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1

High-frequency AC power distribution in Space Station  

Microsoft Academic Search

A utility-type, 20-kHz, AC power distribution system for the space station employing resonant power-conversion techniques is presented. The system converts raw DC voltage from photovoltaic cells or three-phase, low-frequency AC voltage from a solar dynamic generator into a regulated, 20-G kHz AC voltage for distribution among various loads. Operations of the components of the system such as driver inverter, DC

FU-SHENG TSAI; FRED C Y. LEE

1990-01-01

2

Modular power distribution system to drive DC and AC electrical loads, in particular for vehicle or domotics application  

US Patent & Trademark Office Database

A modular power distribution system configured to drive DC and AC electrical loads comprises logical units in different locations receiving DC and AC power lines for distribution to respectively DC and AC electrical loads in all of these locations. In each of the logical units, the system comprises one or more physical units, and in each of the physical units one or more power modules for the distribution of DC or AC power to one of the DC or AC electrical loads. Finally, the system comprises at least one master control unit for each of the logical units placed in one of physical units to control the functions of the pertaining logical unit.

2013-05-14

3

Power-Dense AC and DC Applications  

Microsoft Academic Search

This paper explores applications of the novel AC-link™ technology, a fundamentally different method of distributing and converting electrical power that is well suited to a wide variety of power distribution and Directed Energy Weapon (DEW) applications: DC-DC, AC-DC, or AC-AC. In particular, this paper will explore directed energy, load-leveling, and pulsed power applications and the advantages they gain from AC-

Rudy Limpaecher; Erik Limpaecher

4

Experimental development and evaluations of VF-input high-frequency AC-AC converter supporting distributed power generation  

Microsoft Academic Search

Presented is a novel variable-frequency input ac-ac converter that accepts a wide frequency variation of input raw power. The new converter and control offers a high-frequency control capability, at both input and output sides, that is a magnitude higher than the operating range reported so far in literature. The new converter is designed and experimentally implemented by novel three-in-one integrated

Jie Chang; Anhua Wang

2004-01-01

5

Mathematical Simulation of Power Conditioning Systems. Volume 4: Systems Simulation: Regulated Bus, AC Distribution, MPPT System Simulation Mathematique des Systemes de Conditionnement de Puissance. Simulation des Systemes. Barre Regulee, Distribution Alternative, Systeme Mppt.  

National Technical Information Service (NTIS)

Systems simulations are presented for the regulated bus concept, for the ac distribution system, and for the Maximum Power Point Tracking (MPPT) distribution system. Results show that the regulated bus system performs relatively well both for continuous a...

R. Prajoux J. Mazankine

1976-01-01

6

Evaluating alternatives for integrating distributed DC generation with AC power systems  

Microsoft Academic Search

Distributed generation generally means on site electric power generation devices such as photovoltaics or fuel cells that are installed at the customer end of the electric power system. One complication is that the photovoltaic panel and the fuel cell generate direct current (DC) while the electric power system and thus existing end use equipment has been designed for alternating current

F. Wicks

2000-01-01

7

Input power factor of ac to ac power converters  

NASA Astrophysics Data System (ADS)

AC to ac power converters are static systems using solid-state switching devices that directly convert ac power of a given frequency to ac power of some desired frequency. They are used to link ac power systems of different frequencies, to provide variable power frequency supplies for ac motor drives, and to generate constant frequency power from the output of variable-speed ac generators. The power conversion process requires the construction of output voltage waveforms, with the required frequency and amplitude, from the ac supply voltages given. The method of output waveform construction determines the input power factor of the ac to ac converter. The practical methods of output waveform construction are summarized and their effects on the input power factor are examined. The relationships between the output and input phase angles for differently controlled ac to ac converters are presented in graphical forms. It is shown that the input power factor of an ac to ac converter can be varied or kept at unity, without the use of passive reactive components, and independently of the output load.

Gyugyi, L.

1980-08-01

8

Control of Power Converters in AC Microgrids  

Microsoft Academic Search

The enabling of ac microgrids in distribution networks allows delivering distributed power and providing grid support services during regular operation of the grid, as well as powering isolated islands in case of faults and contingencies, thus increasing the performance and reliability of the electrical system. The high penetration of distributed generators, linked to the grid through highly controllable power processors

Joan Rocabert; Alvaro Luna; Frede Blaabjerg; Pedro Rodríguez

2012-01-01

9

Online monitoring of the distributed lateral displacement in large AC power generators using a high spatial resolution Brillouin optical fiber sensor  

NASA Astrophysics Data System (ADS)

We report for the first time, to the best of our knowledge, online monitoring of the distributed lateral displacement in large AC power generators using high spatial resolution differential pulse-width pair Brillouin optical time-domain analysis (DPP-BOTDA). To perform the measurement of distributed lateral displacements with periods of only a few cm in large AC power generators, a 2 cm spatial resolution strain measurement is realized using the differential pulse pair of 8/8.2 ns in DPP-BOTDA, and then the lateral displacements are reconstructed according to the strain-displacement relation with the assumption of a sine shape function. Using different fiberglass ripple springs, two types of lateral displacement with periods of 3 and 3.25 cm are demonstrated, obtaining a maximum displacement of 0.43 mm with a measurement accuracy of ~ 40 µm. This provides the information on the stator coil tightness through online monitoring of the distributed lateral displacement caused by the fiberglass ripple springs, and ensures safe operating conditions for large AC power generators. In addition, the large number of sensing points associated with distributed optical fiber sensors make it economically and technically practical to monitor large numbers of key components in a generator without any interference from the large magnetic and electrical fields.

Dong, Yongkang; Bao, Xiaoyi; Chen, Liang

2011-11-01

10

Optimized restoration of combined ac\\/dc shipboard power systems including distributed generation and islanding techniques  

Microsoft Academic Search

Reconfiguration involves changing the status (OFF\\/ON) of switches, and reconfiguration for restoration involves changing the switch status to maximize the supply to loads that are left unsupplied after fault removal. Shipboard Power Systems (SPS) need automated reconfiguration for restoration schemes to restore vital loads quickly and efficiently in order to improve fight-through and survivability capabilities. The restoration in this paper

Sarika Khushalani; Jignesh Solanki; Noel Schulz

2008-01-01

11

A Novel AC Uninterruptible Power Supply  

Microsoft Academic Search

This paper introduces a new ac Uninterruptible Power Supply (UPS) that has high efficiency, ac-input voltage regulation, and continuity of output power during any type of commercial ac-input power disturbance. These features are achieved in this UPS without the ac line-frequency energy storage components utilized in other UPSs to maintain output continuity during an ac-input power failure.

Farhad Barzegar; Michael J. Model

1987-01-01

12

AC versus DC distribution systems- Did we get it right?  

SciTech Connect

We presently enjoy a predominantly ac electrical distribution system, the engineering basis for which was designed over 100 years ago. While ac distribution systems have served us well, we should periodically pause to assess what opportunities we have accepted or been denied by the overwhelming predominance of ac electrical power distribution systems. What opportunities could be obtained by engineering dc distribution into at least portions of our present system? What advantages of the present ac distribution system should be recognized and protected? This paper will focus on distribution within premise and low-voltage distribution systems. Specifically, we will address the conversion efficiency costs of adopting various premise ac and dc distribution system topologies. According to a simple predictive model formulated in this paper, premise residential dc distribution will incur unfavorable total conversion efficiency compared with existing ac premise distribution. However, if a residence is supplied by a fuel cell or another dc generator, the total conversion efficiency within a residential dc distribution system could be similar to, or even better than, that for ac distribution.

Hammerstrom, Donald J.

2007-06-28

13

Semiconductor ac static power switch  

NASA Technical Reports Server (NTRS)

Semiconductor ac static power switch has long life and high reliability, contains no moving parts, and operates satisfactorily in severe environments, including high vibration and shock conditions. Due to their resistance to shock and vibration, static switches are used where accidental switching caused by mechanical vibration or shock cannot be tolerated.

Vrancik, J.

1968-01-01

14

AC Versus DC Distribution SystemsDid We Get it Right?  

Microsoft Academic Search

We presently enjoy a predominantly AC electrical distribution system, the engineering basis for which was designed over 100 years ago. While AC distribution systems have served us well, we should periodically pause to assess what opportunities we have accepted or been denied by the overwhelming predominance of AC electrical power distribution systems. What opportunities could be obtained by engineering DC

Donald J. Hammerstrom

2007-01-01

15

AC power system breadboard  

NASA Technical Reports Server (NTRS)

The object of this program was to design, build, test, and deliver a high-frequency (20-kHz) Power System Breadboard which would electrically approximate a pair of dual redundant power channels of an IOC Space Station. This report describes that program, including the technical background, and discusses the results, showing that the major assumptions about the characteristics of this class of hardware (size, mass, efficiency, control, etc.) were substantially correct. This testbed equipment has been completed and delivered to LeRC, where it is operating as a part of the Space Station Power System Test Facility.

Wappes, Loran J.; Sundberg, R.; Mildice, J.; Peterson, D.; Hushing, S.

1987-01-01

16

Distributed energy resources in grid interactive AC microgrids  

Microsoft Academic Search

Increased penetration of distributed energy resources (DER) and large-scale deployment of renewable energy sources are challenging the entire architecture of traditional power system. Microgrid, featuring higher flexibility and reliability, becomes an attractive candidate for the configuration of future electrical power system. This paper gives an overview of DER units in the grid interactive ac microgrid. The options in structures and

Xiongfei Wang; Josep M. Guerrero; Zhe Chen; Frede Blaabjerg

2010-01-01

17

21 CFR 886.1630 - AC-powered photostimulator.  

Code of Federal Regulations, 2010 CFR

...Devices § 886.1630 AC-powered photostimulator. (a) Identification. An AC-powered photostimulator is an AC-powered...intended to provide light stimulus which allows measurement of retinal or visual function by perceptual or electrical...

2009-04-01

18

Design note about a 75 KVA quiet power distribution system  

SciTech Connect

This note describes a 75KVA quiet power distribution system for X 653 in neutrino Lab D. It is fed from the regular AC distribution which exists in the building and it has no standby power. Its purpose is to remove electrical disturbances which are present on the regular AC distribution.

Visser, A.T.

1984-04-05

19

AC STRENGTH TEST DATA OF UNAGED AND WATER TANK AGED XLPE COMPOUNDS FOR TRANSMISSION AND DISTRIBUTION POWER CABLES  

Microsoft Academic Search

AC dielectric strength tests are performed on both virgin and water filled tank aged cable model specimens insulated with four commercial XLPE compounds in order to investigate the behaviour of such material under harsh wet environments. The results are compared in terms of Weibull scale and shape parameters. The degree of deterioration of aged compounds - measured in terms of

Massimo MARZINOTTO; Carlo MAZZETTI; Massimo POMPILI Prospero SCHIAFFINO

2007-01-01

20

AC-DC Power Processor, Type I.  

National Technical Information Service (NTIS)

The AC-DC Power Processor Type I Power Module furnishes O-100ADC over an output voltage range of 24 to 32VDC from a 120/208 30 50/60/400Hz power source. Remote output voltage sensing at the load circuit is provided to eliminate the IR drop of the power di...

J. J. Biess

1979-01-01

21

Power upgrading by simultaneous AC-DC power transfer in a double circuit AC line  

Microsoft Academic Search

Long EHV AC lines cannot be loaded to their thermal limits to keep sufficient margin against transient instability. With proposed simultaneous AC-DC transmission it is possible to load these line very close to their thermal limits. The conductors are allowed to carry superimposed DC current along with AC. The added DC power flow does not cause any transient instability. This

H. Rahman; B. H. Khan

2006-01-01

22

Combined Operation of AC and DC Distribution System with Distributed Generation Units  

NASA Astrophysics Data System (ADS)

This paper presents a DC distribution system which has been supplied by external AC systems as well as local DG units in order to demonstrate an overall solution to power quality issue. In this paper, the proposed operation method is demonstrated by simulation of power transfer between external AC systems, DG units, AC and DC loads. The power flow control in DC distribution system has been achieved by network converters and DG converters. Also, the mathematical model of the network, DG and load converters are obtained by using the average technique, which allows converter systems accurately simulated and control strategies for this converters is achieved. A suitable control strategy for network converters has been proposed that involves DC voltage droop regulator and novel instantaneous power regulation scheme. Also, a novel control technique has been proposed for DG converters. In this paper, a novel control system based on stationary and synchronously rotating reference frame has been proposed for load converters for supplying AC loads connected to the DC bus by balanced voltages. The several case studies have been studied based on proposed methods. The simulation results show that DC distribution systems including DG units can improve the power quality at the point of common coupling (PCC) in the power distribution system or industrial power system.

Noroozian, Reza; Abedi, Mehrdad; Gharehpetian, Gevorg

2010-07-01

23

Operation Method for AC Motor Control during Power Interruption in Direct AC/AC Converter System  

NASA Astrophysics Data System (ADS)

Direct AC/AC converters have been studied due to their potential use in power converters with no DC-link capacitor, which can contribute to the miniaturization of power converters. However, the absence of a DC-link capacitor makes it difficult to control the AC motor during power interruption. First, this paper proposes a system that realizes AC motor control during power interruption by utilizing a clamp capacitor. In general, direct AC/AC converters have a clamp circuit consisting of a rectifier diode(s) and a clamp capacitor in order to avoid over-voltages. In the proposed system, there is an additional semiconductor switch reverse-parallel to the rectifier diode(s), and the clamp capacitor voltage can be utilized for AC motor control by turning on the additional switch. Second, this paper discusses an operation method for AC motor control and clamp capacitor voltage control during power interruption. In the proposed method “DC-link voltage control”, the kinetic energy in the AC motor is transformed into electrical energy and stored in the clamp capacitor; the clamp capacitor is therefore charged and the capacitor voltage is controlled to remain constant at an instruction value. Third, this paper discusses a switching operation during power interruption. A dead-time is introduced between the operation of turning off all switches on the rectifier side and the operation of turning on the additional switch, which prevents the occurrence of a short circuit between the interrupted power source and the clamp capacitor. Finally, experimental results are presented. During power interruptions, an output current was continuously obtained and the clamp capacitor voltage was maintained to be equal to the instruction value of the capacitor voltage. These results indicate that both AC motor control and capacitor voltage control were successfully achieved by using the proposed system.

Shizu, Keiichiro; Azuma, Satoshi

24

A detailed RL fed bridge converter model for power flow studies in industrial AC\\/DC power systems  

Microsoft Academic Search

Because of lower voltage levels and smaller power ratings, the R\\/X ratio of commutation impedance in industrial AC\\/DC distribution systems is usually higher than that in HVDC transmission systems. Considerable discrepancies may therefore occur in industrial AC\\/DC power flow results, especially the reactive power consumption of converters, if the commutation resistances of the converters are neglected. To describe the effects

Yii-Shen Tzeng; Nanming Chen; Ruay-Nan Wu

1995-01-01

25

Measurements of AC Losses and Current Distribution in Superconducting Cables  

SciTech Connect

This paper presents our new experimental facility and techniques to measure ac loss and current distribution between the layers for High Temperature Superconducting (HTS) cables. The facility is powered with a 45 kVA three-phase power supply which can provide three-phase currents up to 5 kA per phase via high current transformers. The system is suitable for measurements at any frequency between 20 and 500 Hz to better understand the ac loss mechanisms in HTS cables. In this paper, we will report techniques and results for ac loss measurements carried out on several HTS cables with and without an HTS shielding layer. For cables without a shielding layer, care must be taken to control the effect of the magnetic fields from return currents on loss measurements. The waveform of the axial magnetic field was also measured by a small pick-up coil placed inside a two-layer cable. The temporal current distribution between the layers can be calculated from the waveform of the axial field.

Nguyen, Doan A [Los Alamos National Laboratory (LANL); Ashworth, Stephen P [Los Alamos National Laboratory (LANL); Duckworth, Robert C [ORNL; Carter, Bill [AMSC; Fleshler, Steven [AMER Superconductor Corp, Devens, MA 01434

2011-01-01

26

Automated power distribution system hardware. [for space station power supplies  

NASA Technical Reports Server (NTRS)

An automated power distribution system testbed for the space station common modules has been developed. It incorporates automated control and monitoring of a utility-type power system. Automated power system switchgear, control and sensor hardware requirements, hardware design, test results, and potential applications are discussed. The system is designed so that the automated control and monitoring of the power system is compatible with both a 208-V, 20-kHz single-phase AC system and a high-voltage (120 to 150 V) DC system.

Anderson, Paul M.; Martin, James A.; Thomason, Cindy

1989-01-01

27

The ac power system testbed  

NASA Technical Reports Server (NTRS)

The object of this program was to design, build, test, and deliver a high frequency (20 kHz) Power System Testbed which would electrically approximate a single, separable power channel of an IOC Space Station. That program is described, including the technical background, and the results are discussed showing that the major assumptions about the characteristics of this class of hardware (size, mass, efficiency, control, etc.) were substantially correct. This testbed equipment was completed and delivered and is being operated as part of the Space Station Power System Test Facility.

Mildice, J.; Sundberg, R.

1987-01-01

28

Power control for ac motor  

NASA Technical Reports Server (NTRS)

A motor controller employing a triac through which power is supplied to a motor is described. The open circuit voltage appearing across the triac controls the operation of a timing circuit. This timing circuit triggers on the triac at a time following turn off which varies inversely as a function of the amplitude of the open circuit voltage of the triac.

Dabney, R. W. (inventor)

1984-01-01

29

Multilevel converters for high power AC drives: a review  

Microsoft Academic Search

The multilevel approach appears to be very promising in AC motor drives, especially when both reduced harmonic contents and high power are required. Several topologies of multilevel voltage source power converters structures are presented and discussed, with particular reference to the modulation techniques which rule the power converters interfacing with the AC drives processes.

M. Marchesoni; M. Mazzucchelli

1993-01-01

30

High Power Electronics and flexible AC Transmission System  

Microsoft Academic Search

During the last decade, higher energy costs, the difficulty in building new power plants and improved converter technology provided an increased Market for HVDC transmission. However, HVDC, due to the high cost of converters, will play a limited role in the overall ac power system. The author discusses the potential of thyristors in ac power systems. The concept of a

N. G. Hingorani

1988-01-01

31

Automated Power-Distribution System  

NASA Technical Reports Server (NTRS)

Automated power-distribution system monitors and controls electrical power to modules in network. Handles both 208-V, 20-kHz single-phase alternating current and 120- to 150-V direct current. Power distributed to load modules from power-distribution control units (PDCU's) via subsystem distributors. Ring busses carry power to PDCU's from power source. Needs minimal attention. Detects faults and also protects against them. Potential applications include autonomous land vehicles and automated industrial process systems.

Thomason, Cindy; Anderson, Paul M.; Martin, James A.

1990-01-01

32

DC Voltage Control of the DC Micro-Grid for Super High Quality Electric Power Distribution  

Microsoft Academic Search

``DC Micro-grid'' is a novel power system using dc distribution in order to provide super high quality electric power. The power is distributed through dc distribution line and converted to required ac or dc voltages by converters placed near loads. The load side converters do not need transformers by choosing proper distributed dc voltage (±170V). The dc distribution line is

Hiroaki Kakigano; Yushi Miura; Toshifumi Ise; Ryohei Uchida

2007-01-01

33

Hybrid DC and AC-Linked Microgrids: Towards Integration of Distributed Energy Resources  

Microsoft Academic Search

This paper presents a microgrid paradigm with both DC and AC links, which may provide an effective way to integrate a heterogeneous set of small-size distributed energy resources into the existing electric power infrastructure. The collection of aggregated energy resource units at each level represents those distributed resources to the upper level as a single self-regulated entity (as a DC

Zhenhua Jiang; Xunwei Yu

2008-01-01

34

Automated Power-Distribution System  

NASA Technical Reports Server (NTRS)

Autonomous power-distribution system includes power-control equipment and automation equipment. System automatically schedules connection of power to loads and reconfigures itself when it detects fault. Potential terrestrial applications include optimization of consumption of power in homes, power supplies for autonomous land vehicles and vessels, and power supplies for automated industrial processes.

Ashworth, Barry; Riedesel, Joel; Myers, Chris; Miller, William; Jones, Ellen F.; Freeman, Kenneth; Walsh, Richard; Walls, Bryan K.; Weeks, David J.; Bechtel, Robert T.

1992-01-01

35

Improved power quality three phase AC-DC converter  

Microsoft Academic Search

Because of increasing applications of power electronic ac-dc converters, it's necessary to implement the single stage converter that can reliably perform both buck and boost operations. Traditionally, this can be achieved by double stage conversion (ac\\/dc-dc\\/dc) but ultimately leading to less efficiency and complex control. The novel ac-dc impedance-source converter, abbreviated as Z-source rectifier, has high power quality level and

Seyed Hossein Hosseini; F. Sedaghati; M. Sarhangzadeh

2010-01-01

36

Output power enhancement of ac Raman free-electron laser  

SciTech Connect

The ac free-electron laser (ac FEL) uses an ac (temporally oscillating but spatially uniform) field as the pump source with the hope that electromagnetic radiation will be produced with wavelength shorter than that can be generated by a conventional magnet FEL. The ac field can be provided by a superconducting cavity or by a plasma wave. In this note, the effects of the thermal motion of the electron beam on the linear gain and the nonlinear saturated output power in a Raman-regime ac FEL with the launch of an electromagnetic signal wave by particle-in-cell simulations are investigated. The output power enhancement of the ac FEL either by imposing an appropriate axial electric field at the time of radiation saturation or by properly tapering the strength or the frequency of the ac pump is discussed.

Yan, Y.T.

1987-01-01

37

Electrical Model of Balanced AC HTS Power Cable  

NASA Astrophysics Data System (ADS)

The future electricity grid will be more sustainable and it will have more power transmission and distribution capability with more electrical power added from decentralized sources on distribution level and from wind parks and other large sources on transmission level. More interconnections and more underground transmission and distribution will be put up. Use of high temperature superconducting (HTS) power cables provides solutions to many of the future grid problems caused by these trends. In this paper we present an electrical model of a balanced 6 km-long three phase triaxial HTS power cable for the Dutch project being developed by a consortium of Alliander, Ultera™ and TUD. The cable currents in all three phases are balanced by selecting proper twist pitches and insulation thickness. The paper focuses on determining inductances, capacitances and AC losses of the balanced cable. Using the developed model, we also determine the voltage drop as function of the cable length, the neutral current and the effect of the imbalanced capacitances on the current distribution of the Dutch distribution cable. The model is validated and it can be used for accurate simulation of the electrical behaviour of triaxial HTS cables in electrical grids.

Zuijderduin, R.; Chevtchenko, O.; Smit, J. J.; Willén, D.; Melnik, I.; Geschiere, A.

38

A hybrid electromechanical solid state switch for ac power control  

NASA Technical Reports Server (NTRS)

Bidirectional thyristor coupled to a series of actuator driven electromechanical contacts generates hybrid electromechanical solid state switch for ac power control. Device is useful in power control applications where zero crossover switching is required.

1972-01-01

39

Three-phase reactive power compensation using a single-phase AC\\/AC converter  

Microsoft Academic Search

A new control strategy and topology for VAr compensation is presented and analyzed. It treats a three-phase power system as two energy ports and uses one single-phase bidirectional AC\\/AC power converter to transfer reactive energy between the two ports to produce three-phase reactive power. The compensated reactive power can be leading or lagging. Hysteresis control is investigated as a means

Zhong Ye

1999-01-01

40

Stability enhancement of power system by controlling HVDC power flow through the same AC transmission line  

Microsoft Academic Search

HVDC power transmission employing power electronic device provides a wide range of control in power transmission. Remote generators are sometimes used to supply power to infinite bus through a single circuit long AC transmission line. The system may loose stability after the clearance of a fault if the pre-fault power transfer or the fault clearance time is high. Simultaneous AC-DC

K. P. Basu

2009-01-01

41

Distribution of AC loss in a HTS magnet for SMES with different operating conditions  

NASA Astrophysics Data System (ADS)

The AC loss induced in superconducting tape may affect the performance of a superconducting device applied to power system, such as transformer, cable, motor and even Superconducting Magnetic Energy Storage (SMES). The operating condition of SMES is changeable due to the need of compensation to the active or reactive power according to the demand of a power grid. In this paper, it is investigated that the distribution of AC loss for a storage magnet on different operating conditions, which is based on finite element method (FEM) and measured properties of BSCCO/Ag tapes. This analytical method can be used to optimize the SMES magnet.

Xu, Y.; Tang, Y.; Ren, L.; Jiao, F.; Song, M.; Cao, K.; Wang, D.; Wang, L.; Dong, H.

2013-11-01

42

SSP Power Management and Distribution  

NASA Technical Reports Server (NTRS)

Space Solar Power is a NASA program sponsored by Marshall Space Flight Center. The Paper presented here represents the architectural study of a large power management and distribution (PMAD) system. The PMAD supplies power to a microwave array for power beaming to an earth rectenna (Rectifier Antenna). The power is in the GW level.

Lynch, Thomas H.; Roth, A. (Technical Monitor)

2000-01-01

43

A probabilistic approach to optimizing power rating of interline power flow controllers in distributed generation power systems  

Microsoft Academic Search

High?power electronic converter topologies, in such forms as Unified Power Flow Controllers (UPFC), Static Compensators (STATCOM) and Interline Power Flow Controllers (IPFC), have been used to enhance and optimize the use of transmission facilities, under the concept of a flexible ac transmission system (FACTS). In Europe, the anticipated proliferation of distributed?generation (DG) in the near future, driven by governmental initiatives

Grzegorz Benysek

2007-01-01

44

AC\\/DC\\/AC high voltage traction drives with quasi-zero reactive power demand  

Microsoft Academic Search

A novel AC\\/DC\\/AC conversion structure has been developed, referring to single-phase AC (25 kV\\/50 Hz) traction systems using induction motor drives. High-voltage converters delivering multilevel voltage waveforms with lower harmonic content have been employed on both the line side and the motor side. High-performance techniques have been studied for controlling the whole system, assuring a quasi-unitary power factor and a

Sandro Bertini; Tommaso Ghiara; Mario Marchesoni

1993-01-01

45

Modeling of an AC Power System for High Power Spacecraft  

NASA Astrophysics Data System (ADS)

This paper presents an analysis and simulation of an AC power system for a high power spacecraft that primarily supplies rectified loads. Two different configurations consisting of a three-phase PM synchronous generator and an associated power electronics converter are compared and analyzed. The first configuration consists of a three-phase PM synchronous generator and a three-phase diode bridge supplying a DC load. The second configuration consists of a three-phase PM synchronous generator and a three-phase PWM rectifier supplying the DC load. The modeling equations for both systems are derived. The comparisons between the two different configurations are summarized in a table in terms of efficiency, harmonic content and DC voltage ripple. The simulation results obtained by using SIMULINK are presented.

Stankovic, A. V.; Birchenough, A. G.; Kenny, B.; Kimnach, G.

2004-02-01

46

Three-phase reactive power compensation using a single-phase AC\\/AC converter  

Microsoft Academic Search

A new control strategy and topology for VAr compensation is presented and analyzed. It treats a three-phase power system as two energy ports and uses one single-phase bidirectional AC\\/AC converter to transfer reactive energy between the two ports to produce three-phase reactive power. The compensated reactive power can be leading or lagging. Hysteresis control is investigated as a means of

Zhong Ye

1997-01-01

47

Modular structured multilevel inverter (MSMI) for high power AC power supply applications  

Microsoft Academic Search

Another main application of inverter systems in the industry is as AC power supplies, which include UPS systems and power conditioners for alternate\\/renewable sources of energy. The rapid development in information related industries and the inclination towards alternate\\/renewable sources of energy as future energy supply by power utilities have made an impact on the AC power supplies design which is

N. Ahmad Azli; A. H. M. Yatim

2001-01-01

48

Controlled power interface between solar cells and AC source  

Microsoft Academic Search

A novel interface circuit between solar cells and a commercial AC source using Van Allen's multivibrator is presented. In this circuit, the AC source is used as a backup for solar cells, and the source and load power flow is automatically balanced by the circuit itself without any external phase control. Based on the analysis of the characteristics of solar

Koosuke Harada; Gen Zhao

1993-01-01

49

A three-phase ac\\/ac power electronic transformer-based PWM ac drive with lossless commutation of leakage energy  

Microsoft Academic Search

This paper presents a novel three-phase ac\\/ac power converter topology with a high frequency ac-link for adjustable speed PWM ac drives. Such drives find applications in electric power generation from renewable energy sources like wind. This converter has a single power conversion stage with bidirectional power flow capability. The high frequency transformer provides voltage transformation, isolation, noise decoupling and high

Kaushik Basu; Apurva Somani; Krushna K Mohapatra; N. Mohan

2010-01-01

50

21 CFR 886.4440 - AC-powered magnet.  

Code of Federal Regulations, 2013 CFR

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES...is an AC-powered device that generates a magnetic field intended to find and remove metallic foreign bodies from eye tissue. (b)...

2013-04-01

51

21 CFR 886.4440 - AC-powered magnet.  

Code of Federal Regulations, 2010 CFR

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES...is an AC-powered device that generates a magnetic field intended to find and remove metallic foreign bodies from eye tissue. (b)...

2009-04-01

52

21 CFR 886.4440 - AC-powered magnet.  

Code of Federal Regulations, 2010 CFR

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES...is an AC-powered device that generates a magnetic field intended to find and remove metallic foreign bodies from eye tissue. (b)...

2010-04-01

53

High precision AC\\/AC power supply unit based on DSP controlled PWM inverter  

Microsoft Academic Search

The paper introduces a precision switching mode AC\\/AC power supply unit, that has been developed for calibration of current transformers. The device is fed by the 220 V 50\\/60 Hz mains, the output power is 3 kVA, and the output frequency is 50 or 60 Hz, which can be selected from the program. Large current control ratio, low level harmonic

T. Adam; I. Ajtonyi; F. Toth

2002-01-01

54

Reactive Power from Distributed Energy  

SciTech Connect

Distributed energy is an attractive option for solving reactive power and distribution system voltage problems because of its proximity to load. But the cost of retrofitting DE devices to absorb or produce reactive power needs to be reduced. There also needs to be a market mechanism in place for ISOs, RTOs, and transmission operators to procure reactive power from the customer side of the meter where DE usually resides. (author)

Kueck, John; Kirby, Brendan; Rizy, Tom; Li, Fangxing; Fall, Ndeye

2006-12-15

55

Main Injector power distribution system  

SciTech Connect

The paper describes a new power distribution system for Fermilab's Main Injector. The system provides 13.8 kV power to Main Injector accelerator (accelerator and conventional loads) and is capable of providing power to the rest of the laboratory (backfeed system). Design criteria, and features including simulation results are given.

Cezary Jach and Daniel Wolff

2002-06-03

56

Distributed Space Solar Power  

NASA Technical Reports Server (NTRS)

The objective was to assess the feasibility of safely collecting solar power at geostationary orbit and delivering it to earth. A strategy which could harness a small fraction of the millions of gigawatts of sunlight passing near earth could adequately supply the power needs of earth and those of space exploration far into the future. Light collected and enhanced both spatially and temporally in space and beamed to earth provides probably the only practical means of safe and efficient delivery of this space solar power to earth. In particular, we analyzed the feasibility of delivering power to sites on earth at a comparable intensity, after conversion to a usable form, to existing power needs. Two major obstacles in the delivery of space solar power to earth are safety and the development of a source suitable for space. We focused our approach on: (1) identifying system requirements and designing a strategy satisfying current eye and skin safety requirements; and (2) identifying a concept for a potential space-based source for producing the enhanced light.

Fork, Richard L.

2001-01-01

57

High power AC\\/DC converter and DC\\/AC inverter for high speed train applications  

Microsoft Academic Search

New developments in the design of high-speed electric trains are discussed, with particular reference to the induction motor drive system. A new high power three level converter-inverter system applying advanced insulated gate bipolar transistors (IGBTs) is described. Advanced control techniques lead to a unity power factor seen by the AC supply as well as minimising the line harmonics, power loss,

Adrian David Cheok; Shoichi Kawamoto; Takeo Matsumoto; Hideo Obi

2000-01-01

58

Power management and distribution technology  

NASA Technical Reports Server (NTRS)

Power management and distribution (PMAD) technology is discussed in the context of developing working systems for a piloted Mars nuclear electric propulsion (NEP) vehicle. The discussion is presented in vugraph form. The following topics are covered: applications and systems definitions; high performance components; the Civilian Space Technology Initiative (CSTI) high capacity power program; fiber optic sensors for power diagnostics; high temperature power electronics; 200 C baseplate electronics; high temperature component characterization; a high temperature coaxial transformer; and a silicon carbide mosfet.

Dickman, John Ellis

1993-01-01

59

Power factor control system for AC induction motors  

NASA Technical Reports Server (NTRS)

A power factor control system for use with ac induction motors was designed which samples lines voltage and current through the motor and decreases power input to the motor proportional to the detected phase displacement between current and voltage. This system provides, less power to the motor, as it is less loaded.

Nola, F. J. (inventor)

1977-01-01

60

Implementation of three-level AC\\/DC\\/AC converter with power factor correction and harmonic reduction  

Microsoft Academic Search

This paper proposes a three-level AC\\/DC\\/AC converter. A single-phase double-voltage power factor correction circuit to improve the power quality and provide two capacitor voltages in the input side of the AC\\/DC\\/AC converter and a three-level PWM inverter to reduce the harmonic contents of the inverter output voltages for induction motor drive are presented. In the rectifier side, the hysteresis current

Bor-Ren Lin; Hsin-Hung Lu; Yaow-Ming Chen

1998-01-01

61

AC/DC Power Systems with Applications for future Lunar/Mars base and Crew Exploration Vehicle  

NASA Technical Reports Server (NTRS)

ABSTRACT The Power Systems branch at JSC faces a number of complex issues as it readies itself for the President's initiative on future space exploration beyond low earth orbit. Some of these preliminary issues - those dealing with electric power generation and distribution on board Mars-bound vehicle and that on Lunar and Martian surface may be summarized as follows: Type of prime mover - Because solar power may not be readily available on parts of the Lunar/Mars surface and also during the long duration flight to Mars, the primary source of power will most likely be nuclear power (Uranium fuel rods) with a secondary source of fuel cell (Hydrogen supply). The electric power generation source - With nuclear power being the main prime mover, the electric power generation source will most likely be an ac generator at a yet to be determined frequency. Thus, a critical issue is whether the generator should generate at constant or variable frequency. This will decide what type of generator to use - whether it is a synchronous machine, an asynchronous induction machine or a switched reluctance machine. The type of power distribution system - the distribution frequency, number of wires (3- wire, 4-wire or higher), and ac/dc hybridization. Building redundancy and fault tolerance in the generation and distribution sub-systems so that the system is safe; provides 100% availability to critical loads; continues to operate even with faulted sub-systems; and requires minimal maintenance. This report descril_es results of a summer faculty fellowship spent in the Power Systems Branch with the specific aim of investigating some of the lessons learned in electric power generation and usage from the terrestrial power systems industry, the aerospace industry as well as NASA's on-going missions so as to recommend novel surface and vehicle-based power systems architectures in support of future space exploration initiatives. A hybrid ac/dc architecture with source side and load side redundancies and including emergency generators on both ac and dc sides is proposed. The generation frequency is 400 Hz mostly because of the technology maturity at this frequency in the aerospace industry. Power will be distributed to several ac load distribution buses through solid state variable speed, constant frequency converters on the ac side. A segmented dc ring bus supplied from ac/dc converters and with the capability of connecting/disconnecting the segments will supply power to multiple de load distribution buses. The system will have the capability of reverse flow from dc to ac side in the case of an extreme emergency on the main ac generation side.

Chowdhury, Badrul H.

2005-01-01

62

High power clean DC bus generation using AC-link AC to DC power voltage conversion, DC regulation, and galvanic isolation  

Microsoft Academic Search

The proliferation of large non linear loads such as main propulsion and thruster variable frequency drives (VFDs) on both warships and commercial vessels, high voltage power supplies for lasers and other advanced weapons on warships require both AC voltage transformation and power conversion from AC to DC. For VFDs, rectification from AC to DC and inversion from DC back to

Ian C Evans; Rudy Limpaecher

2009-01-01

63

Performance Comparison of High Frequency Isolated AC-DC Converters for Power Quality Improvement at Input AC Mains  

Microsoft Academic Search

This paper deals with the analysis, design and DSP based hardware implementation of four different topologies of high frequency isolated AC-DC converters in discontinuous current mode (DCM) of operation used for power quality improvement at input AC mains. The design equations, modeling, simulated and experimental results of these AC-DC converters are presented for their performance evaluation. Modeling and simulation is

B. P. Singh; S. Dwivedi

2006-01-01

64

UPS with input commutation between ac and dc sources of power  

SciTech Connect

An uninterruptible power supply is described, said power supply comprising: AC input terminal means for receiving a first AC voltage from an AC power source; DC input terminal means for receiving a first DC voltage from a DC power source; AC output terminal means for connecting to a load; converter means for converting said first AC voltage to a second DC voltage across electrical charge storage means coupled to said converter means, said second DC voltage being larger than the maximum peak voltage of said first AC voltage and said first DC voltage; switching means coupled to said AC power source and said DC power source for selectively connecting said AC power source or said DC power source to said converter means; inverter means coupled to said electrical charge storage means for receiving said second DC voltage and inverting said second DC voltage to a second AC voltage, said second AC voltage being coupled to said AC output terminal means; and control means coupled to said switching means for controlling the operation of said switching means, said control means operating said switching means to connect said AC power source to said converter means only when said first AC voltage is within a predetermined range and operating to connect said DC power source to said converter means when said first AC voltage is outside of said range.

