WorldWideScience

Sample records for current ac power

  1. DC Vs AC - War Of Currents For Future Power Systems A HVDC Technology Overview

    Directory of Open Access Journals (Sweden)

    Anil K. Rai

    2015-08-01

    Full Text Available DC vs AC discussion began in 1880s with development of first commercial power transmission in Wall Street New York. Later when AC technology came into notice by efforts of inventor and researcher Sir Nicola Tesla soon the advantages of AC transmission and AC devices overtook the DC technology. It was hoped that DC technology had lost battle of currents. Today with researches going on FACTS devices and bulk power transmission HVDC has again gained a reputation in power sector. Solution of this centuries old debate is to develop HVDC systems that assists HVAC systems for better performance stability and control

  2. AC Loss of Ripple Current in Superconducting DC Power Transmission Cable

    Science.gov (United States)

    Yoshitomi, K.; Otabe, E. S.; Vyatkin, V. S.; Kiuchi, M.; Matsushita, T.; Hamabe, M.; Yamaguchi, S.; Inada, R.

    As a method of largely reducing the transmission loss in the electric power grid, superconducting direct current (DC) power transmission cable has been investigated. Using superconducting DC power transmission cables, large amounts of current and energy can be transferred compared to conventional copper cables. In this case, an alternating current (AC) is converted to DC and superposed AC which is known as ripple current, and the energy loss by the ripple current is generated. Therefore it is desired to estimate the energy loss density for the case of DC current and superposed AC current for a design of DC transmission cable system. In this study, the hysteresis loss for DC current of 2 kA rectified from 60 Hz alternating current is calculated using the Bean model, and coupling loss was also estimated. The diameter of the cable was 40 mm. The ripple currents generated by multi-pulse rectifiers, 6-pulse, 12-pulse, and 24-pulse were considered. It is found that the total AC loss including the hysteresis loss and the coupling loss is considerably smaller than the supposed heat loss of 0.5 W/m which is obtained with a newly developed cable.

  3. Statistical evaluation of telephone noise interference caused by AC power line harmonic currents

    Energy Technology Data Exchange (ETDEWEB)

    Kuussaari, M. (Imatran Voima Oy, Vantaa (Finland))

    1993-04-01

    A statistical approach is applied for the evaluation of the limits for harmonic currents in AC power lines, the goal being to prevent excessive telephone noise interference voltages in subscriber cables in rural areas. The analysis is based on Monte-Carlo simulation which takes into account the effect of the experiental probability distributions of the relevant parameters. In the Finnish conditions, the properties of communication cables permit equivalent disturbing phase currents of 8 to 10 A. The digital exchanges permit approximately the same currents. Some new telephone types that have a low balance may make it necessary to limit the currents to a level that is somewhat lower.

  4. Hysteresis Current Control Based Shunt Active Power Filter for Six Pulse Ac/Dc Converter

    Directory of Open Access Journals (Sweden)

    Rakesh Kumar Pandey

    2017-02-01

    Full Text Available In this paper the simulation of Shunt Active power Filter using P-Q theory and PI controller has been presented. This SAPF compensates the harmonic currents drawn by three phase six pulse AC/DC converter. The process of compensation is done by calculating the instantaneous reactive power losses using p-q theory and the PI controller to reduce the ripple voltage of the dc capacitor of the PWM-VSI. This approach is different from conventional approach and provides very effective solution. In this simulation we use hysteresis band current controller (HCC for switching the VSI inverter. The simulation has been done for both steady state and transient conditions

  5. Experimental Investigations on PV Powered SVM-DTC Induction Motor without AC Phase Current Sensors

    Directory of Open Access Journals (Sweden)

    T. Muthamizhan

    2014-05-01

    Full Text Available The paper presents a low-cost, phase-current reconstruction algorithm for space vector modulated direct torque controlled induction motor using the information obtained from only one shunt resistor which is in series with low side switches in a conventional three-phase inverter. The aim is to develop a low-cost high - performance induction motor drive. It uses the dc-link voltage and dc current to reconstruct the stator currents needed to estimate the motor flux and the electromagnetic torque. Photovoltaic arrays convert solar power to dc electric power; uses chopper and dc-ac inverter to fed three phase Induction Motor. The chopper used here is current fed full bridge boost dc-dc converter, which is preferred and extensively used in high voltage applications and advantageous over voltage fed converters. The inverter switches are controlled by PWM techniques obtained from SVM-DTC of IM. The experimental investigations are given to prove the ability of the proposed scheme of reproducing the performances of a SVM- DTC IM drive.

  6. AC Optimal Power Flow

    Energy Technology Data Exchange (ETDEWEB)

    2016-10-04

    In this work, we have implemented and developed the simulation software to implement the mathematical model of an AC Optimal Power Flow (OPF) problem. The objective function is to minimize the total cost of generation subject to constraints of node power balance (both real and reactive) and line power flow limits (MW, MVAr, and MVA). We have currently implemented the polar coordinate version of the problem. In the present work, we have used the optimization solver, Knitro (proprietary and not included in this software) to solve the problem and we have kept option for both the native numerical derivative evaluation (working satisfactorily now) as well as for analytical formulas corresponding to the derivatives being provided to Knitro (currently, in the debugging stage). Since the AC OPF is a highly non-convex optimization problem, we have also kept the option for a multistart solution. All of these can be decided by the user during run-time in an interactive manner. The software has been developed in C++ programming language, running with GCC compiler on a Linux machine. We have tested for satisfactory results against Matpower for the IEEE 14 bus system.

  7. Guiding Principles in Selecting AC To DC Converters For Power Factor Corrections in AC Transmission System

    Directory of Open Access Journals (Sweden)

    Ibekwe B.E

    2014-10-01

    Full Text Available The ac to dc converters’ power factors correction in ac transmission system were investigated. The studies include: phase-controlled converter; pulse width modulated (PWM converter and ac input current shaped converter. Using Fourier series, power factors of these converters were calculated and simulated using MATLAB. The resulting curves are displayed in the hard copies for practical guides in the choice of converters; and comparatively, current shaped type is the best.

  8. AC power generation from microbial fuel cells

    Science.gov (United States)

    Lobo, Fernanda Leite; Wang, Heming; Forrestal, Casey; Ren, Zhiyong Jason

    2015-11-01

    Microbial fuel cells (MFCs) directly convert biodegradable substrates to electricity and carry good potential for energy-positive wastewater treatment. However, the low and direct current (DC) output from MFC is not usable for general electronics except small sensors, yet commercial DC-AC converters or inverters used in solar systems cannot be directly applied to MFCs. This study presents a new DC-AC converter system for MFCs that can generate alternating voltage in any desired frequency. Results show that AC power can be easily achieved in three different frequencies tested (1, 10, 60 Hz), and no energy storage layer such as capacitors was needed. The DC-AC converter efficiency was higher than 95% when powered by either individual MFCs or simple MFC stacks. Total harmonic distortion (THD) was used to investigate the quality of the energy, and it showed that the energy could be directly usable for linear electronic loads. This study shows that through electrical conversion MFCs can be potentially used in household electronics for decentralized off-grid communities.

  9. Wind-powered asynchronous AC/DC/AC converter system. [for electric power supply regulation

    Science.gov (United States)

    Reitan, D. K.

    1973-01-01

    Two asynchronous ac/dc/ac systems are modelled that utilize wind power to drive a variable or constant hertz alternator. The first system employs a high power 60-hertz inverter tie to the large backup supply of the power company to either supplement them from wind energy, storage, or from a combination of both at a preset desired current; rectifier and inverter are identical and operate in either mode depending on the silicon control rectifier firing angle. The second system employs the same rectification but from a 60-hertz alternator arrangement; it provides mainly dc output, some sinusoidal 60-hertz from the wind bus and some high harmonic content 60-hertz from an 800-watt inverter.

  10. Software Development for DC Current Distribution in AC Power Grid%交流电网直流电流分布仿真软件的开发

    Institute of Scientific and Technical Information of China (English)

    汪发明; 张露; 全江涛; 谢齐家; 潘卓洪; 文习山

    2012-01-01

    为量化分析高压直流输电入地电流(简称直流电流)在交流电网内的分布,提出了直流分布的完整理论分析模型,实现了变电站地下网络的Thevenin等效;借助潮流计算数据取得交流电网的接线信息,开发了潮流计算接口,解决了现代大型交流电网接线运行方式的数据输入问题。运用随机模拟试验方法探讨交流电网直流分布的机理,分析了交流电网内的直流电流的分布规律:交流电网规模越大直流电流分布越广;杆塔-避雷线系统的存在会使交流电网直流电流分布密集;采用抑制措施后交流电网局部直流电流分布可能更加密集,但直流电流分布总量下降。仿真软件适用于大型交流电网直流电流分布的预测计算和抑制措施的仿真评估,可以为更好地分析、预报和抑制直流电流分布及其不良影响提供参考。%In order to analyze the HVDC transmission's earth-return current distribution in AC power grids,an improved theoretical model is set up realizing the Thevenin equivalence of underground networks.A power flow calculation interface is developed to load data of the connection of modern large-scale AC grid.Then the random test method was used to summarize the rules of DC current distribution.The results are gained as follows:the larger the AC grid,the more the DC current distribution is caused;the DC current distribution is increased by towers and overhead ground wires;though the local DC current distribution is increased,the total DC current distribution is suppressed by mitigation methods.The simulation software is suitable for DC current distribution computation and evaluating the mitigation methods,and it provides reference for analysis,forecast,mitigation,and adverse effects of DC current distributions.

  11. Direct current power delivery system and method

    Science.gov (United States)

    Zhang, Di; Garces, Luis Jose; Dai, Jian; Lai, Rixin

    2016-09-06

    A power transmission system includes a first unit for carrying out the steps of receiving high voltage direct current (HVDC) power from an HVDC power line, generating an alternating current (AC) component indicative of a status of the first unit, and adding the AC component to the HVDC power line. Further, the power transmission system includes a second unit for carrying out the steps of generating a direct current (DC) voltage to transfer the HVDC power on the HVDC power line, wherein the HVDC power line is coupled between the first unit and the second unit, detecting a presence or an absence of the added AC component in the HVDC power line, and determining the status of the first unit based on the added AC component.

  12. Control of Power Converters in AC Microgrids

    DEFF Research Database (Denmark)

    Rocabert, Joan; Luna, Alvaro; Blaabjerg, Frede

    2012-01-01

    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 ele......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...

  13. Distributed AC power flow method for AC and AC-DC hybrid ...

    African Journals Online (AJOL)

    DR OKE

    Present MGs incorporate AC and DC sources and loads along with storage and power ... Keywords: Microgrid (MG), Distributed Energy Resources (DER), Particle ... But in case of renewable based MGs, where small and intermittent sources ...

  14. Power quality issues current harmonics

    CERN Document Server

    Mikkili, Suresh

    2015-01-01

    Power Quality Issues: Current Harmonics provides solutions for the mitigation of power quality problems related to harmonics. Focusing on active power filters (APFs) due to their excellent harmonic and reactive power compensation in two-wire (single phase), three-wire (three-phase without neutral), and four-wire (three-phase with neutral) AC power networks with nonlinear loads, the text:Introduces the APF technology, describing various APF configurations and offering guidelines for the selection of APFs for specific application considerationsCompares shunt active filter (SHAF) control strategi

  15. Current Control of Grid Converters Connected with Series AC Capacitor

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

    2015-01-01

    The series ac capacitor has recently been used with the transformerless grid-connected converters in the distribution power grids. The capacitive characteristic of the resulting series LC filter restricts the use of conventional synchronous integral or stationary resonant current controllers. Thus...

  16. 21 CFR 886.1850 - AC-powered slitlamp biomicroscope.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered slitlamp biomicroscope. 886.1850... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1850 AC-powered slitlamp biomicroscope. (a) Identification. An AC-powered slitlamp biomicroscope is an AC-powered device that is...

  17. 21 CFR 886.4440 - AC-powered magnet.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered magnet. 886.4440 Section 886.4440 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4440 AC-powered magnet. (a) Identification. An AC-powered magnet is an AC-powered device that generates a magnetic field intended to find and...

  18. 21 CFR 888.1240 - AC-powered dynamometer.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered dynamometer. 888.1240 Section 888.1240...) MEDICAL DEVICES ORTHOPEDIC DEVICES Diagnostic Devices § 888.1240 AC-powered dynamometer. (a) Identification. An AC-powered dynamometer is an AC-powered device intended for medical purposes to...

  19. 21 CFR 886.1630 - AC-powered photostimulator.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered photostimulator. 886.1630 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1630 AC-powered photostimulator. (a) Identification. An AC-powered photostimulator is an AC-powered device intended to provide light stimulus...

  20. POWER FACTOR IMPROVEMENT IN THREE PHASE AC-AC CONVERTER THROUGH MODIFIED SPWM

    Directory of Open Access Journals (Sweden)

    P.VASUKI,

    2011-02-01

    Full Text Available Recently, a new generation of ac-ac single-phase and three-phase power converters with more commutations per half cycle has been proposed for ac power due to the increasing availability and power capability of high frequency controlled-on and off power emiconductor switching devices. This paper presents three phase ac-acconverter whose control strategy is based on modified sinusoidal ulse-width modulation switching technique. As majority of the industrial loads are being inductive, the power factor is less. To improve the power factor, the delayed current is shifted to the input voltage, through a modification of the classical sinusoidal pulse width modulation switching technique. In this way, the decrease in the phase angle between the input current and voltage is feasible, and consequently, high cost compensation capacitors can be avoided. The improvement of power factor through this switching technique on the proposed converter is investigated and verified via simulation using the software Matlab/Simulink.

  1. Total AC loss of YBCO coated conductor carrying AC transport current in AC transverse magnetic field with various orientations

    Energy Technology Data Exchange (ETDEWEB)

    Amemiya, Naoyuki [Faculty of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501 (Japan); Jiang, Zhenan [Faculty of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501 (Japan); Iijima, Yasuhiro [Materials Research Laboratory, Fujikura Ltd, 1-5-1 Kiba, Koto, Tokyo 135-8512 (Japan); Kakimoto, Kazuomi [Materials Research Laboratory, Fujikura Ltd, 1-5-1 Kiba, Koto, Tokyo 135-8512 (Japan); Saitoh, Takashi [Materials Research Laboratory, Fujikura Ltd, 1-5-1 Kiba, Koto, Tokyo 135-8512 (Japan)

    2004-08-01

    Using an electro-magnetic method, we measured the total AC loss of a YBCO coated conductor carrying an AC transport current in an AC transverse magnetic field with various orientations. We measured the magnetization loss (energy flow from the external magnetic field) and the transport loss (energy flow from the transport current circuit) independently during simultaneous application of an AC transverse magnetic field and AC transport current. Their sum gave us the total AC loss. The transport loss increases with increasing AC transverse magnetic field, and the magnetization loss increases with increasing AC transport current. The AC transverse magnetic field and the AC self magnetic field interact with each other at the conductor edges. This nonlinear interaction is a possible cause of the increase in AC loss. Due to the high aspect ratio of YBCO coated conductors, this increase in AC loss due to the interaction between the AC transverse and AC self magnetic fields is observed even when the transverse magnetic field is nearly parallel to the conductor wide-face. When the total AC losses for various transport currents and various field orientations are plotted against a transverse magnetic field component which is perpendicular to the conductor wide-face, the plots with different field angles but identical transport current all agree quite well with each other. The total AC loss is dominated by the self magnetic field and the perpendicular component of the transverse magnetic field, both of which mostly penetrate from the conductor edges.

  2. Power control for ac motor

    Science.gov (United States)

    Dabney, R. W. (Inventor)

    1984-01-01

    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.

  3. Low power DCVSL circuits employing AC power supply

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In view of changing the type of energy conversion in CMOS circuits, this paper investigates low power CMOS circuit design, which adopts a gradually changing power clock. First, we discuss the algebraic expressions and the corresponding properties of clocked power signals. Then the design procedure is summed up for converting complementary CMOS logic gates employing DC power to the power-clocked CMOS gates employing AC power. On this basis, the design of differential cascode voltage switch logic (DCVSL) circuits employing AC power clocks is proposed. The PSPICE simulations using a sinusoidal power-clock demonstrate that the designed power-clocked DCVSL circuit has a correct logic function and low power characteristics. Finally, an interface circuit to convert clocked signals into the standard logic levels of a CMOS circuit is proposed, and its validity is verified by computer simulations.

  4. Reliability of emergency ac power systems at nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Battle, R E; Campbell, D J

    1983-07-01

    Reliability of emergency onsite ac power systems at nuclear power plants has been questioned within the Nuclear Regulatory Commission (NRC) because of the number of diesel generator failures reported by nuclear plant licensees and the reactor core damage that could result from diesel failure during an emergency. This report contains the results of a reliability analysis of the onsite ac power system, and it uses the results of a separate analysis of offsite power systems to calculate the expected frequency of station blackout. Included is a design and operating experience review. Eighteen plants representative of typical onsite ac power systems and ten generic designs were selected to be modeled by fault trees. Operating experience data were collected from the NRC files and from nuclear plant licensee responses to a questionnaire sent out for this project.

  5. Safe-commutation principle for direct single-phase AC-AC converters for use in audio power amplification

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2004-01-01

    This paper presents an alternative safe commutation principle for a single phase bidirectional bridge, for use in the new generation of direct single-stage AC-AC audio power amplifiers. As compared with the bridge commutation with load current or source voltage sensing, in this approach...

  6. Safe-commutation principle for direct single-phase AC-AC converters for use in audio power amplification

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2004-01-01

    This paper presents an alternative safe commutation principle for a single phase bidirectional bridge, for use in the new generation of direct single-stage AC-AC audio power amplifiers. As compared with the bridge commutation with load current or source voltage sensing, in this approach...

  7. AC Power Local Network with Multiple Power Routers

    Directory of Open Access Journals (Sweden)

    Ryo Takahashi

    2013-12-01

    Full Text Available Controlling power flow and achieving appropriate matching between power sources and loads according to the quality of energy is expected to be one of the approaches to reduce wasted energy consumption. A power router, proposed recently, has the capability of realizing circuit switching in a power distribution network. This study focuses on the feasibility of an AC power routing network system composed of multiple power routers. To evaluate the feasibility, we experimentally confirm the circuit switching operation of the parallel and series configurations of the power routers, so that the network system can be designed by the combination of parallel and series configurations.

  8. Resistojet control and power for high frequency ac buses

    Science.gov (United States)

    Gruber, Robert P.

    1987-01-01

    Resistojets are operational on many geosynchronous communication satellites which all use dc power buses. Multipropellant resistojets were selected for the Initial Operating Capability (IOC) Space Station which will supply 208 V, 20 kHz power. This paper discusses resistojet heater temperature controllers and passive power regulation methods for ac power systems. A simple passive power regulation method suitable for use with regulated sinusoidal or square wave power was designed and tested using the Space Station multipropellant resistojet. The breadboard delivered 20 kHz power to the resistojet heater. Cold start surge current limiting, a power efficiency of 95 percent, and power regulation of better than 2 percent were demonstrated with a two component, 500 W breadboard power controller having a mass of 0.6 kg.

  9. Input-current shaped ac to dc converters

    Science.gov (United States)

    1986-01-01

    The problem of achieving near unity power factor while supplying power to a dc load from a single phase ac source of power is examined. Power processors for this application must perform three functions: input current shaping, energy storage, and output voltage regulation. The methods available for performing each of these three functions are reviewed. Input current shaping methods are either active or passive, with the active methods divided into buck-like and boost-like techniques. In addition to large reactances, energy storage methods include resonant filters, active filters, and active storage schemes. Fast voltage regulation can be achieved by post regulation or by supplementing the current shaping topology with an extra switch. Some indications of which methods are best suited for particular applications concludes the discussion.

  10. A Study on Power Quality Improvement in PWM Controlled AC Voltage Controller

    Directory of Open Access Journals (Sweden)

    Ahmet ALTINTAŞ

    2009-04-01

    Full Text Available A lot of topologies of pulse-width modulated (PWM-AC controllers for single-phase and three-phase systems are proposed up to date. PWM-AC controllers have important advantages compared with the phase-controlled AC controllers using thyristors and triacs. The PWM-AC controller has sinusoidal current waveforms, smaller THD values, better power factor, faster dynamics, and smaller input/output filter. This article presents a novel control technique for application to PWM-AC controllers with ability of generating fewer harmonics. In the proposed control method, both the traditional AC voltage controllers and the PWM-AC controllers are combined; and smaller THD values are obtained. Thus, the harmonic pollution in the power system will be reduced; and consequently, the power quality will be increased. For this purpose, computer simulations are performed in order to investigate the proposed controller performance. The obtained results are compared with the conventional PWM-AC controller.

  11. Transcranial alternating current stimulation (tACS

    Directory of Open Access Journals (Sweden)

    Andrea eAntal

    2013-06-01

    Full Text Available Transcranial alternating current stimulation (tACS seems likely to open a new era of the field of noninvasive electrical stimulation of the human brain by directly interfering with cortical rhythms. It is expected to synchronize (by one single resonance frequency or desynchronize (e.g. by the application of several frequencies cortical oscillations. If applied long enough it may cause neuroplastic effects. In the theta range it may improve cognition when applied in phase. Alpha rhythms could improve motor performance, whereas beta intrusion may deteriorate them. TACS with both alpha and beta frequencies has a high likelihood to induce retinal phosphenes. Gamma intrusion can possibly interfere with attention. Stimulation in the ripple range induces intensity dependent inhibition or excitation in the motor cortex most likely by entrainment of neuronal networks, whereas stimulation in the low kHz range induces excitation by neuronal membrane interference. TACS in the 200 kHz range may have a potential in oncology.

  12. An AC/AC Direct Power Conversion Topology Having Multiple Power Grid Connections with Adjustable Loading

    DEFF Research Database (Denmark)

    Klumpner, Christian; Blaabjerg, Frede

    2004-01-01

    Normally, a power converter has one supply port to connect to the power grid and one or multiple output ports to connect to AC loads that require variable voltage and variable frequency. As the trend on the energy market is towards deregulation, new converter topologies are needed to allow...... independent producers/consumers to connect to multiple distribution grids in order to optimise the electricity price, as this will vary during the day from one power distribution company to another one. It will be needed to have a load that can smoothly adjust the power consumed from each power grid in order...... these fraction power will be a necessary feature on a deregulated energy market. This paper presents a new topology of a power converter based on the Direct Power Conversion concept, which is able to connect to multiple grids and provide complete decoupling between without circulating power between the grids...

  13. Distributed Optimal Power Flow of AC/DC Interconnected Power Grid Using Synchronous ADMM

    Science.gov (United States)

    Liang, Zijun; Lin, Shunjiang; Liu, Mingbo

    2017-05-01

    Distributed optimal power flow (OPF) is of great importance and challenge to AC/DC interconnected power grid with different dispatching centres, considering the security and privacy of information transmission. In this paper, a fully distributed algorithm for OPF problem of AC/DC interconnected power grid called synchronous ADMM is proposed, and it requires no form of central controller. The algorithm is based on the fundamental alternating direction multiplier method (ADMM), by using the average value of boundary variables of adjacent regions obtained from current iteration as the reference values of both regions for next iteration, which realizes the parallel computation among different regions. The algorithm is tested with the IEEE 11-bus AC/DC interconnected power grid, and by comparing the results with centralized algorithm, we find it nearly no differences, and its correctness and effectiveness can be validated.

  14. A Switched Capacitor Based AC/DC Resonant Converter for High Frequency AC Power Generation

    Directory of Open Access Journals (Sweden)

    Cuidong Xu

    2015-09-01

    Full Text Available A switched capacitor based AC-DC resonant power converter is proposed for high frequency power generation output conversion. This converter is suitable for small scale, high frequency wind power generation. It has a high conversion ratio to provide a step down from high voltage to low voltage for easy use. The voltage conversion ratio of conventional switched capacitor power converters is fixed to n, 1/n or −1/n (n is the switched capacitor cell. In this paper, A circuit which can provide n, 1/n and 2n/m of the voltage conversion ratio is presented (n is stepping up the switched capacitor cell, m is stepping down the switching capacitor cell. The conversion ratio can be changed greatly by using only two switches. A resonant tank is used to assist in zero current switching, and hence the current spike, which usually exists in a classical switching switched capacitor converter, can be eliminated. Both easy operation and efficiency are possible. Principles of operation, computer simulations and experimental results of the proposed circuit are presented. General analysis and design methods are given. The experimental result verifies the theoretical analysis of high frequency AC power generation.

  15. Stability Enhancement of Power System by Controlling Hvdc Power Flow through the Same Ac Transmission Line

    Directory of Open Access Journals (Sweden)

    P. Upendra Kumar

    2014-04-01

    Full Text Available Long extra high voltage (EHV ac lines cannot be loaded to their thermal limits in order to keep sufficient margin against transient instability. With the scheme proposed in this paper, it is possible to load these lines very close to their thermal limits. The conductors are allowed to carry usual ac along with dc superimposed on it. The added dc power flow does not cause any transient instability. This paper presents the feasibility of converting a double circuit ac line into composite ac–dc power transmission line to get the advantages of parallel ac–dc transmission to improve stability and damping out oscillations. Simulation and experimental studies are carried out for the coordinated control as well as independent control of ac and dc power transmissions. No alterations of conductors, insulator strings, and towers of the original line are needed. Substantial gain in the loadability of the line is obtained. Master current controller senses ac current and regulates the dc current orders for converters online such that conductor current never exceeds its thermal limit. The present paper is implemented by using MATLAB/SIMULINK.

  16. EHV AC undergrounding electrical power performance and planning

    CERN Document Server

    Benato, Roberto

    2014-01-01

    Analytical methods of cable performance in EHV AC electrical power are discussed in this comprehensive reference. Descriptions of energization, power quality, cable safety constraints and more, guide readers in cable planning and power network operations.

  17. Effect of the magnetic material on AC losses in HTS conductors in AC magnetic field carrying AC transport current

    Science.gov (United States)

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

    2015-11-01

    This paper presents an investigation on the AC losses in several typical superconducting composite conductors using the H-formulation model. A single superconducting strip with ferromagnetic substrate or cores and a stack of coated conductors with ferromagnetic substrates are studied. We consider all the coated conductors carrying AC transport currents and simultaneously exposed to perpendicular AC magnetic fields. The influences of the amplitude, frequency, phase difference and ferromagnetic materials on the AC losses are investigated. The results show that the magnetization losses of single strip and stacked strips have similar characteristics. The ferromagnetic substrate can increase the magnetization loss at low magnetic field, and decrease the loss at high magnetic field. The ferromagnetic substrate can obviously increase the transport loss in stacked strips. The trends of total AC losses of single strip and stacked strips are similar when they are carrying current or exposed to a perpendicular magnetic field. The effect of the frequency on the total AC losses of single strip is related to the amplitude of magnetic field. The AC losses decrease with increasing frequency in low magnetic field region while increase in high magnetic field region. As the phase difference changes, there is a periodic variation for the AC losses. Moreover, when the strip is under only the transport current and magnetic field, the ferromagnetic cores will increase the AC losses for large transport current or field.

  18. Approaches to building single-stage AC/AC conversion switch-mode audio power amplifiers

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2004-01-01

    This paper discusses the possible topologies and promising approaches towards direct single-phase AC-AC conversion of the mains voltage for audio applications. When compared to standard Class-D switching audio power amplifiers with a separate power supply, it is expected that direct conversion...

  19. Power Electronic Transformer based Three-Phase PWM AC Drives

    Science.gov (United States)

    Basu, Kaushik

    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

  20. AC Versus DC Link Comparison Based on Power Flow Analysis of a Multimachine Power System

    OpenAIRE

    Mohammed Abdeljalil DJEHAF; Sid Ahmed ZIDI; Youcef DJILANI KOBIBI

    2014-01-01

    Deregulation and privatization is posing new challenges on high voltage transmission and on distributions systems as well. An increasingly liberalized market will encourage trading opportunities to be identified and developed. High voltage power electronics, such as HVDC (High Voltage Direct Current) and FACTS (Flexible AC Transmission Systems) provide the necessary features to avoid technical problems in heavily loaded power systems; HVDC offers most advantages: it can be used for system int...

  1. A hybrid electromechanical solid state switch for ac power control

    Science.gov (United States)

    1972-01-01

    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.

  2. Single phase AC-DC power factor corrected converter with high frequency isolation using buck converter

    Directory of Open Access Journals (Sweden)

    R. Ramesh,

    2014-03-01

    Full Text Available Single phase ac-dc converters having high frequency isolation are implemented in buck, boost, buck-boost configuration with improving the power quality in terms of reducing the harmonics of input current. The paperpropose the circuit configuration, control mechanism, and simulation result for the single phase ac-dc converter.

  3. Current power plant

    Energy Technology Data Exchange (ETDEWEB)

    Nickell, J.H.

    1979-03-06

    A current power plant is described that includes a shaft mounted turbine wheel for employment in water current, a housing adjacent the impeller and to which the shaft extends, a ramp positioned on the upstream side of the impellar, and a frame on which the turbine wheel is mounted. The frame is mounted by rollers on a tract such that the impeller and frame may be rolled on the tracks inside the housing, whereafter doors are closed, and water around the turbine wheel may be pumped out to facilitate turbine repair.

  4. Phosphor-in-glass for high-powered remote-type white AC-LED.

    Science.gov (United States)

    Lin, Hang; Wang, Bo; Xu, Ju; Zhang, Rui; Chen, Hui; Yu, Yunlong; Wang, Yuansheng

    2014-12-10

    The high-powered alternating current (AC) light-emitting diode (LED) (AC-LED), featuring low cost, high energy utilization efficiency, and long service life, will become a new economic growth point in the field of semiconductor lighting. However, flicker of AC-LED in the AC cycles is not healthy for human eyes, and therefore need to be restrained. Herein we report an innovation of persistent "phosphor-in-glass" (PiG) for the remote-type AC-LED, whose afterglow can be efficiently activated by the blue light. It is experimentally demonstrated that the afterglow decay of PiG in the microsecond range can partly compensate the AC time gap. Moreover, the substitution of inorganic glass for organic resins or silicones as the encapsulants would bring out several technological benefits to AC-LED, such as good heat-dissipation, low glare, and excellent physical/chemical stability.

  5. Predictive Current Control of a 7-level AC-DC back-to-back Converter for Universal and Flexible Power Management System

    DEFF Research Database (Denmark)

    Bifaretti, Steffano; Zanchetta, Pericle; Iov, Florin

    2008-01-01

    /or various distributed generation systems. Effective and accurate power flow control is demonstrated through simulation in Matlab- Simulink environment on a model based on a two-port structure and using a Predictive Control technique. Control of different Power flow profiles has been successfully tested...

  6. AC Versus DC Link Comparison Based on Power Flow Analysis of a Multimachine Power System

    Directory of Open Access Journals (Sweden)

    Mohammed Abdeljalil DJEHAF

    2014-02-01

    Full Text Available Deregulation and privatization is posing new challenges on high voltage transmission and on distributions systems as well. An increasingly liberalized market will encourage trading opportunities to be identified and developed. High voltage power electronics, such as HVDC (High Voltage Direct Current and FACTS (Flexible AC Transmission Systems provide the necessary features to avoid technical problems in heavily loaded power systems; HVDC offers most advantages: it can be used for system interconnection and for control of power flow as well. The major benefit of HVDC is its incorporated ability for fault-current blocking, which is not possible with synchronous AC links. In addition, HVDC can effectively support the surrounding AC systems in case of transient fault conditions and it serves as firewall against cascading disturbances. This paper presents a comparison between HVDC link and an HVAC link in a 29 Bus multimachine system, based on load flow analysis using Newton-Raphson method for the AC link case, and sequential method for the HVDC link case.

  7. Electrical Model of Balanced AC HTS Power Cable

    Science.gov (United States)

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

    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.

  8. Analytical approximation for AC losses in thin power-law superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Sokolovsky, V; Meerovich, V [Physics Department, Ben-Gurion University of the Negev, PO Box 653, Beer-Sheva, 84105 (Israel)

    2007-08-15

    AC losses in the superconducting parts of tapes and multifilamentary coated conductors that are subjected to AC magnetic fields are an important component of the total losses in such composites. The analytical expression for AC losses in a thin superconducting strip with a power-law voltage-current characteristic and critical current depending on a magnetic field is obtained for the case of asymptotically high perpendicular magnetic fields. The losses caused by closure currents are estimated. The results show that the Bean model gives significantly understated values for coated conductors. The applicability of the obtained expressions is analyzed.

  9. Power Controllability of Three-phase Converter with Unbalanced AC Source

    DEFF Research Database (Denmark)

    Ma, Ke; Chen, Wenjie; Liserre, Marco

    2015-01-01

    Three-phase DC-AC power converters suffer from power oscillation and overcurrent problems in case of unbalanced AC source voltage that can be caused by grid/generator faults. Existing solutions to handle these problems are properly selecting and controlling the positive and negative sequence...... currents. In this work a new series of control strategies which utilize the zerosequence components are proposed to enhance the power control ability under this adverse condition. It is concluded that by introducing proper zero sequence current controls and corresponding circuit configurations, the power...... converter can enable more flexible control targets, achieving better performances in the delivered power and load current when suffering from unbalanced AC voltage....

  10. Power Controllability of Three-phase Converter with Unbalanced AC Source

    DEFF Research Database (Denmark)

    Ma, Ke; Liserre, Marco; Blaabjerg, Frede

    2013-01-01

    Three-phase DC-AC power converters suffer from power oscillation and overcurrentt problems in case of unbalanced AC source voltage that can be caused by grid/generator faults. Existing solutions to handle these problems are properly selecting and controlling the positive and negative sequence...... converter can enable more flexible control targets, achieving better performances in the delivered power and load current when suffering from unbalanced AC sources....... currents. In this work a new series of control strategies which utilize the zero-sequence components are proposed to enhance the power control ability under this adverse conditions. It is concluded that by introducing proper zero sequence current controls and corresponding circuit configurations, the power...

  11. Three-phase AC-AC power converters based on matrix converter topology matrix-reactance frequency converters concept

    CERN Document Server

    Szczesniak, Pawel

    2013-01-01

    AC voltage frequency changes is one of the most important functions of solid state power converters. The most desirable features in frequency converters are the ability to generate load voltages with arbitrary amplitude and frequency, sinusoidal currents and voltages waveforms; the possibility of providing unity power factor for any load; and, finally, a simple and compact power circuit. Over the past decades, a number of different frequency converter topologies have appeared in the literature, but only the converters with either a voltage or current DC link are commonly used in industrial app

  12. Frequency-dependent critical current and transport ac loss of superconductor strip and Roebel cable

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Kailash Prasad [Landcare Research, Palmerston North 4442 (New Zealand); Raj, Ashish [Computer Science in Radiology, Weill Medical College, Cornell University, NY 10022 (United States); Brandt, Ernst Helmut [Max-Planck-Institut fuer Metallforschung, PO B 800665, D-70506 Stuttgart (Germany); Kvitkovic, Jozef; Pamidi, Sastry V, E-mail: thakurk@landcareresearch.co.nz, E-mail: asr2004@med.cornell.edu, E-mail: ehb@mf.mpg.de, E-mail: kvitkovic@caps.fsu.edu, E-mail: pamidi@caps.fsu.edu [Center for Advanced Power System, Florida State University, Tallahassee, FL 32310 (United States)

    2011-06-15

    The frequency-dependent critical current of a superconductor strip and Roebel cable has been studied using a 2D finite element simulation. It is shown that the critical current of the superconductor increases with frequency as f{sup 1/n}, where n is the exponent of the power law flux creep model. Transport ac loss in a superconductor strip decreases with frequency as f{sup -2/n} when the amplitude of the applied ac current is far less than its critical current. However, when the applied current is large and becomes comparable to the critical current, the transport ac loss decreases with frequency as 1/f. The analytical results are substantiated with available experimental data and the results of a 2D finite element simulation.

