a winning strategy.
Strategies for Power/Energy Saving in Distribution Networks
Directory of Open Access Journals (Sweden)
GRIGORAS, G.
2010-05-01
Full Text Available The power/energy losses reduction in distribution systems is an important issue during planning and operation, with important technical and economical implications. Thus, the energy losses minimization implies not only the technical improvement of the network, through its renewal with the introduction of the technological innovations in the equipment and circuit components as well as the optimal planning of the design and development of the network, but also requires the use of the methods and software tools to facilitate the operation process. The paper presents a strategy for power/energy saving which replacement of the 6 kV voltage level with 20 kV voltage level in correlation with the extent of using efficient transformers. In this line, different urban distribution networks were analyzed using fuzzy techniques.
Power-law distribution in Japanese racetrack betting
Ichinomiya, T
2006-01-01
Gambling is one of the basic economic activities that humans indulge in. An investigation of gambling activities provides deep insights into the economic actions of people and sheds lights on the study of econophysics. In this paper we present an analysis of the distribution of the final odds of the races organized by the Japan Racing Association. The distribution of the final odds $P_o(x)$ indicates a clear power law $P_o(x)\\propto 1/x$, where $x$ represents the final odds. This power law can be explained on the basis of the assumption that that every bettor bets his money on the horse that appears to be the strongest in a race.
Integration of distributed generation in the power system
Bollen, Math H J
2011-01-01
"The integration of new sources of energy like wind power, solar-power, small-scale generation, or combined heat and power in the power grid is something that impacts a lot of stakeholders: network companies (both distribution and transmission), the owners and operators of the DG units, other end-users of the power grid (including normal consumers like you and me) and not in the least policy makers and regulators. There is a lot of misunderstanding about the impact of DG on the power grid, with one side (including mainly some but certainly not all, network companies) claiming that the lights will go out soon, whereas the other side (including some DG operators and large parks of the general public) claiming that there is nothing to worry about and that it's all a conspiracy of the large production companies that want to protect their own interests and keep the electricity price high. The authors are of the strong opinion that this is NOT the way one should approach such an important subject as the integration...
Electric Power Quality and Distributed Generation in Cuba
Directory of Open Access Journals (Sweden)
Miguel Castro Fernández
2010-10-01
Full Text Available Diesel engine generator (RM is one of the most used technologies on distributed generation (DG. The presence of RM, no manner its operation form need an analysis about differents problems: one of them is related with power quality (PQ. First results obained inside one study directed to obtain answers about differents perturbations for the RM presence like shortcircuit and voltage variation on RM termianls and rejected charge are presented in this paper.
Distributed Frequency Control in Power Grids Under Limited Communication
Parandehgheibi, Marzieh; Turitsyn, Konstantin; Modiano, Eytan
2016-01-01
In this paper, we analyze the impact of communication failures on the performance of optimal distributed frequency control. We consider a consensus-based control scheme, and show that it does not converge to the optimal solution when the communication network is disconnected. We propose a new control scheme that uses the dynamics of power grid to replicate the information not received from the communication network, and prove that it achieves the optimal solution under any single communicatio...
Full power operation after long time with low power operation
International Nuclear Information System (INIS)
It is simulated Angra-1 nuclear power plant which is operating slight power during long period followed by full power operation. It was calculated the axial power distribution utilizing the 1D model of CITATION code modified by FURNAS. (M.C.K.)
Technique applied in electrical power distribution for Satellite Launch Vehicle
Directory of Open Access Journals (Sweden)
João Maurício Rosário
2010-09-01
Full Text Available The Satellite Launch Vehicle electrical network, which is currently being developed in Brazil, is sub-divided for analysis in the following parts: Service Electrical Network, Controlling Electrical Network, Safety Electrical Network and Telemetry Electrical Network. During the pre-launching and launching phases, these electrical networks are associated electrically and mechanically to the structure of the vehicle. In order to succeed in the integration of these electrical networks it is necessary to employ techniques of electrical power distribution, which are proper to Launch Vehicle systems. This work presents the most important techniques to be considered in the characterization of the electrical power supply applied to Launch Vehicle systems. Such techniques are primarily designed to allow the electrical networks, when submitted to the single-phase fault to ground, to be able of keeping the power supply to the loads.
The place of solar power: an economic analysis of concentrated and distributed solar power
Banoni Vanessa; Arnone Aldo; Fondeur Maria; Hodge Annabel; Offner J.; Phillips Jordan K
2012-01-01
Abstract Background This paper examines the cost and benefits, both financial and environmental, of two leading forms of solar power generation, grid-tied photovoltaic cells and Dish Stirling Systems, using conventional carbon-based fuel as a benchmark. Methods First we define how these solar technologies will be implemented and why. Then we delineate a model city and its characteristics, which will be used to test the two methods of solar-powered electric distribution. Then we set the constr...
Power distribution monitoring and control in the RBMK type reactors
International Nuclear Information System (INIS)
Considered are the structures of monitoring and control systems for the RBMK-1000 reactor including three main systems with high independence: the control and safety system (CSS); the system for physical control of energy distribution (SPCED) as well as the Scala system for centralized control (SCC). Main functions and peculiarities of each system are discussed. Main attention is paid to new structural solutions and new equipment components used in these systems. Described are the RBMK operation software and routine of energy distribution control in it. It is noted that the set of reactor control and monitoring systems has a hierarchical structure, the first level of which includes analog systems (CSS and SPCED) normalizing and transmitting detector signals to the systems of the second level based on computers and realizing computer data processing, data representation to the operator, automatic (through CSS) control for energy distribution, diagnostics of equipment condition and local safety with provision for existing reserves with respect to crisis and thermal loading of fuel assemblies. The third level includes a power computer carrying out complex physical and optimization calculations and providing interconnections with the external computer of power system. A typical feature of the complex is the provision of local automatic safety of the reactor from erroneous withdrawal of any control rod. The complex is designed for complete automatization of energy distribution control in reactor in steady and transient operation conditions
Kwak, Kiho; Kwak, Dongmin; Yoon, Joohong
2015-08-01
A design of an Instantaneous High Power Supply System (IHPSS) with a power distribution management (PDM) for portable military devices is newly addressed. The system includes a power board and a hybrid battery that can not only supply instantaneous high power but also maintain stable operation at critical low temperature (-30 °C). The power leakage and battery overcharge are effectively prevented by the optimal PDM. The performance of the proposed system under the required pulse loads and the operating conditions of a Korean Advanced Combat Rifle employed in the battlefield is modeled with simulations and verified experimentally. The system with the IHPSS charged the fuse setter with 1.7 times higher voltage (8.6 V) than the one without (5.4 V) under the pulse discharging rate (1 A at 0.5 duty, 1 ms) for 500 ms.
Enhanced power quality based single phase photovoltaic distributed generation system
Panda, Aurobinda; Pathak, M. K.; Srivastava, S. P.
2016-08-01
This article presents a novel control strategy for a 1-ϕ 2-level grid-tie photovoltaic (PV) inverter to enhance the power quality (PQ) of a PV distributed generation (PVDG) system. The objective is to obtain the maximum benefits from the grid-tie PV inverter by introducing current harmonics as well as reactive power compensation schemes in its control strategy, thereby controlling the PV inverter to achieve multiple functions in the PVDG system such as: (1) active power flow control between the PV inverter and the grid, (2) reactive power compensation, and (3) grid current harmonics compensation. A PQ enhancement controller (PQEC) has been designed to achieve the aforementioned objectives. The issue of underutilisation of the PV inverter in nighttime has also been addressed in this article and for the optimal use of the system; the PV inverter is used as a shunt active power filter in nighttime. A prototype model of the proposed system is developed in the laboratory, to validate the effectiveness of the control scheme, and is tested with the help of the dSPACE DS1104 platform.
Directory of Open Access Journals (Sweden)
Rachid DEHINI
2010-12-01
Full Text Available In this paper, the main aim is to confront the performance of shunt active power filter (SAPF and the shunt hybrid active power filter (SHAPF to achieve flexibility and reliability of the filter devices. Both of the two devices used the classical proportional-integral controller for pulse generation to trigger the inventers MOSFETs. In the adopted hybrid active filter there is a passive power filter with high power rating to filter the low order harmonies and one active filter with low power rating to filter the other high order harmonies. In order to investigate the effectiveness of (SHAPF, the studies have been accomplished using simulation with the MATLAB-SIMULINK. The results show That (SHAPF is more effective than (SAPF, and has lower cost.
Electric power transmission and distribution in Germany - an NTPA success
International Nuclear Information System (INIS)
The German Energy Law of April 1998 opened 100 percent of the German electricity market to competition without any transition phase. Over four years later, the degree of market opening is still ahead of that in many other European countries. Transition phases elsewhere have been dominated by the need to develop detailed rules not only for the functioning of the power markets - e.g. in power exchanges - but also for the transmission and distribution system operators and for the data exchange between market participants. Especially the data exchange needs for the handling of household customers switching suppliers has been a challenge in all the countries that have opened the household customer market. But also the network access fees on both transmission and distribution level are still being debated in many countries. The German governments have so far chosen to let the network operators develop the access rules, pricing rules and data exchange standards in intense - and intensely observed - negotiations with the network users. Important outcomes of such negotiations include the well-known Associations' Agreements, GridCode, DistributionCode, MeteringCode as well as the government's Best Practice Recommendations on data exchange standards for the switching between suppliers. One important advantage of this negotiation-based rather than regulatory approach is its speed and flexibility. For example, the Associations' Agreement on network access fees is now valid in its third version, and each successive version included important learning from the experience of both network operators and network users with the previous agreement. This paper will summarise the legal framework of the liberalised power market in Germany and focus on the current state of pricing rules in the Associations' Agreement, of well advanced comparisons run by VDN, of the network access fees of hundreds of distribution system operators including specific data on structural differences of their
Power Distribution Analysis for the ORNL High Flux Isotope Reactor Critical Experiment 3
International Nuclear Information System (INIS)
. Power distributions were obtained for clean core (no poison in moderator and symmetrical rod position at 44.536 cm withdrawn with respect to the core axial midplane) and fully poisoned moderator (1.35 grams of boron per liter in moderator and rods fully withdrawn) conditions. The observed deviations between the experimental and calculated values for both conditions were within the reported experimental uncertainties except for some foils located on the top and bottom edges of the fuel plates.
Anisotropic Azimuthal Power and Temperature distribution on FuelRod. Impact on Hydride Distribution
Energy Technology Data Exchange (ETDEWEB)
Motta, Arthur [Pennsylvania State Univ., State College, PA (United States); Ivanov, Kostadin [Pennsylvania State Univ., State College, PA (United States); Arramova, Maria [Pennsylvania State Univ., State College, PA (United States); Hales, Jason [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2015-04-29
The degradation of the zirconium cladding may limit nuclear fuel performance. In the high temperature environment of a reactor, the zirconium in the cladding corrodes, releasing hydrogen in the process. Some of this hydrogen is absorbed by the cladding in a highly inhomogeneous manner. The distribution of the absorbed hydrogen is extremely sensitive to temperature and stress concentration gradients. The absorbed hydrogen tends to concentrate near lower temperatures. This hydrogen absorption and hydride formation can cause cladding failure. This project set out to improve the hydrogen distribution prediction capabilities of the BISON fuel performance code. The project was split into two primary sections, first was the use of a high fidelity multi-physics coupling to accurately predict temperature gradients as a function of r, θ , and z, and the second was to use experimental data to create an analytical hydrogen precipitation model. The Penn State version of thermal hydraulics code COBRA-TF (CTF) was successfully coupled to the DeCART neutronics code. This coupled system was verified by testing and validated by comparison to FRAPCON data. The hydrogen diffusion and precipitation experiments successfully calculated the heat of transport and precipitation rate constant values to be used within the hydrogen model in BISON. These values can only be determined experimentally. These values were successfully implemented in precipitation, diffusion and dissolution kernels that were implemented in the BISON code. The coupled output was fed into BISON models and the hydrogen and hydride distributions behaved as expected. Simulations were conducted in the radial, axial and azimuthal directions to showcase the full capabilities of the hydrogen model.
Axial Vircator for Electronic Warfare Applications
L. Drazan; R. Vrana
2009-01-01
This paper deals with a high power microwave generator with virtual cathode – vircator in axial release for electronic warfare applications. The classification of directed energy weapons microwave (DEWM) is introduced together with basic block diagrams of a particular class of DEWM. In the paper, methods for designing vircator pulsed power supply, axial vircator structure, measurement methods and experimental results are presented. The vircator in electromagnetic ammunition is powered b...
Eriksson, Stefanie; Lasič, Samo; Nilsson, Markus; Westin, Carl-Fredrik; Topgaard, Daniel
2015-01-01
We introduce a nuclear magnetic resonance method for quantifying the shape of axially symmetric microscopic diffusion tensors in terms of a new diffusion anisotropy metric, DΔ, which has unique values for oblate, spherical, and prolate tensor shapes. The pulse sequence includes a series of equal-amplitude magnetic field gradient pulse pairs, the directions of which are tailored to give an axially symmetric diffusion-encoding tensor b with variable anisotropy bΔ. Averaging of data acquired for...
Time series power flow analysis for distribution connected PV generation.
Energy Technology Data Exchange (ETDEWEB)
Broderick, Robert Joseph; Quiroz, Jimmy Edward; Ellis, Abraham; Reno, Matthew J.; Smith, Jeff; Dugan, Roger
2013-01-01
Distributed photovoltaic (PV) projects must go through an interconnection study process before connecting to the distribution grid. These studies are intended to identify the likely impacts and mitigation alternatives. In the majority of the cases, system impacts can be ruled out or mitigation can be identified without an involved study, through a screening process or a simple supplemental review study. For some proposed projects, expensive and time-consuming interconnection studies are required. The challenges to performing the studies are twofold. First, every study scenario is potentially unique, as the studies are often highly specific to the amount of PV generation capacity that varies greatly from feeder to feeder and is often unevenly distributed along the same feeder. This can cause location-specific impacts and mitigations. The second challenge is the inherent variability in PV power output which can interact with feeder operation in complex ways, by affecting the operation of voltage regulation and protection devices. The typical simulation tools and methods in use today for distribution system planning are often not adequate to accurately assess these potential impacts. This report demonstrates how quasi-static time series (QSTS) simulation and high time-resolution data can be used to assess the potential impacts in a more comprehensive manner. The QSTS simulations are applied to a set of sample feeders with high PV deployment to illustrate the usefulness of the approach. The report describes methods that can help determine how PV affects distribution system operations. The simulation results are focused on enhancing the understanding of the underlying technical issues. The examples also highlight the steps needed to perform QSTS simulation and describe the data needed to drive the simulations. The goal of this report is to make the methodology of time series power flow analysis readily accessible to utilities and others responsible for evaluating
Distribution of power output when establishing a breakaway in cycling.
Abbiss, Chris R; Menaspà, Paolo; Villerius, Vincent; Martin, David T
2013-07-01
A number of laboratory-based performance tests have been designed to mimic the dynamic and stochastic nature of road cycling. However, the distribution of power output and thus physical demands of high-intensity surges performed to establish a breakaway during actual competitive road cycling are unclear. Review of data from professional road-cycling events has indicated that numerous short-duration (5-15 s), high-intensity (~9.5-14 W/kg) surges are typically observed in the 5-10 min before athletes' establishing a breakaway (ie, riding away from a group of cyclists). After this initial high-intensity effort, power output declined but remained high (~450-500 W) for a further 30 s to 5 min, depending on race dynamics (ie, the response of the chase group). Due to the significant influence competitors have on pacing strategies, it is difficult for laboratory-based performance tests to precisely replicate this aspect of mass-start competitive road cycling. Further research examining the distribution of power output during competitive road racing is needed to refine laboratory-based simulated stochastic performance trials and better understand the factors important to the success of a breakaway.
Garanina, O S
2016-01-01
A multi-parametric family of stretch exponential distributions with various power law tails is introduced and is shown to describe adequately the empirical distributions of scientific citation of individual authors. The four-parametric families are characterized by a normalization coefficient in the exponential part, the power exponent in the power-law asymptotic part, and the coefficient for the transition between the above two parts. The distribution of papers of individual scientist over citations of these papers is studied. Scientists are selected via total number of citations in three ranges: 102-103, 103-104, and 104-105 of total citations. We study these intervals for physicists in ISI Web of Knowledge. The scientists who started their scientific publications after 1980 were taken into consideration only. It is detected that the power coefficient in the stretch exponent starts from one for low-cited authors and has to trend to smaller values for scientists with large number of citation. At the same tim...
Integration of Small Solar tower Systems into Distributed Power Islands
Energy Technology Data Exchange (ETDEWEB)
Romero, M.; Marcos, M. J.; Tellez, F. M.; Blanco, M.; Fernandez, V.; Baonza, F.; Berger, S. [Ciemat, Madrid (Spain)
2000-07-01
One of the short-term priorities for renewable energies in Europe is their integration for local power supply into communities and energy islands (blocks of buildings, new neighborhoods in residential areas, shopping centers, hospitals, recreational areas, eco-paks, small rural areas or isolated ones such as islands or mountain communities). Following this strategy, the integration of small tower fields into so-called MIUS (Modular Integrated Utility Systems) is proposed. This application strongly influences field concepts leadings to modular multi-tower systems able to more closely track demand, meet reliability requirements with fewer megawatts of installed power and spread construction costs over time after output has begum. In addition, integration into single-cycle high-efficiency gas turbines plus waste-heat applications clearly increments the solar share. The chief questions are whether solar towers can be redesigned for such distributed markets and the keys to their feasibility. This paper includes the design and performance analysis of a 1.36-MW plant and integration in the MIUS system, as well as the expected cost of electricity and a sensitivity analysis of the small tower plant's performance with design parameters like heliostat configuration and tower height. A practical application is analyzed for a shopping center with 85% power demand during day-time by using a hybrid solar tower and a gas turbine producing electricity and waste heat for hot water and heating and cooling of spaces. The operation mode proposed is covering night demand with power from the grid and solar-gas power island mode during 14 hours daytime with a maximum power production of 1.36 MW. (Author) 26 refs.
Electrical power transmission and distribution aging and life extension techniques
Chudnovsky, Bella H
2012-01-01
""The focus of this unique reference book is four critical areas in the manufacturing of power distribution components. These areas are plating, lubrication, insulator failure, and maintenance. ... The many SEM images, x-ray studies, photos, and tabular data make for a very convenient reference source for diagnosing plating problems. ... Examples often help to drive home a point, and many case studies illustrating the various failure modes described throughout the book are included. These could prove to be an invaluable source of information when trying to diagnose unknown field failures. ...
Impact Study: Photo-voltaic Distributed Generation on Power System
Sahoo, Smrutirekha
2016-01-01
The grid-connected photo-voltaic (PV) system is one of the most promising renewable energy solutions which offers many benefits to both the end user and the utility network and thus it has gained the popularity over the last few decades. However, due to the very nature of its invariability and weather dependencies, the large scale integration of this type of distributed generation has created challenges for the network operator while maintaining the quality of the power supply and also for re...
Using Model Checking for Analyzing Distributed Power Control Problems
DEFF Research Database (Denmark)
Brihaye, Thomas; Jungers, Marc; Lasaulce, Samson;
2010-01-01
Model checking (MC) is a formal verification technique which has been known and still knows a resounding success in the computer science community. Realizing that the distributed power control ( PC) problem can be modeled by a timed game between a given transmitter and its environment, the authors...... objectives a transmitter-receiver pair would like to reach. The network is modeled by a game where transmitters are considered as timed automata interacting with each other. The objectives are then translated into timed alternating-time temporal logic formulae and MC is exploited to know whether the desired...
Directory of Open Access Journals (Sweden)
F. Gharedaghi
2012-03-01
Full Text Available The large number of decision variables of long-term planning problem for improving the distribution system causes lots of complexities. The optimum allocation of Distributed Generation (DG sources and determining their capacity in the deregulated electric market is a key way for capacity expansion of the distribution firm. In this study, a new approach is presented to determination the optimum location and capacity of DG sources in the deregulated electric market through the net present value analysis using an optimization model. This model aims to minimize the investment cost of the distribution firm, utility cost and the losses cost considering the anticipated load peak value. Considering the power market price anticipation to be indefinite, the proposed method is based on laying out the genetic algorithm and a fuzzy model to the power market price and the capacity expansion design of the distribution system during different time intervals is proposed along with two static and semi-dynamic methods. The efficiency of the proposed approach is well shown applying it to a sample network.
Heavy metals distribution in fly ash from gangue power plant
Institute of Scientific and Technical Information of China (English)
ZHOU Guang-zhu; WANG Cui-zhen; HAN Zuo-zhen; YANG Hai-feng; WAN Rui
2007-01-01
To make assessment on its environmental security,fly ash samples were collected from the gangue power plant.Total content of heavy metals in sieved fly ash were analytically determined.We also carried out Tessier extractive experiments to check the chemical species of heavy metals.Experiment results show that the content of Cu,Zn,Pb and Cd ascend when particle size is smaller.Cu,Zn,Pb and Cd obviously enrich in particulate fly ash.The chemical species of heavy metal distribution ranking sequence generally is residual＞organic combinative＞Fe-Mn oxide combinative＞carbonate combinative＞ion-exchangeable.Lead's amiable-move species were high in proportion,amounted to 35%.Total content of Cadmium is at low level.but its ion-exchangeable species is relatively high in proportion.Nickel and zinc is mainly distributed in residue.CU is mainly distributed in residue and Organic combinative form.The content of manganese is relatively high in fly ash,and the carbonate combinative iron-manganese oxide combinative species are main chemical form.Cr is mainly distributed in residue.and its other chemical species are at low level.Compared with the soil background value of study area and Shandong Province,the content of Cu,Ni,Zn,Mn and Cr in fly ash of gangue power plant is lower.While contents of Pb and Cd were higher than background value,and amiable-move species is relatively high in proportion.They are more apt to cause heavy metal pollution.
An Efficient Distributed Power Control in Cognitive Radio Networks
Directory of Open Access Journals (Sweden)
Mohammad Hossein Faridi
2016-01-01
Full Text Available In cognitive radio networks, when primary users (PUs do not use a shared frequency band, secondary users (SUs are allowed to use that frequency band. However, when SU using frequency band and reclaiming PU also wants to use this band, there are two solutions: SU jumps to another existing spectrum band or stays in the same frequency band and changes its power so that interference in the reclaiming PUs does not exceed a threshold. Since the first solution interrupts the SUs' work, the second solution is more appropriate. Therefore, power control in cognitive networks is absolutely significant which should receive more attention. In the previous work (TPC-CBS [2], TPC algorithm has been used for power control. The drawback of this algorithm is fixed target SIRs. In other words, while using this algorithm, all the users having enough sources or extra sources reach the same target SIR, which is not desirable. Therefore, in this paper, we are going to solve it by means of the proposed algorithm called "An Efficient Distributed Power Control Algorithm for Cognitive Networks (EDPC". By the proposed algorithm, when a user has a bad channel, its SIR sets to the minimum target SIR and, when it has a good channel, its SIR will be more than the minimum value. Moreover, by means of fuzzy logic systems (FLS, the value of interference on reclaiming PU caused by SUs is checked in each iteration and power level of SUs is decreased if this value exceeds a threshold. Simulation results show that using our proposed algorithm not only allows SUs and PUs use frequency band simultaneously, but also enhances throughput significantly in comparison with the previous approaches (TPC-CBS.
Directory of Open Access Journals (Sweden)
Bahman Bahmanifirouzi
2012-03-01
Full Text Available This paper presents a new Fuzzy Adaptive Modified Particle Swarm Optimization algorithm (FAMPSO for the placement of Fuel Cell Power Plants (FCPPs in distribution systems. FCPPs, as Distributed Generation (DG units, can be considered as Combined sources of Heat, Power, and Hydrogen (CHPH. CHPH operation of FCPPs can improve overall system efficiency, as well as produce hydrogen which can be stored for the future use of FCPPs or can be sold for profit. The objective functions investigated are minimizing the operating costs of electrical energy generation of distribution substations and FCPPs, minimizing the voltage deviation and minimizing the total emission. In this regard, this paper just considers the placement of CHPH FCPPs while investment cost of devices is not considered. Considering the fact that the objectives are different, non-commensurable and nonlinear, it is difficult to solve the problem using conventional approaches that may optimize a single objective. Moreover, the placement of FCPPs in distribution systems is a mixed integer problem. Therefore, this paper uses the FAMPSO algorithm to overcome these problems. For solving the proposed multi-objective problem, this paper utilizes the Pareto Optimality idea to obtain a set of solution in the multi-objective problem instead of only one. Also, a fuzzy system is used to tune parameters of FAMPSO algorithm such as inertia weight. The efficacy of the proposed approach is validated on a 69-bus distribution system.
Application of PowerBuilder User Objects in Developing Distributed Programs
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
User Objects are the basement in developing distributed PowerBuilder applications. There are two kinds of PowerBuilder objects: visual objects and non-visual objects. Usually we use non-visual objects to perform the PowerBuilder distriuted application. This paper introduces the method of developing PowerBuilder distributed application program,mainly discusses the application of nonvisual objects when developing PowerBuilder distributed application programs.
Voltage multi-stability in distribution grids with power flow reversal
Nguyen, Hung D.; Turitsyn, Konstantin
2014-01-01
High levels of penetration of distributed generation and aggressive reactive power compensation with modern power electronics may result in the reversal of active and reactive power flows in future distribution grids. The voltage stability of these operating conditions may be very different from the more traditional power consumption regime. We study the stability characteristics of distribution networks with reversed power flow. After introducing a universal algebraic approach to characteriz...
Energy Technology Data Exchange (ETDEWEB)
NONE
1999-01-10
Aiming at earlier restoration of failures and further improvement of efficiency in control of power distribution system operation, Okinawa Electric Power and Fuji Electric have been proceeding with review of the specifications and functions of a power distribution automating system. Its partial operation has now begun by using a remote control system consisting mainly of remotely controlled operation of switches. The major features of the system may be summarized as follows: (1) it has two-console configuration capable of simultaneous parallel operation and continuation of operation even at server shutdown by using a man-machine workstation; (2) a simplified mapping system is adopted for indication of a distribution system chart, incorporating features of both of the mapping system and the skeleton system; (3) a simplified system operating function is employed, in which procedures of load switching and returning operations are prepared and executed automatically without a need of registering an event name; and (4) a system to memorize operation procedures for facility data maintenance is used to respond flexibly to sequence exchange of construction names and postponement of a construction. (NEDO)
DEFF Research Database (Denmark)
Savaghebi, Mehdi; Hashempour, Mohammad M.; Guerrero, Josep M.