Severinsky, A.J.

1993-08-31

65

Interconnection of distributed power to the distribution network  

Microsoft Academic Search

The interconnection of distributed power resources, normally through a power electronic converter, to the distribution network brings challenges of its own. Due to the distributed nature of these resources, they are implemented in large numbers onto the same, sometimes remote, distribution network. These challenges include power quality issues, network stability, power balancing considerations, voltage regulation, protection protocols and unwanted islanding

Johan H. R. Enslin

2004-01-01

66

Forty-eighth annual power distribution conference  

SciTech Connect

This book contains papers presented at the Forty-eighth Annual Power Distribution Conference held in 1995 at Austin, Texas. The topics of the papers include power quality in power distribution systems, methods to improve power quality, power system communications, automation of distribution systems, distributed data acquisition, energy efficiency in industrial plants, weather data in operation of distribution systems, detection and location of failed or failing equipment in power distribution systems, lightning and overvoltage protection, distribution cable research update, and equipment protection devices for residential power distribution systems.

NONE

1995-12-31

67

Ac/dc/ac high voltage traction drives with quasi-zero reactive power demand  

SciTech Connect

The new GTO devices allow the design of forced-commuted high power converters (up to several MVA`s). However, they cannot operate at high switching frequency, thus producing waveforms affected by remarkable harmonic distortion, especially if conventional converter topologies are used. A novel ac/dc/ac conversion structure has been developed referring to single-phase ac (25 kV/50 Hz) traction systems; high voltage converters delivering multilevel voltage waveforms with lower harmonic content have been employed on both the line-side and the motor-side. High performance techniques have been studied to control the whole system, assuring a quasi-unitary power factor and a low distorted line current. Simulation results confirm the validity of the methodologies proposed and of the analyses performed.

Bertini, S.; Ghiara, T.; Marchesoni, M. [Univ. of Genova (Italy). Dept. of Electrical Engineering] [Univ. of Genova (Italy). Dept. of Electrical Engineering

1993-10-01

68

Building Block Converter Module for Universal (AC-DC, DC-AC, DC-DC) Fully Modular Power Conversion Architecture  

Microsoft Academic Search

This paper presents the configuration and control methods for a building block module suitable for application in a fully modular, AC-DC, DC-AC and DC-DC power conversion architecture, where the modules can be connected in any combination of series and parallel connections and support bidirectional power flow. The advantages of the proposed configuration, which is a combination of AC PWM full

Harish K. Krishnamurthy; Raja Ayyanar

2007-01-01

69

ac Magnetization transport and power absorption in nonitinerant spin chains.  

PubMed

We investigate the ac transport of magnetization in nonitinerant quantum systems such as spin chains described by the XXZ Hamiltonian. Using linear response theory, we calculate the ac magnetization current and the power absorption of such magnetic systems. Remarkably, the difference in the exchange interaction of the spin chain itself and the bulk magnets (i.e., the magnetization reservoirs), to which the spin chain is coupled, strongly influences the absorbed power of the system. This feature can be used in future spintronic devices to control power dissipation. Our analysis allows us to make quantitative predictions about the power absorption, and we show that magnetic systems are superior to their electronic counterparts. PMID:18764149

Trauzettel, Björn; Simon, Pascal; Loss, Daniel

2008-07-01

70

Protection scheme for a new AC railway traction power system  

Microsoft Academic Search

The new, 160 mile long Amtrak Northeast Corridor railway electrification project has four supply substations that connect 115 kV utility power to the 55 kV single-phase, AC traction power system. Eighteen autotransformer-paralleling stations are spaced along the route. Each autotransformer connects the overhead catenary to an auxiliary feeder line, with the rails tied to an intermediate point of the autotransformer.

T. Sezi; F. E. Menter

1999-01-01

71

Influence of Critical Current Density Distribution on Transport AC Losses for Round Superconducting Wire  

NASA Astrophysics Data System (ADS)

The AC loss per cycle per unit length of a round superconducting wire has been theoretically analyzed based on the critical state model and numerically calculated from the power-law model. By using Bean's critical state model, it is found that the distribution of critical current density J c which increases from the center to the edge along a radial direction lowers the loss value. And the sharper the J c varies, the more significant the loss reduction. After considering the coupling of thermoelectric interaction, the results show that the temperature in superconducting wires gradually increases and finally becomes stable. The temperature of stable state has a dependence on the J c distribution and the rise of temperature has an important effect on the AC loss behavior.

Huang, Chen-Guang; Yong, Hua-Dong; Zhou, You-He

2013-07-01

72

Space station automation of common module power management and distribution  

NASA Technical Reports Server (NTRS)

The purpose is to automate a breadboard level Power Management and Distribution (PMAD) system which possesses many functional characteristics of a specified Space Station power system. The automation system was built upon 20 kHz ac source with redundancy of the power buses. There are two power distribution control units which furnish power to six load centers which in turn enable load circuits based upon a system generated schedule. The progress in building this specified autonomous system is described. Automation of Space Station Module PMAD was accomplished by segmenting the complete task in the following four independent tasks: (1) develop a detailed approach for PMAD automation; (2) define the software and hardware elements of automation; (3) develop the automation system for the PMAD breadboard; and (4) select an appropriate host processing environment.

Miller, W.; Jones, E.; Ashworth, B.; Riedesel, J.; Myers, C.; Freeman, K.; Steele, D.; Palmer, R.; Walsh, R.; Gohring, J.

1989-01-01

73

Universal instantaneous power theory for DC, single-phase AC sinusoidal and nonsinusoidal circuits  

Microsoft Academic Search

A novel power component theory based on instantaneous power concept for single-phase AC circuits is proposed in this paper. Every kind of power component advanced here is concerned directly with the instantaneous power process in circuits and possesses clear physical meaning. This new power component definition theory is immediately suited to DC, single-phase AC sinusoidal and nonsinusoidal circuits at the

Dairun Zhang; Nianci Huang

2000-01-01

74

Development of an analytical tool to study power quality of AC power systems for large spacecraft  

NASA Technical Reports Server (NTRS)

A harmonic power flow program applicable to space power systems with sources of harmonic distortion is described. The algorithm is a modification of the Electric Power Research Institute's HARMFLO program which assumes a three phase, balanced, AC system with loads of harmonic distortion. The modified power flow program can be used with single phase, AC systems. Early results indicate that the required modifications and the models developed are quite adequate for the analysis of a 20 kHz testbed built by General Dynamics Corporation. This is demonstrated by the acceptable correlation of present results with published data. Although the results are not exact, the discrepancies are relatively small.

Kraft, L. Alan; Kankam, M. David

1991-01-01

75

Development of an analytical tool to study power quality of ac power systems for large spacecraft  

NASA Technical Reports Server (NTRS)

A harmonic power flow program applicable to space power systems with sources of harmonic distortion is described. The algorithm is a modification of Electric Power Research Institute's HARMFLO program which assumes a three-phase, balanced, ac system with loads of harmonic distortion. The modified power flow program can be used with single phase, ac systems. Early results indicate that the required modifications and the models developed are quite adequate for the analysis of a 20-kHz testbed built by General Dynamics Corporation. This is demonstrated by the acceptable correlation of the present results with published data. Although the results are not exact, the discrepancies are relatively small.

Kraft, L. A.; Kankam, M. D.

1991-01-01

76

Input\\/output harmonic free current link three-phase AC power supply  

Microsoft Academic Search

The three-phase current link AC to AC power supply, a relatively new topology for AC power supply application, has several potential advantages such as smaller number of magnetic components, lower switching frequency and more rugged operation. Despite this, it has received very little attention by the researchers, and the majority of work found in the literature is confined to the

Hamid Reza Karshenas

1997-01-01

77

Improved transistorized AC motor controller for battery powered urban electric passenger vehicles  

Microsoft Academic Search

An ac motor controller for an induction motor electric vehicle drive system was designed, fabricated, tested, evaluated, and cost analyzed. A vehicle performance analysis was done to establish the vehicle tractive effort-speed requirements. These requirements were then converted into a set of ac motor and ac controller requirements. The power inverter is a three-phase bridge using power Darlington transistors. The

S. C. Peak

1982-01-01

78

AC three-phase power transmission system for Amtrak's new locomotives F69PH-AC  

Microsoft Academic Search

Advances in the field of three-phase drives for rail vehicles are described with reference to the power transmission system for the high-speed four-axle F69PC-AC locomotive. This model of locomotive incorporates state-of-the-art three-phase technology in the traction and head-end power systems. Traction converters, which are of the voltage-source inverter type with gate-turn-off thyristors, supply power to the squirrel-cage three-phase induction motors

J. W. Fischer

1989-01-01

79

Description of a 20 kilohertz power distribution system  

NASA Astrophysics Data System (ADS)

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 links multiphase 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.

Hansen, I. G.

80

Improved Transistorized AC Motor Controller for Battery Powered Urban Electric Passenger Vehicles.  

National Technical Information Service (NTIS)

The objectives of this program for an improved ac motor controller for battery powered urban electric passenger vehicles were: the design, fabrication, test, evaluation and cost analysis of an engineering model controller for an ac induction motor drive s...

S. C. Peak

1982-01-01

81

Voltage control availability of distributed generators in power distribution system  

Microsoft Academic Search

In spite of many profitable or advantageous natures of distributed generators (DGs), for power systems, such badly behaved natures of DGs as (1) unstable power output, (2) voltage problem, (3)harmonics, (4)reverse power flow, etc. also exist. Therefore, it has been always emphasized that the unfavorable effects should not exist when distributed generators are connected to the power system. However, in

K. Nara; S. Ishizu; Y. Mishima

2005-01-01

82

Power-law stellar distributions  

NASA Astrophysics Data System (ADS)

The density profiles and other quantities of physical interest for spherically symmetric systems are computed by assuming that a collisionless stellar gas may relax to the non-Gaussian power-law distribution suggested by the nonextensive kinetic theory. There are two different classes of solutions. The first class behaves like a subset of the polytropic Lane Emden spheres, whereas the second one corresponds to a transition between two different potytropic indices. Unlike the isothermal Maxwellian sphere, the total mass and sizes of both classes are finite for a large range of the nonextensive q-parameter.

Lima, J. A. S.; de Souza, R. E.

2005-05-01

83

Space station power management and distribution  

NASA Technical Reports Server (NTRS)

The power system architecture is presented by a series of schematics which illustrate the power management and distribution (PMAD) system at the component level, including converters, controllers, switchgear, rotary power transfer devices, power and data cables, remote power controllers, and load converters. Power distribution options, reference power management, and control strategy are also outlined. A summary of advanced development status and plans and an overview of system test plans are presented.

Teren, F.

1985-01-01

84

A harmonic-free AC to AC power supply using DC current link: steady-state analysis and design  

Microsoft Academic Search

This paper is concerned with the steady-state analysis and design of an sinusoidal input\\/output AC to AC power supply with DC current link. Despite many advantages of such a structure, its application in fixed frequency power supplies has received very little attention in the literature. Steady-state modeling of the system is carried out. Unity power factor operation of the system

Hamid R Karshenas; S. B. Dewan

1998-01-01

85

Transient stability analysis of ac-dc power systems  

NASA Astrophysics Data System (ADS)

A non-linear model of a combined high-voltage ac-dc power system was digitally simulated. The model is used for the study and prediction of the effects of transient interactions between a high-voltage-direct-current (HVDC) transmission line and turbine-generator-shaft torsional behavior when the system is subjected to large disturbances. Improvement of a-c line loadability due to the stabilizing influence of a HVDC link was also examined. Turbine-generator torsional interaction studies were based on subsynchronous phenomena requiring an evaluation of the frequency, magnitude and decay of the subsynchronous currents in the ac-dc system following major system disturbances. The complex waveform of subsynchronous current, obtained by digital simulation, was analyzed using the Fast FOURIER Transform technique. Results demonstrate that a HVDC link can affect the incidence of turbine-generator torsionals, can significantly improve the stability of the system in general and can be used to effect increased loadability of the a-c lines.

Teshome, A.

1980-12-01

86

Power Electronic Transformer based Three-Phase PWM AC Drives  

NASA Astrophysics Data System (ADS)

A Transformer is used to provide galvanic isolation and to connect systems at different voltage levels. It is one of the largest and most expensive component in most of the high voltage and high power systems. Its size is inversely proportional to the operating frequency. The central idea behind a power electronic transformer (PET) also known as solid state transformer is to reduce the size of the transformer by increasing the frequency. Power electronic converters are used to change the frequency of operation. Steady reduction in the cost of the semiconductor switches and the advent of advanced magnetic materials with very low loss density and high saturation flux density implies economic viability and feasibility of a design with high power density. Application of PET is in generation of power from renewable energy sources, especially wind and solar. Other important application include grid tied inverters, UPS e.t.c. In this thesis non-resonant, single stage, bi-directional PET is considered. The main objective of this converter is to generate adjustable speed and magnitude pulse width modulated (PWM) ac waveforms from an ac or dc grid with a high frequency ac link. The windings of a high frequency transformer contains leakage inductance. Any switching transition of the power electronic converter connecting the inductive load and the transformer requires commutation of leakage energy. Commutation by passive means results in power loss, decrease in the frequency of operation, distortion in the output voltage waveform, reduction in reliability and power density. In this work a source based partially loss-less commutation of leakage energy has been proposed. This technique also results in partial soft-switching. A series of converters with novel PWM strategies have been proposed to minimize the frequency of leakage inductance commutation. These PETs achieve most of the important features of modern PWM ac drives including 1) Input power factor correction, 2) Common-mode voltage suppression at the load end, 3) High quality output voltage waveform (comparable to conventional space vector PWM modulated two level inverter) and 4) Minimization of output voltage loss, common-mode voltage switching and distortion of the load current waveform due to leakage inductance commutation. All of the proposed topologies along with the proposed control schemes have been analyzed and simulated in MATLABSimulink. A hardware prototype has been fabricated and tested. The simulation and experimental results verify the operation and advantages of the proposed topologies and their control.

Basu, Kaushik

87

QPSK modulation for AC-power-signal-biased visible light communication system  

NASA Astrophysics Data System (ADS)

With the integration of light emitting diode (LED), visible light communication (VLC) can provide wireless communication link using the lightning system. Due to the consideration of power efficiency, AC-LED has the design of reducing energy waste with alternating current from the power outlet. In this work, we propose an AC-power-signalbiased system that provides communication on both DC-LED and AC-LED. The bias circuit is designed to combine ACpower signal and the message signal with QPSK format. This driving scheme needs no AC-to-DC converters and it is suitable for driving AC LED. Synchronization is completed to avoid threshold effect of LED.

Liu, Yu-Feng; Yeh, Chien-Hung; Chow, Chi-Wai; Liu, Yang

2013-01-01

88

Distribution of Unlinked Receptor Sites for Transposed Ac Elements from the Bz-M2(ac) Allele in Maize  

PubMed Central

We have shown before that the Ac element from the maize bz-m2(Ac) allele, located in the short arm of chromosome 9 (9S), transposes preferentially to sites that are linked to the bz donor locus. Yet, about half of the Ac transpositions recovered from bz-m2(Ac) are in receptor sites not linked to the donor locus. In this study, we have analyzed the distribution of those unlinked receptor sites. Thirty-seven transposed Ac (trAc) elements that recombined independently of the bz locus were mapped using a set of wx reciprocal translocations. We found that the distribution of unlinked receptor sites for trAs was not random. Ten trAcs mapped to 9L, i.e., Ac had transposed to sites physically, if not genetically, linked to the donor site. Among chromosomes other than 9, the Ac element of bz-m2(Ac) appeared to have transposed preferentially to certain chromosomes, such as 5 and 7, but infrequently to others, such as 1, the longest chromosome in the maize genome. The seven trAc elements in chromosome 5 were mapped relative to markers in 5S and 5L and localized to both arms of 5. We also investigated the transposition of Ac to the homolog of the donor chromosome. We found that Ac rarely transposes from bz-m2(Ac) to the homologous chromosome 9. The clustering of Ac receptor sites around the donor locus has been taken to mean that a physical association between the donor site and nearby receptor sites occurs during transposition. The preferential occurrence of 9L among chromosomes harboring unlinked receptor sites would be expected according to this model, since sites in 9L would tend to be physically closer to 9S than sites in other chromosomes. The nonrandom pattern seen among the remaining chromosomes could reflect an underlying nuclear architecture, i.e., an ordering of the chromosomes in the interphase nucleus, as suggested from previous cytological observations.

Dooner, H. K.; Belachew, A.; Burgess, D.; Harding, S.; Ralston, M.; Ralston, E.

1994-01-01

89

Control and stability of power inverters feeding renewable power to weak AC grids with no or low mechanical inertia  

Microsoft Academic Search

The number of power inverter installations feeding renewable energy to AC grids is worldwide increasing. The type of inverter used depends on the power level and on the AC system conditions at the terminal connection point. Line-commutated inverters need sufficient short circuit power. Self-commutated inverters can even operate without an existing grid. In both the cases the mechanical inertia decreases

W. Kuehn

2009-01-01

90

Transient stability enhancement in power system with distributed static series compensator (DSSC)  

Microsoft Academic Search

Long distance AC transmission system is often subjected to stability problems which limit the transmission capability. Large power systems often suffer from weakly damped swings between synchronous generators. This paper aims to enhance the transient stability of the power system with the use of distributed static series compensator (DSSC). First of all, a detailed simulation model of the DSSC has

S. Golshannavaz; M. Mokhtari; M. Khalilian; D. Nazarpour

2011-01-01

91

Optimal operation of distribution power system including distributed generator  

Microsoft Academic Search

A new model for distribution system reconfiguration (DSR) integrated with optimal power flow (OPF) and optimal capacitor switching (OCS) based on a hybrid approach is proposed in this paper. The objective is to minimize the generation cost of the whole distribution power system, and is subject to constraints such as capacity limit of branches, minimum and maximum power limits of

J. Shu; S. S. Quan; L. Z. Zhang

2010-01-01

92

An AC Drive System with Flexible Driving Modes Applied in Ship Power Station  

Microsoft Academic Search

This paper designed a special ac drive system which could realize directly or softly starting up ac motors. This ac drive system is consisted with boost converter and 3-phase inverter, it could operate either from rectifier utility power or battery packs. The duty cycle forward control is adopted in boost control loop to assure the stability of the output dc

Chao Zeyun; Zheng Zhong

2010-01-01

93

Point of collapse methods applied to AC\\/DC power systems  

Microsoft Academic Search

The authors describe an extension of the point of collapse method developed for studies of AC systems to the determination of saddle-node bifurcations in power systems including high voltage direct current (HVDC) transmission. Bus voltage profiles are illustrated for an AC\\/DC test system. They significantly differ from the profiles of pure AC systems for typical system models. In particular, voltage

C. A. Canizares; Fernando L. Alvarado; Christopher L. DeMarco; Ian Dobson; Willis F. Long

1992-01-01

94

Power factor improvement of an AC\\/AC converter by association of PDM control and passive filtering  

Microsoft Academic Search

PDM control and passive filtering are combined to improve, to a significant degree and at lower costs, the power factor of an AC\\/AC power converter consisting of a single-phase diode bridge rectifier and a series inverter without the smoothing filter of the DC voltage. A low-pass filter absorbs the harmonics of the rectifier input current, whereas PDM control, applied to

Abdelhalim Sandali; Pierre Sicard; Ahmed Cheriti

2002-01-01

95

Direct power and torque control for three-level NPC based PWM ac\\/dc\\/ac converter  

Microsoft Academic Search

This paper presents a new control scheme for three-level neutral point clamped (NPC) based PWM AC\\/DC\\/AC converter. The direct power control (DPC) for front-end three-level PWM rectifier and direct torque control (DTC) for back-end three-level PWM inverter-fed induction motor are adopted respectively. A power feed-forward control loop from inverter to rectifier side is introduced to obtain better dynamic performance for

Zhang Yingchao; Zhao Zhengming; Lu Ting; Li Long

2009-01-01

96

Electric power distribution and load transfer system  

SciTech Connect

This patent describes a power distribution system. It comprises at least two switch means for controlling the application of power from a power source to a power output; at least two current means for preventing reverse power flow through respective ones of switch means; and processing means for providing control signals to operate the switch means, effective to switch respective ones of the power sources between on and off states with respect to the power output.

Bradford, M.P.; Parkinson, G.W.; Grant, R.M.

1989-10-10

97

Power Converters for Feeding Asynchronous Traction Motors of Single-Phase AC Vehicles  

Microsoft Academic Search

Asynchronous induction motors are very well suited to powerful traction drives. For electric locomotives and motor coaches with single-phase supply, a power conversion on the vehicle is necessary. Three different types of static power converters for this application are described. Indirect ac converters with direct voltage link have been developed successfully in the past. For indirect ac converters with direct

Wolfgang Lienau; Adolf Muller-Hellmann; Hans-Christoph Skudelny

1980-01-01

98

Improved power quality AC-DC converter for electric multiple units in electric traction  

Microsoft Academic Search

This paper presents the performance analysis of an improved power quality AC-DC converter (IPQC) fed vector controlled induction motor drive (VCIMD) for electric multiple units (EMU) application in electric traction of Indian railways. The IPQC enhances the input power factor close to unity and also reduces the total harmonic distortion (THD) of AC mains current. The converter provides bi-directional power

Bhim Singh; G. Bhuvaneswari; Vipin Garg

2006-01-01

99

Hybrid power system intelligent operation and protection involving distributed architectures and pulsed loads  

NASA Astrophysics Data System (ADS)

Efficient and reliable techniques for power delivery and utilization are needed to account for the increased penetration of renewable energy sources in electric power systems. Such methods are also required for current and future demands of plug-in electric vehicles and high-power electronic loads. Distributed control and optimal power network architectures will lead to viable solutions to the energy management issue with high level of reliability and security. This dissertation is aimed at developing and verifying new techniques for distributed control by deploying DC microgrids, involving distributed renewable generation and energy storage, through the operating AC power system. To achieve the findings of this dissertation, an energy system architecture was developed involving AC and DC networks, both with distributed generations and demands. The various components of the DC microgrid were designed and built including DC-DC converters, voltage source inverters (VSI) and AC-DC rectifiers featuring novel designs developed by the candidate. New control techniques were developed and implemented to maximize the operating range of the power conditioning units used for integrating renewable energy into the DC bus. The control and operation of the DC microgrids in the hybrid AC/DC system involve intelligent energy management. Real-time energy management algorithms were developed and experimentally verified. These algorithms are based on intelligent decision-making elements along with an optimization process. This was aimed at enhancing the overall performance of the power system and mitigating the effect of heavy non-linear loads with variable intensity and duration. The developed algorithms were also used for managing the charging/discharging process of plug-in electric vehicle emulators. The protection of the proposed hybrid AC/DC power system was studied. Fault analysis and protection scheme and coordination, in addition to ideas on how to retrofit currently available protection concepts and devices for AC systems in a DC network, were presented. A study was also conducted on the effect of changing the distribution architecture and distributing the storage assets on the various zones of the network on the system's dynamic security and stability. A practical shipboard power system was studied as an example of a hybrid AC/DC power system involving pulsed loads. Generally, the proposed hybrid AC/DC power system, besides most of the ideas, controls and algorithms presented in this dissertation, were experimentally verified at the Smart Grid Testbed, Energy Systems Research Laboratory. All the developments in this dissertation were experimentally verified at the Smart Grid Testbed.

Mohamed, Ahmed

100

Minimum Loss Configuration of Power Distribution System  

Microsoft Academic Search

This paper presents a new method for minimum loss reconfiguration for radial power distribution system, in which the choice of the switches to be opened \\/ closed is based on the calculation of voltage at the buses, real and reactive power flowing through lines, real power losses and voltage deviation, using distribution load flow (DLF) program. In the process of

Jaswanti; T. Thakur

2006-01-01

101

Field and current distributions and ac losses in superconducting strips  

SciTech Connect

In this paper I discuss analytic and numerical calculations of the magnetic-field and sheet-current distributions in superconducting strips of width 2a and arbitrary thickness 2b at the center when the cross-section is an ellipse, a rectangle, and a shape intermediate between these limits. Using critical-state theory, I use several methods to determine the functional dependence of the ac transport-current losses upon F=I/I{sub c}, where I is the peak alternating current and I{sub c} is the critical current, and I discuss how this dependence can be affected by the cross-sectional shape, aspect ratio, and a flux-density-dependent critical current density J{sub c}(B).

Clem, John R.

2009-11-30

102

Optimal reactive power flow with distributed generating plants in electric power distribution systems  

Microsoft Academic Search

This paper presents the solution of reactive power flow optimization for electric power distribution systems integrating with distributed generating (Distributed Generator: DG) plants which can support daily load demand. To reduce the total energy losses of the entire system, transformer tap and reactive power injection from available reactive power source are required. The setting of variables based on a particular

U. Leeton; T. Ratniyomchai; T. Kulworawanichpong

2010-01-01

103

High frequency alternating current power distribution  

Microsoft Academic Search

The paper introduces high frequency alternating current (HFAC) power distribution as a new option in powering the equipment in telecommunications applications. A detailed comparison with powering schemes presently used in the telecommunication industry is part of the paper. The comparison is oriented towards the parameters of regulation, efficiency, input voltage range, output\\/input ripple, power density and EMI

J. Drobnik

1994-01-01

104

Comparison of Power Quality Improvement techniques in AC-DC Cuk Converter  

Microsoft Academic Search

The Improved Power Quality AC-DC Converters (IPQCs) provides enhanced power quality in terms of improved power factor and reduced Total Harmonic Distortion (THD) at the utility interface. This paper addresses comparison of power factor correction techniques for high frequency isolation based single phase Buck-Boost AC-DC Cuk Converter, which consists of only one switch resulting in reduced THD and improved power

J. Gnanavadivel; Vidhya Chellappa; N. Senthil Kumar

2011-01-01

105

Dynamic stability analysis of PV-injected power into a parallel AC-DC power system  

Microsoft Academic Search

The paper introduces an approach to solve the problem of damping the electromechanical oscillations of conventional plant-photovoltaic generator hybrid system. The photovoltaic generator is coupled directly to the DC-link of AC-DC parallel connection to a large power system. The intermittent nature of the photovoltaic generator imposes an unpredictable characterization of negative load which affects the power system dynamic stability. The

F. M. A. Ghali; H. A. El-Khashab; M. S. Abdel-Motaleb

1994-01-01

106

Single-phase ac losses in prototype HTS conductors for superconducting power transmission lines  

SciTech Connect

The authors report single-phase ac loss measurements on 8, 4, and 3-layer, multi-strand, HTS prototype conductors for power transmission lines. They use both calorimetric and electrical techniques. The agreement between the two techniques suggests that the interlayer current distribution in one-meter long conductors are representative of those in long conductors. The losses for the 8 and 4-layer conductors are in rough agreement, with the 8-layer losses being somewhat lower. The 3-layer conductor losses are substantially higher--probably due to unbalanced azimuthal currents for this configuration.

Daney, D.E.; Maley, M.P.; Boenig, H.J.; Willis, J.O.; Coulter, J.Y. [Los Alamos National Lab., NM (United States); Gherardi, L.; Coletta, G. [Pirelli Cavi SpA (Italy)

1998-12-01

107

Single-phase AC losses in prototype HTS conductors for superconducting power transmission lines  

NASA Astrophysics Data System (ADS)

We report single-phase AC loss measurements on 8-, 4-, and 3-layer, multi-strand, HTS prototype conductors for power transmission lines. We use both calorimetric and electrical techniques. The agreement between the two techniques suggests that the interlayer current distribution in 1-m long conductors are representative of those in long conductors. The losses for the 8- and 4-layer conductors are in rough agreement, with the 8-layer losses being somewhat lower. The 3-layer conductor losses are substantially higher - probably due to unbalanced azimuthal currents for this configuration.

Daney, D. E.; Maley, M. P.; Boenig, H. J.; Willis, J. O.; Coulter, J. Y.; Gherardi, L.; Coletta, G.

1998-12-01

108

D0 Cryogenic Controls I/O Base Power Distribution  

SciTech Connect

The D0 cryogenic control system has 3 I/O bases and 1 25 amp 24vdc power supply. Each I/O base uses both 120 vac and 24 vdc. There are as many as 14 modules in each base, depending on what type of module it may require ac or dc. Then there are as many as 32 devices (instrumentation) per module. There is a power distribution network that provides power to this system. It was configured so that no conductors, devices, or components could carry or receive more current or voltage than they could safely handle. This is done to protect both personel and components from fire, heat, and electric shock.

Markley, D.; /Fermilab

1991-03-09

109

Study on speeding performance of power propulsion system with the integration of AC and DC  

Microsoft Academic Search

In order to reduce the weight and size of vessel integrated power system (VIPS), the AC-DC integrated propulsion system was studied. The system mainly consists of double winding synchronous generators (DWSG) and the DC propelling motor. DWSG supplies both AC and DC power simultaneously. The mathematic models of the main components were presented. Expressions for DWSG and the computation method

Guan Tao; Fu Li-jun; Ji Feng; Xie Zhen

2009-01-01

110

Compensating procedures for power quality amplification of AC electrified railway systems using FACTS  

Microsoft Academic Search

The low power factor and the voltage fluctuation are two stability problems in many ac electrified railway systems. This paper surveys the usage of several types of Flexible AC Transmission Systems (FACTS) for power quality improvements of an electrified railway system which has been consisted of phase- controlled thyristor converters to feed the DC motor drives of their locomotives. The

Mohammad Ali Akbari Baseri; Mehdi Niaki Nezhad; Mohammad Ali Sandidzadeh

2011-01-01

111

High Frequency Power Distribution System.  

National Technical Information Service (NTIS)

The objective of this project was to provide the technology of high frequency, high power transmission lines to the 100 kW power range at 20 kHz frequency. In addition to the necessary design studies, a 150 m long, 600 V, 60 A transmission line was built,...

M. R. Patel

1986-01-01

112

Autonomous power management and distribution  

NASA Technical Reports Server (NTRS)

The goal of the Autonomous Power System program is to develop and apply intelligent problem solving and control to the Space Station Freedom's electric power testbed being developed at NASA's Lewis Research Center. Objectives are to establish artificial intelligence technology paths, craft knowledge-based tools and products for power systems, and integrate knowledge-based and conventional controllers. This program represents a joint effort between the Space Station and Office of Aeronautics and Space Technology to develop and demonstrate space electric power automation technology capable of: (1) detection and classification of system operating status, (2) diagnosis of failure causes, and (3) cooperative problem solving for power scheduling and failure recovery. Program details, status, and plans will be presented.

Dolce, Jim; Kish, Jim

1990-01-01

113

Improving the power quality performance for distributed power generation  

Microsoft Academic Search

The main aim of this paper is to analysis and improve the power quality (voltage sag, swell and harmonics) performance of smart grid connected inverter used in distributed generation. The structure of the designed controller consists of outer power with harmonic control loop, middle voltage control loop and inner current control loop for real and reactive power control in dq

R. Muralekrishnen; P. Sivakumar

2012-01-01

114

Control of Distributed Uninterruptible Power Supply Systems  

Microsoft Academic Search

In the last years, the use of distributed uninterruptible power supply (UPS) systems has been growing into the market, becoming an alternative to large conventional UPS systems. In addition, with the increasing interest in renewable energy integration and distributed generation, distributed UPS systems can be a suitable solution for storage energy in micro grids. This paper depicts the most important

Josep M. Guerrero; Lijun Hang; Javier Uceda

2008-01-01

115

Parallelising calculations in electric power distribution networks  

Microsoft Academic Search

CART (Computer Aided Reticulation of Townships) is a software package used for the design of radial, electrical power distribution networks. Having many transformers and large numbers of consumers in the distribution network significantly increases computation time. A distributed, service-based platform is being developed, with parallelisation functionality for CART as the flagship service. The system will be used to parallelise CART's

Y. Neumann; B. Dwolatzky

2002-01-01

116

A Simple Three-Phase Model for Distributed Static Series Compensator (DSSC) in Newton Power Flow  

Microsoft Academic Search

Load flow problems have always been an important issue in power system analysis and require proper modeling of system components. In this regard flexible AC transmission system (FACTS) controllers are modern devices that their modeling specially the series type is a challenging topic. This paper describes a three-phase model for distributed static series compensator (DSSC) based on extending the static

Reza Jalayer; Hossein Mokhtari

2009-01-01

117

SIMULTANEOUS CONTROL OF VOLTAGE AND POWER OF MICRO-TURBINE IN DISTRIBUTION NETWORK  

Microsoft Academic Search

Distributed Generation (DG) is expected to play an increasingly significant role in power generation in coming years. In Iran, more attention is recently paid to the Micro- Turbines (MTs), since 20% of the world's gas resources are believed to exist in Iran. A MT unit consists of a gas turbine engine, a permanent magnet generator, a 3-phase AC\\/DC rectifier and

B. Yousefpour; G. Gharehpetian; R. Noroozian; M. Nafar

118

Electric power distribution and load transfer system  

NASA Technical Reports Server (NTRS)

A power distribution system includes a plurality of power sources and load transfer units including transistors and diodes connected in series and leading to a common power output, each of the transistors being controller switchable subject to voltage levels of the respective input and output sides of said transistors, and the voltage and current level of said common power output. The system is part of an interconnection scheme in which all but one of the power sources is connected to a single load transfer unit, enabling the survival of at least a single power source with the failure of one of the load transfer units.

Bradford, Michael P. (Inventor); Parkinson, Gerald W. (Inventor); Grant, Ross M. (Inventor)

1987-01-01

119

Electric power distribution and load transfer system  

NASA Technical Reports Server (NTRS)

A power distribution system includes a plurality of power sources and load transfer units including transistors and diodes connected in series and leading to a common power output, each of the transistors being controller switchable subject to voltage levels of the respective input and output sides of said transistors, and the voltage and current level of said common power output. The system is part of an interconnection scheme in which all but one of the power sources is connected to a single load transfer unit, enabling the survival of at least a single power source with the failure of one of the load transfer units.

Bradford, Michael P. (Inventor); Parkinson, Gerald W. (Inventor); Grant, Ross M. (Inventor)

1989-01-01

120

Ground Fault and Overcurrent Protection Criteria for Coal Mine AC Distribution Systems.  

National Technical Information Service (NTIS)

Ground fault and overcurrent protection criteria for coal mine ac distribution systems were examined by authorization of the Bureau of Mines. The report begins with a literature review that discusses relaying topics including instrument transformers, grou...

J. A. Kiefer J. L. Kohler

1980-01-01

121

Power operator, effective Hamiltonian and AC Poynting splitting  

Microsoft Academic Search

The concept of the effective Hamiltonian is introduced and the first- and second-order perturbative solutions are obtained for a nondegenerate system. By solving the first-order effective Schrodinger equation, the author derives the AC Poynting splitting for the exact field. In the long wavelength approximation, the AC Poynting splitting is shown to reduce to the AC Stark splitting if the electric

Kuo-ho Yang

1983-01-01

122

Wind power distribution over the ocean  

NASA Astrophysics Data System (ADS)

Probability distribution and power density of wind speed over global oceans are computed from eight years of QuikSCAT measurements. They describe the variation and higher moments of wind speed that are critical in relating the non-linear effects of wind on electric power generation capability, shipping hazard, and air-sea exchanges in heat, water, and greenhouse gases. The power density distribution confirms our general knowledge of atmospheric circulation related to mid-latitude storm tracks, trade winds, and monsoons. It also reveals regions of high wind power associated with flow distortion by land, wind channeled by land topography, and buoyancy effect on turbulent stress driven by ocean fronts.

Liu, W. Timothy; Tang, Wenqing; Xie, Xiaosu

2008-07-01

123

Power Quality Improvements in Isolated Twelve-Pulse AC-DC Converters Using Delta\\/Double-Polygon Transformer  

Microsoft Academic Search

This paper presents twelve-pulse AC-DC converters for constant current applications. The delta\\/delta-star transformer based 12-pulse AC-DC converter doesn't meet power quality requirements. To overcome this drawback, a delta\\/double polygon transformer based AC-DC converter is designed, simulated and developed to compare its performance in terms of power quality parameters with that of delta\\/delta-star transformer based AC-DC converter. To meet power quality

Bhim Singh; Sanjay Gairola; Ambrish Chandra; Kamal Al-Haddad

2007-01-01

124

Preliminary study of AC power feeders for AGS booster  

SciTech Connect

It has been proposed that the AGS Heavy Ion/Proton Booster be excited directly from the electric power distribution system without intervening an energy storage buffer such as an MG set or a magnetic energy buffer. The average power requirement of the AGS Booster is less than many single-loads presently housed on the lab site. However, the power swing will be the largest single pulsating load on the lab site. The large power swings will impact on the power grid producing utility-line disturbances such as voltage fluctuations and harmonic generation. Thus, it is necessary to carefully evaluate the quality of the electric power system resulting from the interconnection, such that the utility system is not degraded either on the lab site or at LILCO's substation.