  13. Power converters and AC electrical drives with linear neural networks

    CERN Document Server

    Cirrincione, Maurizio

    2012-01-01

    The first book of its kind, Power Converters and AC Electrical Drives with Linear Neural Networks systematically explores the application of neural networks in the field of power electronics, with particular emphasis on the sensorless control of AC drives. It presents the classical theory based on space-vectors in identification, discusses control of electrical drives and power converters, and examines improvements that can be attained when using linear neural networks. The book integrates power electronics and electrical drives with artificial neural networks (ANN). Organized into four parts,

  14. Active Power Regulation based on Droop for AC Microgrid

    DEFF Research Database (Denmark)

    Li, Chendan; Coelho, Ernane A. A.; Firoozabadi, Mehdi Savaghebi

    2015-01-01

    In this paper, two different control strategies are proposed to address the active power regulation issue in AC microgrids. The principle of power regulation in the droop controller is firstly introduced. Frequency scheduling and droop gain scheduling on top of droop control is proposed to succes......In this paper, two different control strategies are proposed to address the active power regulation issue in AC microgrids. The principle of power regulation in the droop controller is firstly introduced. Frequency scheduling and droop gain scheduling on top of droop control is proposed...

  15. Solid-state fast voltage compensator for pulsed power applications requiring constant AC power consumption

    CERN Document Server

    Magallanes, Francisco Cabaleiro; Viarouge, Philippe; Cros, Jérôme

    2015-01-01

    This paper proposes a novel topological solution for pulsed power converters based on capacitor-discharge topologies, integrating a Fast Voltage Compensator which allows an operation at constant power consumption from the utility grid. This solution has been retained as a possible candidate for the CLIC project under study at CERN, which requires more than a thousand synchronously-operated klystron modulators producing a total pulsed power of almost 40 GW. The proposed Fast Voltage Compensator is integrated in the modulator such that it only has to treat the capacitor charger current and a fraction of the charging voltage, meaning that its dimensioning power and cost are minimized. This topology can be used to improve the AC power quality of any pulsed converters based on capacitor-discharge concept. A prototype has been built and exploited to validate the operating principle and demonstrate the benefits of the proposed solution.

  16. Asymmetric operation of AC power transmission systems : the key to optimizing power system reliability and economics

    Energy Technology Data Exchange (ETDEWEB)

    Marceau, R.J. [University of Ontario Inst. of Technology, Oshawa, ON (Canada); McGillis, D.T. [McGill Univ., Montreal, PQ (Canada). Dept. of Electrical and Computer Engineering]|[Concordia Univ., Montreal, PQ (Canada). Dept. of Electrical and Computer Engineering; Sana, A.R.

    2006-07-01

    This book provides an invaluable tool for professionals working in the field of electrical engineering and applied science. It presents a simple and cost-effective strategy to operate alternating current (AC) power transmission systems more reliably and economically. Typically, bulk power transmission systems are operated symmetrically. When a problem such as a short-circuit occurs on a 3-phase line on an individual phase, all 3 phases are taken out of service. Such a strategy is fundamentally inefficient, given that most faults are single-line-to-ground faults. The more effective operating strategy presented in this book is based on the concept of asymmetric operation, which defines the operation of a 3-phase AC transmission line as 3 independently operated entities. As such, a 3-phase line can be operated with 1 or 2 phases out of service for single-line transmission corridors or with 1 , 2 or 3 phases out of service in the case of multiple-line corridors. This approach also maintains 3-phase symmetrical operation at its extremities, thereby protecting loads and power plants from undesirable voltages and currents. The overall integrity of 3-phase transmission is maintained in terms of power delivery, balanced voltages and currents even in the event of failures in part of the transmission system. The result is improved security. 67 refs., 42 tabs., 73 figs., 2 appendices.

  17. Modelling ac ripple currents in HTS coated conductors

    Science.gov (United States)

    Xu, Zhihan; Grilli, Francesco

    2015-10-01

    Dc transmission using high temperature superconducting (HTS) coated conductors (CCs) offers a promising solution to the globally growing demand for effective, reliable and economic transmission of green energy up to the gigawatt level over very long distances. The credible estimation of the losses and thereby the heat dissipation involved, where ac ripples (introduced in rectification/ac-dc conversion) are viewed as a potential source of notable contribution, is highly essential for the rational design of practical HTS dc transmission cables and corresponding cryogenic systems to fulfil this demand. Here we report a targeted modelling study into the ac losses in a HTS CC subject to dc and ac ripple currents simultaneously, by solving Maxwell’s equations using the finite element method (FEM) in the commercial software package COMSOL. It is observed that the instantaneous loss exhibits only one peak per cycle in the HTS CC subject to sinusoidal ripples, given that the amplitude of the ac ripples is smaller than approximately 20% of that of the dc current. This is a distinct contrast to the usual observation of two peaks per cycle in a HTS CC subject to ac currents only. The unique mechanism is also revealed, which is directly associated with the finding that, around any local minima of the applied ac ripples, the critical state of -J c is never reached at the edges of the HTS CC, as it should be according to the Bean model. When running further into the longer term, it is discovered that the ac ripple loss of the HTS CC in full-wave rectification decays monotonically, at a speed which is found to be insensitive to the frequency of the applied ripples within our targeted situations, to a relatively low level of approximately 1.38 × 10-4 W m-1 in around 1.7 s. Comparison between this level and other typical loss contributions in a HTS dc cable implies that ac ripple currents in HTS CCs should only be considered as a minor source of dissipation in superconducting dc

  18. Rethinking Rectification: AC-DC Power Supply in Package

    DEFF Research Database (Denmark)

    Pejtersen, Jens; Knott, Arnold; Jørgensen, Ivan Harald Holger

    Rectification of AC mains voltage is almost exclusively implemented with passive diode bridge rectifiers for power applications below 100 W. The diode bridge rectifier is reliable, cost effective and easy to use. But it is also lossy, nonlinear and passive. Thus reducing the power conversion...

  19. Djungle power. A more remote AC bus

    Energy Technology Data Exchange (ETDEWEB)

    Boehnke, Heinz W. [Technosol, Jork (Germany)

    2010-07-01

    The Dzanga-Sangha Reserve in the Central African Republic is probably one of the world's most remote protected rainforest areas, much to the benefit of the rare species of lowland gorilla, forest elephant and local pygmy population Ba'Aka. The park is co-managed by the ''WWF-World Wide Fund for Nature'' with sponsoring from the German Regenwald-Stiftung. In 2008 wwf decided to switch from the old, failing generator supply to a solar hybrid mini-grid, along with stringent measures of energy conservation and management. After a careful energy audit Technosol designed an AC-bus system with a 22 kWp PV generator which should overcome the dependency on the old generators and their fuel demands. For 15 buildings, an entirely new distribution network was installed, state of the art energy saving devices introduced and an energy metering system deviced. The installation is operating since August 2009. In such remote locations, the reliability of the AC-bus over other generator-based solutions will be demonstrated and with the support of international organisations like the wwf the practical application of solar hybrid supply becomes a landmark of sustainable energy concepts. (orig.)

  20. 21 CFR 880.6320 - AC-powered medical examination light.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered medical examination light. 880.6320... Miscellaneous Devices § 880.6320 AC-powered medical examination light. (a) Identification. An AC-powered medical examination light is an AC-powered device intended for medical purposes that is used to illuminate...

  1. Modeling AC ripple currents in HTS coated conductors by integral equations

    Science.gov (United States)

    Grilli, Francesco; Xu, Zhihan

    2016-12-01

    In several HTS applications, the superconducting tapes experience the simultaneous presence of DC and AC excitations. For example in high-current DC cables, where the transport current is not perfectly constant, but it exhibits some ripples at different frequencies introduced by the rectification process (AC-DC conversion). These ripples give rise to dissipation, whose magnitude and possible influence on the device's cooling requirements need to be evaluated. Here we report a study of the AC losses in a HTS coated conductor subjected to DC currents and AC ripples simultaneously. The modeling approach is based on an integral equation method for thin superconductors: the superconducting tape is modeled as a 1-D object with a non-linear resistivity, which includes the dependence of the critical current density Jc on the magnetic field. The model, implemented in a commercial finite-element program, runs very fast (the simulation of one AC cycle typically takes a few seconds on standard desktop workstation): this allows simulating a large number of cycles and estimating when the AC ripple losses stabilize to a constant value. The model is used to study the influence of the flux creep power index n on the stabilization speed and on the AC loss values, as well as the effect of using a field-dependent Jc instead of a constant one. The simulations confirm that the dissipation level should not be a practical concern in HTS DC cables. At the same time, however, they reveal a strong dependence of the results upon the power index n and the form of Jc , which spurs the question whether the power-law is the most suitable description of the superconductor's electrical behavior for this kind of analysis.

  2. Compensation methods applied in current control schemes for large AC drive systems

    DEFF Research Database (Denmark)

    Rus, D. C.; Preda, N. S.; Teodorescu, Remus;

    2012-01-01

    The paper deals with modified PI current control structures for large AC drive systems which use surface mounted permanent magnet synchronous machines or squirrel-cage induction motors supplied with voltage source inverters. In order to reduce the power losses caused by high frequency switching...

  3. Power flow control of intertied ac microgrids

    DEFF Research Database (Denmark)

    Nutkani, Inam Ullah; Loh, Poh Chiang; Blaabjerg, Frede

    2013-01-01

    of interlinking power converters. Active and reactive power flows of these converters should preferably be managed autonomously without demanding for fast communication links. A scheme that can fulfill the objectives is now proposed, which upon realised, will result in more robustly integrated microgrids...

  4. Thermal Impact Analysis of Circulating Current in High Power Modular Online Uninterruptible Power Supplies Application

    DEFF Research Database (Denmark)

    Zhang, Chi; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2017-01-01

    In modular uninterruptible power supplies (UPSs), several DC/AC modules are required to work in parallel. This structure allows the system to be more reliable and flexible. These DC/AC modules share the same DC bus and AC critical bus. Module differences, such as filter inductor, filter capacitor......, control parameters, and so on, will make it possible for the potential zero sequence current to flow among the modules. This undesired type of circulating current will bring extra losses to the power semiconductor devices in the system, which should be paid special attention in high power application...

  5. Compensation for Harmonic Currents and Reactive Power in Wind Power Generation System using PWM Inverter

    Science.gov (United States)

    Shinohara, Katsuji; Shinhatsubo, Kurato; Iimori, Kenichi; Yamamoto, Kichiro; Saruban, Takamichi; Yamaemori, Takahiro

    In recent year, consciousness of environmental problems is enhancing, and the price of the electric power purchased by an electric power company is established expensive for the power plant utilizing the natural energy. So, the introduction of the wind power generation is promoted in Japan. Generally, squirrel-cage induction machines are widely used as a generator in wind power generation system because of its small size, lightweight and low-cost. However, the induction machines do not have a source of excitation. Thus, it causes the inrush currents and the instantaneous voltage drop when the generator is directly connected to a power grid. To reduce the inrush currents, an AC power regulator is used. Wind power generations are frequently connected to and disconnected from the power grid. However, when the inrush currents are reduced, harmonic currents are caused by phase control of the AC power regulator. And the phase control of AC power regulator cannot control the power factor. Therefore, we propose the use of the AC power regulator to compensate for the harmonic currents and reactive power in the wind power generation system, and demonstrate the validity of its system by simulated and experimental results.

  6. Distributed AC power flow method for AC and AC-DC hybrid ...

    African Journals Online (AJOL)

    DR OKE

    Hence the distribution power flow models to be developed were supposed to include both mesh and DG modeling (Sedghi ... Newton-Raphson based power flow methods, namely Newton ... Equation (1) is the mathematical realization of this ...

  7. AC losses in HTS coils for high-frequency and non-sinusoidal currents

    Science.gov (United States)

    de Bruyn, B. J. H.; Jansen, J. W.; Lomonova, E. A.

    2017-09-01

    AC losses in racetrack coils that are wound of YBCO tapes are measured for sinusoidal and non-sinusoidal transport currents with fundamental frequencies up to 1 kHz. An electrical method to measure losses for non-sinusoidal currents is developed for this purpose. The measured losses are compared to the losses calculated by 2D finite element models with power-law material models. The frequency and waveform-dependency of the measured losses are shown and compared to the results of the models over a wide range of frequencies and waveforms. Finally, it is shown that the finite element models can accurately predict AC losses resulting from non-sinusoidal transport currents as are present in highly dynamic motors with AC armature coils.

  8. The effects of theta transcranial alternating current stimulation (tACS) on fluid intelligence.

    Science.gov (United States)

    Pahor, Anja; Jaušovec, Norbert

    2014-09-01

    The objective of the study was to explore the influence of transcranial alternating current stimulation (tACS) on resting brain activity and on measures of fluid intelligence. Theta tACS was applied to the left parietal and left frontal brain areas of healthy participants after which resting electroencephalogram (EEG) data was recorded. Following sham/active stimulation, the participants solved two tests of fluid intelligence while their EEG was recorded. The results showed that active theta tACS affected spectral power in theta and alpha frequency bands. In addition, active theta tACS improved performance on tests of fluid intelligence. This influence was more pronounced in the group of participants that received stimulation to the left parietal area than in the group of participants that received stimulation to the left frontal area. Left parietal tACS increased performance on the difficult test items of both tests (RAPM and PF&C) whereas left frontal tACS increased performance only on the easy test items of one test (RAPM). The observed behavioral tACS influences were also accompanied by changes in neuroelectric activity. The behavioral and neuroelectric data tentatively support the P-FIT neurobiological model of intelligence.

  9. A Series-LC-Filtered Active Damper for AC Power Electronics Based Power Systems

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

    2015-01-01

    This paper proposes an active damper with a series LC-filter for suppressing resonances in an ac power electronics based power system. The added filter capacitor helps to lower the voltage stress of the converter to be used for implementing the damper. Unlike active filters for the compensation...... is built, where the damper is integrated into a grid-connected converter. The results obtained from the experiments demonstrate the stability enhancement of ac power electronics based power systems by the active damper....

  10. AC losses in superconductors with a power-law constitutive relation

    Energy Technology Data Exchange (ETDEWEB)

    Agassi, Y.D., E-mail: yehoshua.agassi@navy.mil

    2015-10-15

    Highlights: • Derivation of power-law constitutive-relation from distributed Anderson–Kim theory. • The electric-field for HTS constitutive-relation satisfies nonlinear heat-equation. • For slab, AC losses scale as B{sub 0}{sup m}, m = 3–4 and I{sup 3} with field-amplitude and current, respectively. • Calculated pinning potential, AC-losses scaling is consistent with BSCCO data. - Abstract: The observed constitutive relation between the electrical field and current density in cuprates high temperature superconductors is a power-law of the current. This functional dependence is presumably related to the giant flux-creep domain. It is shown that this constitutive relation reflects the statistical spread of the pinning potential associated with creep motion of vortex bundles. The AC losses emanating from a power-law constitutive relation are calculated in an approach focused on the superconductor’s electric field. For a slab geometry in the presence of a parallel AC magnetic field or transport current, the calculated AC-loss scaling laws are consistent with BSCCO data and the critical state model. Extensions of the approach are briefly discussed.

  11. Transcranial Alternating Current Stimulation (tACS) Enhances Mental Rotation Performance during and after Stimulation

    Science.gov (United States)

    Kasten, Florian H.; Herrmann, Christoph S.

    2017-01-01

    Transcranial alternating current stimulation (tACS) has been repeatedly demonstrated to modulate endogenous brain oscillations in a frequency specific manner. Thus, it is a promising tool to uncover causal relationships between brain oscillations and behavior or perception. While tACS has been shown to elicit a physiological aftereffect for up to 70 min, it remains unclear whether the effect can still be elicited if subjects perform a complex task interacting with the stimulated frequency band. In addition, it has not yet been investigated whether the aftereffect is behaviorally relevant. In the current experiment, participants performed a Shepard-like mental rotation task for 80 min. After 10 min of baseline measurement, participants received either 20 min of tACS at their individual alpha frequency (IAF) or sham stimulation (30 s tACS in the beginning of the stimulation period). Afterwards another 50 min of post-stimulation EEG were recorded. Task performance and EEG were acquired during the whole experiment. While there were no effects of tACS on reaction times or event-related-potentials (ERPs), results revealed an increase in mental rotation performance in the stimulation group as compared to sham both during and after stimulation. This was accompanied by increased ongoing alpha power and coherence as well as event-related-desynchronization (ERD) in the alpha band in the stimulation group. The current study demonstrates a behavioral and physiological aftereffect of tACS in parallel. This indicates that it is possible to elicit aftereffects of tACS during tasks interacting with the alpha band. Therefore, the tACS aftereffect is suitable to achieve an experimental manipulation. PMID:28197084

  12. Introducing AC Inductive Reactance with a Power Tool

    Science.gov (United States)

    Bryant, Wesley; Baker, Blane

    2016-01-01

    The concept of reactance in AC electrical circuits is often non-intuitive and difficult for students to grasp. In order to address this lack of conceptual understanding, classroom exercises compare the predicted resistance of a power tool, based on electrical specifications, to measured resistance. Once students discover that measured resistance…

  13. Total loss of AC power analysis for EPR reactor

    Energy Technology Data Exchange (ETDEWEB)

    Darnowski, Piotr, E-mail: piotr.darnowski@itc.pw.edu.pl [Warsaw University of Technology, Institute of Heat Engineering, Nowowiejska 21/25, 00-665 Warsaw (Poland); Skrzypek, Eleonora, E-mail: eleonora.skrzypek@ncbj.gov.pl [Warsaw University of Technology, Institute of Heat Engineering, Nowowiejska 21/25, 00-665 Warsaw (Poland); National Centre for Nuclear Research (NCBJ), A. Sołtana 7, 05-400 Otwock-Świerk (Poland); Mazgaj, Piotr, E-mail: piotr.mazgaj@itc.pw.edu.pl [Warsaw University of Technology, Institute of Heat Engineering, Nowowiejska 21/25, 00-665 Warsaw (Poland); Świrski, Konrad [Warsaw University of Technology, Institute of Heat Engineering, Nowowiejska 21/25, 00-665 Warsaw (Poland); Gandrille, Pascal [AREVA NP SAS, Tour AREVA, 1 place Jean Millier, 92084 Paris La Défense (France)

    2015-08-15

    Highlights: • Total loss of AC power (Station Blackout) was simulated for the EPR reactor model. • In-vessel phase of the accident is under consideration. • Comparison of MELCOR and MAAP results is presented. • MELCOR and MAAP results are comparable. - Abstract: In this paper the results of severe accident simulations for the EPR reactor in the case of loss of offsite power combined with total failure of all diesel generators (total loss of AC power) are presented. Calculations were performed with MELCOR 2.1 computer code for in-vessel phase of the accident. In this scenario, the unavailability of all offsite and onsite power sources and the lack of cooling leads directly to core degradation, material relocation to the lower plenum and rupture of the reactor pressure vessel. MELCOR results were compared qualitatively and quantitatively with MAAP4 code results and show a good agreement.

  14. Photovoltaic Inverter Controllers Seeking AC Optimal Power Flow Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Dall' Anese, Emiliano; Dhople, Sairaj V.; Giannakis, Georgios B.

    2016-07-01

    This paper considers future distribution networks featuring inverter-interfaced photovoltaic (PV) systems, and addresses the synthesis of feedback controllers that seek real- and reactive-power inverter setpoints corresponding to AC optimal power flow (OPF) solutions. The objective is to bridge the temporal gap between long-term system optimization and real-time inverter control, and enable seamless PV-owner participation without compromising system efficiency and stability. The design of the controllers is grounded on a dual ..epsilon..-subgradient method, while semidefinite programming relaxations are advocated to bypass the non-convexity of AC OPF formulations. Global convergence of inverter output powers is analytically established for diminishing stepsize rules for cases where: i) computational limits dictate asynchronous updates of the controller signals, and ii) inverter reference inputs may be updated at a faster rate than the power-output settling time.

  15. High-power converters and AC drives

    CERN Document Server

    Wu, Bin

    2017-01-01

    This new edition reflects the recent technological advancements in the MV drive industry, such as advanced multilevel converters and drive configurations. It includes three new chapters, Control of Synchronous Motor Drives, Transformerless MV Drives, and Matrix Converter Fed Drives. In addition, there are extensively revised chapters on Multilevel Voltage Source Inverters and Voltage Source Inverter-Fed Drives. This book includes a systematic analysis on a variety of high-power multilevel converters, illustrates important concepts with simulations and experiments, introduces various megawatt drives produced by world leading drive manufacturers, and addresses practical problems and their mitigations methods.

  16. Measurement of Current Profile in a Tokamak Through AC Modulation

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The plasma current is modulated with an alternating current (ac) component in a frequency range of 90 Hz~900 Hz in the plateau discharge phase in the CT-6B tokamak. A plasma electric conductivity profile in a form of (1 - r2/a2)α with a parameter α, which is fitted with the experimental data, can be determined. The effects of magnetic shear in a tokamak field configuration on the current penetration are taken into account in the numerical simulation. The measurement method and obtained results are discussed.

  17. Engineering Design of the ITER AC/DC Power Supply System

    Energy Technology Data Exchange (ETDEWEB)

    Oh, B. H.; Lee, K. W.; Chang, D. S.; Jin, J. T.; Hwang, C. K.

    2010-02-15

    To design high power pulse power supplies, especially in huge power supplies have not designed till now, it is necessary to analyze a system's characteristics and relations with another systems as well as to know high voltage, high current control technologies. Contents of this project are; - Analysis of the changed designs of the AC/DC converters. - Setup of the PSIM model for the calculation of the junction temperature of the converter thyristors. - Finalize the converter's simulation modules and estimate the parallel number of an arm for each converter. - Fix the protection sequence and make a simulation. - Stability check of the power distribution system against the reactive power effect. - Design of small size hardware AC/DC converter. The results of these studies may used as one of references for practical designs of the power supplies and also used for developing Tokamak type fusion reactors in the future

  18. A Non-linear Controller for Single-Phase AC-AC Power Converter to meet UPS Performance Index

    Directory of Open Access Journals (Sweden)

    Abdelhafid Ait Elmahjoub

    2012-07-01

    Full Text Available This article focuses on AC-AC power converter that can be used for uninterruptible power supply (UPS. The converter is built on two stages: a AC-DC input stage and a DC-AC output stage. The two blocks are connected by an intermediate DC bus. The aim of control is threefold: i power factor correction ii regulation of DC bus iii generating a sinusoidal voltage at the output. The synthesis of controllers has been achieved through the technique of nonlinear backstepping control. A detailed analysis of the stability control system is presented. The performances of regulators have been validated by numerical simulation in MATLAB / SIMULINK.

  19. Calculation of AC loss in two-layer superconducting cable with equal currents in the layers

    Science.gov (United States)

    Erdogan, Muzaffer

    2016-12-01

    A new method for calculating AC loss of two-layer SC power transmission cables using the commercial software Comsol Multiphysics, relying on the approach of the equal partition of current between the layers is proposed. Applying the method to calculate the AC-loss in a cable composed of two coaxial cylindrical SC tubes, the results are in good agreement with the analytical ones of duoblock model. Applying the method to calculate the AC-losses of a cable composed of a cylindrical copper former, surrounded by two coaxial cylindrical layers of superconducting tapes embedded in an insulating medium with tape-on-tape and tape-on-gap configurations are compared. A good agreement between the duoblock model and the numerical results for the tape-on-gap cable is observed.

  20. DSP Based Control Implementation of an AC/DC Converter with Improved Input Current Distortion

    Directory of Open Access Journals (Sweden)

    WISUTMETHEEKORN, P.

    2011-05-01

    Full Text Available This paper presents a digital signal processor based control of an AC/DC converter with nearly unity power factor. Normally, the output voltage of a single-phase AC/DC converter comprises a voltage ripple with twice line-frequency. This affects the voltage control loop and leads to the converter input current distortion. The purposed method is designed to avoid the effect of the output voltage ripple. To verify the proposed control method, MATLAB/Simulink is used for system simulation. A hardware prototype is setup. A low cost digital signal processing chip dsPIC30F4011 is employed as a digital controller to control a CUK AC/DC converter. The converter specifications are 48V output voltage and 250W output power. From the simulation and the experimental results shown that the input current distortion of the purposed system is reduced and lower than the AC/DC converter that controlled by the conventional proportional-integral controller.

  1. Input current shaped ac-to-dc converters

    Science.gov (United States)

    1985-01-01

    Input current shaping techniques for ac-to-dc converters were investigated. Input frequencies much higher than normal, up to 20 kHz were emphasized. Several methods of shaping the input current waveform in ac-to-dc converters were reviewed. The simplest method is the LC filter following the rectifier. The next simplest method is the resistor emulation approach in which the inductor size is determined by the converter switching frequency and not by the line input frequency. Other methods require complicated switch drive algorithms to construct the input current waveshape. For a high-frequency line input, on the order of 20 kHz, the simple LC cannot be discarded so peremptorily, since the inductor size can be compared with that for the resistor emulation method. In fact, since a dc regulator will normally be required after the filter anyway, the total component count is almost the same as for the resistor emulation method, in which the filter is effectively incorporated into the regulator.

  2. Modeling and Analysis of Harmonic Stability in an AC Power-Electronics-Based Power System

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Wu, Weimin

    2014-01-01

    This paper addresses the harmonic stability caused by the interactions among the wideband control of power converters and passive components in an AC power-electronicsbased power system. The impedance-based analytical approach is employed and expanded to a meshed and balanced threephase network...

  3. Interior point algorithm-based power flow optimisation of a combined AC and DC multi-terminal grid

    Directory of Open Access Journals (Sweden)

    Farhan Beg

    2015-01-01

    Full Text Available The high cost of power electronic equipment, lower reliability and poor power handling capacity of the semiconductor devices had stalled the deployment of systems based on DC (multi-terminal direct current system (MTDC networks. The introduction of voltage source converters (VSCs for transmission has renewed the interest in the development of large interconnected grids based on both alternate current (AC and DC transmission networks. Such a grid platform also realises the added advantage of integrating the renewable energy sources into the grid. Thus a grid based on DC MTDC network is a possible solution to improve energy security and check the increasing supply demand gap. An optimal power solution for combined AC and DC grids obtained by the solution of the interior point algorithm is proposed in this study. Multi-terminal HVDC grids lie at the heart of various suggested transmission capacity increases. A significant difference is observed when MTDC grids are solved for power flows in place of conventional AC grids. This study deals with the power flow problem of a combined MTDC and an AC grid. The AC side is modelled with the full power flow equations and the VSCs are modelled using a connecting line, two generators and an AC node. The VSC and the DC losses are also considered. The optimisation focuses on several different goals. Three different scenarios are presented in an arbitrary grid network with ten AC nodes and five converter stations.

  4. Impacts on Power Factor of AC Voltage Controllers Under Non-Sinusoidal Conditions

    Directory of Open Access Journals (Sweden)

    Mukhtiar Ahmed Mahar

    2012-04-01

    Full Text Available AC-AC conversion is obtained with the help of Cyclo-converters, DC Link converters and AC Voltage Controllers. AC voltage controllers are also referred to as voltage regulators. Main issue concerned to these converters is that they generate harmonics due to periodic variable structure system. The generated harmonics create disturbances and degrade the performance of converter. The power factor of supply side is affected due to these harmonics. This paper focuses on source side power factor of ac voltage controllers under nonsinusoidal conditions. In order to observe the power factor, measurement tool of power factor and simulation model of ac voltage controller is also developed in MATLAB software.

  5. 21 CFR 880.5100 - AC-powered adjustable hospital bed.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered adjustable hospital bed. 880.5100... (CONTINUED) MEDICAL DEVICES GENERAL HOSPITAL AND PERSONAL USE DEVICES General Hospital and Personal Use Therapeutic Devices § 880.5100 AC-powered adjustable hospital bed. (a) Identification. An AC-powered...

  6. Study of Power Flow Algorithm of AC/DC Distribution System including VSC-MTDC

    Directory of Open Access Journals (Sweden)

    Haifeng Liang

    2015-08-01

    Full Text Available In recent years, distributed generation and a large number of sensitive AC and DC loads have been connected to distribution networks, which introduce a series of challenges to distribution network operators (DNOs. In addition, the advantages of DC distribution networks, such as the energy conservation and emission reduction, mean that the voltage source converter based multi-terminal direct current (VSC-MTDC for AC/DC distribution systems demonstrates a great potential, hence drawing growing research interest. In this paper, considering losses of the reactor, the filter and the converter, a mathematical model of VSC-HVDC for the load flow analysis is derived. An AC/DC distribution network architecture has been built, based on which the differences in modified equations of the VSC-MTDC-based network under different control modes are analyzed. In addition, corresponding interface functions under five control modes are provided, and a back/forward iterative algorithm which is applied to power flow calculation of the AC/DC distribution system including VSC-MTDC is proposed. Finally, by calculating the power flow of the modified IEEE14 AC/DC distribution network, the efficiency and validity of the model and algorithm are evaluated. With various distributed generations connected to the network at appropriate locations, power flow results show that network losses and utilization of transmission networks are effectively reduced.

  7. Motor power control circuit for ac induction motors

    Science.gov (United States)

    Nola, F. J. (Inventor)

    1983-01-01

    A motor power control of the type which functions by controlling the power factor wherein one of the parameters of power factor current on time is determined by the on time of a triac through which current is supplied to the motor. By means of a positive feedback circuit, a wider range of control is effected.

  8. High Voltage AC underground cable systems for power transmission

    DEFF Research Database (Denmark)

    Bak, Claus Leth; Silva, Filipe Miguel Faria da

    2016-01-01

    This paper is a second of two presenting a review of research results in underground cable transmission obtained by the Department of Energy Technology, Aalborg University ET/AAU and Danish TSO Energinet.dk within the last six years. The main core of the results are obtained by PhD students...... researching electrical engineering topics related to using underground cables for power transmission at EHV level and including the 420 kV level. The research topics were laid down by ET/AAU and Energinet.dk in the DANPAC (DANish Power systems with Ac Cables) research project. The main topics are discussed...

  9. A Multi-channel AC Power Supply Controller

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A multi-channel AC power Supply controler developed recently by us was introdueed briefty in this paper.This controller is a computer controlled multi-electronic-switch device.The controller contains 16 independent channels in a standard box(440W×405D×125H mm).There is an electronic switch in each channel,the rated load power is≤1 kW.The main function of the controller is to set the state of electronic switch(ON/OFF)

  10. Power factor control system for ac induction motors

    Science.gov (United States)

    Nola, F. J. (Inventor)

    1981-01-01

    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.

  11. AC Power Supply for Wobbler Magnet of the MC-50 Cyclotron

    CERN Document Server

    Kim, Yu-Seok; Kang, Bong-Koo; Lee, Hong-Gi; Park, Ki-Hyeon; Wha Chung, Chin; Woo Lee, Wol

    2005-01-01

    The MC-50 cyclotron (k=50) produces the ion beam for nuclear physics, chemistry, and applied researches in Korea. It has a small beam diameter with Gaussian beam shape, whereas many users want a beam irradiation on a large target. A wobbler magnet and an AC power supply were designed and constructed to meet the users' requirement. The power supply has two independently operating channels for the vertical and horizontal coils of the wobbler magnet. The frequency of the AC power supply for both coils is programmable from 1 to 20 Hz in a step of 1 Hz, and the maximum rms output current is 12 A. Various properties of the power supply and experimental results are given in the paper.

  12. SOLAR TO AC POWER SOURCE FOR REMOTE AREAS USING SEIG

    Directory of Open Access Journals (Sweden)

    MEHMET AKBABA

    2012-02-01

    Full Text Available Photovoltaic generators (PVG are increasingly used to provide electricity in remote areas. However, in many applications the DC generated electricity by a PVG need to be converted to AC. Traditionally DC to AC inverters have been widely used for this purpose. In this paper, a different system is proposed in which a self excited induction generator (SEIG driven by a permanent magnet DC motor (DCM and powered from a PVG through a maximum power point tracker (MPPT are used. A step-up chopper is utilized as an MPPT unit. The proposed system is modelled in time domain, and a detailed transient and steady-state analysis are presented. The main reason behind analyzing the system in the time domain is because of the fact that for unknown speeds, the methods developed for steady-state analysis of SEIGs can not be applied. The presented work shows that the full available power of the PVG can be harnessed by selecting suitable values for the duty cycle and the frequency of the step up chopper and the excitation capacitor of the SEIG. It is also shown that with such a combination power utilization efficiency of more than 83% can be achieved.

  13. Critical current density measurement of thin films by AC susceptibility based on the penetration parameter h

    Energy Technology Data Exchange (ETDEWEB)

    Li Xiaofen, E-mail: xiaofenli@gmail.com [Materials Research Division, Riso National Laboratory for Sustainable Energy, Technical University of Denmark, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Grivel, Jean-Claude; Abrahamsen, Asger B.; Andersen, Niels H. [Materials Research Division, Riso National Laboratory for Sustainable Energy, Technical University of Denmark, Frederiksborgvej 399, DK-4000 Roskilde (Denmark)

    2012-07-15

    We have numerically proved that the dependence of AC susceptibility {chi} of a E(J) power law superconducting thin disc on many parameters can be reduced to one penetration parameter h, with E the electric field and J the current density. Based on this result, we propose a way of measuring the critical current density J{sub c} of superconducting thin films by AC susceptibility. Compared with the normally used method based on the peak of the imaginary part, our method uses a much larger range of the AC susceptibility curve, thus allowing determination of the temperature (T) dependence of J{sub c} from a normally applied {chi}(T) measurement. A fitting equation J{sub c} = 1.9H{sub a} Divides {chi} Prime Divides {sup 0.69}/d, -0.4 < {chi} Prime < -0.001 derived from the critical state case (Bean model) can be used in most situations, where H{sub a} is the amplitude of the applied AC field, {chi} Prime is the real part of the normalized susceptibility and d is the thickness of the film. The method is valid for the cases where the film is fully penetrated. We also discuss how the finite London penetration depth affects the susceptibility when the film is screened. Measurements with varying T, H{sub a} and DC background field H{sub dc} are performed to support the arguments.

  14. Critical current density measurement of thin films by AC susceptibility based on the penetration parameter h

    Science.gov (United States)

    Li, Xiao-Fen; Grivel, Jean-Claude; Abrahamsen, Asger B.; Andersen, Niels H.

    2012-07-01

    We have numerically proved that the dependence of AC susceptibility χ of a E(J) power law superconducting thin disc on many parameters can be reduced to one penetration parameter h, with E the electric field and J the current density. Based on this result, we propose a way of measuring the critical current density Jc of superconducting thin films by AC susceptibility. Compared with the normally used method based on the peak of the imaginary part, our method uses a much larger range of the AC susceptibility curve, thus allowing determination of the temperature (T) dependence of Jc from a normally applied χ(T) measurement. A fitting equation Jc = 1.9Ha∣χ‧∣0.69/d, -0.4 Bean model) can be used in most situations, where Ha is the amplitude of the applied AC field, χ‧ is the real part of the normalized susceptibility and d is the thickness of the film. The method is valid for the cases where the film is fully penetrated. We also discuss how the finite London penetration depth affects the susceptibility when the film is screened. Measurements with varying T, Ha and DC background field Hdc are performed to support the arguments.

  15. Power-supply-operations group-training programs, ac/dc power systems and micellaneous information

    Energy Technology Data Exchange (ETDEWEB)

    Harris, C A

    1978-06-30

    This program introduces the technician to three phase a-c power and its relationship to rectifier power conversion systems. A brief introduction is given as to the engineering significance of various parameters such as, phase rotation, ac power relationships, harmonics, transformer voltage vectors, rectifier parameters, filters, water cooling, phase delayed triggers to SCR's, dielectric stress vs life and other related subjects. The significance of the details as they apply to various diagnostic problems that a technician may be called upon to solve is emphasized. Reference CAPE-2747.

  16. Isolated single-stage high power factor AC/DC converter

    Institute of Scientific and Technical Information of China (English)

    王卫; 贲洪奇; 高国安

    2001-01-01

    The problem of harmonic pollution has brought wide attention with the increase of power customers. The adoption of the technology of active power factor correction (APFC) with advanced high frequency power converter is a more efficient solution to the problem of harmonic pollution. A single-stage isolated high power factor AC/DC converter, which features wide range DC output, high power factor, lower harmonic pollution in input current, and phase-shift PWM full-bridge circuit can achieve soft switching. The principle of the circuit topology and the reasons of voltage surges across the power switch are analyzed. Experiment results illustrate that this circuit has the advantages of high power factor and lower harmonic distortion.