2014-01-01
includes two control levels: primary control and secondary control. Primary control consists of power controllers, selective virtual impedance loops and proportional-resonant (PR) voltage/current controllers. Secondary control manages the compensation of voltage harmonic distortion of sensitive load bus......This paper addresses the coordinated control of distributed generators (DGs) inverters and active power filters (APFs) to compensate voltage harmonics in microgrids. For this, a hierarchical control system is proposed to mitigate voltage harmonic distortion. The hierarchical control structure...... (SLB). Compensation of SLB harmonics by control of DGs may cause excessive voltage harmonics at the terminal of one or more of DGs interface inverters and/or overloading of the inverters. After occurrence of each of these cases, active power filter (APF) participates in harmonic compensation...
Retinal ganglion cell distribution and spatial resolving power in elasmobranchs.
Lisney, Thomas J; Collin, Shaun P
2008-01-01
The total number, distribution and peak density of presumed retinal ganglion cells was assessed in 10 species of elasmobranch (nine species of shark and one species of batoid) using counts of Nissl-stained cells in retinal wholemounts. The species sampled include a number of active, predatory benthopelagic and pelagic sharks that are found in a variety of coastal and oceanic habitats and represent elasmobranch groups for which information of this nature is currently lacking. The topographic distribution of cells was heterogeneous in all species. Two benthic species, the shark Chiloscyllium punctatum and the batoid Taeniura lymma, have a dorsal or dorso-central horizontal streak of increased cell density, whereas the majority of the benthopelagic and pelagic sharks examined exhibit a more concentric pattern of increasing cell density, culminating in a central area centralis of higher cell density located close to the optic nerve head. The exception is the shark Alopias superciliosus, which possesses a ventral horizontal streak. Variation in retinal ganglion cell topography appears to be related to the visual demands of different habitats and lifestyles, as well as the positioning of the eyes in the head. The upper limits of spatial resolving power were calculated for all 10 species, using peak ganglion cell densities and estimates of focal length taken from cryo-sectioned eyes in combination with information from the literature. Spatial resolving power ranged from 2.02 to 10.56 cycles deg(-1), which is in accordance with previous studies. Species with a lower spatial resolving power tend to be benthic and/or coastal species that feed on benthic invertebrates and fishes. Active, benthopelagic and pelagic species from more oceanic habitats which feed on larger, more active prey, possess a higher resolving power. Additionally, ganglion cells in a juvenile of C. punctatum, were retrogradely-labeled from the optic nerve with biotinylated dextran amine (BDA). A comparison
Leadership in Mammalian Societies: Emergence, Distribution, Power, and Payoff.
Smith, Jennifer E; Gavrilets, Sergey; Mulder, Monique Borgerhoff; Hooper, Paul L; El Mouden, Claire; Nettle, Daniel; Hauert, Christoph; Hill, Kim; Perry, Susan; Pusey, Anne E; van Vugt, Mark; Smith, Eric Alden
2016-01-01
Leadership is an active area of research in both the biological and social sciences. This review provides a transdisciplinary synthesis of biological and social-science views of leadership from an evolutionary perspective, and examines patterns of leadership in a set of small-scale human and non-human mammalian societies. We review empirical and theoretical work on leadership in four domains: movement, food acquisition, within-group conflict mediation, and between-group interactions. We categorize patterns of variation in leadership in five dimensions: distribution (across individuals), emergence (achieved versus inherited), power, relative payoff to leadership, and generality (across domains). We find that human leadership exhibits commonalities with and differences from the broader mammalian pattern, raising interesting theoretical and empirical issues. PMID:26552515
Unbalanced Load Simulation of Electronic Power Transformer in Distribution System
Institute of Scientific and Technical Information of China (English)
Wang Dan; Mao Chengxiong; Lu Jiming; Fan Shu; Cao Jiewei; Wang Ben
2006-01-01
A control scheme of electronic power transformer (EPT) in a three-phase four-wire distribution system, which included an input section, an isolating section and an output section, was researched under unbalanced loads. The simple and appropriate control scheme was developed through analyzing the system requirements of the primary side and the load requirements of the secondary side. In the input section, a dual-loop control in synchronous rotating d-q coordinates was introduced, and in the output section, a dual-loop control based on instantaneous output voltage wasused. Load characteristics of EPT were investigated by using Matlab/Simulink software. Simulation results showed that, with the proposed control scheme, the EPT has good performances and the sinusoidal input current and constant output voltage can be realized under both balanced and unbalanced loads.
Models and Methods for Urban Power Distribution Network Planning
Institute of Scientific and Technical Information of China (English)
余贻鑫; 王成山; 葛少云; 肖俊; 严雪飞; 黄纯华
2004-01-01
The models, methods and their application experiences of a practical GIS(geographic information system)-based computer decision-making support system of urban power distribution network planning with seven subsystems, termed CNP, are described. In each subsystem there is at least one or one set of practical mathematical methobs. Some new models and mathematical methods have been introduced. In the development of GNP the idea of cognitive system engineering has been insisted on, which claims that human and computer intelligence should be combined together to solve the complex engineering problems cooperatively. Practical applications have shown that not only the optimal plan can be automatically reached with many complicated factors considered, but also the computation,analysis and graphic drawing burden can be released considerably.
Nonperturbative features of the axial current
Kopeliovich, B Z; Siddikov, M
2013-01-01
In this paper we study the nonperturbative structure of the axial current and evaluate the two-point distribution amplitudes $\\int d\\xi\\, e^{-iq...\\xi}$ in the framework of the instanton vacuum model in the leading order in $\\mathcal{O}(N_{c})$. We perform a direct numerical test of the relations between the axial current and the pion distribution amplitudes, imposed by PCAC, and found excellent agreement.
Power law distributions of patents as indicators of innovation.
Directory of Open Access Journals (Sweden)
Dion R J O'Neale
Full Text Available The total number of patents produced by a country (or the number of patents produced per capita is often used as an indicator for innovation. Here we present evidence that the distribution of patents amongst applicants within many countries is well-described by power laws with exponents that vary between 1.66 (Japan and 2.37 (Poland. We suggest that this exponent is a useful new metric for studying innovation. Using simulations based on simple preferential attachment-type rules that generate power laws, we find we can explain some of the variation in exponents between countries, with countries that have larger numbers of patents per applicant generally exhibiting smaller exponents in both the simulated and actual data. Similarly we find that the exponents for most countries are inversely correlated with other indicators of innovation, such as research and development intensity or the ubiquity of export baskets. This suggests that in more advanced economies, which tend to have smaller values of the exponent, a greater proportion of the total number of patents are filed by large companies than in less advanced countries.
Power Law Distributions of Patents as Indicators of Innovation
O'Neale, D R J
2012-01-01
The total number of patents produced by a country (or the number of patents produced per capita) is often used as an indicator for innovation. Here we present evidence that the distribution of patents amongst applicants within many OECD countries is well-described by power laws with exponents that vary between 1.66 (Japan) and 2.37 (Poland). Using simulations based on simple preferential attachment-type rules that generate power laws, we find we can explain some of the variation in exponents between countries, with countries that have larger numbers of patents per applicant generally exhibiting smaller exponents in both the simulated and actual data. Similarly we find that the exponents for most countries are inversely correlated with other indicators of innovation, such as R&D intensity or the ubiquity of export baskets. This suggests that in more advanced economies, which tend to have smaller values of the exponent, a greater proportion of the total number of patents are filed by large companies than in...
Optimum Distribution Generator Placement in Power Distribution System Using Ant Colony Algorithm
Directory of Open Access Journals (Sweden)
Mehdi Mahdavi
2009-03-01
Full Text Available The recent development in renewable energy systems and the high demand for having clean and low cost energy sources encourage people to use distributed generator (DG systems. Proper addition and placement of DG units can increase reliability and reduce the loss and production cost. In this paper using Ant Colony method, we developed an optimum placing scheme for DGs. The proposed method is tested on an IEEE 34-shinhe system. Results show that if DGs are able to generate active power, their effectiveness will increase.
Directory of Open Access Journals (Sweden)
Yin Yin Winn
2014-10-01
Full Text Available Due to the rapid development in automation system, control and monitoring are necessary for any modern system. DCS provides this control and monitoring for industrial automation. The system is designed and constructed Distributed Control System (DCS based power distribution in university campus. The research has constructed hardware and utilized Microsoft Visual Basic software in software environment using a communication network and embedded controllers. All hardware and software components have been developed and integrated together. Data exchange mechanism, USB cable has been developed between the host computer and the embedded controllers that function in two way data exchanges between the two. This system uses PIC 18F4550 microcontroller to collect electrical parameters of devices in each departments. The Graphical User Interface (GUI uses Visual Basic Software under Microsoft Visual Basic 2010 express to achieve data real-time display and status display for the loads.
Chakraborty, Sudipta; Kramer, William E
2013-01-01
While most books approach power electronics and renewable energy as two separate subjects, Power Electronics for Renewable and Distributed Energy Systems takes an integrative approach; discussing power electronic converters topologies, controls and integration that are specific to the renewable and distributed energy system applications. An overview of power electronic technologies is followed by the introduction of various renewable and distributed energy resources that includes photovoltaics, wind, small hydroelectric, fuel cells, microturbines and variable speed generation. Energy storage s
Validating MCNP for LEU Fuel Design via Power Distribution Comparisons
Energy Technology Data Exchange (ETDEWEB)
Primm, Trent [ORNL; Maldonado, G Ivan [ORNL; Chandler, David [ORNL
2008-11-01
The mission of the Reduced Enrichment for Research and Test Reactors (RERTR) Program is to minimize and, to the extent possible, eliminate the use of highly enriched uranium (HEU) in civilian nuclear applications by working to convert research and test reactors, as well as radioisotope production processes, to low enriched uranium (LEU) fuel and targets. Oak Ridge National Lab (ORNL) is reviewing the design bases and key operating criteria including fuel operating parameters, enrichment-related safety analyses, fuel performance, and fuel fabrication in regard to converting the fuel of the High Flux Isotope Reactor (HFIR) from HEU to LEU. The purpose of this study is to validate Monte Carlo methods currently in use for conversion analyses. The methods have been validated for the prediction of flux values in the reactor target, reflector, and beam tubes, but this study focuses on the prediction of the power density profile in the core. A current 3-D Monte Carlo N-Particle (MCNP) model was modified to replicate the HFIR Critical Experiment 3 (HFIRCE-3) core of 1965. In this experiment, the power profile was determined by counting the gamma activity at selected locations in the core. Foils (chunks of fuel meat and clad) were punched out of the fuel elements in HFIRCE-3 following irradiation and experimental relative power densities were obtained by measuring the activity of these foils and comparing each foil s activity to the activity of a normalizing foil. The current work consisted of calculating corresponding activities by inserting volume tallies into the modified MCNP model to represent the punchings. The average fission density was calculated for each foil location and then normalized to the normalizing foil. Power distributions were obtained for the clean core (no poison in moderator and symmetrical rod position at 17.5 inches) and fully poisoned-moderator (1.35 g B/liter in moderator and rods fully withdrawn) conditions. The observed deviations between the
Directory of Open Access Journals (Sweden)
Abouzar Samimi
2016-01-01
Full Text Available One of the most significant control schemes in optimal operation of distribution networks is Volt/Var control (VVC. Owing to the radial structure of distribution systems and distribution lines with a small X/R ratio, the active power scheduling affects the VVC issue. A Distribution System Operator (DSO procures its active and reactive power requirements from Distributed Generations (DGs along with the wholesale electricity market. This paper proposes a new operational scheduling method based on a joint day-ahead active/reactive power market at the distribution level. To this end, based on the capability curve, a generic reactive power cost model for DGs is developed. The joint active/reactive power dispatch model presented in this paper motivates DGs to actively participate not only in the energy markets, but also in the VVC scheme through a competitive market. The proposed method which will be performed in an offline manner aims to optimally determine (i the scheduled active and reactive power values of generation units; (ii reactive power values of switched capacitor banks; and (iii tap positions of transformers for the next day. The joint active/reactive power dispatch model for daily VVC is modeled in GAMS and solved with the DICOPT solver. Finally, the plausibility of the proposed scheduling framework is examined on a typical 22-bus distribution test network over a 24-h period.
An Effective Distributed Model for Power System Transient Stability Analysis
MUTHU, B. M.; VEILUMUTHU, R.; PONNUSAMY, L.
2011-01-01
The modern power systems consist of many interconnected synchronous generators having different inertia constants, connected with large transmission network and ever increasing demand for power exchange. The size of the power system grows exponentially due to increase in power demand. The data required for various power system applications have been stored in different formats in a heterogeneous environment. The power system applications themselves have been developed and deployed in diff...
Aging Management Guideline for commercial nuclear power plants: Power and distribution transformers
International Nuclear Information System (INIS)
This Aging Management Guideline (AMG) provides recommended methods for effective detection and mitigation of age-related degradation mechanisms in power and distribution transformers important to license renewal in commercial nuclear power plants. The intent of this AMG to assist plant maintenance and operations personnel in maximizing the safe, useful life of these components. It also supports the documentation of effective aging management programs required under the License Renewal Rule 10 CFR Part 54. This AMG is presented in a manner which allows personnel responsible for performance analysis and maintenance to compare their plant-specific aging mechanisms (expected or already experienced) and aging management program activities to the more generic results and recommendations presented herein
Axial Vircator for Electronic Warfare Applications
Directory of Open Access Journals (Sweden)
L. Drazan
2009-12-01
Full Text Available This paper deals with a high power microwave generator with virtual cathode – vircator in axial release for electronic warfare applications. The classification of directed energy weapons microwave (DEWM is introduced together with basic block diagrams of a particular class of DEWM. In the paper, methods for designing vircator pulsed power supply, axial vircator structure, measurement methods and experimental results are presented. The vircator in electromagnetic ammunition is powered by magneto-cumulative generator and in weapons for defense of objects (WDO, it is powered by Marx generator. The possible applications of a vircator in the DEWM area are discussed.
Overvoltages related to distributed generation-power system interconnection transformer
Energy Technology Data Exchange (ETDEWEB)
Zamanillo, G.R.; Gomez, J.C.; Florena, E.F. [Rio Cuarto National University (IPSEP/UNRC), Cordoba (Argentina). Electric Power Systems Protection Institute], Email: jcgomez@ing.unrc.edu.ar
2009-07-01
The energy crisis that experiences the world drives to carry to an extreme, the use of all energy sources which are available. The sources need to be connected to the electric network in their next point, requiring of electric-electronic interfaces. The traditional electric power systems are changing their characteristics, in what concerns to structure, operation and on overvoltage generation. This change is not taking place in coordinated form among the involved sectors. The interconnection of a Distributed Generator (DG) directly with the power system is objectionable and risky. It is required of an interconnection transformer which performs several functions. Rigid specifications do not exist in this respect, for the variety of systems in use in the world, nevertheless there are utilities recommendations. Overvoltages caused by the DG, which arise due to the change of structure of the electric system, are explained. The transformer connection selection, presents positive and negative aspects that impact the utility and the user in a different or many times in an antagonistic way. The phenomenon of balanced and unbalanced ferroresonance overvoltage is studied. This phenomenon can takes place when using DG, either with synchronous or asynchronous generator, and for any type of connection of the transformer. The necessary conditions so that the phenomenon appears are presented. Eight interconnection transformer connection ways were studied. It is concluded that the solutions to reach by means of the employment of the DG, offer technical-economic advantages so much to the utility as to the user. It is also concluded in this work that the more advisable interconnection type is function of the system connection type. (author)
Review of modular power converters solutions for smart transformer in distribution system
DEFF Research Database (Denmark)
Alzola, Rafael Pena; Gohil, Ghanshyamsinh Vijaysinh; Mathe, Laszlo;
2013-01-01
While the use of power electronics based Smart Transformer (ST) is becoming a reality in traction applications, and it has been considered as an interesting option for interfacing different transmission systems, the possibility to use it in distribution systems is still considered futuristic....... Replacing primary distribution transformers with ST can lead to more flexible handling of the distribution feeders, while replacing secondary distribution transformers can allow decoupling of distribution network. This paper reviews different power converter solutions for the ST focusing on modularity...
Mclallin, K. L.; Kofskey, M. G.; Wong, R. Y.
1982-01-01
An experimental evaluation of the aerodynamic performance of the axial flow, variable area stator power turbine stage for the Department of Energy upgraded automotive gas turbine engine was conducted in cold air. The interstage transition duct, the variable area stator, the rotor, and the exit diffuser were included in the evaluation of the turbine stage. The measured total blading efficiency was 0.096 less than the design value of 0.85. Large radial gradients in flow conditions were found at the exit of the interstage duct that adversely affected power turbine performance. Although power turbine efficiency was less than design, the turbine operating line corresponding to the steady state road load power curve was within 0.02 of the maximum available stage efficiency at any given speed.
A Possible Origin of Power-Law Distribution in Stock Markets
Institute of Scientific and Technical Information of China (English)
杨纯斌; 蔡勖
2002-01-01
The origin of the power-law distribution in stock markets is discussed from the point of view of self-organized criticality. An analytical expression for the distribution is given from a simple model consideration. We see that power-law increasing or decreasing distribution functions can have the same origin, depending on the values of the parameters.
Cooperating expert systems for space station power distribution management
International Nuclear Information System (INIS)
In a complex system such as the manned Space Station, it is deemed necessary that many expert systems must perform tasks in a concurrent and cooperative manner. An important question to arise is: what cooperative-task-performing models are appropriate for multiple expert systems to jointly perform tasks. The solution to this question will provide a crucial automation design criteria for the Space Station complex systems architecture. Based on a client/server model for performing tasks, the authors have developed a system that acts as a front-end to support loosely-coupled communications between expert systems running on multiple Symbolics machines. As an example, they use the two ART*-based expert systems to demonstrate the concept of parallel symbolic manipulation for power distribution management and dynamic load planner/scheduler in the simulated Space Station environment. This on-going work will also explore other cooperative-task-performing models as alternatives which can evaluate inter and intra expert system communication mechanisms. It will serve as a testbed and a bench-marking tool for other Space Station expert subsystem communication and information exchange
Reactivity control rod for controlling reactor power distribution
International Nuclear Information System (INIS)
Since a cladding tube is situated at the outer side, it undergoes neutron irradiation in a reactor core and also undergoes compression force due to high pressure of reactor coolants to cause a creep phenomenon, and the diameter is reduced as it is used. Then, neutron absorbing rods as reactivity control rods for controlling the power distribution are constituted with a cladding tube, a spacer tube disposed at the central portion of the cladding tube and a borosilicate glass tube disposed between the cladding tube and the spacer tube. The gap between the borosilicate glass tube and the spacer tube is gradually changed so that the inner diameter of the borosilicate glass is increased as it comes closer to the lower end plug. The time of contact between the cladding tube and the spacer tube in the inside is delayed by the constitution of the borosilicate glass tube disposed in the cladding tube of the neutron absorbing rod as the reactivity control rod thereby capable of extending the integral working life time with no rupture of the cladding tube. (N.H.)
The distribution of absorptive power dissipation in irradiated nanoparticulate system
Li, Jiayu; Yang, Jian; Gu, Xiaobing
2016-10-01
The knowledge of local radiant absorption is important to the nanostructure optimization, it is beneficial to the applications in energy harvesting, optical heating, photocatalysis, etc. In this paper, FDTD model is constructed for the distribution of absorptive power dissipation in irradiated nanoparticulate system. The theoretical model extended from Mie theory is used to examine the FDTD model, the parameters and conditions set for FDTD simulation are confirmed based on the comparison. Then, the influence of Ag nanoparticle on the absorptive properties of nearby TiO2 nanoparticle is investigated by FDTD simulation at the wavelength of 0.25 μm. It is indicated that suitable distance between TiO2 and Ag particles is beneficial to the spectral radiant absorption of TiO2 particle. Considering the agglomeration of nanoparticles and the oxidation at the TiO2-Ag interface, the Ag core coated with Al2O3 shell is suggested, and the simulated results indicated that the shell thickness and the Ag core size need to be optimized for enhancing the radiant absorption of TiO2 particle.
Through flow analysis within axial flow turbomachinery blade rows
Girigoswami, H.
1986-09-01
Using Katsanis' Through Flow Code, inviscid flow through an axial flow compressor rotor blade as well as flow through inlet guide vanes are analyzed and the computed parameters such as meridional velocity distribution, axial velocity distribution along radial lines, and velocity distribution over blade surfaces are presented.
The place of solar power: an economic analysis of concentrated and distributed solar power
Directory of Open Access Journals (Sweden)
Banoni Vanessa
2012-04-01
Full Text Available Abstract Background This paper examines the cost and benefits, both financial and environmental, of two leading forms of solar power generation, grid-tied photovoltaic cells and Dish Stirling Systems, using conventional carbon-based fuel as a benchmark. Methods First we define how these solar technologies will be implemented and why. Then we delineate a model city and its characteristics, which will be used to test the two methods of solar-powered electric distribution. Then we set the constraining assumptions for each technology, which serve as parameters for our calculations. Finally, we calculate the present value of the total cost of conventional energy needed to power our model city and use this as a benchmark when analyzing both solar models’ benefits and costs. Results The preeminent form of distributed electricity generation, grid-tied photovoltaic cells under net-metering, allow individual homeowners a degree of electric self-sufficiency while often turning a profit. However, substantial subsidies are required to make the investment sensible. Meanwhile, large dish Stirling engine installations have a significantly higher potential rate of return, but face a number of pragmatic limitations. Conclusions This paper concludes that both technologies are a sensible investment for consumers, but given that the dish Stirling consumer receives 6.37 dollars per watt while the home photovoltaic system consumer receives between 0.9 and 1.70 dollars per watt, the former appears to be a superior option. Despite the large investment, this paper deduces that it is far more feasible to get few strong investors to develop a solar farm of this magnitude, than to get 150,000 households to install photovoltaic arrays in their roofs. Potential implications of the solar farm construction include an environmental impact given the size of land require for this endeavour. However, the positive aspects, which include a large CO2 emission reduction aggregated
Power Quality Improvement in Distribution System using ANN Based Shunt Active Power Filter
Directory of Open Access Journals (Sweden)
Somlal Jarupula
2015-02-01
Full Text Available This paper focuses on an Artificial Neural Network (ANN controller based Shunt Active Power Filter (SAPF for mitigating the harmonics of the distribution system. To increase the performance of the conventional controller and take advantage of smart controllers, a feed forward-type (trained by a back propagation algorithm ANN-based technique is implemented in shunt active power filters for producing the controlled pulses required for IGBT inverter. The proposed approach mainly work on the principle of capacitor energy to maintain the DC link voltage of a shunt connected filter and thus reduces the transient response time when there is abrupt variation in the load. The entire power system block set model of the proposed scheme has been developed in MATLAB environment. Simulations are carried out by using MATLAB, it is noticed that the %THD is reduced to 2.27% from 29.71% by ANN controlled filter. The simulated experimental results also show that the novel control method is not only easy to be computed and implemented, but also very successful in reducing harmonics.
Near-field angular distributions of high velocity ions for low-power hall thrusters
Sullivan, Regina M.; Yost, Allison; Johnson, Lee K.
2009-01-01
Experimental angular distributions of high-energy primary ions in the near-field region of a small Hall thruster between 50-200 mm downstream of the thruster exit plane at a range of centerline angles have been determined using a highly-collimated, energy-selective diagnostic probe. The measurements reveal a wide angular distribution of ions exiting the thruster channel and the formation of a strong, axially-directed jet of ions along the thruster centerline. Comparisons are made to other exp...
Study on axial offset oscillation for WWER-1000 reactor by using WWER-1000 simulator
International Nuclear Information System (INIS)
In the operation of thermal neutron reactors, it is known that the spatial xenon oscillations arise frequently. The nature of these oscillations is that almost of power concentrate just at a small region in the reactor core volume. The characteristic parameter for the axial power distribution is axial offset. In this subject, the cause of axial offset oscillation and its characteristics are studied. We investigate axial offset oscillation in begin of fuel cycle (BOC) and end of fuel cycle (EOC) of loading 1 enrichment and loading 5 enrichment for WWER-1000 reactor, using WWER-1000 reactor simulation program that was originally developed by IAEA. The results are: (1) the formation of axial offset oscillation is due to periodic deviation from an equilibrium distribution of iodine, xenon and neutron flux density between the upper half and the lower half of the reactor core, when the control group number 1 is inserted into the bottom of reactor core; (2) regarding the same fuel enrichment, in BOC, offset oscillates with larger amplitude and slower damping than in EOC. On the other hand, in higher fuel enrichment, offset oscillates with smaller amplitude and quicker damping than in lower fuel enrichment. (author)
Determination of the axial stiffness of an optical trap with information entropy signals
Zhong, Mincheng; Zhou, Jinhua; Wu, Jianguang; Li, Yinmei
2009-11-01
Optical tweezers has been used to manipulate micro-sized particles for many years, and has been widely used in various applications. The axial trapping stiffness is one of the most important parameters to evaluate the trapping ability of an optical tweezers. In this paper, we calibrated the axial optical stiffnesses for micro-sized polystyrene spheres. When an external force was applied to particle held by an optical trap, the particle was displaced from the trap center by an amount proportional to the applied force. We displaced the particle from the trap center by applying triangular waves of varying velocity, and the varying velocity was obtained by altering the frequency of the triangular waves. In this case the particle has two balance position distributed at two-side of the trap center. The calibration of the axial position was critical to the measurement of axial optical stiffness. In this paper, the axial displacement between the balance position and the trap center was calibrated with image information entropy signals. According to Stokes Law, when the axial displacement of the particle relative to the external force was known, the axial optical stiffness can be measured, and this method was known as viscous drag method. The stiffnesses for a 2μm-diameter at different trapped depth were measured. Typical values for axial optical stiffness of our optical tweezers were between 4.0 and 7.5 pN/μm when the laser power was 35mW. Dependence of axial optical trapping stiffness on the diameter of the particles was measured with viscous drag method. At last, the origin of the measurement error was discussed.
Directory of Open Access Journals (Sweden)
Shahrokh Shojaeian
2014-01-01
Full Text Available There are always some uncertainties in prediction and estimation of distribution systems loads. These uncertainties impose some undesirable impacts and deviations on power flow of the system which may cause reduction in accuracy of the results obtained by system analysis. Thus, probabilistic analysis of distribution system is very important. This paper proposes a probabilistic power flow technique by applying a normal probabilistic distribution in seven standard deviations on forward-backward algorithm. The losses and voltage of IEEE 33-bus test distribution network is investigated by our new algorithm and the results are compared with the conventional algorithm i.e., based on deterministic methods.