Meth, M.

1992-07-17

125

Preliminary study of AC power feeders for AGS booster  

SciTech Connect

It has been proposed that the AGS Heavy Ion/Proton Booster be excited directly from the electric power distribution system without intervening an energy storage buffer such as an MG set or a magnetic energy buffer. The average power requirement of the AGS Booster is less than many single-loads presently housed on the lab site. However, the power swing will be the largest single pulsating load on the lab site. The large power swings will impact on the power grid producing utility-line disturbances such as voltage fluctuations and harmonic generation. Thus, it is necessary to carefully evaluate the quality of the electric power system resulting from the interconnection, such that the utility system is not degraded either on the lab site or at LILCO`s substation.

Meth, M.

1992-07-17

126

High frequency power distribution system  

NASA Technical Reports Server (NTRS)

The objective of this project was to provide the technology of high frequency, high power transmission lines to the 100 kW power range at 20 kHz frequency. In addition to the necessary design studies, a 150 m long, 600 V, 60 A transmission line was built, tested and delivered for full vacuum tests. The configuration analysis on five alternative configurations resulted in the final selection of the three parallel Litz straps configuration, which gave a virtually concentric design in the electromagnetic sense. Low inductance, low EMI and flexibility in handling are the key features of this configuration. The final design was made after a parametric study to minimize the losses, weight and inductance. The construction of the cable was completed with no major difficulties. The R,L,C parameters measured on the cable agreed well with the calculated values. The corona tests on insulation samples showed a safety factor of 3.

Patel, Mikund R.

1986-01-01

127

Nearly Unity Power-Factor of the Modular Three-Phase AC to DC Converter with Minimized DC Bus Capacitor  

NASA Astrophysics Data System (ADS)

The analysis and design of nearly unity power-factor and fast dynamic response of the modular three-phase ac to dc converter using three single-phase isolated SEPIC rectifier modules with minimized dc bus capacitor is discussed, based on power balance control technique. The averaged small-signal technique is used to obtain the inductor current compensator, thus resulting in the output impedance and audio susceptibility become zero, that is, the output voltage of the converter presented in this paper is independent of the variations of the dc load current and the utility voltage. The proposed system significantly improves the dynamic response of the converter to load steps with minimized dc bus capacitor for Distributed Power System (DPS). A 600W prototype modular three-phase ac to dc converter comprising three 200W single-phase SEPIC rectifier modules with the proposed control scheme has been designed and implemented. The proposed system is confirmed by experimental implementation.

Chunkag, Viboon; Kamnarn, Uthen

128

Active Power and Nonactive Power Control of Distributed Energy Resources  

SciTech Connect

Distributed energy resources (DE) have been widely used in the power systems to supply active power, and most of the present DE resources are operated with limited or without nonactive power capability. This paper shows that with a slight modification in hardware configuration and a small boost in the power ratings, as well as proper implementation of control strategies, a DE system with a power electronics converter interface can provide active power and nonactive power simultaneously and independently. A DE can provide dynamic voltage regulation to the local bus because of its nonactive power capability. Furthermore, the proposed DE control method in this paper can effectively compensate the unbalance in the local voltage. The system requirements such as the inverter current rating and the dc voltage rating are discussed. The analysis of the system requirements to provide nonactive power shows that it is cost-effective to have DE provide voltage regulation.

Xu, Yan [ORNL; Li, Fangxing [ORNL; Rizy, D Tom [ORNL; Kueck, John D [ORNL

2008-01-01

129

DECOUPLED AC\\/DC LOAD FLOW FOR MONTE CARLO SIMULATION OF METRO POWER SYSTEM  

Microsoft Academic Search

Railway power system planners and operators need a tool for testing their designs or new timetables. This paper presents a tool for the DC traction systems, an algorithm called decoupled AC\\/DC load flow. The main feature of this algorithm is to separate the solution of AC and DC equations. Therefore, a minimum number of iterations is needed to avoid any

A. DER MINASSIANS; G. B. GHAREHPETIAN

130

AC losses of HTS power transmission cables using Bi2223 tapes with twisted filaments  

Microsoft Academic Search

TEPCO and Furukawa have been developing compact 66 kV HTS power cables that can fit into 150 mm ducts. To realize these compact and highly efficient cables, decreasing AC losses in the cables is important. An effective method for reducing the AC losses is to suppress the electromagnetic coupling between layers and between filaments: equalizing the impedance of each layer

S. Mukoyama; K. Miyoshi; H. Tsubouti; H. Tanaka; A. Takagi; K. Wada; S. Megro; K. Matsuo; S. Honjo; T. Mimura; Y. Takahashi

2001-01-01

131

Spacecraft solid state power distribution switch  

NASA Astrophysics Data System (ADS)

As a spacecraft performs its mission, various loads are connected to the spacecraft power bus in response to commands from an on board computer, a function called power distribution. For the Mariner Mark II set of planetary missions, the power bus is 30 volts dc and when loads are connected or disconnected, both the bus and power return side must be switched. In addition, the power distribution function must be immune to single point failures and, when power is first applied, all switches must be in a known state. Traditionally, these requirements have been met by electromechanical latching relays. This paper describes a solid state switch which not only satisfies the requirements but incorporates several additional features including soft turn on, programmable current trip point with noise immunity, instantaneous current limiting, and direct telemetry of load currents and switch status. A breadboard of the design has been constructed and some initial test results are included.

Praver, G. A.; Theisinger, P. C.

132

Distributed system for electrical power quality improvement  

Microsoft Academic Search

On the basis of the current trends for solving complex technical problems, a new concept of power quality improvement is proposed. It consists in creating a distributed system for supply conditions improvement in a given islanding power system, in e.g. geographical terms (with determined points of delivery), or as an internal installation system of an industrial consumer.

KLEMPKA Ryszard

2008-01-01

133

Distribution of injected power fluctuations in electroconvection  

Microsoft Academic Search

We report on the distribution spectra of the fluctations in the amount of power injected into a liquid crystal undergoing electroconvective flow. The probability distribution functions (PDFs) of the fluctuations as well as the magnitude of the fluctuations have been determined in a wide range of imposed stress both for `unconfined' and `confined' flow geometries. These spectra are compared to

Tibor Tóth-Katona; J. T. Gleeson

2004-01-01

134

Distribution of Injected Power Fluctuations in Electroconvection  

Microsoft Academic Search

We report on the distribution spectra of the fluctations in the amount of power injected into a liquid crystal undergoing electroconvective flow. The probability distribution functions (PDFs) of the fluc­tuations as well as the magnitude of the fluctuations have been determined in a wide range of imposed stress both for unconfined and confined flow geometries. These spectra are compared to

Tibor Tóth-Katona; J. T. Gleeson

2003-01-01

135

Space Solar Power Management and Distribution (PMAD)  

NASA Technical Reports Server (NTRS)

This paper presents, in viewgraph form, SSP PMAD (Space Solar Power Management and Distribution). The topics include: 1) Architecture; 2) Backside Thermal View; 3) Solar Array Interface; 4) Transformer design and risks; 5) Twelve phase rectifier; 6) Antenna (80V) Converters; 7) Distribution Cables; 8) Weight Analysis; and 9) PMAD Summary.

Lynch, Thomas H.

2000-01-01

136

Multiphase power flow and state estimation for power distribution systems  

SciTech Connect

A multiphase power flow model and state estimation for distribution systems are formulated and solution methods are presented. The multiphase power flow model is based on fully asymmetric modeling of the power distribution system. The state estimation uses this model in conjunction with synchronized measurements. The method provides an estimate of the total electric load for each distribution circuit without the requirement of knowledge of the individual loads along the circuit. The paper addresses the following issues: (a) modeling issue, (b) implementation issue, (c) observability issue and (d) performance issue. The overall performance of the method is described in terms of confidence level versus error. The concepts are illustrated with a simplified distribution system.

Meliopoulos, A.P.S. [Georgia Inst. of Tech., Atlanta, GA (United States). School of Electrical and Computer Engineering] [Georgia Inst. of Tech., Atlanta, GA (United States). School of Electrical and Computer Engineering; Zhang, F. [ABB Automated Distribution Div., Raleigh, NC (United States)] [ABB Automated Distribution Div., Raleigh, NC (United States)

1996-05-01

137

Transient current measurement of improved AC\\/DC current transformer for power system  

Microsoft Academic Search

The transient current measurement of the power system by an improved ac\\/dc current transformer is developed. The transient performance details and calculation formulas of the transformer are analyzed and derived. The important design bases for transient current measurement of the current transformer used to the power system are given. Testing results show that the transient error of 5000-A improved ac\\/dc

Shiyan Ren; Mingming Li; Xusheng Chen

1995-01-01

138

Vibration Monitoring of Power Distribution Poles  

SciTech Connect

Some of the most visible and least monitored elements of our national security infrastructure are the poles and towers used for the distribution of our nation’s electrical power. Issues surrounding these elements within the United States include safety such as unauthorized climbing and access, vandalism such as nut/bolt removal or destructive small arms fire, and major vandalism such as the downing of power poles and towers by the cutting of the poles with a chainsaw or torches. The Idaho National Laboratory (INL) has an ongoing research program working to develop inexpensive and sensitive sensor platforms for the monitoring and characterization of damage to the power distribution infrastructure. This presentation covers the results from the instrumentation of a variety of power poles and wires with geophone assemblies and the recording of vibration data when power poles were subjected to a variety of stimuli. Initial results indicate that, for the majority of attacks against power poles, the resulting signal can be seen not only on the targeted pole but on sensors several poles away in the distribution network and a distributed sensor system can be used to monitor remote and critical structures.

Clark Scott; Gail Heath; John Svoboda

2006-04-01

139

Control System Design and Simulation of an AC\\/DC - DC\\/DC - DC\\/AC Power Converter for a Permanent Magnet Wind Power Generator in Rural Power Generation  

Microsoft Academic Search

This paper deals with the voltage and frequency control of the generated electricity from a permanent magnet wind-turbine. The wind turbine is directly connected to a permanent magnet synchronous generator in order to avoid the losses associated to the gearbox so that only an AC\\/DC\\/AC power converter is used to control the variable voltage and frequency. The AC\\/DC converter is

Roberto Morales; Rafael Ordonez; Marco A. Morales; Vicente Flores

2009-01-01

140

Hardware Model of a Shipboard Zonal Electrical Distribution System (ZEDS): Alternating Current/Direct Current (AC/DC).  

National Technical Information Service (NTIS)

A hardware model of a shipboard electrical distribution system based on aspects of the DDG 51 Flight IIA, Arleigh Burke class, 60Hz Alternating Current (AC) and the future direct current (DC) zonal electrical distribution system (ZEDS). These distribution...

C. N. Tidd

2010-01-01

141

A small signal AC analysis program for spacecraft electrical power systems  

Microsoft Academic Search

A computer program has been developed which models the small signal performance of a space electrical power system. The Small Signal AC program computers bus impedances, transfer functions, and transient parameters of an arbitrary power system based on a library of generic power system component models. The program is interactive and requires minimal knowledge of circuit details so as to

J. E. Chen; K. K. Saylors

1985-01-01

142

Galileo spacecraft power management and distribution system  

NASA Technical Reports Server (NTRS)

The Galileo PMAD (power management and distribution system) is described, and the design drivers that established the final as-built hardware are discussed. The spacecraft is powered by two general-purpose heat-source-radioisotope thermoelectric generators. Power bus regulation is provided by a shunt regulator. Galileo PMAD distributes a 570-W beginning of mission (BOM) power source to a user complement of some 137 load elements. Extensive use of pyrotechnics requires two pyro switching subassemblies. They initiate 148 squibs which operate the 47 pyro devices on the spacecraft. Detection and correction of faults in the Galileo PMAD is an autonomous feature dictated by requirements for long life and reliability in the absence of ground-based support. Volatile computer memories in the spacecraft command and data system and attitude control system require a continuous source of backup power during all anticipated power bus fault scenarios. Power for the Jupiter Probe is conditioned, isolated, and controlled by a Probe interface subassembly. Flight performance of the spacecraft and the PMAD has been successful to date, with no major anomalies.

Detwiler, R. C.; Smith, R. L.

1990-01-01

143

Distributed generation power inverters as shunt active power filters for losses minimization in the distribution network  

Microsoft Academic Search

This paper evaluates the benefits that can be achieved in the operation of LV distribution networks with a large penetration of distributed generation when the inverters that interface with the network are used as shunt active power filters to reduce the zero sequence current component generated by unbalanced loads. For that purpose, a typical urban distribution network has been simulated

E. Belenguer; H. Beltran; N. Aparicio

2007-01-01

144

A power electronic-based distribution transformer  

Microsoft Academic Search

The distribution transformer has been in use by utilities throughout the twentieth century. Until now, it has consisted of a configuration of iron or steel cores and copper\\/aluminum coils, with mineral oil serving as both coolant and dielectric medium. Inherent in this type of construction are regulation, significant weight, losses, environmental concerns, and power quality issues. For the 21st century,

Edward R. Ronan; Scott D. Sudhoff; Steven F. Glover; Dudley L. Galloway

2002-01-01

145

Distributed sleep transistors network for power reduction  

Microsoft Academic Search

Sleep transistors are effective to reduce dynamic and leakage power. The cluster-based design was proposed to reduce the sleep transistor area by clustering gates to minimize the simultaneous switching current per cluster and then inserting a sleep transistor per cluster. In the paper, we propose a novel distributed sleep transistor network (DSTN), and show that DSTN is intrinsically better than

Changbo Long; Lei He

2003-01-01

146

Distributed sleep transistor network for power reduction  

Microsoft Academic Search

Sleep transistors are effective to reduce dynamic and leakage power. The cluster-based design was proposed to reduce the sleep transistor area by clustering gates to minimize the simultaneous switching current per cluster and then inserting a sleep transistor per cluster. In the paper, we propose a novel distributed sleep transistor network (DSTN), and show that DSTN is intrinsically better than

Changbo Long; Lei He

2003-01-01

147

Distributed sleep transistor network for power reduction  

Microsoft Academic Search

Sleep transistors are effective to reduce leakage power during standby modes. The cluster-based design was proposed to save sleep transistor area by clustering gates to minimize the simultaneous switching current per cluster and inserting a sleep transistor per cluster. In this paper, we propose a novel distributed sleep transistor network (DSTN), and show that DSTN is intrinsically better than the

Changbo Long; Lei He

2004-01-01

148

Optimal power flow in radial distribution systems  

Microsoft Academic Search

Radial distribution systems (RDS) have lines with high R\\/X ratios and hence Newton based methods were not reliable to solve their set of bus power balance equations. Historically, a recursive solution method using a set of voltage equations and its variants are very popular to determine a voltage solution of a RDS. Consequently, use of classical optimization was not possible.

B. Venkatesh

2010-01-01

149

The MESSENGER Power Distribution Unit packaging design  

Microsoft Academic Search

A Power Distribution Unit (PDU) is being developed by The Johns Hopkins University Applied Physics Laboratory for the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft that will orbit the planet Mercury for one Earth year to complete the global mapping and the detailed characterization of the planet's exosphere, magnetosphere, surface, and interior. The PDU contains the circuitry for

Binh Q. Le; Sharon X Ling; Larry R. Kennedy; George Dakermanji; Sean C. Laughery

2002-01-01

150

A new method to evaluate alternate AC power source effects in multi-unit nuclear power plants  

Microsoft Academic Search

In order to evaluate accurately a station blackout (SBO) event frequency of a multi-unit nuclear power plant that has a shared alternate AC (AAC) power source, an approach has been developed which accommodates the complex inter-unit behavior of the shared AAC power source under multi-unit loss of offsite power conditions. The SBO frequency at a target unit of probabilistic safety

Woo Sik Jung; Joon-Eon Yang; Jaejoo Ha

2003-01-01

151

Are power-law distributions an equilibrium distribution or a stationary nonequilibrium distribution?  

NASA Astrophysics Data System (ADS)

We examine whether the principle of detailed balance holds for the power-law distributions that are generated from the well-known two-variable Langevin equation and the associated Fokker-Planck equations. With the detailed balance and the generalized fluctuation-dissipation relation, we derive analytically the stationary power-law distribution from the Ito’s, Stratonovich’s and Zwanzig’s Fokker-Planck equations, and conclude that the power-law distributions can either be a stationary nonequilibrium distribution or an equilibrium distribution, which depend on information about the form of the diffusion coefficient function and the existence and uniqueness of an equilibrium state.

Guo, Ran; Du, Jiulin

2014-07-01

152

Efficient Utility Equipment: Power Distribution Systems and Power Conditioning Equipment.  

National Technical Information Service (NTIS)

Air Force bases, having been constructed many years ago, employ old, inefficient power distribution systems. In order to comply with the Energy Policy Act of 1992, the Air Force must reduce energy consumption. One way of doing this is to install more effi...

R. Bernstein

1995-01-01

153

High power GTO AC\\/DC current source converter with minimum switching frequency and maximum power factor  

Microsoft Academic Search

This paper presents a unique PWM switching pattern and a novel power factor control scheme for high power GTO AC\\/DC converters. This switching pattern has a switching frequency of 360 Hz, which is the lowest possible frequency to achieve 5th and 7th harmonic elimination and an adjustable DC output current simultaneously. Using both feedback and feedforward control techniques, the proposed

Y. Xiao; B. Wu; F. DeWinter; R. Sotudeh

1996-01-01

154

High power factor control system in multilevel converters for AC heavy traction drives  

Microsoft Academic Search

A quasi-zero reactive power demand which is mandatory in single-phase AC (25 kV\\/50 Hz) traction systems is considered. Multilevel converter structures and high-performance control techniques have been developed to fulfil this goal in AC heavy traction drives. The tasks of the three level rectifier are described in detail. The current control logic is particularly suitable for applications to multilevel bridges.

T. Ghiara; M. Marchesoni; G. Sciutto

1990-01-01

155

Polygon Connected 15Phase AC-DC Converter for Power Quality Improvement  

Microsoft Academic Search

This paper presents a polygon connected autotransformer based 15-phase AC-DC converter for power quality improvement in vector controlled induction motor drives (VCIMD's). The proposed multi-phase AC-DC converter is based on a polygon connected autotransformer, designed for producing 15-phase voltages for effective harmonic reduction. The effect of load variation on drive is also studied to demonstrate the effectiveness of the proposed

Bhim Singh; Vipin Garg; G. Bhuvaneswari

2006-01-01

156

Power Quality Improvements Using Delta-Polygon Connected Autotransformer Based Nine Phase AC-DC Converter  

Microsoft Academic Search

This paper deals with a novel delta-polygon connected autotransformer based improved power quality nine-phase ac-dc converter feeding vector controlled induction motor drives (VCIMD's). The design of the proposed autotransformer is presented along with the necessary modifications required for making it suitable for retrofit applications, where presently a 6-pulse diode bridge rectifier is used. The proposed ac-dc converter is found capable

B. Singh; V. Garg; G. Bhuvaneswari

2006-01-01

157

Polygon connected autotransformer based 24-pulse AC-DC converter for power quality improvement  

Microsoft Academic Search

This paper deals with a polygon connected autotransformer based 24-pulse AC-DC converter for power quality improvement in vector controlled induction motor drives (VCIMD's). A polygon connected autotransformer with multi windings per phase at different phase angles is used to realize the proposed 24-pulse AC-DC converter. The design of proposed autotransformer is presented along with the necessary modifications required for making

B. Singh; V. Garg; G. Bhuvaneswari

2006-01-01

158

New bidirectional sinewave-modulated series resonant power conditioning system with high-frequency AC link  

Microsoft Academic Search

The authors describe a novel conceptual multistage topology of a sinewave-modulated DC-LFAC (DC-low-frequency AC) power conversion conditioning and processing system, which incorporate a phase-shifting PWM (pulsewidth modulation) series-resonant cycloinverter (inverter-coupled cycloconverter cascade circuit) with a high-frequency AC (HFAC) transformer link. Its advanced hardware of system control implementation uses instantaneous sinewave-modulated voltage regulation and compensation strategies, depending upon load disturbance and

H. Yonemori; Y. Nishida; M. Nakaoka

1989-01-01

159

A novel single-phase AC\\/DC converter for power factor correction  

Microsoft Academic Search

A novel single-phase AC\\/DC converter with two pulsewidth modulation (PWM) schemes is proposed to draw a sinusoidal line current with nearly unity power factor, achieve balanced neutral point voltage and regulate the do bus voltage. With the aid of neutral point clamped scheme, a three-level voltage pattern will be generated on the AC side of the proposed rectifier. To track

Bor-Ren Lin; Shih-Jung Huang; Tsung-Liang Hung

2002-01-01

160

Harmonic analysis of multi-phase electric-power distribution systems  

Microsoft Academic Search

This study presents a computer program as a tool for the harmonic analysis of multi-phase electric power distribution systems. In the program, the source of harmonics can be any number of multi-phase harmonic currents and\\/or voltages, or up to 10 three-phase converts. Frequency-dependent models of ac network elements are assembled into a sparse admittance matrix. Then, sparsity techniques are employed

Hosseini

1988-01-01

161

Unity Power Factor Control in Three-Phase AC\\/DC Boost Converter Using Sliding Modes  

Microsoft Academic Search

A problem of power factor correction for a class of three-phase boost ac\\/dc power converters is addressed in this paper. A full-bridge hardware topology is studied and used to address the basics of the efficient power conversion with high values of power factor. The sliding mode control drives the output voltage to the desired dc level in the presence of

Yuri Shtessel; Simon Baev; Haik Biglari

2008-01-01

162

Improved transistorized AC motor controller for battery powered urban electric passenger vehicles  

NASA Astrophysics Data System (ADS)

An ac motor controller for an induction motor electric vehicle drive system was designed, fabricated, tested, evaluated, and cost analyzed. A vehicle performance analysis was done to establish the vehicle tractive effort-speed requirements. These requirements were then converted into a set of ac motor and ac controller requirements. The power inverter is a three-phase bridge using power Darlington transistors. The induction motor was optimized for use with an inverter power source. The drive system has a constant torque output to base motor speed and a constant horsepower output to maximum speed. A gear shifting transmission is not required. The ac controller was scaled from the base 20 hp (41 hp peak) at 108 volts dec to an expanded horsepower and battery voltage range. Motor reversal was accomplished by electronic reversal of the inverter phase sequence. The ac controller can also be used as a boost chopper battery charger. The drive system was tested on a dynamometer and results are presented. The current-controlled pulse width modulation control scheme yielded improved motor current waveforms. The ac controller favors a higher system voltage.

Peak, S. C.

1982-09-01

163

Development of software to improve AC power quality on large spacecraft  

NASA Astrophysics Data System (ADS)

To insure the reliability of a 20 kHz, alternating current (AC) power system on spacecraft, it is essential to analyze its behavior under many adverse operating conditions. Some of these conditions include overloads, short circuits, switching surges, and harmonic distortions. Harmonic distortions can become a serious problem. It can cause malfunctions in equipment that the power system is supplying, and, during distortions such as voltage resonance, it can cause equipment and insulation failures due to the extreme peak voltages. To address the harmonic distortion issue, work was begun under the 1990 NASA-ASEE Summer Faculty Fellowship Program. Software, originally developed by EPRI, called HARMFLO, a power flow program capable of analyzing harmonic conditions on three phase, balanced, 60 Hz AC power systems, was modified to analyze single phase, 20 kHz, AC power systems. Since almost all of the equipment used on spacecraft power systems is electrically different from equipment used on terrestrial power systems, it was also necessary to develop mathematical models for the equipment to be used on the spacecraft. The modelling was also started under the same fellowship work period. Details of the modifications and models completed during the 1990 NASA-ASEE Summer Faculty Fellowship Program can be found in a project report. As a continuation of the work to develop a complete package necessary for the full analysis of spacecraft AC power system behavior, deployment work has continued through NASA Grant NAG3-1254. This report details the work covered by the above mentioned grant.

Kraft, L. Alan

1991-12-01

164

21 CFR 880.5510 - Non-AC-powered patient lift.  

Code of Federal Regulations, 2013 CFR

21 Food and Drugs 8 2013-04-01 2013-04-01... 880.5510 Section 880.5510 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT...non-AC-powered patient lift is a hydraulic, battery, or mechanically powered...

2013-04-01

165

Stability Analysis for HVDC\\/AC Power Systems Based on a Modal Series Method  

Microsoft Academic Search

Modal series methods can be used to represent the dynamic characteristics of a nonlinear system. In this paper the modal series method is applied to investigate the stability and the nonlinear modal interaction in HVDC\\/AC power systems. A comprehensive analytical technique based on the modal series method and symbolic computer algebra is proposed for the analysis of power systems that

X. Y. Li; H. C. Liu; Y. Y. Hu

166

Hardware Model Of A Shipboard Zonal Electrical Distribution System (ZEDS): Alternating Current/Direct Current (AC/DC).  

National Technical Information Service (NTIS)

A hardware model of a shipboard electrical distribution system based on aspects of the DDG 51 Flight IIA, Arleigh Burke class, 60Hz Alternating Current (AC) and the future direct current (DC), zonal electrical distribution system (ZEDS). These distributio...

C. N. Tidd

2010-01-01

167

Independent Orbiter Assessment (IOA): Analysis of the Electrical Power Distribution and Control Subsystem, Volume 2  

NASA Technical Reports Server (NTRS)

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Electrical Power Distribution and Control (EPD and C) hardware. The EPD and C hardware performs the functions of distributing, sensing, and controlling 28 volt DC power and of inverting, distributing, sensing, and controlling 117 volt 400 Hz AC power to all Orbiter subsystems from the three fuel cells in the Electrical Power Generation (EPG) subsystem. Volume 2 continues the presentation of IOA analysis worksheets and contains the potential critical items list.

Schmeckpeper, K. R.

1987-01-01

168

Gibbsian Theory of Power-Law Distributions  

SciTech Connect

It is shown that power-law phase space distributions describe marginally stable Gibbsian equilibria far from thermal equilibrium, which are expected to occur in collisionless plasmas containing fully developed quasistationary turbulence. Gibbsian theory is extended on the fundamental level to statistically dependent subsystems introducing an 'ordering parameter' {kappa}. Particular forms for the entropy and partition functions are derived with superadditive (nonextensive) entropy, and a redefinition of temperature in such systems is given.

Treumann, R. A. [Department of Geophysics and Environmental Sciences, Munich University, D-80333 Munich (Germany); Department of Physics, Dartmouth College, Hanover, New Hampshire 03755 (United States); Jaroschek, C. H. [Department Earth and Planetary Science, University of Tokyo, Tokyo (Japan)

2008-04-18

169

Photovoltaic Power System and Power Distribution Demonstration for the Desert RATS Program  

NASA Technical Reports Server (NTRS)

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.

Colozza, Anthony; Jakupca, Ian; Mintz, Toby; Herlacher, Mike; Hussey, Sam

2012-01-01

170

Power and DC link voltage control considerations for indirect AC\\/AC Modular Multilevel Converters  

Microsoft Academic Search

A highly interesting application field of the Modular Multilevel Converter is the interconnection of the European three-phase 50 Hz industrial grid with the single-phase 16 2 =3 Hz railway supply. Contrary to existing technologies, the utilization of a bulky and costly transformer on the low frequency side as well as additional filtering components on the AC lines or DC link

Michail Vasiladiotis; Stephan Kenzelmann; Nicolas Cherix; Alfred Rufer

2011-01-01

171

A distributed control approach for power and energy management in a notional shipboard power system  

NASA Astrophysics Data System (ADS)

The main goal of this thesis is to present a power control module (PCON) based approach for power and energy management and to examine its control capability in shipboard power system (SPS). The proposed control scheme is implemented in a notional medium voltage direct current (MVDC) integrated power system (IPS) for electric ship. To realize the control functions such as ship mode selection, generator launch schedule, blackout monitoring, and fault ride-through, a PCON based distributed power and energy management system (PEMS) is developed. The control scheme is proposed as two-layer hierarchical architecture with system level on the top as the supervisory control and zonal level on the bottom as the decentralized control, which is based on the zonal distribution characteristic of the notional MVDC IPS that was proposed as one of the approaches for Next Generation Integrated Power System (NGIPS) by Norbert Doerry. Several types of modules with different functionalities are used to derive the control scheme in detail for the notional MVDC IPS. Those modules include the power generation module (PGM) that controls the function of generators, the power conversion module (PCM) that controls the functions of DC/DC or DC/AC converters, etc. Among them, the power control module (PCON) plays a critical role in the PEMS. It is the core of the control process. PCONs in the PEMS interact with all the other modules, such as power propulsion module (PPM), energy storage module (ESM), load shedding module (LSHED), and human machine interface (HMI) to realize the control algorithm in PEMS. The proposed control scheme is implemented in real time using the real time digital simulator (RTDS) to verify its validity. To achieve this, a system level energy storage module (SESM) and a zonal level energy storage module (ZESM) are developed in RTDS to cooperate with PCONs to realize the control functionalities. In addition, a load shedding module which takes into account the reliability of power supply (in terms of quality of service) is developed. This module can supply uninterruptible power to the mission critical loads. In addition, a multi-agent system (MAS) based framework is proposed to implement the PCON based PEMS through a hardware setup that is composed of MAMBA boards and FPGA interface. Agents are implemented using Java Agent DEvelopment Framework (JADE). Various test scenarios were tested to validate the approach.

Shen, Qunying

172

Distribution of injected power fluctuations in electroconvection  

NASA Astrophysics Data System (ADS)

We report on the distribution spectra of the fluctations in the amount of power injected into a liquid crystal undergoing electroconvective flow. The probability distribution functions (PDFs) of the fluctuations as well as the magnitude of the fluctuations have been determined in a wide range of imposed stress both for `unconfined' and `confined' flow geometries. These spectra are compared to those found in other systems held far from equilibrium, and find that in certain conditions we obtain the ''universal'' PDF form reported by S.T. Bramwell et al., [Phys. Rev. Lett. 84, 3744 (2000)]. Moreover, the PDF approaches this universal form via an interesting mechanism whereby the distribution's negative tail evolves towards form in a different manner than the positive tail.

Tóth-Katona, Tibor; Gleeson, J. T.

2004-03-01

173

Distribution of injected power fluctuations in electroconvection.  

PubMed

We report on the distribution spectra of the fluctations in the amount of power injected into a liquid crystal undergoing electroconvective flow. The probability distribution functions (PDFs) of the fluc-tuations as well as the magnitude of the fluctuations have been determined in a wide range of imposed stress both for unconfined and confined flow geometries. These spectra are compared to those found in other systems held far from equilibrium, and find that in certain conditions we obtain the universal PDF form reported by Phys. Rev. Lett. 84, 3744 (2000)]. Moreover, the PDF approaches this universal form via an interesting mechanism whereby the distribution's negative tail evolves towards form in a different manner than the positive tail. PMID:14754056

Tóth-Katona, Tibor; Gleeson, J T

2003-12-31

174

Distribution of Injected Power Fluctuations in Electroconvection  

NASA Astrophysics Data System (ADS)

We report on the distribution spectra of the fluctations in the amount of power injected into a liquid crystal undergoing electroconvective flow. The probability distribution functions (PDFs) of the fluc­tuations as well as the magnitude of the fluctuations have been determined in a wide range of imposed stress both for unconfined and confined flow geometries. These spectra are compared to those found in other systems held far from equilibrium, and find that in certain conditions we obtain the universal PDF form reported by

S. T. Bramwell et al. [Phys. Rev. Lett. 84, 3744 (2000)]
. Moreover, the PDF approaches this universal form via an interesting mechanism whereby the distribution's negative tail evolves towards form in a different manner than the positive tail.

Tóth-Katona, Tibor; Gleeson, J. T.

2003-12-01

175

Radial Distribution Systems Power Flow with Distributed Generation: Modified Power Summation Method  

Microsoft Academic Search

In this work, the Power Summation Method is adapted to be applied in distribution systems that include distributed generation. The voltage control at the generation buses is treated as an optimization problem, which uses the Newton-Raphson method as the minimization technique. The algorithm is iterative and includes the reactive and voltage limits constraints for each generator. The accuracy and computational

Benemar Alencar de Souza; Helon David de Macedo Braz; Joao Marcelo Cavalcante de Albuquerque; Julio Guilherme Gerlach Gutterres

2006-01-01

176

System for transmitting low frequency analog signals over AC power lines  

DOEpatents

A system for transmitting low frequency analog signals over AC power lines using FM modulation. A low frequency analog signal to be transmitted is first applied to a voltage-to-frequency converter where it is converted to a signal whose frequency varies in proportion to the analog signal amplitude. This signal is then used to modulate the carrier frequency of an FM transmitter coupled to an AC power line. The modulation signal frequency range in selected to be within the response band of the FM transmitter. The FM modulated carrier signal is received by an FM receiver coupled to the AC power line, demodulated and the demodulated signal frequency is converted by a frequency-to-voltage converter back to the form of the original low frequency analog input signal.

Baker, Steven P. (Powell, TN); Durall, Robert L. (Lenoir City, TN); Haynes, Howard D. (Knoxville, TN)

1989-01-01

177

A system for tranmitting low frequency analog signals over ac power lines  

DOEpatents

A system for transmitting low frequency analog signals over ac power lines using FM modulation. A low frequency analog signal to be transmitted is first applied to a voltage-to-frequency converter where it is converted to a signal whose frequency varies in proportion to the analog signal amplitude. This signal is then used to modulate the carrier frequency of an FM transmitter coupled to an ac power line. The modulation signal frequency range is selected to be within the response band of the FM transmitter. The FM modulated carrier signal is received by an FM receiver coupled to the ac power line, demodulated and the demodulated signal frequency is converted by a frequency-to-voltage converter back to the form of the original low frequency analog input signal. 4 figs.

Baker, S.P.; Durall, R.L.; Haynes, H.D.

1987-07-30

178

A New Power Flow Method in Radial Distribution Systems  

Microsoft Academic Search

In this paper, a new efficient method is proposed for power flow calculation in radial distribution systems. The distribution busines is changing the need to plan and respond to technical change, growth in distributed generation and deregulated power markets. Thus, it is important to improve fundamental analytical tools in distribution systems. This paper proposes a new method for the power

Wataru Ohyoshi; Hiroyuki Mori

2006-01-01

179

Competition and Cooperation of Distributed Generation and Power System  

Microsoft Academic Search

Advances in distributed generation technologies together with the deregulation of an electric power industry can lead to a massive introduction of distributed generation. Since most of distributed generation will be interconnected to a power system, coordination and competition between distributed generators and large-scale power sources would be a vital issue in realizing a more desirable energy system in the future.

Masatoshi Miyake; Toshiya Nanahara

2005-01-01

180

System for conveniently providing load testing termination of an AC power source having at least one battery  

NASA Astrophysics Data System (ADS)

An AC uninterruptible power source is disclosed that provides multiphase power output signals for actual use and a selectable single phase power output signal for use in testing. The AC uninterruptible power source further comprises at least one battery. The single phase output signal is connected to a dummy load by means of a power switch of the break before make type. The invention further includes the dummy load as preferably having metering capabilities to measure the frequency, current, and voltage parameters of the single phase output signal. The arrangement of the present invention allows for the single phase output to be mated to the dummy load without the need of removing input power to the AC uninterruptible power source so as to reduce, or even eliminate, transient caused failures to the AC uninterruptible power source and to its sensitive load equipment which the power source services.

Morell, Wilbert J., III

1995-05-01

181

Impact of Renewable Distributed Generation on Power Systems  

Microsoft Academic Search

The traditional approach in electric power generation is to have centralized plants distributing electricity through an extensive transmission & distribution network. Distributed generation (DG) provides electric power at a site closer to the customer, eliminating the unnecessary transmission and distribution costs. In addition, it can reduce fossil fuel emissions, defer capital cost, reduce maintenance investments and improve the distribution feeder

Miroslav Begovic; Aleksandar Pregelj; Ajeet Rohatgi; Damir Novosel

2001-01-01

182

Improved transistorized ac motor controller for battery powered urban electric passenger vehicles  

SciTech Connect

The objectives of this program for an improved ac motor controller for battery powered urban electric passenger vehicles were: the design, fabrication, test, evaluation and cost analysis of an engineering model controller for an ac induction motor drive system, the investigation of a power level expansion to a family of horsepower and battery system voltages, and the investigation of the applicability of the ac controller for use as an on-board battery charger and for providing the function of motor reversal. Additional vehicle specifications, e.g., acceleration and pulling out of potholes, were added to the NASA vehicle specifications. Then, a vehicle performance analysis was done to establish the vehicle tractive effort-speed requirements. These requirements were then converted into a set of ac motor and ac controller requirements. The General Electric ac induction motor used in the drive is optimized to operate as a vehicle traction motor with a pulse width modulated (PWM) inverter as a power source. The motor is nominally rated 20 hp and 41 hp peak. The power inverter design is a three-phase transistorized bridge configuration with feedback diodes. The transistors are a special design General Electric high-power Darlington transistor rated 450 volts and 200 amps. The battery system voltage chosen was 108 volts. The control strategy is a constant torque profile by PWM operation to base speed and a constant horsepower profile by square-wave operation to maximum speed. A gear shifting transmission is not required. An advanced current-controlled PWM technique is used to control the motor voltage. The primary feedback control is a motor angle control, with voltage and torque outer loop controls.