  17. A novel wireless power and data transmission AC to DC converter for an implantable device.

    Science.gov (United States)

    Liu, Jhao-Yan; Tang, Kea-Tiong

    2013-01-01

    This article presents a novel AC to DC converter implemented by standard CMOS technology, applied for wireless power transmission. This circuit combines the functions of the rectifier and DC to DC converter, rather than using the rectifier to convert AC to DC and then supplying the required voltage with regulator as in the transitional method. This modification can reduce the power consumption and the area of the circuit. This circuit also transfers the loading condition back to the external circuit by the load shift keying(LSK), determining if the input power is not enough or excessive, which increases the efficiency of the total system. The AC to DC converter is fabricated with the TSMC 90nm CMOS process. The circuit area is 0.071mm(2). The circuit can produce a 1V DC voltage with maximum output current of 10mA from an AC input ranging from 1.5V to 2V, at 1MHz to 10MHz.

  18. The effect of 10 Hz transcranial alternating current stimulation (tACS on corticomuscular coherence

    Directory of Open Access Journals (Sweden)

    Claudia eWach

    2013-08-01

    Full Text Available Synchronous oscillatory activity at alpha (8-12 Hz, beta (13-30 Hz, and gamma (30-90 Hz fre-quencies is assumed to play a key role for motor control. Corticomuscular coherence (CMC represents an established measure of the pyramidal system’s integrity. Transcranial alternating current stimulation (tACS offers the possibility to modulate ongoing oscillatory activity. Behaviourally, 20 Hz tACS in healthy subjects has been shown to result in movement slowing. However, the neurophysiological changes underlying these effects are not entirely understood yet. The present study aimed at ascertaining the effects of tACS at 10 and 20 Hz in healthy subjects on CMC and local power of the primary sensorimotor cortex. Neuromagnetic activity was recorded during isometric contraction before and at two time points (2-10 min and 30-38 min after tACS of the left primary motor cortex (M1, using a 306 channel whole head magnetoencephalo-graphy (MEG system. Additionally, electromyography (EMG of the right extensor digitorum communis (EDC muscle was measured. TACS was applied at 10 and 20 Hz, respectively, for 10 min at 1 mA. Sham stimulation served as control condition. The data suggest that 10 Hz tACS significantly reduced low gamma band CMC during isometric contraction. This implies that tACS does not necessarily cause effects at stimulation frequency. Rather, the findings suggest cross-frequency interplay between alpha and low gamma band activity modulating functional interaction between motor cortex and muscle.

  19. Optimizing efficiency on conventional transformer based low power AC/DC standby power supplies

    DEFF Research Database (Denmark)

    Nielsen, Nils

    2004-01-01

    This article describes the research results for simple and cheap methods to reduce the idle- and load-losses in very low power conventional transformer based power supplies intended for standby usage. In this case "very low power" means 50 Hz/230 V-AC to 5 V-DC@1 W. The efficiency is measured...... on two common power supply topologies designed for this power level. The two described topologies uses either a series (or linear) or a buck regulation approach. Common to the test power supplies is they either are using a standard cheap off-the-shelf transformer, or one, which are loss optimized by very...

  20. High Voltage AC underground cable systems for power transmission

    DEFF Research Database (Denmark)

    Bak, Claus Leth; Silva, Filipe Miguel Faria da

    2016-01-01

    This paper is a first of two presenting a review of research results in underground cable transmission obtained by the Department of Energy Technology, Aalborg University ET/AAU and Danish TSO Energinet.dk within the last 6 years. The main core of the results are obtained by PhD students research......This paper is a first of two presenting a review of research results in underground cable transmission obtained by the Department of Energy Technology, Aalborg University ET/AAU and Danish TSO Energinet.dk within the last 6 years. The main core of the results are obtained by PhD students...... researching electrical engineering topics related to using underground cables for power transmission at EHV level and including the 420 kV level. The research topics were laid down by ET/AAU and Energinet.dk in the DANPAC (DANish Power systems with AC Cables) research project. The main topics are discussed...

  1. 基于STC90C58的单相交流供电线路漏电流监测装置%STC90C58-based Device to Monitor Leakage Current of Single-phase AC Power Line

    Institute of Scientific and Technical Information of China (English)

    关旭俊; 谢力扬

    2014-01-01

    基于STC90C58设计了一种监测单相交流供电线路漏电流的装置。采用了微控制器和电能计量器件,可同时采集并显示单相交流供电线路相线电流、中性线电流和相线对地漏电流的幅值。可为判断漏电性质和排查漏电点提供数据支持,对提高漏电保安器的投入率、提高用电安全性、降低线损有一定的积极意义。%A device based on STC90C58 to monitor the leakage current of single-phase AC power line is designed .The device uses a micro-controller and a power energy IC ,it can simultaneously capture and display the amplitudes of the phase line current ,the neutral current and the phase-to-ground leakage current of the single-phase AC supply line .The device can determine the nature of leakage points and provide data to support the investigation ,it will have some positive significance to improve the input rate of leakage protectors and improve the security for using electricity and reduce line losses .

  2. Estimation and reduction of harmonic currents from power converters

    DEFF Research Database (Denmark)

    Asiminoaei, Lucian

    Power Electronics is entering more and more products that inevitably increase the number of non-linear loads installed on the power system. The major concern of the non-linear loads is the emission of non-sinusoidal currents in the supply. Circulation of the harmonic currents in power systems...... creates losses, thus determining overrating of the power system. Furthermore, the harmonic currents cause harmonic voltage distortion, which is detrimental for all connected equipments to the power system, such as capacitors, ac-machines, control and protection equipments, measuring devices and electronic...... power supplies. Although their design takes into account a certain level of harmonic voltage distortion, there are many real-life cases when the equipments experience abnormal operation, malfunction or failure. One such case appeared at a local company in Denmark, a Heat Power Station where due...

  3. Efficient relaxations for joint chance constrained AC optimal power flow

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Kyri; Toomey, Bridget

    2017-07-01

    Evolving power systems with increasing levels of stochasticity call for a need to solve optimal power flow problems with large quantities of random variables. Weather forecasts, electricity prices, and shifting load patterns introduce higher levels of uncertainty and can yield optimization problems that are difficult to solve in an efficient manner. Solution methods for single chance constraints in optimal power flow problems have been considered in the literature, ensuring single constraints are satisfied with a prescribed probability; however, joint chance constraints, ensuring multiple constraints are simultaneously satisfied, have predominantly been solved via scenario-based approaches or by utilizing Boole's inequality as an upper bound. In this paper, joint chance constraints are used to solve an AC optimal power flow problem while preventing overvoltages in distribution grids under high penetrations of photovoltaic systems. A tighter version of Boole's inequality is derived and used to provide a new upper bound on the joint chance constraint, and simulation results are shown demonstrating the benefit of the proposed upper bound. The new framework allows for a less conservative and more computationally efficient solution to considering joint chance constraints, specifically regarding preventing overvoltages.

  4. A new DC/AC boost transformerless converter in application of photovoltaic power generation

    DEFF Research Database (Denmark)

    Wei, Mo; Loh, Poh Chiang; Blaabjerg, Frede

    2011-01-01

    This paper presents a new DC/AC boost transformerless converter in the applications of photovoltaic (PV) power generation. A new circuit topology of single phase full bridge power inverter with additional DC/DC boost stage is proposed. The proposed topology overcomes two commonly existing...... shortcomings of transformerless PV system: namely one, the voltage generated sometimes low and insufficient to fulfill the load requirement; and two, there always leakage current flowing through parasitic capacitance between PV panel and ground. This configuration helps to boost the voltage at the PV side...

  5. 21 CFR 880.5510 - Non-AC-powered patient lift.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Non-AC-powered patient lift. 880.5510 Section 880... Devices § 880.5510 Non-AC-powered patient lift. (a) Identification. A non-AC-powered patient lift is a... patient in the horizontal or other required position from one place to another, as from a bed to a...

  6. Using a nonparametric PV model to forecast AC power output of PV plants

    OpenAIRE

    Almeida, Marcelo Pinho; Perpiñan Lamigueiro, Oscar; Narvarte Fernández, Luis

    2015-01-01

    In this paper, a methodology using a nonparametric model is used to forecast AC power output of PV plants using as inputs several forecasts of meteorological variables from a Numerical Weather Prediction (NWP) model and actual AC power measurements of PV plants. The methodology was built upon the R environment and uses Quantile Regression Forests as machine learning tool to forecast the AC power with a confidence interval. Real data from five PV plants was used to validate the methodology, an...

  7. Final design of the Korean AC/DC converters for the ITER coil power supply system

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Jong-Seok, E-mail: jsoh@nfri.re.kr [ITER Korea, National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of); Choi, Jungwan; Suh, Jae-Hak; Choi, Jihyun [ITER Korea, National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of); Lee, Lacksang; Kim, Changwoo; Park, Hyungjin; Jo, Seongman; Lee, Seungyun; Hwang, Kwangcheol; Liu, Hyoyol [Dawonsys Corp., Siheung 429-450 (Korea, Republic of); Hong, Ki-Don; Sim, Dong-Joon; Lee, Jang-Soo [Hyosung Corp., Gongdeok-Dong, Seoul 121-720 (Korea, Republic of); Lee, Eui-Jae; Kwon, Yang-Hae; Lee, Dae-Yeol; Ko, Ki-Won; Kim, Jong-Min [Mobiis Corp., Yangjae-dong, Seoul 137-888 (Korea, Republic of); Song, Inho [ITER Organization, Route de Vinon sur Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); and others

    2015-10-15

    The final design of the ITER TF, CS, CC and VS AC/DC converters has been completed to implement ITER requirements following the detailed design and refinements of the preliminary design. The number of parallel thyristors and the rating of fuses are coordinated to keep those devices within the explosion limit even under most severe fault conditions. The impedance of the converter transformer has been optimized taking into account the energization inrush current, short circuit current, reactive power consumption and the available DC voltage. To ensure system integrity, AC/DC converters are mechanically divided into transformers, AC busbars, 6-pulse bridges, DC interconnecting busbars and DC reactors, and then all subsystems are decoupled by flexible links. To provide stable real time network communication down to the converters, a one GbE link is deployed between master controllers and local controllers. IEEE 1588 is implemented to the embedded controllers for precision time synchronization. This paper describes the detailed solutions implemented in the final design for the ITER AC/DC converters with R&D results of converter prototypes.

  8. Alternating current(AC) corrosion analyzed by electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Tae Hyun; Kim, Dae Kyeong; Bae, Jeong Hyo; Lee, Hyun Goo; Lee, Sung Jin [Korea Electrotechnology Research Institute, Changwon (Korea, Republic of)

    2002-12-15

    So far, many research results on AC corrosion have been reported but each one is not consistent with another. In order to understand the characteristics and factors affecting on AC corrosion, Electrochemical impedance spectroscopy (E.I.S) was used and changes in kinetics and surface properties was analyzed. Generally, E.I.S. test has been used mainly for the diagnosis of the concrete corrosion and coating material. However, considering the outstanding functions of E.I.S. test, it can be adopted as a good method to study AC corrosion. Electrolyte resistance (R{sub sol}), double layer capacitance (C{sub dl}) and polarization resistance (R{sub p}) are the basic circuit elements. Using the model which is consist of these basic elements, various results of E.I.S. test can be interpreted. And through this method the mechanism and characteristics of AC corrosion can be explained

  9. Nonlinear control of voltage source converters in AC-DC power system.

    Science.gov (United States)

    Dash, P K; Nayak, N

    2014-07-01

    This paper presents the design of a robust nonlinear controller for a parallel AC-DC power system using a Lyapunov function-based sliding mode control (LYPSMC) strategy. The inputs for the proposed control scheme are the DC voltage and reactive power errors at the converter station and the active and reactive power errors at the inverter station of the voltage-source converter-based high voltage direct current transmission (VSC-HVDC) link. The stability and robust tracking of the system parameters are ensured by applying the Lyapunov direct method. Also the gains of the sliding mode control (SMC) are made adaptive using the stability conditions of the Lyapunov function. The proposed control strategy offers invariant stability to a class of systems having modeling uncertainties due to parameter changes and exogenous inputs. Comprehensive computer simulations are carried out to verify the proposed control scheme under several system disturbances like changes in short-circuit ratio, converter parametric changes, and faults on the converter and inverter buses for single generating system connected to the power grid in a single machine infinite-bus AC-DC network and also for a 3-machine two-area power system. Furthermore, a second order super twisting sliding mode control scheme has been presented in this paper that provides a higher degree of nonlinearity than the LYPSMC and damps faster the converter and inverter voltage and power oscillations.

  10. Measuring ac losses in superconducting cables using a resonant circuit:Resonant current experiment (RESCUE)

    DEFF Research Database (Denmark)

    Däumling, Manfred; Olsen, Søren Krüger; Rasmussen, Carsten;

    1998-01-01

    be recorded using, for example, a digital oscilloscope. The amplitude decay of the periodic voltage or current accurately reflects the power loss in the system. It consists of two components-an ohmic purely exponential one (from leads, contacts, etc.), and a nonexponential component originating from......A simple way to obtain true ac losses with a resonant circuit containing a superconductor, using the decay of the circuit current, is described. For the measurement a capacitor is short circuited with a superconducting cable. Energy in the circuit is provided by either charging up the capacitors...... with a certain voltage, or letting a de flow in the superconductor. When the oscillations are started-either by opening a switch in case a de is flowing or by closing a switch to connect the charged capacitors with the superconductor-the current (via a Rogowski coil) or the voltage on the capacitor can...

  11. Low-energy hydraulic fracturing wastewater treatment via AC powered electrocoagulation with biochar.

    Science.gov (United States)

    Lobo, Fernanda Leite; Wang, Heming; Huggins, Tyler; Rosenblum, James; Linden, Karl G; Ren, Zhiyong Jason

    2016-05-15

    Produced and flowback waters are the largest byproducts associated with unconventional oil and gas exploration and production. Sustainable and low cost technologies are needed to treat and reuse this wastewater to avoid the environmental problems associated with current management practices (i.e., deep well injection). This study presents a new process to integrate AC-powered electrocoagulation (EC) with granular biochar to dramatically reduce energy use and electrode passivation while achieving high treatment efficiency. Results show achieving a 99% turbidity and TSS removal for the AC-EC-biochar system only used 0.079 kWh/m(3) or 0.15 kWh/kg TSS, which is 70% lower than traditional DC-EC systems and orders of magnitude lower than previous studies. The amount of biochar added positively correlates with energy saving, and further studies are needed to improve organic carbon and salt removal through system integration.

  12. Introduction to electrical power and power electronics

    CERN Document Server

    Patel, Mukund R

    2012-01-01

    Power Generation, Distribution, and Utilization AC Power Fundamentals Common Aspects of Power Equipments AC Generator AC and DC Motors Transformer Power Cable Power Distribution Fault Current Analysis System ProtectionEconomic Use of PowerElectrochemical BatteryPower Electronics and Motor Drives Power Electronics Devices DC-DC Converters AC-DC-AC Converters Variable-Frequency Drives Quality of Power Power Converter CoolingAppendixIndex

  13. Transmission Technologies and Operational Characteristic Analysis of Hybrid UHV AC/DC Power Grids in China

    Science.gov (United States)

    Tian, Zhang; Yanfeng, Gong

    2017-05-01

    In order to solve the contradiction between demand and distribution range of primary energy resource, Ultra High Voltage (UHV) power grids should be developed rapidly to meet development of energy bases and accessing of large-scale renewable energy. This paper reviewed the latest research processes of AC/DC transmission technologies, summarized the characteristics of AC/DC power grids, concluded that China’s power grids certainly enter a new period of large -scale hybrid UHV AC/DC power grids and characteristics of “strong DC and weak AC” becomes increasingly pro minent; possible problems in operation of AC/DC power grids was discussed, and interaction or effect between AC/DC power grids was made an intensive study of; according to above problems in operation of power grids, preliminary scheme is summarized as fo llows: strengthening backbone structures, enhancing AC/DC transmission technologies, promoting protection measures of clean energ y accessing grids, and taking actions to solve stability problems of voltage and frequency etc. It’s valuable for making hybrid UHV AC/DC power grids adapt to operating mode of large power grids, thus guaranteeing security and stability of power system.

  14. Control of VSC-HVDC in offshore AC islands with wind power plants: Comparison of two alternatives

    DEFF Research Database (Denmark)

    Zeni, Lorenzo; Hesselbæk, Bo; Sørensen, Poul Ejnar;

    2015-01-01

    The subject of this paper is the control of offshore AC collection and export networks behind a voltage source converter based high voltage direct current transmission system. The inertia-less nature of such grids makes the control of voltages and power flows potentially more flexible, but at the...

  15. Design of Three Phase Solar-Based 4.5kw Ac Power Inverter Station

    Directory of Open Access Journals (Sweden)

    Dr.J.C. Onuegbu

    2013-07-01

    Full Text Available The design model of a 4.50Kilowatt, 3-phase, 50 hertz solar-based power generating station was examined by the paper. The power station is a dual source input generating station using 8 series connected 100A, 12V batteries per phase as backup, the solar panels being the main frame. An inverter of 12Volt direct current input voltage was incorporated to supply an output of 3-phase, 220Volts and 50 hertz alternating current. A charging circuit was installed to monitor charging level and to preserve the accumulator’s life span. The paper also looked into the solar-based power station component design model. The batteries therein are back-up and the system will ensure 24-hours reliable power supply. The setup has a normally closed switching relay ready to pickup the auxiliary battery supply within a few milliseconds after the solar source voltage drops below a stipulated level. The three phase a.c. voltage was achieved using standby on-line circuit with cascaded 741-based flip-flop at the base of the transistor drivers of the 3-phase power transformer. This model circuit reduced the load on each phase winding and facilitated reliable and uninterruptible power supply. The delta-wyeconnected transformer will guarantee proper phase shift of 120 degrees that will emulate alternating current voltage similar to the conventional generator voltage.

  16. An overview of power electronics applications in fuel cell systems: DC and AC converters.

    Science.gov (United States)

    Ali, M S; Kamarudin, S K; Masdar, M S; Mohamed, A

    2014-01-01

    Power electronics and fuel cell technologies play an important role in the field of renewable energy. The demand for fuel cells will increase as fuel cells become the main power source for portable applications. In this application, a high-efficiency converter is an essential requirement and a key parameter of the overall system. This is because the size, cost, efficiency, and reliability of the overall system for portable applications primarily depend on the converter. Therefore, the selection of an appropriate converter topology is an important and fundamental aspect of designing a fuel cell system for portable applications as the converter alone plays a major role in determining the overall performance of the system. This paper presents a review of power electronics applications in fuel cell systems, which include various topology combinations of DC converters and AC inverters and which are primarily used in fuel cell systems for portable or stand-alone applications. This paper also reviews the switching techniques used in power conditioning for fuel cell systems. Finally, this paper addresses the current problem encountered with DC converters and AC inverter.

  17. Plasma antennas driven by 5–20 kHz AC power supply

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jiansen, E-mail: 67093058@qq.com; Chen, Yuli; Sun, Yang; Wu, Huafeng; Liu, Yue; Yuan, Qiumeng [Merchant Marine College, Shanghai Maritime University, Shanghai, 201306 (China)

    2015-12-15

    The experiments described in this work were performed with the aim of introducing a new plasma antenna that was excited by a 5–20 kHz alternating current (AC) power supply, where the antenna was transformed into a U-shape. The results show that the impedance, voltage standing-wave ratio (VSWR), radiation pattern and gain characteristics of the antenna can be controlled rapidly by varying not only the discharge power, but also by varying the discharge frequency in the range from 5 to 20 kHz. When the discharge frequency is adjusted from 10 to 12 kHz, the gain is higher within a relatively broad frequency band and the switch-on time is less than 1 ms when the discharge power is less than 5 W, meaning that the plasma antenna can be turned on and off rapidly.

  18. Modeling and analysis of harmonic resonance in a power electronics based AC power system

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe

    2013-01-01

    The dynamic interactions among the interconnected power converters may bring in harmonic resonance in a power electronics based power system. This paper addresses this issue in a power system dominated by multiple current- and voltage-controlled inverters with LCL- and LC-filters. The impedance-b...

  19. DC Voltage Droop Control Implementation in the AC/DC Power Flow Algorithm: Combinational Approach

    DEFF Research Database (Denmark)

    Akhter, F.; Macpherson, D.E.; Harrison, G.P.

    2015-01-01

    In this paper, a combinational AC/DC power flow approach is proposed for the solution of the combined AC/DC network. The unified power flow approach is extended to include DC voltage droop control. In the VSC based MTDC grids, DC droop control is regarded as more advantageous in terms...... of operational flexibility, as more than one VSC station controls the DC link voltage of the MTDC system. This model enables the study of the effects of DC droop control on the power flows of the combined AC/DC system for steady state studies after VSC station outages or transient conditions without needing...... to use its complete dynamic model. Further, the proposed approach can be extended to include multiple AC and DC grids for combined AC/DC power flow analysis. The algorithm is implemented by modifying the MATPOWER based MATACDC program and the results shows that the algorithm works efficiently....

  20. Mapping entrained brain oscillations during transcranial alternating current stimulation (tACS)

    NARCIS (Netherlands)

    Witkowski, M.; Garcia Cossio, E.; Chander, B.S.; Braun, C.; Birbaumer, N.; Robinson, S.E.; Soekadar, S.R.

    2016-01-01

    Transcranial alternating current stimulation (tACS), a non-invasive and well-tolerated form of electric brain stimulation, can influence perception, memory, as well as motor and cognitive function. While the exact underlying neurophysiological mechanisms are unknown, the effects of tACS are mainly

  1. Power flow analysis for droop controlled LV hybrid AC-DC microgrids with virtual impedance

    DEFF Research Database (Denmark)

    Li, Chendan; Chaudhary, Sanjay; Vasquez, Juan Carlos

    2014-01-01

    The AC-DC hybrid microgrid is an effective form of utilizing different energy resources and the analysis of this system requires a proper power flow algorithm. This paper proposes a suitable power flow algorithm for LV hybrid AC-DC microgrid based on droop control and virtual impedance. Droop...... and virtual impedance concepts for AC network, DC network and interlinking converter are reviewed so as to model it in the power flow analysis. The validation of the algorithm is verified by comparing it with steady state results from detailed time domain simulation. The effectiveness of the proposed...

  2. AC losses in monofilamentary MgB{sub 2} round wire carrying alternating transport currents

    Energy Technology Data Exchange (ETDEWEB)

    Kajikawa, K [Research Institute of Superconductor Science and Systems, Kyushu University, Fukuoka 819-0395 (Japan); Kawano, T [Department of Electrical and Electronic Systems Engineering, Kyushu University, Fukuoka 819-0395 (Japan); Osaka, R [Department of Electrical Engineering, Kyushu University, Fukuoka 819-0395 (Japan); Nakamura, T [Department of Electrical Engineering, Kyoto University, Kyoto 615-8510 (Japan); Sugano, M [Department of Electronic Science and Engineering, Kyoto University, Kyoto 615-8510 (Japan); Takahashi, M; Wakuda, T, E-mail: kajikawa@sc.kyushu-u.ac.j [Hitachi Research Laboratory, Hitachi, Ltd, Hitachi 319-1292 (Japan)

    2010-04-15

    AC losses in a monofilamentary MgB{sub 2} round wire with niobium and copper metal sheaths and carrying alternating transport currents are evaluated at several temperatures and frequencies. First, the transport current losses are observed electrically using a lock-in amplifier. Experimental results show that the AC losses decrease with an increase in the temperature if the amplitude of the transport current normalized by the corresponding critical current is maintained constant. On the other hand, the AC losses increase slightly with the frequency. Next, the AC losses are calculated numerically by a finite difference method. The numerical results for the superconductor filament show a good agreement with the results of the conventional theoretical expression formulated using the Bean model over a wide range of current amplitudes. It is also found that the AC losses in the niobium sheath are negligible whereas those in the copper sheath are comparable with those in the superconductor. On the basis of the numerical calculations, an expression is analytically derived for estimating the eddy current loss occurring in a metal sheath. The derived expression well reproduces the AC loss properties of both the copper and niobium sheaths.

  3. AC losses in monofilamentary MgB2 round wire carrying alternating transport currents

    Science.gov (United States)

    Kajikawa, K.; Kawano, T.; Osaka, R.; Nakamura, T.; Sugano, M.; Takahashi, M.; Wakuda, T.

    2010-04-01

    AC losses in a monofilamentary MgB2 round wire with niobium and copper metal sheaths and carrying alternating transport currents are evaluated at several temperatures and frequencies. First, the transport current losses are observed electrically using a lock-in amplifier. Experimental results show that the AC losses decrease with an increase in the temperature if the amplitude of the transport current normalized by the corresponding critical current is maintained constant. On the other hand, the AC losses increase slightly with the frequency. Next, the AC losses are calculated numerically by a finite difference method. The numerical results for the superconductor filament show a good agreement with the results of the conventional theoretical expression formulated using the Bean model over a wide range of current amplitudes. It is also found that the AC losses in the niobium sheath are negligible whereas those in the copper sheath are comparable with those in the superconductor. On the basis of the numerical calculations, an expression is analytically derived for estimating the eddy current loss occurring in a metal sheath. The derived expression well reproduces the AC loss properties of both the copper and niobium sheaths.

  4. Evolution of beam losses after a power cut of the SR7 AC supply

    CERN Document Server

    GOMEZ ALONSO, A

    2009-01-01

    Magnet failures in the LHC could lead to equipment damage if the energy stored in the accelerator was not discharged properly. The Machine Protection Systems (MPS) ensure this proper discharge and knowledge about the evolution of losses in case of failure is needed to evaluate the adequacy of the protection. A power cut of the AC supply in SR7 would lead to a simultaneous current decay in three normal conducting circuits. The evolution of the losses after such failure is slow, with a loss time constant of more than 100 ms both at 450 GeV and 7 TeV, and in both cases the damage level is not reached before 45 ms. This leaves sufficient time for the MPS to ensure redundant protection. A similar scenario would be expected for a power cut at SR3.

  5. A Novel Active Bouncer System for Klystron Modulators with Constant AC Power Consumption

    CERN Document Server

    Cabaleiro Magallanes, F; Viarouge, P; Cros, J; De Almeida Martins, C

    2014-01-01

    This paper presents the principles and design methodologies of a novel active bouncer system, to be implemented in a transformer-based klystron modulator, which is able to meet two different objectives: 1. Regulate the output pulse voltage flattop, and 2. Attenuate the power fluctuation withdrawn from the AC network. This solution allows the utilization of a standard constant voltage / constant current power supply as a capacitor charger. The solution consists of a 4-quadrant switching converter placed in series with the main capacitor bank (forming a unique element in parallel with the capacitor charger), controlled with specific feed-back loops to achieve the two objectives. The complete design method, including a numerical optimization, of the whole system, is presented in the paper. Analyses of the compromises between the active bouncer specifications and the other modulator sub-components design is presented as well.

  6. High Precision Current Measurement for Power Converters

    CERN Document Server

    Cerqueira Bastos, M

    2015-01-01

    The accurate measurement of power converter currents is essential to controlling and delivering stable and repeatable currents to magnets in particle accelerators. This paper reviews the most commonly used devices for the measurement of power converter currents and discusses test and calibration methods.

  7. MODES OF OPERATION OF THE SYSTEM OF TRACTION POWER AC USING REACTIVE POWER COMPENSATION DEVICES

    Directory of Open Access Journals (Sweden)

    I.V. Domanskyi

    2015-06-01

    Full Text Available The paper presents a systematic analysis of existing methods of reactive power compensation. The study of operating modes of the systems external and traction power supply is carried out. The methodology for selecting promising compensation schemes and energy-saving in the traction networks AC electrified railway lines is offered. The comparative evaluation of prospective controlled compensation devices shows that use of seamlessly adjustable devices with unregulated condensing the battery and with parallel translator regulated with thyristor unit and with filters to reduce harmonics bond to the large capital investments. For traction networks of domestic railways payback period is more than 10-15 years. The most promising for traction power supply today is a stepwise adjustable devices of reactive power compensation. For the efficient allocation of investments in programs and projects of modernization of system traction power supply developed by the methodology of selecting parameters and places placement devices transverse compensation in the system traction power supply, which is based on the use of software systems with imitation of interconnected instant circuits moving loads of electric rolling stock. Based on the results of multiple calculations full factor experiment when simulating work of the systems traction power supply during the day marked the most influencing factors on energy-saving in process freight on electric traction and established the extent of their influence. These include the overflows of power, the resistance of traction network, reactive power compensation, power supply circuits and the organization of trains. Innovative technologies energy-saving railways from positions of consideration their close connection with the systems external power supply are proposed.

  8. The Topological AC and HMW Effects, and the Dual Current in 2+1 Dimensions

    CERN Document Server

    He, X G; He, Xiao-Gang

    2001-01-01

    We study the Aharonov-Casher (AC) effect and the related He-McKellar-Wilkens (HMW) effect in 2+1 dimensions. In this restricted space these effects are the result of the interaction of the electromagnetic field tensor with the dual of a current. Transferring the dual operation from the current to the field tensor shows that %these effects are this interaction may be reinterpreted as due to the interaction of an effective vector potential and a current, and the AC and HMW effects follow immediately. A general proof of this for particles with an arbitrary spin is provided. The restriction to 2+1 dimensions, with this interpretation, provides a unified way of treating the AC and HMW effects for an arbitrary spin. Perhaps more interestingly the treatment shows that a spin-0 particle can show AC and HMW effects, although it has no magnetic or electric dipole moment in the usual sense.

  9. Intertied ac–ac microgrids with autonomous power import and export

    DEFF Research Database (Denmark)

    Nutkani, Inam Ullah; Loh, Poh Chiang; Wang, Peng

    2015-01-01

    Intertied ac–ac microgrids offer many potential benefits like flexible frequency and voltage selection, reserve sharing and enhanced supply reliability. Operating them is however challenging due to their larger size and presence of more power converters with different responsibilities. These comp......Intertied ac–ac microgrids offer many potential benefits like flexible frequency and voltage selection, reserve sharing and enhanced supply reliability. Operating them is however challenging due to their larger size and presence of more power converters with different responsibilities...

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

    Science.gov (United States)

    Cormier, R.

    1990-01-01

    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.

  11. Mathematical model for the power supply system of an autonomous object with an AC power transmission over a cable rope

    Science.gov (United States)

    Rulevskiy, V. M.; Bukreev, V. G.; Shandarova, E. B.; Kuleshova, E. O.; Shandarov, S. M.; Vasilyeva, Yu Z.

    2017-02-01

    A modeling problem of the power system, which provides an AC power transmission to a submersible device over the conducting rope, was considered. The power supply system units and their parameters are described. The system multi-dimensional mathematical model in the variables state space with regard to the nonlinear characteristic of system elements is proposed.

  12. Finite element modelling of electric currents in AC submerged arc furnaces

    CSIR Research Space (South Africa)

    Mc Dougall, I

    2007-01-01

    Full Text Available . ANSYS/Multiphysics was used to predict the current density distribution in the electrodes, raw material, slag and molten metal as a result of the three phases AC current. The effect of the electrode immersion on the current path was studied...

  13. Power spectra of currents off Bombay

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    Current measurements were carried out using a recording current meter across the continental shelf off Bombay, Maharashtra, India at 4 stations from an anchored ship. Power spectra were computed for selected lengths of records. Spectral energy...

  14. Improved Design Methods for Robust Single- and Three-Phase ac-dc-ac Power Converters

    DEFF Research Database (Denmark)

    Qin, Zian

    becomes a emerging challenge. Accordingly, installation of sustainable power generators like wind turbines and solar panels has experienced a large increase during the last decades. Meanwhile, power electronics converters, as interfaces in electrical system, are delivering approximately 80 % electricity...

  15. Efficient Lightweight AC-AC Power Control for Solar UAV Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A highly efficient and lightweight dual bridge matrix power controller development is proposed that will provide high performance to a solar powered high altitude...

  16. Advanced power electronics converters PWM converters processing AC voltages

    CERN Document Server

    dos Santos, Euzeli

    2014-01-01

    This book covers power electronics, in depth, by presenting the basic principles and application details, which can be used both as a textbook and reference book.  Introduces a new method to present power electronics converters called Power Blocks Geometry. Applicable for courses focusing on power electronics, power electronics converters, and advanced power converters. Offers a comprehensive set of simulation results to help understand the circuits presented throughout the book

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

    Science.gov (United States)

    Öberg, Tomas; Peltola, Pasi

    2009-12-01

    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.

  18. A Sufficient Condition on Convex Relaxation of AC Optimal Power Flow in Distribution Networks

    DEFF Research Database (Denmark)

    Huang, Shaojun; Wu, Qiuwei; Wang, Jianhui;

    2016-01-01

    This paper proposes a sufficient condition for the convex relaxation of AC Optimal Power Flow (OPF) in radial distribution networks as a second order cone program (SOCP) to be exact. The condition requires that the allowed reverse power flow is only reactive or active, or none. Under the proposed...... sufficient condition, the feasible sub-injection region (power injections of nodes excluding the root node) of the AC OPF is convex. The exactness of the convex relaxation under the proposed condition is proved through constructing a group of monotonic series with limits, which ensures that the optimal...... solution of the SOCP can be converted to an optimal solution of the original AC OPF. The efficacy of the convex relaxation to solve the AC OPF is demonstrated by case studies of an optimal multi-period planning problem of electric vehicles (EVs) in distribution networks....

  19. A Sufficient Condition on Convex Relaxation of AC Optimal Power Flow in Distribution Networks

    DEFF Research Database (Denmark)

    Huang, Shaojun; Wu, Qiuwei; Wang, Jianhui

    2016-01-01

    This paper proposes a sufficient condition for the convex relaxation of AC Optimal Power Flow (OPF) in radial distribution networks as a second order cone program (SOCP) to be exact. The condition requires that the allowed reverse power flow is only reactive or active, or none. Under the proposed...... sufficient condition, the feasible sub-injection region (power injections of nodes excluding the root node) of the AC OPF is convex. The exactness of the convex relaxation under the proposed condition is proved through constructing a group of monotonic series with limits, which ensures that the optimal...... solution of the SOCP can be converted to an optimal solution of the original AC OPF. The efficacy of the convex relaxation to solve the AC OPF is demonstrated by case studies of an optimal multi-period planning problem of electric vehicles (EVs) in distribution networks....

  20. Power Improvement of Transmission Line Using High Voltage Direct Current (Hvdc Transmission System

    Directory of Open Access Journals (Sweden)

    Lasisi, H

    2016-08-01

    Full Text Available The use of long EHV (Extremely High Voltage ac lines for the transmission of electrical energy increases the line reactance and susceptance which limits the thermal loadings on the line in order to keep sufficient margin against transient instability. With the scheme proposed in this paper, it is possible to load the lines very close to their limit with zero reactance and susceptance. The conductors are allowed to carry usual ac along with dc superimposed on it. The added dc power flow does not cause any transient instability. The scheme comprises a twelve-pulse bridge rectifier, dc-links, pulse width modulated (PSW-voltage sourced inverter (VSI and converter transformers. The master current controller is used to implement the scheme which senses ac current and regulates the dc current orders for converters online such that conductor current never exceeds its thermal limit. This paper gives the feasibility of converting a double circuit ac line into composite ac–dc power transmission line given the advantage of stability improvement, damping oscillations, voltage stabilization and reactive power compensation for ac weak buses. Simulation and experimental studies using MATLAB (Matrix Laboratory are carried out for the coordinated control as well as independent control of ac and dc power transmissions.

  1. Analysis of energy processes in pulse converters of AC electric power

    Directory of Open Access Journals (Sweden)

    Kadatsky A.F.

    2015-02-01

    Full Text Available The article presents the analysis of energy processes in switched-mode AC-AC converters of buck, boost and buck-boost types. The mathematical model of energy processes is obtained. The mathematical model is generalized to DC-DC and AC-AC converters, to three basic types of converters and considers possibility of autotransformer inclusion of an inductor. It is shown that the use of bi-directional switches allows both DC and AC conversion of electrical energy regardless of the load type and also supports recuperation of electrical energy back to the source. It is shown that the maximum value of instant power in a load circuit in AC—AC converters exceeds twice the rated value of load power in comparison with DC—DC converters. It is shown that the energy capacity of an inductor in AC—AC converters exceeds twice the energy capacity of DC—DC converters at the identical rated power of conversion. It is shown that the energy capacity of an inductor in converters of buck and boost types depends on the ratio of input and output voltage. Also, the energy capacity of an inductor in converters of buck-boost type does not depend on the ratio of input and output voltage. It is shown that the energy capacity of an inductor in converters of buck and boost types is lower than the energy capacity of an inductor in the converter of buck-boost type.