Scholl, M. A.; Ingebritsen, S. E.; Essaid, H. I.
1993-02-01
Fox (1990), in order to explain observations during the Axial Seamount Hydrothermal Emissions Study (ASHES), proposed a conceptual model for a two-phase subsea hydrothermal system in which steam controlled flow patterns by blocking liquid flow. An attempt is made here to demonstrate with a very general model that relative permeability contrasts by themselves do not cause spatial isolation of phases in steam/liquid water systems and that density segregation, independent of relative permeability effects, should not be ruled out as an explanation for the observations at the ASHES site. Fox replies that density segregation is probably not the only mechanism at work.
The influence of bromazepam on cortical power distribution
Directory of Open Access Journals (Sweden)
Isabel Sampaio
2008-06-01
Full Text Available The EEG has been widely employed in the assessment of electrophysiological changes induced by distinct medications. Its sensibility in detecting alterations produced by a specific substance may be enhanced by methods of quantitative analyses (qEEG. The present study aimed at investigating the modulatory effects of bromazepam on brain dynamics. The effects of bromazepam (3mg on EEG power distribution were tested in 10 healthy individuals, in a double-blind experiment. The electrophysiological measure was analyzed across experimental conditions, moments, and electrodes, in the delta, theta, alpha and beta frequency bands separately. A significant decrease of relative power was observed in delta and theta (main effect of condition. No interactions were observed. Although the expected anxiolytic EEG profile was not observed (increased beta and decreased alpha activity, this specific result may be related to other factors such as dosage used and the subjects' general physiological state, and not necessarily to the drug itself.O EEG tem sido amplamente empregado na avaliação de mudanças eletrofisiológicas induzidas por medicações distintas.A sensibilidade desta técnica em detectar alterações produzidas por uma substância pode ser aprimorada por métodos de análise quantitativa (EEGq. O presente estudo teve por objetivo investigar os efeitos modulatórios do bromazepam na dinâmica cerebral. Os efeitos de 3mg de bromazepam na distribuição de potência cortical foram observados em 10 indivíduos sadios, em um desenho duplo-cego. A medida eletrofisiológica foi analisada nas diferentes condições experimentais, momentos e eletrodos, em delta, teta, alfa e beta separadamente. Uma diminuição significativa de potência relativa foi observada em delta e teta (efeito principal para condição. Não foram observadas interações. Embora o perfil ansiolítico do EEG (aumento de beta e diminuição de alfa não tenha sido observado, esteresultado
Hooshyar, Hossein; Vanfretti, Luigi
2013-01-01
Power flow analysis on a Photovoltaic System (PV)dominated distribution network is rather different than a conventional distribution system. This paper proposes a new three-phase power flow solution for such networks that considers the multiphase unbalanced nature of distribution systems together with different system topologies. Power flow contributions of PVs and different types of loads are also considered. The performance of the proposed method has been assessed by simulations on a sample...
Distributed Control of the Power Supply-Demand Balance
Larsen, Gunn K. H.; van Foreest, Nicky D.; Scherpen, Jacquelien M. A.
2013-01-01
This paper aims to achieve a balance of power in a group of prosumers, based on a price mechanism, i.e., to steer the difference between the total production and consumption of power to zero. We first set the information network topology such that the prosumers exchange price (power) information wit
Relay Protection Coordination for Photovoltaic Power Plant Connected on Distribution Network
Nikolovski, Srete; Papuga, Vanja; Knežević, Goran
2014-01-01
This paper presents a procedure and computation of relay protection coordination for a PV power plant connected to the distribution network. In recent years, the growing concern for environment preservation has caused expansion of photovoltaic PV power plants in distribution networks. Numerical computer simulation is an indispensable tool for studying photovoltaic (PV) systems protection coordination. In this paper, EasyPower computer program is used with the module Power Protector. Time-curr...
Distributed reactive power feedback control for voltage regulation and loss minimization
Bolognani, Saverio; Cavraro, Guido; Carli, Ruggero; Zampieri, Sandro
2013-01-01
We consider the problem of exploiting the microgenerators dispersed in the power distribution network in order to provide distributed reactive power compensation for power losses minimization and voltage regulation. In the proposed strategy, microgenerators are smart agents that can measure their phasorial voltage, share these data with the other agents on a cyber layer, and adjust the amount of reactive power injected into the grid, according to a feedback control law that descends from dual...
Power distribution in complex environmental negotiations: Does balance matter?
Burkardt, N.; Lamb, B.L.; Taylor, J.G.
1997-01-01
We studied six interagency negotiations covering Federal Energy Regulatory Commission (FERC) hydroelectric power licenses. Negotiations occurred between state and federal resource agencies and developers over project operations and natural resource mitigation. We postulated that a balance of power among parties was necessary for successful negotiations. We found a complex relationship between balanced power and success and conclude that a balance of power was associated with success in these negotiations. Power played a dynamic role in the bargaining and illuminates important considerations for regulatory design.
Kramers escape rate in overdamped systems with the power-law distribution
Zhou, Yanjun; Du, Jiulin
2014-01-01
Kramers escape rate in the overdamped systems with the power-law distribution is studied. By using the mean first passage time, we derive the escape rate for the power-law distribution and obtain the Kramers' infinite barrier escape rate in this case. It is shown that the escape rate for the power-law distribution extends the Kramers' overdamped result to the relatively low barrier. Furthermore, we apply the escape rate for the power-law distribution to the unfolding of titin and show a bette...
Energy Technology Data Exchange (ETDEWEB)
Treanton, B.; Palomo, J.; Kroposki, B.; Thomas, H.
2006-10-01
The Advanced Power Electronics Interfaces for Distributed Energy Workshop, sponsored by the California Energy Commission Public Interest Energy Research program and organized by the National Renewable Energy Laboratory, was held Aug. 24, 2006, in Sacramento, Calif. The workshop provided a forum for industry stakeholders to share their knowledge and experience about technologies, manufacturing approaches, markets, and issues in power electronics for a range of distributed energy resources. It focused on the development of advanced power electronic interfaces for distributed energy applications and included discussions of modular power electronics, component manufacturing, and power electronic applications.
Directory of Open Access Journals (Sweden)
Dan Wang
2013-08-01
Full Text Available This paper presents research on the voltage and current distortion in the input stage, isolation stage and output stage of Distribution Electronic Power transformer (D-EPT after the open-circuit and short-circuit faults of its power switches. In this paper, the operational principles and the control methods for input stage, isolation stage and output stage of D-EPT, which work as a cascaded H-bridge rectifier, DC-DC converter and inverter, respectively, are introduced. Based on conclusions derived from the performance analysis of D-EPT after the faults, this paper comes up with the effects from its topology design and control scheme on the current and voltage distortion. According to the EPT fault characteristics, since the waveforms of relevant components heavily depend on the location of the faulty switch, it is very easy to locate the exact position of the faulty switch. Finally, the fault characteristics peculiar to D-EPT are analyzed, and further discussed with simulation on the Saber platform, as well as a fault location diagnosis algorithm.
Use of FACTS for enhanced flexibility and efficiency in power transmission and distribution grids
Energy Technology Data Exchange (ETDEWEB)
Grunbaum, Rolf; Wahlberg, Conny; Sannino, Ambra
2010-09-15
The paper shows how the use of FACTS increases flexibility in power transmission and distribution, improving capacity of transmission corridors to integrate renewable power production. Examples included are 69 kV directly connected SVCs for grid stabilization in conjunction with a high degree of wind power penetration; series compensation to evacuate power from the largest wind power installation in USA; SVC to increase the reliability and reduce congestion over a heavily loaded power corridor; thyristor controlled series compensation to increase the dynamic stability and power transmission capability of a power inter-connector. Finally, some applications of Dynamic energy storage are highlighted.
STABILITY OF AXIAL VIBRATION OF POWER TRANSFORMER WINDINGS%电力变压器绕组轴向振动稳定性分析
Institute of Scientific and Technical Information of China (English)
王璋奇; 王孟
2002-01-01
This paper deals with the electromechanical coupled vibration problem in transformer. A new dynamic model for the axial vibration of transformer's winding is presented. The transformer leakage magnetic field is simplified to a 2-dimensional magnetic field, and analytic formulation of the transformer leakage field is obtained. Base on the Lagrange equation of electromechanical coupled system, the nonlinear and simplified linear electromechanical coupled axial vibration equations of windings are obtained. The stability of the axial vibration of the transformer windings is analyzed by means of the dynamics theory. Using designed transformer model as an example, it is shown that instability occurs during high currents, and the stability and instability regions of design parameters are obtained.%研究了变压器绕组的机电耦合振动稳定性问题,建立了变压器绕组轴向机电耦合的动力学模型.将变压器绕组的漏磁场简化成二维磁场,得到其解析解,采用机电耦合系统的Lagrange方程,分析得到变压器绕组机电耦合的非线性振动方程,以及简化的耦合振动方程.应用动力学理论分析载流的变压器绕组轴向振动的稳定性,得到了模型变压器绕组主要设计参数的稳定域和不稳定域,分析大电流引起变压器绕组失稳的机理.
Improving Power Quality in Low-Voltage Networks Containing Distributed Energy Resources
Mazumder, Sumit; Ghosh, Arindam; Zare, Firuz
2013-05-01
Severe power quality problems can arise when a large number of single-phase distributed energy resources (DERs) are connected to a low-voltage power distribution system. Due to the random location and size of DERs, it may so happen that a particular phase generates excess power than its load demand. In such an event, the excess power will be fed back to the distribution substation and will eventually find its way to the transmission network, causing undesirable voltage-current unbalance. As a solution to this problem, the article proposes the use of a distribution static compensator (DSTATCOM), which regulates voltage at the point of common coupling (PCC), thereby ensuring balanced current flow from and to the distribution substation. Additionally, this device can also support the distribution network in the absence of the utility connection, making the distribution system work as a microgrid. The proposals are validated through extensive digital computer simulation studies using PSCADTM.
Directory of Open Access Journals (Sweden)
Adesina, L.M
2015-07-01
Full Text Available The solution to power flow is one of the most important problems in electrical power systems. Traditional methods have been previously used for power flow analysis, but with prevalent drawbacks such as abnormal operating solutions and divergences in heavy loads. This paper presents power flow analysis in a power system, by modelling a typical 33kV Distribution Network, and simulating using the NEPLAN software for power flow studies. Island Business Unit’s (IBU 33kV network of Eko Electricity Distribution Plc (EKEDP for a scenario day is taken as case study in the analysis. The most important parameters of power flow analysis is utilized to find the magnitude and phase angles of the voltages at each Busbar, as well as the real and reactive power flowing through each distribution line within the network under consideration.
Sandrock, H.E.
1982-05-06
Static axial mixing apparatus includes a plurality of channels, forming flow paths of different dimensions. The axial mixer includes a flow adjusting device for adjustable selective control of flow resistance of various flow paths in order to provide substantially identical flows through the various channels, thereby reducing nonuniform coating of interior surfaces of the channels. The flow adjusting device may include diaphragm valves, and may further include a pressure regulating system therefor.
Surface nanoscale axial photonics
Sumetsky, M.; Fini, J. M.
2011-01-01
Dense photonic integration promises to revolutionize optical computing and communications. However, efforts towards this goal face unacceptable attenuation of light caused by surface roughness in microscopic devices. Here we address this problem by introducing Surface Nanoscale Axial Photonics (SNAP). The SNAP platform is based on whispering gallery modes circulating around the optical fiber surface and undergoing slow axial propagation readily described by the one-dimensional Schr\\"odinger e...
Topology investigation of front end DC/DC converter for distributed power system
Yang, Bo
2003-01-01
Topology Investigation of Front End DC/DC Power Conversion for Distributed Power System by Bo Yang Fred C. Lee, Chairman Electrical Engineering (Abstract) With the fast advance in VLSI technology, smaller, more powerful digital system is available. It requires power supply with higher power density, lower profile and higher efficiency. PWM topologies have been widely used for this application. Unfortunately, hold up time requirement put huge penalties on the performance o...
Bohnenstiehl, D. R.; Howell, J. K.; Hey, R. N.
2008-12-01
Deep-towed DSL-120 bathymetric data are used to investigate the pattern of lava dome formation along a superfast spreading portion of the southern East Pacific Rise (EPR), including the overlapping limbs of a giant (120 × 120 km) propagator near 29°S. Along the 670 km of the axis surveyed, 1172 small domes were identified using a closed contour algorithm. Their abundance, defined by spatial density, is well correlated with the along-axis relief of the ridge crest. Where the western and eastern limbs plunge toward the overlap zone, densities are high (3-6 km-2); however, where the axial depth profile is shallow and flat, densities are comparably low (0.4 km-2). Volcanic domes within the low abundance areas are characterized by lower ratios of height to basal radius (0.15 versus 0.22), smaller maximum heights (18 versus 40 m), and a larger relative percentage of small versus large mounds. The zone of high dome abundance encompasses the overlapping limbs of the rift and extends more than 100 km to the north and south beyond the overlap zone. Domes form dominantly during low effusion rate, point-source eruptions, which suggests that discontinuous melt lenses underlie the ridge axis proximal to the overlapper. Conversely, fissure-fed sheet flows dominate along the more distal segments, implying the presence of a more continuous axial magma lens. Throughout the survey area, dome abundance increases systematically near second-order segment boundaries. Within the high abundance zone, some third-order offsets also correlate with increased dome production, but local peaks in abundance are not tied exclusively to higher-order ridge offsets. Where dome abundance is low, domes are clustered tightly near second-order offsets and there is no increase in dome abundance near third-order segment boundaries.
DEFF Research Database (Denmark)
Chen, Shuheng; Hu, Weihao; Chen, Zhe
2016-01-01
and distributed generators’ reactive powers in order to minimize comprehensive cost. Corresponding constraints, including voltage profile, maximum allowable daily switching operation numbers (MADSON), reactive power limits, and so on, are considered. The strategy of grouping branches is used to simplify...... the formulated mathematical problem and a hybrid particle swarm optimization (HPSO) method is presented to search the optimal solution. Fuzzy adaptive inference is integrated into basic HPSO method in order to avoid being trapped in local optima. The proposed fuzzy adaptive inference based hybrid PSO algorithm...... cost minimization in distribution systems with distributed generators....
Wind Power Forecasting Error Distributions: An International Comparison
DEFF Research Database (Denmark)
Hodge, Bri-Mathias; Lew, Debra; Milligan, Michael;
2012-01-01
Wind power forecasting is essential for greater penetration of wind power into electricity systems. Because no wind forecasting system is perfect, a thorough understanding of the errors that may occur is a critical factor for system operation functions, such as the setting of operating reserve le...
Institute of Scientific and Technical Information of China (English)
张发军; 刘中; 周长; 雷祎
2013-01-01
通过对金属带式无级变速器CVT(Continuously Variable Transmission)中金属带的轴向偏斜现象描述并深入分析其产生的机理,计算出金属带式无级变速器变速过程中金属带的轴向偏斜量数学解析模型C.同时,基于金属带偏斜对功率损失的影响分析,推导出由金属带偏斜而造成的功率损失计算式.最后以VDT公司的P811型金属带为研究对象,计算出由于金属带偏斜而产生的功率损失具体数据,并将其与不考虑偏斜时的功率损失数据进行对比,从而得出金属带的偏斜所导致传递功率损失的百分比大小.%Through the metal belt type stepless transmission metal about the axial deviation phenomenon in CVT,the mechanism is described and analysed,then the mathematical analytical model C of metal belt type stepless transmission speed in the process of metal axial deviation is calculated.At the same time,the expression of the power loss caused by metal belt deviation is deduced based on the metal belt deflection in the power loss.At last,the specific data of the loss of power is calculated according to the VDT company type P811 metal band,and compared to the power loss data no consider deviation,finally,the percentage of power loss caused by metal transfer deviation is obtained.
Operation of Modern Distribution Power Systems in Competitive Electricity Markets
DEFF Research Database (Denmark)
Hu, Weihao
, DG units, loads and electricity price are studied. Further, the effect of energy storage systems will be considered, and an optimal operation strategy for energy storage devices in a large scale wind power system in the electricity market is proposed. The western Danish power system, which has large...... penetrations of variable wind power production and may represent the future electricity markets in some ways, is chosen as the studied power system. 10 year actual data from the Danish competitive electricity market are collected and analyzed. The relationship among the electricity price, the consumption...... strategy for trading wind power in the Danish short-term electricity market in order to minimize the imbalance costs for regulation. A load optimization method based on spot price for demand side management in Denmark is proposed in order to save the energy costs for 3 types of typical Danish consumers...
Axial Force at the Vessel Bottom Induced by Axial Impellers
I. Fořt; P. Hasal; A. Paglianti; F. Magelli
2008-01-01
This paper deals with the axial force affecting the flat bottom of a cylindrical stirred vessel. The vessel is equipped with four radial baffles and is stirred with a four 45° pitched blade impeller pumping downwards. The set of pressure transducers is located along the whole radius of the flat bottom between two radial baffles. The radial distribution of the dynamic pressures indicated by the transducers is measured in dependence on the impeller off-bottom clearance and impeller speed.It fol...
A Survey on Control of Electric Power Distributed Generation Systems for Microgrid Applications
DEFF Research Database (Denmark)
Bouzid, Allal; Guerrero, Josep M.; Cheriti, Ahmed;
2015-01-01
The introduction of microgrids in distribution networks based on power electronics facilitates the use of renewable energy resources, distributed generation (DG) and storage systems while improving the quality of electric power and reducing losses thus increasing the performance and reliability o...
Energy Technology Data Exchange (ETDEWEB)
Jatuff, F.; Krouthen, J.; Helmersson, S.; Chawla, R
2004-03-01
A significant source of uncertainty in Boiling Water Reactor physics is associated with the precise characterisation of the axially-dependent neutron moderation properties of the coolant inside the fuel assembly channel, and the corresponding effects on reactor physics parameters such as the lattice neutron multiplication, the neutron migration length, and the pin-by-pin power distribution. In this paper, the effects of particularly relevant void fraction uncertainties on reactor physics parameters have been studied for a BWR assembly of type Westinghouse SVEA-96 using the CASMO-4, HELIOS/PRESTO-2 and MCNP4C codes. The SVEA-96 geometry is characterised by the sub-division of the assembly into four different sub-bundles by means of an inner bypass with a cruciform shape. The study has covered the following issues: (a) the effects of different cross-section data libraries on the void coefficient of reactivity, for a wide range of void fractions; (b) the effects due to a heterogeneous vs. homogeneous void distribution inside the sub-bundles; and (c) the consequences of partly inserted absorber blades producing different void fractions in different sub-bundles. (author)
Development of An On-Line, Core Power Distribution Monitoring System
Energy Technology Data Exchange (ETDEWEB)
Tunc ALdemir; Don Miller; Peng Wang
2007-10-02
The objective of the proposed work was to develop a software package that can construct in three-dimensional core power distributions using the signals from constant temperature power sensors distributed in the reactor core. The software developed uses a mode-based state/parameter estmation technique that is particularly attractive when there are model uncertainties and/or large signal noise. The software yields the expected value of local power at the detector locations and points in between, as well as the probability distribution of the local power density
Power system services provided by inverter connected distributed energy resources
DEFF Research Database (Denmark)
For the last few years there has been a significant increase of DER units in Denmark, of those units more and more are connected to the power system using inverters. These inverter connected units have the potential to support the electrical power system with various power system services. One of...... of the services that can be provided is local voltage support. This brings up the question of how the voltage support function is implemented to control multiple DER units as well as how the response of the units can be estimated and evaluated....
Power system services provided by inverter connected distributed energy resources
Isleifsson, Fridrik Rafn
2011-01-01
For the last few years there has been a significant increase of DER units in Denmark, of those units more and more are connected to the power system using inverters. These inverter connected units have the potential to support the electrical power system with various power system services. One of the services that can be provided is local voltage support. This brings up the question of how the voltage support function is implemented to control multiple DER units as well as how the response of...
Reactive power balance in a distribution network with wind farms and CHPS
DEFF Research Database (Denmark)
Lund, Torsten; Nielsen, John Eli; Hylle, Per;
2007-01-01
In Denmark, a large part of the electricity is generated by wind turbines and combined heat and power plants. Most of them are connected to the distribution systems. In periods with high wind speeds, large flows of reactive power have been observed between the 150kV and the 60 kV systems. The tra......In Denmark, a large part of the electricity is generated by wind turbines and combined heat and power plants. Most of them are connected to the distribution systems. In periods with high wind speeds, large flows of reactive power have been observed between the 150kV and the 60 kV systems....... The transfer of reactive power reduces the capacity of the lines, causes thermal losses and can in some cases reduce the voltage stability margin of the system. To identify the origin of the problem, an actual distribution system with a high penetration of wind power and distributed generation has been...
Sharpe, Matthew Michael
1990-01-01
CIVINS Approved for public release ; distribution is unlimited Observed distributions of wave heights and periods taken from one year of surface wave monitoring near Martha's Vineyard are compared to distributions based on narrow-band theory. The joint distributions of wave heights and periods and the marginal height distributions are examined. The observed significant wave heights and periods of the extreme waves are also studied. Seas are classified by the shapes of their power densit...
Self-Powered WSN for Distributed Data Center Monitoring
Directory of Open Access Journals (Sweden)
Davide Brunelli
2016-01-01
Full Text Available Monitoring environmental parameters in data centers is gathering nowadays increasing attention from industry, due to the need of high energy efficiency of cloud services. We present the design and the characterization of an energy neutral embedded wireless system, prototyped to monitor perpetually environmental parameters in servers and racks. It is powered by an energy harvesting module based on Thermoelectric Generators, which converts the heat dissipation from the servers. Starting from the empirical characterization of the energy harvester, we present a power conditioning circuit optimized for the specific application. The whole system has been enhanced with several sensors. An ultra-low-power micro-controller stacked over the energy harvesting provides an efficient power management. Performance have been assessed and compared with the analytical model for validation.
Self-Powered WSN for Distributed Data Center Monitoring
Brunelli, Davide; Passerone, Roberto; Rizzon, Luca; Rossi, Maurizio; Sartori, Davide
2016-01-01
Monitoring environmental parameters in data centers is gathering nowadays increasing attention from industry, due to the need of high energy efficiency of cloud services. We present the design and the characterization of an energy neutral embedded wireless system, prototyped to monitor perpetually environmental parameters in servers and racks. It is powered by an energy harvesting module based on Thermoelectric Generators, which converts the heat dissipation from the servers. Starting from the empirical characterization of the energy harvester, we present a power conditioning circuit optimized for the specific application. The whole system has been enhanced with several sensors. An ultra-low-power micro-controller stacked over the energy harvesting provides an efficient power management. Performance have been assessed and compared with the analytical model for validation. PMID:26729135
Self-Powered WSN for Distributed Data Center Monitoring.
Brunelli, Davide; Passerone, Roberto; Rizzon, Luca; Rossi, Maurizio; Sartori, Davide
2016-01-01
Monitoring environmental parameters in data centers is gathering nowadays increasing attention from industry, due to the need of high energy efficiency of cloud services. We present the design and the characterization of an energy neutral embedded wireless system, prototyped to monitor perpetually environmental parameters in servers and racks. It is powered by an energy harvesting module based on Thermoelectric Generators, which converts the heat dissipation from the servers. Starting from the empirical characterization of the energy harvester, we present a power conditioning circuit optimized for the specific application. The whole system has been enhanced with several sensors. An ultra-low-power micro-controller stacked over the energy harvesting provides an efficient power management. Performance have been assessed and compared with the analytical model for validation. PMID:26729135
Simulation Environment for Power Management and Distribution Development Project
National Aeronautics and Space Administration — The overall objective of this research project is to investigate an autonomous and online control structure for finite-inertia power systems (dc and ac) with a...
Simulation Environment for Power Management and Distribution Development Project
National Aeronautics and Space Administration — The overall objective of this research project is to investigate autonomous control architectures for spacecraft power systems. Such techniques will be critical for...
Self-Powered WSN for Distributed Data Center Monitoring.
Brunelli, Davide; Passerone, Roberto; Rizzon, Luca; Rossi, Maurizio; Sartori, Davide
2016-01-02
Monitoring environmental parameters in data centers is gathering nowadays increasing attention from industry, due to the need of high energy efficiency of cloud services. We present the design and the characterization of an energy neutral embedded wireless system, prototyped to monitor perpetually environmental parameters in servers and racks. It is powered by an energy harvesting module based on Thermoelectric Generators, which converts the heat dissipation from the servers. Starting from the empirical characterization of the energy harvester, we present a power conditioning circuit optimized for the specific application. The whole system has been enhanced with several sensors. An ultra-low-power micro-controller stacked over the energy harvesting provides an efficient power management. Performance have been assessed and compared with the analytical model for validation.
Institute of Scientific and Technical Information of China (English)
刘建庄; 张农; 韩昌良
2012-01-01
Planar and 3-D mechanical models were used to test rock-bolt pull out. The results were used to derive formulas for the axial force and bond shear stress in the bolt under elastic conditions. A new term, the decay of shear stress coefficient, is proposed that has an obvious effect on the stress distributions. Theoretical estimates of how cement or resin-anchored bolt stresses decay in sandstone rock are presented. These estimates are then compared to bolt properties in a coal body. Axial force and grout shear stress in soft rock are found to be distrib- uted along the entire length of the bolt. However, in hard rock the axial force decays rapidly, dropping by 95 percent along 80 to 100 cm in the grout. The grout shear stress decays to 0.06 MPa within about 40 to 50 cm in the grout.%通过构建平面和三维力学模型,推导了弹性状态下沿杆长方向轴力和黏结剪应力的分布函数,提出了锚杆剪应力衰减系数的概念,并给出了力学算式;对比分析了围岩为砂岩和煤体时,水泥锚固和树脂锚固两种情况下,锚杆轴力和剪力的衰减特征.结果表明：软岩锚固中轴力和剪力为全长分布型,硬岩0.8-1.0m左右即衰减为拉拔力的5%,黏结剪应力的主要作用范围为0-0.5m,在0.4-0.5m处衰减为0.06MPa左右.