Peak, S.C.

1982-09-01

183

Interaction of lightning with power distribution lines  

NASA Astrophysics Data System (ADS)

Triggered-lightning experiments were conducted in 1996, 1999, and 2000 to study the responses of overhead power distribution lines to lightning at the International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, Florida. The lightning was artificially initiated (triggered) from natural thunderclouds using the rocket-and-wire technique, and its current was directed to a phase conductor at midspan or at a pole near the center of the line. Experimental results and associated EMTP modeling are presented in this dissertation for the following line configurations: (1)a two-conductor, 740-m overhead distribution line with 2 arrester stations in 1996; (2)a four- conductor, 245-m overhead distribution line with 2 arrester stations in 1999; and (3)a four-conductor, 829-m overhead distribution line with 6 arrester stations in 2000. The three-phase lines tested in 1999 and 2000 were standard designs of a major Florida power company. Lightning peak currents injected into the lines ranged from 7 to 57 kA. Voltages and currents were measured at various locations along the line. Video and photographic cameras were used to image lightning channels and detect line flashovers. The significant results of the research are (1)flashovers between conductors were observed, both accompanied and not accompanied by arrester failures, (2)an arrester failed on seven of eight direct lightning strikes to the line in 2000, (3)arcing between conductors may prevent failures of arresters connected to the struck phase, (4)the bulk of the lightning current flows from the struck phase to neutral through the arresters closest to the strike point, (5)the withstand energy of the arresters can be exceeded due to the contribution from multiple strokes and/or relatively low-level, long-lasting current components, (6)the distribution of charge transferred to ground among multiple neutral grounds, which is determined by low-frequency, low-current grounding resistances is different from the distribution of peak currents to ground, which is characterized by a rapid decrease of current with increasing distance from the strike point, (7)EMTP allows one to model the observed line behavior with reasonable accuracy, (8)overall, the standard lightning protection of the distribution lines tested does not appear to be adequate.

Mata, Carlos Tomas

184

Three-phase, power quality improvement ac\\/dc converters  

Microsoft Academic Search

The generation of harmonics and reactive power flow in a power system is greatly influenced by the widespread use of power electronic converters in addition to other sources of harmonics and reactive power. The design, development and successful application of single-phase, power quality improvement converters in domestic, commercial and industrial environment has made possible the design and development of three-phase,

Abdul Hamid Bhat; Pramod Agarwal

2008-01-01

185

High frequency link DC\\/AC converters using three phase output PWM cycloconverters for uninterruptible power supplies  

Microsoft Academic Search

The authors propose a main circuit and a control method of a high-frequency link DC\\/AC power converter with three-phase output using a cycloconverter which converts a high-frequency voltage into a three-phase commercial frequency voltage. This DC\\/AC converter can control the flow of power bidirectionally, and can charge a DC power supply and compensate for instantaneous reactive power. Simulations and experiments

K. Inagaki; S. Okuma

1991-01-01

186

Development of software to improve AC power quality on large spacecraft  

NASA Technical Reports Server (NTRS)

To insure the reliability of a 20 kHz, AC power system on spacecraft, it is essential to analyze its behavior under many adverse operating conditions. Some of these conditions include overloads, short circuits, switching surges, and harmonic distortions. Harmonic distortions can cause malfunctions in equipment that the power system is supplying, and during extreme distortions such as voltage resonance, it can cause equipment and insulation failures due to the extreme peak voltages. HARMFLO, a power flow computer program, which was capable of analyzing harmonic conditions on three phase, balanced, 60 Hz, AC power systems, was modified to analyze single phase, 20 kHz, AC power systems. Since almost all of the equipment used on spacecraft power systems is electrically different from equipment used on terrestrial power systems, it was also necessary to develop mathematical models for the equipment to be used on the spacecraft. The results are that (1) the harmonic power now has a model of a single phase, voltage controlled, full wave rectifier; and (2) HARMFLO was ported to the SUN workstation platform.

Kraft, L. Alan

1991-01-01

187

Test report light duty utility arm power distribution system (PDS)  

SciTech Connect

The Light Duty Utility Arm (LDUA) Power Distribution System has completed vendor and post-delivery acceptance testing. The Power Distribution System has been found to be acceptable and is now ready for integration with the overall LDUA system.

Clark, D.A.

1996-03-04

188

DC Micro-grid for Super High Quality Electric Power Distribution  

NASA Astrophysics Data System (ADS)

“DC Micro-grid" is a novel power system using dc distribution in order to provide a super high quality electric power. The dc distribution system is suitable for dc output type distributed generations such as photovoltaic and fuel cells, and energy storages such as batteries and electric double layer capacitors. Power is distributed through dc distribution line and converted to required ac or dc voltage by converters placed near loads. The load side converters do not need transformers by choosing proper distributed dc voltage. The spread scheme of converters contributes to provide a high quality power supplying. Even if a short circuit occurs at one load side, it does not effect other loads. In this paper, we propose a configuration of DC micro-grid and control methods of converters for generations and energy storages. Computer simulation results demonstrated the seamless operation during turn-on and turn-off of a distributed generation, the transient of connecting and disconnecting operation with bulk power system, and the stability against a sudden large load variation.

Kakigano, Hiroaki; Miura, Yushi; Ise, Toshifumi; Uchida, Ryohei

189

Power factor control system for ac induction motors  

NASA Technical Reports Server (NTRS)

A power control circuit for an induction motor is disclosed in which a servo loop is used to control power input by controlling the power factor of motor operation. The power factor is measured by summing the voltage and current derived square wave signals.

Nola, F. J. (inventor)

1981-01-01

190

Harmonics in DC to AC converters of single phase uninterruptible power supplies  

Microsoft Academic Search

Single phase uninterruptible power supplies (UPS) employ an inverter for DC to AC conversion. Advanced inverters consist of a full bridge transistor topology and an LC filter. An optimal inverter performance can be achieved if the output voltage is controlled by unipolar pulse width modulation (PWM). The paper describes the influence of the unipolar PWM on the voltages and the

H. Van der Broeck; M. Miller

1995-01-01

191

33. A.C. PANEL FOR MENTONE POWER HOUSE, P.L. & P. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

33. A.C. PANEL FOR MENTONE POWER HOUSE, P.L. & P. CO., LOS ANGELES. RETRACED FROM MASSON'S DRAWING NO. C-275. JAN. 20, 1909. SCE drawing no. 52880. - Santa Ana River Hydroelectric System, SAR-3 Powerhouse, San Bernardino National Forest, Redlands, San Bernardino County, CA

192

AC Resonant Charging for Interfacing Prime Power to Pulse Conditioning Circuits.  

National Technical Information Service (NTIS)

The impact on a prime power source due to AC resonant charging was investigated. The source was a standard DOD 15 KW, 400 Hz alternator. Adverse impact on the alternator was almost negligible for a varying load of 15 to 60 KW and a frequency change of 380...

W. C. Dungan

1981-01-01

193

Analysis of power losses in AC\\/DC-converter for electric vehicle drive  

Microsoft Academic Search

In this paper the power losses of an AC\\/DC- converter for an electric vehicle drive are analyzed. A validated model which calculates the losses analytically based on forward parameters and switching losses maps is used to design two converters, one for a standard machine and another for an energy efficiency optimized machine. With this a losses reduction of 25% can

Klaus Muehlbauer; Fabian Bachl; Dieter Gerling

2011-01-01

194

A high frequency link direct dc-ac converter for residential fuel cell power systems  

Microsoft Academic Search

This paper describes a boost converter cascaded high frequency link direct dc-ac converter suitable for fuel cell power sources. A new multi-loop control for a boost converter to reduce the low frequency input current harmonics drawn from the fuel cell is proposed. A new PWM technique for the cycloconverter at the secondary to reject the low order harmonics in the

Yu Jin Song; Prasad N. Enjeti

2004-01-01

195

Design and control of a low power DC-AC converter fed by a photovoltaic array  

Microsoft Academic Search

In this paper, we present a DC-AC converter fed by a PV array for stand alone applications up to 50 W. It is dedicated to rural areas in countries having abundant sunshine and where there is no grid connection to the utility network or the power supply is weak as in many underdeveloped countries. Using a single PV array of

F. Belkacem; D. Diallo; G. A. Capolino

2004-01-01

196

New Power Factor Correction AC-DC Converter With Reduced Storage Capacitor Voltage  

Microsoft Academic Search

Most of single-stage power factor correction (PFC) ac-dc converters usually present a high voltage swing on the storage capacitor. That means, high size and cost of the storage capacitor is obtained. The Series Inductance Interval (SII) PFC converters allow reducing cost and size of the storage capacitor since the capacitor voltage is lower than the output voltage and, therefore, the

Antonio Lazaro; Andrés Barrado; Marina Sanz; Vicente Salas; Emilio Olias

2007-01-01

197

Formulation of Oligopolistic Competition in AC Power Networks: An NLP Approach  

Microsoft Academic Search

In this paper, oligopolistic competition in a centralized power market is characterized by a multi-leader single-follower game, and formulated as a nonlinear programming (NLP) problem. An ac network is used to represent the transmission system and is modeled using rectangular coordinates. The follower is composed of a set of competitive suppliers, demands, and the system operator, while the leaders are

Guillermo Bautista; Miguel F. Anjos; Anthony Vannelli

2007-01-01

198

Simulation studies of JeJu AC power system modeling by using PSCAD\\/EMTDC  

Microsoft Academic Search

This paper represents the developments of the PSCAD\\/EMTDC based JEJU AC power systems and HVDC equivalent modeling. First, the background of the development and its associated technologies, such as PSCAD\\/EMTDC based generator, exciter and governor modeling are introduced. And then after the modeling has been established, the transient analysis and fault analysis have been done by using PSCAD in order

Zang Shuai; Joon-Ho Choi; Hae-kon Nam

2009-01-01

199

Research on reciprocal power-fed AC drive test rig for electric traction applications  

Microsoft Academic Search

This paper presents a reciprocal power-fed AC drive test rig for electric traction applications. Two inverter-fed induction motors on a common shaft are used in this test rig. One is as the drive motor, and the other is as the load motor. The DC links of both inverters are connected to each other to circulate the energy, and supplied from

Zhiwen Ma; Trillion Zheng; Fei Lin

2005-01-01

200

Power Flow Analysis for Balanced and Unbalanced Radial Distribution Systems  

Microsoft Academic Search

This paper reports on an efficient method of power flow analysis for solving balanced and unbalanced radial distribution systems. The radial distribution system is modelled as a series of interconnected single feeders. Using Kirchoff's laws, a set of iterative power flow equations was developed to conduct the power flow studies. Due to the voltage dependency of loads in distribution systems,

H. M. Mok; S. Elangovan; M. M. A. Salama; Cao Longjian

201

Robust distribution and use of electric power  

NASA Astrophysics Data System (ADS)

One of the major problems related to the simultaneous operation of electrical converters in a wide open power system is the concordance between the characteristics of the feeder itself and the load. Nowadays we usually call Electric Power Quality or Electromagnetic Compatibility to this Concordance Degree. Currently, the most important non concordance are voltage sag (voltage dip) and short time interruptions, that is: decreasings in voltage RMS value lasting from some tenths of a second to several seconds. Current analysis usually study this problem from the feeder side, by means of morphological or stadistical approaches, or from the load side in order to evaluate immunity, emission or specific solutions. This line of research, undoubtly needed provided we need to know the current state of the power system and to increase the concordance degree, is not enough because of the huge variability between power lines and from one instant to another. Moreover, the legal boundaries that can support business decisions are not developed yet. The proposed new theory is widely contrasted by field and laboratory measurement. Detailed analysis include instant voltage, instant current, power system and load effects from many places inside the power system of Spain. This theory is a novel approach to the determination of Concordance Degree (CG) of a whole system (be it a distribution line or a single machine) and to the corrective steps needed to increase it. In addition, the proposed model allow a quantitative evaluation of corrective actions like the increase of energy system storage (in a mechanical to electrical convertible form) or/and the increase of the supplied reactive power. Profitability of corrective actions is mainly a function of the number of voltage dips (sags) and short time interruptions that happen in a given period of time. To reduce this number we have studied and developed new fault characterization and location algorithms designed specifically for medium voltage networks. These algorithms, applied to the recorded faults obtained in the widespread measure campaign we have performed, have allowed the analysis of the Fault Repeatness. Last, new lines of research are suggested, mainly focused on more detailed analytical models together with laboratory and field experiences, in order to provide a solid ground for the development of a realistic standard environment able to provide the highest Concordance Degree at the lowest system-as-a-whole cost.

Catalan Izquierdo, Saturnino

2001-07-01

202

Integration of distributed energy sources with electrical power grid  

Microsoft Academic Search

The changes that have been taking place recently in the power sector, lead to an increasing share of distributed generation (DG) in the electric power production. Many different energy sources can be distinguished in this area and majority of them incorporate power electronic electrical energy converters interfacing with a power system. Connection of a large number of distributed energy sources

I. WASIAK; Z. HANZELKA

203

Electrical power distribution on space based radar satellites  

Microsoft Academic Search

The radar payload on a space-based radar (SBR) satellite could require tens of kilowatts of power distributed to many small loads over a large area. This poses special problems for the power distribution and control system (PDCS). A study that examined the power requirements of an SBR spacecraft is reported. A baseline prime power system, generating about 30 kW, was

M. H. Moody; C. A. Maskell

1989-01-01

204

Power System Concepts for the Lunar Outpost: A Review of the Power Generation, Energy Storage, Power Management and Distribution (PMAD) System Requirements and Potential Technologies for Development of the Lunar Outpost  

NASA Technical Reports Server (NTRS)

This paper will review potential power system concepts for the development of the lunar outpost including power generation, energy storage, and power management and distribution (PMAD). In particular, the requirements of the initial robotic missions will be discussed and the technologies considered will include cryogenics and regenerative fuel cells (RFC), AC and DC transmission line technology, high voltage and low voltage power transmission, conductor materials of construction and power beaming concepts for transmitting power to difficult to access locations such as at the bottom of craters. Operating conditions, component characteristics, reliability, maintainability, constructability, system safety, technology gaps/risk and adaptability for future lunar missions will be discussed for the technologies considered.

Khan, Z.; Vranis, A.; Zavoico, A.; Freid, S.; Manners, B.

2006-01-01

205

Smart grid power system control in distributed generation environment  

Microsoft Academic Search

This paper discusses the general aspects of smart grids and focuses on some distribution level smart grid features, such as interconnection of distributed generation and active distribution management, using automated meter reading (AMR) systems in network management and power quality monitoring, application of power electronics in electricity distribution, plug-in vehicles as part of smart grids, and frequency based load control

Pertti Järventausta; Sami Repo; Antti Rautiainen; Jarmo Partanen

2010-01-01

206

Distributed generation power system modeling in nonlinear Hamiltonian form  

Microsoft Academic Search

Distributed generation has dramatically changed the structure of modern power systems. In this structure, power electronic devices are extensively used providing the possibility of new control strategies in the distribution network. To implement these strategies, a complete dynamic analysis of the distributed generation system is needed. In this paper, exploiting a common feature of almost all the distributed generation components

Konstantinos F. Krommydas; George C. Konstantopoulos; Michael K. Bourdoulis; Antonio T. Alexandridis

2012-01-01

207

A GTO powered AC drive system increases the performance of off-highway haul trucks  

Microsoft Academic Search

Existing DC diesel-electric drive systems for off highway haul trucks are at the limits of economical feasibility due to high maintenance costs and power, speed and space constraints of their DC traction motors. Large-scale introduction of AC drives in the rail transportation sector has made compact, powerful, and rugged inverter drives economically viable for the specialty, off-highway hauler market. This

G. M. Brown; W. G. Koellner

1999-01-01

208

Distributed algorithms for monitoring and control of electric power transmission and distribution systems  

Microsoft Academic Search

The benefits of distributed computing systems are massively increased computing power and improved reliability. Distributed computing systems are particularly attractive for monitoring and control of large-scale electric power transmission and distribution systems. In this dissertation two aspects of distributed computing have been investigated. First, a distributed software model for the implementation of network security functions in energy management systems is

Neyer

1989-01-01

209

Long-Lifetime Power Inverter for Photovoltaic AC Modules  

Microsoft Academic Search

This paper presents a power inverter tailored for low-power photovoltaic (PV) systems. The inverter features high reliability, thanks to a circuit topology that obviates aluminum electrolytic capacitors from the circuit. Moreover, all components, including logic and control, have been designed to exhibit high reliability at high temperatures. Three conversion stages form the power topology. First, a full bridge connected to

Cuauhtemoc Rodriguez; Gehan A. J. Amaratunga

2008-01-01

210

Satellite control of electric power distribution  

NASA Technical Reports Server (NTRS)

An L-band frequencies satellite link providing the medium for direct control of electrical loads at individual customer sites from remote central locations is described. All loads supplied under interruptible-service contracts are likely condidates for such control, and they can be cycled or switched off to reduce system loads. For every kW of load eliminated or deferred to off-peak hours, the power company reduces its need for additional generating capacity. In addition, the satellite could switch meter registers so that their readings automatically reflected the time of consumption. The system would perform load-shedding operations during emergencies, disconnecting large blocks of load according to predetermined priorities. Among the distribution operations conducted by the satellite in real time would be: load reconfiguration, voltage regulation, fault isolation, and capacitor and feeder load control.

Bergen, L.

1981-01-01

211

Development of AC and DC Power Supply Direct Interface Converter  

NASA Astrophysics Data System (ADS)

This paper proposes a novel control method for a direct interface converter for management of the energy flow in either an AC or DC supply. The proposed converter is constructed based on an indirect matrix converter. Therefore a proposed control strategy is based on an indirect control method with a triangular carrier wave. The basic operation of the proposed control method is confirmed by experimental results. In addition, this paper also proposes a commutation error compensation method of an output voltage error and an input current error for an indirect matrix converter. In the proposed method, the output voltage and input current error by the commutation can be compensated at the same time, because the PWM pulse of each switch is directly compensated. The validity of the proposed method is confirmed by experimental results. Those results prove that the proposed compensation method can decrease total harmonic distortion (THD) of the input and output current.

Kato, Koji; Itoh, Jun-Ichi

212

Patch Network for Power Allocation and Distribution in Smart Materials  

NASA Technical Reports Server (NTRS)

The power allocation and distribution (PAD) circuitry is capable of allocating and distributing a single or multiple sources of power over multi-elements of a power user grid system. The purpose of this invention is to allocate and distribute power that is collected by individual patch rectennas to a region of specific power-user devices, such as actuators. The patch rectenna converts microwave power into DC power. Then this DC power is used to drive actuator devices. However, the power from patch rectennas is not sufficient to drive actuators unless all the collected power is effectively used to drive another group by allocation and distribution. The power allocation and distribution (PAD) circuitry solves the shortfall of power for devices in a large array. The PAD concept is based on the networked power control in which power collected over the whole array of rectennas is allocated to a sub domain where a group of devices is required to be activated for operation. Then the allocated power is distributed to individual element of power-devices in the sub domain according to a selected run-mode.

Golembiewski, Walter T.

2000-01-01

213

ACS imaging of star clusters in M 51. I. Identification and radius distribution  

NASA Astrophysics Data System (ADS)

Context: Size measurements of young star clusters are valuable tools to put constraints on the formation and early dynamical evolution of star clusters. Aims: We use HST/ACS observations of the spiral galaxy M 51 in F435W, F555W and F814W to select a large sample of star clusters with accurate effective radius measurements in an area covering the complete disc of M 51. We present the dataset and study the radius distribution and relations between radius, colour, arm/interarm region, galactocentric distance, mass and age. Methods: We select a sample of 7698 (F435W), 6846 (F555W) and 5024 (F814W) slightly resolved clusters and derive their effective radii (R_eff) by fitting the spatial profiles with analytical models convolved with the point spread function. The radii of 1284 clusters are studied in detail. Results: We find cluster radii between 0.5 and ~10 pc, and one exceptionally large cluster candidate with R_eff = 21.6 pc. The median R_eff is 2.1 pc. We find 70 clusters in our sample which have colours consistent with being old GC candidates and we find 6 new “faint fuzzy” clusters in, or projected onto, the disc of M 51. The radius distribution can not be fitted with a power law similar to the one for star-forming clouds. We find an increase in R_eff with colour as well as a higher fraction of clusters with B-V ? 0.05 in the interarm regions. We find a correlation between R_eff and galactocentric distance (RG) of the form R_eff? RG0.12±0.02, which is considerably weaker than the observed correlation for old Milky Way GCs. We find weak relations between cluster luminosity and radius: R_eff? L0.15±0.02 for the interarm regions and R_eff? L-0.11±0.01 for the spiral arm regions, but we do not observe a correlation between cluster mass and radius. Conclusions: The observed radius distribution indicates that shortly after the formation of the clusters from a fractal gas, the radii of the clusters have changed in a non-uniform way. We find tentative evidence suggesting that clusters in spiral arms are more compact. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Institute. STScI is operated by the association of Universities for Research in Astronomy, Inc., under the NASA contract NAS 5-26555.

Scheepmaker, R. A.; Haas, M. R.; Gieles, M.; Bastian, N.; Larsen, S. S.; Lamers, H. J. G. L. M.

2007-07-01

214

Importance of distribution automation system for Indian power utility  

Microsoft Academic Search

After restructuring & reformation of Power Utility Sector in India through enactment of Electricity Act 2003, the Power Distribution Utilities are facing tremendous challenges to comply regulatory norms as the distribution networks of Indian Power Utility have grown more than double in size and complexity in the last 10-15 years. It has resulted in increase in volume of workload and

R. N. Lahiri; Arup Sinha; S. P. Chowdhury; C. T. Gaunt

2009-01-01

215

Application for fault location in electrical power distribution systems  

Microsoft Academic Search

Fault location has been studied deeply for transmission lines due to its importance in power systems. Nowadays the problem of fault location on distribution systems is receiving special attention mainly because of the power quality regulations. In this context, this paper presents an application software developed in Matlabtrade that automatically calculates the location of a fault in a distribution power

S. Herraiz; J. Melendez; G. Ribugent; J. Sanchez; M. Castro

2007-01-01

216

Fast decoupled power flow for unbalanced radial distribution systems  

Microsoft Academic Search

This paper presents a novel power flow formulation and an effective solution method for general unbalanced radial distribution systems. Comprehensive models are considered including lines, switches, transformers, shunt capacitors, cogenerators, and several types of loads. A new problem formulation of three-phase distribution power flow equations taking into account the radial structure of the distribution network is presented. A distinguishing feature

Ray D. Zimmerman; Hsiao-Dong Chiang

1995-01-01

217

Improved SCR ac Motor Controller for Battery Powered Urban Electric Vehicles  

NASA Technical Reports Server (NTRS)

An improved ac motor controller, which when coupled to a standard ac induction motor and a dc propulsion battery would provide a complete electric vehicle power train with the exception of the mechanical transmission and drive wheels was designed. In such a system, the motor controller converts the dc electrical power available at the battery terminals to ac electrical power for the induction motor in response to the drivers commands. The performance requirements of a hypothetical electric vehicle with an upper weight bound of 1590 kg (3500 lb) were used to determine the power rating of the controller. Vehicle acceleration capability, top speed, and gradeability requisites were contained in the Society of Automotive Engineers (SAE) Schedule 227a(d) driving cycle. The important capabilities contained in this driving cycle are a vehicle acceleration requirement of 0 to 72.4 kmph (0 to 45 mph) in 28 seconds a top speed of 88.5 kmph (55 mph), and the ability to negotiate a 10% grade at 48 kmph (30 mph). A 10% grade is defined as one foot of vertical rise per 10 feet of horizontal distance.

Latos, T. S.

1982-01-01

218

Distributed Power Balancing for the FREEDM System  

Microsoft Academic Search

The FREEDM microgrid is a test bed for a smart grid integrated with Distributed Grid Intelligence (DGI) to efficiently manage the distribution and storage of renewable energy. Within the FREEDM system, DGI applies distributed algorithms in a unique way to achieve economically feasible utilization and storage of alternative energy sources in a distributed fashion. The FREEDM microgrid consists of residential

Ravi Akella; Fanjun Meng; Derek Ditch; Bruce McMillin; Mariesa Crow

2010-01-01

219

Power Management and Distribution Trades Studies for a Deep-space Mission Scientific Spacecraft  

NASA Astrophysics Data System (ADS)

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 50 kWe to one-half of the ion thrusters and science modules, but is capable of supplying the total power requirements 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.

Kimnach, Greg L.; Soltis, James V.

2004-02-01

220

Power Management and Distribution Trades Studies for a Deep-Space Mission Scientific Spacecraft  

NASA Technical Reports Server (NTRS)

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.

Kimnach, Greg L.; Soltis, James V.

2004-01-01

221

Effects of voltage unbalance and harmonics on three-phase SPWM AC-to-DC converters with instantaneous power feedback  

Microsoft Academic Search

A PWM three-phase AC-to-DC converter with unity input power factor can be approached by setting the required active power and setting reactive power to zero in the instantaneous reactive power theory. The instantaneous reactive power theory, proposed by Akagi, is usually used to design reactive power and harmonic compensators, and it is based on a balanced three-phase voltage source. But,

Wen-Inne Tsai; Ming-Tsung Tsai; York-Yih Sun

1993-01-01

222

Issues and status of power distribution options for space exploration  

NASA Technical Reports Server (NTRS)

The Space Exploration Initiative (SEI) will need a wide variety of manned systems with requirements significantly different than those for existing systems. The concept of a space power utility is discussed and the impact of this concept on the engineering of space power systems is examined. Almost all existing space power systems use low voltage direct current. Although they have been very succesful, increasing power system requirements in recent years have exposed their inherent limitations and led to the proposal of a number of alternatives including high voltage DC and AC at various frequencies. Drawing on the experience gained from Space Station Freedom and SEI systems studies, factors that may affect the choice of frequency standards on which to build such a space power utility are discussed.

Bercaw, Robert W.; Cull, Ronald C.; Kenny, Barbara H.

1991-01-01

223

Development of a Niobium-copper-invar composite conductor for an AC superconducting power transmission cable  

Microsoft Academic Search

A superconducting ac power cable has been developed using Nb\\/Cu\\/Invar composite conductors and shields in a coaxial configuration with pressurized. He at 4.7 K as the primary dielectric. Two major concerns for this cable system were the accommodation of fault currents and the differential thermal expansion between the conductor assembly and the cryogenic envelope. We have shown that a Nb\\/Cu\\/Invar

1975-01-01

224

Single chip controller for a high-switching frequency DC\\/AC power inverter  

Microsoft Academic Search

The design and implementation of a new controller for a DC\\/AC power inverter is described. The controller uses the high switching frequency sinusoidal PWM technique and achieves excellent output voltage regulation, frequency stability and dynamic response in a noiseless, light-weight and cost-effective construction. The inverter performance is analysed using experimental results as well as the harmonic analysis based on the

T. ANTONAKOPOULOS; S. PRESSAS; V. MAKIOS

1992-01-01

225

Silicon carbide power semiconductor module development for a high temperature 10 kW AC drive  

Microsoft Academic Search

A silicon carbide power module has been developed to demonstrate a high-temperature, 10 kW AC drive application. Several goals for this development include temperature dependent parameter evaluation of parallel-connected transistors and junction barrier Schottky diodes at 150 °C operating temperature. Next, design of a high-thermal conductivity substrate to cool the modules based on predicted losses. Finally the integration into a

Dimosthenis Katsis; Bruce Geil; Timothy Griffin; Gail Koebke; Steven Kaplan; Gregory Ovrebo; Stephen Bayne

2005-01-01

226

Comparative Performance of Isolated Forward and Flyback AC-DC Converters for Low Power Applications  

Microsoft Academic Search

This paper addresses several issues concerning the modeling and application of single-phase, single switch, power factor corrected AC-DC high frequency switching converter topologies with transformer isolation. A detailed analysis, simulation and development are presented for forward buck and flyback buck-boost converters with high frequency isolation in discontinuous conduction mode (DCM) operation. To verify and investigate the design and performance at

B. Singh; G. D. Chaturvedi

2008-01-01

227

Smart grid initiative for power distribution utility in India  

Microsoft Academic Search

After enactment of Electricity Act '2003 in India, a comprehensive change is happening in Indian power sector, and power distribution utilities are going through a reformation process to cope up with the regulatory change for reduction in Aggregated Technical and Commercial Loss, improvement in Power Quality, Reliability of Power Supply, Improvement in Customer Satisfaction and rationalization of electricity tariff. Apart

Arup Sinha; S. Neogi; R. N. Lahiri; S. P. Chowdhury; N. Chakraborty

2011-01-01

228

Controlling Solar-Power Systems With Distributed Processors  

NASA Technical Reports Server (NTRS)

System undergoing development uses distributed microprocessors to monitor and control photovoltaic power system. Equipment increases life expectancy and reliability of power system and decreases costs. Adapted to vehicular, residential, and commercial solar and nonsolar power systems. Equipment especially desirable in systems with overall power levels above few kilowatts.

Imamura, M. S.; Moser, R. L.

1985-01-01

229

Environment Design of Power Distribution Facilities. Measurement of Scenic Effects.  

National Technical Information Service (NTIS)

In order to estimate quantitatively the effects of an environment design such as undergrounding of distribution poles or wires for power distribution facilities on the creation of pleasant pedestrian spaces, the development of a effect measurement method ...

K. Yamamoto Y. Yamashita Y. Wakatani

1988-01-01

230

Technology spin-off from space power automation to terrestrial electrical power distribution control and operation  

Microsoft Academic Search

Areas which hold potential for technology spin-off from space power automation into terrestrial electrical power distribution control and automation are investigated. Areas touched upon include load management, loss reduction, trend analysis, energy storage, and fault diagnosis and analysis with expert systems. A brief overview of terrestrial electric power technology and automation in terrestrial distribution is provided. Power handling capabilities, hardware,

C. T. Callis; R. P. Broadwater; A. Chandrasekaran

1987-01-01

231

Spectral and Power Stability Tests of Deep UV LEDs for AC Charge Management  

NASA Astrophysics Data System (ADS)

Deep ultraviolet (UV) LEDs have recently been used in AC charge management experiments to support gravitational reference sensors for future space missions. The UV LED based charge management system offers compact size, light weight, and low power consumption compared to plasma sources. The AC charge management technique, which is enabled by easy modulation of UV LED output, achieves higher dynamic range for charge control. Further, the high modulation frequency, which is out of the gravitational wave detection band, reduces disturbances to the proof mass. However, there is a need to test and possibly improve the lifetime of UV LEDs, which were developed only a year ago. We have initiated a series of spectral and power stability tests for UV LEDs and designed experiments according to the requirements of AC charge management. We operate UV LEDs with a modulated current drive and maintain the operating temperature at 22 °C,28 similar to the LISA spacecraft working condition. The testing procedures involve measuring the baseline spectral shape and output power level prior to the beginning of the tests and then re-measuring the same quantities periodically. As of the date of submission (August 28th, 2006), we have operated a UV LED for more than 2,700 hours.

Sun, Ke-Xun; Higuchi, Sei; Goh, Allex; Allard, Brett; Gill, Dale; Buchman, Saps; Byer, Robert

2006-11-01

232

Hierarchical Power Distribution With Power Tree in Dozens of Power Domains for 90-nm Low-Power Multi-CPU SoCs  

Microsoft Academic Search

Hierarchical power distribution with a power tree has been developed. The key features are a power-tree structure with three power-tree management rules and a distributed common power domain implementation. The hierarchical power distribution supports a fine-grained power gating with dozens of power domains, which is analogous to a fine-grained clock gating. Leakage currents of a 1 000 000-gate power domain

Yusuke Kanno; Hiroyuki Mizuno; Yoshihiko Yasu; Kenji Hirose; Yasuhisa Shimazaki; Tadashi Hoshi; Yujiro Miyairi; Toshifumi Ishii; Tetsuya Yamada; Takahiro Irita; Toshihiro Hattori; Kazumasa Yanagisawa; Naohiko Irie

2007-01-01

233

Measurement of power frequency AC current using FBG and GMM  

Microsoft Academic Search

There is a potential demand for optical current instrument transformer (OCT) in power industry. In the past two decades, R&D on OCT was focused on Faraday effect based technology. As a sensing technology, Fiber Bragg grating (FBG) was more and more attractive recently. For OCT, FBG and giant magnetostrictive material (GMM) based technology will be another choice. In this paper,

Zhao Hong I; Xiong Yanling; Zhang Jian; Wang Shurong

2005-01-01

234

Transformerless topologies for future stationary AC-railway power supply  

Microsoft Academic Search

Railways in several countries in Europe are operated with a 15 kV 16 2\\/3 Hz resp 16,7 Hz. These systems are often supplied from the 50 Hz three-phase system by static frequency converters (SFC). The disadvantages related to the single-phase converter transformer are itemized. Transformerless topologies with corresponding power semiconductors are given and evaluated.

Jens Ranneberg

2007-01-01

235

Electromechanical systems with transient high power response operating from a resonant AC link  

NASA Technical Reports Server (NTRS)

The combination of an inherently robust asynchronous (induction) electrical machine with the rapid control of energy provided by a high frequency resonant AC link enables the efficient management of higher power levels with greater versatility. This could have a variety of applications from launch vehicles to all-electric automobiles. These types of systems utilize a machine which is operated by independent control of both the voltage and frequency. This is made possible by using an indirect field-oriented control method which allows instantaneous torque control in all four operating quadrants. Incorporating the AC link allows the converter in these systems to switch at the zero crossing of every half cycle of the AC waveform. This zero loss switching of the link allows rapid energy variations to be achieved without the usual frequency proportional switching loss. Several field-oriented control systems were developed by LeRC and General Dynamics Space Systems Division under contract to NASA. A description of a single motor, electromechanical actuation system is presented. Then, focus is on a conceptual design for an AC electric vehicle. This design incorporates an induction motor/generator together with a flywheel for peak energy storage. System operation and implications along with the associated circuitry are addressed. Such a system would greatly improve all-electric vehicle ranges over the Federal Urban Driving Cycle (FUD).

Burrows, Linda M.; Hansen, Irving G.

1992-01-01

236

Intelligent distributed control for nuclear power plants  

SciTech Connect

This report discusses the following work: learning systems demo programmed in a bailey MFC; robust fault-accommodating controller design; VAX Cluster <-> UNIX network distributed simulation; programming of schultz's automatic control; distributed diagnostics; and verification and validation.

Klevans, E.H.

1991-01-01

237

Modeling and power quality enhancement to AC drives based on synchronous PI current control technology of PWM rectifier  

Microsoft Academic Search

This paper researches the performance analysis of a power quality enhancement rectifier fed vector control induction motor (VCIM) for electric driving application and presents a power quality enhancement test system to AC drives fed by PWM rectifier using synchronous PI current control technique. The PWM rectifier provides the tested system for research on the power quality of grid. The induction

Chaoyong Guo; Fei Lin; Xiaojie You; Trillion Q. Zheng

2008-01-01

238

Space power management and distribution status and trends  

NASA Technical Reports Server (NTRS)

An overview of space power management and distribution (PMAD) is provided which encompasses historical and current technology trends. The PMAD components discussed include power source control, energy storage control, and load power processing electronic equipment. The status of distribution equipment comprised of rotary joints and power switchgear is evaluated based on power level trends in the public, military, and commercial sectors. Component level technology thrusts, as driven by perceived system level trends, are compared to technology status of piece-parts such as power semiconductors, capacitors, and magnetics to determine critical barriers.

Reppucci, G. M.; Biess, J. J.; Inouye, L.

1984-01-01

239

Resonant AC to AC converter  

Microsoft Academic Search

This paper proposes a novel, power electronics system, a series resonant AC to AC converter, capable of converting a single phase AC supply of frequency fi, into a balanced three-phase supply of frequency foc that may he both higher as well as lower to the input frequency. Use of microcontrollers to control the trigger pulses has made it more versatile.

Vineeta Agarwal; Sachin Nema

2005-01-01

240

Summary of Distributed Resources Impact on Power Delivery Systems  

Microsoft Academic Search

Because traditional electric power distribution systems have been designed assuming the primary substation is the sole source of power and short-circuit capacity, DR interconnection results in operating situations that do not occur in a conventional system. This paper discusses several system issues which may be encountered as DR penetrates into distribution systems. The voltage issues covered are the DR impact

Robert Saint; Roger C. Dugan; Jim Burke; Ljubomir A. Kojovic

2008-01-01

241

The electrical power distribution system for the nonelectrical engineer  

Microsoft Academic Search

An attempt is made to introduce to the nonelectrical engineer the basic components and terminologies associated with a power distribution system and to present the needs such a system requires to remain safe and reliable. Particular reference is made to the power distribution system of a cement plant

Robert A. Haas; M. J. Klova

1991-01-01

242

The Load Forecasting Technology in the Electric Power Distribution System  

Microsoft Academic Search

We proposed the technology which estimates an electric current value at the time each being positive for each power distribution line. Generally, as for the reported demand forecast (for example, are demand forecast by the electricity supply place level and so on), to consider that the load which becomes a base moves isn't necessary. However, as for the power distribution

Tsuneyo Sano; Itsuko Tezuka; Yoshihiro Fukuda

2004-01-01

243

Power distribution\\/allocation in multirate wideband CDMA systems  

Microsoft Academic Search

A unified approach for power distribution and allocation in a multirate wideband CDMA system is investigated. It is shown that the traffic demand and the background disturbance fully govern the feasibility of the system and the optimal power distribution solutions, where the traffic demand is specified by the user QoS requirement, data rate, and spread spectrum bandwidth; the background disturbance

Lian Zhao; Jon W. Mark; Jiu Ding

2006-01-01

244

Interconnection of Distributed Generators and Their Influences on Power System  

Microsoft Academic Search

The increasing penetration of distributed generation (DG) in the power system creates new challenges and problems for network operators. The generation of electricity comes to a new era with a variety of small-scale technologies from conventional generators to sources connected to grids through power electronic converters. The impact of different technologies and installed capacity on a distribution system changes from

Vu Van Thong; Johan Driesen; Ronnie Belmans

245

Communication Using Pseudonoise Modulation on Electric Power Distribution Circuits  

Microsoft Academic Search

Localized communication networks for office automation, security monitoring, environmental management of buildings, computer communications, and other applications enjoy every increasing demand. This paper considers communication of data and analog message signals over electric power distribution circuits for such applications, using pseudonoise (PN) modulation. Advantages of power distribution circuits include reasonably universal coverage and easy access via a standard wall plug.