  2. Autonomous Active Power Control for Islanded AC Microgrids with Photovoltaic Generation and Energy Storage System

    DEFF Research Database (Denmark)

    Wu, Dan; Tang, Fen; Dragicevic, Tomislav;

    2014-01-01

    , an autonomous active power control strategy is proposed for AC islanded microgrids in order to achieve power management in a decentralized manner. The proposed control algorithm is based on frequency bus-signaling of ESS and uses only local measurements for power distribution among microgrid elements. Moreover......, this paper also presents a hierarchical control structure for AC microgrids that is able to integrate the ESS, PV systems and loads. Hereby, basic power management function is realized locally in primary level, while strict frequency regulation can be achieved by using additional secondary controller......In an islanded AC microgrid with distributed energy storage system (ESS), photovoltaic (PV) generation and loads, a coordinated active power regulation is required to ensure efficient utilization of renewable energy, while keeping the ESS from overcharge and over discharge conditions. In this paper...

  3. The Single-Phase AC-DC Conversion Circuit with Power Factor Adjustable%功率因数可调单相AC-DC变换电路∗

    Institute of Scientific and Technical Information of China (English)

    杨力; 张师斌; 赵宁

    2015-01-01

    基于UCC28019A设计的功率因数可调单相AC-DC变换电路。 MSP430单片机作为其控制核心,使用高精度24 bitΣ-Δ型ADC采样,可完成对输入电压有效值、输入电流有效值、有功功率有效值、功率因数等参数的测量。由UCC28019A完成功率因数的校正,通过控制数字移相电路对外围电流反馈信号移相,实现功率因数在0.8~1.0范围内的调整。本设计还可通过对输出电流和电压的监测,实现2.5 A过流保护和36 V稳压输出的功能。%This design is a single-phase AC-DC conversion circuit with power factor adjustable based on UCC28019A. MSP430 is selected as the control core. We adopt the high precision 24-bitΣ-ΔADC to measure the input voltage RMS,the input current RMS,the active power RMS,the power factor and some other parameters. The power-factor correction is accomplished by UCC28019A. By controlling the digital phase shift circuit to shift the phase of the current feedback signal,the power factor can be set in the range of 0.8 to 1.0. By detecting the output current and voltage,the circuit has the function of 2.5A overcurrent protection and 36V regulated output.

  4. BOLD signal effects of transcranial alternating current stimulation (tACS) in the alpha range: A concurrent tACS-fMRI study.

    Science.gov (United States)

    Vosskuhl, Johannes; Huster, René J; Herrmann, Christoph S

    2016-10-15

    Many studies have proven transcranial alternating current stimulation (tACS) to manipulate brain activity. Until now it is not known, however, how these manipulations in brain activity are represented in brain metabolism or how spatially specific these changes are. Alpha-tACS has been shown to enhance the amplitude of the individual alpha frequency (IAF) and a negative correlation between alpha amplitude and occipital BOLD signal was reported in numerous EEG/fMRI experiments. Thus, alpha-tACS was chosen to test the effects of tACS on the BOLD signal. A reduction thereof was expected during alpha-tACS which shows the spatial extent of tACS effects beyond modeling studies. Three groups of subjects were measured in an MRI scanner, receiving tACS at either their IAF (N=11), 1Hz (control; N=12) or sham (i.e., no stimulation - a second control; N=11) while responding to a visual vigilance task. Stimulation was administered in an interleaved pattern of tACS-on runs and tACS-free baseline periods. The BOLD signal was analyzed in response to tACS-onset during resting state and in response to seldom target stimuli. Alpha-tACS at 1.0mA reduced the task-related BOLD response to visual targets in the occipital cortex as compared to tACS-free baseline periods. The deactivation was strongest in an area where the BOLD signal was shown to correlate negatively with alpha amplitude. A direct effect of tACS on resting state BOLD signal levels could not be shown. Our findings suggest that tACS-related changes in BOLD activity occur only as a modulation of an existing BOLD response.

  5. Chance-Constrained AC Optimal Power Flow for Distribution Systems With Renewables

    Energy Technology Data Exchange (ETDEWEB)

    DallAnese, Emiliano; Baker, Kyri; Summers, Tyler

    2017-09-01

    This paper focuses on distribution systems featuring renewable energy sources (RESs) and energy storage systems, and presents an AC optimal power flow (OPF) approach to optimize system-level performance objectives while coping with uncertainty in both RES generation and loads. The proposed method hinges on a chance-constrained AC OPF formulation where probabilistic constraints are utilized to enforce voltage regulation with prescribed probability. A computationally more affordable convex reformulation is developed by resorting to suitable linear approximations of the AC power-flow equations as well as convex approximations of the chance constraints. The approximate chance constraints provide conservative bounds that hold for arbitrary distributions of the forecasting errors. An adaptive strategy is then obtained by embedding the proposed AC OPF task into a model predictive control framework. Finally, a distributed solver is developed to strategically distribute the solution of the optimization problems across utility and customers.

  6. AC LED的研究现状与发展%Current research and development of AC LED

    Institute of Scientific and Technical Information of China (English)

    满瑞; 李秋俊

    2012-01-01

    介绍了AC LED的特征及其工作原理,分析了AC LED相比于DC LED的优缺点,概述了AC LED在国内外的研究进展及其应用现状,讨论了AC LED技术发展过程中面临的挑战,并展望了其发展趋势.%The characteristics and operation principles of AC LED were presented.The advantages and disadvantages of AC LED compared with the DC LED were analyzed.The development and the latest application of AC LED were described.The challenges of the competition with the traditional light source were discussed,as well as the development trend of AC LED.

  7. ac current generation in chiral magnetic insulators and Skyrmion motion induced by the spin Seebeck effect.

    Science.gov (United States)

    Lin, Shi-Zeng; Batista, Cristian D; Reichhardt, Charles; Saxena, Avadh

    2014-05-09

    We show that a temperature gradient induces an ac electric current in multiferroic insulators when the sample is embedded in a circuit. We also show that a thermal gradient can be used to move magnetic Skyrmions in insulating chiral magnets: the induced magnon flow from the hot to the cold region drives the Skyrmions in the opposite direction via a magnonic spin transfer torque. Both results are combined to compute the effect of Skyrmion motion on the ac current generation and demonstrate that Skyrmions in insulators are a promising route for spin caloritronics applications.

  8. Low-Power Magnetic Current Sensor

    Science.gov (United States)

    Mclyman, W. T.

    1989-01-01

    Direct current sensed via saturable-core reactor. Transducer senses direct current magnetically, providing isolation between input and output. Detecting-and-isolating element saturable reactor, where input current passes through one-turn control coil. Provides output of 0 to 3 Vdc for input current of 0 to 15 Adc and consumes power of 22 mW at 10 Adc input. Input sensed magnetically, output electrically isolated from input.

  9. A new low cost single phase ac-ac power line conditioner

    Directory of Open Access Journals (Sweden)

    Santosh Sonar 1, Tanmoy Maity

    2012-12-01

    Full Text Available The paper presents a comparative study of three topologies of recently developed voltage-fed z-source inverter (ZSI such as simple ZSI, quasi-ZSI and trans-ZSI. Different control techniques, proposed earlier for simple ZSI such as simple boost control, maximum boost control and constant boost control, have been applied here for all type of ZSI topologies. The detailed comparative evaluation of all topologies under different PWM techniques is done as power line conditioner. For the common boost factor and modulation index, the output voltage, line harmonics profile of all ZSIs powered by same source and load are evaluated. The operating principles are analysed and the boost factor, voltage gain, duty ratio and voltage stress across the switches are derived. Also the relationships among them are compared even under variable circuit parameters and switch frequency. The results would help to select suitable topology and PWM switching method for power line conditioner application.

  10. Study on AC loss measurements of HTS power cable for standardizing

    Science.gov (United States)

    Mukoyama, Shinichi; Amemiya, Naoyuki; Watanabe, Kazuo; Iijima, Yasuhiro; Mido, Nobuhiro; Masuda, Takao; Morimura, Toshiya; Oya, Masayoshi; Nakano, Tetsutaro; Yamamoto, Kiyoshi

    2017-09-01

    High-temperature superconducting power cables (HTS cables) have been developed for more than 20 years. In addition of the cable developments, the test methods of the HTS cables have been discussed and proposed in many laboratories and companies. Recently the test methods of the HTS cables is required to standardize and to common in the world. CIGRE made the working group (B1-31) for the discussion of the test methods of the HTS cables as a power cable, and published the recommendation of the test method. Additionally, IEC TC20 submitted the New Work Item Proposal (NP) based on the recommendation of CIGRE this year, IEC TC20 and IEC TC90 started the standardization work on Testing of HTS AC cables. However, the individual test method that used to measure a performance of HTS cables hasn’t been established as world’s common methods. The AC loss is one of the most important properties to disseminate low loss and economical efficient HTS cables in the world. We regard to establish the method of the AC loss measurements in rational and in high accuracy. Japan is at a leading position in the AC loss study, because Japanese researchers have studied on the AC loss technically and scientifically, and also developed the effective technologies for the AC loss reduction. The JP domestic commission of TC90 made a working team to discussion the methods of the AC loss measurements for aiming an international standard finally. This paper reports about the AC loss measurement of two type of the HTS conductors, such as a HTS conductor without a HTS shield and a HTS conductor with a HTS shield. The AC loss measurement method is suggested by the electrical method..

  11. Electrical Model of Balanced AC HTS Power Cable

    NARCIS (Netherlands)

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

    2012-01-01

    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 mor

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

    Science.gov (United States)

    Abdollahi, Rohollah

    2012-12-01

    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.

  13. Error Assessment of Solar Irradiance Forecasts and AC Power from Energy Conversion Model in Grid-Connected Photovoltaic Systems

    Directory of Open Access Journals (Sweden)

    Gianfranco Chicco

    2015-12-01

    Full Text Available Availability of effective estimation of the power profiles of photovoltaic systems is essential for studying how to increase the share of intermittent renewable sources in the electricity mix of many countries. For this purpose, weather forecasts, together with historical data of the meteorological quantities, provide fundamental information. The weak point of the forecasts depends on variable sky conditions, when the clouds successively cover and uncover the solar disc. This causes remarkable positive and negative variations in the irradiance pattern measured at the photovoltaic (PV site location. This paper starts from 1 to 3 days-ahead solar irradiance forecasts available during one year, with a few points for each day. These forecasts are interpolated to obtain more irradiance estimations per day. The estimated irradiance data are used to classify the sky conditions into clear, variable or cloudy. The results are compared with the outcomes of the same classification carried out with the irradiance measured in meteorological stations at two real PV sites. The occurrence of irradiance spikes in “broken cloud” conditions is identified and discussed. From the measured irradiance, the Alternating Current (AC power injected into the grid at two PV sites is estimated by using a PV energy conversion model. The AC power errors resulting from the PV model with respect to on-site AC power measurements are shown and discussed.

  14. The power supply system model of the process submersible device with AC power transmission over the cable-rope

    Science.gov (United States)

    Rulevskiy, V. M.; Bukreev, V. G.; Kuleshova, E. O.; Shandarova, E. B.; Shandarov, S. M.; Vasilyeva, Yu Z.

    2017-02-01

    A practical problem of power supply system modeling for the process submersible device with AC power transmission over the cable-rope was considered. The problem is highly relevant in developing and operation of submersible centrifugal pumps and submersibles. The results of modeling a symmetrical three-phase power supply system and their compliance with the real data are given at the paper. The obtained results in the mathematical and simulation models were similar.

  15. Practice and Prospect of AC/DC Hybrid Power Grid in Southern China

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    China Southern Power Grid is a unique EHV AC/DC hybrid transmission network that operates in China. In its service area, the distribution of energy resources and the development of economy are extremely unbalanced, so long-distance and bulk power transmission are needed; besides, the geography and climate conditions are serious, rains, fogs, lightning and typhoon as well as high temperature are common all the year round. Facing these challenges,the power grid enhanced stability control, improved the equipment and strengthen the network structure. In the future, the power grid plans to optimize the disposition of power sources and build digitalized power system.

  16. AC Power Consumption of Single-Walled Carbon Nanotube Interconnects: Non-Equilibrium Green's Function Simulation

    Science.gov (United States)

    Yamamoto, Takahiro; Sasaoka, Kenji; Watanabe, Satoshi

    2012-04-01

    We theoretically investigate the emittance and dynamic dissipation of a nanoscale interconnect consisting of a metallic single-walled carbon nanotube using the non-equilibrium Green's function technique for AC electronic transport. We show that the emittance and dynamic dissipation depend strongly on the contact conditions of the interconnect and that the power consumption can be reduced by adjusting the contact conditions. We propose an appropriate condition of contact that yields a high power factor and low apparent power.

  17. Current limiting remote power control module

    Science.gov (United States)

    Hopkins, Douglas C.

    1990-01-01

    The power source for the Space Station Freedom will be fully utilized nearly all of the time. As such, any loads on the system will need to operate within expected limits. Should any load draw an inordinate amount of power, the bus voltage for the system may sag and disrupt the operation of other loads. To protect the bus and loads some type of power interface between the bus and each load must be provided. This interface is most crucial when load faults occur. A possible system configuration is presented. The proposed interface is the Current Limiting Remote Power Controller (CL-RPC). Such an interface should provide the following power functions: limit overloading and resulting undervoltage; prevent catastrophic failure and still provide for redundancy management within the load; minimize cable heating; and provide accurate current measurement. A functional block diagram of the power processing stage of a CL-RPC is included. There are four functions that drive the circuit design: rate control of current; current sensing; the variable conductance switch (VCS) technology; and the algorithm used for current limiting. Each function is discussed separately.

  18. Methods, systems and apparatus for controlling operation of two alternating current (AC) machines

    Science.gov (United States)

    Gallegos-Lopez, Gabriel; Nagashima, James M.; Perisic, Milun; Hiti, Silva

    2012-02-14

    A system is provided for controlling two AC machines. The system comprises a DC input voltage source that provides a DC input voltage, a voltage boost command control module (VBCCM), a five-phase PWM inverter module coupled to the two AC machines, and a boost converter coupled to the inverter module and the DC input voltage source. The boost converter is designed to supply a new DC input voltage to the inverter module having a value that is greater than or equal to a value of the DC input voltage. The VBCCM generates a boost command signal (BCS) based on modulation indexes from the two AC machines. The BCS controls the boost converter such that the boost converter generates the new DC input voltage in response to the BCS. When the two AC machines require additional voltage that exceeds the DC input voltage required to meet a combined target mechanical power required by the two AC machines, the BCS controls the boost converter to drive the new DC input voltage generated by the boost converter to a value greater than the DC input voltage.

  19. Power control of a wind farm with active stall wind turbines and AC grid connection

    DEFF Research Database (Denmark)

    Hansen, Anca Daniela; Sørensen, Poul; Iov, Florin

    This paper describes the design of a centralised wind farm controller for a wind farm made-up exclusively of active stall wind turbines with AC grid connection. The overall aim of such controller is to enable the wind farms to provide the best grid support. The designed wind farm control involves...... both the control on wind turbine level as well as the central control on the wind farm level. The ability of active stall wind farms with AC grid connection to regulate the power production to the reference power ordered by the operators is assessed and discussed by means of simulations....

  20. Research and Development of Bi-2223-Based AC Power Cables in Russia

    Science.gov (United States)

    Vysotsky, Vitaly; Fetisov, Sergey; Sytnikov, Viktor

    The Russian program for R&D of AC power cables has been started in 2005. During the program, the several 5m prototypes and witness samples of Bi-2223 based cables have been tested, as along with the 30m experimental three phase cable. Eventually 200m full size AC power cable with ratings 20 kV 1.5/2kA and 50/70MVA has been developed and successfully tested. The review of cable designs and test results is presented.

  1. Thermal Impact Analysis of Circulating Current in High Power Modular Online Uninterruptible Power Supplies Application

    DEFF Research Database (Denmark)

    Zhang, Chi; Guerrero, Josep M.; Vasquez, Juan Carlos

    2015-01-01

    In a modular uninterruptible power supplies (UPS), each DC/AC module was designed to work in a circular way considering the reliability and power stress issues of the whole system. Thus unsynchronized PWMs will occur if any of the DC/AC modules is plugged in or out of the system at any time...

  2. AC transport current loss in a coated superconductor in the Bean model

    Energy Technology Data Exchange (ETDEWEB)

    Carr, W.J. [LEI, 700 Technology Drive, Pittsburgh, PA 15219 (United States)]. E-mail: wjamescarrjr@att.net

    2004-10-15

    A new and straightforward calculation is made of the loss in a very thin superconducting strip of rectangular cross-section (e.g. the coating on a coated superconductor) carrying ac transport current in zero applied magnetic field, with a similar strip acting as the return path. The computation is made assuming only that the strip is composed of uniform material which obeys Maxwell's equations and the Bean model. An important consequence of the Bean model is the existence of a field-free region about the middle of the superconductor cross-section. The present loss calculation is novel in two respects: (1) It uses for the first time an actual computation of the shape of the field-free region rather than using qualitative assumptions, and (2) it uses a new approach for making the loss calculation, based on a rigorous solution of Maxwell's equations for this problem. The rigorous solution correctly treats the problem as three-dimensional, having a time-dependent charge on the surface of the superconductor, and having the electric field described by both a vector and a scalar potential. Loss computations are made for the ratio of peak current to critical current in the approximate range of one-half to one, where within this range the loss decreases by about two powers of 10. The most important result coming out of the present calculation (made for the case of a distant return path large compared with the conductor cross-section dimensions but small compared with the length of the conductor), is a confirmation of Norris's previously estimated loss expression which he obtained in a different way.

  3. Six switches solution for single-phase AC/DC/AC converter with capability of second-order power mitigation in DC-link capacitor

    DEFF Research Database (Denmark)

    Liu, Xiong; Wang, Peng; Loh, Poh Chiang

    2011-01-01

    This paper proposes an approach for DC-link second-order harmonic power cancellation in single-phase AC/DC/AC converter with reduced number of switches. The proposed six-switch converter has two bridges with three switches in each of them, where the middle switch in each bridge is shared by the AC...... on their modulation indices of the six-switch converter, and high modulation indices are proved to be feasible for second-order power cancellation in the DC-link based on the phase difference analysis. Both reduced switch numbers and DC electrolytic capacitor size can be achieved using the proposed converter...

  4. A.c. Power Measurement Using Power Analyzer Associated with External Transducers. Accuracy and Uncertainty Evaluation

    Directory of Open Access Journals (Sweden)

    Marinel Popescu

    2014-09-01

    Full Text Available The development of the digital signal processors and their implementation in measuring technique has led to the manufacturing of power analyzers used as multifunction meters in industry, automation, tests and laboratory activities, monitoring and control of processes, etc. The parameters of a three-phase system can be known if the phase currents, the phase voltages and the phase difference between them can be known.A power analyzer has six inputs for currents and voltages measuring signals. The paper presents a method of determination of errors and uncertainties of electrical quantities measurement using a power analyzer associated with external transducers. The best estimation of measured quantity and uncertainty of measurement are used to report the result of measurement process.

  5. System Frequency as Information Carrier in AC Power Systems

    DEFF Research Database (Denmark)

    Douglass, Philip James; Heussen, Kai; You, Shi

    2015-01-01

    Power generators contain control systems able to regulate system frequency, but the frequency setpoint values are only rarely modified from nominal values. This paper describes design considerations for a communication system from generators to frequency sensitive distributed energy resourc es (FS...... to carry information: First, a protocol for dispatching blocks of FS- DER that is suitable for systems restricted to relatively slow rates of change of frequency (ROCOF). Second, for systems that allow higher ROCOF values, the feasibility of using power generation resources as a power line communication......-DER) using changes to frequency setpoint values of genera- tors. Signaling discrete system states by generating off-nominal system frequency values can be used as a novel narrowband unidirectional broadcast communications channel. This paper describes two protocols for utilizing off-nominal frequencies...

  6. Time-Resolved Magneto-Optical Imaging of Y1Ba2Cu3O7-delta Thin Films in High-Frequency AC Current Regime (Postprint)

    Science.gov (United States)

    2012-02-01

    ΘF=αB laser pulseAC time φ Figure 1. Schematic diagram of the time-resolved MO imaging setup. time-resolved imaging, we use a Q- switched Nd:YLF diode...controlled power source in order to obtain time-resolved MO images of the current flow in the sample. We use a 6 µm thick epitaxial grown ferrite ...the AC current. Ultimately the time resolution achievable with this method will be limited to sub-nanoseconds by the magnetization switching time of the

  7. The effects of bending strain on the critical current and AC loss of BSCCO/Ag tapes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guo Min [Center for Advanced Power Systems, Florida State University, Tallahassee, FL 32310 (United States); Schwartz, Justin [Center for Advanced Power Systems, Florida State University, Tallahassee, FL 32310 (United States); Sastry, P V P S S [Center for Advanced Power Systems, Florida State University, Tallahassee, FL 32310 (United States); Lin Liangzhen [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100080 (China); Xiao Liye [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100080 (China); Yu Yunjia [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100080 (China)

    2004-08-01

    When a coil or a winding is made, the superconducting tapes must be bent to different curvatures. Bending of high temperature superconducting (HTS) tapes can result in degradation of the critical current density and thus increase the AC losses of the tapes. Therefore, the effects of bending strain on the critical current and AC loss should be considered in the design of high temperature superconducting apparatus. In this paper, the dependence of critical current and AC loss on the bending diameter of the superconductor tape was experimentally investigated. The diameters of the curved tape were varied from 110 to 36 mm. AC loss measurements were taken at 77 K, 50 Hz. Analysis of the bending strain effects on the critical current and AC loss are presented. An expression describing the dependence of AC losses on bending strain is proposed by modifying Norris' formula. The experimental results are presented and compared with the calculated values.

  8. A High Power Factor Single-phase AC-DC Converter%一种高功率因数的单相AC-DC变换器

    Institute of Scientific and Technical Information of China (English)

    李雨; 丁志勇; 李鹏鹏

    2014-01-01

    设计了一种有源功率因数校正(APFC)的高功率因数单相AC-DC变换器。该系统以TI公司专用APFC控制芯片UCC28019为控制核心,实现BOOST式APFC,后级以高效控制芯片TPS54360为控制器,输出恒压36 V,最大输出电流为2.5 A。该系统采用STC12C5A60S2单片机为监测控制中心,具有输出过流保护和功率因数、输出电压、输出电流实时测量和显示功能。在设计时,该系统从布局布线和滤波等方面消除了电磁干扰,使电压调整率和负载调整率都在0.5%以下,工作性能稳定、可靠。%An active Power Factor Correction(APFC)high power factor single-phase AC-DC converter. The system is dedicated to TI’s UCC28019 APFC control chip to control the core, to achieve BOOST type APFC, after the class in an efficient control chip TPS54360 controller, constant voltage output 36 V, maximum output current of 2.5 A. The system uses STC12C5A60S2 microcontroller monitoring control center, with output overcurrent protection and power factor, output voltage, output current, real-time measurement and display functions. In the design, the system layout and filtering from the elimination of electromagnetic interference, voltage regulation and load regulation are 0.5%, stable performance, reliable.

  9. Coordinated Control Scheme for Ancillary Services from Offshore Wind Power Plants to AC and DC Grids

    DEFF Research Database (Denmark)

    Sakamuri, Jayachandra N.; Altin, Müfit; Hansen, Anca Daniela;

    2016-01-01

    This paper proposes a new approach of providing ancillary services to AC and DC grids from offshore wind power plants (OWPPs), connected through multi-terminal HVDC network. A coordinated control scheme where OWPP’s AC grid frequency modulated according to DC grid voltage variations is used...... to detect and provide the ancillary service requirements of both AC and DC grids, is proposed in this paper. In particular, control strategies for onshore frequency control, fault ridethrough support in the onshore grid, and DC grid voltage control are considered. The proposed control scheme involves only...... local measurements and therefore avoids the need of communication infrastructure otherwise required for communication based control, and thus increases the reliability of the control system. The effectiveness of the proposed control scheme is demonstrated on a MTDC connected wind power system developed...

  10. System and Battery Charge Control for PV-Powered AC Lighting Systems

    Energy Technology Data Exchange (ETDEWEB)

    Kern, G.

    1999-04-01

    This report reviews a number of issues specific to stand-alone AC lighting systems. A review of AC lighting technology is presented, which discusses the advantages and disadvantages of various lamps. The best lamps for small lighting systems are compact fluorescent. The best lamps for intermediate-size systems are high- or low-pressure sodium. Specifications for battery charging and load control are provided with the goal of achieving lamp lifetimes on the order of 16,000 to 24,000 hours and battery lifetimes of 4 to 5 years. A rough estimate of the potential domestic and global markets for stand-alone AC lighting systems is presented. DC current injection tests were performed on high-pressure sodium lamps and the test results are presented. Finally, a prototype system was designed and a prototype system controller (with battery charger and DC/AC inverter) was developed and built.

  11. Quadratic models of AC-DC power flow and optimal reactive power flow with HVDC and UPFC controls

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Juan; Yan, Wei; Wen, Lili [The Key Laboratory of High Voltage Engineering and Electrical New Technology, Ministry of Education, Electrical Engineering College of Chongqing University, Chongqing 400030 (China); Li, Wenyuan [British Columbia Transmission Corporation (BCTC), Suite 1100, Four Bentall Center, 1055 Dunsmuir Street, P.O. Box 49260, Vancouver, BC (Canada)

    2008-03-15

    Quadratic models of power flow (PF) and optimal reactive power flow (ORPF) for AC-DC power systems are proposed in the paper. Voltage magnitudes at the two sides of ideal converter transformers are used as additional state variables to build the quadratic models. Effects of converter controls on equality constraints are considered. The quadratic expression of unified power flow controller (UPFC) is also developed and incorporated into the proposed models. The proposed PF model retaining nonlinearity has a better convergence feature and requires less CPU time compared to traditional PF models. The Hessian matrices in the quadratic AC-DC ORPF model are constant and need to be calculated only once in the entire optimization process, which speeds up the calculation greatly. Results obtained from the four IEEE test systems and an actual utility system indicate that the proposed quadratic models achieve a superior performance than conventional models. (author)

  12. Research on Low Power Marine Current Power Generation System

    Directory of Open Access Journals (Sweden)

    Dongkai Peng

    2013-09-01

    Full Text Available This study proposes a simple topological structure and power control method for a small scale stand alone marine current system, in which a diode rectifier, DC/DC boost converter for the maximum power control, battery as a storage element and a single phase inverter to link with load. The study establishes the steady-state mathematical model of marine current power generation system and derives the formula between the maximum power point and dc battery voltage. Then use the measurements of DC voltage and DC current to obtain Maximum Power Point Tracking (MPPT by controlling the duty cycle of the boost converter switch in order to simplify the system structure and the control strategies. In this case, the hill climbing searching algorithm is employed to get maximum power point and the double closed loops control strategy is used to improve the dynamic and static performance of single phase inverter. The simulation model is developed in MATLAB/Simulink. And the control method is executed in dSPACE1104 real-time platform. The simulation and experimental results demonstrate the feasibility and validity of the proposed control strategies.

  13. Experimental investigation of the loss characteristics of superconductors for AC power applications

    NARCIS (Netherlands)

    Overbeeke, van Frank; Oordt, Klaas; Klundert, van de Louis J.M.

    1985-01-01

    Recent studies confirm the economical feasibility of the application of superconductors in AC power apparatus. The low-loss conductor which has been proposed still only exists in theory. Simple calculations show that the economic criterion described by Ogasawara and Hlásnik is inaccurate because of

  14. A Direct Power Conversion Topology for Grid Integration of Hybrid AC/DC Energy Resources

    DEFF Research Database (Denmark)

    Liu, Xiong; Loh, Poh Chiang; Wang, Peng;

    2013-01-01

    This paper proposes a multiple-input versatile matrix converter (VMC) for integrating hybrid ac/dc energy resources and storages to the power grid. The VMC is developed from the traditional indirect matrix converter but operates in the reverse-boost mode rather than in the forward-buck mode. The ...

  15. A direct power conversion topology for grid integrations of hybrid AC/DC resources

    DEFF Research Database (Denmark)

    Liu, Xiong; Loh, Poh Chiang; Wang, Peng;

    2012-01-01

    This paper proposes a multiple-input versatile matrix converter (VMC) to integrate hybrid ac/dc energy resources and storages to a power grid. The VMC is developed based on the indirect matrix converter (IMC) with its six-switch voltage source converter replaced by a nine-switch topology. The nine...

  16. Modelling and analysis of current-programmed ac/dc converters

    Science.gov (United States)

    Tymerski, R. P. E.; Daly, K. C.

    1985-03-01

    Current-programmed dc/dc converters operating at a fixed switching frequency are analyzed using state-space averaged modeling. For converters operating in the continuous conduction mode, general closed form expressions that describe the dynamic ac small signal characteristics of the converter are obtained. A reduced order model is used to derive the control current input-to-output voltage, audio susceptibility and output impedance small signal ac transfer functions for the ideal buck, boost, and buck-boost converters operating in the continuous conduction model. It is shown that state-space averaging can correctly predict instability on the buck converter. Current-programmed converters operating in the discontinuous conduction mode are addressed, showing that the transfer functions are represented by a finite pole and a zero at infinity. Instability is predicted for the buck converter when an external ramp is omitted and the output-to-input voltage ratio is greater than or equal to two-thirds.

  17. A New Generalized Two-Stage Direct Power Conversion Topology to Independently Supply Multiple AC Loads from Multiple Power Grids with Adjustable Power Loading

    DEFF Research Database (Denmark)

    Klumpner, Christian; Blaabjerg, Frede

    2004-01-01

    Normally, a power converter has one supply port to connect to the power grid and one output port to connect to an AC load that requires variable voltage and variable frequency. Converter topologies with multiple output ports, the so-called multi-drive converters are also used in order to share......) and continuously adjust these power fractions will become a desired feature. This paper presents a generalized Direct Power Converter topology, which is able to connect to multiple AC supplies proving complete decoupling and no circulating power between the input ports and to independently control multiple AC...... the cost of an active front-end rectifier. As the trend on the energy market is towards deregulation, new converter topologies are needed to allow independent producers/consumers to connect to multiple distribution grids in order to minimize the electricity price. Having the possibility to adjust smoothly...

  18. Power Loss Analysis and Comparision of DC and AC Side Decoupling Module in a H-bridge Inverter

    DEFF Research Database (Denmark)

    Ma, Siyuan; Wang, Haoran; Zhu, Guorong;

    2016-01-01

    In single-phase inverters, a considerable amount of low-frequency ripples appear on the DC side due to the instantaneous power imbalance between the DC side and AC side. Recently, active methods using film capacitors or inductors as ripple power storage components introduced at the DC or AC side...

  19. AC/DC and DC/AC Converty Circuits in Power Supply Equipment%电源设备中AC/DC和DC/AC变换电路

    Institute of Scientific and Technical Information of China (English)

    杨碧石

    2001-01-01

    电源设备中根据电路变换功能来看,可分为四种类型:AC/DC、DC/AC、DC/DC、AC/AC,本文对AC/DC、DC/AC这两种变换的工作原理进行分析阐述并讨论每种电路的应用领域.

  20. Effect of arc current on droplet ejection from tungsten-based electrode in multiphase AC arc

    Science.gov (United States)

    Hashizume, Taro; Tanaka, Manabu; Watanabe, Takayuki

    2017-05-01

    The dynamic behavior of droplet ejection from a tungsten electrode was successfully visualized using a high-speed camera and an appropriate band-pass filter. The effect of arc current on droplet ejection was investigated to understand the electrode erosion mechanism in the multiphase AC arc. The rate of erosion by droplet ejection increased with increasing current. This result was examined on the basis of the time variation in forces on a pending droplet at the electrode tip during the AC cycle. The relationship among electromagnetic force, surface tension, and ion pressure on the molten tip during the cathodic period is crucial for controling droplet ejection. The molten tip becomes hemispherical forming the pending droplet with an increase in the instantaneous value of arc current during the AC cycle. The pending droplet detaches from the electrode surface when electromagnetic force becomes the dominant force. Consequently, a higher rate of erosion by droplet ejection with a higher arc current resulted from a stronger electromagnetic force.

  1. Adapting AC Lines to DC Grids for Large-Scale Renewable Power Transmission

    Directory of Open Access Journals (Sweden)

    D. Marene Larruskain

    2014-10-01

    Full Text Available All over the world, governments of different countries are nowadays promoting the use of clean energies in order to achieve sustainable energy systems. In this scenario, since the installed capacity is continuously increasing, renewable sources can play an important role. Notwithstanding that, some important problems may appear when connecting these sources to the grid, being the overload of distribution lines one of the most relevant. In fact, renewable generation is usually connected to the nearest AC grid, although this HV system may not have been designed considering distributed generation. In the particular case of large wind farms, the electrical grid has to transmit all the power generated by wind energy and, as a consequence, the AC system may get overloaded. It is therefore necessary to determine the impact of wind power transmission so that appropriate measures can be taken. Not only are these measures influenced by the amount of power transmitted, but also by the quality of the transmitted power, due to the output voltage fluctuation caused by the highly variable nature of wind. When designing a power grid, although AC systems are usually the most economical solution because of its highly proven technology, HVDC may arise in some cases (e.g. offshore wind farms as an interesting alternative, offering some added values such as lower losses and better controllability. This way, HVDC technology can solve most of the aforementioned problems and has a good potential for future use. Additionally, the fast development of power electronics based on new and powerful semiconductor devices allow the spread of innovative technologies, such as VSC-HVDC, which can be applied to create DC grids. This paper focuses on the main aspects involved in adapting the existing overhead AC lines to DC grids, with the objective of improving the transmission of distributed renewable energy to the centers of consumption.

  2. A New Coordinated Voltage Control Scheme for Offshore AC Grid of HVDC Connected Offshore Wind Power Plants

    DEFF Research Database (Denmark)

    Sakamuri, Jayachandra N.; Cutululis, Nicolaos Antonio; Rather, Zakir Hussain;

    2015-01-01

    This paper proposes a coordinated voltage control scheme (CVCS) which enhances the voltage ride through (VRT) capability of an offshore AC grid comprised of a cluster of offshore wind power plants (WPP) connected through AC cables to the offshore voltage source converter based high voltage DC (VSC-HVDC......) converter station. Due to limited short circuit power contribution from power electronic interfaced variable speed wind generators and with the onshore main grid decoupled by the HVDC link, the offshore AC grid becomes more vulnerable to dynamic voltage events. Therefore, a short circuit fault...... in the offshore AC Grid is likely to have significant implications on the voltage of the offshore AC grid, hence on the power flow to the onshore mainland grid. The proposed CVCS integrates individual local reactive power control of wind turbines and of the HVDC converter with the secondary voltage controller...

  3. Instantaneous characteristics simulation and analysis on three-level brushless AC synchronous generators of aeronautic constant speed and frequency AC power system

    Science.gov (United States)

    Ma, Xiaohe; Shen, Songhua

    2006-11-01

    This paper mainly introduces theoretical analysis and experimental results of instantaneous characteristics on a certain three level brushless three-phase AC synchronous generators. The analysis, modeling and simulations with Simplorer software of Ansoft Company are carried out. It establishes three level generator models, gives theoretical relation matrix equation, and simulates some instantaneous characteristics. Design of the system requires reliable simulation tools with comprehensive component libraries capable of dealing with complex system behavior. The simulation results verify that the proposed system model can efficiently simulate the instantaneous characteristics of the real AC generator system. It gives better design experiences and digital methods for aeronautic constant speed and frequency AC power system.

  4. Current distribution effects in AC impedance spectroscopy of electroceramic point contact and thin film model electrodes

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Jacobsen, Torben

    2010-01-01

    The Finite-Element-Method (FEM) was used for the simulations of the effect of a changing current distribution during AC impedance spectrum recording on electroceramic point contact and thin film model electrodes. For pure electronic conducting point contact electrodes the transition from the prim......The Finite-Element-Method (FEM) was used for the simulations of the effect of a changing current distribution during AC impedance spectrum recording on electroceramic point contact and thin film model electrodes. For pure electronic conducting point contact electrodes the transition from...... regarding its significance is provided. The associated characteristic impedance spectrum shape change is simulated and its origin discussed. Furthermore, the characteristic shape of impedance spectra of thin electroceramic film electrodes with lateral ohmic resistance is studied as a function...