Digital Control of Converters for Distributed Power Generations
Skjellnes, Tore
2008-01-01
Pulse width modulated converters are becoming increasingly popular as their cost decreases and power rating increases. The new trend of smallscale power producers, often using renewable energy sources, has created new demands for delivery of energy to the grid.A major advantage of the pulse width modulated converter is the ability to control the output voltage at any point in the voltage period. This enables rapid response to load changes and non-linear loads. In addition it can shape the vol...
Distributed Energy Systems with Wind Power and Energy Storage
Korpås, Magnus
2004-01-01
The topic of this thesis is the study of energy storage systems operating with wind power plants. The motivation for applying energy storage in this context is that wind power generation is intermittent and generally difficult to predict, and that good wind energy resources are often found in areas with limited grid capacity. Moreover, energy storage in the form of hydrogen makes it possible to provide clean fuel for transportation. The aim of this work has been to evaluate how local energy s...
Power-law distribution functions derived from maximum entropy and a symmetry relationship
Peterson, G. J.; Dill, K. A.
2011-01-01
Power-law distributions are common, particularly in social physics. Here, we explore whether power-laws might arise as a consequence of a general variational principle for stochastic processes. We describe communities of 'social particles', where the cost of adding a particle to the community is shared equally between the particle joining the cluster and the particles that are already members of the cluster. Power-law probability distributions of community sizes arise as a natural consequence...
Electrical Load Forecasting in Power Distribution Network by Using Artificial Neural Network
Ali Nahari; Habib Rostami; Rahman Dashti
2013-01-01
Today, one of most important concerns in electrical power markets and distribution network is supplying the customer demands. In order to manage the market it is necessary to forecast the usage of electrical power in distribution network. The pattern of electrical power usage depends on many different parameters such as the week days, seasons, weather condition and etc. Today, researchers by using an artificial intelligence based on the natural intelligence are trying to forecast the costumer...
A High Power Density DC-DC Converter for Distributed PV Architectures
Energy Technology Data Exchange (ETDEWEB)
Agamy, Mohammed S; Chi, Song; Elasser, Ahmed; Harfman-Todorovic, Maja; Jiang, Yan; Mueller, Frank; Tao, Fengfeng
2012-06-01
In order to maximize solar energy harvesting capabilities, power converters have to be designed for high efficiency and good MPPT and voltage/current performance. When many converters are used in distributed systems, power density also becomes an important factor as it allows for simpler system integration. In this paper a high power density string dc-dc converter suitable for distributed medium to large scale PV installation is presented. A simple partial power processing topology, implemented with all silicon carbide devices provides high efficiency as well as high power density. A 3.5kW, 100kHz converter is designed and tested to verify the proposed methods.
A MILP-Based Distribution Optimal Power Flow Model for Microgrid Operation
Energy Technology Data Exchange (ETDEWEB)
Liu, Guodong [ORNL; Starke, Michael R [ORNL; Zhang, Xiaohu [ORNL; Tomsovic, Kevin [University of Tennessee, Knoxville (UTK)
2016-01-01
This paper proposes a distribution optimal power flow (D-OPF) model for the operation of microgrids. The proposed model minimizes not only the operating cost, including fuel cost, purchasing cost and demand charge, but also several performance indices, including voltage deviation, network power loss and power factor. It co-optimizes the real and reactive power form distributed generators (DGs) and batteries considering their capacity and power factor limits. The D-OPF is formulated as a mixed-integer linear programming (MILP). Numerical simulation results show the effectiveness of the proposed model.
Optimization of residual heat removal pump axial thrust and axial bearing
Energy Technology Data Exchange (ETDEWEB)
Schubert, F.
1996-12-01
The residual heat removal (RHR) pumps of German 1300 megawatt pressurized-water reactor (PWR) power plants are of the single stage end suction type with volute casing or with diffuser and forged circular casing. Due to the service conditions the pumps have to cover the full capacity range as well as a big variation in suction static pressure. This results in a big difference in the axial thrust that has to be borne by the axial bearing. Because these pumps are designed to operate without auxiliary systems (things that do not exist can not fail), they are equipped with antifriction bearings and sump oil lubrication. To minimize the heat production within the bearing casing, a number of PWR plants have pumps with combined axial/radial bearings of the ball type. Due to the fact that the maximum axial thrust caused by static pressure and hydrodynamic forces on the impeller is too big to be borne by that type of axial bearing, the impellers were designed to produce a hydrodynamic axial force that counteracts the static axial force. Thus, the resulting axial thrust may change direction when the static pressure varies.
CFD Simulation of Casing Treatment of Axial Flow Compressors
DeWitt, Kenneth
2005-01-01
A computational study is carried out to understand the physical mechanism responsible for the improvement in stall margin of an axial flow rotor due to the circumferential casing grooves. It is shown that the computational tool used predicts an increase in operating range of the rotor when casing grooves are present. A budget of the axial momentum equation is carried out at the rotor casing in the tip gap in order to uncover the physical process behind this stall margin improvement. It is shown that for the smooth casing the net axial pressure force . However in the presence of casing grooves the net axial shear stress force acting at the casing is augmented by the axial force due to the radial transport of axial momentum, which occurs across the grooves and power stream interface. This additional force adds to the net axial viscous sheer force and thus leads to an increase in the stall margin of the rotor.
Constructing the probability distribution function for the total capacity of a power system
Energy Technology Data Exchange (ETDEWEB)
Vasin, V.P.; Prokhorenko, V.I.
1980-01-01
The difficulties involved in constructing the probability distribution function for the total capacity of a power system consisting of numerous power plants are discussed. A method is considered for the approximate determination of such a function by a Monte Carlo method and by exact calculation based on special recursion formulas on a particular grid of argument values. It is shown that there may be significant deviations between the true probability distribution and a normal distribution.
Prospects of Custom Power Devices in Improving Reliability of Distribution Networks in Nigeria
Directory of Open Access Journals (Sweden)
Onohaebi S. O.
2014-09-01
Full Text Available Nigeria power distribution network is faced with enormous challenges such as consistent overloading of distribution lines and transformers, power outages due to various kinds of faults such as planned, unplanned and forced, high distribution line losses, poor power quality among others. The attempt by Federal Government of Nigeria (FGN to solve power system challenges has resulted into the creation of eleven (11 distribution companies (Discos. These include Ibadan, Kaduna, Port Harcourt, Jos, Benin, Eko, Ikeja, Kano, Yola, Abuja and Enugu. However the FGN did not consider the use of custom power devices in solving some of these problems inherent in the distribution networks. These devices are power electronic based with fast switching mechanism and has found vast application in distribution networks in developed countries. This paper considered the prospect of Custom Power (CP devices such as Solid State Transfer Switch (SSTS, Dynamic Static Compensator (D-STATCOM, Dynamic Voltage Restorer (DVR and Unified Power Quality Controller (UPQC in improving the efficiency of Nigeria distribution network
Modeling and Simulation of Power Distribution System in More Electric Aircraft
Directory of Open Access Journals (Sweden)
Zhangang Yang
2015-01-01
Full Text Available The More Electric Aircraft concept is a fast-developing trend in modern aircraft industry. With this new concept, the performance of the aircraft can be further optimized and meanwhile the operating and maintenance cost will be decreased effectively. In order to optimize the power system integrity and have the ability to investigate the performance of the overall system in any possible situations, one accurate simulation model of the aircraft power system will be very helpful and necessary. This paper mainly introduces a method to build a simulation model for the power distribution system, which is based on detailed component models. The power distribution system model consists of power generation unit, transformer rectifier unit, DC-DC converter unit, and DC-AC inverter unit. In order to optimize the performance of the power distribution system and improve the quality of the distributed power, a feedback control network is designed based on the characteristics of the power distribution system. The simulation result indicates that this new simulation model is well designed and it works accurately. Moreover, steady state performance and transient state performance of the model can fulfill the requirements of aircraft power distribution system in the realistic application.
Power Management for A Distributed Wireless Health Management Architecture
National Aeronautics and Space Administration — Distributed wireless architectures for prognostics is an important enabling step in prognostic research in order to achieve feasible real-time system health...
Control strategies for power distribution networks with electric vehicles integration
DEFF Research Database (Denmark)
Hu, Junjie
control, market based control, and price control. The thesis investigates new approaches for distribution networks congestion management. It suggests and develops a market based control for distribution grid congestion management. The general equilibrium market mechanism is utilized in the operation....... EVs can absorb energy during periods of high electricity production and feed the electricity back into the grid when the demand is high or in situations of insucient electricity generation. However, extra loads created by the increasing number of EVs may have adverse impacts on the distribution...... network such as congestion. These factors will bring new challenges to the distribution system operator. Typically, the challenges are solved by expanding the grid to t the size and the pattern of the demand. As an alternative, the capacity problem can also be solved smartly using advanced control...
Optimal power flow management for distributed energy resources with batteries
International Nuclear Information System (INIS)
Highlights: • A PV-diesel-battery hybrid system is proposed. • Model minimizes fuel and battery wear costs. • Power flows are analysed in a 24-h period. • Results provide a practical platform for decision making. - Abstract: This paper presents an optimal energy management model of a solar photovoltaic-diesel-battery hybrid power supply system for off-grid applications. The aim is to meet the load demand completely while satisfying the system constraints. The proposed model minimizes fuel and battery wear costs and finds the optimal power flow, taking into account photovoltaic power availability, battery bank state of charge and load power demand. The optimal solutions are compared for cases when the objectives are weighted equally and when a larger weight is assigned to battery wear. A considerable increase in system operational cost is observed in the latter case owing to the increased usage of the diesel generator. The results are important for decision makers, as they depict the optimal decisions considered in the presence of trade-offs between conflicting objectives
Site selection and evaluation for nuclear power plants with respect to population distribution
International Nuclear Information System (INIS)
This safety guide, relating population distribution to site selection and evaluation, for nuclear power plants, forms part of the IAEA's programme, referred to as the NUSS programme (Nuclear Safety Standards). The guide presents population distribution data, requirements, examples of site screening methods, and an overview of radiological impact assessment with respect to population distribution
Directory of Open Access Journals (Sweden)
F. Aguilar Parés
1999-01-01
Full Text Available Durante el movimiento de un material en un transportador de sinfín surge una fuerza en dirección axial que influye en laselección de uno de los cojinetes de apoyo del equipo. En el artículo aparecen algunas soluciones constructivas que tienen encuentan la fuerza axial. Por otro lado se establece la relación entre la fuerza axial y el empuje axial y se precisa de quiendepende el sentido del empuje axial. Por último se propone un modelo matemático que relaciona la fuerza axial con la potenciarequerida por el equipo.Palabras claves: Transportador de sinf in, fuerza axial , empuje axial ._________________________________________________________________________AbstractDuring the movement of material in a screw conveyor surge a force in axial direction that influence in the selection of one ofthe equipment support bearings. Some constructive solutions appear in the article for considering the axial force. In the otherhand it is established the relation between axial force and axial thurst and it is precised whose direction thurst axial depend of.Finally it is proposed a mathematic model that relates the axial force with the power required by the equipment.Key words: Screw conveyor, axial force, axial thurst .
Electrical Market Management Considering Power System Constraints in Smart Distribution Grids
Poria Hasanpor Divshali; Bong Jun Choi
2016-01-01
Rising demand, climate change, growing fuel costs, outdated power system infrastructures, and new power generation technologies have made renewable distribution generators very attractive in recent years. Because of the increasing penetration level of renewable energy sources in addition to the growth of new electrical demand sectors, such as electrical vehicles, the power system may face serious problems and challenges in the near future. A revolutionary new power grid system, called smart g...
System Implications of the Different Powering Distributions for the ATLAS Upgrade Strips Tracker
Díez, S
2012-01-01
This paper compares the two novel approaches for the power distribution of the ATLAS Upgrade strips tracker modules, serial and DC-DC powering, from the point of view of a system. Numerous variables have been taken into account, such as total power dissipation and power efficiency, system reliability and protection, noise performances, impact on the material budget of the tracker, and services needs and re-usability.
Optimal Power Flow in Islanded Microgrids Using a Simple Distributed Algorithm
DEFF Research Database (Denmark)
Sanseverino, Eleonora Riva; Di Silvestre, Maria Luisa; Badalamenti, Romina;
2015-01-01
communication channels, since only closeby nodes will exchange information. The correction of generated active powers is possible by means of the active power losses partition concept that attributes a portion of the overall power losses in each branch to each generator. The experimental part shows the first...... results of the proposed method on an islanded microgrid. Simulation results of the distributed algorithm are compared to a centralized Optimal Power Flow approach and very small errors can be observed....
Modeling, control, and dispatch of photovoltaic-based power distribution systems
Carrasco, Miguel
Small-scale generators, also called distributed generators (DGs), are primed to play a central role in future distribution systems. If properly integrated, DGs present two main advantages: (i) they help decongest existing transmission grids; and (ii) CO2 emissions are reduced since most DGs are based on renewables like wind and solar. Their integration into distribution systems is one of the main challenges the power industry will be facing in the coming years. Photovoltaic (PV) power generation represents a key technology for realizing the DG concept. In this dissertation, technical solutions are developed that enable an increased penetration of PV systems, while improving the efficiency, reliability, and power quality of power distribution grids. The presented research spans from PV array modeling, parameter identification and estimation methods, through advanced control strategies for the power electronic interfaces, to system--level optimal dispatch strategies. Simulation-based and experimental validation results show the performance of the proposed techniques.
Directory of Open Access Journals (Sweden)
Runhai Jiao
2015-01-01
Full Text Available This paper puts forward a novel particle swarm optimization algorithm with quantum behavior (QPSO to solve reactive power optimization in power system with distributed generation. Moreover, differential evolution (DE operators are applied to enhance the algorithm (DQPSO. This paper focuses on the minimization of active power loss, respectively, and uses QPSO and DQPSO to determine terminal voltage of generators, and ratio of transformers, switching group number of capacitors to achieve optimal reactive power flow. The proposed algorithms are validated through three IEEE standard examples. Comparing the results obtained from QPSO and DQPSO with those obtained from PSO, we find that our algorithms are more likely to get the global optimal solution and have a better convergence. What is more, DQPSO is better than QPSO. Furthermore, with the integration of distributed generation, active power loss has decreased significantly. Specifically, PV distributed generations can suppress voltage fluctuation better than PQ distributed generations.
Distributed energy systems with wind power and energy storage
Energy Technology Data Exchange (ETDEWEB)
Korpaas, Magnus
2004-07-01
The topic of this thesis is the study of energy storage systems operating with wind power plants. The motivation for applying energy storage in this context is that wind power generation is intermittent and generally difficult to predict, and that good wind energy resources are often found in areas with limited grid capacity. Moreover, energy storage in the form of hydrogen makes it possible to provide clean fuel for transportation. The aim of this work has been to evaluate how local energy storage systems should be designed and operated in order to increase the penetration and value of wind power in the power system. Optimization models and sequential and probabilistic simulation models have been developed for this purpose. Chapter 3 presents a sequential simulation model of a general wind hydrogen energy system. Electrolytic hydrogen is used either as a fuel for transportation or for power generation in a stationary fuel cell. The model is useful for evaluating how hydrogen storage can increase the penetration of wind power in areas with limited or no transmission capacity to the main grid. The simulation model is combined with a cost model in order to study how component sizing and choice of operation strategy influence the performance and economics of the wind-hydrogen system. If the stored hydrogen is not used as a separate product, but merely as electrical energy storage, it should be evaluated against other and more energy efficient storage options such as pumped hydro and redox flow cells. A probabilistic model of a grid-connected wind power plant with a general energy storage unit is presented in chapter 4. The energy storage unit is applied for smoothing wind power fluctuations by providing a firm power output to the grid over a specific period. The method described in the chapter is based on the statistical properties of the wind speed and a general representation of the wind energy conversion system and the energy storage unit. This method allows us to
Prestorm estimation of hurricane damage to electric power distribution systems.
Guikema, Seth D; Quiring, Steven M; Han, Seung-Ryong
2010-12-01
Hurricanes frequently cause damage to electric power systems in the United States, leading to widespread and prolonged loss of electric service. Restoring service quickly requires the use of repair crews and materials that must be requested, at considerable cost, prior to the storm. U.S. utilities have struggled to strike a good balance between over- and underpreparation largely because of a lack of methods for rigorously estimating the impacts of an approaching hurricane on their systems. Previous work developed methods for estimating the risk of power outages and customer loss of power, with an outage defined as nontransitory activation of a protective device. In this article, we move beyond these previous approaches to directly estimate damage to the electric power system. Our approach is based on damage data from past storms together with regression and data mining techniques to estimate the number of utility poles that will need to be replaced. Because restoration times and resource needs are more closely tied to the number of poles and transformers that need to be replaced than to the number of outages, this pole-based assessment provides a much stronger basis for prestorm planning by utilities. Our results show that damage to poles during hurricanes can be assessed accurately, provided that adequate past damage data are available. However, the availability of data can, and currently often is, the limiting factor in developing these types of models in practice. Opportunities for further enhancing the damage data recorded during hurricanes are also discussed. PMID:21039701
Protecting Intelligent Distributed Power Grids against Cyber Attacks
Energy Technology Data Exchange (ETDEWEB)
Dong Wei; Yan Lu; Mohsen Jafari; Paul Skare; Kenneth Rohde
2010-12-31
Like other industrial sectors, the electrical power industry is facing challenges involved with the increasing demand for interconnected operations and control. The electrical industry has largely been restructured due to deregulation of the electrical market and the trend of the Smart Grid. This moves new automation systems from being proprietary and closed to the current state of Information Technology (IT) being highly interconnected and open. However, while gaining all of the scale and performance benefits of IT, existing IT security challenges are acquired as well. The power grid automation network has inherent security risks due to the fact that the systems and applications for the power grid were not originally designed for the general IT environment. In this paper, we propose a conceptual layered framework for protecting power grid automation systems against cyber attacks. The following factors are taken into account: (1) integration with existing, legacy systems in a non-intrusive fashion; (2) desirable performance in terms of modularity, scalability, extendibility, and manageability; (3) alignment to the 'Roadmap to Secure Control Systems in the Energy Sector' and the future smart grid. The on-site system test of the developed prototype security system is briefly presented as well.
Chen, S. L.; Ravelo, A. C.; Clague, D. A.
2015-12-01
The California Current is an upwelling region with dynamic interactions between circulation, biological productivity and ecology. A 77 cm piston push core was taken from the Juan de Fuca Ridge Axial Seamount using a Remotely Operated Vehicle (ROV) (2213m, 45.55º N, 130.08º W), an active submarine volcano ~480 km off Oregon's coast. Five radiocarbon dates indicate that the sediment ranges from 42.6 ka at 77 cm to 17.6 ka at 15 cm, with an average sediment accumulation rate of 2.47 cm/ka from 77-15 cm, and an average rate of 0.85 cm/ka during the postglacial period (changes in vertical and seasonal temperature since Marine Isotope Stage 3 (MIS3). Measurements of δ18O of the upwelling species Globigerina bulloides, the thermocline dwelling species Neogloboquadrina dutertrei, and the warm mixed-layer species Orbulina universa are offset from each other, reflecting vertical and seasonal variation among the planktonic foraminifera. Of the three species, G. bulloides shows the least variation in δ18O, possibly indicating that marked changes in temperature are masking changes in the δ18O of seawater due to global ice volume changes. G. bulloides and O. universa δ18O values are similar in MIS 3 and diverge with time, indicating the development of strong seasonal succession of species, since the last glacial maximum. Bulk nitrogen isotopes and nitrogen flux provide additional constraints on upwelling strength and insight into local biological productivity and nutrient dynamics. Obtaining Mg/Ca data will clarify the δ 18O interpretation except deep in the core where metal-bearing authigenic precipitates affect Mg concentrations. These climatic proxies together provide insight into how global climate change and local seamount volcanism impacts regional productivity in the California Current.
DEFF Research Database (Denmark)
Chen, Shuheng; Hu, Weihao; Su, Chi;
2015-01-01
and capacitors, and subject to constraints such as minimum and maximum reactive power limits of distributed generators, maximum deviation of bus voltages, maximum allowable daily switching operation number (MADSON). Particle swarm optimization (PSO) is used to solve the corresponding mixed integer non...... that the proposed method can search a more promising control schedule of all transformers, all capacitors and all distributed generators with less time consumption, compared with other listed artificial intelligent methods....
Energy Technology Data Exchange (ETDEWEB)
Usami, Shin; Suzuki, Takayuki; Sasaki, Kenji; Deshimaru, Takehide [Power Reactor and Nuclear Fuel Development Corp., Tsuruga, Fukui (Japan). Monju Construction Office; Nakashima, Fumiaki
1996-09-01
In MONJU, reaction rate distribution measurements were made by foil activation methods from May through September 1994. On the basis of the reaction rate measurement data, the MONJU initial core breeding ratio and the power distribution, etc. were evaluated. As a result, the evaluated values and the calculated values showed good agreement, and we confirmed that the core performance of MONJU and the method of core calculations were satisfactory. (author)
Grid support by power electronic converters of distributed generation units
Morren, J.
2006-01-01
An increasing number of small Distributed Generation (DG) units are connected to the grid. The introduction of DG causes several problems, which are mainly related to the differences between DG units and conventional generators. Four problems have been considered in this thesis: damping of harmonics
Distributed Generation in Power Systems: An Overview and Key Issues
DEFF Research Database (Denmark)
Singh, Sri Niwas
2009-01-01
quality, etc. However, depending on the system configuration and management, these advantages may not be true. Moreover, due to structural and managerial changes in the electricity supply industry motivated with introduction of completion, the role of small generations distributed in the low...
Price-based control for electrical power distribution system
Jafarian, Matin; Scherpen, Jacquelien M.A.; Aiello, Marco; Carloni, Raffaella; Jeltsema, Dimitri; Lazar, Mircea
2016-01-01
In the coming years, the exploitation of Renewable Energy Sources (RES), i.e. wind and solar sources, will increase significantly. Comparing to fossil-fuel sources, RES are produced and distributed in a more decentralized fashion and their availability mainly depends on the climate and weather condi
Exploiting ancillary services from distributed generation - perspectives for the Danish power system
DEFF Research Database (Denmark)
Nyeng, Preben; Pedersen, Knud Ole Helgesen; Østergaard, Jacob
2007-01-01
The share of the electric power production originating from distributed energy resources has rapidly increased during the recent past. However when it comes to ancillary services necessary to ensure the stability and appropriate operation of the power system, the distributed energy resources take...... a very passive role. This paper outlines suggestions on how to activate the potential of ancillary services from distributed energy resources, thereby exploiting their ability to contribute to power system operation. Furthermore, methods for integrating the ancillary service delivery into a deregulated...
Development of Ada language control software for the NASA power management and distribution test bed
Wright, Ted; Mackin, Michael; Gantose, Dave
1989-01-01
The Ada language software developed to control the NASA Lewis Research Center's Power Management and Distribution testbed is described. The testbed is a reduced-scale prototype of the electric power system to be used on space station Freedom. It is designed to develop and test hardware and software for a 20-kHz power distribution system. The distributed, multiprocessor, testbed control system has an easy-to-use operator interface with an understandable English-text format. A simple interface for algorithm writers that uses the same commands as the operator interface is provided, encouraging interactive exploration of the system.
Ross, Nathan
2013-01-01
For a family of linear preferential attachment graphs, we provide rates of convergence for the total variation distance between the degree of a randomly chosen vertex and an appropriate power law distribution as the number of vertices tends to infinity. Our proof uses a new formulation of Stein's method for the negative binomial distribution, which stems from a distributional transformation that has the negative binomial distributions as the only fixed points.
网壳屋面杆件轴力在地震波下的动力响应分析%On Axial Force Distribution of Squsre Pyrsmid Grids Roof Attacked
Institute of Scientific and Technical Information of China (English)
袁光英
2012-01-01
Through project case, this paper discusses on axial force distribution of square pyramid space grids roof attacked by El-Centro seismic wave by dynamic response analysis, so as to be reference for design of square pyramid space grids structure and seismic research.%通过工程实例，采用线性动力时程分析法对网壳结构进行在El-centro地震波下的动力响应分析，得到了网壳屋面的轴力分布规律，为网壳结构的设计以及地震研究提供参考。
International organizations as a profession: Professional mobility and power distribution
Coicaud, Jean-Marc
2006-01-01
The role of international organizations grows with the acceleration of globalization and the increasing importance of global governance. However, thus far, only limited and rather narrow research has been generated on the subject. It is a state of affairs that reflects on international studies, as well as on the power realities of the world. By assessing international organizations through the career prospects that they offer to skilled professionals, this paper is an attempt to remedy this s...
Photovoltaic Power System and Power Distribution Demonstration for the Desert RATS Program
Colozza, Anthony; Jakupca, Ian; Mintz, Toby; Herlacher, Mike; Hussey, Sam
2012-01-01
A stand alone, mobile photovoltaic power system along with a cable deployment system was designed and constructed to take part in the Desert Research And Technology Studies (RATS) lunar surface human interaction evaluation program at Cinder Lake, Arizona. The power system consisted of a photovoltaic array/battery system. It is capable of providing 1 kW of electrical power. The system outputs were 48 V DC, 110 V AC, and 220 V AC. A cable reel with 200 m of power cable was used to provide power from the trailer to a remote location. The cable reel was installed on a small trailer. The reel was powered to provide low to no tension deployment of the cable. The cable was connected to the 220 V AC output of the power system trailer. The power was then converted back to 110 V AC on the cable deployment trailer for use at the remote site. The Scout lunar rover demonstration vehicle was used to tow the cable trailer and deploy the power cable. This deployment was performed under a number of operational scenarios, manned operation, remote operation and tele-robotically. Once deployed, the cable was used to provide power, from the power system trailer, to run various operational tasks at the remote location.
DEFF Research Database (Denmark)
Blaabjerg, Frede; Vilathgamuwa, D. M.; Loh, Poh Chiang;
2009-01-01
Distributed generation (DG) systems are usually connected to the grid using power electronic converters. Power delivered from such DG sources depends on factors like energy availability and load demand. The converters used in power conversion do not operate with their full capacity all the time......-stage buck-boost inverter, recently proposed Z-source inverter (ZSI) is a good candidate for future DG systems. This paper presents a controller design for a ZSI-based DG system to improve power quality of distribution systems. The proposed control method is tested with simulation results obtained using...