P. van der Gracht; R. W. Donaldson

1985-01-01

246

A User-Oriented Power Distribution System Analysis Program.  

National Technical Information Service (NTIS)

This paper is a revision of a digital computer program written to perform a load flow and/or short circuit analysis of a power distribution system. The program has been named Power Distribution System Analysis Program (PDSAP). The program capacity is 250 ...

J. A. Underwood

1976-01-01

247

Investigation of Power Processing Technology for Spacecraft Applications.  

National Technical Information Service (NTIS)

This report summarizes an investigation of power processing technology applicable to future satellite electrical power systems. The issues of AC vs DC distribution are addressed as is the optimum distribution voltage. DC distribution is recommended. Distr...

A. S. Gilmour

1982-01-01

248

Input/output harmonic free current link three-phase AC power supply  

NASA Astrophysics Data System (ADS)

The three-phase current link AC to AC power supply, a relatively new topology for AC power supply application, has several potential advantages such as smaller number of magnetic components, lower switching frequency and more rugged operation. Despite this, it has received very little attention by the researchers, and the majority of work found in the literature is confined to the application of voltage type converters in this area. This thesis presents a comprehensive systematic approach for steady state/dynamic analysis and design of three-phase current link AC to AC power supplies. Concept of PWM methods in three-phase current type converters (CTC) is explained and the associated constraints in PWM pattern generation are addressed. Several PWM techniques are described and their performance from different aspects are compared. A steady state analysis is presented based on the Fourier representation of PWM waveforms which allows an accurate prediction of the relationships between the fundamental/harmonic components of the waveforms and other system parameters. Expressions governing various steady state characteristics of the system are derived. A dynamic model using the concept of local average of signals is established. The agreement between the dynamic behavior of switching system and derived model is illustrated. Phenomenon of multiple crossing is explained and the necessary requirement for avoiding such a phenomenon is obtained. The concept of internal model controllers is introduced and its application in the inverter control system for achieving zero steady state error is described. A detailed design procedure is presented. Root-locus method is used to design the system controllers. The applicability of different models in different design problems is discussed. All s-domain designs are verified by time-domain simulations. Experiments are conducted on a 2 KVA, 60 Hz to 50 Hz power supply. A 32 bit DSP-base high performance controller is used to implement the control system. The predicted steady state and dynamic results as well as the time-domain simulations are experimentally verified.

Karshenas, Hamid Reza

249

The 39th annual power distribution conference  

SciTech Connect

This book contains 14 selections. Some of the titles are: Public Utility Commissions and Regulations; Dual Feed with Static Transfer Switching as an Alternative to an Uninterruptible Power Supply; Dallas Power and Light Service Control and Dispatch Center; and Transformer Failure Rate Factors.

Not Available

1987-01-01

250

Distributed Simulation Applied to Shipboard Power Systems  

Microsoft Academic Search

The development of shipboard power systems for the new generation of all-electric ships is challenging in two aspects. First, all new equipment needs to be tested before being installed onboard; otherwise, the design and testing process would become increasingly costly and risky. Second, the complexity of a shipboard power system demands the use of significant computational resources for detailed computer-aided

Qinghua Huang; Jian Wu; Jimena L. Bastos; Noel N. Schulz

2007-01-01

251

Electrical power generation and distribution system  

Microsoft Academic Search

Problems associated with moving fuel from remote sources to large centralized power generation plants are avoided with an economical system for collecting power from small stations located near the scattered, remote fuel sites. To avoid a need for many massive, costly transformers, a plurality of relatively low voltage generating stations are connected in series to cumulatively produce the high voltage

Jeppson

1977-01-01

252

Distribution power flow for smart grid technologies  

Microsoft Academic Search

Smart Grid technologies hold the promise of being able to solve many of the problems currently facing in the electric power industry. However, the large scale deployment of these new technologies has been limited due to an inability to accurately model their effects or to quantify their potential benefits. GridLAB-D is a new open source power system modeling and simulation

Kevin P. Schneider; David P. Chassin; Yousu Chen; Jason C. Fuller

2009-01-01

253

Dynamic Model and Control of AC–DC–AC Voltage-Sourced Converter System for Distributed Resources  

Microsoft Academic Search

This paper introduces a dynamic model of the ac-dc-ac voltage-sourced converter (VSC) system which provides a linear relationship between the input and output variables. The model is developed in two steps. First, the exact abc frame switched model of a VSC is transformed to a switching reference frame (SRF). Then, the SRF model is transformed to an appropriate dq0 reference

H. Nikkhajoei; R. Iravani

2007-01-01

254

Appartus for identifying defective electric power distribution capacitors  

SciTech Connect

An apparatus for determining the operating condition of capacitors of the type used for power factor correction on electric distribution systems is assembled in two sections. A first power supply device supplies an alternating electric current to a de-energized capacitor without removing it from its installed position and a second power measurement device, utilizing either a split-core Hall-device or a special distributed winding, measures the magnitude of the electric current entering the capacitor being tested.

Burkum, M. E.; O'Regan, T. M.

1985-09-10

255

Inverter power module with distributed support for direct substrate cooling  

DOEpatents

Systems and/or methods are provided for an inverter power module with distributed support for direct substrate cooling. An inverter module comprises a power electronic substrate. A first support frame is adapted to house the power electronic substrate and has a first region adapted to allow direct cooling of the power electronic substrate. A gasket is interposed between the power electronic substrate and the first support frame. The gasket is configured to provide a seal between the first region and the power electronic substrate. A second support frame is adapted to house the power electronic substrate and joined to the first support frame to form the seal.

Miller, David Harold (San Pedro, CA); Korich, Mark D. (Chino Hills, CA); Ward, Terence G. (Redondo Beach, CA); Mann, Brooks S. (Redondo Beach, CA)

2012-08-21

256

Automation of Space Station module power management and distribution system  

NASA Technical Reports Server (NTRS)

Viewgraphs on automation of space station module (SSM) power management and distribution (PMAD) system are presented. Topics covered include: reasons for power system automation; SSM/PMAD approach to automation; SSM/PMAD test bed; SSM/PMAD topology; functional partitioning; SSM/PMAD control; rack level autonomy; FRAMES AI system; and future technology needs for power system automation.

Bechtel, Robert; Weeks, Dave; Walls, Bryan

1990-01-01

257

Benefits of Power Electronic Interfaces for Distributed Energy Systems  

Microsoft Academic Search

With the increasing use of distributed energy (DE) systems in industry and its technological advancement, it is becoming more important to understand the integration of these systems with the electric power systems. New markets and benefits for DE applications include the ability to provide ancillary services, improve energy efficiency, enhance power system reliability, and allow customer choice. Advanced power electronic

Benjamin Kroposki; Christopher Pink; Richard DeBlasio; Holly Thomas; Marcelo Simões; Pankaj K. Sen

2010-01-01

258

Accelerated electromechanical dynamic modelling of a distributed generation power pack  

Microsoft Academic Search

Distributed diesel generation is widely used to supply electric power in a variety of applications. These applications range from backup power supply systems and combined wind- diesel generation to providing power in places where grid connection is either technically impractical or financially uneconomic. Modelling and optimisation of such systems as a whole is extremely difficult due to the long-time load

C. I. Hill; P. Zanchetta; S. V. Bozhko

2011-01-01

259

Load Frequency Control in Power System with Distributed Generation  

Microsoft Academic Search

This paper proposes a method to improve the load frequency control in a power system with distributed generation (DG). DG is assumed to include photovoltaic generation, wind power generation, fuel cells and etc. In this paper, a simulation is performed using a microgrid model or island model that is composed of a storage system with either wind power generation or

Kazuto Yukita; Takuya Ota; Koji Fujimoto; Yasuyuki Goto; Katuhiro Ichiyanagi

2010-01-01

260

Distributed Generation: towards an effective contribution to power system security  

Microsoft Academic Search

With a continuously increasing penetration in power system, the impact of dispersed generation is getting higher and higher. This paper deals with the contribution of DG to power system security. It focuses more precisely on its behavior in case of severe frequency disturbances and shows how distributed generation can provide an active contribution to power system security. The UCTE represents

B. Meyer

2007-01-01

261

Local control of reactive power by distributed photovoltaic generators  

SciTech Connect

High penetration levels of distributed photovoltaic (PV) generation on an electrical distribution circuit may severely degrade power quality due to voltage sags and swells caused by rapidly varying PV generation during cloud transients coupled with the slow response of existing utility compensation and regulation equipment. Although not permitted under current standards for interconnection of distributed generation, fast-reacting, VAR-capable PV inverters may provide the necessary reactive power injection or consumption to maintain voltage regulation under difficult transient conditions. As side benefit, the control of reactive power injection at each PV inverter provides an opportunity and a new tool for distribution utilities to optimize the performance of distribution circuits, e.g. by minimizing thermal losses. We suggest a local control scheme that dispatches reactive power from each PV inverter based on local instantaneous measurements of the real and reactive components of the consumed power and the real power generated by the PVs. Using one adjustable parameter per circuit, we balance the requirements on power quality and desire to minimize thermal losses. Numerical analysis of two exemplary systems, with comparable total PV generation albeit a different spatial distribution, show how to adjust the optimization parameter depending on the goal. Overall, this local scheme shows excellent performance; it's capable of guaranteeing acceptable power quality and achieving significant saving in thermal losses in various situations even when the renewable generation in excess of the circuit own load, i.e. feeding power back to the higher-level system.

Chertkov, Michael [Los Alamos National Laboratory; Turitsyn, Konstantin [Los Alamos National Laboratory; Sulc, Petr [Los Alamos National Laboratory; Backhaus, Scott [Los Alamos National Laboratory

2010-01-01

262

Firm Market Power and the Earnings Distribution.  

National Technical Information Service (NTIS)

Using the Longitudinal Employer Household Dynamics (LEHD) data from the United States Census Bureau, I compute firm-level measures of labor market (monopsony) power. To generate these measures, I extend the dynamic model proposed by Manning (2003) and est...

D. A. Webber

2011-01-01

263

Decentralised Electrical Distribution Network in Power Plants.  

National Technical Information Service (NTIS)

A centralized network is the most common network solution in today's power plants. In this study a centralized and a decentralized network were designed in order to compare them economically and technically. The network of the Kirkniemi (Lohja, Finland) p...

P. Mannila M. Lehtonen

2000-01-01

264

Distribution Power Flow for Smart Grid Technologies  

SciTech Connect

Smart Grid technologies hold the promise of being able to solve many of the problems currently facing in the electric power industry. However, the large scale deployment of these new technologies has been limited due to an inability to accurately model their effects or to quantify their potential benefits. GridLAB-D is a new open source power system modeling and simulation environment developed by the United States Department of Energy specifically to integrate detailed power systems and end-use models. In order to effectively model the vast array of possible smart grid technologies GridLAB-D was developed as a general simulation environment. This paper describes the basic design concept, the power flow solutions implemented, and a detailed example of the type of analysis that can be performed within the simulation environment in order to support the evaluation of smart grid technologies.

Schneider, Kevin P.; Chassin, David P.; Chen, Yousu; Fuller, Jason C.

2009-03-18

265

Power System Information Delivering System Based on Distributed Object  

NASA Astrophysics Data System (ADS)

In recent years, improvement in computer performance and development of computer network technology or the distributed information processing technology has a remarkable thing. Moreover, the deregulation is starting and will be spreading in the electric power industry in Japan. Consequently, power suppliers are required to supply low cost power with high quality services to customers. Corresponding to these movements the authors have been proposed SCOPE (System Configuration Of PowEr control system) architecture for distributed EMS/SCADA (Energy Management Systems / Supervisory Control and Data Acquisition) system based on distributed object technology, which offers the flexibility and expandability adapting those movements. In this paper, the authors introduce a prototype of the power system information delivering system, which was developed based on SCOPE architecture. This paper describes the architecture and the evaluation results of this prototype system. The power system information delivering system supplies useful power systems information such as electric power failures to the customers using Internet and distributed object technology. This system is new type of SCADA system which monitors failure of power transmission system and power distribution system with geographic information integrated way.

Tanaka, Tatsuji; Tsuchiya, Takehiko; Tamura, Setsuo; Seki, Tomomichi; Kubota, Kenji

266

Power flow study and voltage stability analysis for distribution systems with distributed generation  

Microsoft Academic Search

The voltage instability phenomena may occur in distribution networks. The decline of voltage stability level will restrict the increase of load served by distribution companies. Distributed generation (DG) is increasingly drawing great attention of people. The development of DGs will bring new chances to traditional power systems. DGs connected to distribution networks are potential to improve the system voltage stability.

Haiyan Chen; Jinfu Chen; Dongyuan Shi; Xianzhong Duan

2006-01-01

267

Determining the impact of distributed generation on power systems. I. Radial distribution systems  

Microsoft Academic Search

Distributed generation (DG) has much potential to improve distribution system performance and it should be encouraged. However, distribution system designs and operating practices are normally based on radial power flows and this creates a special challenge to the successful introduction of distributed generation. This paper has described a few of the issues that must be considered to insure that DG

Philip P. Barker; Robert W. de Mello

2000-01-01

268

An 18Pulse AC-DC Converter for Power Quality Improvement in Vector Controlled Induction Motor Drives  

Microsoft Academic Search

This paper deals with a novel autotransformer based improved power quality eighteen-pulse ac-dc converter feeding vector controlled induction motor drives (VCIMD's). The design of the proposed autotransformer is presented along with the necessary modifications required for making it suitable for retrofit applications, where presently a 6-pulse diode bridge rectifier is used. The proposed ac-dc converter is found capable of improving

Bhim Singh; G. Bhuvaneswari; Vipin Garg

2006-01-01

269

Power-quality improvements in vector-controlled induction motor drive employing pulse multiplication in AC-DC converters  

Microsoft Academic Search

This paper deals with the pulse doubling in a 12-pulse ac-dc converter for improving power quality in vector-controlled induction motor drives (VCIMDs). The design of proposed magnetics shows the flexibility in varying the voltage ratio of the autotransformer for making it suitable for retrofit applications, where presently a six-pulse diode bridge rectifier is being used. The proposed ac-dc converter is

Bhim Singh; G. Bhuvaneswari; Vipin Garg

2006-01-01

270

A Novel T-Connected Autotransformer Based 30- Pulse AC-DC Converter for Power Quality Improvement  

Microsoft Academic Search

This paper presents the design and analysis of a novel T-connected autotransformer based 30-phase ac-dc converter which supplies direct torque controlled induction motor drives (DTCIMD's) in order to have better power quality conditions at the point of common coupling. The proposed converter output voltage is accomplished via three paralleled 10-pulse ac-dc converters each of them consisting of 5-phase diode bridge

Rohollah Abdollahi

2012-01-01

271

The Application of Active Superconducting DC Fault Current Limiter in Hybrid AC\\/DC Power Supply Systems  

Microsoft Academic Search

This paper presents a new topology of the active superconducting DC fault current limiter (DC-SFCL) applied in the hybrid AC\\/DC power supply systems. The proposed DC-SFCL is composed of superconducting transformer, DC chopper and voltage source converter (VSC). The primary winding of the transformer is connected in series with DC transmission line, and the second winding is connected with AC

Jing Shi; Yuejin Tang; Lei Chen; Jin Wang; Li Ren; Jingdong Li; Liang Li; Tao Peng; Shijie Cheng

2008-01-01

272

Reliable, Efficient and Cost-Effective Electric Power Converter for Small Wind Turbines Based on AC-link Technology  

Microsoft Academic Search

Grid-tied inverter power electronics have been an Achilles heel of the small wind industry, providing opportunity for new technologies to provide lower costs, greater efficiency, and improved reliability. The small wind turbine market is also moving towards the 50-100kW size range. The unique AC-link power conversion technology provides efficiency, reliability, and power quality advantages over existing technologies, and Princeton Power

Darren Hammell; Mark Holveck; DOE Project Officer

2006-01-01

273

Statistical Analyses Support Power Law Distributions Found in Neuronal Avalanches  

PubMed Central

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.

Klaus, Andreas; Yu, Shan; Plenz, Dietmar

2011-01-01

274

An Analysis of Sub Sea Electric Power Transmission Techniques from DC to AC 50\\/60 Hz and Beyond  

Microsoft Academic Search

In the past decade, the significant improvements in high speed, high voltage transistor technology enabled the design of more sophisticated sub sea electrical power transmission systems. This is the case of the power-electronics-based single wire DC and high frequency AC transmission systems that appeared as alternatives to the traditional three phase transmission systems. Although such advanced alternatives have been employed

Michael C. Wrinch; M. A. Tomim; J. Marti

2007-01-01

275

Power balance control techniques applied to parallel AC to DC converters using single-phase SEPIC rectifier modules  

Microsoft Academic Search

Power balance control techniques applied to parallel AC to DC converters for single-phase SEPIC rectifier modules is presented. The analysis and simulation results of such system with nearly unity power factor using single voltage loop control and inductor current calculator for input current wave shaping and output voltage regulation have been shown. Each converter operates in continuous conduction mode and

U. Kamnarn; V. Chunkag

2004-01-01

276

Lowest of AC-DC power output for electrostrictive polymers energy harvesting systems  

NASA Astrophysics Data System (ADS)

Advances in technology led to the development of electronic circuits and sensors with extremely low electricity consumption. At the same time, structural health monitoring, technology and intelligent integrated systems created a need for wireless sensors in hard to reach places in aerospace vehicles and large civil engineering structures. Powering sensors with energy harvesters eliminates the need to replace batteries on a regular basis. Scientists have been forced to search for new power source that are able to harvested energy from their surrounding environment (sunlight, temperature gradients etc.). Electrostrictive polymer belonging to the family of electro-active polymers, offer unique properties for the electromechanical transducer technology has been of particular interest over the last few years in order to replace conventional techniques such as those based on piezoelectric or electromagnetic, these materials are highly attractive for their low-density, with large strain capability that can be as high as two orders of magnitude greater than the striction-limited, rigid and fragile electroactive ceramics. Electrostrictive polymers sensors respond to vibration with an ac output signal, one of the most important objectives of the electronic interface is to realize the required AC-DC conversion. The goal of this paper is to design an active, high efficiency power doubler converter for electrostrictive polymers exclusively uses a fraction of the harvested energy to supply its active devices. The simulation results show that it is possible to obtain a maximum efficiency of the AC-DC converter equal to 80%. Premiliminary experimental measurements were performed and the results obtained are in good agreement with simulations.

Meddad, Mounir; Eddiai, Adil; Hajjaji, Abdelowahed; Guyomar, Daniel; Belkhiat, Saad; Boughaleb, Yahia; Chérif, Aida

2013-11-01

277

Power quality improvement of unbalanced power system with distributed generation units  

Microsoft Academic Search

This paper presents a power electronic system for improving the power quality of the unbalanced distributed generation units in three-phase four-wire system. In the system, small renewable power generation units, such as small PV generator, small wind turbines may be configured as single phase generation units. The random nature of renewable power sources may result in significant unbalance in the

Y Hu; Z Chen; P Excell

2011-01-01

278

Monocyclic power: a novel but short-lived power distribution system  

Microsoft Academic Search

This paper provides a brief history of the monocyclic power system, which was rendered obsolete because of its technical complexity and by the development of the three-phase power distribution system. Primarily developed for the General Electric Company as a means of avoiding possible infringement of the Tesla patents, the monocyclic power system was decidedly inferior to the power transmission efficiency

T. Blalock

2005-01-01

279

A MultiFunctional Power Electronic Converter in Distributed Generation Power Systems  

Microsoft Academic Search

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

Z. Chen; F. Blaabjerg; J. K. Pedersen

2005-01-01

280

An intelligent, fault tolerant, high power, distributed power system for massively parallel processing computers  

Microsoft Academic Search

An intelligent, high power distributed power system used in a massively parallel processing (MPP) computer is described. The 7.5 kW power system has high availability, redundancy, fault tolerance, battery back-up, and a user friendly graphical user interface (GUI). A diagnostic subsystem monitors and tests the operation of the power system to ensure the functionality of the redundant assemblies

J. Burns; J. Riel; A. DiBene

1994-01-01

281

Distributed Constraint Optimization Applications in Power Networks  

Microsoft Academic Search

In recent years the electricity sector has undergone a number of changes that all point in the direction of liberalization and decentralization of control. However, a number of technological challenges have to be addressed before the desired degree of de- centralization is obtained. Currently, most of the decisions about the operation of a power system are still made in control

Adrian Petcu; Boi Faltings

2008-01-01

282

Current control of distributed generation power inverters for losses reduction in the distribution network  

Microsoft Academic Search

The main objective of the paper is to evaluate the power losses reduction that can be achieved in a low voltage distribution network when the inverters associated to the distributed generation are used as active power filters to compensate the non active currents produced by inductive and unbalanced loads. For that purpose, a hysteresis current control has been proposed and

E. Belenguer; H. Beltran; N. Aparicio; E. Pérez

283

Distributed Power Sources for Mars Colonization  

NASA Astrophysics Data System (ADS)

One of the fundamental needs for Mars colonization is an abundant source of energy. The total energy system will probably use a mixture of sources based on solar energy, fuel cells, and nuclear energy. Here we concentrate on the possibility of developing a distributed system employing several unique new types of nuclear energy sources, specifically small fusion devices using inertial electrostatic confinement and portable ``battery type'' proton reaction cells.

Miley, George H.; Shaban, Yasser

2003-01-01

284

Shuttle Electrical Power Analysis Program (Sepap) Distribution Circuit Analysis Report.  

National Technical Information Service (NTIS)

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. (Author)

E. M. Torina

1975-01-01

285

Electrical Power Distribution and Control Modeling and Analysis.  

National Technical Information Service (NTIS)

This slide presentation reviews the use of Electrical Power Distribution and Control (EPD&C) Modeling and how modeling can support analysis. The presentation discusses using the EASY5 model to simulate and analyze the Space Shuttle Electric Auxiliary Powe...

I. S. Mehdi J. S. Fu M. Liffring

2001-01-01

286

Space Station Freedom power management and distribution system design  

NASA Technical Reports Server (NTRS)

The design is described of the Space Station Freedom Power Management and Distribution (PMAD) System. In addition, the significant trade studies which were conducted are described, which led to the current PMAD system configuration.

Teren, Fred

1989-01-01

287

Feeder automation for an electric power distribution system  

US Patent & Trademark Office Database

A soft PLC technology based computer-implemented method includes updating a system configuration incidence matrix for an electric power distribution system based on both a depth-first search of a connectivity matrix for the electric power distribution system and information about the electric power distribution system, wherein the information includes at least status information about one or more switches of the electric power distribution system. The method further includes detecting a fault in the system based on the incidence matrix. The method further includes generating isolation control logic based on the incidence matrix and isolating the fault based on isolation control logic. The method further includes generating restoration control logic based on a breadth-first search of the incidence matrix and restoring the system based on the restoration control logic.

2012-02-21

288

Industry Sector Analysis Mexico: Electric Power Production and Distribution Equipment.  

National Technical Information Service (NTIS)

The Industry Sector Analyses (I.S.A.) for electric power production and distribution equipment contains statistical and narrative information on projected market demand, end-users, receptivity of Mexican consumers to U.S. products, the competitive situati...

J. S. Wood R. W. Miller

1988-01-01

289

Shuttle Electrical Power Analysis Program (SEPAP) distribution circuit analysis report  

NASA Technical Reports Server (NTRS)

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.

Torina, E. M.

1975-01-01

290

Interference Mitigation Studies for Texas Telephone and Power Distribution Systems.  

National Technical Information Service (NTIS)

The document demonstrates the effects of various parameters associated with a Sanguine System on the interference mitigation of Texas Telephone and Power Distribution Systems. Cost models are presented, which were developed from this parametric study, for...

J. D. Huber M. F. Genge

1973-01-01

291

Independent Orbiter Assessment (IOA): Analysis of the electrical power distribution and control subsystem, volume 1  

NASA Technical Reports Server (NTRS)

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Electrical Power Distribution and Control (EPD and C) hardware. The EPD and C hardware performs the functions of distributing, sensing, and controlling 28 volt DC power and of inverting, distributing, sensing, and controlling 117 volt 400 Hz AC power to all Orbiter subsystems from the three fuel cells in the Electrical Power Generation (EPG) subsystem. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Of the 1671 failure modes analyzed, 9 single failures were determined to result in loss of crew or vehicle. Three single failures unique to intact abort were determined to result in possible loss of the crew or vehicle. A possible loss of mission could result if any of 136 single failures occurred. Six of the criticality 1/1 failures are in two rotary and two pushbutton switches that control External Tank and Solid Rocket Booster separation. The other 6 criticality 1/1 failures are fuses, one each per Aft Power Control Assembly (APCA) 4, 5, and 6 and one each per Forward Power Control Assembly (FPCA) 1, 2, and 3, that supply power to certain Main Propulsion System (MPS) valves and Forward Reaction Control System (RCS) circuits.

Schmeckpeper, K. R.

1987-01-01

292

Do wealth distributions follow power laws? Evidence from ‘rich lists’  

NASA Astrophysics Data System (ADS)

We use data on the wealth of the richest persons taken from the ‘rich lists’ provided by business magazines like Forbes to verify if the upper tails of wealth distributions follow, as often claimed, a power-law behaviour. The data sets used cover the world’s richest persons over 1996-2012, the richest Americans over 1988-2012, the richest Chinese over 2006-2012, and the richest Russians over 2004-2011. Using a recently introduced comprehensive empirical methodology for detecting power laws, which allows for testing the goodness of fit as well as for comparing the power-law model with rival distributions, we find that a power-law model is consistent with data only in 35% of the analysed data sets. Moreover, even if wealth data are consistent with the power-law model, they are usually also consistent with some rivals like the log-normal or stretched exponential distributions.

Brzezinski, Michal

2014-07-01

293

An AC motor drive with power factor control for low cost applications  

NASA Astrophysics Data System (ADS)

The front-end rectifier followed by a pulse-width modulated voltage source inverter (PWM-VSI) has been a well-established power converter configuration for many industrial drives. The increasing costs on the utility usage, due to power quality regulations, and the need to improve the VA capacity of systems, e.g. off-shore drilling rigs, have increased the interest in the development of power electronic equipment with power factor control capability. Electrical motors consume a large amount of the available electrical energy, and this energy tends to increase due to the massive emerging applications of electrical motor drives in appliances and in industrial processes. Therefore, the improvement of the power factor of these low power drive systems, usually in the range from fractional horse-power (hp) to 1 hp, is of particular interest. For these power ratings, the system configuration usually comprises a single-phase to three-phase type of converter with additional circuitry for power factor control (PFC). However, this approach has an impact on the system cost and packaging. In this work, a new concept of integrating motor and power factor controls by using a single-phase to three-phase DSP based six-switch converter topology is presented. Unlike other configurations using extra switch(es) and/or extra boost inductor, in this circuit the boost action, for input current shaping, is done by the motor leakage inductances. The power factor control and inverter operation are performed by applying two modulating signals to the SPWM control logic of the converter. In this dissertation, the converter operation and a proposed control strategy will be explained. Simulation and experimental results for a DSP based induction motor drive will be provided as proof of concept. The feasibility and potential of this configuration for ac motor drive applications will be established. The impact of this scheme on the machine operation will also be discussed.

Bellar, Maria Dias

2000-10-01

294

Analysis of a novel stator winding structure minimizing harmonic current and torque ripple for dual six-step converter-fed high power AC machines  

Microsoft Academic Search

Many attempts have been made to expand the application of AC motor drives to high-power levels. One way to use AC motor drives at high-power levels is to use multiple power converters together to supply power to a large machine. For a multiple converter combination scheme, the six-step power converter is competitive due to its robust structure and simplicity of

Longya Xu; Lurong Ye

1995-01-01

295

An Effective Approach for Distribution System Power Flow Solution  

Microsoft Academic Search

An effective approach for unbalanced three-phase distribution power flow solutions is proposed in this paper. The special topological characteristics of distribution networks have been fully utilized to make the direct solution possible. Two matrices—the bus-injection to branch-current matrix and the branch-current to bus- voltage matrix— and a simple matrix multiplication are used to obtain power flow solutions. Due to the

A. Alsaadi; B. Gholami

2009-01-01

296

Spatially cascaded cavities for power saving distributed Raman amplification  

NASA Astrophysics Data System (ADS)

A novel distributed amplification scheme with cascaded (using distributed in-line cavities formed by notch filters based on fiber Bragg gratings) ultra-long Raman fiber lasers for transmission with suppressed noise and reduced pump power consumption is proposed and evaluated. Comprehensive numerical analysis shows the possibility of pump power reduction by 50% compared to similar scheme without notch filters while supporting acceptable optical signal-to-noise ratio over large transmission span.

Bednyakova, A. E.; Fedoruk, M. P.

2013-03-01

297

Power law distributions of seismic rates  

NASA Astrophysics Data System (ADS)

We report an empirical determination of the probability density functions Pdata( r) of the number r of earthquakes in finite space-time windows for the California catalog for different space (5 × 5 to 50 × 50 km 2) and time intervals (0.1 to 1000 days). The data can be represented by asymptotic power law tails together with several cross-overs reasonably explained by one of the most used reference model in seismology (ETAS), which assumes that each earthquake can trigger other earthquakes according to complex cascades. These results are useful to constrain the physics of earthquakes and to estimate the performance of forecasting models of seismicity.

Saichev, A.; Sornette, D.

2007-02-01

298

Main Power Distribution Unit for the Jupiter Icy Moons Orbiter (JIMO)  

NASA Technical Reports Server (NTRS)

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 components may interfere with one another. By working with the electrical engineer who is designing the circuit, the specific design requirements for the MPDU were determined and used as guidelines. Space is limited due to the size of the mounting plate therefore each component must be strategically placed. Since the MPDU is being designed to fit into a simulated model of the spacecraft systems on the JIMO, components must be positioned where they are easily accessible to be wired to the other onboard systems. Mechanical and electrical requirements provided equally important limits which are combined to produce the best possible design of the MPDU.

Papa, Melissa R.

2004-01-01

299

A study of power conditioning and power distribution and components  

NASA Technical Reports Server (NTRS)

A comprehensive simulation and analysis performed on the operation of the regulator part of the Charger/Battery/Regulator Module (CBRM) are detailed. The CBRM is utilized as an integral component of the Skylab/Apollo Telescope Mount (ATM) electrical power system and contains a switching mode electronic regulator. Implementing circuit analysis techniques, pertinent voltages and currents are calculated; these, in turn, are incorporated into the regulator system study. Investigation of the turn-on and turn-off times associated with the switching circuitry is performed and an examination is made on these calculations. A simulation model computer program is utilized to generate graphs that relate various CBRM parameters to one another.

Horton, H. M.; Honnell, M. A.

1973-01-01

300

Investigating the Electric Power Distribution System (EPDS) Bus Voltage in the Presence of Distributed Generation (DG)  

Microsoft Academic Search

This paper investigates the Electric Power Distribution System (EPDS) bus voltage in the presence of Distributed Generation (DG). Distribution Company's (Discos) planner endeavor to develop new planning strategies for their network in order to serve the load growth and provide their customers with a reliable electric supply. In this research work, five different cases including preplanned islanding and grid-connected mode

Hasham Khan; Mohammad Ahmad Choudhry; Tahir Mahmood; Aamir Hanif

2006-01-01

301

Double power laws in income and wealth distributions  

NASA Astrophysics Data System (ADS)

Close examination of wealth distributions reveal the existence of two distinct power law regimes. The Pareto exponents of the super-rich, identified, for example in rich lists such as provided by Forbes, are smaller than the Pareto exponents obtained for top earners in income data sets. Our extension of the Slanina model of wealth is able to reproduce these double power law features.

Coelho, Ricardo; Richmond, Peter; Barry, Joseph; Hutzler, Stefan

2008-06-01

302

Optimal investment of distributed generation in restructured power system  

Microsoft Academic Search

The main impacts of DG is to enhance system reliability as it can restore power to the separated part of distribution system in case of a contingency occurs and reduce the overall system operating cost. If the DG operating cost is less than the utility power cost at each hour, DG could be employ to reduce the overall system operating

M. M. Madarshahian; S. Afsharnia; M. S. Ghazizadeh

2009-01-01

303

Electrical power distribution system operating experience review for fusion applications  

Microsoft Academic Search

This paper describes safety research on electrical distribution systems applicable to fusion facilities. Electrical power has many uses in both magnetic and inertial fusion experiments; it is the most important support system for any fusion experiment. Electricity powers a wide variety of plant equipment, including vacuum pumps, magnets, coolant pumps, air handlers, compressors, and either plasma heating or target implosion

L. C Cadwallader

2002-01-01

304

Optimal preventive maintenance budget setting for electric power distribution utilities  

Microsoft Academic Search

This paper proposes a practical method of preventive maintenance budget setting for electric power distribution utilities. Power system reliability mainly depends on preventive maintenance programs including types and frequency of selected maintenance activities controlled by maintenance budgets. In this paper, particle swarm optimization (PSO) is used to find the optimal budget settings in order to minimize the outage costs of

N. Phoothong; P. Vanittanakom; N. Teera-achariyakul; D. Rerkpreedapong

2008-01-01

305

Optimal reactive power and voltage control for radial distribution system  

Microsoft Academic Search

A new approach to optimal reactive power and voltage control problem in a radial distribution system is proposed in this paper. The optimal control problem is to find a proper dispatch schedule for shunt capacitor banks and on-load tap changer at substation and shunt capacitor banks on feeders such that the power loss is minimized and the voltage profile is

Yutian Liu; Peng Zhang; Xizhao Qiu

2000-01-01

306

Faulted Branch Identification on Power Distribution Systems Under Noisy Environment  

Microsoft Academic Search

Faulted branch identification is extremely important for power distribution systems operation and restoration. Also, noisy environments are common in substations, where the relays are normally installed. In this paper a novel formulation that estimates the faulted section of an unbalanced power distribu- tion system considering a noisy environment is presented. The method uses travelling waves and autocorrelation theory, and was

Karen Rezende; Adalberto Shuck Jr; Arturo Suman Bretas

307

Distributed generation: remote power systems with advanced storage technologies  

Microsoft Academic Search

The paper discusses derived from an earlier hypothetical study of remote villiages. It considers the policy implications for communities who have their own local power resources rather than those distributed through transmission from distant sources such as dams, coal power plants or even renewables generation from wind farms, solar thermal or other resources. The issues today, post 911 and the

Woodrow Clark; William Isherwood

2004-01-01

308

Antenna amplitude distributions for improved wireless power transmission efficiency  

Microsoft Academic Search

Here are discussed the methods and algorithms of the amplitude distribution synthesis needed for the increase of the wireless power transmission (WPT) efficiency. It is shown that the WPT efficiency is increased not only of the uniform or the taper distribution but and when the field intensity is raised at the edges of the radiating apertures. In this case the

S. S. Shaposhnikov; R. B. Vaganov; N. N. Voitovich

2002-01-01

309

Automated fault location and diagnosis on electric power distribution feeders  

Microsoft Academic Search

This paper presents new techniques for locating and diagnosing faults on electric power distribution feeders. The proposed fault location and diagnosis scheme is capable of accurately identifying the location of a fault upon its occurrence, based on the integration of information available from disturbance recording devices with knowledge contained in a distribution feeder database. The developed fault location and diagnosis

Jun Zhu; D. L. Lubkeman; A. A. Girgis

1997-01-01

310

Influence of electric power distribution system design on harmonic propagation  

Microsoft Academic Search

The impact of the design parameters of electric power distribution systems on the propagation of harmonic distortion is investigated. This conceptual study is based on simulations on a generalized distribution system model, and leads to an increased insight in the mechanisms of the generation and propagation of voltage distortion. Moreover, analytical expressions are presented that predict the impact of changing

J. A. Ghijselen; W. A. Ryckaert; J. A. Melkebeek

2004-01-01

311

Optimal load shedding strategy in power systems with distributed generation  

Microsoft Academic Search

An optimal load shedding strategy for power systems with multiple distributed generation is presented. According to distributed generation's role in emergency state, they are classified as the central generation type, nondispatchable type and storage type. The dynamic and static models of each type following a major disturbance are developed. Based on the analysis of a major disturbance in a grid

Ding Xu; Adly A. Girgis

2001-01-01

312

Hybrid Filter Applications for Power Quality Improvement of Power Distribution Networks Utilizing Renewable Energies  

Microsoft Academic Search

A hybrid filter constructed of a shunt active filter and distributed passive filters used for power quality improvement in dispersed generation system is presented. The distribution system consists of several kinds of renewable energies as DG units where the power quality problems due to dispersed generation LV systems are introduced and the necessity of using hybrid filters instead of active

G. Ahrabian; F. Shahnia; Mehrdad Tarafdar Haque

2006-01-01

313

Integration of D-Statcom based photovoltaic cell power in low voltage power distribution grid  

Microsoft Academic Search

The main aim of this paper is the voltage regulation which is one of the most important operational requirement in power network at both transmission and distribution levels. Whenever there is a penetration of photovoltaic cell power to the low voltage distributed grid, there occur the problem of mismatch in voltage and frequency in the network, perhaps caused by non

R. Indumathi; M. Venkateshkumar; R. Raghavan

2012-01-01

314

Comparison of two-type corona plasma energization techniques: ultra-short and DC\\/AC power sources  

Microsoft Academic Search

This paper discusses some critical issues when developing industrial corona plasma systems. Based on streamer generation and interaction between power sources and reactors, the power conditions for streamer corona plasma generation can be basically divided into two groups, namely ultra-short and high-frequency oscillation DC\\/AC sources. Today, single- and multiple-switch circuit topologies become available to scale the ultra-short pulsed-power system up.