  5. An Annotated Bibliography of High-Voltage Direct-Current Transmission and Flexible AC Transmission (FACTS) Devices, 1991-1993.

    Energy Technology Data Exchange (ETDEWEB)

    Litzenberger, Wayne; Lava, Val

    1994-08-01

    References are contained for HVDC systems, converter stations and components, overhead transmission lines, cable transmission, system design and operations, simulation of high voltage direct current systems, high-voltage direct current installations, and flexible AC transmission system (FACTS).

  6. Mapping entrained brain oscillations during transcranial alternating current stimulation (tACS).

    Science.gov (United States)

    Witkowski, Matthias; Garcia-Cossio, Eliana; Chander, Bankim S; Braun, Christoph; Birbaumer, Niels; Robinson, Stephen E; Soekadar, Surjo R

    2016-10-15

    Transcranial alternating current stimulation (tACS), a non-invasive and well-tolerated form of electric brain stimulation, can influence perception, memory, as well as motor and cognitive function. While the exact underlying neurophysiological mechanisms are unknown, the effects of tACS are mainly attributed to frequency-specific entrainment of endogenous brain oscillations in brain areas close to the stimulation electrodes, and modulation of spike timing dependent plasticity reflected in gamma band oscillatory responses. tACS-related electromagnetic stimulator artifacts, however, impede investigation of these neurophysiological mechanisms. Here we introduce a novel approach combining amplitude-modulated tACS during whole-head magnetoencephalography (MEG) allowing for artifact-free source reconstruction and precise mapping of entrained brain oscillations underneath the stimulator electrodes. Using this approach, we show that reliable reconstruction of neuromagnetic low- and high-frequency oscillations including high gamma band activity in stimulated cortical areas is feasible opening a new window to unveil the mechanisms underlying the effects of stimulation protocols that entrain brain oscillatory activity.

  7. Power Balance Control in an AC/DC/AC Converter for Regenerative Braking in a Two-Voltage-Level Flywheel-Based Driveline

    Directory of Open Access Journals (Sweden)

    Janaína G. Oliveira

    2011-01-01

    Full Text Available The integration of a flywheel as a power handling can increase the energy storage capacity and reduce the number of battery charge/discharge cycles. Furthermore, the ability of recovering energy of the vehicle during breaking can increase the system efficiency. The flywheel-based all-electric driveline investigated here has its novelty in the use of a double-wound flywheel motor/generator, which divides the system in two different voltage levels, enhancing the efficiency of the electric driveline. The connection of two AC electrical machines (i.e., the flywheel and the wheel motor with different and variable operation frequency is challenging. A power matching control applied to an AC/DC/AC converter has been implemented. The AC/DC/AC converter regenerates the electric power converted during braking to the flywheel machine, used here as power handling device. By controlling the power balance, the same hardware can be used for acceleration and braking, providing the reduction of harmonics and robust response. A simulation of the complete system during braking mode has been performed both in Matlab and Simulink, and their results have been compared. The functionality of the proposed control has been shown and discussed, with full regeneration achieved. A round-trip efficiency (wheel to wheel higher than 80% has been obtained.

  8. Electromechanical systems with transient high power response operating from a resonant ac link

    Science.gov (United States)

    Burrows, Linda M.; Hansen, Irving G.

    1992-01-01

    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 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 under contract to NASA.

  9. Tidal power harnessing energy from water currents

    CERN Document Server

    Lyatkher, Victor

    2014-01-01

    As the global supply of conventional energy sources, such as fossil fuels, dwindles and becomes more and more expensive, unconventional and renewable sources of energy, such as power generation from water sources, is becoming more and more important.  Hydropower has been around for decades, but this book suggests new methods that are more cost-effective and less intrusive to the environment for creating power sources from rivers, the tides, and other sources of water.   The energy available from water currents is potentially much greater than society's needs.  Presenting a detailed discussi

  10. Design of a High Power Factor Single-phase AC-DC Regulated Power Supply%一种高功率因数单相AC-DC稳压电源的设计

    Institute of Scientific and Technical Information of China (English)

    谭洁; 李恒; 沐润志

    2015-01-01

    针对目前AC-DC稳压电源转换率、稳压效果不理想,提出了一种高功率因数单相AC-DC稳压电源设计方案。以UCC28019芯片为校正核心实现有源功率因数校正,通过对BOOST主电路拓扑结构的升压电路的输入电流进行控制,使其达到与输入电压相位差为0,功率因数接近于1。本设计以单片机为控制核心,通过按键设置输出电压给定值,实时比较输出电压实测值与给定值,自动调节PWM波形占空比,进而控制MOS管的关断频率使输出电压稳定。%Aiming at the present AC-DC, the regulated power supply conversion rate and the regulated effect of it are not satisfied. This paper puts forward a kind of design scheme with high power factor single-phase AC-DC regulated power supply. The UCC28019 correction chip is the core of this design to realize the active power factor correction. In order to make the input current and the input voltage phase difference reach 0 and the power factor is close to 1, this paper uses the topology of BOOST circuit as main circuit to control the input current. At the same time, this design takes SCM as the core of the control to set up the output voltage by the button. Then, through comparing the actual output voltage and the output voltage, the waveform of PWM will be automatically adjusted and the cut-off frequency of MOS tube is controlled to ensure the stabilization of the output voltage.

  11. Development of a method to evaluate shared alternate AC power source effects in multi-unit nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Woo Sik; Yang, Joon Eun

    2003-07-01

    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 (LOOP) conditions. The approach is illustrated for two cases, 2 units and 4 units at a single site, and generalized for a multi-unit site. Furthermore, the SBO frequency of the first unit of the 2-unit site is quantified. The SBO frequency at a target unit of Probabilistic Safety Assessment (PSA) could be underestimated if the inter-unit dependency of the shared AAC power source is not properly modeled. The effect of the inter-unit behavior of the shared AAC power source on the SBO frequency is not negligible depending on the Common Cause Failure (CCF) characteristics among AC power sources. The methodology suggested in the present report is believed to be very useful in evaluating the SBO frequency and the core damage frequency resulting from the SBO event. This approach is also applicable to the probabilistic evaluation of the other shared systems in a multi-unit nuclear power plant.

  12. DC Link Current Estimation in Wind-Double Feed Induction Generator Power Conditioning System

    Directory of Open Access Journals (Sweden)

    MARIAN GAICEANU

    2010-12-01

    Full Text Available In this paper the implementation of the DC link current estimator in power conditioning system of the variable speed wind turbine is shown. The wind turbine is connected to double feed induction generator (DFIG. The variable electrical energy parameters delivered by DFIG are fitted with the electrical grid parameters through back-to-back power converter. The bidirectional AC-AC power converter covers a wide speed range from subsynchronous to supersynchronous speeds. The modern control of back-to-back power converter involves power balance concept, therefore its load power should be known in any instant. By using the power balance control, the DC link voltage variation at the load changes can be reduced. In this paper the load power is estimated from the dc link, indirectly, through a second order DC link current estimator. The load current estimator is based on the DC link voltage and on the dc link input current of the rotor side converter. This method presents certain advantages instead of using measured method, which requires a low pass filter: no time delay, the feedforward current component has no ripple, no additional hardware, and more fast control response. Through the numerical simulation the performances of the proposed DC link output current estimator scheme are demonstrated.

  13. Single stage single phase active power factor corrected Ĉuk Topology Based AC-DC Converter

    Directory of Open Access Journals (Sweden)

    Md. Ismail Hossain

    2014-03-01

    Full Text Available This paper focuses on the analysis of a power factor correction (PFC converter using close loop Ĉuk topology. Regardless of the input line voltage and output load variations, input current drawn by the buck or buck-boost converter is always discontinuous. The Boost converter suffers from high voltage stresses across the power electronic devices. The input current in Ĉuk converter is comparable to boost converter’s input current. In this paper output voltage is controlled by inner current and outer voltage control loop along with power factor correction (PFC. It shows less input current THD, nearly unity power factor and better output voltage regulation of AC-DC converter under variable input voltage and output load. In this paper the relative performance between normal diode rectifier, open loop Ĉuk rectifier and close loop Ĉuk rectifier is presented. An algorithm for implementing close loop Ĉuk rectifier in digital domain is developed and simulated.

  14. Current fusion power plant design concepts

    Energy Technology Data Exchange (ETDEWEB)

    Gore, B.F.; Murphy, E.S.

    1976-09-01

    Nine current U.S. designs for fusion power plants are described in this document. Summary tabulations include a tenth concept, for which the design document was unavailable during preparation of the descriptions. The information contained in the descriptions was used to define an envelope of fusion power plant characteristics which formed the basis for definition of reference first commercial fusion power plant design. A brief prose summary of primary plant features introduces each of the descriptions contained in the body of this document. In addition, summary tables are presented. These tables summarize in side-by-side fashion, plant parameters, processes, combinations of materials used, requirements for construction materials, requirements for replacement materials during operation, and production of wastes.

  15. Design of 6 W isolated flyback AC/DC power supply%6W隔离反激式AC/DC电源设计

    Institute of Scientific and Technical Information of China (English)

    冯欣宇; 黄阿娟

    2015-01-01

    介绍了基于UCC28910的5 V/1.2 A隔离反激式开关电源.电路结构简单,所需外部元件较少,有效减少了电路板占用面积.电源可实现AC 85~265 V宽电压输入,在无需光耦合器的情况下实现恒定电压与恒定电流输出.具有700 V高压启动和小于30 mW待机功耗的特点.采用DCM模式减少开关损耗,符合Energy StarEPS 2.0标准.%The design of 5 V/1.2 A isolated flyback switching power supply based on UCC28910 is introduced. Its circuit structure is simple and fewer external components are required,which reduces the area occupied by PCB effectively. The power supply can accepts a wide range voltage input of 85 VAC to 265 VAC. The constant voltage and current output was realized without any opto-coupler. This device has characteristics of 700 V high-voltage start and less than 30 mW standby power loss. DCM mode is used to reduce the switching loss,which is consistent with the standard of Energy Star EPS2.0.

  16. Improved SCR ac Motor Controller for Battery Powered Urban Electric Vehicles

    Science.gov (United States)

    Latos, T. S.

    1982-01-01

    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.

  17. Three-Phase AC Optimal Power Flow Based Distribution Locational Marginal Price: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rui; Zhang, Yingchen

    2017-05-17

    Designing market mechanisms for electricity distribution systems has been a hot topic due to the increased presence of smart loads and distributed energy resources (DERs) in distribution systems. The distribution locational marginal pricing (DLMP) methodology is one of the real-time pricing methods to enable such market mechanisms and provide economic incentives to active market participants. Determining the DLMP is challenging due to high power losses, the voltage volatility, and the phase imbalance in distribution systems. Existing DC Optimal Power Flow (OPF) approaches are unable to model power losses and the reactive power, while single-phase AC OPF methods cannot capture the phase imbalance. To address these challenges, in this paper, a three-phase AC OPF based approach is developed to define and calculate DLMP accurately. The DLMP is modeled as the marginal cost to serve an incremental unit of demand at a specific phase at a certain bus, and is calculated using the Lagrange multipliers in the three-phase AC OPF formulation. Extensive case studies have been conducted to understand the impact of system losses and the phase imbalance on DLMPs as well as the potential benefits of flexible resources.

  18. Analysis of the ac SQUID with low inductance and low critical current

    DEFF Research Database (Denmark)

    Sørensen, O. H.

    1976-01-01

    The properties of the ac SQUID magnetometer has been analyzed. The results are valid in the low-inductance low-critical-current regime, where the Lri0 producted is belowthe value at which the relation between the enclosed and externally applied magnetic dc flux becomes reentrant. The effects...... of the screening current circulating in the SQUID ring as well as of the SQUID-ring time constant, tau-Lr/R9 are taken into account. Here LR IS THE SQUID-ring inductance, and R is the shunt resistance in the shunted junction model assumed to describe the weak link. It is shown that for finite values of omegatau...

  19. Artificial Cooperative Search Algorithm based Load Frequency Control of Interconnected Power Systems with AC-DC Tie-lines

    Directory of Open Access Journals (Sweden)

    S. Ramesh kumar

    2014-05-01

    Full Text Available A maiden effort for optimal tuning of load frequency controller parameters using Artificial Cooperative Search (ACS algorithm for a two area interconnected power system with AC-DC parallel tie-lines has been presented in this paper. ACS is a recent swarm intelligence algorithm developed for solving numerical optimization problems. The swarm intelligence philosophy behind ACS algorithm is based on the migration of two artificial superorganisms as they biologically interact to achieve the global minimum value pertaining to the problem. The HVDC link in parallel with AC tie-line is used as system interconnection to effectively damp the frequency oscillations of the AC system. An integral square error criterion (ISE has been used as performance index to design the optimal parameters. A comparative study of tuned values has been presented to show the effectiveness of the Artificial Cooperative Search algorithm. The results demonstrate the success of ACS algorithm in solving Load frequency control (LFC optimization problem.

  20. Effect of DC Link Control Strategies on Multiterminal AC-DC Power Flow

    Directory of Open Access Journals (Sweden)

    Shagufta Khan

    2015-01-01

    Full Text Available For power-flow solution of power systems incorporating multiterminal DC (MTDC network(s, five quantities are required to be solved per converter. On the other hand, only three independent equations comprising two basic converter equations and one DC network equation exist per converter. Thus, for solution, two additional equations are required. These two equations are derived from the control specifications adopted for the DC links. Depending on the application, several combinations of valid control specifications are possible. Each combination of a set of valid control specifications is known as a control strategy. The number of control strategies increases with an increase in the number of the DC terminals or converters. It is observed that the power-flow convergence of integrated AC-MTDC power systems is strongly affected by the control strategy adopted for the DC links. This work investigates the mechanism by which different control strategies affect the power-flow convergence pattern of AC-MTDC power systems. To solve the DC variables in the Newton-Raphson (NR power-flow model, sequential method is considered in this paper. Numerous case studies carried out on a three-terminal DC network incorporated in the IEEE-300 bus test system validate this.

  1. A linearly controlled direct-current power source for high-current inductive loads in a magnetic suspension wind tunnel

    Science.gov (United States)

    Tripp, John S.; Daniels, Taumi S.

    1990-01-01

    The NASA Langley 6 inch magnetic suspension and balance system (MSBS) requires an independently controlled bidirectional DC power source for each of six positioning electromagnets. These electromagnets provide five-degree-of-freedom control over a suspended aerodynamic test model. Existing power equipment, which employs resistance coupled thyratron controlled rectifiers as well as AC to DC motor generator converters, is obsolete, inefficient, and unreliable. A replacement six phase bidirectional controlled bridge rectifier is proposed, which employs power MOSFET switches sequenced by hybrid analog/digital circuits. Full load efficiency is 80 percent compared to 25 percent for the resistance coupled thyratron system. Current feedback provides high control linearity, adjustable current limiting, and current overload protection. A quenching circuit suppresses inductive voltage impulses. It is shown that 20 kHz interference from positioning magnet power into MSBS electromagnetic model position sensors results predominantly from capacitively coupled electric fields. Hence, proper shielding and grounding techniques are necessary. Inductively coupled magnetic interference is negligible.

  2. A linearly controlled direct-current power source for high-current inductive loads in a magnetic suspension wind tunnel

    Science.gov (United States)

    Tripp, John S.; Daniels, Taumi S.

    1990-08-01

    The NASA Langley 6 inch magnetic suspension and balance system (MSBS) requires an independently controlled bidirectional DC power source for each of six positioning electromagnets. These electromagnets provide five-degree-of-freedom control over a suspended aerodynamic test model. Existing power equipment, which employs resistance coupled thyratron controlled rectifiers as well as AC to DC motor generator converters, is obsolete, inefficient, and unreliable. A replacement six phase bidirectional controlled bridge rectifier is proposed, which employs power MOSFET switches sequenced by hybrid analog/digital circuits. Full load efficiency is 80 percent compared to 25 percent for the resistance coupled thyratron system. Current feedback provides high control linearity, adjustable current limiting, and current overload protection. A quenching circuit suppresses inductive voltage impulses. It is shown that 20 kHz interference from positioning magnet power into MSBS electromagnetic model position sensors results predominantly from capacitively coupled electric fields. Hence, proper shielding and grounding techniques are necessary. Inductively coupled magnetic interference is negligible.

  3. Approach for Wide Use of Diagnostic Method for XLPE Cables Using Harmonics in AC Loss Current

    Science.gov (United States)

    Tsujimoto, Tomiyuki; Nakade, Masahiko; Yagi, Yukihiro; Ishii, Noboru

    Water tree is one of the degradation aspects of XLPE cables used for under-ground distribution or transmission lines. We have developed the loss current method using 3rd harmonic in AC loss current for cable diagnosis. Harmonic components in loss current arise as a result of the non-linear voltage-current characteristics of water trees. We confirmed that the 3rd harmonic in AC loss current had good correlation with water tree growth and break down strength. After that, we have applied this method to the actual 66kV XLPE cable lines. Up to now, the number of the application results is more than 130 lines. In case of cable lines terminated at gas-insulated switchgear (GIS), we have to remove the lightning arrestor (LA) and the potential transformer (PT) out of the test circuit. The reason is that we are afraid that each of LA and PT disturbs the degradation signal from cable lines. It takes extra time (1 or 2 days) and costs more to remove LA and PT in GIS out of a circuit. In order to achieve easy and reasonable diagnosis, we have developed a new method for cable lines terminated at GIS, by utilizing a technique, which enables to reduce signal of LA and PT from disturbed signal of cable lines. We confirmed the effect of the new method by experiments with actual cables.

  4. Harmonic Analysis of AC-DC Topologies and their Impacts on Power Systems

    Directory of Open Access Journals (Sweden)

    Mukhtiar Ahmed Mahar

    2011-01-01

    Full Text Available Power Electronic Converters are commonly used in different applications because of high efficiency and low cost. Due to latest advancement in semiconductor devices it is difficult to draw the boundaries for applications of power electronic topologies. These topologies are variable structure systems and generate harmonics during the operation which will affect the power quality when are connected to system network. Rectifier is a big family of converters and used when ac-dc conversion is needed. These converters are widely used in distribution system. Therefore, it is necessary to predict the harmonic levels of these converters and also observe their impacts on system network. Pakistan now days facing serious energy crises specially, in power sector due to increase in load demand. To bridge the gap between load demand and generation of electricity, various steps are taken by power companies and government. The steps include the up gradation of existing power plants, generation of power from rental power plants, installation of renewable power sources, taking different steps of demand side management etc. But efforts of power companies on power quality is still lacking. This research work focuses on power quality of the system network. In this work, harmonics of single phase and three phase full bridge diode rectifiers are analyzed by using the fast fourier transform method of MATLAB. The effects of harmonics on the system network are also discussed.

  5. Adaptive Current Control with PI-Fuzzy Compound Controller for Shunt Active Power Filter

    Directory of Open Access Journals (Sweden)

    Juntao Fei

    2013-01-01

    Full Text Available An adaptive control technology and PI-fuzzy compound control technology are proposed to control an active power filter (APF. AC side current compensation and DC capacitor voltage tracking control strategy are discussed and analyzed. Model reference adaptive controller for the AC side current compensation is derived and established based on Lyapunov stability theory; proportional and integral (PI fuzzy compound controller is designed for the DC side capacitor voltage control. The adaptive current controller based on PI-fuzzy compound system is compared with the conventional PI controller for active power filter. Simulation results demonstrate the feasibility and satisfactory performance of the proposed control strategies. It is shown that the proposed control method has an excellent dynamic performance such as small current tracking error, reduced total harmonic distortion (THD, and strong robustness in the presence of parameters variation and nonlinear load.

  6. AC/DC Power Flow Computation Based on Improved Levenberg-Marquardt Method

    Science.gov (United States)

    Cao, Jia; Yan, Zheng; Fan, Xiang; Xu, Xiaoyuan; Li, Jianhua; Cao, Lu

    2015-02-01

    Under the case of ill-conditioning system, this paper is concerned with the AC/DC power flow calculation. The improved Levenberg-Marquardt (ILM) method with adaptive damping factor selection is applied to solve the AC/DC power flow problem. The main purpose of this paper is as follows: one is to provide comparison reference between Newton method, classical LM method (CLM) and ILM method under the well-conditioning system; the other is to research what is the maximal load withstood by power system, under the case of ill-conditioning. Finally, those methods are tested on the 22-bus, the IEEE 118-bus AC/DC system, respectively. Numerical results indicate that the ILM method has the advantage of fast convergent speed. When expanding loads in a certain extent, ILM method can at least find least square solutions, whereas Newton method and CLM method would divergent, and the convergent property of Newton method can be improved by taking some measurements using the information of a least square solution obtained by ILM method.

  7. New Design of a Low Cost Analogue Current Supply for Power LEDs

    Directory of Open Access Journals (Sweden)

    Radu Bogdan Dragomir

    2013-04-01

    Full Text Available The present paper proposes an innovative and inductive ballast-based power LED supply. This new design LED powering solution is a cost-efficient alternative to high-end switching mode power supply (SMPS used to feed LED clusters. The current supply circuit topology will be explained. The AC component of the LED current is analysed both from the ballast inductance and the value of the DC filtering capacitor standpoint. The PSIM and MATLAB tools have been used to simulate the circuit output when different ballast voltage conditions will be applied. Transitory and steady-state driver performances have been taken into account.

  8. Experimental Study on the Influence of AC Stray Current on the Cathodic Protection of Buried Pipe

    Directory of Open Access Journals (Sweden)

    Qingmiao Ding

    2016-01-01

    Full Text Available The size of the damaged area of the coating and its position on the pipeline impacted the cathodic protection potential, and there was a damaged area of the greatest impact value. When damaged area was 300 mm2, the IR drop was the largest, and this situation could easily lead to inadequate protection; when the parallel spacing between pipeline and interference source was unchanged, the measured value curves of cathodic protection potential presented “U” shaped trend with the increasing stray current interference intensity. Under certain parallel spacing between pipeline and interference source, high alternating stray current intensity would cause serious negative offsets, so that the overprotection of the pipeline occurred, and make the coating crack; there was a parallel threshold length. When less than the threshold, the pipe-ground potential increases rapidly with the parallel length increasing. In order to judge whether a pipeline was interference by AC stray current and the risk of stray current corrosion, we should make a comprehensive analysis of the cathodic protection energizing potential, the switch-off potential, AC pipe-soil potential, IR drops, and so on.

  9. Coordinated Stability Control of Wind-Thermal Hybrid AC/DC Power System

    Directory of Open Access Journals (Sweden)

    Zhiqing Yao

    2015-01-01

    Full Text Available The wind-thermal hybrid power transmission will someday be the main form of transmitting wind power in China but such transmission mode is poor in system stability. In this paper, a coordinated stability control strategy is proposed to improve the system stability. Firstly, the mathematical model of doubly fed wind farms and DC power transmission system is established. The rapid power controllability of large-scale wind farms is discussed based on DFIG model and wide-field optical fiber delay feature. Secondly, low frequency oscillation and power-angle stability are analyzed and discussed under the hybrid transmission mode of a conventional power plant with wind farms. A coordinated control strategy for the wind-thermal hybrid AC/DC power system is proposed and an experimental prototype is made. Finally, real time simulation modeling is set up through Real Time Digital Simulator (RTDS, including wind power system and synchronous generator system and DC power transmission system. The experimental prototype is connected with RTDS for joint debugging. Joint debugging result shows that, under the coordinated control strategy, the experimental prototype is conductive to enhance the grid damping and effectively prevents the grid from occurring low frequency oscillation. It can also increase the transient power-angle stability of a power system.

  10. AC/DC Power Conversion System Using 3/9 Multiphase Transformer

    Directory of Open Access Journals (Sweden)

    Ahmad Hoteit

    2012-07-01

    Full Text Available The main idea of this paper is to build a 3/9 AC multiphase transformer for conversion into DC power through the rectifier circuit which contains 18 pulse rectification with a ripple factor less than 0.8% produced by the odd phase number 9. This modeling has been simulated using Orcad simulation software, the nine phases are out of the main three phase power lines, each phase is shifted from the other by 40o (360o/9, this type of transformer is often required in aerospace, railway and automobile applications.

  11. ac electrokinetic micropumps: The effect of geometrical confinement, Faradaic current injection, and nonlinear surface capacitance

    DEFF Research Database (Denmark)

    Olesen, Laurits Højgaard; Bruus, Henrik; Ajdari, A.

    2006-01-01

    Recent experiments have demonstrated that ac electrokinetic micropumps permit integrable, local, and fast pumping (velocities similar to mm/s) with low driving voltage of a few volts only. However, they also displayed many quantitative and qualitative discrepancies with existing theories. We...... therefore extend the latter theories to account for three experimentally relevant effects: (i) vertical confinement of the pumping channel, (ii) Faradaic currents from electrochemical reactions at the electrodes, and (iii) nonlinear surface capacitance of the Debye layer. We report here that these effects...... indeed affect the pump performance in a way that we can rationalize by physical arguments....

  12. Active Power and DC-link Voltage Coordinative Control for Cascaded DC-AC Converter with Bidirectional Power Application

    DEFF Research Database (Denmark)

    Tian, Yanjun; Chen, Zhe; Deng, Fujin;

    2015-01-01

    Two stage cascaded converters are widely used in DC/AC hybrid systems to achieve the bidirectional power transmission. The topology of dual active bridge cascaded with inverter (DABCI) is commonly used in this application. This paper proposes a coordinative control method for DABCI and it’s able...... to reduce the DC-link voltage fluctuation between the DAB and inverter, then reduce the stress on the switching devices, as well as improve the system dynamic performance. In the proposed control method, the DAB and inverter are coordinated to control the DC-link voltage and the power......, and this responsibility sharing control can effectively suppress the impact of the power variation on the DC-link voltage, without sacrificing stability. The proposed control method is also effective for DABCI in unidirectional power transmission. The effectiveness of the propose control has been validated by both...

  13. Prediction of Pollution Flashover Voltage Based on Leakage Current Under AC Operating Voltage

    Institute of Scientific and Technical Information of China (English)

    MEI Hongwei; WANG Liming; GUAN Zhicheng; MAO Yingke

    2012-01-01

    This paper presented a model to predict the AC flashover voltage of contaminated suspension insulators.The prediction method is based on the maximum leakage current under AC operating voltage.Three kinds of widely used suspension insulators were tested in various contamination states such as pollution layers with different equivalent salt deposit density(ESDD),different composition of the conductive components,different non-soluble deposit density(NSDD) and different pollution distribution states to simulate the contamination states in nature.The effective ESDD was proposed and calculated.Influences of contamination states to maximum leakage current and flashover voltage were studied.Then,the relationships between flashover voltage and leakage current in these states were presented.Finally,considering the difference of insulator profiles,a new parameter is defined and a model to estimate the flashover voltage based on this parameter is developed.The model could be used in all kinds of suspension insulators in different contamination states and was validated by the test results.

  14. Critical current densities estimated from AC susceptibilities in proximity-induced superconducting matrix of multifilamentary wire

    Science.gov (United States)

    Akune, Tadahiro; Sakamoto, Nobuyoshi

    2009-03-01

    In a multifilamentary wire proximity-currents between filaments show a close resemblance with the inter-grain current in a high-Tc superconductor. The critical current densities of the proximity-induced superconducting matrix Jcm can be estimated from measured twist-pitch dependence of magnetization and have been shown to follow the well-known scaling law of the pinning strength. The grained Bean model is applied on the multifilamentary wire to obtain Jcm, where the filaments are immersed in the proximity-induced superconducting matrix. Difference of the superconducting characteristics of the filament, the matrix and the filament content factor give a variety of deformation on the AC susceptibility curves. The computed AC susceptibility curves of multifilamentary wires using the grained Bean model are favorably compared with the experimental results. The values of Jcm estimated from the susceptibilities using the grained Bean model are comparable to those estimated from measured twist-pitch dependence of magnetization. The applicability of the grained Bean model on the multifilamentary wire is discussed in detail.

  15. Critical current densities estimated from AC susceptibilities in proximity-induced superconducting matrix of multifilamentary wire

    Energy Technology Data Exchange (ETDEWEB)

    Akune, Tadahiro; Sakamoto, Nobuyoshi, E-mail: akune@te.kyusan-u.ac.j [Department of Electrical Engineering and Information Technology, Kyushu Sangyo University, 2-3-1 Matsukadai, Fukuoka 813-8503 (Japan)

    2009-03-01

    In a multifilamentary wire proximity-currents between filaments show a close resemblance with the inter-grain current in a high-T{sub c} superconductor. The critical current densities of the proximity-induced superconducting matrix J{sub cm} can be estimated from measured twist-pitch dependence of magnetization and have been shown to follow the well-known scaling law of the pinning strength. The grained Bean model is applied on the multifilamentary wire to obtain J{sub cm}, where the filaments are immersed in the proximity-induced superconducting matrix. Difference of the superconducting characteristics of the filament, the matrix and the filament content factor give a variety of deformation on the AC susceptibility curves. The computed AC susceptibility curves of multifilamentary wires using the grained Bean model are favorably compared with the experimental results. The values of J{sub cm} estimated from the susceptibilities using the grained Bean model are comparable to those estimated from measured twist-pitch dependence of magnetization. The applicability of the grained Bean model on the multifilamentary wire is discussed in detail.

  16. Emergency operation of a 3AC 50Hz power grid in the Loetschberg base tunnel; Notbetrieb der Energieversorgung 3AC 50Hz im Loetschberg-Basistunnel

    Energy Technology Data Exchange (ETDEWEB)

    Stadelmann, M. [BLS AG, Ressort Bahnstrom, Bern (Switzerland); Boss, J. [BKW FMB Energie AG, Spiez (Switzerland)

    2007-11-15

    At latest after 90 min after tripping of the normal supply a special isle grid energized from the power plant of Kandergrund feeds the numerous users in the base tunnel with 3 AC 50 hz. This prevents them from damages and train operation can be assured immediately after return of normal grid voltage. (orig.)

  17. The influence of microwave irradiation power on current voltage characteristics of intrinsic Josephson junctions

    Science.gov (United States)

    Shukrinov, Yu M.; Mans, M.; Scherbel, J.; Seidel, P.

    2007-02-01

    The current-voltage characteristics of a micrometre bridge of intrinsic Josephson junctions under microwave irradiation are studied. The collective switching of the group of four junctions splits up as the AC signal amplitude is gradually increased. The switching current of the remaining group of junctions is increased with increasing radiation power. We consider that microwave irradiation injects an additional quasiparticle current into the Josephson junction array. We use ideas of breakdown of quasineutrality and quasiparticle charge imbalance in the superconducting layers and explain the experimental results by the competition between the 'current effect' and the effect of suppression of the switching current by irradiation.

  18. The influence of microwave irradiation power on current-voltage characteristics of intrinsic Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Shukrinov, Yu M [BLTP, JINR, Dubna, Moscow Region, 141980 (Russian Federation); Mans, M [Institut fur Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, D-07743 Jena (Germany); Scherbel, J [Institut fur Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, D-07743 Jena (Germany); Seidel, P [Institut fur Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, D-07743 Jena (Germany)

    2007-02-15

    The current-voltage characteristics of a micrometre bridge of intrinsic Josephson junctions under microwave irradiation are studied. The collective switching of the group of four junctions splits up as the AC signal amplitude is gradually increased. The switching current of the remaining group of junctions is increased with increasing radiation power. We consider that microwave irradiation injects an additional quasiparticle current into the Josephson junction array. We use ideas of breakdown of quasineutrality and quasiparticle charge imbalance in the superconducting layers and explain the experimental results by the competition between the 'current effect' and the effect of suppression of the switching current by irradiation.

  19. Modeling a reversible solid oxide fuel cell as a storage device within AC power networks

    Energy Technology Data Exchange (ETDEWEB)

    Ren, J.; Roscoe, A.J.; Burt, G. [Department of Electronic and Electrical Engineering, Royal College, University of Strathclyde, Glasgow (United Kingdom); Gamble, S.R.; Irvine, J.T.S. [School of Chemistry, University of St. Andrews, Purdie Building, St. Andrews (United Kingdom)

    2012-10-15

    A reversible solid oxide fuel cell (RSOFC) system, consisting of a RSOFC stack, heat store, and electrical inverters to convert DC to AC power, is shown by computer modeling to have the potential to efficiently store electrical energy. This paper describes the modeling of a single RSOFC, based on a proposed cell geometry, empirical data on the resistivities of the components, and calculation of activation and diffusion polarization resistances from electrochemical theory. Data from ac impedance spectroscopy measurements on symmetrical cells are used to model RSOFC impedance. A RSOFC stack is modeled by electrically linking the individual cells inside a pressurized vessel. A phase change heat store is added to improve energy storage efficiency. The model is implemented in MATLAB {sup registered} /Simulink {sup registered}. Two competing inverter control schemes are compared, trading off DC bus ripple against AC power quality. It is found that selection of appropriate DC bus capacitance is important in certain scenarios, with potential system cost implications. It is shown that the system can store electrical energy at an efficiency of 64% over a single discharge-charge cycle, i.e., hydrogen to electricity and heat to hydrogen. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Sub-micrometer particles produced by a low-powered AC electric arc in liquids.

    Science.gov (United States)

    Jaworski, Jacek A; Fleury, Eric

    2012-01-01

    The article presents the report of the production of composites of sub-micrometer metal particles in matrix consisted of the metal compounds by means of an AC electric arc in water and paraffin solutions using electrodes carbon-metal and metal-metal (metal: Ni, Fe, Co, Cu). The advantage of this method is the low electric power (from 5 to 10 W) needed in comparison to standard DC arc-discharge methods (0.8 to 3 kW). This method enables the production of particles from conductive material also in wide range of temperature and in solvent which could be either transparent to light or opaque. Moreover the solvent can be electrolyte or insulating liquid. The microstructure of the composite layer was investigated by scanning electron microscopy (SEM), Electron Probe Microanalysis (EPMA) and X-ray. During particles production in water metal oxides were created. Additionally using cobalt-copper, nickel-copper as couple electrodes, insoluble in water copper (II) hydroxide crystal grains were created additionally which crystals shape was depended on transition metal. For iron-copper couple electrodes system the copper (II) hydroxide was not formed. Experiments with sequence production of Ni and Fe particles with C electrode assisting in molten paraffin let to obtain both Ni and Fe particles surrounded by paraffin. After solidification the material was insulator but if locally magnetic field influenced on the liquid solution in that place after solidification a new composite was created which was electric current conductor with resistivity around 0.1 omega x m, was attracted by magnetic field and presented magneto resistance around 0.4% in changing magnetic field in a range 150 mT. After mixing the concentrated paraffin with normal paraffin resistivity of the mixture increased and it became photosensitive and created small voltage under light influence.

  1. AC Power Routing System in Home Based on Demand and Supply Utilizing Distributed Power Sources

    Directory of Open Access Journals (Sweden)

    Takashi Hikihara

    2011-04-01

    Full Text Available To help reduce consumption of fossil fuels, renewable, natural and distributed power sources are being adopted. These alternative energy sources inevitably show fluctuations in the amount of output power, frequency, and voltage. The suppression of such fluctuations is a key issue to avoid disturbances in power grids. A similar situation arises as far as the regulation of in-home power flow is concerned. We focus on the quality of supplied and demanded power in particular. In this paper, an in-home power distribution system based on information of power is proposed. The system is developed in order to integrate power dispatch and communication. The experimental results show the feasibility of new flexible and efficient power management approaches.

  2. Study on Transformer Magnetic Biasing Control Method for AC Power Supplies

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper presents a novel transformer magnetic biasing control method for high-power high-performance AC power supplies. Serious consequences due to magnetic biasing and several methods to overcome magnetic biasing are first discussed. The causes of the transformer magnetic biasing are then analyzed in detail. The proposed method is based on a high-pass filter inserted in the forward path and the feedforward control. Without testing magnetic biasing of transformer, this method can eliminate magnetic biasing of transformer completely in real-time waveform feedback control systems though the aero error of the Hall effect sensors varies with time and temperature. The method has already been employed in a 90KVA AC power supply. It is shown that it offers improved performance over existing ones. In this method, no sensors are used such that the zero error of the Hall effect sensors has not any influence on the system. It is simple to design and implement. Furthermore, the method is suitable for various power applications.