Energy Technology Data Exchange (ETDEWEB)
Castillo, A.; Torres, M.; Ortiz, J. J.; Perusquia, R.; Hernandez, J. L.; Montes, J. L. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)]. e-mail: jacm@nuclear.inin.mx
2008-07-01
In the present work the preliminary results were obtained with the zoctli system whose purpose is the axial design of assembly of nuclear fuel under certain considerations. For the mentioned design well-know cells were already used and that they have been proven in diverse cycles of operation in the nuclear power plant of Laguna Verde. The design contemplates fuels assemblies of 10x10 and with 2 water channels. The assembly was distributed in 6 axial zones according to its structure. In order to take to end the optimization is was used the well-known technique like Path relinking and to find the group of previous solutions required by this technique uses the technical Taboo search. In order to work with Path relinking, 5 trajectories was taken in to account from a set of 5 previous solutions generated with theTaboo search, the update of the group of solutions is carried out in dynamic form. In the case of the Taboo search it was used a list of variable size, it was implement an aspiration approach, it was used the vector of frequencies and due to the cost of the evaluation of the objective function, only it was review 5% of the vicinity. For the objective function was considered the limit thermal, the axial profile of power, the effective multiplication factor and the margin of having turned off in cold. In order to prove the design system, it was used a balance cycle with a value of reference of 0.9928 for the effective multiplication factor that is equivalent to a produced energy of 10896 MWd/TU at the end of operation to full power. The designed assemblies were placed both in one of lots different from fresh assemblies on which it counts the referred cycle. At the end one a comparison with the results obtained with other techniques and under similar conditions is made. The results obtained until the moment show an appropriate performance of the system. It is possible to indicate that a small inconvenient is the amount of consumed resources of calculation during
DEFF Research Database (Denmark)
Wu, Hongfei; Sun, Kai; Chen, Min;
2013-01-01
The unbalanced temperature distribution influences the power output of thermoelectric generator (TEG) system, which leads to mismatch power among TEG modules. This mismatch power degrades the energy efficiency of TEG systems based on the series-connected TEG modules. A hybrid centralized-distribu......The unbalanced temperature distribution influences the power output of thermoelectric generator (TEG) system, which leads to mismatch power among TEG modules. This mismatch power degrades the energy efficiency of TEG systems based on the series-connected TEG modules. A hybrid centralized...... the proposed system, which benefits for implementing high MPPT efficiency and high conversion efficiency simultaneously. A hybrid MPPT control strategy is proposed for this HCD power conditioning system. The characteristics, circuit implementation and operation principles of the proposed system are presented...
Stationarity of the inter-event power-law distributions
Gandica, Yerali; Aidos, Fernando Sampaio Dos; Lambiotte, Renaud; Carletti, and Timoteo
2016-01-01
A number of human activities exhibit a bursty pattern, namely periods of very high activity that are followed by rest periods. Records of these processes generate time series of events whose inter-event times follow a probability distribution that displays a fat tail. The grounds for such phenomenon are not yet clearly understood. In the present work we use the freely available Wikipedia editing records to unravel some features of this phenomenon. We show that even though the probability to start editing is conditioned by the circadian 24 hour cycle, the conditional probability for the time interval between successive edits at a given time of the day is independent from the latter. We confirm our findings with the activity of posting on the social network Twitter. Our result suggests there is an intrinsic humankind scheduling pattern: after overcoming the encumbrance to start an activity, there is a robust distribution of new related actions, which does not depend on the time of day.
Stationarity of the inter-event power-law distributions
Gandica, Yerali; Carvalho, Joao; Aidos, Fernando Sampaio Dos; Lambiotte, Renaud; Carletti, and Timoteo
2016-01-01
A number of human activities exhibit a bursty pattern, namely periods of very high activity that are followed by rest periods. Records of these processes generate time series of events whose inter-event times follow a probability distribution that displays a fat tail. The grounds for such phenomenon are not yet clearly understood. In the present work we use the freely available Wikipedia editing records to unravel some features of this phenomenon. We show that even though the probability to s...
Research on intelligent monitor for 3D power distribution of reactor core
International Nuclear Information System (INIS)
Highlights: • Core power distribution of ex-core measurement system has been reconstructed. • Building up an artificial intelligence model for 3-D core power distribution. • Error of the experiments has been reduced to 0.76%. • Methods for improving the accuracy of the model have been obtained. - Abstract: A real-time monitor for 3D reactor power distribution is critical for nuclear safety and high efficiency of NPP’s operation as well as for optimizing the control system, especially when the nuclear power plant (NPP) works at a certain power level or it works in load following operation. This paper was based on analyzing the monitor for 3D reactor power distribution technologies used in modern NPPs. Furthermore, considering the latest research outcomes, the paper proposed a method based on using an ex-core neutron detector system and a neural network to set up a real time monitor system for reactor’s 3D power distribution supervision. The results of the experiments performed on a reactor simulation machine illustrated that the new monitor system worked very well for a certain burn-up range during the fuel cycle. In addition, this new model could reduce the errors associated with the fitting of the distribution effectively, and several optimization methods were also obtained to improve the accuracy of the simulation model
Fast restoration of large area breakdown for power distribution systems
Institute of Scientific and Technical Information of China (English)
LIU Jian; XU Jing-qiu; CHENG Hong-li
2006-01-01
An adjacent table-based simplified model of distribution networks containing medium voltage buses of a substation is established.Identification of bus outage and the condition to start fast restoration procedure are discussed.A complex load shading parameter is set up to describe various load shading schemes.The imaginary part of the load shading parameter describes the states of switches of load shading schemes while the real part is the corresponding amount of shaded load.A new concept of independent tripping operation is also put forward.The procedure to search the operation with the least amount of shaded load for a feeder and a connected domain are detailed.The procedure for fast restoration of a large area breakdown of the whole distribution network under emergency states is dealt with using a typical grid distribution network as an example.Results of analysis show that the direct load shading scheme under the most balanced topology is not always the optimal scheme.The proposed method can obtain the optimal operating mode with the least amount of shaded load thus showing its feasibility.
Measurement of power density distribution and beam waist simulation for electron beam
International Nuclear Information System (INIS)
The study aims to measure the power density distribution of the electron beam (EB) for further estimating its characteristics. A compact device combining deflection signal controller and current signal acquisition circuit of the EB was built. A software modelling framework was developed to investigate structural parameters of the electron beam. With an iterative algorithm, the functional relationship between the electron beam power and its power density was solved and the corresponding contour map of power density distribution was plotted through isoline tracking approach. The power density distribution of various layers of cross-section beam was reconstructed for beam volume by direct volume rendering technique. The further simulation of beam waist with all-known marching cubes algorithm reveals the evolution of spatial appearance and geometry measurement principle was explained in detail. The study provides an evaluation of promising to replace the traditional idea of EB spatial characteristics. - Highlights: ► We build a framework for measuring power density distribution for electron beam. ► We capture actual electron and build transient spatial power distribution for EB. ► Tracing algorithm of power density contour for cross-section was designed. ► The volume and waist of the beam are reconstructed in 4D mode. ► Geometry measurement is finished which is befit for designing of process welding.
Energy Technology Data Exchange (ETDEWEB)
Moon, Sang Ki; Cho, Seok; Chun, Se Young; Park, Jong Kuk; Kim, Bok Deuk; Youn, Young Jung; Baek, Won Pil
2004-05-01
An experimental study of the Critical Heat Flux (CHF) has been performed for a water flow in a non-uniformly heated vertical 3x3 rod bundle under low flow and a wide range of pressure conditions. Since most of experimental studies on the low flow CHF have been performed under low pressure conditions, present study has investigated the effects of various parameters on the CHF under low flow and a wide range of pressure conditions. Especially, these experiments are focused on the CHF under Return-To-Power (RTP) conditions that are expected to occur in a main steam line break accident of Pressurized Water Reactors (PWRs). Using present CHF data, the applicability of conventional CHF correlations are investigated in a return-to-power condition. The CHF data have been collected for system pressures ranging from 0.47 to 15.06 MPa, mass flux from 49.66 to 654.44 kg/m{sup 2}s, inlet subcooling from 67.90 to 722.70 kJ/kg and exit quality from 0.36 to 1.29. In this study, the return-to-power conditions are defined as conditions with low mass flux less than 250 kg/m{sup 2}s, intermediated pressure between 6.0 MPa and 12.0 MPa, and high inlet subcooling greater than 200 kJ/kg. Total 299 CHF data including 93 CHF data in return-to-power conditions are obtained. The effects of various parameters on the CHF are consistent with previous understandings on the round tube CHF. Conventional CHF correlations predict the present return-to-power CHF data with reasonable accuracies. However, the prediction capabilities become worse in a very low mass flux below than about 100 kg/m{sup 2}s.
Grid Monitoring and Advanced Control of Distributed Power Generation Systems
DEFF Research Database (Denmark)
Timbus, Adrian Vasile
of controllers have been studied and compared. The possibility of using the information about grid variables into the control structure in order to improve the control of DPGS has also been investigated. As a consequence, improved behavior of resonant controller has been noticed if grid frequency information...... is forwarded to its internal model. Additionally, controllers such as dead beat and hysteresis controller improve their robustness to parameter mismatch if the identi ed value of grid impedance is passed to the controller. Moreover, several control strategies to provide exible active and reactive power control...
Electrical Load Forecasting in Power Distribution Network by Using Artificial Neural Network
Directory of Open Access Journals (Sweden)
Ali Nahari
2013-11-01
Full Text Available Today, one of most important concerns in electrical power markets and distribution network is supplying the customer demands. In order to manage the market it is necessary to forecast the usage of electrical power in distribution network. The pattern of electrical power usage depends on many different parameters such as the week days, seasons, weather condition and etc. Today, researchers by using an artificial intelligence based on the natural intelligence are trying to forecast the costumers’ usage of electrical power. In this Paper it is tried to forecast the electrical power usage according to weather data by using artificial neural network in Bushehr distribution electrical power network and also is tried to find out the pattern of electrical power usage with the dataset which is prepared by real data. The method which has been used here is useful in all kind of power forecasting such as short term, middle term and long term. It can be helpful to manage the distributed generators production schedule and also correction of electrical power usage.
AP1000® PWR reactor physics analysis with VERA-CS and KENO-VI. Part 2. Power distribution
International Nuclear Information System (INIS)
Westinghouse has applied the Core Simulator of the Virtual Environment for Reactor Applications, VERA-CS, under development by the Consortium for Advanced Simulation of LWRs (CASL) to the core physics analysis of the AP1000® PWR. The AP1000 PWR features an advanced first core with radial and axial heterogeneities, including enrichment zoning, multiple burnable absorbers, and a combination of light and heavy control banks to enable the MSHIMTM advanced operational strategy. These advanced features make application of VERA-CS to the AP1000 PWR first core especially relevant to qualify VERA performance. A companion paper at this conference describes the results obtained with VERA-CS and the KENO Monte-Carlo code for startup physics tests simulations of the AP1000 PWR first core (critical boron, rod worth and reactivity coefficients). This paper describes the results of detailed power distribution comparisons between VERA-CS and KENO, and confirms the excellent numerical agreement reported in the companion paper for the startup physics tests simulations. (author)
Directory of Open Access Journals (Sweden)
Ganiyu A. Ajenikoko
2014-01-01
Full Text Available Reliability indices are parametric quantities used to assess the performance levels of electrical power distribution systems. In this work, a generalized quadratic model is developed for electrical power distribution system contributions to system reliability indices using Ikeja, Port-Harcourt, Kaduna and Kano distribution system feeders as case studies. The mean System Average Interruption Duration Index (SAIDI, System Average Interruption Frequency Index (SAIFI and Customer Average Interruption Duration Index (CAIDI contributions to system reliability indices for Ikeja, Port-Harcourt, Kaduna and Kano distribution systems were 0.0033, 0.0026, 0.0033 and 0.0018 respectively due to the fact that a prolonged period of interruptions was recorded on most of the feeders attached to Port-Harcourt and Kano distribution systems making them to be less reliable compared to Ikeja and Kaduna distribution systems. The generalized Quadratic model forms a basis for a good design, planning and maintenance of distribution systems at large.
Yamaoki, Toshihiko; Hamada, Hiroaki; Matoba, Osamu
2016-09-01
Experimental investigation to show the effectiveness of the extraction method of absorber information in a scattering medium by taking the output power ratio distribution is presented. In the experiment, two metallic wires sandwiched by three homogeneous scattering media are used as absorbers in transmission geometry. The output power ratio distributions can extract the influence of the absorbers to enhance the optical signal. The peak position of the output power ratio distributions agree with the results suggested by numerical simulation. From the reconstructed results of tomography in the scattering media, we have confirmed that the tomographic image of two wires can distinguish them successfully from 41×21 output power ratio distributions by using continuous-wave light. PMID:27607261
Modelling the geographic distribution of wind power and the impact on transmission needs
DEFF Research Database (Denmark)
Østergaard, Poul Alberg
2003-01-01
Through energy systems modelling, transmission systems modelling and geographical modelling, the article examines the sensitivity of the response of the transmission system to the geographic distributions of wind power and in particular the sensitivity of the results to the accuracy...
Optimal Sizing and Placement of Power-to-Gas Systems in Future Active Distribution Networks
DEFF Research Database (Denmark)
Diaz de Cerio Mendaza, Iker; Bhattarai, Bishnu Prasad; Kouzelis, Konstantinos;
2015-01-01
Power-to-Gas is recently attracting lots of interest as a new alternative for the regulation of renewable based power system. In cases, where the re-powering of old wind turbines threatens the normal operation of the local distribution network, this becomes especially relevant. However, the design...... of medium voltage distribution networks does not normally follow a common pattern, finding a singular and very particular layouts in each case. This fact, makes the placement and dimensioning of such flexible loads a complicated task for the distribution system operator in the future. This paper describes...... -investment cost- and the technical losses in the system under study. The results obtained from the assessed test system show how such non-linear methods could help distribution system operators to obtain a fast and precise perception of what is the best way to integrate the Power-to-Gas facilities...
Digital control of grid connected converters for distributed power generation
Energy Technology Data Exchange (ETDEWEB)
Skjellnes, Tore
2008-07-01
Pulse width modulated converters are becoming increasingly popular as their cost decreases and power rating increases. The new trend of small scale power producers, often using renewable energy sources, has created new demands for delivery of energy to the grid. A major advantage of the pulse width modulated converter is the ability to control the output voltage at any point in the voltage period. This enables rapid response to load changes and non-linear loads. In addition it can shape the voltage in response to the output current to create an outward appearance of a source impedance. This is called a virtual impedance. This thesis presents a controller for a voltage controlled three phase pulse width modulated converter. This controller enables operation in standalone mode, in parallel with other converters in a micro grid, and in parallel with a strong main grid. A time varying virtual impedance is presented which mainly attenuates reactive currents. A method of investigating the overall impedance including the virtual impedance is presented. New net standards have been introduced, requiring the converter to operate even during severe dips in the grid voltage. Experiments are presented verifying the operation of the controller during voltage dips. (Author). 37 refs., 65 figs., 10 tabs
Voltage Control of Distribution Grids with Multi-Microgrids Using Reactive Power Management
Directory of Open Access Journals (Sweden)
WLODARCZYK, P.
2015-02-01
Full Text Available Low-voltage Microgrids can be valuable sources of ancillary services for the Distribution System Operators (DSOs. The aim of this paper was to study if and how multi-microgrids can contribute to Voltage Control (VC in medium-voltage distribution grids by means of reactive power generation and/or absorption. The hierarchical control strategy was proposed with the main focus on the tertiary control which was defined as optimal power flow problem. The interior-point algorithm was applied to optimise experimental benchmark grid with the presence of Distributed Energy Resources (DERs. Moreover, two primary objectives were formulated: active power losses and amount of reactive power used to reach the voltage profile. As a result the active power losses were minimised to the high extent achieving the savings around 22% during entire day.
Li, Cheng
Wind farms, photovoltaic arrays, fuel cells, and micro-turbines are all considered to be Distributed Generation (DG). DG is defined as the generation of power which is dispersed throughout a utility's service territory and either connected to the utility's distribution system or isolated in a small grid. This thesis addresses modeling and economic issues pertaining to the optimal reactive power planning for distribution system with wind power generation (WPG) units. Wind farms are inclined to cause reverse power flows and voltage variations due to the random-like outputs of wind turbines. To deal with this kind of problem caused by wide spread usage of wind power generation, this thesis investigates voltage and reactive power controls in such a distribution system. Consequently static capacitors (SC) and transformer taps are introduced into the system and treated as controllers. For the purpose of getting optimum voltage and realizing reactive power control, the research proposes a proper coordination among the controllers like on-load tap changer (OLTC), feeder-switched capacitors. What's more, in order to simulate its uncertainty, the wind power generation is modeled by the Markov model. In that way, calculating the probabilities for all the scenarios is possible. Some outputs with consecutive and discrete values have been used for transition between successive time states and within state wind speeds. The thesis will describe the method to generate the wind speed time series from the transition probability matrix. After that, utilizing genetic algorithm, the optimal locations of SCs, the sizes of SCs and transformer taps are determined so as to minimize the cost or minimize the power loss, and more importantly improve voltage profiles. The applicability of the proposed method is verified through simulation on a 9-bus system and a 30-bus system respectively. At last, the simulation results indicate that as long as the available capacitors are able to sufficiently
Method of compensating distribution of reactor burnup degree
International Nuclear Information System (INIS)
An object of the present invention is to attain an appropriate power distribution and a burnup degree distribution during an operation cycle, thereby improving the succeeding operation cycle in a BWR type reactor. That is, a deviation between a distribution of an actual axial burnup degree and that of an aimed axial burnup degree in a reactor core is measured upon completion of the operation cycle by using a burnup degree distribution measuring device. Then, the content of burnable poisons in fresh fuels to be charged to the reactor core is controlled in accordance with the deviation, to compensate the distribution of the axial burnup degree in the reactor core in the next operation cycle. Accordingly, the distribution of the axial burnup degree in the reactor core can be made closer to the aimed distribution of the burnup degree in the next operation cycle. Further, appropriate power distribution and a burnup degree distribution can be obtained by improving the axial power distribution in the reactor core with the characteristics of the fresh fuels themselves to be loaded, without depending only on changes of a control rod pattern. Accordingly, fuel economy and operation performance can be improved. (I.S.)
Custom DC-DC converters for distributing power in SLHC trackers
Allongue, B; Blanchot, G; Faccio, F; Fuentes, C; Mattavelli, P; Michelis, S; Orlandis, S; Spiazzi, G
2008-01-01
A power distribution scheme based on the use of on-board DC-DC converters is proposed to efficiently distribute power to the on-detector electronics of SLHC trackers. A comparative analysis of different promising converter topologies is presented, leading to the choice of a magneticbased buck converter as a first conversion stage followed by an on-chip switched capacitors converter. An overall efficiency above 80% is estimated for the practical implementation proposed.
Agent-based Distributed Unbalance Compensation for Optimal Power Quality in Islanded Microgrids
Meng, Lexuan; Dragicevic, Tomislav; Guerrero, Josep M.; Vasquez, Juan Carlos; Savaghebi, Mehdi; Tang, Fen
2014-01-01
In microgrids, the distributed generators (DG) can be used as distributed compensators so as to compensate the voltage unbalances in the critical bus. However, the power quality disturbance in generator sides and local buses may be affected and exceeds the limit. It can be more convenient to implement tertiary control so as to adjust the compensation efforts among DGs and ensure the acceptable power quality in local buses. Moreover, as centralized control methods have certain disadvantages, s...
Voltage control of distribution grids with multi-microgrids using reactive power management
Wlodarczyk, P.; Sumper, A.; CRUZ, M.
2015-01-01
Low-voltage Microgrids can be valuable sources of ancillary services for the Distribution System Operators (DSOs). The aim of this paper was to study if and how multi-microgrids can contribute to Voltage Control (VC) in medium-voltage distribution grids by means of reactive power generation and/or absorption. The hierarchical control strategy was proposed with the main focus on the tertiary control which was defined as optimal power flow problem. The interior-point algorithm w...
DC Distributed Power Systems - Analysis, Design and Control for a Renewable Energy System
Karlsson, Per
2002-01-01
Renewable energy systems are likely to become wide spread in the future due to environmental demands. As a consequence of the dispersed nature of renewable energy systems, this implies that there will be a distributed generation of electric power. Since most of the distributed electrical energy sources do not provide their electric power at line frequency and voltage, a DC bus is a useful common connection for several such sources. Due to the differences in output voltage among the sources, d...
Asymptotic distribution of singular values of powers of random matrices
Alexeev, Nikita; Tikhomirov, Alexander
2010-01-01
Let $x$ be a complex random variable such that ${\\E {x}=0}$, ${\\E |x|^2=1}$, ${\\E |x|^{4} < \\infty}$. Let $x_{ij}$, $i,j \\in \\{1,2,...\\}$ be independet copies of $x$. Let ${\\Xb=(N^{-1/2}x_{ij})}$, $1\\leq i,j \\leq N$ be a random matrix. Writing $\\Xb^*$ for the adjoint matrix of $\\Xb$, consider the product $\\Xb^m{\\Xb^*}^m$ with some $m \\in \\{1,2,...\\}$. The matrix $\\Xb^m{\\Xb^*}^m$ is Hermitian positive semi-definite. Let $\\lambda_1,\\lambda_2,...,\\lambda_N$ be eigenvalues of $\\Xb^m{\\Xb^*}^m$ (or squared singular values of the matrix $\\Xb^m$). In this paper we find the asymptotic distribution function \\[ G^{(m)}(x)=\\lim_{N\\to\\infty}\\E{F_N^{(m)}(x)} \\] of the empirical distribution function \\[ {F_N^{(m)}(x)} = N^{-1} \\sum_{k=1}^N {\\mathbb{I}{\\{\\lambda_k \\leq x\\}}}, \\] where $\\mathbb{I} \\{A\\}$ stands for the indicator function of event $A$. The moments of $G^{(m)}$ satisfy \\[ M^{(m)}_p=\\int_{\\mathbb{R}}{x^p dG^{(m)}(x)}=\\frac{1}{mp+1}\\binom{mp+p}{p}. \\] In Free Probability Theory $M^{(m)}_p$ are known as Fuss--C...
Power-law and exponential rank distributions: A panoramic Gibbsian perspective
Energy Technology Data Exchange (ETDEWEB)
Eliazar, Iddo, E-mail: eliazar@post.tau.ac.il
2015-04-15
Rank distributions are collections of positive sizes ordered either increasingly or decreasingly. Many decreasing rank distributions, formed by the collective collaboration of human actions, follow an inverse power-law relation between ranks and sizes. This remarkable empirical fact is termed Zipf’s law, and one of its quintessential manifestations is the demography of human settlements — which exhibits a harmonic relation between ranks and sizes. In this paper we present a comprehensive statistical-physics analysis of rank distributions, establish that power-law and exponential rank distributions stand out as optimal in various entropy-based senses, and unveil the special role of the harmonic relation between ranks and sizes. Our results extend the contemporary entropy-maximization view of Zipf’s law to a broader, panoramic, Gibbsian perspective of increasing and decreasing power-law and exponential rank distributions — of which Zipf’s law is one out of four pillars.
Zhao, Kai; Hui, Pan; Rao, Weixiong; Tarkoma, Sasu
2014-01-01
Human mobility has been empirically observed to exhibit Levy flight characteristics and behaviour with power-law distributed jump size. The fundamental mechanisms behind this behaviour has not yet been fully explained. In this paper, we analyze urban human mobility and we propose to explain the Levy walk behaviour observed in human mobility patterns by decomposing them into different classes according to the different transportation modes, such as Walk/Run, Bicycle, Train/Subway or Car/Taxi/Bus. Our analysis is based on two real-life GPS datasets containing approximately 10 and 20 million GPS samples with transportation mode information. We show that human mobility can be modelled as a mixture of different transportation modes, and that these single movement patterns can be approximated by a lognormal distribution rather than a power-law distribution. Then, we demonstrate that the mixture of the decomposed lognormal flight distributions associated with each modality is a power-law distribution, providing an e...
Distributed power control algorithm based on game theory for wireless sensor networks
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Energy saving is the most important issue in research and development for wireless sensor networks. A power control mechanism can reduce the power consumption of the whole network.Because the character of wireless sensor networks is restrictive energy,this paper proposes a distributed power control algorithm based on game theory for wireless sensor networks which objects of which are reducing power consumption and decreasing overhead and increasing network lifetime.The game theory and OPNET simulation shows that the power control algorithm converges to a Nash Equilibrium when decisions are updated according to a better response dynamic.
DEFF Research Database (Denmark)
Demirok, Erhan; Sera, Dezso; Teodorescu, Remus
2014-01-01
Grid-connected photovoltaic (PV) inverters tailored with reactive power management feature can support the grid voltage especially when the voltage fluctuates near its admissible limits. Although Q control allows reducing the grid voltage elevation along the distribution feeder, it brings extra...
DEFF Research Database (Denmark)
Hu, Weihao; Chen, Zhe; Bak-Jensen, Birgitte
2011-01-01
operation strategy for a Plug-In Electric Vehicle (PEV) in relation to the hourly electricity price in order to achieve minimum energy costs of the PEV. The western Danish power system, which is currently the grid area in the world that has the largest share of wind power in its generation profiles and may...... represent the future of electricity markets in some ways, is chosen as the studied power system in this paper. The impact of the optimal operation strategy for electric vehicles together with the optimal load response to spot market price on the distribution power system with high wind power penetrations...... are also discussed in the paper. Simulation results show that the proposed optimal operation strategy is an effective measure to achieve minimum energy costs of the PEV. The optimal operation strategy of the PEV and the optimal load response may have significant effects on the distribution power system...
Agamy, Mohammed; Elasser, Ahmed; Sabate, Juan Antonio; Galbraith, Anthony William; Harfman Todorovic, Maja
2014-09-09
A distributed photovoltaic (PV) power plant includes a plurality of distributed dc-dc converters. The dc-dc converters are configured to switch in coordination with one another such that at least one dc-dc converter transfers power to a common dc-bus based upon the total system power available from one or more corresponding strings of PV modules. Due to the coordinated switching of the dc-dc converters, each dc-dc converter transferring power to the common dc-bus continues to operate within its optimal efficiency range as well as to optimize the maximum power point tracking in order to increase the energy yield of the PV power plant.