K. Yan; G. J. J. Winands; Z. Liu; E. J. M. van Heesch; A. J. M. Pemen

2005-01-01

315

Utilization of three-phase thyristor-controlled AC\\/DC converters for reactive power compensation with minimum losses  

Microsoft Academic Search

This paper presents a new control method for three-phase, thyristor-controlled reactors for reactive power compensation applications. A conventional AC\\/DC, three-phase, phase-controlled, bridge power converter is utilized. A relatively small inductance is used for a discontinuous rated inductor current. This results in reducing the inductor size, cost and loss, and greatly reduces the power converter switching losses. Experimental results are shown

D. A. Deib; H. W. Hill

1995-01-01

316

Advanced Electric Distribution, Switching, and Conversion Technology for Power Control  

NASA Technical Reports Server (NTRS)

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.

Soltis, James V.

1998-01-01

317

Hysteresis, phase transitions, and dangerous transients in electrical power distribution systems  

NASA Astrophysics Data System (ADS)

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 the 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 spatiotemporal 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 motors’ mechanical (rotation) frequency is slightly smaller than the nominal frequency of the basic ac flows and a “stalled” state where the mechanical frequency is small. Transitions between the two states can be initiated by a perturbation of the voltage or base frequency at the head of the distribution feeder. Such behavior is typical of first-order phase transitions in physics, and this 1+1 dimensional model shows many other properties of a first-order phase transition with the spatial distribution of the motors’ mechanical frequency playing the role of the order parameter. In particular, we observe (a) propagation of the phase-transition front with the constant speed (in very long feeders) and (b) hysteresis in transitions between the normal and stalled (or partially stalled) phases.

Duclut, Charlie; Backhaus, Scott; Chertkov, Michael

2013-06-01

318

Hysteresis, phase transitions, and dangerous transients in electrical power distribution systems.  

PubMed

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 the 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 spatiotemporal 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 motors' mechanical (rotation) frequency is slightly smaller than the nominal frequency of the basic ac flows and a "stalled" state where the mechanical frequency is small. Transitions between the two states can be initiated by a perturbation of the voltage or base frequency at the head of the distribution feeder. Such behavior is typical of first-order phase transitions in physics, and this 1+1 dimensional model shows many other properties of a first-order phase transition with the spatial distribution of the motors' mechanical frequency playing the role of the order parameter. In particular, we observe (a) propagation of the phase-transition front with the constant speed (in very long feeders) and (b) hysteresis in transitions between the normal and stalled (or partially stalled) phases. PMID:23848724

Duclut, Charlie; Backhaus, Scott; Chertkov, Michael

2013-06-01

319

Distributed generation and centralized power system in Thailand: Conflicts and solutions  

Microsoft Academic Search

Although Thailand has significant potential resources for distributed power generation, the development of renewable distributed generation faces several difficulties. This paper examines and discusses conflicts between the development of distributed power and centralized power system, on both structural issues, especially asymmetric power within the Thai power system, and instrumental issues, such as unfavorable pricing system. Therefore, to support distributed power

Decharut Sukkumnoed

2003-01-01

320

Electrical power distribution control methods, electrical energy demand monitoring methods, and power management devices  

DOEpatents

Electrical power distribution control methods, electrical energy demand monitoring methods, and power management devices are described. In one aspect, an electrical power distribution control method includes providing electrical energy from an electrical power distribution system, applying the electrical energy to a load, providing a plurality of different values for a threshold at a plurality of moments in time and corresponding to an electrical characteristic of the electrical energy, and adjusting an amount of the electrical energy applied to the load responsive to an electrical characteristic of the electrical energy triggering one of the values of the threshold at the respective moment in time.

Chassin, David P. (Pasco, WA); Donnelly, Matthew K. (Kennewick, WA); Dagle, Jeffery E. (Richland, WA)

2006-12-12

321

Electrical power distribution control methods, electrical energy demand monitoring methods, and power management devices  

DOEpatents

Electrical power distribution control methods, electrical energy demand monitoring methods, and power management devices are described. In one aspect, an electrical power distribution control method includes providing electrical energy from an electrical power distribution system, applying the electrical energy to a load, providing a plurality of different values for a threshold at a plurality of moments in time and corresponding to an electrical characteristic of the electrical energy, and adjusting an amount of the electrical energy applied to the load responsive to an electrical characteristic of the electrical energy triggering one of the values of the threshold at the respective moment in time.

Chassin, David P. (Pasco, WA); Donnelly, Matthew K. (Kennewick, WA); Dagle, Jeffery E. (Richland, WA)

2011-12-06

322

Space Station Freedom power management and distribution design status  

NASA Technical Reports Server (NTRS)

The design status of the power management and distribution electric power system for the Space Station Freedom is presented. The current design is a star architecture, which has been found to be the best approach for meeting the requirement to deliver 120 V dc to the user interface. The architecture minimizes mass and power losses while improving element-to-element isolation and system flexibility. The design is partitioned into three elements: energy collection, storage and conversion, system protection and distribution, and management and control.

Javidi, S.; Gholdston, E.; Stroh, P.

1989-01-01

323

Estimation in a fluctuating medium and power-law distributions  

NASA Astrophysics Data System (ADS)

We show how recent results by Bening and Korolev in the context of estimation, when linked with a classical result of Fisher concerning the negative binomial distribution, can be used to explain the ubiquity of power-law probability distributions. Beck, Cohen and others have provided plausible mechanisms explaining how power-law probability distributions naturally emerge in scenarios characterized by either finite dimension or fluctuation effects. This Letter tries to further contribute to such an idea. As an application, a new and multivariate version of the central limit theorem is obtained that provides a convenient alternative to the one recently presented in [S. Umarov, C. Tsallis, S. Steinberg, cond-mat/0603593].

Vignat, C.; Plastino, A.

2007-01-01

324

Power distribution system planning with reliability modeling and optimization  

SciTech Connect

A new approach for the systemized optimization of power distribution systems is presented in this paper. Distribution system reliability is modeled in the optimization objective function via outage costs and costs of switching devices, along with the nonlinear costs of investment, maintenance and energy losses of both the substations and the feeders. The optimization model established is multi-stage, mixed-integer and nonlinear, which is solved by a network-flow programming algorithm. A multi-stage interlacing strategy and a nonlinearity iteration method are also designed. Supported by an extensive database, the planning software tool has been applied to optimize the power distribution system of a developing city.

Tang, Y. [Siemens Power Corp., Roswell, GA (United States)] [Siemens Power Corp., Roswell, GA (United States)

1996-02-01

325

Microwave and ac power absorption and ac susceptibility measurements of the high-Tc superconducting Tl-Ba-Ca-Cu-O system near zero field  

NASA Astrophysics Data System (ADS)

The low-field dependence of electrical power absorption and ac susceptibility-temperature measurements are performed on three ceramic superconductors of the Tl2Ba2CaL-1CuLO4+2L family using modulated and direct microwave and ac methods. Below a critical temperature all samples exhibit a large increase in ac and microwave absorption near zero field, a Meissner effect, and a diamagnetic shielding phenomenon. The microwave signal recorded with a modulation technique has three components, out of which, one with hysteretic character is mostly the product of the normal cores of intragrain fluxons. The observed deviations of the signal from the real absorption behavior are explained. The measured ac susceptibility reflects mainly the moving magnetic flux vortices induced by intergrain Meissner and diamagnetic shielding currents. Our results suggest that the variation of magnetic field induces at low and microwave frequencies the same flux exclusion and penetration processes characterizable macroscopically mostly through the change in diamagnetic surface impedance.

Bódi, A. C.

1990-02-01

326

The Load Forecasting Technology in the Electric Power Distribution System  

NASA Astrophysics Data System (ADS)

We proposed the technology which estimates an electric current value at the time each being positive for each power distribution line. Generally, as for the reported demand forecast (for example, are demand forecast by the electricity supply place level and so on), to consider that the load which becomes a base moves isn’t necessary. However, as for the power distribution system, the change of the composition which is due to the system changing, and so on, and the load curve shape, too, have changed mainly. So, the section of the power distribution line was classified in four kinds of clusters by the composition ratio of every contract classification, and created in the estimate model by the multiple regression analysis. Furthermore, to improve the precision of the estimate model, we calculated an error coefficient of each power distribution line and established the error revision method which distributes an error coefficient to each section. As a result, the absolute average error with estimate electric current value by this technique was 7.7A and it was possible to confirm that 95% was stored within 30A. This paper describes a method and validity of the load forecasting technology in the power distribution system.

Sano, Tsuneyo; Tezuka, Itsuko; Fukuda, Yoshihiro

327

PowerPACK: A wireless power distribution system for wearable devices  

Microsoft Academic Search

Motivated by the prevalence of small, battery-powered devices in many pervasive computing research and deployment scenarios, and the frustration encountered when a particular device is found to be useless due to a discharged internal battery, we present a backpack-worn wireless (non-contact) power distribution system. This system is designed to distribute power from a single point of generation or bulk storage

Travis Deyle; Matthew Reynolds

2008-01-01

328

Distributed Static Compensator with fuel cell for power quality improvement and hybrid power generation  

Microsoft Academic Search

This paper presents analysis and design of Distributed STATic COMpensator (DSTATCOM) with fuel cell utilized for power quality improvement and hybrid power generation. Factors affecting the performance and limitation of active and reactive power compensation are analyzed and presented in this paper. A boost converter circuit is selected to step up and regulate the fuel cell terminal voltage to match

Peerapon Chanhom; Siriroj Sirisukprasert

2009-01-01

329

Quality monitoring of electrical power distribution network using a low-power microcontroller  

Microsoft Academic Search

This paper presents a system for monitoring the electrical disturbances which are present every day in electrical power distribution networks. A simple solution for detecting the disturbances using a low power microcontroller (MSP 430) was developed. The system was devised to work with 230 V 50 Hz electrical power networks in Europe.

C. Dughir; V. Groza; A. Vartosu; G. Prostean

2009-01-01

330

An integrated dc-dc power converter for use in distributed generation power systems  

Microsoft Academic Search

Distributed generation (DG) power systems are becoming increasingly attractive as alternatives to traditional centralized power systems. Fuel cells are an important resource that can be used in such systems, but power electronic converter interfaces are needed to ensure that fuel cells can provide fixed and regulated output voltages as the output of a fuel cell can vary with load. Given

Pritam Das; Gerry Moschopoulos

2008-01-01

331

Influence of distributed generations and renewable energy resources power plant on power system transient stability  

Microsoft Academic Search

This paper analyzing influence of distributed generation (DG) on transient stability of power system network operating parallel with large renewable energy resources (RES) power plant. The study is performed in hypothetical power system network envision in the future which contains a large number of DG. Network behavior when subjected to disturbance is compared with different level of DG penetration. The

Mohd Zamri Che Wanik; István Erlich; Azah Mohamed; Azuki Abdul Salam

2010-01-01

332

Increased deposition of polychlorinated biphenyls (PCBs) under an AC high-voltage power line  

NASA Astrophysics Data System (ADS)

There is considerable public concern regarding the potential risks to health of electromagnetic fields in general and high-voltage power lines in particular. As epidemiological findings are not supported by a clearly defined mechanism of direct magnetic field interactions with the human body, potential indirect effects are of interest. It has been suggested that an increased exposure to chemical pollutants could occur near high-voltage power lines due to formation and deposition of charged aerosols. The current study reports empirical evidence that seems to support this hypothesis. The deposition of 18 congeners of polychlorinated biphenyls (PCBs) was studied by collecting samples of pine needles under a 400 kV AC power line and at reference sites in the vicinity. Compared to the reference sites, the average deposition of PCB congeners under the power line was almost double. This difference between the two groups of samples was statistically significant. While it is premature to draw any conclusions regarding the human exposure near high-voltage power lines, the issue deserves attention and further investigations.

Öberg, Tomas; Peltola, Pasi

2009-12-01

333

Waveform magnetic field survey in Russian DC and Swiss AC powered trains: a basis for biologically relevant exposure assessment.  

PubMed

Recent epidemiological studies suggest a link between transport magnetic fields (MF) and certain adverse health effects. We performed measurements in workplaces of engineers on Russian DC and Swiss AC powered (16.67 Hz) electric trains using a computer based waveform capture system with a 200 Hz sampling rate. MF in DC and AC trains show complex combinations of static and varying components. The most probable levels of quasistatic MF (0.001-0.03 Hz) were in the range 40 microT. Maximum levels of 120 microT were found in DC powered locomotives. These levels are much higher than the geomagnetic field at the site of measurements. MF encountered both in DC and AC powered rail systems showed irregular temporal variability in frequency composition and amplitude characteristics across the whole frequency range studied (0-50 Hz); however, more than 90% of the magnetic field power was concentrated in frequencies AC locomotives, such as the most popular engine Re 4/4 II, the major energy falls around the fundamental frequency 16.67 Hz, with an average magnetic field intensity of about 44 microT; moreover, a significant contribution (about 15%) is due to components below the fundamental frequency. In Russian DC powered trains amplitudes of field variations sharply decrease from static to approximately 3-4 Hz fields; for higher frequencies a tendency of slow decrease is observed up to 50 Hz. For frequencies higher than 1 Hz average amplitudes of magnetic field variations are less than 1 microT; maximum levels reach tens of microtesla. At frequencies lower than 15 Hz, the average magnetic field generated by Swiss AC powered locomotives was approximately 10 times greater than fields observed in Russian DC powered trains. PMID:14603474

Ptitsyna, N G; Kopytenko, Y A; Villoresi, G; Pfluger, D H; Ismaguilov, V; Iucci, N; Kopytenko, E A; Zaitzev, D B; Voronov, P M; Tyasto, M I

2003-12-01

334

Distributed photovoltaic generation in residential distribution systems: Impacts on power quality and anti-islanding  

NASA Astrophysics Data System (ADS)

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.

Mitra, Parag

335

Power Sharing Control between Load-Side Inverters in DC Microgrid for Super High Quality Electric Power Distribution System  

Microsoft Academic Search

DC microgrid is a novel power system using dc distribution in order to provide a super high quality electric power. The dc distribution system is suitable for dc output type distributed generations such as photovoltaic and fuel cells, and energy storages such as batteries and electric double layer capacitors. Power is distributed through dc distribution line and converted to required

Hiroaki Kakigano; Kaho Nada; Yushi Miura; Toshifumi Ise; Ryohei Uchida

2008-01-01

336

A High-Performance Multicell Topology Based on Single-Phase Power Cells for Three-Phase Systems Operating Under Unbalanced AC Mains and Asymmetrical Loads  

Microsoft Academic Search

This paper presents a multicell converter topology composed of N single-phase power cells per phase and a multipulse power transformer. The topology achieves high-power-quality waveforms in three-phase applications under the presence of severe unbalanced ac mains. Moreover, the power cells are properly arranged in order to achieve high-performance ac supply current waveforms under asymmetrical loads. The configuration is based on

Carlos R. Baier; José R. Espinoza; Javier A. Munoz; Luis A. Moran; Pedro E. Melin

2010-01-01

337

Automation of the Athens (Tennessee) electric power distribution system  

SciTech Connect

A large scale distribution automation research and development project has been conducted at the Athens Utilities Board (AUB) in Athens, Tennessee. The project goal was to experiment with the integrated monitoring and control of an entire distribution system from a central distribution control center. The project was sponsored by the U.S. Department of Energy, Office of Energy Storage and Distribution, Electric Energy Systems Program and managed by the Oak Ridge National Laboratory. The experience with the distribution substation monitoring and control, feeder monitoring, voltage and reactive power (vary) control, system (or circuit) reconfiguration for emergency and maintenance situations, and load control are described. A distribution automation applications software package for assessing system configuration, and volt/var control on automated radial distribution feeders was developed and is also described. 8 refs.

Rizy, D.T.; Stovall, J.P.; Usry, G.H.

1988-01-01

338

A novel four-branches-inverter-based-active-filter for harmonic suppression and reactive compensation of an unbalanced three-phase four-wires electrical distribution systems, feeding AC\\/DC loads  

Microsoft Academic Search

This paper deals with the design, analysis and digital simulation of a novel four-branches-inverter-based-active-filter, that compensates the reactive power and suppress the harmonic currents in the phases and neutral of an unbalanced three-phase four-wires electrical distribution system, feeding AC\\/DC loads. That is, the filter has the capability to instantaneously suppress the harmonics currents, in both the three-phases and the neutral,

Alfredo Nava-Segura; G. Mino-Aguilar

2000-01-01

339

Power laws, discontinuities and regional city size distributions  

USGS Publications Warehouse

Urban systems are manifestations of human adaptation to the natural environment. City size distributions are the expression of hierarchical processes acting upon urban systems. In this paper, we test the entire city size distributions for the southeastern and southwestern United States (1990), as well as the size classes in these regions for power law behavior. We interpret the differences in the size of the regional city size distributions as the manifestation of variable growth dynamics dependent upon city size. Size classes in the city size distributions are snapshots of stable states within urban systems in flux. ?? 2008.

Garmestani, A. S.; Allen, C. R.; Gallagher, C. M.

2008-01-01

340

VST primary mirror active optics power distribution system  

NASA Astrophysics Data System (ADS)

The VST (VLT Survey Telescope), a 2.6 m class Alt-Az telescope in installation phase on Cerro Paranal in Northern Chile, at the European Southern Observatory (ESO) site, is provided with a distributed control system based on electro-mechanical actuators, aimed at implementing the main mirror active optics. Due to the requirement of dissipated power reduction under the mirror, a regulated power bus has been chosen, avoiding the use of voltage regulators mounted on the actuators control board. Because the parallel connection of the all control boards power lines makes this solution critical from the point of view of cabling drop voltage and fault propagation, a Power Distribution System (PDS) provided with remote monitoring and control capabilities has been designed. The PDS configuration is based on several Power Distribution Boxes (PDBs), connected in two separate benches. The harness accommodation was estimated by means of 3D CAD, to evaluate the length of the single power connections. The cabling drop voltage was verified by means of PSpice simulation. The single PDS bench has been provided with drop voltage remote sensing function for all the power supply voltages, while the single PDB has been provided with control and monitoring electronics to disconnect via tele-command the faulty control boards and to monitor in real time voltages and current consumption.

Molfese, C.; Busatta, A.

2008-08-01

341

Connecting an alternative energy source to the power grid by a DSP controlled DC\\/AC inverter  

Microsoft Academic Search

In times when environmental issues such as global warming and air pollution are in focus, there are more objections to the use of conventional and nuclear power stations. The use of alternative energy sources such as water turbines, solar cells and wind turbines becomes essential for producing clean energy. In this paper, a novel design of a 1 kW DC\\/AC

Yuval Beck; Bishara Bishara; Dror Medini

2005-01-01

342

Conditions for self-sustained oscillations in feedback control of AC motor speed by power electronic controllers  

Microsoft Academic Search

Speed control of AC induction motors by power electronic controllers is considered. The basic method of speed control is obtained by application of variable frequencies to the motor. Certain parameters are subject to modification by the user in the field. A model of the resulting operation is shown to contain a specific nonlinearity. In feedback applications the interaction of the

Robert L. Drake

2003-01-01

343

Comparison of Wind Power and Load Forecasting Error Distributions: Preprint  

SciTech Connect

The introduction of large amounts of variable and uncertain power sources, such as wind power, into the electricity grid presents a number of challenges for system operations. One issue involves the uncertainty associated with scheduling power that wind will supply in future timeframes. However, this is not an entirely new challenge; load is also variable and uncertain, and is strongly influenced by weather patterns. In this work we make a comparison between the day-ahead forecasting errors encountered in wind power forecasting and load forecasting. The study examines the distribution of errors from operational forecasting systems in two different Independent System Operator (ISO) regions for both wind power and load forecasts at the day-ahead timeframe. The day-ahead timescale is critical in power system operations because it serves the unit commitment function for slow-starting conventional generators.

Hodge, B. M.; Florita, A.; Orwig, K.; Lew, D.; Milligan, M.

2012-07-01

344

An Improved Power-Quality 30Pulse AC–DC for Varying Loads  

Microsoft Academic Search

This paper presents the design and analysis of a novel 30-pulse ac-dc converter for harmonic mitigation under varying loads. The proposed 30-pulse ac-dc converter is based on a polygon-connected autotransformer with reduced magnetics. The proposed ac-dc converter is able to eliminate lower than 29th order harmonics in the ac supply current. The resulting supply current is near sinusoidal in shape

Bhim Singh; G. Bhuvaneswari; Vipin Garg

2007-01-01

345

Resonant AC power system proof-of-concept test program, volume 2, appendix 1  

NASA Technical Reports Server (NTRS)

This report contains two volumes. The main text (Volume 1) summarizes the tests results and gives a detailed discussion of the response of three early, first generation configurations of ac power system IRAD breadboards to the contracted tests imposed on them. It explains photographs, measurements, and data calculations, as well as any observed anomalies or lessons learned. This volume (No 2, Appendix 1, Test Results and Data), published under separate cover, includes all of the data taken on the 1.0 kW single-phase; 5.0 kW three-phase; and 25.0-kW three-phase system breadboards. The format of this data is raw, i.e., it is a direct copy of the data sheets for the test data notebook.

1986-01-01

346

Voltage source ac-to-dc converters for high-power transmitters  

NASA Technical Reports Server (NTRS)

This work was done to optimize the design of the components used for the beam power supply, which is a component of the transmitters in the Deep Space Network (DSN). The major findings are: (1) the difference in regulation between a six-pulse and a twelve-pulse converter is at most 7 percent worse for the twelve-pulse converter; (2) the commutation overlap angle of a current source converter equals that of a voltage source converter with continuous line currents; (3) the sources of uncharacteristic harmonics are identified with SPICE simulation; (4) the use of an imperfect phase-shifting transformer for the twelve-pulse converter generates a harmonic at six times the line frequency; and (5) the assumptions usually made in analyzing converters can be relaxed with SPICE simulation. The results demonstrate the suitability of using SPICE simulation to obtain detailed performance predictions of ac-to-dc converters.

Cormier, R.

1990-01-01

347

High-power distributed-feedback quantum cascade lasers  

Microsoft Academic Search

Whereas high-power operation (> 1 W of cw output power at 200 K) has been demonstrated for quantum cascade lasers emitting at lambda = 4.7-6.2 mum, those devices generally exhibited multiple longitudinal modes. Recently, a distributed-feedback quantum cascade laser operating in a single spectral mode at lambda = 4.8 mum and at temperatures up to 333 K has been reported.

W. W. Bewley; I. Vurgaftman; C. S. Kim; J. R. Meyer; J. Nguyen; A. J. Evans; J. S. Yu; S. R. Darvish; S. Slivken; M. Razeghi

2006-01-01

348

Design methodology for multiple domain power distribution systems  

Microsoft Academic Search

High-speed digital devices require multiple voltage and frequency domains to accommodate the core logic and the input\\/output (I\\/O) circuitry for multiple interfaces. In addition, some of these interfaces are programmable to various speeds and signaling modes and they require multiple power supply voltages. These requirements create complex power delivery and signal distribution solutions. This paper proposes a design methodology for

Nam Pham; Moises Cases; Daniel de Araujo; Erdem Matoglu

2004-01-01

349

Subsystem design in aircraft power distribution systems using optimization  

NASA Astrophysics Data System (ADS)

The research reported in this dissertation focuses on the development of optimization tools for the design of subsystems in a modern aircraft power distribution system. The baseline power distribution system is built around a 270V DC bus. One of the distinguishing features of this power distribution system is the presence of regenerative power from the electrically driven flight control actuators and structurally integrated smart actuators back to the DC bus. The key electrical components of the power distribution system are bidirectional switching power converters, which convert, control and condition electrical power between the sources and the loads. The dissertation is divided into three parts. Part I deals with the formulation of an optimization problem for a sample system consisting of a regulated DC-DC buck converter preceded by an input filter. The individual subsystems are optimized first followed by the integrated optimization of the sample system. It is shown that the integrated optimization provides better results than that obtained by integrating the individually optimized systems. Part II presents a detailed study of piezoelectric actuators. This study includes modeling, optimization of the drive amplifier and the development of a current control law for piezoelectric actuators coupled to a simple mechanical structure. Linear and nonlinear methods to study subsystem interaction and stability are studied in Part III. A multivariable impedance ratio criterion applicable to three phase systems is proposed. Bifurcation methods are used to obtain global stability characteristics of interconnected systems. The application of a nonlinear design methodology, widely used in power systems, to incrementally improve the robustness of a system to Hopf bifurcation instability is discussed.

Chandrasekaran, Sriram

2000-10-01

350

Electrical Power Distribution and Control Modeling and Analysis  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the use of Electrical Power Distribution and Control (EPD&C) Modeling and how modeling can support analysis. The presentation discusses using the EASY5 model to simulate and analyze the Space Shuttle Electric Auxiliary Power Unit. Diagrams of the model schematics are included, as well as graphs of the battery cell impedance, hydraulic load dynamics, and EPD&C response to hydraulic load variations.

Fu, Johnny S.; Liffring, Mark; Mehdi, Ishaque S.

2001-01-01

351

Nearly Unity Power-Factor of the Modular Three-Phase AC to DC Converter with Minimized DC Bus Capacitor  

Microsoft Academic Search

The analysis and design of nearly unity power-factor and fast dynamic response of the modular three-phase ac to dc converter using three single-phase isolated SEPIC rectifier modules with minimized dc bus capacitor is discussed, based on power balance control technique. The averaged small-signal technique is used to obtain the inductor current compensator, thus resulting in the output impedance and audio

Viboon Chunkag; Uthen Kamnarn

2008-01-01

352

Nearly Unity Power-Factor of the Modular Three-Phase AC to DC Converter with Minimized DC Bus Capacitor  

Microsoft Academic Search

The analysis and design of nearly unity power-factor and fast dynamic response of the modular three-phase ac to dc converter using three single-phase isolated SEPIC rectifier modules with minimized dc bus capacitor is discussed, based on power balance control technique. The averaged small-signal technique is used to obtain the inductor current compensator, thus resulting in the output impedance and audio

U. Kamnarn; V. Chunkag

2007-01-01

353

Power law distribution of dividends in horse races  

NASA Astrophysics Data System (ADS)

We discovered that the distribution of dividends in Korean horse races follows a power law. A simple model of betting is proposed, which reproduces the observed distribution. The model provides a mechanism to arrive at the true underlying winning probabilities, which are initially unknown, in a self-organized collective fashion, through the dynamic process of betting. Numerical simulations yield excellent agreement with the empirical data.

Park, K.; Domany, E.

2001-02-01

354

Power-law distribution of family names in Japanese societies  

NASA Astrophysics Data System (ADS)

We study the frequency distribution of family names. From a common data base, we count the number of people who share the same family name. This is the size of the family. We find that (i) the total number of different family names in a society scales as a power law of the population, (ii) the total number of family names of the same size decreases as the size increases with a power law and (iii) the relation between size and rank of a family name also shows a power law. These scaling properties are found to be consistent for five different regional communities in Japan.

Miyazima, Sasuke; Lee, Youngki; Nagamine, Tomomasa; Miyajima, Hiroaki

2000-04-01

355

Proposal of an Innovative Electric Power Distribution System based on Packet Power Transactions  

NASA Astrophysics Data System (ADS)

Recently, the introduction of decentralized generators, such as photovoltaic power generations, has been promoted rapidly. In the future, extensive use of PV is thought to give rise to the daytime surplus electricity, and a household will manage the surplus electricity rationally. The purpose of this research is to propose an innovative electric power distribution system based on packet power transactions. First, this paper explains distributed markets of which the price can easily reflect the geographical diversity of renewable energy availability and load curve characteristic within the local area. Second, this paper exemplifies the specific electronic circuit that makes pulse-shaped power transmission to develop the packet power distribution system. Finally, this paper shows the results of multi-agent simulations of electricity trading to evaluate the usefulness of the proposed system.

Inoue, Jun; Fujii, Yasumasa

356

Load Frequency Control in Power System with Distributed Generation  

NASA Astrophysics Data System (ADS)

This paper proposes a method to improve the load frequency control in a power system with distributed generation (DG). DG is assumed to include photovoltaic generation, wind power generation, fuel cells and etc. In this paper, a simulation is performed using a microgrid model or island model that is composed of a storage system with either wind power generation or photovoltaic generation system as the DG. The effectiveness of load frequency control (LFC) using a storage system is examined using a power transmission simulator. The model for the experiment has been composed of inverter, battery, synchronous generator and load. Using this model, the comparison examination was done in respect of output setting control and the case in which the PI control was used. As a result, when the output set-point control using power demand estimation method is executed, the control characteristic is very excellent.

Yukita, Kazuto; Ota, Takuya; Fujimoto, Koji; Goto, Yasuyuki; Ichiyanagi, Katuhiro

357

Body fat distribution in women with familial partial lipodystrophy caused by mutation in the lamin A/C gene  

PubMed Central

Familial partial lipodystrophy (FPLD), Dunnigan variety, is an autosomal dominant disorder caused due to missense mutations in the lamin A/C (LMNA) gene encoding nuclear lamina proteins. Patients with FPLD are predisposed to metabolic complications of insulin resistance such as diabetes. We sought to evaluate and compare body fat distribution with dual-emission X-ray absorptiometry in women with and without FPLD and identify densitometric, clinical and metabolic features.

Monteiro, Luciana Z.; Foss-Freitas, Maria C.; Junior Montenegro, Renan M.; Foss, Milton C.

2012-01-01

358

Evaluation of power control concepts using the PMAD systems test bed. [Power Management and Distribution  

NASA Technical Reports Server (NTRS)

The Lewis Research Center's Power Management and Distribution (PMAD) System testbed and its use in the evaluation of control concepts applicable to the NASA Space Station Freedom electric power system (EPS) are described. The facility was constructed to allow testing of control hardware and software in an environment functionally similar to the space station electric power system. Control hardware and software have been developed to allow operation of the testbed power system in a manner similar to a supervisory control and data acquisition (SCADA) system employed by utility power systems for control. The system hardware and software are described.

Beach, R. F.; Kimnach, G. L.; Jett, T. A.; Trash, L. M.

1989-01-01

359

Hierarchical microgrid paradigm for integration of distributed energy resources  

Microsoft Academic Search

This paper describes an approach to hierarchical integration of DC and AC microgrids containing distributed energy resources (DERs) into the existing electric power distribution infrastructure. Power electronic interfaces and controls permit the aggregated units at each level to represent themselves to a higher level as a single self-controlled entity (DC or AC, load or generator). At the top level of

Zhenhua Jiang; Roger A. Dougal

2008-01-01

360

An architecture for a power-aware distributed microsensor node  

Microsoft Academic Search

Networks of distributed microsensors are emerging as a compelling solution for a wide range of data gathering applications. Perhaps the most substantial challenge facing designers of small but long-lived microsensor nodes is the need for significant reductions in energy consumption. We propose a power-aware design methodology that emphasizes the graceful scalability of energy consumption with factors such as available resources,

Rex Min; Manish Bhardwaj; Seong-Hwan Cho; Amit Sinha; Eugene Shih; Alice Wang; Anantha Chandrakasan

2000-01-01

361

ALSTOM Hellas experience on power and distribution transformers  

Microsoft Academic Search

Magnetic materials and application of these in industry is a very important subject for study and discussion. In industry, one of the most important applications of magnetic steel is the core construction for power and distribution transformers. In this article we try to transfer our experience about the use of magnetic materials in core construction and we give also a

J Kyriakakis

2001-01-01

362

Power system modeling requirements for rotating machine interfaced distributed resources  

Microsoft Academic Search

Rotating machine interfaced power generation equipment today constitute the majority of interconnected distributed resources (DR). Even though new electronically interfaced DR devices, such as fuel cells, photovoltaics and microturbines are rapidly emerging, rotating machines are expected to continue to represent a major sector of interconnected DR capacity for the foreseeable future. To simulate and predict the impacts of these machines

Philip P. Barker; Bradley K. Johnson

2002-01-01

363

Power-Law Distribution for Solar Energetic Proton Events  

NASA Astrophysics Data System (ADS)

Analyses of the time-integrated fluxes of solar energetic particle events during the period 1965 1990 show that the differential distribution of events with flux F is given by a power law, with indices between 1.2 and 1.4 depending on energy. The power law represents a good fit over three to four orders of magnitude in fluence. Similar power-law distributions have been found for peak proton and electron fluxes, X-ray flares and radio and type III bursts. At fluences greater than 109 cm-2, the slope of the distribution steepens and beyond 1010 cm-2 the power-law index is estimated to be 3.5. At energies greater than 10 MeV, the slope of the distribution was found to be essentially independent of solar cycle, when the active years of solar cycles 20, 21, and 22 were analysed. The results presented are the first for a complete period of 27 years, covering nearly 3 complete solar cycles. Other new aspects of the results include the invariance of the exponent with solar cycle and also with integral energy.

Gabriel, S. B.; Feynman, J.

1996-05-01

364

Power electronics interfaces for low voltage distribution generation — EMC issues  

Microsoft Academic Search

In recent years there is observed an intensive growth of activities in matter of bidirectional electrical energy distribution systems. In situation of fast industrial progress the Electrical Power System (EPS) has to be developed to meet energy demand. This development in accordance to new environmental requirements (1) should be managed very cleaver. Because of these the participation of small renewable

Robert Smolenski; Marcin Jarnut; Grzegorz Benysek; Adam Kempski

2011-01-01

365

Radial distribution system power flow using interval arithmetic  

Microsoft Academic Search

This paper reports on the application of interval arithmetic technique for balanced radial distribution system power flow analysis. Interval arithmetic takes care of the uncertainty in the input parameters and provides strict bounds for the solution of the problem. In this paper, uncertainties only in the input load parameters are considered. The results are compared with the results obtained from

Biswarup Das

2002-01-01

366

High Resolution PV Power Modeling for Distribution Circuit Analysis  

SciTech Connect

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.

Norris, B. L.; Dise, J. H.