  3. Effect of the combined action of Faradaic currents and mobility differences in ac electro-osmosis

    Science.gov (United States)

    González, A.; Ramos, A.; García-Sánchez, P.; Castellanos, A.

    2010-01-01

    In this work, we extend previous analyses of ac electro-osmosis to account for the combined action of two experimentally relevant effects: (i) Faradaic currents from electrochemical reactions at the electrodes and (ii) differences in ion mobilities of the electrolyte. In previous works, the ac electro-osmotic motion has been analyzed theoretically under the assumption that only forces in the diffuse (Debye) layer are relevant. Here, we first show that if the ion mobilities of a 1-1 aqueous solution are different, the charged zone expands from the Debye layer to include the diffusion layer. We later include the Faradaic currents and, as an attempt to explore both factors simultaneously, we perform a thin-layer, low-frequency, linear analysis of the system. Finally, the model is applied to the case of an electrolyte actuated by a traveling-wave signal. A steady liquid motion in opposite direction to the applied signal is predicted for some ranges of the parameters. This could serve as a partial explanation for the observed flow reversal in some experiments.

  4. Fractional Modeling of the AC Large-Signal Frequency Response in Magnetoresistive Current Sensors

    Directory of Open Access Journals (Sweden)

    Sergio Iván Ravelo Arias

    2013-12-01

    Full Text Available Fractional calculus is considered when derivatives and integrals of non-integer order are applied over a specific function. In the electrical and electronic domain, the transfer function dependence of a fractional filter not only by the filter order n, but additionally, of the fractional order α is an example of a great number of systems where its input-output behavior could be more exactly modeled by a fractional behavior. Following this aim, the present work shows the experimental ac large-signal frequency response of a family of electrical current sensors based in different spintronic conduction mechanisms. Using an ac characterization set-up the sensor transimpedance function  is obtained considering it as the relationship between sensor output voltage and input sensing current,[PLEASE CHECK FORMULA IN THE PDF]. The study has been extended to various magnetoresistance sensors based in different technologies like anisotropic magnetoresistance (AMR, giant magnetoresistance (GMR, spin-valve (GMR-SV and tunnel magnetoresistance (TMR. The resulting modeling shows two predominant behaviors, the low-pass and the inverse low-pass with fractional index different from the classical integer response. The TMR technology with internal magnetization offers the best dynamic and sensitivity properties opening the way to develop actual industrial applications.

  5. The AC (Alternating Current) Electrical Behavior of Multi-layered Thermoelectric Devices

    Science.gov (United States)

    Alim, Mohammad A.; Budak, Satilmis; Bhattacharjee, Sudip

    2016-11-01

    In this study the ac (alternating current) small-signal electrical data in the frequency range 5 Hz ≤ f ≤ 13 MHz are obtained for the multi-layered thermoelectric (TE) devices to extract underlying operative mechanisms via an equivalent circuit model. This model is developed from the complex plane plots in conjunction with the Bode plot. It is observed that the inductive behavior is prevalent for both unbombarded and bombarded TE devices regardless of the doses as both types are observed as somewhat weak in thermoelectric properties. The bombarded multi-layered devices followed a systematic pattern in ac behavior via semicircular relaxation both in the impedance and admittance planes for the same measured data. This pattern is attributed to the transition from one lumped behavior to two distinct mechanisms. It is observed that the conductive nature of the equivalent circuit model via non-blocking (non-capacitive) elements, attributed to the underlying operative electrical paths between the two opposite electrodes across the multi-layered device exists, satisfying direct current conditions of the equivalent circuit model. The inductive behavior at high frequencies originates from the conductive aspect of the lumped response of the device in addition to the contribution of the electrode leads. Thus, the proposed equivalent circuit model contains external inductance that verifies a meaningful representation of the multi-layered TE device, though weak in thermoelectric properties.

  6. Shunt capacitors for a.c. power systems having a rated voltage above 1000 V - Part 1: General

    CERN Document Server

    International Electrotechnical Commission. Geneva

    2005-01-01

    This part of IEC 60871 is applicable to both capacitor units and capacitor banks intended to be used, particularly, for power-factor correction of a.c. power systems having a rated voltage above 1 000 V and frequencies of 15 Hz to 60 Hz. This part of IEC 60871 also applies to capacitors intended for use in power filter circuits.

  7. Power-Based Control for a Bidirectional AC-DC Power Converter

    NARCIS (Netherlands)

    del Puerto Flores, Dunstano; Scherpen, Jacquelien M.A.

    2011-01-01

    In many electrical applications it is indispensable that the power converter can operate as a generating or rectifier unit, and the controller must be able to handle this bidirectional power flow. An application example is the doubly fed induction machine, where power can flow in both directions thr

  8. Proposal and Development of a High Voltage Variable Frequency Alternating Current Power System for Hybrid Electric Aircraft

    Science.gov (United States)

    Sadey, David J.; Taylor, Linda M.; Beach, Raymond F.

    2017-01-01

    The development of ultra-efficient commercial vehicles and the transition to low-carbon emission propulsion are seen as strategic thrust paths within NASA Aeronautics. A critical enabler to these paths comes in the form of hybrid electric propulsion systems. For megawatt-class systems, the best power system topology for these hybrid electric propulsion systems is debatable. Current proposals within NASA and the Aero community suggest using a combination of alternating current (AC) and direct current (DC) for power generation, transmission, and distribution. This paper proposes an alternative to the current thought model through the use of a primarily high voltage AC power system, supported by the Convergent Aeronautics Solutions (CAS) Project. This system relies heavily on the use of doubly-fed induction machines (DFIMs), which provide high power densities, minimal power conversion, and variable speed operation. The paper presents background on the activity along with the system architecture, development status, and preliminary results.

  9. A Series-LC-Filtered Active Damper with Grid Disturbance Rejection for AC Power-Electronics-Based Power Systems

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Pang, Ying; Loh, Poh Chiang;

    2015-01-01

    damper. Unlike an active power filter for mitigating low-frequency harmonics, the proposed damper dampens resonances at higher frequencies, whose values are dependent on interactions among multiple grid-connected converters and reactive elements of the system. Its control requirements are, therefore......-order resonant controller, in addition to the second-order resonant controller used for resonance damping. Experimental results obtained have confirmed the effectiveness of these controllers, and hence, the feasibility of the active damper.......This letter proposes an active damper with a series LC filter for suppressing resonances in an ac power-electronics-based power system. The added series filter capacitor helps to withstand most of the system voltage, hence, allowing a lower rated converter to be used for implementing the active...

  10. A novel power control strategy of Modular Multi-level Converter in HVDC-AC hybrid transmission systems for passive networks

    DEFF Research Database (Denmark)

    Hu, Zhenda; Wu, Rui; Yang, Xiaodong;

    2014-01-01

    With the development of High Voltage DC Transmission (HVDC) technology, there will be more and more HVDC-AC hybrid transmission system in the world. A basic challenge in HVDC-AC hybrid transmission systems is to optimize the power sharing between DC and AC lines, which become more severe when...... supplying power for passive networks, as the surplus power can only flow back to power grids through the AC lines. To deal with this issue, it demands not only accurate system capability design but also flexible power control strategy of power converters in VSC-HVDC. This paper proposes a novel power...

  11. Modeling and Simulation Analysis of Power Frequency Electric Field of UHV AC Transmission Line

    Directory of Open Access Journals (Sweden)

    Chen Han

    2015-02-01

    Full Text Available In order to study the power frequency electric field of UHV AC transmission lines, this paper which models and calculates using boundary element method simulates various factors influencing the distribution of the power frequency electric field, such as the conductor arrangement, the over-ground height, the split spacing and the sub conductor radius. Different influence of various factors on the electric field distribution will be presented. In a single loop, using VVV triangular arrangement is the most secure way; in a dual loop, the electric field intensity using reverse phase sequence is weaker than that using positive phase sequence. Elevating the over-ground height and reducing the conductor split spacing will both weaken the electric field intensity, while the change of sub conductor radius can hardly cause any difference. These conclusions are important for electric power company to detect circuit.

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

    Science.gov (United States)

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

    2013-11-01

    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.

  13. Power Flow Analysis for Low-Voltage AC and DC Microgrids Considering Droop Control and Virtual Impedance

    DEFF Research Database (Denmark)

    Li, Chendan; Chaudhary, Sanjay Kumar; Savaghebi, Mehdi

    2017-01-01

    adequate power flow studies. In this paper, power flow analyses for both AC and DC microgrids are formulated and implemented. The mathematical models for both types of microgrids considering the concept of virtual impedance are used to be in conformity with the practical control of the distributed...... generators. As a result, calculation accuracy is improved for both AC and DC microgrid power flow analyses, comparing with previous methods without considering virtual impedance. Case studies are conducted to verify the proposed power flow analyses in terms of convergence and accuracy. Investigation...

  14. Enhancing power transfer capability through flexible AC transmission system devices:a review

    Institute of Scientific and Technical Information of China (English)

    Fadi M ALBATSH; Saad MEKHILEF; Shameem AHMAD; H MOKHLIS; M A HASSAN

    2015-01-01

    Global demand for power has significantly increased, but power generation and transmission capacities have not increased proportionally with this demand. As a result, power consumers suffer from various problems, such as voltage and frequency instability and power quality issues. To overcome these problems, the capacity for available power transfer of a transmission network should be enhanced. Researchers worldwide have addressed this issue by using flexible AC transmission system (FACTS) devices. We have conducted a comprehensive review of how FACTS controllers are used to enhance the avail-able transfer capability (ATC) and power transfer capability (PTC) of power system networks. This review includes a discussion of the classification of different FACTS devices according to different factors. The popularity and applications of these devices are discussed together with relevant statistics. The operating principles of six major FACTS devices and their application in increasing ATC and PTC are also presented. Finally, we evaluate the performance of FACTS devices in ATC and PTC im-provement with respect to different control algorithms.

  15. Space Weather Effects on Current and Future Electric Power Systems

    Science.gov (United States)

    Munoz, D.; Dutta, O.; Tandoi, C.; Brandauer, W.; Mohamed, A.; Damas, M. C.

    2016-12-01

    This work addresses the effects of Geomagnetic Disturbances (GMDs) on the present bulk power system as well as the future smart grid, and discusses the mitigation of these geomagnetic impacts, so as to reduce the vulnerabilities of the electric power network to large space weather events. Solar storm characterized by electromagnetic radiation generates geo-electric fields that result in the flow of Geomagnetically Induced Currents (GICs) through the transmission lines, followed by transformers and the ground. As the ground conductivity and the power network topology significantly vary with the region, it becomes imperative to estimate of the magnitude of GICs for different places. In this paper, the magnitude of GIC has been calculated for New York State (NYS) with the help of extensive modelling of the whole NYS electricity transmission network using real data. Although GIC affects only high voltage levels, e.g. above 300 kV, the presence of coastline in NYS makes the low voltage transmission lines also susceptible to GIC. Besides this, the encroachment of technologies pertaining to smart grid implementation, such as Phasor Measurement Units (PMUs), Microgrids, Flexible AC Transmission System (FACTS), and Information and Communication Technology (ICT) have been analyzed for GMD impacts. Inaccurate PMU results due to scintillation of GPS signals that are affected by electromagnetic interference of solar storm, presence of renewable energy resources in coastal areas that are more vulnerable to GMD, the ability of FACTS devices to either block or pave new path for GICs and so on, shed some light on impacts of GMD on smart grid technologies.

  16. Current measurement method for characterization of fast switching power semiconductors with Silicon Steel Current Transformer

    DEFF Research Database (Denmark)

    Li, Helong; Beczkowski, Szymon; Munk-Nielsen, Stig

    2015-01-01

    This paper proposes a novel current measurement method with Silicon Steel Current Transformer (SSCT) for the characterization of fast switching power semiconductors. First, the existing current sensors for characterization of fast switching power semiconductors are experimentally evaluated...

  17. Optimal PowerFlow (OPF) Model with Unified AC-DC Load Flow and Optimal Commitmentfor an AC-catenary Railway Power Supply System (RPSS) fed by aHigh Voltage DC (HVDC) transmission line

    OpenAIRE

    Abrahamsson, Lars; Östlund, Stefan; Söder, Lennart

    2012-01-01

    In this paper an alternative railway power systems design based on an HVDC feeder is studied. The HVDC feeder is connected to the catenary by converters. Such an HVDC line is also appropriate for DC-fed railways and AC-fed railways working at public frequency. A unit commitment optimal power flow model has been developed and is applied on a test system. In this paper, the model is presented in detail. The model, in the form of an MINLP program, uses unified AC-DC power flow to minimize the en...

  18. Sensitivity Analysis of Core Damage by Loss of Auxiliary Feed Water during the Extended Loss of All AC Power

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Woo Jae; Chung, Soon Il; Hwang, Su Hyun; Lee, Kyung Jin; Lee, Byung Chul [FNC Tech., Yongin (Korea, Republic of); Yun, Duk Joo; Lee, Seung Chan [Korea Hydro and Nuclear Power Co. Ltd., Daejeon (Korea, Republic of)

    2015-10-15

    In this study, the reactor core damage time for OPR1000 type Nuclear Power Plant (NPP) was analyzed to develop a strategy to handle ELAP and to apply to the EOP. The reactor core damage time in the ELAP condition was calculated according to the time of Auxiliary Feedwater (AFW) loss. Fukushima accident was caused by long hours of Station Black Out (SBO) caused by natural disaster beyond Design Based Accident (DBA) criteria. It led to the reactor core damage. After the accident, the regulatory authorities of each country (Japan, US, EU, IAEA, and etc.) recommended developing the necessary systems and strategies in order to cover up the Extended Loss of All AC Power (ELAP) such as one occurred in the Fukushima accident. And the need of procedure or guideline to cope with ELAP has been raised through the stress test for Wolsong Nuclear Power Plant unit 1. Current Emergency Operating Procedures (EOP) used in domestic nuclear power plant are seemed to be insufficient to cope with ELAP. Therefore, it has been required to be improved. As the result, the time of AFW loss in the ELAP condition influences greatly on core damage time.

  19. Plasma characteristics of argon glow discharge produced by AC power supply operating at low frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Kongpiboolkid, Watcharapon; Mongkolnavin, Rattachat [Department of Physics, Facuty of Science, Chulalongkorn University, Bangkok (Thailand); Plasma Technology and Nuclear Fusion Research Unit, Chulalongkorn University, Bangkok (Thailand)

    2015-04-24

    Non-thermal properties of Argon glow discharge operating with various operating pressures were measured and presented in this work. The Argon plasma is produced by a parallel conducting electrodes coupling with a high voltage AC power supply. The power supply can generate high AC voltage at various frequencies. The frequencies for the operation are in the range of a few kHz. The system is capable of generating electric field between the two metal electrodes discharge system. The characteristics of plasma produced were measured by optical emission spectroscopy (OES) technique where electron temperature (T{sub e}) and electron number density (n{sub e}) can be determined by line intensity ratio method. The value of electron number density was then determined from the Saha-Eggert equation. Our results show that the electron number density of the discharge obtained is of the order of 10{sup −17} − 10{sup −18} m{sup −3} where the electron temperature is between 1.00−2.00 eV for various operating frequencies used which are in good agreement with similar results published earlier.

  20. A self-powered AC magnetic sensor based on piezoelectric nanogenerator.

    Science.gov (United States)

    Yu, Aifang; Song, Ming; Zhang, Yan; Kou, Jinzong; Zhai, Junyi; Lin Wang, Zhong

    2014-11-14

    An AC magnetic field, which is a carrier of information, is distributed everywhere and is continuous. How to use and detect this field has been an ongoing topic over the past few decades. Conventional magnetic sensors are usually based on the Hall Effect, the fluxgate, a superconductor quantum interface or magnetoelectric or magnetoresistive sensing. Here, a flexible, simple, low-cost and self-powered active piezoelectric nanogenerator (NG) is successfully demonstrated as an AC magnetic field sensor at room temperature. The amplitude and frequency of a magnetic field can both be accurately sensed by the NG. The output voltage of the NG has a good linearity with a measured magnetic field. The detected minute magnetic field is as low as 1.2 × 10(-7) tesla, which is 400 times greater than a commercial magnetic sensor that uses the Hall Effect. In comparison to the existing technologies, an NG is a room-temperature self-powered active sensor that is very simple and very cheap for practical applications.

  1. ACS production: optimal design of solar thermal power plants; Produccion de ACS. Optimizacion del dimensionado de instalaciones de energia solar termica

    Energy Technology Data Exchange (ETDEWEB)

    Platon Arias, L.; San Jose Alonso, F.

    2009-07-01

    The aim of this project is to develop a program to size solar thermal power plants for the production of the company ACS, which enable optimum value calculations of the different influence parameters (surface, inclination, orientation, energy input) advising diverse circumstances and requirements. The energy input calculation has been effected according to f-chart method. For the solar radiation on inclined and oriented surfaces calculation, has been applied the Klein Method. (Author) 14 refs.

  2. Ag incorporated Mn3O4/AC nanocomposite based supercapacitor devices with high energy density and power density.

    Science.gov (United States)

    Nagamuthu, S; Vijayakumar, S; Muralidharan, G

    2014-12-14

    Silver incorporated Mn3O4/amorphous carbon (AC) nanocomposites are synthesized by a green chemistry method. X-ray diffraction studies revealed the structural changes in Mn3O4/AC nanocomposites attributable to the addition of silver. Cyclic voltammetry, charge-discharge and ac-impedance studies indicated that the Ag-Mn3O4/AC-5 electrode was the most suitable candidate for supercapacitor applications. From the galvanostatic charge-discharge studies, a higher specific capacitance of 981 F g(-1) at a specific current of 1 A g(-1) was obtained. An Ag-Mn3O4/AC-symmetric supercapacitor consisting of an Ag-incorporated Mn3O4/AC composite as an anode as well as a cathode, and an asymmetric supercapacitor consisting of an Ag-incorporated Mn3O4/AC composite as a cathode and an activated carbon as an anode have been fabricated. The symmetric device exhibits a specific cell capacitance of 72 F g(-1) at a specific current of 1 A g(-1) whereas the asymmetric device delivers a specific cell capacitance of 180 F g(-1) at a high current rate of 10 A g(-1). The asymmetric supercapacitor device yields a high energy density of 81 W h kg(-1). This is higher than that of lead acid batteries and comparable with that of nickel hydride batteries.

  3. Six switches solution for single-phase AC/DC/AC converter with capability of second-order power mitigation in DC-link capacitor

    DEFF Research Database (Denmark)

    Liu, Xiong; Wang, Peng; Loh, Poh Chiang

    2011-01-01

    /DC rectifier and DC/AC inverter. A small size DC-link capacitor can be achieved through coordination control of rectifier and inverter to cancel the second-order oscillation power. Maximum available phase difference between rectifier’s and inverter’s modulation references is investigated to be dependent...... on their modulation indices of the six-switch converter, and high modulation indices are proved to be feasible for second-order power cancellation in the DC-link based on the phase difference analysis. Both reduced switch numbers and DC electrolytic capacitor size can be achieved using the proposed converter...

  4. A GPS-Based Control Framework for Accurate Current Sharing and Power Quality Improvement in Microgrids

    DEFF Research Database (Denmark)

    Golsorkhi, Mohammad; Savaghebi, Mehdi; Lu, Dylan;

    2016-01-01

    consensus protocol to ensure proportional sharing of average power. The voltage conditioning scheme produces compensation signals at fundamental and dominant harmonics to improve the voltage quality at a sensitive load bus. Experimental results are presented to validate the efficacy of the proposed method.......This paper proposes a novel hierarchical control strategy for improvement of load sharing and power quality in ac microgrids. This control framework is composed of a droop based controller at the primary level, and a combination of distributed power sharing and voltage conditioning schemes...... dynamic response. The droop coefficient, which acts as a virtual resistance is adaptively changed as a function of the peak current. This strategy not only simplifies the control design but also improves the current sharing accuracy at high loading conditions. The distributed power sharing scheme uses...

  5. Development of a single-phase harmonic power flow program to study the 20 kHz AC power system for large spacecraft

    Science.gov (United States)

    Kraft, L. Alan; Kankam, M. David

    1991-01-01

    The development of software is described to aid in design and analysis of AC power systems for large spacecraft. The algorithm is an important version of harmonic power flow program, HARMFLO, used for the study of AC power quality. The new program is applicable to three-phase systems typified by terrestrial power systems, and single-phase systems characteristic of space power systems. The modified HARMFLO accommodates system operating frequencies ranging from terrestrial 60 Hz to and beyond aerospace 20 kHz, and can handle both source and load-end harmonic distortions. Comparison of simulation and test results of a representative spacecraft power system shows a satisfactory correlation. Recommendations are made for the direction of future improvements to the software, to enhance its usefulness to power system designer and analysts.

  6. Integrated analysis of DFIG drive-train and power electronics dynamics during electrical AC faults and wind disturbances

    DEFF Research Database (Denmark)

    Barahona Garzón, Braulio; Sørensen, Poul Ejnar; Anaya-Lara, Olimpo

    2013-01-01

    The dynamics of a 2 MW DFIG wind turbine are studied during electrical AC faults, and wind disturbances. A simulation platform that couples HAWC2, and Matlab/Simulink was used. High frequencies of the gear box, and power electronics are neglected. It was shown that the dynamics of the dc-link are......The dynamics of a 2 MW DFIG wind turbine are studied during electrical AC faults, and wind disturbances. A simulation platform that couples HAWC2, and Matlab/Simulink was used. High frequencies of the gear box, and power electronics are neglected. It was shown that the dynamics of the dc...

  7. Automatic Control Systems (ACS for Generation and Sale of Electric Power Under Conditions of Industry-Sector Liberalization

    Directory of Open Access Journals (Sweden)

    Yu. Petrusha

    2013-01-01

    Full Text Available Possible risks pertaining to transition of electric-power industry to market relations have been considered in the paper. The paper presents an integrated ACS for generation and sale of electric power as an improvement of methodology for organizational and technical management. The given system is based on integration of operating Automatic Dispatch Control System (ADCS and developing Automatic Electricity Meter Reading System (AEMRS. The paper proposes to form an inter-branch sector of ACS PLC (Automatic Control System for Prolongation of Life Cycle users which is oriented on provision of development strategy.

  8. Analytical Analysis and Case Study of Transient Behavior of Inrush Current in Power Transformer for Designing of Efficient Circuit Breakers

    Science.gov (United States)

    Harmanpreet, Singh, Sukhwinder; Kumar, Ashok; Kaur, Parneet

    2010-11-01

    Stability & security are main aspects in electrical power systems. Transformer protection is major issue of concern to system operation. There are many mall-trip cases of transformer protection are caused by inrush current problems. The phenomenon of transformer inrush current has been discussed in many papers since 1958. In this paper analytical analysis of inrush current in a transformer switched on dc and ac supply has been done. This analysis will help in design aspects of circuit breakers for better performance.

  9. Current status of pacemaker power sources.

    Science.gov (United States)

    Tyers, G F; Brownlee, R R

    1978-06-01

    After years during which pacers of very similar design and capabilities were provided by a small number of manufactures, many different lithium, halogen, rechargeable, and nuclear power sources are now available. The variety of chemistries, methods of construction, and sealing techniques used in the batteries of the different manufacturers is almost unlimited. This has made it necessary for physicians who implant and follow pacer to acquire a general knowledge of the field if they are to make an informed choice of pacemaker power source for implantation and if they are to manage recalls with a minimum of patient and physician trauma. More experience is required before it can be definitely determined which of the new pacer power sources will prove superior, but when coupled with well-designed, hermetically sealed pulse generators, all are capable of providing continuous pacing for at least 5 years and the 10-year pacemaker is now a probability.

  10. DC current and AC impedance measurements on boron-doped single crystalline diamond films

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Haitao; Gaudin, O.; Jackman, R.B. [Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom); Muret, P.; Gheeraert, E. [Laboratoire d' Etudes des Proprietes Electroniques des Solides, BP166, 38042 Grenoble Cedex 9 (France)

    2003-09-01

    In this paper, we report the first measurement of impedance on boron-doped single crystalline diamond films from 0.1 Hz to 10 MHz with the temperature ranging from -100 C up to 300 C. The Cole-Cole (Z' via Z{sup ''}) plots are well fitted to a RC parallel circuit model and the equivalent Resistance and Capacitance for the diamond films have been estimated using the Zview curve fitting. The results show only one single semicircle response at each temperature measured. It was found that the resistance decreases from 70 G{omega} at -100 C to 5 k{omega} at 300 C. The linear curve fitting from -100 C to 150 C shows the sample has an activation energy of 0.37 eV, which is consistent with the theoretical value published of this kind of material. The equivalent capacitance is maintained at the level of pF up to 300 C suggesting that no grain boundaries are being involved, as expected from a single crystal diamond. The activation energy from the dc current-temperature curves is 0.36 eV, which is consistent with the value from ac impedance. The potential of this under-used technique for diamond film analysis will be discussed. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Micro Analyses AC/DC Hybrid Power Grid Planning and Design%交直流混合微电网的规划设计

    Institute of Scientific and Technical Information of China (English)

    王红阳

    2016-01-01

    由于交直流混合微电网可以减少多重变换器运行所产生的损耗、谐波电流,同时能够提高系统的经济性、可靠性,所以现在已成为当今微电网的主要发展方向。笔者将从电压等级、接地方式、母线结构和网络拓扑等角度,探讨交直流混合微电网的规划设计,以供有意对交直流混合微电网进行深入研究的专家学者参考。%Due to micro AC/DC hybrid power grid can reduce multiple converter loss, harmonic current generated by the operation, at the same time can improve the efficiency of system, the reliability, so now it is the main direction of micro grid today. Grounding method, the author will from voltage grade, bus structure and network topology of micro AC/DC hybrid power grid planning and design were discussed, for the intention to conduct the thorough research to the micro AC/DC hybrid power grid in the experts and scholars to provide the reference.

  12. Tevatron AC dipole system

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, R.; Kopp, S.E.; /Texas U.; Jansson, A.; Syphers, M.J.; /Fermilab

    2007-06-01

    The AC dipole is an oscillating dipole magnet which can induce large amplitude oscillations without the emittance growth and decoherence. These properties make it a good tool to measure optics of a hadron synchrotron. The vertical AC dipole for the Tevatron is powered by an inexpensive high power audio amplifier since its operating frequency is approximately 20 kHz. The magnet is incorporated into a parallel resonant system to maximize the current. The use of a vertical pinger magnet which has been installed in the Tevatron made the cost relatively inexpensive. Recently, the initial system was upgraded with a more powerful amplifier and oscillation amplitudes up to 2-3{sigma} were achieved with the 980 GeV proton beam. This paper discusses details of the Tevatron AC dipole system and also shows its test results.

  13. Uncertainty evaluation in the measurement of power frequency electric and magnetic fields from AC overhead power lines.

    Science.gov (United States)

    Ztoupis, I N; Gonos, I F; Stathopulos, I A

    2013-11-01

    Measurements of power frequency electric and magnetic fields from alternating current power lines are carried out in order to evaluate the exposure levels of the human body on the general public. For any electromagnetic field measurement, it is necessary to define the sources of measurement uncertainty and determine the total measurement uncertainty. This paper is concerned with the problems of measurement uncertainty estimation, as the measurement uncertainty budget calculation techniques recommended in standardising documents and research studies are barely described. In this work the total uncertainty of power frequency field measurements near power lines in various measurement sites is assessed by considering not only all available equipment data, but also contributions that depend on the measurement procedures, environmental conditions and characteristics of the field source, which are considered to increase the error of measurement. A detailed application example for power frequency field measurements is presented here by accredited laboratory.

  14. Active Distribution Grid Management based on Robust AC Optimal Power Flow

    DEFF Research Database (Denmark)

    Soares, Tiago; Bessa, Richard J.; Pinson, Pierre

    2017-01-01

    resources in day/hour-ahead stages. This paper follows the DSO trends by proposing a methodology for active grid management by which robust optimization is applied to accommodate spatial-temporal uncertainty. The proposed method entails the use of a multi-period AC-OPF, ensuring a reliable solution......Further integration of distributed renewable energy sources in distribution systems requires a paradigm change in grid management by the distribution system operators (DSO). DSOs are currently moving to an operational planning approach based on activating flexibility from distributed energy...... for the DSO. Wind and PV uncertainty is modeled based on spatial-temporal trajectories, while a convex hull technique to define uncertainty sets for the model is used. A case study based on real generation data allows illustration and discussion of the properties of the model. An important conclusion...

  15. An Examination of AC/HVDC Power Circuits for Interconnecting Bulk Wind Generation with the Electric Grid

    Directory of Open Access Journals (Sweden)

    Daniel Ludois

    2010-06-01

    Full Text Available The application of high voltage dc (HVDC transmission for integrating large scale and/or off-shore wind generation systems with the electric grid is attractive in comparison to extra high voltage (EHV ac transmission due to a variety of reasons. While the technology of classical current sourced converters (CSC using thyristors is well established for realization of large HVDC systems, the technology of voltage sourced converters (VSC is emerging to be an alternative approach, particularly suitable for multi-terminal interconnections. More recently, a more modular scheme that may be termed ‘bridge of bridge’ converters (BoBC has been introduced to realize HVDC systems. While all these three approaches are functionally capable of realizing HVDC systems, the converter power circuit design trade-offs between these alternatives are not readily apparent. This paper presents an examination of these topologies from the point of view of power semiconductor requirements, reactive component requirements, operating losses, fault tolerance, multi-terminal operation, modularity, complexity, etc. Detailed analytical models will be used along with a benchmark application to develop a comparative evaluation of the alternatives that maybe used by wind energy/bulk transmission developers for performing engineering trade-off studies.

  16. An examination of AC/HVDC power circuits for interconnecting bulk wind generation with the electric grid

    Energy Technology Data Exchange (ETDEWEB)

    Ludois, D.; Venkataramanan, G. [Department of Electrical and Computer Engineering, University of Wisconsin-Madison 1415 Engineering Dr. Madison WI 53706 (United States)

    2010-06-15

    The application of high voltage DC (HVDC) transmission for integrating large scale and/or off-shore wind generation systems with the electric grid is attractive in comparison to extra high voltage (EHV) AC transmission due to a variety of reasons. While the technology of classical current sourced converters (CSC) using thyristors is well established for realization of large HVDC systems, the technology of voltage sourced converters (VSC) is emerging to be an alternative approach, particularly suitable for multi-terminal interconnections. More recently, a more modular scheme that may be termed 'bridge of bridge' converters (BoBC) has been introduced to realize HVDC systems. While all these three approaches are functionally capable of realizing HVDC systems, the converter power circuit design trade-offs between these alternatives are not readily apparent. This paper presents an examination of these topologies from the point of view of power semiconductor requirements, reactive component requirements, operating losses, fault tolerance, multi-terminal operation, modularity, complexity, etc. Detailed analytical models will be used along with a benchmark application to develop a comparative evaluation of the alternatives that may be used by wind energy/bulk transmission developers for performing engineering trade-off studies. (author)

  17. Observer-based higher order sliding mode control of power factor in three-phase AC/DC converter for hybrid electric vehicle applications

    Science.gov (United States)

    Liu, Jianxing; Laghrouche, Salah; Wack, Maxime

    2014-06-01

    In this paper, a full-bridge boost power converter topology is studied for power factor control, using output higher order sliding mode control. The AC/DC converters are used for charging the battery and super-capacitor in hybrid electric vehicles from the utility. The proposed control forces the input currents to track the desired values, which can control the output voltage while keeping the power factor close to one. Super-twisting sliding mode observer is employed to estimate the input currents and load resistance only from the measurement of output voltage. Lyapunov analysis shows the asymptotic convergence of the closed-loop system to zero. Multi-rate simulation illustrates the effectiveness and robustness of the proposed controller in the presence of measurement noise.

  18. Suppression of AC railway power-line interference in ECG signals recorded by public access defibrillators

    Directory of Open Access Journals (Sweden)

    Dotsinsky Ivan

    2005-11-01

    Full Text Available Abstract Background Public access defibrillators (PADs are now available for more efficient and rapid treatment of out-of-hospital sudden cardiac arrest. PADs are used normally by untrained people on the streets and in sports centers, airports, and other public areas. Therefore, automated detection of ventricular fibrillation, or its exclusion, is of high importance. A special case exists at railway stations, where electric power-line frequency interference is significant. Many countries, especially in Europe, use 16.7 Hz AC power, which introduces high level frequency-varying interference that may compromise fibrillation detection. Method Moving signal averaging is often used for 50/60 Hz interference suppression if its effect on the ECG spectrum has little importance (no morphological analysis is performed. This approach may be also applied to the railway situation, if the interference frequency is continuously detected so as to synchronize the analog-to-digital conversion (ADC for introducing variable inter-sample intervals. A better solution consists of rated ADC, software frequency measuring, internal irregular re-sampling according to the interference frequency, and a moving average over a constant sample number, followed by regular back re-sampling. Results The proposed method leads to a total railway interference cancellation, together with suppression of inherent noise, while the peak amplitudes of some sharp complexes are reduced. This reduction has negligible effect on accurate fibrillation detection. Conclusion The method is developed in the MATLAB environment and represents a useful tool for real time railway interference suppression.

  19. Containment and Consensus-based Distributed Coordination Control for Voltage Bound and Reactive Power Sharing in AC Microgrid

    DEFF Research Database (Denmark)

    Han, Renke; Meng, Lexuan; Ferrari-Trecate, Giancarlo

    2017-01-01

    This paper offers a highly flexible and reliable control strategy to achieve voltage bounded regulation and accurate reactive power sharing coordinately in AC Micro-Grids. A containment and consensus-based distributed coordination controller is proposed, by which each output voltage magnitude can...

  20. Containment and Consensus-based Distributed Coordination Control for Voltage Bound and Reactive Power Sharing in AC Microgrid

    DEFF Research Database (Denmark)

    Han, Renke; Meng, Lexuan; Ferrari-Trecate, Giancarlo

    2017-01-01

    This paper offers a highly flexible and reliable control strategy to achieve voltage bounded regulation and accurate reactive power sharing coordinately in AC Micro-Grids. A containment and consensus-based distributed coordination controller is proposed, by which each output voltage magnitude can...

  1. Distributed Primary and Secondary Power Sharing in a Droop-Controlled LVDC Microgrid with Merged AC and DC Characteristics

    DEFF Research Database (Denmark)

    Peyghami Akhuleh, Saeed; Mokhtari, Hossein; Loh, Poh Chiang;

    2016-01-01

    in dc microgrids, which in most cases, are solved by a secondary control layer reinforced by an extensive communication network. To avoid such an infrastructure and its accompanied complications, this paper proposes an alternative droop scheme for low-voltage dc (LVDC) microgrid with both primary power......In an ac microgrid, a common frequency exists for coordinating active power sharing among droop-controlled sources. A common frequency is absent in a dc microgrid, leaving only the dc source voltages for coordinating active power sharing. That causes sharing error and poorer voltage regulation...... sharing and secondary voltage regulation merged. The main idea is to introduce a non-zero unifying frequency and a second power term to each dc source by modulating its converter with both a dc and a small ac signal. Two droop expressions can then be written for the proposed scheme, instead of the single...

  2. SINGLE PHASE HIGH FREQUENCY AC CONVERTER FOR INDUCTION HEATING APPLICATION

    Directory of Open Access Journals (Sweden)

    M.A INAYATHULLAAH,

    2010-12-01

    Full Text Available The proposed topology reduces the total harmonic distortion (THD of a high frequency AC/AC Converter well below the acceptable limit. This paper deals with a novel single phase AC/DC/AC soft switching utility frequency AC to high frequency AC converter. In this paper a single phase full bridge inverter with Vienna rectifier as front end is used instead of conventional diode bridge rectifier to provide continuous sinusoidal input current with nearly unity power factor at the source side with extremely low distortion.. This power converter is more suitable and acceptable for cost effective high frequency (HF consumer induction heating applications.