Development of neural network for analysis of local power distributions in BWR fuel bundles
International Nuclear Information System (INIS)
A neural network model has been developed to learn the local power distributions in a BWR fuel bundle. A two layers neural network with total 128 elements is used for this model. The neural network learns 33 cases of local power peaking factors of fuel rods with given enrichment distribution as the teacher signals, which were calculated by a fuel bundle nuclear analysis code based on precise physical models. This neural network model studied well the teacher signals within 1 % error. It is also able to calculate the local power distributions within several % error for the different enrichment distributions from the teacher signals when the average enrichment is close to 2 %. This neural network is simple and the computing speed of this model is 300 times faster than that of the precise nuclear analysis code. This model was applied to survey the enrichment distribution to meet a target local power distribution in a fuel bundle, and the enrichment distribution with flat power shape are obtained within short computing time. (author)
Heskes, P.J.M.
2011-01-01
Today’s Distributed Generators (DG) and load appliances are increasingly build up with power electronics. This trend is expected to grow further in the future. Also developments are ongoing to improve the performance and efficiency of grid components by means of power electronics and several grid co
Design Methodology of High Power Distributed Amplifier Employing Broadband Impedance Transformer
DEFF Research Database (Denmark)
Narendra, Kumar; Zhurbenko, Vitaliy; Collantes, Juan Mari;
2009-01-01
A novel topology of a high power distributed amplifier (DA) in combination with a broadband impedance transformer is presented. The advantages of the proposed topology are explored analytically and verified by a full-wave 3D simulations. Stability of the high power DA is verified with the pole...
Submodule Integrated Distributed Maximum Power Point Tracking for Solar Photovoltaic Applications
Pilawa-Podgurski, Robert C. N.; Perreault, David J.
2012-01-01
This paper explores the benefits of distributed power electronics in solar photovoltaic applications through the use of submodule integrated maximum power point trackers (MPPT). We propose a system architecture that provides a substantial increase in captured energy during partial shading conditions, while at the same time enabling significant overall cost reductions. This is achieved through direct integration of miniature MPPT power converters into existing junction boxes. We describe the d...
Impact of Distributed Wind on Bulk Power System Operations in ISO-NE (Presentation)
Energy Technology Data Exchange (ETDEWEB)
Brancucci Martinez-Anido, C.; Hodge, B. M.; Palchak, D.; Miettinen, J.
2014-11-01
The work presented in the paper corresponding to this presentation aims to study the impact of a range of penetration levels of distributed wind on the operation of the electric power system at the transmission level. This presentation is an overview of a case study on the power system in Independent System Operator New England. It is analyzed using PLEXOS, a commercial power system simulation tool
Topić, Danijel; Šljivac, Damir; Gagro, Mirko
2015-01-01
The paper deals with the impact of renewable energy sources on reliability of distribution networks. It is determined through four case studies in which reliability indices are calculated. Island mode operation in the network is allowed with several assumptions. The authors assumed that the reliability of the system can be improved by islanded operation of distributed generation and showed an advantage of proposed islanding in relation to supply availability.
7 CFR 1717.857 - Refinancing of existing secured debt-distribution and power supply borrowers.
2010-01-01
... Private Financing § 1717.857 Refinancing of existing secured debt—distribution and power supply borrowers... 7 Agriculture 11 2010-01-01 2010-01-01 false Refinancing of existing secured debt-distribution and... of existing secured debt that meet the qualification criteria of this paragraph, except...
Allocation of Power Meters for Online Load Distribution Estimation in Smart Grids
DEFF Research Database (Denmark)
Kouzelis, Konstantinos; Diaz de Cerio Mendaza, Iker; Bak-Jensen, Birgitte;
2015-01-01
observability of the load distribution in their grid throughout the day. This paper investigates the possibility of improving the observability by allocating a minimum number of additional online operated power meters in the distribution grid. This allocation, driven by optimisation, clustering, and forecasting...
Institute of Scientific and Technical Information of China (English)
忻向军; 余重秀; 张茹; 任建华; 李安俭; 吴强; 辛雨; 王传林; 郑文潇; 阮双琛; 杜戈果; 辛港; 杨晓强
2003-01-01
The influence of channel power and pumping configuration on the gain profile of a distributed Raman fibre amplifier has been experimentally measured. The experimental results show that the influence is significant and should be considered during the gain flatness optimization of the distributed Raman fibre amplifier.
On renormalization of axial anomaly
International Nuclear Information System (INIS)
It is shown that multiplicative renormalization of the axial singlet current results in renormalization of the axial anomaly in all orders of perturbation theory. It is a necessary condition for the Adler - Bardeen theorem being valid. 10 refs.; 2 figs
Distributional effects of the fiscal impact of power plant siting
International Nuclear Information System (INIS)
Classical economic base analysis is grounded in the concept that export activity drives the local economy and that economic impacts due to development can be traced to changes in the export base. Local government activities are frequently treated as a consequence of economic change, but no significant economic impact has been associated with imported tax dollars. In this paper the siting of a power reactor is examined, and it is concluded that the major economic impact related to the siting may result from increases in the tax base, which permit either increased public expenditure or increased disposable income through tax rate decreases. It is argued that as the fraction of the tax base that is owned nonlocally increases, the community perceives a price change, since smaller amounts of local income must be foregone to purchase a constant level of public services. This relationship is estimated using a sample of rural counties drawn from the State of Tennessee. The empirical results generally support the importance of the price variable in determining discretionary expenditures out of local disposable incomes. This finding conforms to other results obtained through an examination of actual reactor sitings, and points to the importance of understanding community responses to increased tax base for understanding local economic impacts from reactor siting
Power law distribution of seismic rates: theory and data
Saichev, A
2004-01-01
We report an empirical determination of the probability density functions P(r) of the number r of earthquakes in finite space-time windows for the California catalog, over fixed spatial boxes 5 x 5 km^2 and time intervals dt =1, 10, 100 and 1000 days. We find a stable power law tail P(r) ~ 1/r^{1+mu} with exponent mu \\approx 1.6 for all time intervals. These observations are explained by a simple stochastic branching process previously studied by many authors, the ETAS (epidemic-type aftershock sequence) model which assumes that each earthquake can trigger other earthquakes (``aftershocks''). An aftershock sequence results in this model from the cascade of aftershocks of each past earthquake. We develop the full theory in terms of generating functions for describing the space-time organization of earthquake sequences and develop several approximations to solve the equations. The calibration of the theory to the empirical observations shows that it is essential to augment the ETAS model by taking account of th...
Axial instability of rotating relativistic stars
Friedman, J L; Friedman, John L.; Morsink, Sharon M.
1998-01-01
Perturbations of rotating relativistic stars can be classified by their behavior under parity. For axial perturbations (r-modes), initial data with negative canonical energy is found with angular dependence $e^{im\\phi}$ for all values of $m\\geq 2$ and for arbitrarily slow rotation. This implies instability (or marginal stability) of such perturbations for rotating perfect fluids. This low $m$-instability is strikingly different from the instability to polar perturbations, which sets in first for large values of $m$. The timescale for the axial instability appears, for small angular velocity $\\Omega$, to be proportional to a high power of $\\Omega$. As in the case of polar modes, viscosity will again presumably enforce stability except for hot, rapidly rotating neutron stars. This work complements Andersson's numerical investigation of axial modes in slowly rotating stars.
Advanced Power Conversion and Distribution - Efficient Power for JPL Spacecraft Project
National Aeronautics and Space Administration — We will develop a power conversion solution that will increase end-to-end efficiency to 80% or more compared to the 30%-50% efficiency typically obtained through...
Distributed Optimal Control of Reactive Power and Voltage in Islanded Microgrids
DEFF Research Database (Denmark)
Wang, Yanbo; Wang, Xiongfei; Chen, Zhe;
2016-01-01
The paper proposes a distributed optimal control strategy for islanded microgrids, which allows to perform reactive power sharing and voltage regulation without communication system. To realize the twofold objective, an improved small signal model is developed first to reconstruct the system input......-output relationship, where the relationship is evaluated with sensitivity analysis. A state estimator is then constructed based on the new input-output relationship in order to observe reactive power distribution and system voltages by local measurement. An optimal regulator is developed to perform both reactive...... the expected reliability and flexibility for optimizing the reactive power sharing and system voltages restoration....
DEFF Research Database (Denmark)
Hu, Weihao; Chen, Zhe; Bak-Jensen, Birgitte;
2014-01-01
power loss minimization in distribution systems. In this paper, a new method to achieve power loss minimization in distribution systems by using a price signal to guide the demand side management is proposed. A fuzzy adaptive particle swarm optimization (FAPSO) is used as a tool for the power loss......Consumers may decide to modify the profile of their demand from high price periods to low price periods in order to reduce their electricity costs. This optimal load response to electricity prices for demand side management generates different load profiles and provides an opportunity to achieve...
DEFF Research Database (Denmark)
Olsen, Rasmus Løvenstein; Hägerling, Christian; Kurtz, Fabian M.;
2014-01-01
The expected growth in distributed generation will significantly affect the operation and control of today’s distribution grids. Being confronted with short time power variations of distributed generations, the assurance of a reliable service (grid stability, avoidance of energy losses) and the q...... functionality is provided and a description of one of several use cases, the External Generation Site is detailed along its evaluation approach....
Energy Technology Data Exchange (ETDEWEB)
Costa, Danilo Leite
2013-07-01
This work aims to present a study about the power distribution behavior in a PWR type reactor, considering both intensity and migration of power peaks due to insertion of control rods into the core. Employing the multidimensional steady-state neutron diffusion equation in order to simulate the neutron flux, and using the Finite Difference Method. Furthermore, based on the axial power distribution on the largest heat flux rod, is carried out thermal analysis of this rod and associated coolant channel. For this purpose is employed the FueLRod{sub 3}D code, it uses the Finite Element Method to model the fuel rod and the associated coolant channel, allowing the thermohydraulics simulation of a single rod discretized in three dimensions, considering the heat flux from the pellet, crossing the gap and the cladding until it reaches the coolant. (author)
Khadkikar, Vinod
The present doctoral work is based on the philosophy of optimal utilization of the available resources in a most effective and efficient way to improve the product efficiency and to reduce the overall cost. This work proposes a novel control philosophy termed as power angle control (PAC), in which both the series and shunt inverters share the load reactive power in co-ordination with each other without affecting the basic UPQC compensation capabilities. This eventually results in a better utilization of the series inverter, reduction in the shunt inverter rating to some extent and ultimately in the reduction of the overall cost of UPQC. Moreover, in this thesis work several other control approaches are also proposed, such as, unit vector template generation, quadrature voltage injection, generalized single-phase p-q theory and novel current unbalance compensation approach. All the developed concepts are successfully validated through digital simulation as well as extensive experimental investigations. Keywords. power quality, active power filter, unified power quality conditioner, reactive power compensation, harmonics compensation.
Energy Technology Data Exchange (ETDEWEB)
NONE
2000-01-10
Hokuriku Electric Power Co., Inc., and Fuji Electric Co., Ltd., have jointly developed a personal computer system for automatic power distribution system backup which will monitor switches and perform independent operations in case of automatic power distribution system stoppage for example for inspection or maintenance. Under this system, backup operation is easily accomplished by switching the routine business personal computer from the in-house intranet to the automatic power distribution system LAN (local area network). The newly developed system is characterized by (1) its compatibility with a personal computer with Windows NT running thereon, (2) the downloading of data related to facilities that may be done via either intranet or automatic power distribution system, (3) its skeleton display of each power distribution line in the power distribution system chart, and (4) its capability of remote monitoring and control of pole equipment such as switches and SVR (step voltage regulator). (translated by NEDO)
Directory of Open Access Journals (Sweden)
Hamza Yapıcı
2016-06-01
Full Text Available In this paper the minimization of power losses in a real distribution network have been described by solving reactive power optimization problem. The optimization has been performed and tested on Konya Eregli Distribution Network in Turkey, a section of Turkish electric distribution network managed by MEDAŞ (Meram Electricity Distribution Corporation. The network contains about 9 feeders, 1323 buses (including 0.4 kV, 15.8 kV and 31.5 kV buses and 1311 transformers. This paper prefers a new Chaotic Firefly Algorithm (CFA and Particle Swarm Optimization (PSO for the power loss minimization in a real distribution network. The reactive power optimization problem is concluded with minimum active power losses by the optimal value of reactive power. The formulation contains detailed constraints including voltage limits and capacitor boundary. The simulation has been carried out with real data and results have been compared with Simulated Annealing (SA, standard Genetic Algorithm (SGA and standard Firefly Algorithm (FA. The proposed method has been found the better results than the other algorithms.
On-line test of power distribution prediction system for boiling water reactors
International Nuclear Information System (INIS)
A power distribution prediction system for boiling water reactors has been developed and its on-line performance test has proceeded at an operating commercial reactor. This system predicts the power distribution or thermal margin in advance of control rod operations and core flow rate change. This system consists of an on-line computer system, an operator's console with a color cathode-ray tube, and plant data input devices. The main functions of this system are present power distribution monitoring, power distribution prediction, and power-up trajectory prediction. The calculation method is based on a simplified nuclear thermal-hydraulic calculation, which is combined with a method of model identification to the actual reactor core state. It has been ascertained by the on-line test that the predicted power distribution (readings of traversing in-core probe) agrees with the measured data within 6% root-mean-square. The computing time required for one prediction calculation step is less than or equal to 1.5 min by an HIDIC-80 on-line computer
Directory of Open Access Journals (Sweden)
Wang Hao
2016-01-01
Full Text Available In current communication network for distribution in Chinese power grid systems, the fiber communication backbone network for distribution and TD-LTE power private wireless backhaul network of power grid are both bearing by the SDH optical transmission network, which also carries the communication network of transformer substation and main electric. As the data traffic of the distribution communication and TD-LTE power private wireless network grow rapidly in recent years, it will have a big impact with the SDH network’s bearing capacity which is mainly used for main electric communication in high security level. This paper presents a fusion networking model which use a multiple-layer PTN network as the unified bearing of the TD-LTE power private wireless backhaul network and fiber communication backbone network for distribution. Network dataflow analysis shows that this model can greatly reduce the capacity pressure of the traditional SDH network as well as ensure the reliability of the transmission of the communication network for distribution and TD-LTE power private wireless network.
Universal inverse power-law distribution for temperature and rainfall in the UK region
Selvam, A. M.
2014-06-01
Meteorological parameters, such as temperature, rainfall, pressure, etc., exhibit selfsimilar space-time fractal fluctuations generic to dynamical systems in nature such as fluid flows, spread of forest fires, earthquakes, etc. The power spectra of fractal fluctuations display inverse power-law form signifying long-range correlations. A general systems theory model predicts universal inverse power-law form incorporating the golden mean for the fractal fluctuations. The model predicted distribution was compared with observed distribution of fractal fluctuations of all size scales (small, large and extreme values) in the historic month-wise temperature (maximum and minimum) and total rainfall for the four stations Oxford, Armagh, Durham and Stornoway in the UK region, for data periods ranging from 92 years to 160 years. For each parameter, the two cumulative probability distributions, namely cmax and cmin starting from respectively maximum and minimum data value were used. The results of the study show that (i) temperature distributions (maximum and minimum) follow model predicted distribution except for Stornowy, minimum temperature cmin. (ii) Rainfall distribution for cmin follow model predicted distribution for all the four stations. (iii) Rainfall distribution for cmax follows model predicted distribution for the two stations Armagh and Stornoway. The present study suggests that fractal fluctuations result from the superimposition of eddy continuum fluctuations.
Study of Power Flow Algorithm of AC/DC Distribution System including VSC-MTDC
Directory of Open Access Journals (Sweden)
Haifeng Liang
2015-08-01
Full Text Available In recent years, distributed generation and a large number of sensitive AC and DC loads have been connected to distribution networks, which introduce a series of challenges to distribution network operators (DNOs. In addition, the advantages of DC distribution networks, such as the energy conservation and emission reduction, mean that the voltage source converter based multi-terminal direct current (VSC-MTDC for AC/DC distribution systems demonstrates a great potential, hence drawing growing research interest. In this paper, considering losses of the reactor, the filter and the converter, a mathematical model of VSC-HVDC for the load flow analysis is derived. An AC/DC distribution network architecture has been built, based on which the differences in modified equations of the VSC-MTDC-based network under different control modes are analyzed. In addition, corresponding interface functions under five control modes are provided, and a back/forward iterative algorithm which is applied to power flow calculation of the AC/DC distribution system including VSC-MTDC is proposed. Finally, by calculating the power flow of the modified IEEE14 AC/DC distribution network, the efficiency and validity of the model and algorithm are evaluated. With various distributed generations connected to the network at appropriate locations, power flow results show that network losses and utilization of transmission networks are effectively reduced.
DEFF Research Database (Denmark)
Knüppel, Thyge; Nielsen, Jørgen N.; Jensen, Kim H.;
2013-01-01
Wind power plants (WPP) are for power system stability studies often represented with aggregated models where several wind turbines (WT) are aggregated into a single up-scaled model. The advantage is a reduction in the model complexity and the computational time, and for a number of study types...... the accuracy of the results has been found acceptable. A large WPP is, however, both modular and distributed over a large geographical area, and feasibility of aggregating the WTs, thus, have to be reassessed when new applications are introduced for WPPs. Here, the power oscillation damping capabilities...... aggregation is investigated and it is shown that the level of WPP aggregation only has limited impact on the resulting modal damping. The study is based on a non-linear, dynamic model of the 3.6 MW Siemens Wind Power WT....
Mitigation of Output Power Fluctuations in Utility Grid using Three Phase Distribution Generation
Directory of Open Access Journals (Sweden)
K.Sri Chandan,
2010-12-01
Full Text Available Renewable electricity generation has never seen the level of investment and incentives that have been put in place by governments around the world during the last decade. However, despite the envisaged environmental and security of supply benefits that the harvesting of indigenous, renewable sources might bring about, their integration into the power system creates significant challenges to both the network operators and developers. The power quality challenges become even greater when large volumes of renewable generation capacity are connected to distribution networks, traditionally designed to be passive circuits with unidirectional power flows. This paper presents two schemes to meet the different power quality challenges in the utility grid due to Distribution Generation. In this first scheme is DSTATCOM and second is three phase Distributed Generation. This work is aimed at demonstrating, from the planning perspective, the benefits that the adoption of the different compensators might bring the system to a ‘fit and forget’ approach.
Improved margin utilization through the use of beacon power distribution surveillance
International Nuclear Information System (INIS)
Core Operations, including fuel cycle costs, can be significantly improved when state of the art surveillance techniques are employed for core power distribution monitoring. Core power distribution monitoring and Technical Specification surveillance are major operational issues at PWR's, particularly in plants with movable in core detectors. Even plants with fixed in core detectors do not always make use of the continuous data that is available. The BEACONTM system (Best Estimate Analysis of Core Operations - Nuclear) is a core monitoring and operational support package developed by Westinghouse for use in PWR plants with fixed or movable in core detectors. BEACON is a real time core monitoring system, which uses existing core instrumentation data and an on-line neutronics model to provide continuous monitored of the core power distribution information. With this information available the BEACON system can be used to continuously monitor core power margin for the plant Tech Spec surveillance requirements and for plant operational guidance
Hysteresis, Phase Transitions and Dangerous Transients in Electrical Power Distribution Systems
Duclut, Charlie; Chertkov, Michael
2012-01-01
The majority of dynamical studies in power systems focus on the high voltage transmission grids where models consider large generators interacting with crude aggregations of individual small loads. However, new phenomena have been observed indicating that the spatial distribution of collective, nonlinear contribution of these small loads in the low-voltage distribution grid is crucial to outcome of these dynamical transients. To elucidate the phenomenon, we study the dynamics of voltage and power flows in a spatially-extended distribution feeder (circuit) connecting many asynchronous induction motors and discover that this relatively simple 1+1 (space+time) dimensional system exhibits a plethora of nontrivial spatio-temporal effects, some of which may be dangerous for power system stability. Long-range motor-motor interactions mediated by circuit voltage and electrical power flows result in coexistence and segregation of spatially-extended phases defined by individual motor states--a "normal" state where the ...
Estimation of Power/Energy Losses in Electric Distribution Systems based on an Efficient Method
Directory of Open Access Journals (Sweden)
Gheorghe Grigoras
2013-09-01
Full Text Available Estimation of the power/energy losses constitutes an important tool for an efficient planning and operation of electric distribution systems, especially in a free energy market environment. For further development of plans of energy loss reduction and for determination of the implementation priorities of different measures and investment projects, analysis of the nature and reasons of losses in the system and in its different parts is needed. In the paper, an efficient method concerning the power flow problem of medium voltage distribution networks, under condition of lack of information about the nodal loads, is presented. Using this method it can obtain the power/energy losses in power transformers and the lines. The test results, obtained for a 20 kV real distribution network from Romania, confirmed the validity of the proposed method.
Barnes, P. R.; Vandyke, J. W.; Tesche, F. M.; Zaininger, H. W.
1994-06-01
Renewable energy technologies such as photovoltaic, solar thermal electricity, and wind turbine power are environmentally beneficial sources of electric power generation. The integration of renewable energy sources into electric power distribution systems can provide additional economic benefits because of a reduction in the losses associated with transmission and distribution lines. Benefits associated with the deferment of transmission and distribution investment may also be possible for cases where there is a high correlation between peak circuit load and renewable energy electric generation, such as photovoltaic systems in the Southwest. Case studies were conducted with actual power distribution system data for seven electric utilities with the participation of those utilities. Integrating renewable energy systems into electric power distribution systems increased the value of the benefits by about 20 to 55% above central station benefits in the national regional assessment. In the case studies presented in Vol. 2, the range was larger: from a few percent to near 80% for a case where costly investments were deferred. In general, additional savings of at least 10 to 20% can be expected by integrating at the distribution level. Wind energy systems were found to be economical in good wind resource regions, whereas photovoltaic systems costs are presently a factor of 2.5 too expensive under the most favorable conditions.
Efficiency Analyses of a DC Residential Power Distribution System for the Modern Home
Directory of Open Access Journals (Sweden)
GELANI, H. E.
2015-02-01
Full Text Available The electric power system started as DC back in the nineteenth century. However, the DC paradigm was soon ousted by AC due to inability of DC to change its voltage level. Now, after many years, with the development of power electronic converters capable of stepping-up and down DC voltage and converting it to-and-from AC, DC appears to be challenging AC and attempting a comeback. We now have DC power generation by solar cells, fuel cells and wind farms, DC power transmission in the form of HVDC (High Voltage DC transmission, DC power utilization by various modern electronic loads and DC power distribution that maybe regarded as still in research phase. This paper is an attempt to investigate feasibility of DC in the distribution portion of electrical power system. Specifically, the efficiency of a DC distribution system for residential localities is determined while keeping in view the concept of daily load variation. The aim is to bring out a more practical value of system efficiency as the efficiencies of DC/DC converters making up the system vary with load variation. This paper presents the modeling and simulation of a DC distribution system and efficiency results for various scenarios are presented.
The Real Powers of the Convolution of a Gamma Distribution and a Bernoulli Distribution
Nahla, Ben Salah; Afif, Masmoudi
2009-01-01
In this paper, we essentially compute the set of $x,y>0$ such that the mapping $z \\longmapsto \\Big{(}1-r+r e^z\\Big{)}^x \\Big{(}\\dis\\frac{\\lambda}{\\lambda-z}\\Big{)}^{y}$ is a Laplace transform. If $X$ and $Y$ are two independent random variables which have respectively Bernoulli and Gamma distributions, we denote by $\\mu$ the distribution of $X+Y.$ The above problem is equivalent to finding the set of $x>0$ such that $\\mu^{{\\ast}x}$ exists.
Impact of distributed and independent power generation on greenhouse gas emissions: Sri Lanka
Energy Technology Data Exchange (ETDEWEB)
Wijayatunga, P.D.C. [University of Moratuwa (Sri Lanka). Centre for Energy Studies; Fernando, W.J.L.S. [Sri Lanka Energy Managers Association, Colombo (Sri Lanka); Shrestha, R.M. [Asian Institute of Technology, Pathumthani (Thailand). Energy Program
2004-12-01
Sri Lanka has a hydropower dominated power system with approximately two thirds of its generation capacity based on large hydro plants. The remaining one third are based on oil fired thermal generation with varying technologies, such as oil steam, Diesel, gas turbines and combined cycle plants. A significant portion of this capacity is in operation as independent power plants (IPPs). In addition to these, Sri Lanka presently has about 40 MWs of mini-hydro plants, which are distributed in the highlands and their surrounding districts, mainly connected to the primary distribution system. Further, there are a few attempts to build fuel wood fired power plants of small capacities and connect them to the grid in various parts of the country. The study presented in this paper investigates the impact of these new developments in the power sector on the overall emissions and the greenhouse gas (GHG) emissions in particular. It examines the resulting changes to the emissions and costs in the event of developing the proposed coal power plant as an IPP under different investment and operational conditions. The paper also examines the impact on emissions with 80 MWs of distributed power in different capacities of wind, mini-hydro and wood fired power plants. It is concluded that grid connected, distributed power generation (DPG) reduces emissions, with only a marginal increase in overall costs, due to the reduction in transmission and distribution network losses that result from the distributed nature of generation. These reductions can be enhanced by opting for renewable energy based DPGS, as the case presented in the paper, and coupling them with demand side management measures. It is also concluded that there is no impact on overall emissions by the base load IPPs unless they are allowed to change over to different fuel types and technologies. (author)
Impact of distributed and independent power generation on greenhouse gas emissions: Sri Lanka
International Nuclear Information System (INIS)
Sri Lanka has a hydropower dominated power system with approximately two thirds of its generation capacity based on large hydro plants. The remaining one third are based on oil fired thermal generation with varying technologies, such as oil steam, Diesel, gas turbines and combined cycle plants. A significant portion of this capacity is in operation as independent power plants (IPPs). In addition to these, Sri Lanka presently has about 40 MWs of mini-hydro plants, which are distributed in the highlands and their surrounding districts, mainly connected to the primary distribution system. Further, there are a few attempts to build fuel wood fired power plants of small capacities and connect them to the grid in various parts of the country. The study presented in this paper investigates the impact of these new developments in the power sector on the overall emissions and the greenhouse gas (GHG) emissions in particular. It examines the resulting changes to the emissions and costs in the event of developing the proposed coal power plant as an IPP under different investment and operational conditions. The paper also examines the impact on emissions with 80 MWs of distributed power in different capacities of wind, mini-hydro and wood fired power plants. It is concluded that grid connected, distributed power generation (DPG) reduces emissions, with only a marginal increase in overall costs, due to the reduction in transmission and distribution network losses that result from the distributed nature of generation. These reductions can be enhanced by opting for renewable energy based DPGS, as the case presented in the paper, and coupling them with demand side management measures. It is also concluded that there is no impact on overall emissions by the base load IPPs unless they are allowed to change over to different fuel types and technologies. (author)
Directory of Open Access Journals (Sweden)
Wenpeng Yu
2013-12-01
Full Text Available Due to the interconnection and active management of Distributed Generation (DG and Energy Storage Systems (ESSs, the traditional electrical distribution network has become an Active Distribution Network (ADN, posing challenges to the operation optimization of the network. The power supply and storage capacity indexes of a Local Autonomy Control Region (LACR, which consists of DGs, ESSs and the network, are proposed in this paper to quantify the power regulating range of a LACR. DG/ESS and the network are considered as a whole in the model of the indexes, considering both network constraints and power constraints of the DG/ESS. The index quantifies the maximum LACR power supplied to or received from ADN lines. Similarly, power supply and storage capacity indexes of the ADN line are also proposed to quantify the maximum power exchanged between ADN lines. Then a practical algorithm to calculate the indexes is presented, and an operation optimization model is proposed based on the indexes to maximum the economic benefit of DG/ESS. In the optimization model, the power supply reliability of the ADN line is also considered. Finally, the indexes of power supply and storage capacity and the optimization are demonstrated in a case study.