2013-09-01

367

A robust power flow algorithm for radial distribution systems  

Microsoft Academic Search

In this paper, a new algorithm is presented to solve the power flow problem in radial distribution systems. The proposed method takes into account the voltage dependency of static loads, and line charging capacitance. The method is based on the forward and backward voltage calculation by using polynomial voltage equation and KirchofPs Law for each branch. Convergence speed and reliability

U. Eminoglu; M. H. Hocaoglu

2005-01-01

368

Application of continuation power flow method in radial distribution systems  

Microsoft Academic Search

The paper presents a set of equations (SOE) comprising voltage magnitude and nodal real\\/reactive power balance equations to model a radial distribution system (RDS). The voltage equations in the SOE have dual roots. Then a Newton–Raphson (NR) method is presented to solve the SOE to determine the voltage solution of an RDS. This NR method is extended using the continuation

A. Dukpa; B. Venkatesh; M. El-Hawary

2009-01-01

369

HEMP field coupling with buried power distribution cables  

Microsoft Academic Search

The interaction of transient electromagnetic field due to HEMP with multicore buried power distribution cables is studied in this paper. Using transmission line analysis, the induced current on the shield of the cable is computed. The cable transfer impedance is used to find the coupled current in the inner circuit. The variation of the current induced on the inner conductor

K. Sunitha; M. Joy Thomas

2009-01-01

370

The role of distributed generation in restructured power systems  

Microsoft Academic Search

This paper presents a review of the role of distributed generation (DG) in restructured power systems, and has two parts. The first part reviews reasons behind DG deployment for utilities and customers, as well as new issues and concerns arise once DG penetration level increases. The second part of the paper presents a case study simulating the effect of DG

M. H. Albadi; E. F. El-Saadany

2008-01-01

371

Impacts of distributed generation on power system transient stability  

Microsoft Academic Search

It is expected that increasing amounts of new generation technologies will be connected to electrical power systems in the near future. Most of these technologies are of considerably smaller scale than conventional synchronous generators and are therefore connected to distribution grids. Further, many are based on technologies different from the synchronous generator, such as the squirrel cage induction generator and

J. G. Slootweg; W. L. Kling

2002-01-01

372

Potential benefits of distributed generators to power systems  

Microsoft Academic Search

With the growing awareness of environmental protection, energy savings, and economic scenarios, distributed generators (DGs) have been playing an increasingly important role in power systems (PSs) all over the world. DGs applications in and potential impacts on PSs have been paid more and more attention in recent years. However, the potential benefits of DGs on PSs have not yet been

Zhipeng Liu; Fushuan Wen; Gerard Ledwich

2011-01-01

373

Application of optical communications for power distribution companies  

Microsoft Academic Search

Optical fibers used in electric power distribution companies are described. There are two kinds of optical fibers used along with grounding wires; one is called the built-in type, in which optical fibers are inserted in the core part of one grounding wire, and one other is called the winding type, in which the optical fiber cable is wound around existing

H. Murata

1990-01-01

374

Pointers and linked lists in electric power distribution circuit analysis  

Microsoft Academic Search

Electric power distribution circuit analysis programs must efficiently manage a large quantity of system and equipment data. Utility engineers now wish to use integrated software packages with several functions that work efficiently and share data. The use of data structures stored in linked lists and processed through pointers is described. The pointers and linked lists compact the data storage and

R. P. Broadwater; J. C. Thompson; T. E. McDermott

1991-01-01

375

Raptor electrocutions-emerging issues [overhead power distribution  

Microsoft Academic Search

The electrocution of raptors and larger perching birds is a hazard of overhead distribution construction, especially in the Western United States where poles in treeless areas make attractive perches. Disturbed by the continuing large numbers of raptors, particularly eagles, electrocuted along power lines, the US Fish and Wildlife (SFWS) has begun to step up enforcement of the Migratory Bird Treaty

Richard E. Harness

2000-01-01

376

Determining and exploiting the distribution function of wind power forecasting error for the economic operation of autonomous power systems  

Microsoft Academic Search

Many efforts have been presented in the bibliography for wind power forecasting in power systems and few of them have been used for autonomous power systems. The impact of knowing the distribution function of wind power forecasting error in the economic operation of a power system is studied in this paper. The papers proposes that the distribution of the wind

Antonis G. Tsikalakis; Yiannis A. Katsigiannis; Pavlos S. Georgilakis; Nikos D. Hatziargyriou

2006-01-01

377

Virtual Power Plant: New Solution for Managing Distributed Generations in Decentralized Power Systems  

Microsoft Academic Search

The presence of distributed generation poses new challenges in the management and operation of electrical grids. Distributed generation (wind, combined heat and power, etc.) already accounts for 20% or more of total generation in some electric utilities and this figure is constantly increasing worldwide. With the advent of environmental friendly, small size and efficient generators close to the loads new

Mohamad Amin Salmani; Arash Anzalchi; Soudeh Salmani

2010-01-01

378

Electron beam machining using rotating and shaped beam power distribution  

DOEpatents

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.

Elmer, John W. (Pleasanton, CA); O'Brien, Dennis W. (Livermore, CA)

1996-01-01

379

Exploring empowerment in settings: mapping distributions of network power.  

PubMed

This paper brings together two trends in the empowerment literature-understanding empowerment in settings and understanding empowerment as relational-by examining what makes settings empowering from a social network perspective. Specifically, extending Neal and Neal's (Am J Community Psychol 48(3/4):157-167, 2011) conception of network power, an empowering setting is defined as one in which (1) actors have existing relationships that allow for the exchange of resources and (2) the distribution of network power among actors in the setting is roughly equal. The paper includes a description of how researchers can examine distributions of network power in settings. Next, this process is illustrated in both an abstract example and using empirical data on early adolescents' peer relationships in urban classrooms. Finally, implications for theory, methods, and intervention related to understanding empowering settings are explored. PMID:24213301

Neal, Jennifer Watling

2014-06-01

380

Statistical Models of Power-law Distributions in Homogeneous Plasmas  

SciTech Connect

A variety of in-situ measurements in space plasmas point out to an intermittent formation of distribution functions with elongated tails and power-law at high energies. Power-laws form ubiquitous signature of many complex systems, plasma being a good example of a non-Boltzmann behavior for distribution functions of energetic particles. Particles, which either undergo mutual collisions or are scattered in phase space by electromagnetic fluctuations, exhibit statistical properties, which are determined by the transition probability density function of a single interaction, while their non-asymptotic evolution may determine the observed high-energy populations. It is shown that relaxation of the Brownian motion assumptions leads to non-analytical characteristic functions and to generalization of the Fokker-Planck equation with fractional derivatives that result in power law solutions parameterized by the probability density function.

Roth, Ilan [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)

2011-01-04

381

Electron beam machining using rotating and shaped beam power distribution  

DOEpatents

An apparatus and method are disclosed 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 1,000 {micro}m (1 mm or larger), compared to the 250 {micro}m diameter of laser drilling. 5 figs.

Elmer, J.W.; O`Brien, D.W.

1996-07-09

382

Distributed algorithms for monitoring and control of electric power transmission and distribution systems  

SciTech Connect

The benefits of distributed computing systems are massively increased computing power and improved reliability. Distributed computing systems are particularly attractive for monitoring and control of large-scale electric power transmission and distribution systems. In this dissertation two aspects of distributed computing have been investigated. First, a distributed software model for the implementation of network security functions in energy management systems is proposed. Second, a theoretical framework for the development of distributed algorithms is developed. The framework is applied to some of the functions necessary for the operation of an automated power distribution system. The proposed distributed model for the software of energy management systems is based on the object-oriented methodology. A prototype implementation of the power flow function is described as a concrete example for the application of the model. Other network security functions discussed are state estimation and bad data detection. The proposed model reduces the effort of development and maintenance of large-scale energy management system software. It provides a tool for coping with the constantly increasing complexity of these software systems. A framework for the development of distributed algorithms is proposed. A special class of separable continuous constrained optimization problems is considered. A class of asynchronous iterative algorithms is developed. The solution of the separable continuous constrained optimization problem is emphasized because many problems arising in the operation of an automated distribution system can be formulated as constrained optimization problems. It is shown that these optimization problems can be solved with a set of largely independent processors which exchange a minimum of information.

Neyer, A.F.

1989-01-01

383

Multi-kw dc power distribution system study program  

NASA Technical Reports Server (NTRS)

The first phase of the Multi-kw dc Power Distribution Technology Program is reported and involves the test and evaluation of a technology breadboard in a specifically designed test facility according to design concepts developed in a previous study on space vehicle electrical power processing, distribution, and control. The static and dynamic performance, fault isolation, reliability, electromagnetic interference characterisitics, and operability factors of high distribution systems were studied in order to gain a technology base for the use of high voltage dc systems in future aerospace vehicles. Detailed technical descriptions are presented and include data for the following: (1) dynamic interactions due to operation of solid state and electromechanical switchgear; (2) multiplexed and computer controlled supervision and checkout methods; (3) pulse width modulator design; and (4) cable design factors.

Berkery, E. A.; Krausz, A.

1974-01-01

384

Learning geotemporal nonstationary failure and recovery of power distribution.  

PubMed

Smart energy grid is an emerging area for new applications of machine learning in a nonstationary environment. Such a nonstationary environment emerges when large-scale failures occur at power networks because of external disruptions such as hurricanes and severe storms. Power distribution networks lie at the edge of the grid, and are especially vulnerable to external disruptions. Quantifiable approaches are lacking and needed to learn nonstationary behaviors of large-scale failure and recovery of power distribution. This paper studies such nonstationary behaviors in three aspects. First, a novel formulation is derived for an entire life cycle of large-scale failure and recovery of power distribution. Second, spatial-temporal models of failure and recovery of power distribution are developed as geolocation-based multivariate nonstationary GI(t)/G(t)/? queues. Third, the nonstationary spatial-temporal models identify a small number of parameters to be learned. Learning is applied to two real-life examples of large-scale disruptions. One is from Hurricane Ike, where data from an operational network is exact on failures and recoveries. The other is from Hurricane Sandy, where aggregated data is used for inferring failure and recovery processes at one of the impacted areas. Model parameters are learned using real data. Two findings emerge as results of learning: 1) failure rates behave similarly at the two different provider networks for two different hurricanes but differently at the geographical regions and 2) both the rapid and slow-recovery are present for Hurricane Ike but only slow recovery is shown for a regional distribution network from Hurricane Sandy. PMID:24806656

Wei, Yun; Ji, Chuanyi; Galvan, Floyd; Couvillon, Stephen; Orellana, George; Momoh, James

2014-01-01

385

Distributed generation modeling for power flow studies and a three-phase unbalanced power flow solution for radial distribution systems considering distributed generation  

Microsoft Academic Search

Distributed generations (DGs) are generally modeled as PV or PQ nodes in power flow studies (PFSs) for distribution system. Determining a suitable model for each DG unit requires knowing the DG operation and the type of its connection to the grid (direct or indirect). In this respect, this paper offers a helpful list of DG models for PFSs. Moreover, an

S. M. Moghaddas-Tafreshi; Elahe Mashhour

2009-01-01

386

Pulse doubling in zigzag-connected autotransformer-based 12-pulse ac-dc converter for power quality improvement  

NASA Astrophysics Data System (ADS)

This paper presents a pulse doubling technique in a 12-pulse ac-dc converter which supplies direct torque controlled motor drives (DTCIMDs) in order to have better power quality conditions at the point of common coupling. The proposed technique increases the number of rectification pulses without significant changes in the installations and yields in harmonic reduction in both ac and dc sides. The 12-pulse rectified output voltage is accomplished via two paralleled six-pulse acdc converters each of them consisting of three-phase diode bridge rectifiers. An autotransformer is designed to supply the rectifiers. The design procedure of magnetics is in a way such that makes it suitable for retrofit applications where a six-pulse diode bridge rectifier is being utilized. Independent operation of paralleled diode-bridge rectifiers, i.e. dc-ripple re-injection methodology, requires a Zero Sequence Blocking Transformer (ZSBT). Finally, a tapped interphase reactor is connected at the output of ZSBT to double the pulse numbers of output voltage up to 24 pulses. The aforementioned structure improves power quality criteria at ac mains and makes them consistent with the IEEE-519 standard requirements for varying loads. Furthermore, near unity power factor is obtained for a wide range of DTCIMD operation. A comparison is made between 6-pulse, 12-pulse, and proposed converters from view point of power quality indices. Results show that input current total harmonic distortion (THD) is less than 5% for the proposed topology at various loads.

Abdollahi, Rohollah

2012-12-01

387

Distributed renewable power from biomass and other waste fuels  

NASA Astrophysics Data System (ADS)

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.

Lyons, Chris

2012-03-01

388

Distributed control of reactive power flow in a radial distribution circuit with high photovoltaic penetration  

SciTech Connect

We show how distributed control of reactive power can serve to regulate voltage and minimize resistive losses in a distribution circuit that includes a significant level of photovoltaic (PV) generation. To demonstrate the technique, we consider a radial distribution circuit with a single branch consisting of sequentially-arranged residential-scale loads that consume both real and reactive power. In parallel, some loads also have PV generation capability. We postulate that the inverters associated with each PV system are also capable of limited reactive power generation or consumption, and we seek to find the optimal dispatch of each inverter's reactive power to both maintain the voltage within an acceptable range and minimize the resistive losses over the entire circuit. We assume the complex impedance of the distribution circuit links and the instantaneous load and PV generation at each load are known. We compare the results of the optimal dispatch with a suboptimal local scheme that does not require any communication. On our model distribution circuit, we illustrate the feasibility of high levels of PV penetration and a significant (20% or higher) reduction in losses.

Chertkov, Michael [Los Alamos National Laboratory; Turitsyn, Konstantin [Los Alamos National Laboratory; Backhaus, Scott [Los Alamos National Laboratory; Sule, Petr [NEW MEXICO CONSORTIUM

2009-01-01

389

Power management and distribution considerations for a lunar base  

NASA Technical Reports Server (NTRS)

Design philosophies and technology needs for the power management and distribution (PMAD) portion of a lunar base power system are discussed. A process is described whereby mission planners may proceed from a knowledge of the PMAD functions and mission performance requirements to a definition of design options and technology needs. Current research efforts at the NASA LRC to meet the PMAD system needs for a Lunar base are described. Based on the requirements, the lunar base PMAD is seen as best being accomplished by a utility like system, although with some additional demands including autonomous operation and scheduling and accurate, predictive modeling during the design process.

Kenny, Barbara H.; Coleman, Anthony S.

1991-01-01

390

Application of Genetic Algorithm for the Reduction of Reactive Power Losses in Radial Distribution System  

Microsoft Academic Search

Power losses in distribution system have become the most concerned issue in power losses analysis in any power system. In the effort of reducing power losses within distribution system, reactive power compensation has become increasingly important as it affects the operational, economical and quality of service for electric power systems. This paper presents the application of genetic algorithm approach for

Perumal Nallagownden; L. T. Thin; N. C. Guan; C. M. H. Mahmud

2006-01-01

391

I-BIEM calculations of the frequency dispersion and ac current distribution at disk and ring-disk electrodes  

NASA Technical Reports Server (NTRS)

The Iterative Boundary Integral Equation Method (I-BIEM) has been applied to the problem of frequency dispersion at a disk electrode in a finite geometry. The I-BIEM permits the direct evaluation of the AC potential (a complex variable) using complex boundary conditions. The point spacing was made highly nonuniform, to give extremely high resolution in those regions where the variables change most rapidly, i.e., in the vicinity of the edge of the disk. Results are analyzed with respect to IR correction, equipotential surfaces, and reference electrode placement. The current distribution is also examined for a ring-disk configuration, with the ring and the disk at the same AC potential. It is shown that the apparent impedance of the disk is inductive at higher frequencies. The results are compared to analytic calculations from the literature, and usually agree to better than 0.001 percent.

Cahan, Boris D.

1991-01-01

392

I-BIEM calculations of the frequency dispersion and AC current distribution at disk and ring-disk electrodes  

NASA Technical Reports Server (NTRS)

The Iterative Boundary Integral Equation Method (I-BIEM) has been applied to the problem of frequency dispersion at a disk electrode in a finite geometry. The I-BIEM permits the direct evaluation of the AC potential (a complex variable) using complex boundary conditions. The point spacing was made highly nonuniform, to give extremely high resolution in those regions where the variables change most rapidly, i.e., in the vicinity of the edge of the disk. Results are analyzed with respect to IR correction, equipotential surfaces, and reference electrode placement. The current distribution is also examined for a ring-disk configuration, with the ring and the disk at the same AC potential. It is shown that the apparent impedance of the disk is inductive at higher frequencies. The results are compared to analytic calculations from the literature, and usually agree to better than 0.001 percent.

Cahan, Boris D.

1991-01-01

393

Power distribution for an Am/Cm bushing melter  

SciTech Connect

Decades of nuclear material production at the Savannah River Site (SRS) has resulted in the generation of large quantities of the isotopes Am{sup 243} and Cm{sup 244}. Currently, the Am and Cm isotopes are stored as a nitric acid solution in a tank. The Am and Cm isotopes have great commercial value but must be transferred to ORNL for processing. The nitric acid solution contains other isotopes and is intensely radioactive, which makes storage a problem and precludes shipment in the liquid form. In order to stabilize the material for onsite storage and to permit transport the material from SRS to ORNL, it has been proposed that the Am and Cm be separated from other isotopes in the solution and vitrified. Vitrification will be effected by depositing a liquid feed stream containing the isotopes in solution, together with a stream of glass frit, onto the top of a molten glass pool in a melter. The glass is non-conducting and the melter is a Platinum/Rhodium alloy vessel which is heated by passing an electric current through it. Because most of the power is required to evaporate the liquid feed at the top of the glass pool, power demands differ for the upper and lower parts of the melter. In addition, the melter is batch fed so that the local power requirements vary with time. In order to design a unique split power supply, which ensures adequate local power delivery, an analysis of the melter power distribution was performed with the ABAQUS finite element code. ABAQUS was used to calculate the electric potential and current density distributions in the melter for a variety of current and potential boundary conditions. The results of the calculation were compared with test data and will be used to compute power densities for input to a computational fluid dynamics model for the melter.

Gong, C.; Hardy, B.J.

1996-12-31

394

Power-law distribution in Japanese racetrack betting  

NASA Astrophysics Data System (ADS)

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 Po(x) indicates a clear power-law Po(x)?1/x, where x represents the final odds. This power-law can be explained on the basis of the assumption that every bettor bets his money on the horse that appears to be the strongest in a race.

Ichinomiya, Takashi

2006-08-01

395

Power  

NASA Technical Reports Server (NTRS)

The space station requires an increase in power or energy of at least several orders of magnitude compared to previous space missions. With the requirement up in the range of 10 kilowatt hours, this obviiously requires the development of new technology. Although the power area is very well integrated in the spacecraft itself, it represents a diverse set of components necessary for energy conversion, electronics, and energy distribution. Considerable work is ongoing at NASA Lewis in the power devices development area, including transformers, large area solid-state chips, transistors, and fast recovery diodes. This work is oriented toward eventual application to both AC and DC power conversion approaches. In the energy storage area, there are many options available to fit into the space station representing various degrees of risk and leverage combination, such as the near-term integral-pressure-vessel nickel hydrogen battery, an advanced Ni-H2 battery concept, and the regenrative hydrogen-oxygen system utilizing essentially the Shuttle orbiter type of fuel cell.

Corbett, R.

1984-01-01

396

Low-cost dielectrics for power distribution transformers  

Microsoft Academic Search

With the continuing improvements in HTS conductors, the application to power distribution transformers becomes possible as well as economical. To realize a viable design, many system aspects must be addressed including the thermal and dielectric characteristics of the winding insulation. This work reports on the study of cellulose-based dielectric insulation and transformer-board for dry-type (conduction cooled), 50 kVA to 5000

Todd Bodziony; Thomas L. Baldwin; Sastry Pamidi; Steinar J. Dale

2005-01-01

397

HIGH-POWER RF DISTRIBUTION SYSTEMFOR THE 8-PACK PROJECT  

SciTech Connect

The 8-Pack Project at SLAC is a prototype rf system whose goal is to demonstrate the high-power X-band technology developed in the NLC/GLC (Next/Global Linear Collider) program. In its first phase, it has reliably produced a 400 ns rf pulse of over 500 MW using a solidstate modulator, four 11.424 GHz klystrons and a dualmoded SLED-II pulse compressor. In Phase 2, the output power of the system has been delivered into the bunker of the NLCTA (Next Linear Collider Test Accelerator) and divided between several accelerator structures for beam acceleration. The authors describe here the design, cold-test measurements, and processing of this power distribution system. Due to the high power levels and the need for efficiency, overmoded waveguide and components are used. For power transport, the TE{sub 01} mode is used in 7.44 cm and 4.064 cm diameter circular waveguide. Only near the structures is standard WR90 rectangular waveguide employed. Components used to manipulate the rf power include transitional tapers, mode converters, overmoded bends, fractional directional couplers, and hybrids.

Nantista, C

2004-08-24

398

An AC Initiation System.  

National Technical Information Service (NTIS)

The patent application relates to initiation systems, and more particularly to an ac initiation system using three ac transmission signals interlocked for safety by frequency, phase and power discrimination. (Author)

M. T. Winton

1978-01-01

399

Validating theoretical hypothesis on access times and repair times statistical distributions for electric power distribution network  

Microsoft Academic Search

Data of interruptions of electric supply in electric power distribution networks and faults of their components were collected by utility company Iberdrola from several Spanish regions. After correcting and mixing these general data for building the histograms of the variables “times to access the faults” and “times to repair” for all data, it can be shown that these two histograms

M. V. Riesco; F. A. Frchoso; P. C. Alvarez; A. Gordaliza

1996-01-01

400

Klystron Cluster Scheme for ILC High Power RF Distribution  

SciTech Connect

We present a concept for powering the main linacs of the International Linear Collider (ILC) by delivering high power RF from the surface via overmoded, low-loss waveguides at widely spaced intervals. The baseline design employs a two-tunnel layout, with klystrons and modulators evenly distributed along a service tunnel running parallel to the accelerator tunnel. This new idea eliminates the need for the service tunnel. It also brings most of the warm heat load to the surface, dramatically reducing the tunnel water cooling and HVAC requirements. In the envisioned configuration, groups of 70 klystrons and modulators are clustered in surface buildings every 2.5 km. Their outputs are combined into two half-meter diameter circular TE{sub 01} mode evacuated waveguides. These are directed via special bends through a deep shaft and along the tunnel, one upstream and one downstream. Each feeds approximately 1.25 km of linac with power tapped off in 10 MW portions at 38 m intervals. The power is extracted through a novel coaxial tap-off (CTO), after which the local distribution is as it would be from a klystron. The tap-off design is also employed in reverse for the initial combining.

Nantista, Christopher; Adolphsen, Chris; /SLAC

2009-07-06

401

Automation of the Athens (Tennessee) electric power distribution system  

SciTech Connect

In an effort to provide electricity at a minimum cost, the electric utility industry continues to examine methods to operate generating plants, transmission lines, distribution equipment, and customer appliances more efficiently. The Athens Automation and Control Experiment (AACE) was conceived and implemented to address these needs. Located on the Athens Utilities Board system in Athens, Tennessee, the AACE is a highly instrumented system serving a closely surveyed group of 2000 consumers. AACE was designed as a test for distribution automation and control experiments. Observation of the results from the experiments will help to show which controls are worthwhile, what data and instrumentation are needed, and which monitoring and control functions for distribution systems are justified. Testing of the new automated system began in the fall of 1985, and the results may have a dramatic impact on the way electric power systems will be designed and operated in the future. Results from volt/var, system reconfiguration, and load control experiments are described.

Gnadt, P.A.

1987-01-01

402

A Power Flow Method for Radial and Meshed Distribution Systems Including Distributed Generation and Step Voltage Regulator Modeling  

Microsoft Academic Search

This paper proposes a new power flow method for radial and meshed distribution systems. The method convert a meshed distribution system with distributed generators into an equivalent single source radial distribution system, by breaking out the tie lines and distributed generators con- nections, and by abstracting auxiliary buses to the distri- bution network. The approach goes beyond the previous works

Diego Issicaba; J. Coelho

2007-01-01

403

A majorization-minimization approach to design of power distribution networks  

SciTech Connect

We consider optimization approaches to design cost-effective electrical networks for power distribution. This involves a trade-off between minimizing the power loss due to resistive heating of the lines and minimizing the construction cost (modeled by a linear cost in the number of lines plus a linear cost on the conductance of each line). We begin with a convex optimization method based on the paper 'Minimizing Effective Resistance of a Graph' [Ghosh, Boyd & Saberi]. However, this does not address the Alternating Current (AC) realm and the combinatorial aspect of adding/removing lines of the network. Hence, we consider a non-convex continuation method that imposes a concave cost of the conductance of each line thereby favoring sparser solutions. By varying a parameter of this penalty we extrapolate from the convex problem (with non-sparse solutions) to the combinatorial problem (with sparse solutions). This is used as a heuristic to find good solutions (local minima) of the non-convex problem. To perform the necessary non-convex optimization steps, we use the majorization-minimization algorithm that performs a sequence of convex optimizations obtained by iteratively linearizing the concave part of the objective. A number of examples are presented which suggest that the overall method is a good heuristic for network design. We also consider how to obtain sparse networks that are still robust against failures of lines and/or generators.

Johnson, Jason K [Los Alamos National Laboratory; Chertkov, Michael [Los Alamos National Laboratory

2010-01-01

404

Soft switched ac-link AC\\/AC and AC\\/DC buck-boost converter  

Microsoft Academic Search

A novel soft switched AC-link buck-boost converter for medium and high power AC-AC and AC-DC applications is proposed. The proposed configuration uses two bi-directional switches per leg of the converter resulting in 12 bi-directional switches for a three-phase to three-phase topology. Power transfer from input to output is accomplished via a link inductor which is first charged from the input

Hamid A. Toliyat; Anand Balakrishnan; Mahshid Amirabadi; William Alexander

2008-01-01

405

Harmonic analysis of multi-phase electric-power distribution systems  

SciTech Connect

This study presents a computer program as a tool for the harmonic analysis of multi-phase electric power distribution systems. In the program, the source of harmonics can be any number of multi-phase harmonic currents and/or voltages, or up to 10 three-phase converts. Frequency-dependent models of ac network elements are assembled into a sparse admittance matrix. Then, sparsity techniques are employed to determine the current flow in all elements and voltages at all busses throughout the system at any harmonic frequency up to 3 KHz. Voltage distortion factors that represent the overall effects of the harmonics of the system voltages are also calculated. The digital program was then applied to a multi-phase distribution system in order to observe the response of the system to the various changes that were made in the system. It was found that the converter size and location, the capacitor bank sizes and locations, and the representation of the system loads are factors in determining in harmonic current flows and the level of voltage-distortion factors. Also, the response of the system to single-phase harmonic sources was investigated, and it was discovered that the effects of single-phase harmonic sources can be serious enough that they should not be ignored in the harmonic analysis of multi-phase systems.

Hosseini, S.H.

1988-01-01

406

Electrical power distribution system based on 1553B bus for advanced aircraft  

Microsoft Academic Search

A novel aeronautical electrical power distribution system based on 1553B bus is proposed in this paper with the analysis of aircraft electrical power distribution system structure. First, several control schemes such as CCS (centralized control system) are researched and the benefit of DCS (distributed control system) configuration is analyzed. Then according to the control flow of aircraft electrical power distribution

Fu Dafeng; Xing Yan; Yang Shanshui; Yan Yangguang

2005-01-01

407

Reactive power compensation capabilities as a function of parasitic components in three-phase AC\\/DC voltage and current source rectifiers  

Microsoft Academic Search

AC\\/DC PWM converters are capable of either supplying or absorbing reactive power while supplying real power to a given load. The operating region is a graphical representation of the range of reactive and active power that these topologies can handle. This paper shows the dependence of the operating region as a function of the parasitic components of the system. Particularly,

J. R. Espinoza; M. A. Perez; Geza Joos; Luis Moran

2001-01-01

408

Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation  

SciTech Connect

This report summarizes the work performed by Hybrid Power Generation Systems, LLC (HPGS) during the April to October 2004 reporting period in Task 2.3 (SOFC Scaleup for Hybrid and Fuel Cell Systems) under Cooperative Agreement DE-FC26-01NT40779 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL), entitled ''Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation''. This study analyzes the performance and economics of power generation systems for central power generation application based on Solid Oxide Fuel Cell (SOFC) technology and fueled by natural gas. The main objective of this task is to develop credible scale up strategies for large solid oxide fuel cell-gas turbine systems. System concepts that integrate a SOFC with a gas turbine were developed and analyzed for plant sizes in excess of 20 MW. A 25 MW plant configuration was selected with projected system efficiency of over 65% and a factory cost of under $400/kW. The plant design is modular and can be scaled to both higher and lower plant power ratings. Technology gaps and required engineering development efforts were identified and evaluated.

David Deangelis; Rich Depuy; Debashis Dey; Georgia Karvountzi; Nguyen Minh; Max Peter; Faress Rahman; Pavel Sokolov; Deliang Yang

2004-09-30

409

Mini-Scale Power Distribution Network Feeding Trapezoidal-Wave Voltages to Power Electronic Loads with Diode Rectifiers  

Microsoft Academic Search

This paper proposes a novel three-phase power distribution system feeding trapezoidal voltages to various power electronic loads with diode rectifier front-ends. The network distributes trapezoidal voltages generated by synchronous superposition of wave-shaping voltages onto sinusoidal voltages available from a utility power grid. The power distribution by the trapezoidal voltages allows reducing harmonics of the line currents without electronic switching devices

Toshihiko Noguchi; Masaru Imoto; Yoshikazu Sato

2004-01-01

410

Application of power electronics to the distribution transformer  

NASA Astrophysics Data System (ADS)

This dissertation describes the design and prototype construction of a novel Solid State Transformer (SST). Conventional distribution transformers are in many ways relics of turn-of-the-century technology. While efficient and inexpensive, their secondary voltage waveforms are tightly coupled to the applied primary voltage waveforms, and primary currents are dictated by the load currents. This can cause power quality problems for both the source and the load. Conventional distribution transformers also have inherent voltage drop which increases with load. Replacement of conventional distribution transformers with solid-state devices could provide control over the magnitudes and waveforms of the load voltage and input current. Self-protection would be a natural byproduct of the controls. At the same time, a solid-state transformer would perform all the functions of conventional devices. Previous efforts to develop a solid-state transformer, including one recently sponsored by the Electric Power Research Institute (EPRI), have been limited and comparatively crude demonstration projects. They did not provide isolation and have proven to be impractical when applied to utility distribution voltage levels. These efforts did, however, provide the level of interest sufficient to encourage design of the practical solid-state transformer described herein and eventual construction of a prototype. In this dissertation, an SST architecture is set forth that is specifically designed to operate at utility distribution voltages. It provides a sinusoidal secondary voltage regardless of the primary voltage waveform, provides a secondary voltage magnitude that is independent of either load current or primary voltage magnitude, and at the same time draws sinusoidal input current which is in phase with the primary voltage regardless of secondary current or primary voltage waveshapes.

Ronan, Edward Robert, Jr.

411

Packaging and power distribution design considerations for a Sun Microsystems desktop workstation  

Microsoft Academic Search

The power distribution system will become an increasingly important package design consideration for computer systems such as the Sun Microsystems desktop workstation, at least as important as simultaneous switch. Power distribution impedance is controlled by the switching power supply, bulk capacitance, ceramic capacitance and power plane properties at various portions of the frequency spectrum. A major concern with package power

Larry D Smith

1997-01-01

412

Life cycle assessment of overhead and underground primary power distribution.  

PubMed

Electrical power can be distributed in overhead or underground systems, both of which generate a variety of environmental impacts at all stages of their life cycles. While there is considerable literature discussing the trade-offs between both systems in terms of aesthetics, safety, cost, and reliability, environmental assessments are relatively rare and limited to power cable production and end-of-life management. This paper assesses environmental impacts from overhead and underground medium voltage power distribution systems as they are currently built and managed by Southern California Edison (SCE). It uses process-based life cycle assessment (LCA) according to ISO 14044 (2006) and SCE-specific primary data to the extent possible. Potential environmental impacts have been calculated using a wide range of midpoint indicators, and robustness of the results has been investigated through sensitivity analysis of the most uncertain and potentially significant parameters. The studied underground system has higher environmental impacts in all indicators and for all parameter values, mostly due to its higher material intensity. For both systems and all indicators the majority of impact occurs during cable production. Promising strategies for impact reduction are thus cable failure rate reduction for overhead and cable lifetime extension for underground systems. PMID:20553042

Bumby, Sarah; Druzhinina, Ekaterina; Feraldi, Rebe; Werthmann, Danae; Geyer, Roland; Sahl, Jack

2010-07-15

413

Power-law distributions from additive preferential redistributions  

NASA Astrophysics Data System (ADS)

We introduce a nongrowth model that generates the power-law distribution with the Zipf exponent. There are N elements, each of which is characterized by a quantity, and at each time step these quantities are redistributed through binary random interactions with a simple additive preferential rule, while the sum of quantities is conserved. The situation described by this model is similar to those of closed N -particle systems when conservative two-body collisions are only allowed. We obtain stationary distributions of these quantities both analytically and numerically while varying parameters of the model, and find that the model exhibits the scaling behavior for some parameter ranges. Unlike well-known growth models, this alternative mechanism generates the power-law distribution when the growth is not expected and the dynamics of the system is based on interactions between elements. This model can be applied to some examples such as personal wealths, city sizes, and the generation of scale-free networks when only rewiring is allowed.

Ree, Suhan

2006-02-01

414

Tomographic determination of the power distribution in electron beams  

DOEpatents

A tomographic technique for determining the power distribution of an electron beam using electron beam profile data acquired from a modified Faraday cup to create an image of the current density in high and low power beams is disclosed. A refractory metal disk with a number of radially extending slits is placed above a Faraday cup. The beam is swept in a circular pattern so that its path crosses each slit in a perpendicular manner, thus acquiring all the data needed for a reconstruction in one circular sweep. Also, a single computer is used to generate the signals actuating the sweep, to acquire that data, and to do the reconstruction, thus reducing the time and equipment necessary to complete the process. 4 figs.

Teruya, A.T.; Elmer, J.W.

1996-12-10

415

Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation  

SciTech Connect

This report summarizes the work performed by Hybrid Power Generation Systems, LLC during the October 2002 to December 2002 reporting period under Cooperative Agreement DE-FC26-01NT40779 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation''. The main objective of this project is to develop and demonstrate the feasibility of a highly efficient hybrid system integrating a planar Solid Oxide Fuel Cell (SOFC) and a turbogenerator. The following activities have been carried out during this reporting period: {lg_bullet} Conceptual system design trade studies were performed {lg_bullet} Part-load performance analysis was conducted {lg_bullet} Primary system concept was down-selected {lg_bullet} Dynamic control model has been developed {lg_bullet} Preliminary heat exchanger designs were prepared {lg_bullet} Pressurized SOFC endurance testing was performed

Nguyen Minh; Faress Rahman

2002-12-31

416

Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation  

SciTech Connect

This report summarizes the work performed by Hybrid Power Generation Systems, LLC (HPGS) during the January to June 2004 reporting period under Cooperative Agreement DE-FC26-01NT40779 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation''. The main objective of this project is to develop and demonstrate the feasibility of a highly efficient hybrid system integrating a planar Solid Oxide Fuel Cell (SOFC) and a micro-turbine. In addition, an activity included in this program focuses on the development of an integrated coal gasification fuel cell system concept based on planar SOFC technology. Also, another activity included in this program focuses on the development of SOFC scale up strategies.

Nguyen Minh

2004-07-04

417

Power Scheduling for a Network of Distributed Generators  

NASA Astrophysics Data System (ADS)

Growing concerns over the economic and environmental costs of fossil fuels have spurred renewed interest in the area of renewable energy. The Atlantic Sustainable Power Research Initiative (ASPRI) aims to integrate low- and no-emission technology into Atlantic Canada's energy generation mix. This research focuses on the scheduling of distributed generators to improve their aggregate performance while maintaining a small ecological footprint. Combining renewable units with low-emission units using conventional fuels promises improved profitability and reliability over any single technology. Four Unit Commitment methods have been considered for the Energy Control Center (ECC), one of them novel. The novel solution appears to be the first to successfully solve the static Unit Commitment problem in less than exponential time with respect to the number of units - this is especially important when incorporating numerous distributed generators. The stochastic Unit Commitment problem is also considered in an effort to maximize the advantages of intermittent, renewable generators.

Dupuis, Etienne Jacques

418

Automated fault location and diagnosis on electric power distribution feeders  

SciTech Connect

This paper presents new techniques for locating and diagnosing faults on electric power distribution feeders. The proposed fault location and diagnosis scheme is capable of accurately identifying the location of a fault upon its occurrence, based on the integration of information available from disturbance recording devices with knowledge contained in a distribution feeder database. The developed fault location and diagnosis system can also be applied to the investigation of temporary faults that may not result in a blown fuse. The proposed fault location algorithm is based on the steady-state analysis of the faulted distribution network. To deal with the uncertainties inherent in the system modeling and the phasor estimation, the fault location algorithm has been adapted to estimate fault regions based on probabilistic modeling and analysis. Since the distribution feeder is a radial network, multiple possibilities of fault locations could be computed with measurements available only at the substation. To identify the actual fault location, a fault diagnosis algorithm has been developed to prune down and rank the possible fault locations by integrating the available pieces of evidence. Testing of the developed fault location and diagnosis system using field data has demonstrated its potential for practical use.

Zhu, J. [Advanced Control Systems, Inc., Norcross, GA (United States); Lubkeman, D.L.; Girgis, A.A. [Clemson Univ., SC (United States). Dept. of Electrical and Computer Engineering

1997-04-01

419

Fish Method: Interaction between AC-Machines and Switching Power Converters.  

National Technical Information Service (NTIS)

When studying the complex interaction between AC-machines and converters, proper simulation models are necessary. This thesis is devoted to a new viewpoint on this complex matter: the Fish Method. Based on a seemingly reckless simplification of the machin...