  3. Analysis and design of over-current limit control strategies applied in aeronautical power supplies

    Institute of Scientific and Technical Information of China (English)

    WANG Lin-bing; HE Xiang-ning

    2007-01-01

    Some Over-Current Limit Control strategies are analyzed and designed to meet the demands of high reliability and rapid dynamic response in the aeronautical power supply applications. The control schemes are both effective in DC-DC converters and DC-AC converters. Controller models are set up, and the over-current limit operation principles of analogy and digital control are analyzed too. An 800VA aeronautical power supply has been constructed to verify the performance of the proposed control strategy in various cases such as the sudden load change and the constant load. The analysis and experiments confirm the advantages of the proposed over-current limit strategies as follows: simple,effective and reliable.

  4. Impact of Negative Sequence Current Injection by Wind Power Plants

    DEFF Research Database (Denmark)

    Chaudhary, Sanjay; Göksu, Ömer; Teodorescu, Remus

    2013-01-01

    This paper presents an analysis of the impact from negative sequence current injection by wind power plants in power systems under steady-state and short-term unbalanced conditions, including faults. The separate positive and negative sequence current control capability of the grid-side converter...

  5. Surge currents and voltages at the low voltage power mains during lightning strike to a GSM tower

    Energy Technology Data Exchange (ETDEWEB)

    Markowska, Renata [Bialystok Technical University (Poland)], E-mail: remark@pb.edu.pl

    2007-07-01

    The paper presents the results of numerical calculations of lightning surge currents and voltages in the low voltage power mains system connected to a free standing GSM base station. Direct lightning strike to GSM tower was studied. The analysis concerned the current that flows to the transformer station through AC power mains, the potential difference between the grounding systems of the GSM and the transformer stations and the voltage differences between phase and PE conductors of the power mains underground cable at both the GSM and the transformer sides. The calculations were performed using a numerical program based on the electromagnetic field theory and the method of moments. (author)

  6. Ranking transmission projects in large scale systems using an AC power flow model; Priorizacao de obras em sistemas de grande porte usando um modelo AC da rede

    Energy Technology Data Exchange (ETDEWEB)

    Melo, A.C.G. [Centro de Pesquisas de Energia Eletrica (CEPEL), Rio de Janeiro, RJ (Brazil); Fontoura Filho, R.N. [ELETROBRAS, Rio de Janeiro, RJ (Brazil); Peres, L.A.P. Pecorelli [FURNAS, Rio de Janeiro, RJ (Brazil); Morozowski Filho, M. [Santa Catarina Univ., Florianopolis, SC (Brazil)

    1994-12-31

    Initially, this paper summarizes the approach developed by the Brazilian Planning Criteria Working Group (GTCP/ELETROBRAS) for identifying which subset of transmission investments should be postponed to meet a pre-stablished budget constraint with the least possible impact on system performance. Next, this paper presents the main features of the computational model PRIO, which allows the application of the ranking process to large scale power systems (2,000 buses and 3,000 circuits), with as many as 100 projects to be ranked. In this model, the adequacy analysis of each system state is carried out through an AC power flow coupled to a successive linear programming based remedial actions model. Case studies with the IEEE-RTS system and a configuration of the Brazilian Southeastern are presented and discussed. (author) 7 refs., 6 figs., 5 tabs.

  7. Thermal Impact Analysis of Circulating Current in High Power Modular Online Uninterruptible Power Supplies Application

    DEFF Research Database (Denmark)

    Zhang, Chi; Guerrero, Josep M.; Vasquez, Juan Carlos

    2015-01-01

    . In order to reduce system size and cost, each module shares the same DC and AC bus without any isolation or passive elements in the system. Consequently, potential zero-sequence current is possible to occur and should be paid specific attention. In this paper, a four-module online UPS system is designed....... And thermal and loss distribution condition are investigated under different circulating current condition with conventional three phase H-bridge topology....

  8. Nuclear Power for Sustainable Development : Current Status and Future Prospects

    OpenAIRE

    Adamantiades, A.; Kessides, I.

    2009-01-01

    Interest in nuclear power has been revived as a result of volatile fossil fuel prices, concerns about the security of energy supplies, and global climate change. This paper describes the current status and future plans for expansion of nuclear power, the advances in nuclear reactor technology, and their impacts on the associated risks and performance of nuclear power. Advanced nuclear reactors have been designed to be simpler and safer, and to have lower costs than currently operating reactor...

  9. High Speed, Low Power Current Comparators with Hysteresis

    Directory of Open Access Journals (Sweden)

    Neeraj K. Chasta

    2012-02-01

    Full Text Available This paper, presents a novel idea for analog current comparison which compares input signal current and reference currents with high speed, low power and well controlled hysteresis. Proposed circuit is based on current mirror and voltage latching techniques which produces rail to rail output voltage as a result of current comparison. The same design can be extended to a simple current comparator without hysteresis (or very less hysteresis, where comparator gives high accuracy (less than 50nA and speed at the cost of moderate power consumption. The comparators are designed optimally and studied at 180 nm CMOS process technology for a supply voltage of 3V.

  10. High Speed, Low Power Current Comparators with Hysteresis

    Directory of Open Access Journals (Sweden)

    Neeraj K. Chasta

    2012-03-01

    Full Text Available This paper, presents a novel idea for analog current comparison which compares input signal current and reference currents with high speed, low power and well controlled hysteresis. Proposed circuit is based on current mirror and voltage latching techniques which produces rail to rail output voltage as a result of current comparison. The same design can be extended to a simple current comparator without hysteresis (or very less hysteresis, where comparator gives high accuracy (less than 50nA and speed at the cost of moderate power consumption. The comparators are designed optimally and studied at 180nm CMOS process technology for a supply voltage of 3V.

  11. High Speed, Low Power Current Comparators with Hysteresis

    CERN Document Server

    Chasta, Neeraj K

    2012-01-01

    This paper, presents a novel idea for analog current comparison which compares input signal current and reference currents with high speed, low power and well controlled hysteresis. Proposed circuit is based on current mirror and voltage latching techniques which produces rail to rail output voltage as a result of current comparison. The same design can be extended to a simple current comparator without hysteresis (or very less hysteresis), where comparator gives high accuracy (less than 50nA) and speed at the cost of moderate power consumption. The comparators are designed optimally and studied at 180nm CMOS process technology for a supply voltage of 3V.

  12. Power electronic converters PWM strategies and current control techniques

    CERN Document Server

    Monmasson, Eric

    2013-01-01

    A voltage converter changes the voltage of an electrical power source and is usually combined with other components to create a power supply. This title is devoted to the control of static converters, which deals with pulse-width modulation (PWM) techniques, and also discusses methods for current control. Various application cases are treated. The book is ideal for professionals in power engineering, power electronics, and electric drives industries, as well as practicing engineers, university professors, postdoctoral fellows, and graduate students.

  13. Unified Power Quality Conditioner for voltage and current compensation

    OpenAIRE

    P.Annapandi; Dr.M.Rajaram

    2012-01-01

    This paper deals with a Unified Power Quality Conditioner (UPQC) for load balancing, power factorcorrection, voltage regulation, voltage and current harmonics mitigation, mitigation of voltage sag, swelland voltage dip in a three-phase three-wire distribution system for different combinations of linear and nonlinear loads.The unified power quality conditioner (UPQC) is a combination of back to back connected shunt and series active power filters (APFs) to a common DC link voltage, which compe...

  14. Assistant solar photovoltaic power supply with AC power grid%太阳能光伏辅助市电供电系统

    Institute of Scientific and Technical Information of China (English)

    欧少敏; 何志毅

    2015-01-01

    By using the solar cell as an assistant power source ,the direct power supply to the electric equipments loaded together by the AC power is achieved without storing battery and input into the power grid .After DC/DC boost ,the photovoltaic output from the solar cells is connected with the output ends of the rectifier bridge ,while tracking the AC power variation to maintain a definite output power under a certain photovoltaic condition .Moreover ,a DC‐DC‐AC inverter is designed to acquire the AC output consistent with AC power in frequency and phase .It output is connected to the electric equipment but separated from the AC power grid by the unidirectional controlling circuit to only load the equipment without inversely flow into the power grid .Thus the high cost of electricity storage ,or power transportation , land occupying ,maintenance as well as technical limitations of grid connection .%以太阳能电池作为辅助电源,实现了与市电共同负载用电设备无蓄电不入网的直接供电方案。将太阳能电池组光伏输出经DC/DC变换器升压后的输出与用电设备的整流桥输出连接,并跟踪市电电压变化使之在相同的光伏条件下维持一定的输出功率;另外也设计了DC/DC/AC变换器电路逆变成与市电同频同相的交流输出,通过单向控制电路与市电隔离,使电源变换电路的输出只加载到用电设备中而不逆流进入到电力网,从而避免高昂的蓄电成本,或并网的输送、占地、维护等成本和入网的技术限制。

  15. A dual mode operated boost inverter and its control strategy for ripple current reduction in single-phase uninterruptible power supplies

    DEFF Research Database (Denmark)

    Tang, Y.; Yao, W.; Blaabjerg, Frede

    2015-01-01

    In single-phase uninterruptible power supply (UPS) applications, it is well known that the AC side instantaneous power is not constant by nature. The resulting input current from the DC source side will inevitably contain low frequency ripple components that may largely deteriorate the system...

  16. AC electrokinetic drug delivery in dentistry using an interdigitated electrode assembly powered by inductive coupling.

    Science.gov (United States)

    Ivanoff, Chris S; Wu, Jie Jayne; Mirzajani, Hadi; Cheng, Cheng; Yuan, Quan; Kevorkyan, Stepan; Gaydarova, Radostina; Tomlekova, Desislava

    2016-10-01

    AC electrokinetics (ACEK) has been shown to deliver certain drugs into human teeth more effectively than diffusion. However, using electrical wires to power intraoral ACEK devices poses risks to patients. The study demonstrates a novel interdigitated electrode arrays (IDE) assembly powered by inductive coupling to induce ACEK effects at appropriate frequencies to motivate drugs wirelessly. A signal generator produces the modulating signal, which multiplies with the carrier signal to produce the amplitude modulated (AM) signal. The AM signal goes through the inductive link to appear on the secondary coil, then rectified and filtered to dispose of its carrier signal, and the positive half of the modulating signal appears on the load. After characterizing the device, the device is validated under light microscopy by motivating carboxylate-modified microspheres, tetracycline, acetaminophen, benzocaine, lidocaine and carbamide peroxide particles with induced ACEK effects. The assembly is finally tested in a common dental bleaching application. After applying 35 % carbamide peroxide to human teeth topically or with the IDE at 1200 Hz, 5 Vpp for 20 min, spectrophotometric analysis showed that compared to diffusion, the IDE enhanced whitening in specular optic and specular optic excluded modes by 215 % and 194 % respectively. Carbamide peroxide absorbance by the ACEK group was two times greater than diffusion as measured by colorimetric oxidation-reduction and UV-Vis spectroscopy at 550 nm. The device motivates drugs of variable molecular weight and structure wirelessly. Wireless transport of drugs to intraoral targets under ACEK effects may potentially improve the efficacy and safety of drug delivery in dentistry.

  17. A Sufficient Condition on Convex Relaxation of AC Optimal Power Flow in Distribution Networks

    DEFF Research Database (Denmark)

    Huang, Shaojun; Wu, Qiuwei; Wang, Jianhui;

    2016-01-01

    solution of the SOCP can be converted to an optimal solution of the original AC OPF. The efficacy of the convex relaxation to solve the AC OPF is demonstrated by case studies of an optimal multi-period planning problem of electric vehicles (EVs) in distribution networks....

  18. Quasienergy spectrum and tunneling current in ac-driven triple quantum dot shuttles

    Energy Technology Data Exchange (ETDEWEB)

    Villavicencio, J [Facultad de Ciencias, Universidad Autonoma de Baja California, Ensenada (Mexico); Maldonado, I [Centro de Investigacion Cientifica y de Educacion Superior de Ensenada (Mexico); Cota, E [Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autonoma de Mexico, Ensenada (Mexico); Platero, G, E-mail: villavics@uabc.edu.mx [Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, 28049 Madrid (Spain)

    2011-02-15

    The dynamics of electrons in ac-driven double quantum dots have been extensively analyzed by means of Floquet theory. In these systems, coherent destruction of tunneling has been shown to occur for certain ac field parameters. In this work we analyze, by means of Floquet theory, the electron dynamics of a triple quantum dot in series attached to electric contacts, where the central dot position oscillates. In particular, we analyze the quasienergy spectrum of this ac-driven nanoelectromechanical system as a function of the intensity and frequency of the ac field and of external dc voltages. For strong driving fields, we derive, by means of perturbation theory, analytical expressions for the quasienergies of the driven oscillator system. From this analysis, we discuss the conditions for coherent destruction of tunneling (CDT) to occur as a function of detuning and field parameters. For zero detuning, and from the invariance of the Floquet Hamiltonian under a generalized parity transformation, we find analytical expressions describing the symmetry properties of the Fourier components of the Floquet states under such a transformation. By using these expressions, we show that in the vicinity of the CDT condition, the quasienergy spectrum exhibits exact crossings which can be characterized by the parity properties of the corresponding eigenvectors.

  19. Measurement of AC transport current losses in YBCO coated conductor%高温超导YBCO带材的交流传输电流损耗测量

    Institute of Scientific and Technical Information of China (English)

    李晓群; 何清; 金涛; 周世平; 李敬东; 任丽; 唐跃进

    2012-01-01

    In this paper, the AC transport current losses of YBCO coated conductor was studied under different currents and different frequencies respectively. The YBCO tape used in this experiment was SCS4050 produced by Superpower Inc. , which was measured in liquid nitrogen (77 K) by a sensitive electrical method with a lock -in amplifier. The measured AC transport current losses results were compared with the Norris formula calculative results when the power frequency equaled to 50 Hz. The measured results in different frequencies which varied from 15Hz to 300Hz were also provided.%文中对不同频率不同幅值的交变电流下高温超导体YBCO带材的交流传输损耗进行了实验研究.实验在77K下,对Superpower公司生产的SCS4050型号带材采用电测法通过锁相放大器进行了交流损耗值的测量,并将其工作电流为50Hz时的测量结果与Norris矩形模型估算值进行了对比,同时也给出了15Hz到300Hz不同频率下交流损耗测量结果的比较分析.

  20. Development of Harmonic-Noise Reduction Technology in Diagnostic Method using AC Loss Current for Water Treed XLPE Cable

    Science.gov (United States)

    Tsujimoto, Tomiyuki; Nakade, Masahiko; Yagi, Yukihiro; Ishii, Noboru

    Water tree is one of the degradation aspects of XLPE cables used for under-ground distribution or transmission lines. We have developed the loss current method using 3rd harmonic in AC loss current for cable diagnosis. Harmonic components in loss current arise as a result of the non-linear voltage-current characteristics of water trees. We confirmed that the 3rd harmonic in AC loss current had good correlation with water tree growth and break down strength. After that, we have applied this method to the actual 66kV XLPE cable lines. Up to now, the number of the application results is more than 120 lines. In this method, it is sometimes said that the degradation signal (3rd harmonic in loss current) is affected by the 3rd harmonic in the test voltage. To indicate and solve this problem, we investigated the extent of influence by 3rd harmonic in the test voltage, and found the rule of the influence. As a result, we developed a new technique of harmonic-noise reduction in loss current method that enabled a more highly accurate diagnosis and confirmed the effectiveness of this new technique by simulations and experiments with actual cables.

  1. Oxycoal-AC. Innovative components and concepts for the power plants of the future

    Energy Technology Data Exchange (ETDEWEB)

    Kneer, Reinhold; Toporov, Dobrin; Foerster, Malte [RWTH Aachen Univ. (DE). Inst. of Heat and Mass transfer (WSA)

    2010-07-01

    In the framework of the OXYCOAL-AC research project, detailed experimental and numerical investigations of oxycoal swirl flames have been made. The effects of high CO{sub 2} concentrations in the gas mixture during oxy-firing on the volatiles and particle ignition, flame propagation, flame stability, emissions and heat transfer in the boiler have been investigated and analyzed. Measures for oxy-flame stabilization as a function of flue gas recycling ratio (02 content) are derived and a swirl burner able to operate in both air and oxy-firing has been developed. Thus, OXYCOAL-AC became the first test-plant worldwide where coal can be burnt in a stable flame in a CO{sub 2} atmosphere with oxygen content between 18 and 30 vol. %. In addition, the development of the key component in the OXYCOAL-AC process, an ion transport membrane for oxigen production, is ongoing. Appropriate membrane materials have been identified and tested for their applicability to oxycoal conditions. Laboratory scale modules have been designed and successfully operated as membrane-based air separation units. Design concepts of scaled up membrane modules and their integration in pilot or power plant scale facilities are under development. Fly ash separation from the recycled hot flue gas is investigated by testing different ceramic filter materials. First oxy-firing experiments with wet recycled flue gas have shown an increased slagging behaviour of fly ash compared to air-firing conditions. Therefore more investigations on the behaviour of coal ash in oxyfuel atmosphere are scheduled. Further, numerical simulations of a utility scale (1200 MW{sub th}) boiler oxy-firing bituminous coal, based on non-grey implementation of the Exponential Wide Band Model, were performed with respect to retrofit. Comparisons are made between air firing and oxy-firing under boundary conditions varying with respect to oxygen and water content of the oxidizer. Predictions have shown that a significant increase of the

  2. Measurement of H!gh Power Current-Stabilized Power Supply with High Stability

    Institute of Scientific and Technical Information of China (English)

    YanHuaihai; FengXiuming; BaiZhen; ZhouZhongzu

    2003-01-01

    The DC power supply system of HIRFL has been upgraded since 1999, these new power supplies are used mainly as high frequency ZVS soft-switching converters or thyristor phase-controlled rectifiers. Each power supply is strictly tested before being put into operation, especially for long-term current stability, current ripple, efficiency, repeatability, EMI and so on. The tested results indicated that performances of power supplies satisfy requirement of HIRFL.

  3. 基于AC/DC数字电源控制器IW1810的LED驱动电路设计%Based on the AC/DC Digital Power Supply Controller IW1810 LED Driver Design

    Institute of Scientific and Technical Information of China (English)

    徐晶; 付贤松; 牛萍娟

    2014-01-01

    The IW1810 incorporates a 64 kHz controller and a 800 V BJT. The device uses the numerical control technology and operates in quasi-resonant mode to provide current and output overvoltage protection, while minimizing the external component count and ensuring the high efficiency, no load power is less than 100 mW. Based on IW1810 designed a highly integrated,high efficient and constant current AC/DC LED driver circuit was designed. The circuit operates at 90 V to 264 V wide voltage range,output current is 340 mA,output power is 4 W, efficiency up to 80%,the area of the designed source is only 18 mm×38 mm.%IW1810集成了一个64 kHz的PWM控制器和一个800 V的BJT,该芯片采用数控技术,工作在准谐振模式,提供过流和输出过压保护,简化外围元件确保电路的高效性,无载功率小于100 mW。设计一款基于IW1810高度集成、高效恒流的AC/DC LED驱动电路,电路工作在90 V到264 V的宽电压范围内,输出恒流340 mA,输出功率为4 W,效率高达80%以上,电路板面积仅为18 mm×38 mm。

  4. Effective variable switching point predictive current control for ac low-voltage drives

    Science.gov (United States)

    Stolze, Peter; Karamanakos, Petros; Kennel, Ralph; Manias, Stefanos; Endisch, Christian

    2015-07-01

    This paper presents an effective model predictive current control scheme for induction machines driven by a three-level neutral point clamped inverter, called variable switching point predictive current control. Despite the fact that direct, enumeration-based model predictive control (MPC) strategies are very popular in the field of power electronics due to their numerous advantages such as design simplicity and straightforward implementation procedure, they carry two major drawbacks. These are the increased computational effort and the high ripples on the controlled variables, resulting in a limited applicability of such methods. The high ripples occur because in direct MPC algorithms the actuating variable can only be changed at the beginning of a sampling interval. A possible remedy for this would be to change the applied control input within the sampling interval, and thus to apply it for a shorter time than one sample. However, since such a solution would lead to an additional overhead which is crucial especially for multilevel inverters, a heuristic preselection of the optimal control action is adopted to keep the computational complexity at bay. Experimental results are provided to verify the potential advantages of the proposed strategy.

  5. Unified Power Quality Conditioner for voltage and current compensation

    Directory of Open Access Journals (Sweden)

    P.Annapandi

    2012-07-01

    Full Text Available This paper deals with a Unified Power Quality Conditioner (UPQC for load balancing, power factorcorrection, voltage regulation, voltage and current harmonics mitigation, mitigation of voltage sag, swelland voltage dip in a three-phase three-wire distribution system for different combinations of linear and nonlinear loads.The unified power quality conditioner (UPQC is a combination of back to back connected shunt and series active power filters (APFs to a common DC link voltage, which compensates voltage and current based distortions, independently.Using instantaneous active and reactive Power theory ,harmonic detection, reactive power compensation, voltage sag and swell have been simulated and the results are analyzed. The operation and capability of the proposed system was analyzed through simulations with MATLAB / SIMULINK.

  6. Current distribution mapping in insulated (Gd,Y)BCO based stabilizer-free coated conductor after AC over-current test for R-SFCL application

    Science.gov (United States)

    Kar, Soumen; Li, Xiao-Fen; Selvamanickam, Venkat; Rao, V. V.

    2017-02-01

    Uniformity of critical current (Ic ) over long lengths of (GdY)-Ba-Cu-O ((Gd,Y)BCO)-based high temperature superconducting (HTS) tapes after long periods of AC current excitation is an important criterion in their selection for resistive type superconducting fault current limiter (R-SFCL). The present work describes such critical current (Ic ) uniformity measurements performed over 1m long, stabilizer-free (SF), 12 mm wide, 2nd generation (2G) (Gd,Y)BCO based HTS tape. A non-destructive method using a static hall probe (Tapestar®) with moving HTS tape configuration was employed for estimation of Ic uniformity. Scanning Hall probe microscopy (SHPM) was then used to examine the weak superconducting regions (i.e. less Ic ) with a static HTS tape. Remanent field distribution on the HTS tape was measured to yield the critical current density distribution. Except for small degradation of Ic at some locations, these studies confirmed near-uniform critical current distribution over meter-long (Gd,Y)BCO tapes, both in virgin state and after exposure to AC over current.

  7. Fast Decoupled Power Flow for Power System with High Voltage Direct Current Transmission Line System

    Directory of Open Access Journals (Sweden)

    Prechanon Kumkratug

    2010-01-01

    Full Text Available Problem statement: High voltage direct current transmission line system has been widely applied for control power flow in power system. The power flow analysis was the one of powerful tools by which the power system equipped was analyzed both for planning and operation strategies. Approach: This study presented the method to analyze power flow of power system consisted of HVDC system. HVDC was modeled as the complex power injections. The presented complex power injected was incorporated into the existing power flow program based on fast decoupled method. The presented method was tested on the multimachine power system. Results: The transmission line loss of the system with and without HVDC was compared. Conclusion: From the simulation results, the HVDC can reduce transmission line loss of power system.

  8. Blackout Accdent Analyses of AC 600 Nuclear Power Plant%AC600核电厂新电事故分析

    Institute of Scientific and Technical Information of China (English)

    阎义洲; 臧希年

    2002-01-01

    In the advanced pressurized water reactor nuclear power plant design, the passive residual heat removal system is adopted. This system is composed of the secondary side of steam generator, air cooler and air loop which consists of the air cooling tower and atmosphere environment. Wall-air heat exchanging correlation equation is added to the RELAP5 Code. The modified code is used to simulate the AC600 PWR nuclear power plant transient behavior with Passive Residual Heat Removal System (PRHR) in micro-circulation start-up mode after the blackout accident occurs.The calculation results show that the higher the chimney or the larger the air cooler heat transfer area, the more the heat removal capacity of PRHR system. The computational results are consistent with the theoretical analyses.%我国改进型压水堆核电站设计中采用了非能动余热排出系统,它由蒸汽发生器及空气冷却器构成的汽水回路和空气回路组成.本文在RELAP5程序中补充了空气壁面换热结构关系式,分析改进型压水堆核电站(AC600)全厂断电事故后的瞬态行为.结果表明:烟囱高度增加、换热面积增加均使系统的排热能力增强;计算结果与理论分析结果相一致.

  9. A combined noise analysis and power supply current based testing of CMOS analog integrated circuits

    Science.gov (United States)

    Srivastava, Ashok; Pulendra, Vani K.; Yellampalli, Siva

    2005-05-01

    A technique integrating the noise analysis based testing and the conventional power supply current testing of CMOS analog integrated circuits is presented for bridging type faults due to manufacturing defects. The circuit under test (CUT) is a CMOS amplifier designed for operation at +/- 2.5 V and implemented in 1.5 μm CMOS process. The faults simulating possible manufacturing defects have been introduced using the fault injection transistors. The amplifier circuit is analyzed and simulated in SPICE for its performance with and without fault injections. The faults in the CUT are identified by observing the variation in the equivalent noise voltage at the output of CUT. In power supply current testing, the current (IPS) through the power supply voltage, VDD is measured under the application of an AC input stimulus. The effect of parametric variation is taken into consideration by determining the tolerance limit using the Monte-Carlo analysis. The fault is identified if the power supply current, IPS lies outside the deviation given by Monte-Carlo analysis. Simulation results are in close agreement with the corresponding experimental values.

  10. Unity power factor converter

    Science.gov (United States)

    Wester, Gene W. (Inventor)

    1980-01-01

    A unity power factor converter capable of effecting either inversion (dc-to-dc) or rectification (ac-to-dc), and capable of providing bilateral power control from a DC source (or load) through an AC transmission line to a DC load (or source) for power flow in either direction, is comprised of comparators for comparing the AC current i with an AC signal i.sub.ref (or its phase inversion) derived from the AC ports to generate control signals to operate a switch control circuit for high speed switching to shape the AC current waveform to a sine waveform, and synchronize it in phase and frequency with the AC voltage at the AC ports, by selectively switching the connections to a series inductor as required to increase or decrease the current i.

  11. Low profile, highly configurable, current sharing paralleled wide band gap power device power module

    Science.gov (United States)

    McPherson, Brice; Killeen, Peter D.; Lostetter, Alex; Shaw, Robert; Passmore, Brandon; Hornberger, Jared; Berry, Tony M

    2016-08-23

    A power module with multiple equalized parallel power paths supporting multiple parallel bare die power devices constructed with low inductance equalized current paths for even current sharing and clean switching events. Wide low profile power contacts provide low inductance, short current paths, and large conductor cross section area provides for massive current carrying. An internal gate & source kelvin interconnection substrate is provided with individual ballast resistors and simple bolted construction. Gate drive connectors are provided on either left or right size of the module. The module is configurable as half bridge, full bridge, common source, and common drain topologies.

  12. OXYCOAL-AC: Towards an integrated coal-fired power plant process with ion transport membrane-based oxygen supply

    Energy Technology Data Exchange (ETDEWEB)

    Kneer, R.; Toporov, D.; Forster, M.; Christ, D.; Broeckmann, C.; Pfaff, E.; Zwick, M.; Engels, S.; Modigell, M. [Rhein Westfal TH Aachen, Aachen (Germany). Inst. of Heat & Mass Transfer

    2010-07-01

    The cooperative project OXYCOAL-AC aims at the development of a zero-CO{sub 2}-emission coal combustion process for power generation. The scope of the research comprises a multitude of aspects. This article focuses on membrane-based air separation modules and their design for oxycoal conditions, the specifics of coal combustion in a CO{sub 2}/O{sub 2} atmosphere including related burner design as well as the cleaning of hot flue gas from oxycoal combustion.

  13. Investigation of the effects of transcranial alternating current stimulation (tACS) on self-paced rhythmic movements.

    Science.gov (United States)

    Varlet, Manuel; Wade, Alanna; Novembre, Giacomo; Keller, Peter E

    2017-03-18

    Human rhythmic movements spontaneously entrain to external rhythmic stimuli. Such sensory-motor entrainment can attract movements to different tempi and enhance their efficiency, with potential clinical applications for motor rehabilitation. Here we investigate whether entrainment of self-paced rhythmic movements can be induced via transcranial alternating current stimulation (tACS), which uses alternating currents to entrain spontaneous brain oscillations at specific frequencies. Participants swung a handheld pendulum at their preferred tempo with the right hand while tACS was applied over their left or right primary motor cortex at frequencies equal to their preferred tempo (Experiment 1) or in the alpha (10Hz) and beta (20Hz) ranges (Experiment 2). Given that entrainment generally occurs only if the frequency difference between two rhythms is small, stimulations were delivered at frequencies equal to participants' preferred movement tempo (≈1Hz) and ±12.5% in Experiment 1, and at 10Hz and 20Hz, and ±12.5% in Experiment 2. The comparison of participants' movement frequency, amplitude, variability, and phase synchrony with and without tACS failed to reveal entrainment or movement modifications across the two experiments. However, significant differences in stimulation-related side effects reported by participants were found between the two experiments, with phosphenes and burning sensations principally occurring in Experiment 2, and metallic tastes reported marginally more often in Experiment 1. Although other stimulation protocols may be effective, our results suggest that rhythmic movements such as pendulum swinging or locomotion that are low in goal-directedness and/or strongly driven by peripheral and mechanical constraints may not be susceptible to modulation by tACS.

  14. Soft switching (ZVZCS) high current, low voltage modular power converter (13 kA, 16 V)

    CERN Document Server

    Bordry, Frederick; Thiesen, H

    2001-01-01

    The Large Hadron Collider (LHC) is the next accelerator being constructed at the European Laboratory for Particle Physics (CERN). The superconducting LHC particle accelerator requires high currents (13 kA) and relatively low voltages (16 V) for its magnets. This paper describes the development and the production of a (13 kA, 16 V) power converter. The converter is made with a modular concept with five current sources (3.25 kA, 16 V) in parallel. The 3.25 kA sources are built as plug-in modules: a diode rectifier on the AC mains, a zero voltage zero current switching (ZVZCS) inverter working at 25 k Hz and an output stage. The obtained performance is presented and discussed. (6 refs).

  15. Current control for a shunt hybrid active power filter using recursive integral PI

    Institute of Scientific and Technical Information of China (English)

    Wei ZHAO; An LUO; Ke PENG; Xia DENG

    2009-01-01

    This paper presents a current control method for a shunt hybrid active power filter(HAPF) using recursive integral Pl algorithm.The method improves the performance of the HAPF system by reducing the influence of detection accuracy,time delay of instruction current calculation and phase displacement of output filter.Fuzzy logic based set-point weighing algorithm is combined in the control scheme to enhance its robustness and anti-interference ability.The proposed algorithm is easy to implement for engineering applications and easy to compute.Experiment results have verified the validity of the proposed controller.Furthermore,the proposed recursive integral PI algorithm can also be applied in the control of periodic current as in AC drivers.

  16. Current Advanced Power Generation Technologies and Options for China (1)

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ In China,electricity consumption keeps growing at a high speed and installed capacity will be doubled in the next fifteen years.As the world second CO2 producer and also a member of Kyoto Protocol,how to balance energy needs and environmental protection responsibility in the future is a serious problem for China.As such,there are a number of technology choices for today's electric power generation.After discussing the current advanced power generation technologies based on Chinese energy structure and current conditions of power industry,this paper gives a reference to the technology options for China in the future.

  17. Evaluation of Current Controllers for Distributed Power Generation Systems

    DEFF Research Database (Denmark)

    Timbus, Adrian; Liserre, Marco; Teodorescu, Remus

    2009-01-01

    This paper discusses the evaluation of different current controllers employed for grid-connected distributed power generation systems having variable input power, such as wind turbines and photovoltaic systems. The focus is mainly set on linear controllers such as proportional....... First, in steady-state conditions, the contribution of controllers to the total harmonic distortion of the grid current is pursued. Further on, the behavior of controllers in the case of transient conditions like input power variations and grid voltage faults is also examined. Experimental results...

  18. Active current control in wind power plants during grid faults

    DEFF Research Database (Denmark)

    Martinez, Jorge; Kjær, Phillip C.; Rodriguez, Pedro

    2010-01-01

    , wind turbines usually have solutions that enable the turbines to control the generation of reactive power during faults. This paper addresses the importance of using an optimal injection of active current during faults in order to fulfil these grid codes. This is of relevant importance for severe......Modern wind power plants are required and designed to ride through faults in electrical networks, subject to fault clearing. Wind turbine fault current contribution is required from most countries with a high amount of wind power penetration. In order to comply with such grid code requirements...

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

    Science.gov (United States)

    2010-06-01

    Tach Tach K8061 USB Board DC 1 Power Supply Wall Outlet Power Supply Zach’s FPGA Board Computer Cycle Counter OpAmp B o ard DC 2...the Frequency (Counter) Opamp circuit card iv. Connect the 5v and ±12 Volts commons f. Verify power supply two (PS2), I used the White power...to Cooling Fans 131 The Circuit Board Architectures USB Board Schematic 132 Zach’s FPGA Board 133 Rachel’s OpAmp /Cycle

  20. Analytical Solution for Model-Based Dynamic Power Factor Measurement in AC Resistance Spot Welding

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    On the basis of welding transformer circuit model, a new measuring method was proposed. This method measures the peak angle of the welding current, and then calculates the dynamic power factor in each half-wave.An artificial neural network is trained and used to generate simulation data for the analytical solution, i.e. a highorder binary polynomial, which can be easily adopted to calculate the power factor online. The tailored sensing and computing system ensures that the method possesses a real-time computational capacity and satisfying accuracy. A DSP-based resistance spot welding monitoring system was developed to perform ANN computation. The experimental results suggest that this measuring method is feasible.

  1. Anomalous Power Law Dispersions in ac Conductivity and Permittivity Shown to be Characteristics of Microstructural Electrical Networks

    Science.gov (United States)

    Almond, D. P.; Bowen, C. R.

    2004-04-01

    The frequency dependent ac conductivity and permittivity of porous lead zirconate titanate ceramic with the pore volume filled with water are shown to match the simulated electrical response of a large network of randomly positioned resistors and capacitors. Anomalous power law dispersions in conductivity and permittivity are shown to be an electrical response characteristic of the microstructural network formed by the porous lead zirconate titanate pore structure. The anomalous power law dispersions of a wide range of materials are also suggested to be microstructural network characteristics.

  2. Impact of Negative Sequence Current Injection by Wind Power Plants

    DEFF Research Database (Denmark)

    Chaudhary, Sanjay; Göksu, Ömer; Teodorescu, Remus;

    2013-01-01

    This paper presents an analysis of the impact from negative sequence current injection by wind power plants in power systems under steady-state and short-term unbalanced conditions, including faults. The separate positive and negative sequence current control capability of the grid-side converters...... of full scale converter type wind turbines may be utilized to alter voltage imbalance at the point of connection and further into the grid, in turn changing the resultant negative sequence current flow in the grid. The effects of such control actions have been analyzed and discussed through theoretical...

  3. Current-Driven Switch-Mode Audio Power Amplifiers

    DEFF Research Database (Denmark)

    Knott, Arnold; Buhl, Niels Christian; Andersen, Michael A. E.

    2012-01-01

    The conversion of electrical energy into sound waves by electromechanical transducers is proportional to the current through the coil of the transducer. However virtually all audio power amplifiers provide a controlled voltage through the interface to the transducer. This paper is presenting...... a switch-mode audio power amplifier not only providing controlled current but also being supplied by current. This results in an output filter size reduction by a factor of 6. The implemented prototype shows decent audio performance with THD + N below 0.1 %....

  4. Directed Current Induced by an Symmetrically ac Force Coexisting with a Time-Delayed Feedback

    Institute of Scientific and Technical Information of China (English)

    易述婷; 宋晖; 欧志娥; 艾保全; 熊建文

    2012-01-01

    We study the transport of overdamped Brownian particles in a symmetricaJly periodic potential in the presence of an asymmetrically ac driving force and a time-delayed feedback. It is found that for low frequencies, the average velocity can be negative by changing the driving amplitude, for high frequencies, there exists an optimized driving amplitude at which the average velocity takes its maximum value. Additionally, there is a threshold value of driving amplitude below which no directed transport can be obtained for high frequencies. For the large value of the delay time, the average velocity is independent of the delay time.