Impact of Distributed Wind on Bulk Power System Operations in ISO-NE: Preprint
Energy Technology Data Exchange (ETDEWEB)
Brancucci Martinez-Anido, C.; Hodge, B. M.; Palchak, D.; Miettinen, J.
2014-09-01
The work presented in this paper aims to study the impact of a range of penetration levels of distributed wind on the operation of the electric power system at the transmission level. This paper presents a case study on the power system in Independent System Operator New England. It is analyzed using PLEXOS, a commercial power system simulation tool. The results show that increasing the integration of distributed wind reduces total variable electricity generation costs, coal- and gas-fired electricity generation, electricity imports, and CO2 emissions, and increases wind curtailment. The variability and uncertainty of wind power also increases the start-up and shutdown costs and ramping of most conventional power plants.
Control strategy for a distributed DC power system with renewable energy
Energy Technology Data Exchange (ETDEWEB)
Kurohane, Kyohei; Uehara, Akie; Senjyu, Tomonobu; Yona, Atsushi; Urasaki, Naomitsu [University of the Ryukyus, 1 Senbaru, Nishihara-cho, Nakagami, Okinawa 903-0213 (Japan); Funabashi, Toshihisa [Meidensha Corporation, 36-2 Nihonbashi-Hakozakicho, Chuo-ku, Tokyo 103-8513 (Japan); Kim, Chul-Hwan [Sungkyunkwan University and NPT Center, Suwon City 440-746 (Korea)
2011-01-15
This paper deals with a DC-micro-grid with renewable energy. The proposed method is composed of a gearless wind power generation system, a battery, and DC loads in a DC distribution system. The battery helps to avoid the DC over-voltages by absorbing the power of the permanent magnet synchronous generator (PMSG) during line-fault. In addition, the control schemes presented in this paper including the maximum power point tracking (MPPT) control and a pitch angle control for the gearless wind turbine generator. By means of the proposed method, high-reliable power can be supplied to the DC distribution system during the line-fault and stable power supply from the PMSG can be achieved after line-fault clearing. The effectiveness of the proposed method is examined in a MATLAB/Simulink {sup registered} environment. (author)
Power quality improvement in a PV distribution system by using D-STATCOM
Directory of Open Access Journals (Sweden)
P S V SUBRAHMANYAM
2013-12-01
Full Text Available In this paper one of the FACTS devices ie D-statcom is proposed to compensate the reactive power and unbalancing caused due to linear and non-linear loads in distribution system. It is very useful to rectify the power quality problems and to improve the voltage regulation and making system stable. When there is an integration of PV cell power to low voltage distribution grid, the voltage and frequency does not match each other in the network due to non linear loads. This paper presents modified instantaneous reactive power theory (IRP for calculation of instantaneous active and reactive power by transforming the 3-phase quantities to 2- phase quantities. The above scheme are analyzed under various operating conditions and the model performance is evaluate using MATLAB/SIMULINK software. These results are evaluated and the system effectiveness is established.
Spatial Distribution of Estimated Wind-Power Royalties in West Texas
Christian Brannstrom; Mary Tilton; Andrew Klein; Wendy Jepson
2015-01-01
Wind-power development in the U.S. occurs primarily on private land, producing royalties for landowners through private contracts with wind-farm operators. Texas, the U.S. leader in wind-power production with well-documented support for wind power, has virtually all of its ~12 GW of wind capacity sited on private lands. Determining the spatial distribution of royalty payments from wind energy is a crucial first step to understanding how renewable power may alter land-based livelihoods of some...
Energy Technology Data Exchange (ETDEWEB)
NONE
2004-07-01
This document gathers several models of contractual documents relative to the public distribution of electricity: grant conventions (for towns syndicate or for a single town), grant technical specifications (general dispositions, works relative to the granted network, services to users, tariffing, grant completion, various dispositions, local modalities between the granting authority and the grantee, third party participation to connection costs, electricity purchase and sale prices, general delivery conditions for low-power deliveries. (J.S.)
The Circulation Distribution on the Lifting Line for a Given Extracted Power
Directory of Open Access Journals (Sweden)
Ali Helali
2012-01-01
Full Text Available Presently, there exist few numerical methods which treat the inverse problem for the determination of the geometry of wind turbine blades. In this work, authors intend to solve the inverse optimum project for horizontal axis wind turbine in which the selection of the circulation distribution is obtained by resolving two variational problems: the first consists in sorting the circulation distribution on the lifting line, which, for a given power extracted by the wind turbine, minimizes the loses due to the induced velocity. In the second, the optimal circulation distribution is selected such that the kinetic energy of the wind downstream of the rotor disc is minimum, when the energy extracted by the wind turbine for one rotating period is imposed. A code has been developed which incorporates the real pitch of the helicoidal vortex wake. Very promising results have been obtained: the circulation distribution for a given extracted power and the chord lengths distribution law along the blade span.
The Principle of Power Distribution as a Factor of Democracy: Case Study
Directory of Open Access Journals (Sweden)
Kazimieras Monkevičius
2011-03-01
Full Text Available The principle of power distribution is directly connected with the theory of power distribution, which was first launched by the philosophers John Locke and Charles de Montesquieu. This principle was first established in democratic constitutions and soon became one of the main factors of the democratic development of countries. After the regaining of independence of Lithuania, the principle of power distribution was established in the Constitution of the Republic of Lithuania in 1992. Therefore, when analyzing the principle of power distribution as the aspect of democracy, one can take into account the Constitution of the Republic of Lithuania of 1992, which had a significant impact on the development of contemporary democratic Lithuania. The aim of this article is to reveal the rarely raised topic of the establishment of the principle of power distribution in the Constitution of the Republic of Lithuania of 1992, as well as to discuss its importance in the process of democratizing the independent country of Lithuania.
Electrical Market Management Considering Power System Constraints in Smart Distribution Grids
Directory of Open Access Journals (Sweden)
Poria Hasanpor Divshali
2016-05-01
Full Text Available Rising demand, climate change, growing fuel costs, outdated power system infrastructures, and new power generation technologies have made renewable distribution generators very attractive in recent years. Because of the increasing penetration level of renewable energy sources in addition to the growth of new electrical demand sectors, such as electrical vehicles, the power system may face serious problems and challenges in the near future. A revolutionary new power grid system, called smart grid, has been developed as a solution to these problems. The smart grid, equipped with modern communication and computation infrastructures, can coordinate different parts of the power system to enhance energy efficiency, reliability, and quality, while decreasing the energy cost. Since conventional distribution networks lack smart infrastructures, much research has been recently done in the distribution part of the smart grid, called smart distribution grid (SDG. This paper surveys contemporary literature in SDG from the perspective of the electricity market in addition to power system considerations. For this purpose, this paper reviews current demand side management methods, supply side management methods, and electrical vehicle charging and discharging techniques in SDG and also discusses their drawbacks. We also present future research directions to tackle new and existing challenges in the SDG.
Optimal configuration of power distribution of a research reactors by depleted uranium use
International Nuclear Information System (INIS)
A nuclear reactor project requires that the thermal power density distribution be as uniform as possible in order to minimize temperature peaks which limit the total power. This work describes the calculations aimed at determining an optimized distribution of depleted uranium in a graphite-moderated, air cooled cylindrical core loaded with natural uranium. Cross section calculations were performed with the Hammer code while 3D flux and power distributions were generated with the CITATION code. It has been found that the use of depleted uranium renders a more uniform flux and power distribution. The effect, which results from a decrease in the power density (and consequently, also in the temperature) in the hottest channels, allows the overall power to be further raised within the safety limits. In addition, the proposed method also provides a means to arbitrarily reduce the excess reactivity when necessary. Finally, it also leads to the creation of an over moderated region with higher thermal neutron fluxes which could be used for irradiation experiments. (author)
Evidence for Power-law tail of the Wealth Distribution in India
Sitabhra Sinha
2005-01-01
The higher-end tail of the wealth distribution in India is studied using recently published lists of the wealth of richest Indians between the years 2002-4. The resulting rank distribution seems to imply a power-law tail for the wealth distribution, with a Pareto exponent between 0.81 and 0.92 (depending on the year under analysis). This provides a comparison with previous studies of wealth distribution, which have all been confined to Western advanced capitalist economies. We conclude with a...
DEFF Research Database (Denmark)
Hu, Junjie; Yang, Guangya; Kok, Koen;
2016-01-01
The increasing number of distributed energy resources connected to power systems raises operational challenges for the network operator, such as introducing grid congestion and voltage deviations in the distribution network level, as well as increasing balancing needs at the whole system level....... Control and coordination of a large number of distributed energy assets requires innovative approaches. Transactive control has received much attention due to its decentralized decision-making and transparent characteristics. This paper introduces the concept and main features of transactive control...... by a high penetration of distributed energy resources....
DEFF Research Database (Denmark)
Lund, Torsten
2007-01-01
The paper presents an investigation of the active and reactive power losses in a distribution network with wind turbines and combined heat and power plants. The investigation is based on 15 min average power measurements and load flow calculations in the power system simulation tool PowerFactory...
Energy Technology Data Exchange (ETDEWEB)
Niknam, Taher; Meymand, Hamed Zeinoddini; Nayeripour, Majid [Electrical and Electronic Engineering Department, Shiraz University of Technology, Shiraz (Iran)
2010-08-15
Fuel cell power plants (FCPPs) have been taken into a great deal of consideration in recent years. The continuing growth of the power demand together with environmental constraints is increasing interest to use FCPPs in power system. Since FCPPs are usually connected to distribution network, the effect of FCPPs on distribution network is more than other sections of power system. One of the most important issues in distribution networks is optimal operation management (OOM) which can be affected by FCPPs. This paper proposes a new approach for optimal operation management of distribution networks including FCCPs. In the article, we consider the total electrical energy losses, the total electrical energy cost and the total emission as the objective functions which should be minimized. Whereas the optimal operation in distribution networks has a nonlinear mixed integer optimization problem, the optimal solution could be obtained through an evolutionary method. We use a new evolutionary algorithm based on Fuzzy Adaptive Particle Swarm Optimization (FAPSO) to solve the optimal operation problem and compare this method with Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Differential Evolution (DE), Ant Colony Optimization (ACO) and Tabu Search (TS) over two distribution test feeders. (author)
Directory of Open Access Journals (Sweden)
Mohammad Hosein Rezaei
2011-10-01
Full Text Available Transformers perform many functions such as voltage transformation, isolation and noise decoupling. They are indispensable components in electric power distribution system. However, at low frequencies (50 Hz, they are one of the heaviest and the most expensive equipment in an electrical distribution system. Nowadays, electronic power transformers are used instead of conventional power transformers that do voltage transformation and power delivery in power system by power electronic converter. In this paper, the structure of distribution electronic power transformer (DEPT are analized and then paid attention on the design of a linear-quadratic-regulator (LQR with integral action to improve dynamic performance of DEPT with voltage unbalance, voltage sags, voltage harmonics and voltage ﬂicker. The presentation control strategy is simulated by MATLAB/SIMULINK. In addition, the results that are in terms of dc-link reference voltage, input and output voltages clearly show that a better dynamic performance can be achieved by using the LQR method when compared to other techniques.
Space station electrical power distribution analysis using a load flow approach
Emanuel, Ervin M.
1987-01-01
The space station's electrical power system will evolve and grow in a manner much similar to the present terrestrial electrical power system utilities. The initial baseline reference configuration will contain more than 50 nodes or busses, inverters, transformers, overcurrent protection devices, distribution lines, solar arrays, and/or solar dynamic power generating sources. The system is designed to manage and distribute 75 KW of power single phase or three phase at 20 KHz, and grow to a level of 300 KW steady state, and must be capable of operating at a peak of 450 KW for 5 to 10 min. In order to plan far into the future and keep pace with load growth, a load flow power system analysis approach must be developed and utilized. This method is a well known energy assessment and management tool that is widely used throughout the Electrical Power Utility Industry. The results of a comprehensive evaluation and assessment of an Electrical Distribution System Analysis Program (EDSA) is discussed. Its potential use as an analysis and design tool for the 20 KHz space station electrical power system is addressed.
Energy Technology Data Exchange (ETDEWEB)
Kwang Y. Lee; Stuart S. Yin; Andre Boheman
2005-12-26
The objective of the proposed work is to develop an intelligent distributed fiber optical sensor system for real-time monitoring of high temperature in a boiler furnace in power plants. Of particular interest is the estimation of spatial and temporal distributions of high temperatures within a boiler furnace, which will be essential in assessing and controlling the mechanisms that form and remove pollutants at the source, such as NOx. The basic approach in developing the proposed sensor system is three fold: (1) development of high temperature distributed fiber optical sensor capable of measuring temperatures greater than 2000 C degree with spatial resolution of less than 1 cm; (2) development of distributed parameter system (DPS) models to map the three-dimensional (3D) temperature distribution for the furnace; and (3) development of an intelligent monitoring system for real-time monitoring of the 3D boiler temperature distribution. Under Task 1, we set up a dedicated high power, ultrafast laser system for fabricating in-fiber gratings in harsh environment optical fibers, successfully fabricated gratings in single crystal sapphire fibers by the high power laser system, and developed highly sensitive long period gratings (lpg) by electric arc. Under Task 2, relevant mathematical modeling studies of NOx formation in practical combustors. Studies show that in boiler systems with no swirl, the distributed temperature sensor may provide information sufficient to predict trends of NOx at the boiler exit. Under Task 3, we investigate a mathematical approach to extrapolation of the temperature distribution within a power plant boiler facility, using a combination of a modified neural network architecture and semigroup theory. The 3D temperature data is furnished by the Penn State Energy Institute using FLUENT. Given a set of empirical data with no analytic expression, we first develop an analytic description and then extend that model along a single axis. Extrapolation
Integrated Computing, Communication, and Distributed Control of Deregulated Electric Power Systems
Energy Technology Data Exchange (ETDEWEB)
Bajura, Richard; Feliachi, Ali
2008-09-24
Restructuring of the electricity market has affected all aspects of the power industry from generation to transmission, distribution, and consumption. Transmission circuits, in particular, are stressed often exceeding their stability limits because of the difficulty in building new transmission lines due to environmental concerns and financial risk. Deregulation has resulted in the need for tighter control strategies to maintain reliability even in the event of considerable structural changes, such as loss of a large generating unit or a transmission line, and changes in loading conditions due to the continuously varying power consumption. Our research efforts under the DOE EPSCoR Grant focused on Integrated Computing, Communication and Distributed Control of Deregulated Electric Power Systems. This research is applicable to operating and controlling modern electric energy systems. The controls developed by APERC provide for a more efficient, economical, reliable, and secure operation of these systems. Under this program, we developed distributed control algorithms suitable for large-scale geographically dispersed power systems and also economic tools to evaluate their effectiveness and impact on power markets. Progress was made in the development of distributed intelligent control agents for reliable and automated operation of integrated electric power systems. The methodologies employed combine information technology, control and communication, agent technology, and power systems engineering in the development of intelligent control agents for reliable and automated operation of integrated electric power systems. In the event of scheduled load changes or unforeseen disturbances, the power system is expected to minimize the effects and costs of disturbances and to maintain critical infrastructure operational.
Directory of Open Access Journals (Sweden)
Walt Wells
2008-01-01
Full Text Available Our objective in this paper is to solve a second order differential equation for a long, simply supported column member subjected to a lateral axial load using Heun's numerical method. We will use the solution to find the critical load at which the column member will fail due to buckling. We will calculate this load using Euler's derived analytical approach for an exact solution, as well as Euler's Numerical Method. We will then compare the three calculated values to see how much they deviate from one another. During the critical load calculation, it will be necessary to calculate the moment of inertia for the column member.
Pandey, Nisha; Sarswat, Prashant
2016-03-01
Energy plays a vital role in the socio -economic development, mainly due to the dependency of indispensable amenities on electricity. However, a matter of concern is developing country domestic power needs and inadequate supply. One of the cases is Indian subcontinent, where more than 50,000 villages still not have access to uninterrupted electric power. `Power theft' is a major challenge due to the lack of adequate energy supply and the financial constraints. Long distances, inaccurate and inflated electricity bills are the other issues lead to default on payments. Gram Power, a social enterprise, is providing a smart metering and affordable solution in areas where the extension of existing grid supply is economically not viable. India's first solar powered micro-grid (centralized array of solar panels) in Rajasthan was established by this initiative. The core innovation is a smart distribution technology that consists of smart meters with recharging facility and grid monitoring, to provide on-demand, theft-proof power through centralized servers with a pay-as-you-use schedule. The details of the changes, socio-economic transformation, and operational sustainability of such a community engagement model will be discussed in this study.
Directory of Open Access Journals (Sweden)
Sergio Saponara
2016-04-01
Full Text Available This work proposes a scalable architecture of an Uninterruptible Power Supply (UPS system, with predictive diagnosis capabilities, for safety critical applications. A Failure Mode and Effect Analysis (FMEA has identified the faults occurring in the energy storage unit, based on Valve Regulated Lead-Acid batteries, and in the 3-phase high power transformers, used in switching converters and for power isolation, as the main bottlenecks for power system reliability. To address these issues, a distributed network of measuring nodes is proposed, where vibration-based mechanical stress diagnosis is implemented together with electrical (voltage, current, impedance and thermal degradation analysis. Power system degradation is tracked through multi-channel measuring nodes with integrated digital signal processing in the transformed frequency domain, from 0.1 Hz to 1 kHz. Experimental measurements on real power systems for safety-critical applications validate the diagnostic unit.
Directory of Open Access Journals (Sweden)
J. L. Guardado
2014-01-01
Full Text Available Network reconfiguration is an alternative to reduce power losses and optimize the operation of power distribution systems. In this paper, an encoding scheme for evolutionary algorithms is proposed in order to search efficiently for the Pareto-optimal solutions during the reconfiguration of power distribution systems considering multiobjective optimization. The encoding scheme is based on the edge window decoder (EWD technique, which was embedded in the Strength Pareto Evolutionary Algorithm 2 (SPEA2 and the Nondominated Sorting Genetic Algorithm II (NSGA-II. The effectiveness of the encoding scheme was proved by solving a test problem for which the true Pareto-optimal solutions are known in advance. In order to prove the practicability of the encoding scheme, a real distribution system was used to find the near Pareto-optimal solutions for different objective functions to optimize.
On Origin of Power-Law Distributions in Self-Organized Criticality from Random Walk Treatment
Institute of Scientific and Technical Information of China (English)
CHANG Zhe; CAO Xiao-Feng; GUAN Cheng-Bo; DENG Zong-Wei; HUANG Chao-Guang; YANG Chun-Bin; LI Xin
2008-01-01
The origin of power-law distributions in self-organized criticality is investigated by treating the variation of the number of active sites in the system as a stochastic process. An avalanche is then regarded as a first-return random walk process in a one-dimensional lattice. We assume that the variation of the number of active sites has three possibilities in each update: to increase by 1 with probability fl, to decrease by 1 with probability f2, or remain unchanged with probability 1-f1-f2. This mimics the dynamics in the system. Power-law distributions of the lifetime are found when the random walk is unbiased with equal probability to move in opposite directions. This shows that power-law distributions in self-organized criticality may be caused by the balance of competitive interactions.
Alves, Luiz G A; Lenzi, Ervin K; Mendes, Renio S
2014-01-01
We report on the existing connection between power-law distributions and allometries. As it was first reported in [PLoS ONE 7, e40393 (2012)] for the relationship between homicides and population, when these urban indicators present asymptotic power-law distributions, they can also display specific allometries among themselves. Here, we present an extensive characterization of this connection when considering all possible pairs of relationships from twelve urban indicators of Brazilian cities (such as child labour, illiteracy, income, sanitation and unemployment). Our analysis reveal that all our urban indicators are asymptotically distributed as power laws and that the proposed connection also holds for our data when the allometric relationship displays enough correlations. We have also found that not all allometric relationships are independent and that they can be understood as a consequence of the allometric relationship between the urban indicator and the population size. We further show that the residua...
Modeling of unified power quality conditioner (UPQC) in distribution systems load flow
International Nuclear Information System (INIS)
This paper presents modeling of unified power quality conditioner (UPQC) in load flow calculations for steady-state voltage compensation. An accurate model for this device is derived to use in load flow calculations. The rating of this device as well as direction of reactive power injection required to compensate voltage to the desired value (1 p.u.) is derived and discussed analytically and mathematically using phasor diagram method. Since performance of the compensator varies when it reaches to its maximum capacity, modeling of UPQC in its maximum rating of reactive power injection is derived. The validity of the proposed model is examined using two standard distribution systems consisting of 33 and 69 nodes, respectively. The best location of UPQC for under voltage problem mitigation in the distribution network is determined. The results show the validity of the proposed model for UPQC in large distribution systems.
The Fair Distribution of Power to Electric Vehicles: An Alternative to Pricing
Zhou, Yingjie; Maxemchuk, Nicholas; Qian, Xiangying; Wang, Chen
2014-01-01
As the popularity of electric vehicles increases, the demand for more power can increase more rapidly than our ability to install additional generating capacity. In the long term we expect that the supply and demand will become balanced. However, in the interim the rate at which electric vehicles can be deployed will depend on our ability to charge these vehicles without inconveniencing their owners. In this paper, we investigate using fairness mechanisms to distribute power to electric vehic...
The Impact of Operators' Performance in the Reliability of Cyber-Physical Power Distribution Systems
Bessani, Michel; Fanucchi, Rodrigo Z.; Delbem, Alexandre C. C.; Carlos D. Maciel
2016-01-01
Cyber-Physical Systems are the result of integrating information and communication technologies into physical systems. One particular case are Cyber-Physical Power Systems (CPPS), which use communication technologies to perform real-time monitoring and operation. These kinds of systems have become more complex, impacting on the systems' characteristics, such as their reliability. In addition, it is already known that in terms of the reliability of Cyber-Physical Power Distribution Systems (CP...
Dynamics of modal power distribution in a multimode semiconductor laser with optical feedback
International Nuclear Information System (INIS)
The dynamics of power distribution between longitudinal modes of a multimode semiconductor laser subjected to external optical feedback is experimentally analysed in the low-frequency fluctuation regime. Power dropouts in the total light intensity are invariably accompanied by sudden activations of several longitudinal modes. These activations are seen not to be simultaneous to the dropouts, but to occur after them. The phenomenon is statistically analysed in a systematic way, and the corresponding delay is estimated. (letter to the editor)
Power law in the angular velocity distribution of a granular needle
Piasecki, J.; Viot, P.
2005-01-01
We show how inelastic collisions induce a power law with exponent -3 in the decay of the angular velocity distribution of anisotropic particles with sufficiently small moment of inertia. We investigate this question within the Boltzmann kinetic theory for an elongated granular particle immersed in a bath. The power law persists so long as the collisions are inelastic for a large range of angular velocities provided the mass ratio of the anisotropic particle and the bath particles remains smal...
A Dynamic Reactive Power Control for DFIG Wind Turbines and Its Impacts on Distribution Protections
Institute of Scientific and Technical Information of China (English)
2012-01-01
With the increasing penetration of distributed generations （DGs） into power grids, the fault ride-through ability of DG is attracting more and more attention. Recent grid codes require a DG to maintain its connection with the grid during grid faults and to play an active role in the recovery of grid voltage. This paper chooses the doubly- fed induction generator （DFIG） as the typical wind turbine for study. Firstly, a dynamic reactive power control strategy is proposed to improve the fault ride-through characteristic of a DFIG. The contributions of a DFIG to the fault current under the dynamic reactive power control and the Crowbar control are analyzed and compared based on the mathematical expressions and control behaviors. The impacts of a DFIG under two control strategies on distribution protections are discussed. Studies show that although a DFIG under the dynamic reactive power control provides more fault current component than one under the Crowbar control, its impacts on distribution protections are acceptable. Finally, a 10 kV distribution network with a DFIG is simulated in PowerFactory DIgSILENT. The simulation results prove the correctness of above theoretical analysis.
Power Management and Distribution Trades Studies for a Deep-Space Mission Scientific Spacecraft
Kimnach, Greg L.; Soltis, James V.
2004-01-01
As part of NASA's Project Prometheus, the Nuclear Systems Program, NASA GRC performed trade studies on the various Power Management and Distribution (PMAD) options for a deep-space scientific spacecraft which would have a nominal electrical power requirement of 100 kWe. These options included AC (1000Hz and 1500Hz and DC primary distribution at various voltages. The distribution system efficiency, reliability, mass, thermal, corona, space radiation levels and technology readiness of devices and components were considered. The final proposed system consisted of two independent power distribution channels, sourced by two 3-phase, 110 kVA alternators nominally operating at half-rated power. Each alternator nominally supplies 50kWe to one half of the ion thrusters and science modules but is capable of supplying the total power re3quirements in the event of loss of one alternator. This paper is an introduction to the methodology for the trades done to arrive at the proposed PMAD architecture. Any opinions expressed are those of the author(s) and do not necessarily reflect the views of Project Prometheus.