A. Veltman

1994-01-01

420

A universal active power filter for single-phase reactive power and harmonic compensation  

Microsoft Academic Search

In modern power distribution systems, the majority of loads draw reactive power and\\/or harmonic currents from the AC source along with main active power currents. These nonunity power factor linear and nonlinear loads cause low efficiency of the power supply system, poor power factor, destruction of other equipment due to excessive stresses and EMI problems. Active filters have been considered

Bhim Singh; Kamal Al-Haddad; Ambrish Chandra

1998-01-01

421

Autonomous adaptive agents for distributed control of the electric power grid in a competitive electric power industry  

Microsoft Academic Search

A generic model of a complete electric power grid (including generation, transmission, distribution and loads), based on multiple adaptive, intelligent agents, is being developed by the Electric Power Research Institute (EPRT). Its ultimate purpose is to model the computational intelligence required for distributed control of a geographically dispersed but globally interconnected power network. The current worldwide trend toward free competition

A. Martin Wildberger

1997-01-01

422

Modified One-Cycle Controlled Bidirectional High-Power-Factor AC-to-DC Converter  

Microsoft Academic Search

AC-to-DC converters based on one-cycle control exhibit instability in current control at light load conditions as well as when they are operating in the inverting mode. In this paper, a modified one-cycle controller for bidirectional AC-to-DC converter is proposed. A fictitious current component in phase with the utility voltage is synthesized. The sum of this current component and the actual

Dharmraj V. Ghodke; Kishore Chatterjee; B. G. Fernandes

2008-01-01

423

Advanced building blocks of power converters for renewable energy based distributed generators  

Microsoft Academic Search

The power converter is a critical component of a distributed generation (DG) system, particularly for a renewable energy based distributed generator. With the rapid development and growing applications of DG systems, power converters have evolved from a traditional \\

Riming Shao; Mary Kaye; Liuchen Chang

2011-01-01

424

Splitting and paralleling research of the distribution system which contain distributed generation (DG) under the power system faults  

Microsoft Academic Search

With the using of the renewable sources increasingly, application of the distributed generation (DG) in the distribution system acquired more attention. After the power system faults, distribution system which contains many DGs would usually cut off the DGs from the distribution system at the joint where the DGs connected into the system term less. However, considering the enlarge scale and

Sun Ming; Wang Lei; Wang Zhi-Guo

2008-01-01

425

Study of the longitudinal distribution of power generated in a random distributed feedback Raman fibre laser with unidirectional pumping  

SciTech Connect

The longitudinal distribution of the Stokes-component power in a Raman fibre laser with a random distributed feedback and unidirectional pumping is measured. The fibre parameters (linear loss and Rayleigh backscattering coefficient) are calculated based on the distributions obtained. A numerical model is developed to describe the lasing power distribution. The simulation results are in good agreement with the experimental data. (optical fibres, lasers and amplifiers. properties and applications)

Churkin, D V; El-Taher, A E; Vatnik, I D; Babin, Sergei A

2012-09-30

426

HV AC generation based on resonant circuits with variable frequency for testing of electrical power equipment on site  

Microsoft Academic Search

The overall booming industry has great need for electrical industry. Hence, electrical power generation, transmission and distribution have to respond to the continuously growing demand by e.g. increased transmission capacities or trans-mission voltages but also by longer transmission networks. Hereby, the more and more demanding requirements for devices of power transmission and distribution have to be fulfilled by the high

S. Schierig; T. Steiner; M. Jochim

2008-01-01

427

Distributed Power Control with Multiple Agents in a Distributed Base Station Scheme Using Macrodiversity  

NASA Astrophysics Data System (ADS)

Power management in wireless networks has been thoroughly studied and applied in many different contexts. However, the problem has not been tackled from a multiple-agent perspective (MA). This paper intends to do so in the context of a wireless network comprised of distributed base stations using macrodiversity. The proposed design is shown to provide efficient use of macrodiversity resources and high energy efficiency when compared with more traditional algorithms. Moreover, the power control mechanism is completely decentralized, while avoiding direct information exchange or excessive signaling, which makes it highly scalable. Its auto-configuration property, stemming from its MA basis, offers high adaptivity when experiencing high or low interference levels. This leads to a naturally balanced resource usage, while also maintaining nearly full efficiency with only a reduced set of discrete power levels, thus making low-cost electronic implementation practical.

Leroux, Philippe; Roy, Sébastien

428

Power Law Distributions of Patents as Indicators of Innovation  

NASA Astrophysics Data System (ADS)

The total number of patents produced by a country (or the number of patents produced per capita) is often used as an indicator for innovation. Such figures however give an overly simplistic measure of innovation within a country. Here we present evidence that the distribution of patents amongst applicants within many countries is well-fitted to a power law distribution with exponents that vary between 1.66 (Japan) and 2.37 (Poland). We suggest that this exponent is a useful new metric for studying innovation. Using simulations based on simple preferential attachment-type rules that generate power laws, we find we can explain some of the variation in exponents between countries, with countries that have larger numbers of patents per applicant generally exhibiting smaller exponents in both the simulated and actual data. Similarly we find that the exponents for most countries are inversely correlated with other indicators of innovation, such as research and development intensity or the ubiquity of export baskets. This suggests that in more advanced economies, which tend to have smaller values of the exponent, a greater proportion of the total number of patents are filed by large companies than in less advanced countries.

O'Neale, Dion; Hendy, Shaun

2013-03-01

429

Implementation and control of grid connected AC-DC-AC power converter for variable speed wind energy conversion system  

Microsoft Academic Search

30 kW electrical power conversion system is developed for a variable speed wind turbine system. In the wind energy conversion system (WECS) a synchronous generator converts the mechanical energy into electrical energy. As the voltage and frequency of generator output vary along the wind speed change, a DC-DC boosting chopper is utilized to maintain constant DC link voltage. The input

Seung-Ho Song; Shin-il Kang; Nyeon-kun Hahm

2003-01-01

430

Power distribution, the environment, and public health: A state-level analysis  

Microsoft Academic Search

This paper examines relationships among power distribution, the environment, and public health by means of a cross-sectional analysis of the 50 US states. A measure of inter-state variations in power distribution is derived from data on voter participation, tax fairness, Medicaid access, and educational attainment. We develop and estimate a recursive model linking the distribution of power to environmental policy,

James K. Boyce; Andrew R. Klemer; Paul H. Templet; Cleve E. Willis

1999-01-01

431

The integration of renewable energy sources into electric power distribution systems. Volume 1: National assessment  

Microsoft Academic Search

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

P. R. Barnes; J. W. Vandyke; F. M. Tesche; H. W. Zaininger

1994-01-01

432

Radiation Effects on Power Semiconductor Devices for Distributed Power Systems for Electromagnetic Calorimeters  

NASA Astrophysics Data System (ADS)

The present study faces the radiation tolerance aspect for two main device categories typically used for power supplies of electromagnetic calorimeters for high-energy physics, like ATLAS Liquid-Ar calorimeters: 200V-MOSFETs and 30V-MOSFETs, which are fundamental for manipulating the primary voltage and the secondary voltage, respectively, of the power distribution system. Results demonstrate that the gate driving policy can significantly affect the radiation tolerance of such devices, suggesting a promising method to reach the 1Mrad target.

Abbate, C.; Busatto, G.; Iannuzzo, F.; Porzio, A.; Sanseverino, A.; Velardi, F.; Baccaro, S.

2010-04-01

433

Application of pulse doubling in delta\\/polygon-connected transformer-based 36-pulse ac-dc converter for power quality improvement  

Microsoft Academic Search

This paper presents a pulse doubling technique in a 36-pulse ac-dc converter which supplies direct torque-controlled motor drives (DTCIMD's) in order to have better power quality conditions at the point of common coupling. The proposed technique increases the number of rectification pulses without significant changes in the installations and yields in harmonic reduction in both ac and dc sides. The

Rohollah Abdollahi; Alireza Jalilian

2012-01-01

434

Distributed optimal power and rate control in wireless sensor networks.  

PubMed

With the rapid development of wireless sensor networks, reducing energy consumption is becoming one of the important factors to extend node lifetime, and it is necessary to adjust the launching power of each node because of the limited energy available to the sensor nodes in the networks. This paper proposes a power and rate control model based on the network utility maximization (NUM) framework, where a weighting factor is used to reflect the influence degree of the sending power and transmission rate to the utility function. In real networks, nodes interfere with each other in the procedure of transmitting signal, which may lead to signal transmission failure and may negatively have impacts on networks throughput. Using dual decomposition techniques, the NUM problem is decomposed into two distributed subproblems, and then the conjugate gradient method is applied to solve the optimization problem with the calculation of the Hessian matrix and its inverse in order to guarantee fast convergence of the algorithm. The convergence proof is also provided in this paper. Numerical examples show that the proposed solution achieves significant throughput compared with exiting approaches. PMID:24895654

Tang, Meiqin; Bai, Jianyong; Li, Jing; Xin, Yalin

2014-01-01

435

Distributed Optimal Power and Rate Control in Wireless Sensor Networks  

PubMed Central

With the rapid development of wireless sensor networks, reducing energy consumption is becoming one of the important factors to extend node lifetime, and it is necessary to adjust the launching power of each node because of the limited energy available to the sensor nodes in the networks. This paper proposes a power and rate control model based on the network utility maximization (NUM) framework, where a weighting factor is used to reflect the influence degree of the sending power and transmission rate to the utility function. In real networks, nodes interfere with each other in the procedure of transmitting signal, which may lead to signal transmission failure and may negatively have impacts on networks throughput. Using dual decomposition techniques, the NUM problem is decomposed into two distributed subproblems, and then the conjugate gradient method is applied to solve the optimization problem with the calculation of the Hessian matrix and its inverse in order to guarantee fast convergence of the algorithm. The convergence proof is also provided in this paper. Numerical examples show that the proposed solution achieves significant throughput compared with exiting approaches.

Tang, Meiqin; Bai, Jianyong; Li, Jing; Xin, Yalin

2014-01-01

436

ACS imaging of star clusters in M 51. I. Identification and radius distribution  

Microsoft Academic Search

Context: Size measurements of young star clusters are valuable tools to put constraints on the formation and early dynamical evolution of star clusters. Aims: We use HST\\/ACS observations of the spiral galaxy M 51 in F435W, F555W and F814W to select a large sample of star clusters with accurate effective radius measurements in an area covering the complete disc of

R. A. Scheepmaker; M. R. Haas; M. Gieles; N. Bastian; S. S. Larsen

2007-01-01

437

An attractive new converter topology for AC\\/DC, DC\\/DC & DC\\/AC power conversion  

Microsoft Academic Search

A new power converter topology is proposed. The new converter is essentially a four-quadrant converter offering several advantages. These include high efficiency, reduced size and weight, excellent dynamic performance, and inherent galvanic isolation. The new topology proposed has the potential for a wide range of applications such as: inverters, rectifiers, and step-up step-down four quadrant converters for special applications. The

G. Cimador; P. Prestifilippo

1990-01-01

438

Reactive power compensation and load balancing in electric power distribution systems  

Microsoft Academic Search

This article presents a new method for reactive power compensation and load balancing in a four-wire, three-phase distribution system. An IGBT-based PWM voltage source inverter with a dc bus capacitor is used as a compensator. The hysteresis-based carrierless PWM current control is employed to derive switching signals to the devices of the compensator. A detailed dynamic model of the complete

Bhim Singh; Ambrish Chandra; Kamal Al-Haddad; Anuradha; D. P. Kothari

1998-01-01

439

A Study on Collaborative Operation Method for a New Energy Type Dispersed Power Supply System by AC-EMAP Model  

NASA Astrophysics Data System (ADS)

Application of a dispersed power supply system combined with a large scale photovoltaic system (PV), a fuel cell (FC) and an electric double layer capacitor (EDLC) is studied in this paper. This system is operated in autonomous mode, taking account of time delay characteristics of FC. The modified Euler type Moving Average Prediction (EMAP) model is improved using short time fast fourier transform (ST-FFT). The Adaptive Control type EMAP (AC-EMAP) model is introduced to reduce the capacity of EDLC. This system can meet the multi-quality electric power requirements of customers, and compensate voltage stability and uninterruptible power supply (UPS) function as well. Moreover, the required capacity of EDLC to compensate the fluctuation of both PV output and load demand is clarified by the simulation based on collaborative operation method by a prediction model using software MATLAB/Simulink.

Hidese, Koichi; Takano, Ichiro; Nishikawa, Hisao; Sawada, Yoshio

440

Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation  

SciTech Connect

This report summarizes the work performed by Honeywell during the January 2002 to March 2002 reporting period under Cooperative Agreement DE-FC26-01NT40779 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation''. The main objective of this project is to develop and demonstrate the feasibility of a highly efficient hybrid system integrating a planar Solid Oxide Fuel Cell (SOFC) and a turbogenerator. For this reporting period the following activities have been carried out: {lg_bullet} Conceptual system design trade studies were performed {lg_bullet} System-level performance model was created {lg_bullet} Dynamic control models are being developed {lg_bullet} Mechanical properties of candidate heat exchanger materials were investigated {lg_bullet} SOFC performance mapping as a function of flow rate and pressure was completed

Nguyen Minh

2002-03-31

441

SOLID OXIDE FUEL CELL HYBRID SYSTEM FOR DISTRIBUTED POWER GENERATION  

SciTech Connect

This report summarizes the work performed by Honeywell during the October 2001 to December 2001 reporting period under Cooperative Agreement DE-FC26-01NT40779 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation''. The main objective of this project is to develop and demonstrate the feasibility of a highly efficient hybrid system integrating a planar Solid Oxide Fuel Cell (SOFC) and a turbogenerator. The conceptual and demonstration system designs were proposed and analyzed, and these systems have been modeled in Aspen Plus. Work has also started on the assembly of dynamic component models and the development of the top-level controls requirements for the system. SOFC stacks have been fabricated and performance mapping initiated.

Kurt Montgomery; Nguyen Minh

2003-08-01

442

SOLID OXIDE FUEL CELL HYBRID SYSTEM FOR DISTRIBUTED POWER GENERATION  

SciTech Connect

This report summarizes the work performed by Honeywell during the July 2001 to September 2001 reporting period under Cooperative Agreement DE-FC26-01NT40779 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation''. The main objective of this project is to develop and demonstrate the feasibility of a highly efficient hybrid system integrating a planar Solid Oxide Fuel Cell (SOFC) and a turbogenerator. An internal program kickoff was held at Honeywell in Torrance, CA. The program structure was outlined and the overall technical approach for the program was presented to the team members. Detail program schedules were developed and detailed objectives were defined. Initial work has begun on the system design and pressurized SOFC operation.

Unknown

2002-03-01

443

Power Law Distributions of Patents as Indicators of Innovation  

PubMed Central

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.

O'Neale, Dion R. J.; Hendy, Shaun C.

2012-01-01

444

MHD-EMP interaction with power transmission and distribution systems  

SciTech Connect

A nuclear detonation at altitudes of several hundred kilometers above the earth will distort the earth's magnetic field and results in a time-variation of the geomagnetic field on the earth's surface. This magnetic field interacts with the finitely conducting earth to produce a time varying electric field, also on the earth's surface. Known at the magnetohydrodynamic electromagnetic pulse (MHD-EMP), this resulting E-field can induce a net voltage in long electrical conductors, such as power transmission lines. If these conductors are electrically connected to the earth at both ends, a current can be induced to flow in the conductors, and this can cause damage or upset to certain electrical systems. This paper presents the results of a study on the interaction of the MHD-EMP with power transmission and distribution (T D) systems. A brief overview of the MHD-EMP environment used in the study is presented, and the analytical models used for estimating the coupling of this environment to T D lines are discussed. Because of the quasi-static nature of MHD-EMP, the models are essentially simple DC circuit models. However, complications arise in attempting to treat realistic line configurations having a large number of support towers and an overhead shield or neutral wires. There models are discussed in detail. 3 refs., 5 figs., 1 tab.

Tesche, F.M. (Tesche (F.M.), Dallas, TX (United States)); Barnes, P.R. (Oak Ridge National Lab., TN (United States))

1991-01-01

445

MHD-EMP interaction with power transmission and distribution systems  

SciTech Connect

A nuclear detonation at altitudes of several hundred kilometers above the earth will distort the earth`s magnetic field and results in a time-variation of the geomagnetic field on the earth`s surface. This magnetic field interacts with the finitely conducting earth to produce a time varying electric field, also on the earth`s surface. Known at the magnetohydrodynamic electromagnetic pulse (MHD-EMP), this resulting E-field can induce a net voltage in long electrical conductors, such as power transmission lines. If these conductors are electrically connected to the earth at both ends, a current can be induced to flow in the conductors, and this can cause damage or upset to certain electrical systems. This paper presents the results of a study on the interaction of the MHD-EMP with power transmission and distribution (T&D) systems. A brief overview of the MHD-EMP environment used in the study is presented, and the analytical models used for estimating the coupling of this environment to T&D lines are discussed. Because of the quasi-static nature of MHD-EMP, the models are essentially simple DC circuit models. However, complications arise in attempting to treat realistic line configurations having a large number of support towers and an overhead shield or neutral wires. There models are discussed in detail. 3 refs., 5 figs., 1 tab.

Tesche, F.M. [Tesche (F.M.), Dallas, TX (United States); Barnes, P.R. [Oak Ridge National Lab., TN (United States)

1991-12-01

446

Mathematical Model for the DC-AC Inverter for the Space Shuttle.  

National Technical Information Service (NTIS)

The reader is informed of what was done for the mathematical modeling of the dc-ac inverter for the Space Shuttle. The mathematical modeling of the dc-ac inverter is an essential element in the modeling of the electrical power distribution system of the S...

F. C. Berry

1987-01-01

447

ACS imaging of star clusters in M 51 : I. Identification and radius distribution  

Microsoft Academic Search

Context. Size measurements of young star clusters are valuable tools to put constraints on the formation and early dynamical evolution\\u000aof star clusters.\\u000aAims. We use HST\\/ACS observations of the spiral galaxy M51 in F435W, F555W and F814W to select a large sample of star clusters\\u000awith accurate effective radius measurements in an area covering the complete disc ofM51.We present

R. A. Scheepmaker; M. R. Haas; M. Gieles; N. Bastian; S. S. Larsen

2007-01-01

448

Fuel cell distributed power package unit. Final report  

SciTech Connect

Energy and Environmental Research Corporation (EER) has completed phase 1 of a three-phase program to design, develop, and demonstrate an integrated prototype system for generating electric power for buildings. The DOE program objectives for the fuel processor system include: operation with natural gas; hydrogen suitable for PEM fuel cells in the 25 to 100 kW range; operation with system level efficiency of at least 35% (for electricity production) based on the higher heating value (HHV) of natural gas, installed system cost of $1,500 per kW, with the fuel processor cost at $350 per kW or less, for production levels as low as 5,000 units/year, and operational life of 5 years or more and minimal maintenance requirements. This report presents some relevant background information on distributed power generation (DPG) and the role of fuel cell systems with cogeneration in expanding that market. A description of the proposed integrated prototype system and the computer models developed to aid in system evaluation is then provided, along with a discussion of the operational efficiency of the system. Next, the details of design and operation of the breadboard system are described. This is followed with a preliminary commercial feasibility of EER`s power system for applications in a variety of markets both domestic and foreign. The commercial feasibility assessment presents the short to long-term market potential, the technical feasibility in terms of economics, mechanics and market drivers and finally presents two economic case studies for UMR applied to a small motel and a residential complex. Finally, a summary of the performance for the proposed DPG system is presented. It is the objective of this report to present details on the extent to which EER`s fuel processor meets the DOE program objectives.

Not Available

1998-12-24

449

Connection between dispersed power sources and utility distribution systems: TEPCO's technical challenges  

Microsoft Academic Search

The use of dispersed power sources is spreading, including renewable sources such as solar and wind power. Increasingly, utilities in Japan are seeking to connect these sources within their distribution systems. However, uncontrolled or nonregulated connections to these power sources may compromise the supply reliability, quality of utility power, and even public safety. To promote the spread of dispersed power

S. Odagiri

2002-01-01

450

Design of a power management and distribution system for a thermionic-diode powered spacecraft  

NASA Technical Reports Server (NTRS)

The Electrical Systems Development Branch of the Power Technology Division at the NASA Lewis Research Center in Cleveland, Ohio is designing a Power Management and Distribution (PMAD) System for the Air Force's Integrated Solar Upper Stage (ISUS) Engine Ground Test Demonstration (EGD). The ISUS program uses solar-thermal propulsion to perform orbit transfers from Low Earth Orbit (LEO) to Geosynchronous Orbit (GEO) and from LEO to Molnya. The ISUS uses the same energy conversion receiver to perform the LEO to High Earth Orbit (HEO) transfer and to generate on-orbit electric power for the payloads. On-orbit power generation is accomplished via two solar concentrators heating a dual-cavity graphite-core which has Thermionic Diodes (TMD's) encircling each cavity. The graphite core and concentrators together are called the Receiver and Concentrator (RAC). The TDM-emitters reach peak temperatures of approximately 2200K, and the TID-collectors are run at approximately 1000K. Because of the high Specific Impulse (I(sup sp)) of solar thermal propulsion relative to chemical propulsion, and because a common bus is used for communications, GN&C, power, etc., a substantial increase in payload weight is possible. This potentially allows for a stepdown in the required launch vehicle size or class for similar payload weight using conventional chemical propulsion and a separate spacecraft bus. The ISUS power system is to provide 1000W(sub e) at 28+/-6V(sub dc) to the payload/spacecraft from a maximum TID generation capability of 1070W(sub e) at 2200K. Producing power with this quality, protecting the spacecraft from electrical faults and accommodating operational constraints of the TID's are the responsibilities of the PMAD system. The design strategy and system options examined along with the proposed designs for the Flight and EGD configurations are discussed herein.

Kimnach, Greg L.

1996-01-01

451

Improvements in Power Quality and Efficiency with a new AC\\/DC High Current Converter  

Microsoft Academic Search

A bstract: - A very flexible AC\\/DC converter featuring high-output current, reduced voltage ripple and highly adjustable current control is described. The whole system consists of four stages and uses a proper switching technique in conjunction with a feedback control performed by means of a PID regulator. Moreover, the built prototype exhibits high efficiency and reduced harmonic pollution. In order

F RANCESCO MUZI; LUIGI PASSACANTANDO; Francesco Muzi

2008-01-01

452

Theory of the Brush-Shifting AC Motor ? IV Speed Control With Power-Factor Correction  

Microsoft Academic Search

The preceding papers of this series presented an analysis of the brush-shifting a-c motor. Parts I and II dealt with the case when the voltage introduced into the stator coils from the commutator was collinear with the voltage induced in the stator coils by slip. Part III dealt with the case when the voltage introduced into the stator coils from

A. G. Conrad; F. Zweig; J. G. Clarke

1942-01-01

453

Multi-infeed HVDC\\/AC power system modeling and analysis with dynamic phasor application  

Microsoft Academic Search

In this paper, dynamic phasor method has been applied to HVDC transmission system and FACTS device modeling. A hybrid-model simulation algorithm is suggested for transient stability analysis with HVDC transmission system and FACTS devices in dynamic phasor models and other AC system elements in electromechanical models. Computer test results show clearly that the proposed hybrid-model simulation algorithm can be applied

Haojun Zhu; Zexiang Cai; Haoming Liu; Yixin Ni

2005-01-01

454

Two issues in the municipal ownership of electric power distribution systems. [Statistical\\/econometric scrutiny  

Microsoft Academic Search

Though municipal ownership of electric power distribution systems has been a growing public issue since the late 1960s, serious empirical econometric investigation of distribution has barely begun. The author opens with a critique of two recent works on distribution costs: one on distribution return to scale and one on comparative public\\/private efficiency. A new conceptualization of the factors influencing distribution

Neuberg

2009-01-01

455

AC over-current test results of YBCO conductor for YBCO power transformer with fault current limiting function  

NASA Astrophysics Data System (ADS)

We are developing elemental technology for 66 kV/6.9 kV 20 MVA-class YBCO power transformer. The YBCO transformer is considered to have a possibility to stabilize the power system by improving function of fault current limiting. Current limiting behavior functions over critical current flows. There is a possibility that superconducting characteristic may be damaged due to increase in temperature of YBCO tapes. Therefore, we have taken a measure to combine YBCO tape with CuNi tape or Cu Tape. We manufactured model coils using these conductors and conducted the AC over-current tests. The test current was two to seven times larger than the Ic of conductor and it was damped with time from its maximum value according to the generation of conductor resistance. We verified the effectiveness of current limiting characteristics. In these tests, the Ic of model coil did not degrade. We consider this conductor to be able to withstand AC over-current with the function of current limiting.

Tomioka, A.; Otonari, T.; Ogata, T.; Iwakuma, M.; Okamoto, H.; Hayashi, H.; Iijima, Y.; Saito, T.; Gosho, Y.; Tanabe, K.; Izumi, T.; Shiohara, Y.

2011-11-01

456

Validating MCNP for LEU Fuel Design via Power Distribution Comparisons  

SciTech Connect

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 experimental and calculated values for both conditions were within the reported experimental uncertainties except for some of the foils located on the top and bottom edges of the fuel plates.

Primm, Trent [ORNL; Maldonado, G Ivan [ORNL; Chandler, David [ORNL

2008-11-01

457

Development of a hardware-based AC microgrid for AC stability assessment  

NASA Astrophysics Data System (ADS)

As more power electronic-based devices enable the development of high-bandwidth AC microgrids, the topic of microgrid power distribution stability has become of increased interest. Recently, researchers have proposed a relatively straightforward method to assess the stability of AC systems based upon the time-constants of sources, the net bus capacitance, and the rate limits of sources. In this research, a focus has been to develop a hardware test system to evaluate AC system stability. As a first step, a time domain model of a two converter microgrid was established in which a three phase inverter acts as a power source and an active rectifier serves as an adjustable constant power AC load. The constant power load can be utilized to create rapid power flow transients to the generating system. As a second step, the inverter and active rectifier were designed using a Smart Power Module IGBT for switching and an embedded microcontroller as a processor for algorithm implementation. The inverter and active rectifier were designed to operate simultaneously using a synchronization signal to ensure each respective local controller operates in a common reference frame. Finally, the physical system was created and initial testing performed to validate the hardware functionality as a variable amplitude and variable frequency AC system.

Swanson, Robert R.

458

Aging Management Guideline for commercial nuclear power plants: Power and distribution transformers  

SciTech Connect

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.

Toman, G.; Gazdzinski, R. [Sandia National Labs., Albuquerque, NM (United States)

1994-05-01

459

Computer analysis of harmonic distortion in electrical-power-distribution systems. Master's thesis  

Microsoft Academic Search

The number of nonlinear loads connected to power distribution systems is rapidly increasing. These loads disturb the sinusoidal nature of the power distribution systems to which they are connected. Consequently, all connected loads may be affected by even a single nonlinear load. This makes power quality an increasingly important issue, particularly in shipboard applications because equipment malfunction can cause the

Gedo

1991-01-01

460

Time-varying failure rate extraction in electric power distribution equipment  

Microsoft Academic Search

Reliability evaluation of power distribution system is very important to both power utilities and customers. It presents the probabilistic number and duration of interruption such as failure rate, SAIDI, SAIFI, and CAIDI. However, it has a fatal weakness at reliability index because of accuracy of failure rate. In this paper, the time-varying failure rate (TFR) of power distribution system equipment

Jong-Fil Moon; Jea-Chul Kim; Hee-Tae Lee; Sang-Seung Lee; Yong Tae Yoon; Kyung-Bin Song

2006-01-01

461

A Integrated Power Flow Algorithm for Radial Distribution System with DGs Based on Voltage Regulating  

Microsoft Academic Search

It proposes a promising power flow analysis method for radial distribution system with distributed generations (DGs), combined with reactive power compensation facilities. In the power flow analysis, suitable models are determined for different DG units, Q-sources including Static Var Compensator, Switched Capacitor or Shunt Capacitor and Step Voltage Regulator. A helpful method is presented to deal with the PV node,

Liu Qingzhen; Cai Jinding

2010-01-01

462

Recent research and development on power systems with a large number of distributed generating facilities  

Microsoft Academic Search

The paper describes the achievements and trend in research and development in Japan related to power system connections of a large number of distributed generation (DG). The major results from some of the R&D projects related to power system connections of PV or wind power generations are presented. In addition, current research activities for new technologies for distributing and managing

T. Ichikawa

2002-01-01

463

Transient stability evaluation of power systems with large amounts of distributed generation  

Microsoft Academic Search

It is expected that increasing amount of distributed generation (DG) will be connected to electrical power systems in the near future. When these generations are in small amounts, their impacts on power system dynamics will be negligible. But if the penetration level becomes higher, distributed generations may start to influence the dynamic behavior of a power system as a whole

A. Khosravi; M. Jazaeri; S. A. Mousavi

2010-01-01

464

An assessment of reactive power\\/voltage control devices in distribution networks  

Microsoft Academic Search

This paper provides an assessment of candidate voltage\\/reactive power control devices for distribution systems. The recent trend toward distributed energy resources (DERs), and distributed generation (DG), in particular, is often based on the rationale to support voltage and compensate for reactive power closer to the end users. This situation calls for a systematic approach to assessing alternatives for voltage control,

Anupam A. Thatte; Marija D. Ilic

2006-01-01

465

Integrating Renewable and Distributed resources - IIT Perfect Power Smart Grid Prototype  

Microsoft Academic Search

The goal of this paper is to provide a brief overview of the Perfect Power Smart Grid Prototype at Illinois Institute of Technology, while highlighting some of the multi-agent system applications. The Perfect Power Prototype is supported by the Department of Energy under the Renewable and Distributed Systems Integration Program, which focuses on effectively integrating distributed resources (including distributed generation

Alexander J. Flueck; Cuong P. Nguyen

2010-01-01

466

Modelling of electrical power distribution systems by application of experimental design  

Microsoft Academic Search

The purpose of this paper is to demonstrate the application of the method of experimental design to the analysis of electrical power distribution systems. The theory of experimental design allows us to construct and experimentally verify the qualitative model of a power distribution system in order to analyse a significance of each component in distribution system modelling. The paper presents

Josnicjusz Nazarko

2000-01-01

467

Simulating a Multi-Agent based Self-Reconfigurable Electric Power Distribution System  

Microsoft Academic Search

Electric power distribution systems can be found almost everywhere, from ship power systems to data centers. In many critical applications, there is need to maintain minimal operating capability under fault conditions. To carry out this goal it is necessary to develop energy distribution control techniques, which let implement a self-reconfigurable energy distribution system. This research project is looking at the

Janeth G. Gómez-Gualdrón; Miguel Vélez-Reyes

2006-01-01

468

The benefits of looping a radial distribution system with a power flow controller  

Microsoft Academic Search

In this paper the benefits of looping the conventional radial distribution system by a series power electronic system to control power flow has been investigated. The conventional radial electrical distribution system will change to loop or even meshed system due to the deregulation of electrical system and connection of Distributed Generation to Medium and Low voltage in future. However looping

M. Saradarzadeh; S. Farhangi; J. L. Schanen; P.-O. Jeannin; D. Frey

2010-01-01

469

Wind Power Forecasting Error Distributions over Multiple Timescales: Preprint  

SciTech Connect

In this paper, we examine the shape of the persistence model error distribution for ten different wind plants in the ERCOT system over multiple timescales. Comparisons are made between the experimental distribution shape and that of the normal distribution.

Hodge, B. M.; Milligan, M.

2011-03-01

470

AC loss properties of a 1 MVA single-phase HTS power transformer  

Microsoft Academic Search

We designed and built a single-phase 1 MVA-22\\/6.9 kV HTS transformer with the multi-layered cylindrical windings composed of Bi2223 parallel conductors. In advance of the design, the AC loss induced in the windings was estimated on the basis of the observed results in a strand. A subcooled liquid nitrogen cryogenic system with the corresponding cooling capacity was developed and attached

M. Iwakuma; K. Funaki; K. Kajikawa; H. Tanaka; T. Bohno; A. Tomioka; H. Yamada; S. Nose; M. Konno; Y. Yagi; H. Maruyama; T. Ogata; S. Yoshida; K. Ohashi; K. Tsutsumi; K. Honda

2001-01-01

471

Magnetic properties and AC-losses of superconductors with power law current-voltage characteristics  

Microsoft Academic Search

In many high-Tc superconductors the critical current density jc is an ill-defined quantity due to the smooth current-voltage characteristic. Since jc is the basic parameter entering the critical state model, its application to such materials becomes problematic. In this paper, a theory of magnetic properties and AC-losses in superconductors with smooth current-voltage characteristics is proposed. It is applied to superconductors

Jakob Rhyner

1993-01-01

472

Distribution of MdACS3 null alleles in apple (Malus x domestica Borkh.) and its relevance to the fruit ripening characters  

PubMed Central

Expression of MdACS3a, one of the ripening-related ACC synthase genes, plays a pivotal role in initiating the burst of ethylene production by MdACS1 in apple fruit. Although previous studies have demonstrated the presence of MdACS3a-null alleles through deficiency of transcription activity or loss of enzyme activity due to amino acid substitution, which may affect the storage properties of certain fruit cultivars, an overall picture of these null alleles in cultivars is still lacking. The present study investigated the distribution of null allelic genes in 103 cultivars and 172 breeding selections by using a simple sequence repeat (SSR) marker linked to them. The results indicated that both allelic genes were widely distributed throughout the examined cultivars and selections, some occurring as the null genotype, either homozygously or heterozygously, with each null allele. The implications of MdACS3a distribution results and the influence of its null allelotypes in fruit characters are discussed.

Bai, Songling; Wang, Aide; Igarashi, Megumi; Kon, Tomoyuki; Fukasawa-Akada, Tomoko; Li, Tianzhong; Harada, Takeo; Hatsuyama, Yoshimichi

2012-01-01

473

A Service Oriented Architecture for Exploring High Performance Distributed Power Models  

SciTech Connect

Power grids are increasingly incorporating high quality, high throughput sensor devices inside power distribution networks. These devices are driving an unprecedented increase in the volume and rate of available information. The real-time requirements for handling this data are beyond the capacity of conventional power models running in central utilities. Hence, we are exploring distributed power models deployed at the regional scale. The connection of these models for a larger geographic region is supported by a distributed system architecture. This architecture is built in a service oriented style, whereby distributed power models running on high performance clusters are exposed as services. Each service is semantically annotated and therefore can be discovered through a service catalog and composed into workflows. The overall architecture has been implemented as an integrated workflow environment useful for power researchers to explore newly developed distributed power models.

Liu, Yan; Chase, Jared M.; Gorton, Ian

2012-11-12

474

Improved post-silicon power modeling using AC lock-in techniques  

Microsoft Academic Search

The objective of power modeling is to estimate the power consumption of integrated circuits under different workloads and variabilities. Post-silicon power modeling is an essential step for design validation and for building trustable pre-silicon power models and analyses. One popular approach for devising post-silicon power estimates is to translate the thermal emissions from the backside of the die into power

Abdullah Nazma Nowroz; Gary Woods; Sherief Reda

2011-01-01

475

7 CFR 1717.857 - Refinancing of existing secured debt-distribution and power supply borrowers.  

Code of Federal Regulations, 2010 CFR

...false Refinancing of existing secured debt-distribution and power supply borrowers. 1717.857 Section 1717...857 Refinancing of existing secured debtâdistribution and power supply borrowers. (a) Advance...

2010-01-01

476

7 CFR 1717.857 - Refinancing of existing secured debt-distribution and power supply borrowers.  

Code of Federal Regulations, 2010 CFR

...false Refinancing of existing secured debt-distribution and power supply borrowers. 1717.857 Section 1717...857 Refinancing of existing secured debtâdistribution and power supply borrowers. (a) Advance...

2009-01-01

477

A distributed joint scheduling and power control algorithm for multicasting in wireless ad hoc networks  

Microsoft Academic Search

This paper addresses the problem of power control in ad hoc networks supporting multicast traffic. First, we present a distributed algorithm which, given the set of multicast transmitters and their corresponding receivers, provides an optimal solution to the power control problem, if there is any. The transmit power levels obtained by solving the optimization problem minimize the network power expenditure

Kang Wang; Carla F. Chiasserini; Ramesh R. Rao; John G. Proakis

2003-01-01

478

Small inverter-interfaced distributed energy resources for reactive power support  

Microsoft Academic Search

The use of small inverter-interfaced distributed energy resources for reactive power support is discussed. While the primary function of these resources is to deliver active power, they can also be used to provide reactive power, often identified as an ancillary service by a utility. Given the large and increasing number of small grid-connected inverters, the total reactive power that can

Alejandro D. Dominguez-Garcia; Christoforos N. Hadjicostis; Philip T. Krein; Stanton T. Cady

2011-01-01

479

An Integrated Hybrid Power Supply for Distributed Generation Applications Fed by Nonconventional Energy Sources  

Microsoft Academic Search

A new, hybrid integrated topology, fed by photovoltaic (PV) and fuel cell (FC) sources and suitable for distributed generation applications, is proposed. It works as an uninterruptible power source that is able to feed a certain minimum amount of power into the grid under all conditions. PV is used as the primary source of power operating near maximum power point

Sachin Jain; Vivek Agarwal

2008-01-01

480

A methodology for the assessment of short duration voltage variations in electric power distribution systems  

Microsoft Academic Search

This paper deals with a new methodology for the assessment of power quality indices in electric power distribution systems. Power quality indices concerning short duration voltage variations, i.e. voltage sags and swells, are particularly introduced taking into account the needs for establishing power quality standards. The paper also presents a new proposal for a measurement protocol, a testing procedure to

N. Kagan; E. L. Ferrari; N. M. Matsuo; S. X. Duarte; J. L. Cavaretti; A. Tenorio; L. R. Souza

2002-01-01

481

Fault Location in Power Distribution Systems using ANFIS Nets and Current Patterns  

Microsoft Academic Search

The electric power markets have imposed new power service quality that make fault location in power distribution systems a mandatory issue. In this paper, a fault location approach based on the current waveforms measured at the power substation, the knowledge of protective device settings and ANFIS nets is presented. As a result, the approach may locate the faulted zone by

J. J. Mora; G. Carrillo; L. Perez

2006-01-01

482