International Nuclear Information System (INIS)
Westinghouse has developed an advanced operational core support package called BEACON which uses a fully analytical methodology for on-line prediction of 3-D [three-dimensional] power distributions. The system provides core monitoring, core measurement reduction, core analysis and follow, and core predictions. The heart of the system is a very fast and accurate three dimensional nodal code which is used for core simulation and predictions. The system uses a new methodology with the existing core instrumentation to infer the current measured power distribution. This methodology has been qualified and yields excellent results
Power-law clique-degree distributions in real-life networks
Xiao, W K; Jin, H Y; Ren, J; Song, Z W; Wang, B H; Yang, H F; Zhou, T; Zhu, M X; Feng, Qi; Jin, Hui-Yu; Ren, Jie; Song, Zhi-Wei; Wang, Bing-Hong; Xiao, Wei-Ke; Yang, Hong-Feng; Zhou, Tao; Zhu, Meng-Xiao
2006-01-01
The community structure and motif-modular-network hiberarchy are of great importance for understanding the relationship between structures and functions. In this letter, we propose a new measure, the clique-degree, which is an extension of degree and can be used to measure the density of cliques in networks. The empirical studies indicate the extensive existence of power-law clique-degree distributions in various real networks. By comparing with the randomized networks, we show that the power-law clique-degree distribution is independent to traditional scale-free property.
Power profiling of Cholesky and QR factorizations on distributed memory systems
Bosilca, George
2012-08-30
This paper presents the power profile of two high performance dense linear algebra libraries on distributed memory systems, ScaLAPACK and DPLASMA. From the algorithmic perspective, their methodologies are opposite. The former is based on block algorithms and relies on multithreaded BLAS and a two-dimensional block cyclic data distribution to achieve high parallel performance. The latter is based on tile algorithms running on top of a tile data layout and uses fine-grained task parallelism combined with a dynamic distributed scheduler (DAGuE) to leverage distributed memory systems. We present performance results (Gflop/s) as well as the power profile (Watts) of two common dense factorizations needed to solve linear systems of equations, namely Cholesky and QR. The reported numbers show that DPLASMA surpasses ScaLAPACK not only in terms of performance (up to 2X speedup) but also in terms of energy efficiency (up to 62 %). © 2012 Springer-Verlag (outside the USA).
An automated system for studying the power distribution of electron beams
Energy Technology Data Exchange (ETDEWEB)
Filarowski, C.A.
1994-12-01
Precise welds with an electron beam welder are difficult to reproduce because the factors effecting the electron beam current density distribution are not easily controlled. One method for measuring the power density distribution in EB welds uses computer tomography to reconstruct an image of the current density distribution. This technique uses many separate pieces of hardware and software packages to obtain the data and then reconstruct it consequently, transferring this technology between different machines and operators is difficult. Consolidating all of the hardware and software into one machine to execute the same tasks will allow for real-time measurement of the EB power density distribution and will provide a facilitated means for transferring various welding procedure between different machines and operators, thereby enhancing reproducibility of electron beam welds.
A Power Load Distribution Algorithm to Optimize Data Center Electrical Flow
Directory of Open Access Journals (Sweden)
Paulo Maciel
2013-07-01
Full Text Available Energy consumption is a matter of common concern in the world today. Research demonstrates that as a consequence of the constantly evolving and expanding field of information technology, data centers are now major consumers of electrical energy. Such high electrical energy consumption emphasizes the issues of sustainability and cost. Against this background, the present paper proposes a power load distribution algorithm (PLDA to optimize energy distribution of data center power infrastructures. The PLDA, which is based on the Ford-Fulkerson algorithm, is supported by an environment called ASTRO, capable of performing the integrated evaluation of dependability, cost and sustainability. More specifically, the PLDA optimizes the flow distribution of the energy flow model (EFM. EFMs are responsible for estimating sustainability and cost issues of data center infrastructures without crossing the restrictions of the power capacity that each device can provide (power system or extract (cooling system. Additionally, a case study is presented that analyzed seven data center power architectures. Significant results were observed, achieving a reduction in power consumption of up to 15.5%.
Maximum entropy power laws: An application to the tail of wealth distribution
Milaković, Mishael
2002-01-01
Statistical equilibrium denotes the distribution of wealth that can be achieved in the largest number of ways while satisfying a first moment constraint on the rate of growth in wealth portfolios. Maximizing entropy subject to a logarithmic constraint yields a power law distribution whose characteristic exponent depends positively on the minimum wealth level, and inversely on the rate of growth and the average number of changes in the composition of wealth portfolios. Put differently, the dis...
IEEE 1588 synchronization in distributed measurement systems for electric power networks
Lixia, Marco
2012-01-01
Modern electric power systems can be considered as the consequence of the continuous technological evolution, often pushed by economical, political and social requirements. As an example, the main transformations in electric distribution systems arise from the diffusion of “Distributed Generation” (DG), i.e. small production plants, often supplied through renewable energy sources, whose presence has significant implications on both energy management (since “active networks” are needed to t...
Power scheduling of distributed estimation in sensor networks with repetition coding
Zhang, Li; Cui, Tao; Ho, Tracey; Zhang, Xian-Da
2010-01-01
This paper considers the optimal power scheduling for the distributed estimation of a source parameter using quantized samples of noisy sensor observations in a wireless sensor network (WSN). Repetition codes are used to transmit quantization bits of sensor observations to achieve unequal error protection, and a quasi-best linear unbiased estimate is constructed to estimate the source parameter at the fusion center (FC). Based on the adopted distributed estimation scheme (DES), we optimize th...
Wireless Information and Power Transfer Design for Energy Cooperation Distributed Antenna Systems
Yuan, Fangchao; Jin, Shi; Wong, Kai-Kit; Zhu, Hongbo
2016-01-01
Distributed antenna systems (DAS) have been widely implemented in state-of-the-art cellular communication systems to cover dead spots. Recent studies have also indicated that DAS have advantages in wireless energy transfer (WET). In this paper, we study simultaneous wireless information and power transfer (SWIPT) for a multiple-input single-output (MISO) DAS in the downlink which consists of arbitrarily distributed remote antenna units (RAUs). In order to save the energy cost, we adopt energy...
Energy Technology Data Exchange (ETDEWEB)
Kwang Y. Lee; Stuart S. Yin; Andre Boehman
2006-09-26
The objective of the proposed work is to develop an intelligent distributed fiber optical sensor system for real-time monitoring of high temperature in a boiler furnace in power plants. Of particular interest is the estimation of spatial and temporal distributions of high temperatures within a boiler furnace, which will be essential in assessing and controlling the mechanisms that form and remove pollutants at the source, such as NOx. The basic approach in developing the proposed sensor system is three fold: (1) development of high temperature distributed fiber optical sensor capable of measuring temperatures greater than 2000 C degree with spatial resolution of less than 1 cm; (2) development of distributed parameter system (DPS) models to map the three-dimensional (3D) temperature distribution for the furnace; and (3) development of an intelligent monitoring system for real-time monitoring of the 3D boiler temperature distribution. Under Task 1, we have set up a dedicated high power, ultrafast laser system for fabricating in-fiber gratings in harsh environment optical fibers, successfully fabricated gratings in single crystal sapphire fibers by the high power laser system, and developed highly sensitive long period gratings (lpg) by electric arc. Under Task 2, relevant mathematical modeling studies of NOx formation in practical combustors have been completed. Studies show that in boiler systems with no swirl, the distributed temperature sensor may provide information sufficient to predict trends of NOx at the boiler exit. Under Task 3, we have investigated a mathematical approach to extrapolation of the temperature distribution within a power plant boiler facility, using a combination of a modified neural network architecture and semigroup theory. Given a set of empirical data with no analytic expression, we first developed an analytic description and then extended that model along a single axis.
Directory of Open Access Journals (Sweden)
Babak Yousefi-Khangah
2014-12-01
Full Text Available If determination of location and size of Distributed Generation (DG are applied accurately, the DG’s ability will improve the network situation and reduce operation costs. In this paper, various market conditions are considered to maximize the benefit of DG’s presence and make a trade off among advantages of DG, network situation, and Distribution Company (DISCO owners. To determine the optimal location and size of DG, two methods of the cost minimization and the nodal pricing are combined. In addition to evaluating the impact of parameters such as variation of energy price and load on objective function, effect of these parameters on location and size of DG is considered. To confirm the results, impact of loads which are dependent on voltage and variation of the power factor of the DG units is applied and then effect of power factor on optimal location and size of DG is shown. A method is proposed for convergence of different results which is caused by different power factors. To observe long-term impact of the DG’s presence in the network, a load growth for five years is considered annually. Study is carried out on IEEE30 bus test circuit.
Renewable energy distributed power system with photovoltaic/ thermal and bio gas power generators
International Nuclear Information System (INIS)
The energy shortage and environmental pollution is becoming an important problem in these days. Hence it is very much important to use renewable power technologies to get rid of these problems. The important renewable energy sources are Bio-Energy, Wind Energy, Hydrogen Energy, Tide Energy, Terrestrial Heat Energy, Solar Energy, Thermal Energy and so on. Pakistan is rich in all these aspects particularly in Solar and Thermal Energies. In major areas of Pakistan like in South Punjab, Sind and Baluchistan the weather condition are very friendly for these types of Renewable Energies. In these areas Solar Energy can be utilized by solar panels in conjunction with thermal panels. The Photovoltaic cells are used to convert Solar Energy directly to Electrical Energy and thermal panels can be uses to convert solar energy into heat energy and this heat energy will be used to drive some turbine to get Electrical Energy. The Solar Energy can be absorbed more efficiently by any given area of Solar Panel if these two technologies can be combined in such a way that they can work together. The first part of this paper shows that how these technologies can be combined. Furthermore it is known to all that photovoltaic/thermal panels depend entirely on weather conditions. So in order to maintain constant power a biogas generator is used in conjunction with these. (author)
Directory of Open Access Journals (Sweden)
Gurrala Madhusudhan Rao
2014-10-01
Full Text Available Abstract: The main theme of the paper which deals with the enhancing steady-state and dynamics performance of the power grids by Flexible AC Transmission System (FACTS based on computational intelligence. The proposed technique will be applied to solve real problems in a power grid. The FACTS device, which will be used in the paper, is the most promising one, which known as the Distributed Power Flow Controller (DPFC. The paper achieves the optimization of the type, the location and the size of the power and control elements for DPFC to optimize the system performance. The paper derives the criteria to install the DPFC in an optimal location with optimal parameters and then designs an AI based damping controller for enhancing power system dynamic performance. In this paper, for every operating point genetic algorithm is used to search for controllers’ parameters, parameters found at certain operating point are different from those found at others. ANFISs are required in this case to recognize the appropriate parameters for each operating point.
Distributions of large-scale power outages : extreme values and the effect of truncation
Energy Technology Data Exchange (ETDEWEB)
Zeretzki, R.L. [Tenessee Univ., Knoxville, TN (United States). Dept. of Statistics; Briggs, W.M. [New York Methodist Hospital, Brooklyn, NY (United States); Sterling, M. [Oak Ridge Operations, Oak Ridge, TN (United States). Dept. of Energy; Shankar, M. [Oak Ridge National Laboratory, Oak Ridge, TN (United States). Computational Sciences
2009-07-01
Studies using complex systems theories have suggested that many power outages follow a power law distribution over certain time scales. In this study, a North American Electric Reliability Council (NERC) database was used to investigate the distribution of large-scale power outages between 1984 and 2006. The aim of the study was to statistically characterize the distribution of outages. Modern statistical methodologies were used to fit the data with various distributions. The statistical theory of extremes was then used to account for the truncation of smaller values in the reporting criteria. Results of the study were then used to investigate the risk management consequences of various tail behaviors. Techniques were developed to fit the actual distribution of the day including log-log rank plots and novel diagnostic plots. A central limit theorem was applied to the log of results in order to produce normalized data. The study showed that immediate investments to increase the reliability of the transmission and distribution network would be beneficial. 24 refs., 2 tabs., 6 figs.
Experimental studies of axial magnetic fields generated in ultrashort-pulse laser-plasma interaction
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
The quasistatic axial magnetic fields in plasmas produced by ultrashort laser pulses were measured by measuring the Faraday rotation angle of the backscattered emission. The spatial distribution of the axial magnetic field was obtained with a peak value as high as 170 Tesla. Theory suggests that the axial magnetic field is generated by dynamo effect in laser-plasma interaction.
Energy Technology Data Exchange (ETDEWEB)
Tamaki, K. [Okinawa Electric Power Co. Inc., Okinawa (Japan); Yamazaki, S.; Tabayashi, S.; Hirano, A. [Meidensha Corp., Tokyo (Japan)
1994-09-16
This paper introduces the summary of a computer control system for power distribution system automation used at Okinawa Electric Power Co., Inc. This system is intended to contribute to improvement of power supply reliability from a viewpoint of efficiency improvement and optimization of the system operation. The system performs automatic accommodating power distribution to healthy lines quickly during a power failure due to a distribution system failure or a planned power stoppage due to a system change, and incorporates functions characteristics to power distribution in Okinawa. The system features may be summarized as follows: a failure point is detected in a child station, and the failure point switch is released earlier than a distribution breaker is broken at the substation; therefore, only one failure occurs in the whole healthy line at an occurrence of the failure, and the failure point can be identified immediately by using a computer. Because the failure point is identified automatically from the earth fault current distribution in the failed distribution line, the failure point can be detected even after the line is reclosed successfully. The computer identifies the information on abnormality in the whole distribution line and analyzes it automatically, hence the abnormal distribution line and the abnormal point can be identified without occurring a power failure. 12 figs., 4 tabs.
Distributed control of hybrid AC microgrids with dynamic active and reactive power capacity tuning
DEFF Research Database (Denmark)
Nutkani, Inam Ullah; Loh, Poh Chiang; Blaabjerg, Frede
2012-01-01
power converters, whose control should preferably be done autonomously without demanding communication links. This paper proposes distributed control for power management between two Microgrids interlinked through inverters. The control scheme aims to reduce the reactive power loading stress on DERs and......Microgrids comprise of emerging generation technologies such as fuel cell, solar PV, wind turbine generator, storage and loads. They can, in principle, operate at different voltages and frequencies. Tying them either to the mains grid or among themselves would certainly require some interlinking...
Main Power Distribution Unit for the Jupiter Icy Moons Orbiter (JIMO)
Papa, Melissa R.
2004-01-01
Around the year 2011, the Jupiter Icy Moons Orbiter (JIMO) will be launched and on its way to orbit three of Jupiter s planet-sized moons. The mission goals for the JIMO project revolve heavily around gathering scientific data concerning ingredients we, as humans, consider essential: water, energy and necessary chemical elements. The JIM0 is an ambitious mission which will implore propulsion from an ION thruster powered by a nuclear fission reactor. Glenn Research Center is responsible for the development of the dynamic power conversion, power management and distribution, heat rejection and ION thrusters. The first test phase for the JIM0 program concerns the High Power AC Power Management and Distribution (PMAD) Test Bed. The goal of this testing is to support electrical performance verification of the power systems. The test bed will incorporate a 2kW Brayton Rotating Unit (BRU) to simulate the nuclear reactor as well as two ION thrusters. The first module of the PMAD Test Bed to be designed is the Main Power Distribution Unit (MPDU) which relays the power input to the various propulsion systems and scientific instruments. The MPDU involves circuitry design as well as mechanical design to determine the placement of the components. The MPDU consists of fourteen relays of four different variations used to convert the input power into the appropriate power output. The three phase system uses 400 Vo1ts(sub L-L) rms at 1000 Hertz. The power is relayed through the circuit and distributed to the scientific instruments, the ION thrusters and other controlled systems. The mechanical design requires the components to be positioned for easy electrical wiring as well as allowing adequate room for the main buss bars, individual circuit boards connected to each component and power supplies. To accomplish creating a suitable design, AutoCAD was used as a drafting tool. By showing a visual layout of the components, it is easy to see where there is extra room or where the
An Active Power Sharing Method among Distributed Energy Sources in an Islanded Series Micro-Grid
Directory of Open Access Journals (Sweden)
Wei-Man Yang
2014-11-01
Full Text Available Active power-sharing among distributed energy sources (DESs is not only an important way to realize optimal operation of micro-grids, but also the key to maintaining stability for islanded operation. Due to the unique configuration of series micro-grids (SMGs, the power-sharing method adopted in an ordinary AC, DC, and hybrid AC/DC system cannot be directly applied into SMGs. Power-sharing in one SMG with multiple DESs involves two aspects. On the one hand, capacitor voltage stability based on an energy storage system (ESS in the DC link must be complemented. Actually, this is a problem of power allocation between the generating unit and the ESS in the DES; an extensively researched, similar problem has been grid-off distributed power generation, for which there are good solutions. On the other hand, power-sharing among DESs should be considered to optimize the operation of a series micro-grid. In this paper, a novel method combining master control with auxiliary control is proposed. Master action of a quasi-proportional resonant controller is responsible for stability of the islanded SMG; auxiliary action based on state of charge (SOC realizes coordinated allocation of load power among the source. At the same time, it is important to ensure that the auxiliary control does not influence the master action.
Developing Virtual Power Plant for Optimized Distributed Energy Resources Operation and Integration
DEFF Research Database (Denmark)
You, Shi
of VPP, the Market-Based VPP (MBVPP) concept is proposed. The function-based MBVPP provides a generic and flexible solution for the DER integration by connecting the DER to the bulk power system operation via market participation. Two schemes for managing the DER generation and trading portfolios, direct......Distributed Energy Resources (DER) are small-scale power generation and storage technologies, (typically in the range of a few kWe to tens of kWe) located close to the customer side. They are right now under heavy development and have a great market potential in the near future. However...... units in the electric power system Efficient electricity market participation to benefit both power system operation and DER owners To address these issues, an innovative concept Virtual Power Plant (VPP) is investigated in this PhD study. Based on a comprehensive overview of the state of the art...
Directory of Open Access Journals (Sweden)
Qihong Chen
2014-01-01
Full Text Available This paper presents a neural network predictive control strategy to optimize power distribution for a fuel cell/ultracapacitor hybrid power system of a robot. We model the nonlinear power system by employing time variant auto-regressive moving average with exogenous (ARMAX, and using recurrent neural network to represent the complicated coefficients of the ARMAX model. Because the dynamic of the system is viewed as operating- state- dependent time varying local linear behavior in this frame, a linear constrained model predictive control algorithm is developed to optimize the power splitting between the fuel cell and ultracapacitor. The proposed algorithm significantly simplifies implementation of the controller and can handle multiple constraints, such as limiting substantial fluctuation of fuel cell current. Experiment and simulation results demonstrate that the control strategy can optimally split power between the fuel cell and ultracapacitor, limit the change rate of the fuel cell current, and so as to extend the lifetime of the fuel cell.
Chen, Qihong; Long, Rong; Quan, Shuhai; Zhang, Liyan
2014-01-01
This paper presents a neural network predictive control strategy to optimize power distribution for a fuel cell/ultracapacitor hybrid power system of a robot. We model the nonlinear power system by employing time variant auto-regressive moving average with exogenous (ARMAX), and using recurrent neural network to represent the complicated coefficients of the ARMAX model. Because the dynamic of the system is viewed as operating- state- dependent time varying local linear behavior in this frame, a linear constrained model predictive control algorithm is developed to optimize the power splitting between the fuel cell and ultracapacitor. The proposed algorithm significantly simplifies implementation of the controller and can handle multiple constraints, such as limiting substantial fluctuation of fuel cell current. Experiment and simulation results demonstrate that the control strategy can optimally split power between the fuel cell and ultracapacitor, limit the change rate of the fuel cell current, and so as to extend the lifetime of the fuel cell.
Considerations for decision-making on distributed power generation in rural areas
International Nuclear Information System (INIS)
Energy resources for rural electrification are variable and widely dispersed, such that a solution for one region might not be appropriate for another. This study evaluates the feasibility of renewable energy technologies, centralized grid extension and local coal-fired power for rural areas that currently do not have sufficient access to electricity. The renewable power generation options considered are solar photovoltaic and wind power, with battery storage or fossil fuel generator backup. New local coal-fired power, as well as extension of the grid from an existing centralized power system, are considered to compare the impacts of scale and traditional approaches to power generation. A case study for a rural area in Northwestern China demonstrates the complexity of energy decision-making when faced with low peak demands and non-ideal renewable resource availability. Economic factors, including cost of electricity generation, breakeven grid extension distance, capacity shortage fraction (the ratio of the annual capacity shortage to the annual electric load) and land use are evaluated. - Highlights: • Considerations include technical and non-technical factors for energy decisions. • Coal and renewable power are compared based on cost and availability of resources. • Key factors for renewable power generation are capacity shortage and availability of resources. • Rural China case study evaluates the viability of distributed wind or solar power relative to coal
DEFF Research Database (Denmark)
Faria, Pedro; Soares, Tiago; Vale, Zita;
2014-01-01
operators, utilities and consumers must adopt strategies and methods to take full advantage of demand response and distributed generation. This requires that all the involved players consider all the market opportunities, as the case of energy and reserve components of electricity markets. The present paper...... proposes a methodology which considers the joint dispatch of demand response and distributed generation in the context of a distribution network operated by a virtual power player. The resources’ participation can be performed in both energy and reserve contexts. This methodology contemplates...
Axial skeletal CT densitometry
International Nuclear Information System (INIS)
Since the discovery of the Roentgen ray a precise and accurate assessment of bone mineral content has been a challenge to many investigators. A number of methods have been developed but no one satisfied. Considering its technical possibilities computed tomography is very promising in determination of bone mineral content (BMC). The new modality enables BMC estimations in the axial skeletal trabecular bone. CT densitometry can be performed on a normal commercially available third generation whole body CT scanner. No dedicated device in a special clinical set-up is necessary. In this study 106 patients, most of them clinically suspected of osteoporosis, were examined. The new method CT densitometry has been evaluated. The results have been correlated to alternative BMC determination methods. (Auth.)
International Nuclear Information System (INIS)
Security and reliability are major concerns for future power systems with distributed generation. A comprehensive evaluation of the risk associated with these systems must consider contingencies under normal environmental conditions and also extreme ones. Environmental conditions can strongly influence the operation and performance of distributed generation systems, not only due to the growing shares of renewable-energy generators installed but also for the environment-related contingencies that can damage or deeply degrade the components of the power grid. In this context, the main novelty of this paper is the development of probabilistic risk assessment and risk-cost optimization framework for distributed power generation systems, that take the effects of extreme weather conditions into account. A Monte Carlo non-sequential algorithm is used for generating both normal and severe weather. The probabilistic risk assessment is embedded within a risk-based, bi-objective optimization to find the optimal size of generators distributed on the power grid that minimize both risks and cost associated with severe weather. An application is shown on a case study adapted from the IEEE 13 nodes test system. By comparing the results considering normal environmental conditions and the results considering the effects of extreme weather, the relevance of the latter clearly emerges. - Highlights: • Probabilistic risk assessed for distributed generation systems. • Extreme weather conditions are included in simulation and effects are quantified. • Risk based optimization to find optimal distributed generation sizes. • Distributed generation systems are confirmed less risky than the radial system. • Optimized DGs are less risky, especially considering extreme weather conditions
System-level power optimization for real-time distributed embedded systems
Luo, Jiong
Power optimization is one of the crucial design considerations for modern electronic systems. In this thesis, we present several system-level power optimization techniques for real-time distributed embedded systems, based on dynamic voltage scaling, dynamic power management, and management of peak power and variance of the power profile. Dynamic voltage scaling has been widely acknowledged as an important and powerful technique to trade off dynamic power consumption and delay. Efficient dynamic voltage scaling requires effective variable-voltage scheduling mechanisms that can adjust voltages and clock frequencies adaptively based on workloads and timing constraints. For this purpose, we propose static variable-voltage scheduling algorithms utilizing criticalpath driven timing analysis for the case when tasks are assumed to have uniform switching activities, as well as energy-gradient driven slack allocation for a more general scenario. The proposed techniques can achieve closeto-optimal power savings with very low computational complexity, without violating any real-time constraints. We also present algorithms for power-efficient joint scheduling of multi-rate periodic task graphs along with soft aperiodic tasks. The power issue is addressed through both dynamic voltage scaling and power management. Periodic task graphs are scheduled statically. Flexibility is introduced into the static schedule to allow the on-line scheduler to make local changes to PE schedules through resource reclaiming and slack stealing, without interfering with the validity of the global schedule. We provide a unified framework in which the response times of aperiodic tasks and power consumption are dynamically optimized simultaneously. Interconnection network fabrics point to a new generation of power-efficient and scalable interconnection architectures for distributed embedded systems. As the system bandwidth continues to increase, interconnection networks become power/energy limited as
Axial flux permanent magnet brushless machines
Gieras, Jacek F; Kamper, Maarten J
2008-01-01
Axial Flux Permanent Magnet (AFPM) brushless machines are modern electrical machines with a lot of advantages over their conventional counterparts. They are being increasingly used in consumer electronics, public life, instrumentation and automation system, clinical engineering, industrial electromechanical drives, automobile manufacturing industry, electric and hybrid electric vehicles, marine vessels and toys. They are also used in more electric aircrafts and many other applications on larger scale. New applications have also emerged in distributed generation systems (wind turbine generators
Power distribution control of CANDU reactors based on modal representation of reactor kinetics
Energy Technology Data Exchange (ETDEWEB)
Xia, Lingzhi, E-mail: lxia4@uwo.ca [Department of Electrical and Computer Engineering, The University of Western Ontario, London, Ontario N6A 5B9 (Canada); Jiang, Jin, E-mail: jjiang@eng.uwo.ca [Department of Electrical and Computer Engineering, The University of Western Ontario, London, Ontario N6A 5B9 (Canada); Luxat, John C., E-mail: luxatj@mcmaster.ca [Department of Engineering Physics, McMaster University, Hamilton, Ontario L8S 4L7 (Canada)
2014-10-15
Highlights: • Linearization of the modal synthesis model of neutronic kinetic equations for CANDU reactors. • Validation of the linearized dynamic model through closed-loop simulations by using the reactor regulating system. • Design of a LQR state feedback controller for CANDU core power distribution control. • Comparison of the results of this new controller against those of the conventional reactor regulation system. - Abstract: Modal synthesis representation of a neutronic kinetic model for a CANDU reactor core has been utilized in the analysis and synthesis for reactor control systems. Among all the mode shapes, the fundamental mode of the power distribution, which also coincides with the desired reactor power distribution during operation, is used in the control system design. The nonlinear modal models are linearized around desired operating points. Based on the linearized model, linear quadratic regulator (LQR) control approach is used to synthesize a state feedback controller. The performance of this controller has been evaluated by using the original nonlinear models under load-following conditions. It has been demonstrated that the proposed reactor control system can produce more uniform power distribution than the traditional reactor regulation systems (RRS); in particular, it is more effective in compensating the Xenon induced transients.