  5. Optimal Selection of Floating Platform for Tidal Current Power Station

    Directory of Open Access Journals (Sweden)

    Fengmei Jing

    2013-06-01

    Full Text Available With continuous development of marine engineering, more and more new structures are used in the exploring of tidal current energy. Three are there different kinds of support structures for tidal current power station, which are sea-bed mounted/gravity based system, pile mounted system and floating moored platform. Comparison with them, the floating mooring system is suit for deep water and the application of which will be widely. In this study, catamaran and semi-submersible as floating platform of tidal current power station are studied. And they are compared with its economic, efficiency of turbine and stability of station. It is found that the catamaran is optimal choice. Based on basic ship theory and using software MOSES, the stability of Catamaran tidal current power station is also calculated. The research of this study is significant and it will be as the reference for the future study.

  6. Finite element model predicts current density distribution for clinical applications of tDCS and tACS

    Directory of Open Access Journals (Sweden)

    Toralf eNeuling

    2012-09-01

    Full Text Available Transcranial direct current stimulation (tDCS has been applied in numerous scientific studies over the past decade. However, the possibility to apply tDCS in therapy of neuropsychiatric disorders is still debated. While transcranial magnetic stimulation (TMS has been approved for treatment of major depression in the United States by the Food and Drug Administration (FDA, tDCS is not as widely accepted. One of the criticisms against tDCS is the lack of spatial specificity. Focality is limited by the electrode size (35 cm2 are commonly used and the bipolar arrangement. However, a current flow through the head directly from anode to cathode is an outdated view. Finite element (FE models have recently been used to predict the exact current flow during tDCS. These simulations have demonstrated that the current flow depends on tissue shape and conductivity. Toface the challenge to predict the location, magnitude and direction of the current flow induced by tDCS and transcranial alternating current stimulation (tACS, we used a refined realistic FE modeling approach. With respect to the literature on clinical tDCS and tACS, we analyzed two common setups for the location of the stimulation electrodes which target the frontal lobe and the occipital lobe, respectively. We compared lateral and medial electrode configuration with regard to theirusability. We were able to demonstrate that the lateral configurations yielded more focused stimulation areas as well as higher current intensities in the target areas. The high resolution of our simulation allows one to combine the modeled current flow with the knowledge of neuronal orientation to predict the consequences of tDCS and tACS. Our results not only offer a basis for a deeper understanding of the stimulation sites currently in use for clinical applications but also offer a better interpretation of observed effects.

  7. Power sharing algorithm for vector controlled six-phase AC motor with four customary three-phase voltage source inverter drive

    Directory of Open Access Journals (Sweden)

    Sanjeevikumar Padmanaban

    2015-09-01

    Full Text Available This paper considered a six-phase (asymmetrical induction motor, kept 30° phase displacement between two set of three-phase open-end stator windings configuration. The drive system consists of four classical three-phase voltage inverters (VSIs and all four dc sources are deliberately kept isolated. Therefore, zero-sequence/homopolar current components cannot flow. The original and effective power sharing algorithm is proposed in this paper with three variables (degree of freedom based on synchronous field oriented control (FOC. A standard three-level space vector pulse width modulation (SVPWM by nearest three vectors (NTVs approach is adopted to regulate each couple of VSIs. The proposed power sharing algorithm is verified by complete numerical simulation modeling (Matlab/Simulink-PLECS software of whole ac drive system by observing the dynamic behaviors in different designed condition. Set of results are provided in this paper, which confirms a good agreement with theoretical development.

  8. Enhancement of Power Quality in Transmission Line Using Flexible Ac Transmission System Device U.P.F.C (Unified Power Flow Controller

    Directory of Open Access Journals (Sweden)

    B. Divya Lakshmi

    2014-04-01

    Full Text Available Present scenario states that power demand has been increased in a rapid and random manner. Hence power generated is unable to meet the power demand so power scarcity exists. There is an approximate loss of (20 - 40 % of power generated during its transmission. Hence there is a need for enhancing the power quality in transmission lines. In order to improve the power quality our paper make use of FACTS DEVICES. FACTS devices can be added to power transmission and distribution systems at appropriate locations to improve system performance. The real and reactive powers can be easily controlled in a power system with FACTS devices. Flexible AC Transmission System creates a tremendous quality impact on power system stability. This paper describes the basic principle of operation of UPFC, its advantages and to compare its performance with the various FACTS equipment available. The objective of this paper is to keep the power system to remain in voltage stable condition when it experiences a load change and contingency, also deals with the simulation of various FACTS controllers using simulation program with MATLAB/SIMULINK

  9. Estimation of coefficients of multivariable power series approximating magnetic nonlinearity of AC machines*

    Directory of Open Access Journals (Sweden)

    Sobczyk Tadeusz J.

    2015-09-01

    Full Text Available Energy based approach was used in the study to formulate a set of functions approximating the magnetic flux linkages versus independent currents. The simplest power series that approximates field co-energy and linked fluxes for a two winding core of an induction machine are described by a set of common unknown coefficients. The authors tested three algorithms for the coefficient estimation using Weighted Least-Squared Method for two different positions of the coils. The comparison of the approximation accuracy was accomplished in the specified area of the currents. All proposed algorithms of the coefficient estimation have been found to be effective. The algorithm based solely on the magnetic field co-energy values is significantly simpler than the method based on the magnetic flux linkages estimation concept. The algorithm based on the field co-energy and linked fluxes seems to be the most suitable for determining simultaneously the coefficients of power series approximating linked fluxes and field co-energy.

  10. AC current driven dynamic vortex state in YBa{sub 2}Cu{sub 3}O{sub 7-x}

    Energy Technology Data Exchange (ETDEWEB)

    Lucarelli, A.; Frey, A.; Yang, R.; Luepke, G. [The College of William and Mary, Department of Applied Science, Williamsburg, VA (United States); Grilli, F. [Los Alamos National Laboratory, Superconductivity Technology Center, Los Alamos, NM (United States); Haugan, T.; Levin, G.; Barnes, P. [Air Force Research Laboratory, Wright-Patterson AFB, OH (United States)

    2007-09-15

    Time-resolved magneto-optical imaging measurements show that an ac current enables the vortex matter in YBa{sub 2}Cu{sub 3}O{sub 7-x} thin films to reorganize into two coexisting steady states of driven vortex motion with different characteristics: a quasi-static disordered glassy state in the sample interior and a dynamic state of plastic motion near the edges. Finite-element calculations consistent with the critical state model show good agreement with the measured field profiles in the quasi-static state but predict a larger hysteretic behavior in the dynamic state. (orig.)

  11. Mini Solar and Sea Current Power Generation System

    Science.gov (United States)

    Almenhali, Abdulrahman; Alshamsi, Hatem; Aljunaibi, Yaser; Almussabi, Dheyab; Alshehhi, Ahmed; Hilal, Hassan Bu

    2017-07-01

    The power demand in United Arab Emirates is increased so that there is a consistent power cut in our region. This is because of high power consumption by factories and also due to less availability of conventional energy resources. Electricity is most needed facility for the human being. All the conventional energy resources are depleting day by day. So we have to shift from conventional to non-conventional energy resources. In this the combination of two energy resources is takes place i.e. wind and solar energy. This process reviles the sustainable energy resources without damaging the nature. We can give uninterrupted power by using hybrid energy system. Basically this system involves the integration of two energy system that will give continuous power. Solar panels are used for converting solar energy and wind turbines are used for converting wind energy into electricity. This electrical power can utilize for various purpose. Generation of electricity will be takes place at affordable cost. This paper deals with the generation of electricity by using two sources combine which leads to generate electricity with affordable cost without damaging the nature balance. The purpose of this project was to design a portable and low cost power system that combines both sea current electric turbine and solar electric technologies. This system will be designed in efforts to develop a power solution for remote locations or use it as another source of green power.

  12. Methodology for simulation of geomagnetically induced currents in power systems

    Directory of Open Access Journals (Sweden)

    Boteler David

    2014-07-01

    Full Text Available To assess the geomagnetic hazard to power systems it is useful to be able to simulate the geomagnetically induced currents (GIC that are produced during major geomagnetic disturbances. This paper examines the methodology used in power system analysis and shows how it can be applied to modelling GIC. Electric fields in the area of the power network are used to determine the voltage sources or equivalent current sources in the transmission lines. The power network can be described by a mesh impedance matrix which is combined with the voltage sources to calculate the GIC in each loop. Alternatively the power network can be described by a nodal admittance matrix which is combined with the sum of current sources into each node to calculate the nodal voltages which are then used to calculate the GIC in the transmission lines and GIC flowing to ground at each substation. Practical calculations can be made by superposition of results calculated separately for northward and eastward electric fields. This can be done using magnetic data from a single observatory to calculate an electric field that is a uniform approximation of the field over the area of the power system. It is also shown how the superposition of results can be extended to use data from two observatories: approximating the electric field by a linear variation between the two observatory locations. These calculations provide an efficient method for simulating the GIC that would be produced by historically significant geomagnetic storm events.

  13. High voltage direct current modelling in optimal power flows

    Energy Technology Data Exchange (ETDEWEB)

    Ambriz-Perez, H. [Comision Federal de Electricidad, Mexico, Unidad de Ingenieria Especializada, Rio Rodano No. 14 - Piso 10, Sala 1002, Col. Cuauhtemoc, C.P. 06598, Mexico, D.F. (Mexico); Acha, E. [Department of Electronics and Electrical Engineering, University of Glasgow, Glasgow G128LT, Scotland (United Kingdom); Fuerte-Esquivel, C.R. [Faculty of Electrical Engineering, Universidad Michoacana de San Nicolas de Hidalgo, Morelia 58030, Michoacan (Mexico)

    2008-03-15

    Two-terminal high voltage direct current (HVDC) transmission links are in operation throughout the world. They are key elements in electrical power networks; their representation is oversimplified or ignored in most power system studies. This is particularly the case in Optima Power Flow (OPF) studies. Hence, an OPF program has been extended to incorporate HVDC links, taking due account of overlapping and power transfer control characteristics. This is a new development in Newton Optimal Power Flows, where the converter equations are included directly in the matrix W. The method is indeed a unified one since the solution vector is extended to accommodate the DC variables. The HVDC link model correctly takes into account the relevant DC limit variables. The impact of HVDC links on OPF studies is illustrated by numeric examples, which includes a 5-node system, the AEP 14-node and a 166-node system. (author)

  14. Transient Power Converse in an AC/DC Interconnected Power Grid%交直流电网故障暂态功率倒向解析

    Institute of Scientific and Technical Information of China (English)

    李晓华; 蔡泽祥; 黄明辉; 刘之尧; 李一泉

    2012-01-01

    针对交直流电网出现的暂态功率倒向现象而导致继电保护误动的问题,从继电保护的视角出发,在电磁暂态时间框架下研究交直流系统相互影响机理和交流故障特征的变异机理,提出在换相失败电磁暂态过程的解析分析、特征变异对保护性能的影响评估方法和评价指标,进而给出了交直流混合电网界定暂态功率倒向的计算模型和方法。交直流系统相互作用而引发的暂态功率倒向是由交流故障和直流系统快速变化引起的2个不同扰动源同时作用于电网元件,且满足一定电气和时序条件下“竞争”的必然结果。仿真结果验证了所述模型和方法的正确性。%In view of the transient power converse leading to the malfunction of the protective relay the AC/DC power grid, the mechanism of interaction of AC/DC systems and the change of AC fault features are studied in the electromagnetic transient time framework from the viewpoint of protective relaying. The HVDC commutation failure is analyzed. The evaluation method for and indices on the influence of the resolving analysis and fault feature variation on the protection performance are proposed in the electromagnetic transient process of commutation failure. Then the method of calculating the boundary of the transient power converse is presented. The transient power converse occurring in the AC/DC power grid is an inevitable result of electric competition and time sequence competition between the disturbance due to AC fault and that due to the rapid response of HVDC. Simulation results show the validity of the model and method proposed.

  15. A new high-performance AC/DC power factor correction switching converter based on one-cycle control technology and active floating-charge technology

    Institute of Scientific and Technical Information of China (English)

    GAO Chao

    2008-01-01

    A new family of converters, high-performance AC/DC power factor correction (PFC) switching converters with one-cycle control technology and active floating-charge technology, was derived and experimentally verified. The topology of a single-phase CCM and DCM Boost-PFC switching converter was also analyzed. Its operating prniciples and control methods were expounded. Based on these, a new type of AC/DC switching converter circuits for PFC combined with one-cycle control technology was presented herein. The proposed AC/DC switching converter significantly helps improve the converter efficiency and its power factor value.

  16. Low-Voltage Ultra-Low-Power Current Conveyor Based on Quasi-Floating Gate Transistors

    Directory of Open Access Journals (Sweden)

    F. Khateb

    2012-06-01

    Full Text Available The field of low-voltage low-power CMOS technology has grown rapidly in recent years; it is an essential prerequisite particularly for portable electronic equipment and implantable medical devices due to its influence on battery lifetime. Recently, significant improvements in implementing circuits working in the low-voltage low-power area have been achieved, but circuit designers face severe challenges when trying to improve or even maintain the circuit performance with reduced supply voltage. In this paper, a low-voltage ultra-low-power current conveyor second generation CCII based on quasi-floating gate transistors is presented. The proposed circuit operates at a very low supply voltage of only ±0.4 V with rail-to-rail voltage swing capability and a total quiescent power consumption of mere 9.5 µW. Further, the proposed circuit is not only able to process the AC signal as it's usual at quasi-floating gate transistors but also the DC which extends the applicability of the proposed circuit. In conclusion, an application example of the current-mode quadrature oscillator is presented. PSpice simulation results using the 0.18 µm TSMC CMOS technology are included to confirm the attractive properties of the proposed circuit.

  17. High Current, Low Voltage Power Converter [20kA, 6V] LHC Converter Prototype

    CERN Document Server

    Jørgensen, H E; Dupaquier, A; Fernqvist, G

    1998-01-01

    The superconducting LHC accelerator requires high currents (~12.5kA) and relatively low voltages (~10 V) for its magnets. The need to install the power converters underground is the driving force for reduced volume and high efficiency. Moreover, the LHC machine will require a very high level of performance from the power converters, particularly in terms of DC stability, dynamic response and also in matters of EMC. To meet these requirements soft-switching techniques will be used. This paper describes the development of a [20kA,6V] power converter intended as a stable high-current source for D CCT calibration and an evaluation prototype for the future LHC converters. The converter is made with a modular concept with five current sources [4kA,6V] in parallel. The 4kA sources are built as plu g-in modules: a diode rectifier on the AC mains with a damped L-C passive filter, a Zero Voltage Switching inverter working at 20 kHz and an output stage (high frequency transformers, Schottky rectifi ers and output filter...

  18. The Space Charge Effect on the Discharge Current in Cross-Linked Polyethylene under High AC Voltages

    Science.gov (United States)

    Kwon, Yoon-Hyeok; Hwangbo, Seung; Lee, June-Ho; Yi, Dong-Young; Han, Min-Koo

    2003-12-01

    The space charge distributions in solid dielectrics have been usually investigated by means of the pulsed electroacoustic (PEA) method. However, most previous studies have been limited to the phenomenological analysis under DC voltages. In our study, the space charge distribution in cross-linked polyethylene (XLPE) has been measured using AC voltages by means of the modified PEA method. Simultaneously, the streamer discharges in an air gap have been measured in order to investigate the relationship between space charge and discharge current, and the relationship has been adapted to the case of dielectric barrier discharge. At high AC voltages, discharge current increases to the critical point, but no further increase is exhibited over the critical voltage and the discharge pattern is resolved by the space charge. This result indicates that the frequency effect and space charge characteristics of dielectric materials are preferred to the voltage effect in the adaptation to dielectric barrier discharge. The results well explain the space charge effect on partial discharge and the dielectric barrier discharge phenomenon.

  19. Current situation and development of wind power in China

    Institute of Scientific and Technical Information of China (English)

    BAO Nengsheng; NI Weidou

    2007-01-01

    The current development of wind power in China was presented in this paper.Many regions such as Xinjiang Uygur Autonomous Region,Inner Mongolia Autonomous Region and southeast coastal region,etc.in China have abundant wind energy resource.At the same time,the utilization of wind power in China has been developing quickly and its prospect is promising in spite of many some obstacles.With the implementation of the Renewable Energy Law,some previous obstacles have been or are being eliminated.Much investment and many enterprises start to enter this field.In spite of this,there still exist some financial and technological obstacles.One of the technological obstacles is the stability of local power grid owing to the increasing proportion of the wind power capacity.Because the centralized development mode of wind power was adopted,the quick fluctuation of wind speed will influence the voltage and frequency stability of local power grid.In addition,large wind farm has little dispatching ability because of the uncontrollability,randomness and fluctuation of natural incoming wind.To erase these obstacles,a novel hybrid power system combining wind farm and small gas turbine power plants is discussed.

  20. A Streaming Potential/Current-Based Microfluidic Direct Current Generator for Self-Powered Nanosystems.

    Science.gov (United States)

    Zhang, Rui; Wang, Sihong; Yeh, Min-Hsin; Pan, Caofeng; Lin, Long; Yu, Ruomeng; Zhang, Yan; Zheng, Li; Jiao, Zongxia; Wang, Zhong Lin

    2015-11-01

    A simple but practical method to convert the hydroenergy of microfluids into continuous electrical output is reported. Based on the principle of streaming potential/current, a microfluidic generator (MFG) is demonstrated using patterned micropillar arrays as a quasi-porous flow channel. The continuous electrical output makes this MFG particularly suitable as a power source in self-powered systems. Using the proposed MFG to power a single nanowire-based pH sensor, a self-powered fluid sensor system is demonstrated.

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

    Science.gov (United States)

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

    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.

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

    Science.gov (United States)

    2010-06-01

    shown in Figure 38. HFA60MC60C Ultrafast, Soft Recovery Diode ) OLA T ED EASE VR = 00V + V(tYP ) = 1 V F 6OA Qrr (typ) 2000C DC power Motors ANGCE...Massachusetts Institute of Technology, 2009 [13] "LabJack UE9 User’s Guide," Mar . 10, 2010. [Online] Available: [Accessed May 12, 2010]. [14] E

  3. Critical current measurement for design of HTS DC power cables

    Science.gov (United States)

    Watanabe, Hirofumi

    2017-02-01

    Critical currents of HTS DC power cables were calculated. In the calculation a relationship between critical current density and magnetic flux density proposed by Gömöry et al. [1] was used and the parameters used in the relationship were obtained by the critical current measurements with respect to the external magnetic field for a sample of the HTS tape. Numerical models of cables were composed and their critical currents were calculated, which showed the strong dependence on the arrangement of the HTS tapes in the cable. Critical current measurements of model cables assembled based on the calculations showed that the measured critical currents also depended on the arrangement of the HTS tapes strongly. The calculated results were compared with the experimental results, which showed that the experimental results agreed well with the calculated results.

  4. MEMS electrostatic inductive transformer using potassium ion electrets for up- or down-conversion of AC current

    Science.gov (United States)

    Suzuki, Masato; Moriyama, Takashi; Toshiyoshi, Hiroshi; Hashiguchi, Gen

    2016-10-01

    In this paper, we report on a novel MEMS electrostatic inductive transformer using potassium ion electrets on mechanically movable silicon microelectrodes. The device consists of a pair of electrostatic comb drive actuators that share a common mass in the middle part of a spring-mass-spring system. When an excitation AC voltage is applied to the electrode of the input-port comb drive at its mechanical resonant frequency, the mass in the middle oscillates to generate electrostatic inductive charges on the electrodes of the output-port comb drive, which could be read out as an output current. By appropriately designing the ratio of force factors of input- and output-port comb drives, the device operates as a transformer to amplify the current at a high efficiency over of 90% under the optimal load condition.

  5. Current Advanced Power Generation Technologies and Options for China (2)

    Institute of Scientific and Technical Information of China (English)

    Deng Nubo; Mohsen Assadi; Yang Cheng

    2008-01-01

    @@ In China,electricity consumption keeps growing at a high speed and installed capacity will be doubled in the next fifteen years.As the world second CO2 producer and also a member of Kyoto Protocol,how to balance energy needs arid environmental protection responsibility in the future is a serious problem for China.As such,there are a number of technology choices for today's electric power generation.After discussing the current advanced power generation technologies based on Chinese energy structure and current conditions of power industry,this paper gives a reference to the technology options for China in the future.Here published is the second part of the paper.

  6. Damping effects of Supplementary Control Signals for Enhancement of Transient Stability in AC-DC Power Systems

    Directory of Open Access Journals (Sweden)

    Uma Vani M

    2010-07-01

    Full Text Available This paper discusses the impact of HVDC on Power System Stability and proposes a novel controlmechanism to augment the system angle stability. The effectiveness of the proposed controller is demonstrated by asingle machine-infinite bus system example. The performance of this controller, in comparison to the conventionalP and P-I controllers, is found to be very effective as a supplementary PID controller in damping generator rotoroscillations. The supplementary controls using signals derived from the AC systems to modulate the DC quantitiesis presented in this paper.

  7. A battery-powered high-current power supply for superconductors

    CERN Document Server

    Wake, M; Suda, K

    2002-01-01

    Since superconductors do not require voltages, a high-current power supply could run with low power if the voltage is sufficiently reduced. Even a battery-powered power supply could give as much as 2,000A for a superconductor. To demonstrate this hypothesis, a battery-powered 2,000A power supply was constructed. It uses an IGBT chopper and Schottky diode together with a specially arranged transformer to produce a high current with low voltage. Testing of 2,000A operation was performed for about 1.5 hr using 10 car batteries. Charging time for this operation was 8 hr. Ramping control was smooth and caused no trouble. Although the IGBT frequency ripple of 16.6 kHz was easily removed using a passive filter, spike noise remained in the output voltage. This ripple did not cause any trouble in operating a pancake-type inductive superconducting load. (author)

  8. Discharge current modes of high power impulse magnetron sputtering

    Directory of Open Access Journals (Sweden)

    Zhongzhen Wu

    2015-09-01

    Full Text Available Based on the production and disappearance of ions and electrons in the high power impulse magnetron sputtering plasma near the target, the expression of the discharge current is derived. Depending on the slope, six possible modes are deduced for the discharge current and the feasibility of each mode is discussed. The discharge parameters and target properties are simplified into the discharge voltage, sputtering yield, and ionization energy which mainly affect the discharge plasma. The relationship between these factors and the discharge current modes is also investigated.

  9. Robust low frequency current ripple elimination algorithm for grid-connected fuel cell systems with power balancing technique

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong-Soo; Choe, Gyu-Yeong; Lee, Byoung-Kuk [School of Information and Communication Engineering, Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon, Gyeonggi-do 440-746 (Korea, Republic of); Kang, Hyun-Soo [R and D Center, Advanced Drive Technology (ADT) Company, 689-26 Geumjeong-dong, Gunpo-si, Gyeonggi-do 435-862 (Korea, Republic of)

    2011-05-15

    The low frequency current ripple in grid-connected fuel cell systems is generated from dc-ac inverter operation, which generates 60 Hz fundamental component, and gives harmful effects on fuel cell stack itself, such as making cathode surface responses slower, causing an increase of more than 10% in the fuel consumption, creating oxygen starvation, causing a reduction in the operating lifetime, and incurring a nuisance tripping such as overload situation. With these reasons, low frequency current ripple makes fuel cell system unstable and lifetime of fuel cell stack itself short. This paper presents a fast and robust control algorithm to eliminate low frequency current ripple in grid-connected fuel cell systems. Compared with the conventional methods, in the proposed control algorithm, dc link voltage controller is shifted from dc-dc converter to dc-ac inverter, resulting that dc-ac inverter handles dc link voltage control and output current control simultaneously with help of power balancing technique. The results indicate that the proposed algorithm can not only completely eliminate current ripple but also significantly reduce the overshoot or undershoot during transient states without any extra hardware. The validity of the proposed algorithm is verified by computer simulations and also by experiments with a 1 kW laboratory prototype. (author)

  10. Pulse pattern modulated strategy for harmonic current components reduction in three-phase AC-DC converters

    DEFF Research Database (Denmark)

    Davari, Pooya; Zare, Firuz; Blaabjerg, Frede

    2015-01-01

    Generated harmonic current as a consequence of employing power electronics converter is known as an important power quality issue in distribution networks. From industry point of view complying with international standards is mandatory, however cost and efficiency are two other important features......, which need to be considered in order to be competitive in the market. Therefore, having a flexibility to meet various requirements imposed by the standard recommendations or costumer needs is at most desirable. This makes the generated harmonic current mitigation a challenging task especially with three......-phase diode bridge rectifier, which still is preferred in many power electronic systems. This paper addresses a novel current modulation strategy using a single-switch boost three-phase diode bridge rectifier. The proposed method can selectively mitigate current harmonics, which makes it suitable...

  11. Quench behavior of Sr0.6K0.4Fe2As2/Ag tapes with AC and DC transport currents at different temperature

    Science.gov (United States)

    Liu, Qi; Zhang, Guomin; Yang, Hua; Li, Zhenming; Liu, Wei; Jing, Liwei; Yu, Hui; Liu, Guole

    2016-09-01

    In applications, superconducting wires may carry AC or DC transport current. Thus, it is important to understand the behavior of normal zone propagation in conductors and magnets under different current conditions in order to develop an effective quench protection system. In this paper, quench behavior of Ag sheathed Sr0.6K0.4Fe2As2 (Sr-122 in the family of iron-based superconductor) tapes with AC and DC transport current is reported. The measurements are performed as a function of different temperature (20 K-30 K), varying transport current and operating frequency (50 Hz-250 Hz). The focus of the research is the minimum quench energy (MQE), the normal zone propagation velocity (NZPV) and the comparison of the related results with AC and DC transport current.

  12. Characterization of plasma electrolytic oxidation coatings on Zircaloy-4 formed in different electrolytes with AC current regime

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Yingliang, E-mail: chengyingliang@hnu.edu.cn [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Matykina, Enzhe [Dpt. Ciencia de los Materiales e Ingenieria Metalurgica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, Madrid 28040 (Spain); Skeldon, Peter; Thompson, George [Corrosion and Protection Centre, School of Materials, University of Manchester, Sackville Street, Manchester M13 9PL (United Kingdom)

    2011-10-01

    Highlights: > ZrO{sub 2} coatings are grown on Zircaloy-4 by AC plasma electrolytic oxidation. > Tetragonal and monoclinic ZrO{sub 2} are formed using silicate electrolyte. > Pyrophosphate electrolyte results in flawed coatings of monoclinic ZrO{sub 2}. > Silicate favours formation of tetragonal ZrO{sub 2}, with coating hardness {approx}8 GPa. > Microstructures are related to temperature gradients and solidification rates. - Abstract: Plasma electrolytic oxidation was undertaken on Zircaloy-4 in alkaline silicate and pyrophosphate electrolytes, with a square waveform AC current regime. The resultant coatings were examined using scanning electron spectroscopy, X-ray diffraction and nanoindentation. The coatings formed in silicate electrolyte comprised mainly a porous inner layer and a more compact outer layer, with characteristic solidification structures being evident following prolonged treatment. The coatings contained monoclinic and tetragonal ZrO{sub 2}, the latter being mainly present in the outer layer, which was of hardness up to {approx}8 GPa. In contrast, extensively cracked coatings resulted from use of pyrophosphate electrolyte; the coating integrity was improved by the addition of silicate to the pyrophosphate electrolyte. The different morphologies of the coatings appeared to be related to the differing nature of the microdischarges and to the incorporation of silicon species that enhanced the formation of t-ZrO{sub 2}.

  13. Comparative study between an alternating current (AC) and a direct current (DC) electrification of an urban railway

    OpenAIRE

    Garriga Turu, Jordi

    2015-01-01

    This study will evaluate technically, energetic and economically the traction electrification network of the line Barcelona – Vallès operated by Ferrocarrils de la Generalitat de Catalunya (FGC) in the existing voltage system (1500 Vdc) and a new electrification under alternative current (25 kVac) will be proposed to be as well studied. The results obtained will be compared in order to obtain decision factors on which system best fits.

  14. Complex state variable- and disturbance observer-based current controllers for AC drives

    DEFF Research Database (Denmark)

    Dal, Mehmet; Teodorescu, Remus; Blaabjerg, Frede

    2013-01-01

    , extracted by a disturbance observer and then injected into the current controller. In this study, a revised version of a disturbance observer-based controller and a well known complex variable model-based design with a single set of complex pole are compared in terms of design aspects and performance...... of the parameter and the cross-coupling effect. Moreover, it provides a better performance, smooth and low noisy operation with respect to the complex variable controller....... of the stator current. In order to improve the current control performance an alternative current control strategy was proposed previously aiming to avoid the undesired cross-coupling and non-linearities between the state variables. These effects are assumed as disturbances arisen in the closed-loop path...

  15. Virtual Impedance Based Fault Current Limiters for Inverter Dominated AC Microgrids

    DEFF Research Database (Denmark)

    Lu, Xiaonan; Wang, Jianhui; Guerrero, Josep M.

    2017-01-01

    In this paper, a virtual impedance based fault current limiter (VI-FCL) is proposed for islanded microgrids comprised of multiple inverter interfaced distributed generators (DGs). Considering the increased fault current capability induced by high penetration of renewable energy sources (RESs), FC......, and the stability analysis in consideration of VI-FCLs is thereby studied. MATLAB/Simulink model comprised of three inverter-interfaced DGs is implemented to verify the feasibility of the proposed method....

  16. High-current Standing Wave Linac With Gyrocon Power Source

    CERN Document Server

    Karliner, M M; Makarov, I G; Nezhevenko, O A; Ostreiko, G N; Persov, B Z; Serdobintsev, G V

    2004-01-01

    A gyrocon together with high-voltage 1.5 MeV accelerator ELIT-3A represents a power generator at 430 MHz serving for linear electron accelerator pulse driving. The facility description and results of calorimetric measurements of ELIT-3A electron beam power and accelerated beam at the end of accelerator are presented in the paper. 2.2 amps of pulsed current have been obtained at electron energy of 20 MeV. The achieved energy conversion efficiency is about 55%.

  17. AC over-current characteristics of YBCO coated conductor with copper stabilizer layer considering insulation layer

    Science.gov (United States)

    Du, H.-I.; Kim, M.-J.; Kim, Y.-J.; Lee, D.-H.; Han, B.-S.; Song, S.-S.

    2010-11-01

    Compared with the first-generation BSCCO wire, the YBCO thin-film wire boasts low material costs and high Jc and superior magnetic-field properties, among other strengths. Meanwhile, the previous BSCCO wire material for superconducting cables has been researched on considerably with regard to its post-wire quenching characteristics during the application of an alternating over-current. In this regard, the promising YBCO thin-film wire has yet to be further researched on. Moreover, still lacking is research on the YBCO thin-film wire with insulating layers, which is essential in the manufacture of superconducting cables, along with the testing of the application of an alternating over-current to the wire. In this study, YBCO thin-film wires with copper-stabilizing layers were used in testing alternating over-current application according to the presence or absence of insulating layers and to the thickness of such layers, to examine the post-quenching wire resistance increase and quenching trends. The YBCO thin-film wire with copper-stabilizing layers has a critical temperature of 90 K and a critical current of 85 A rms. Moreover, its current application cycle is 5.5 cycles, and its applied currents are 354, 517, 712, and 915 A peak. These figures enabled the YBCO thin-film wires with copper-stabilizing layers to reach 90, 180, 250, and 300 K, respectively, in this study. These temperatures serve as a relative reference to examine the post-quenching wire properties following the application of an alternating over-current.

  18. Condition assessment of power cables using partial discharge diagnosis at damped AC voltages

    NARCIS (Netherlands)

    Wester, F.J.

    2004-01-01

    The thesis focuses on the condition assessment of the distribution power cables, which have a very critical part in the distribution of electrical power over regional distances. The majority of the outages in the power system is related to the distribution cables, of which for more than 60% to inter

  19. An active damper for stabilizing power electronics-based AC systems

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Liserre, Marco

    2013-01-01

    The mutual interactions between the parallel grid-connected converters coupled through the grid impedance tend to result in a number of stability and power quality challenges. To address them, this paper proposes an active damper concept based on a low-power, high-bandwidth power converter. The b...

  20. A nontrivial factor in determining current distribution in an ac HTS cable-proximity effect

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A superconductor has zero resistance at the superconducting state. This unique property creates many exceptional phenomena, of which some are known and the others are not. Our experiments with multilayer high temperature superconductor (HTS) cable samples revealed a new phenomenon that alternating current had a tendency to flow in the inner and outer layers of the cables. We attribute the cause of this phenomenon to the electromagnetic interaction in an infinite electrical conductivity medium and term it "super-proximity-effect". This effect will greatly affect the performance of a multilayer superconducting cable and other superconducting devices which are involved with alternating current transportation.

  1. Online fault location on AC cables in underground transmission systems using screen currents

    DEFF Research Database (Denmark)

    Jensen, Christian Flytkjær; Nanayakkara, O.M.K.K; Rajapakse, Athula

    This paper studies online travelling wave methods for fault location on a crossbonded cable system using screen currents. During the construction of the electrical connection to the 400 MW off shore wind farm Anholt, it was possible to perform measurements on a 38.4 km crossbonded cable system...... coils if the screen currents contain the necessary information for accurate fault location. In this paper, this is examined by analysis of field measurements and through a study of simulations. The wavelet transform and visual inspection methods are used and the accuracy is compared. Field measurements...... and simulations are compared for testing the reliability of using simulations for studying fault location methods....

  2. Peltier ac calorimeter

    OpenAIRE

    Jung, D. H.; Moon, I. K.; Jeong, Y. H.

    2001-01-01

    A new ac calorimeter, utilizing the Peltier effect of a thermocouple junction as an ac power source, is described. This Peltier ac calorimeter allows to measure the absolute value of heat capacity of small solid samples with sub-milligrams of mass. The calorimeter can also be used as a dynamic one with a dynamic range of several decades at low frequencies.

  3. Hysteresis losses in MgB2 superconductors exposed to combinations of low AC and high DC magnetic fields and transport currents

    DEFF Research Database (Denmark)

    Magnusson, N.; Abrahamsen, Asger Bech; Liu, Dawei

    2014-01-01

    a simplified theoretical treatment of the hysteresis losses based on available models in the literature with the aim of setting the basis for estimation of the allowable magnetic fields and current ripples in superconducting generator coils intended for large wind turbine direct drive generators. The resulting...... equations use the DC in-field critical current, the geometry of the superconductor and the magnitude of the AC magnetic field component as parameters. This simplified approach can be valuable in the design of MgB2 DC coils in the 1–4T range with low AC magnetic field and current ripples....

  4. Multisim simulation test of RLC sinusoidal AC circuit power%RLC 正弦交流电路电量的 Multisim 仿真测试

    Institute of Scientific and Technical Information of China (English)

    腾香

    2013-01-01

      本文基于探索RLC正弦交流电路电量波形的Multisim仿真的目的,运用Multisim10软件对RLC正弦交流电路的特性进行了仿真实验分析,给出了Multisim仿真实验方案,仿真了电路中总电压、电流及各元件电压的相位关系,虚拟仿真实验结果与理论分析计算结果相一致,结论是仿真实验可直观形象地描述电路的工作特性。%To explore the Multisim simulation of RLC sinusoidal AC circuit power waveform , the paper car-ries out the simulation experiments to analyze the characteristics of RLC sinusoidal AC circuit by using Multi -sim10 software.The paper proposes the Multisim simulation scheme and simulates the phase relationship of the total voltage, the electric current and the voltage of each phase in the circuit .The simulation results are given to show that the results of virtual simulation and the theoretical analysis are consistent .The simulation experiment can intuitively and vividly describe the work characteristics of the circuit .

  5. Angular dependence of direct current decay in a closed YBCO double-pancake coil under external AC magnetic field and reduction by magnetic shielding

    Science.gov (United States)

    Geng, J.; Zhang, H.; Li, C.; Zhang, X.; Shen, B.; Coombs, T. A.

    2017-03-01

    High T c superconducting (HTS) coils are ideal candidates in the use of high field magnets. HTS coils carrying a direct current, however, suffer a non-negligible loss when they are exposed to an external AC magnetic field. Although this phenomenon is well known, no study concerning AC magnetic field angular dependence of direct current decay has ever been shown. In this work, we experimentally investigate the direct current decay characteristics in a closed double pancake coil made of a YBCO coated conductor under external AC field. AC field of different angles with respect to the coil plane is applied. Results show that the current decay rate presents a strong angular dependence. The fastest decay occurs when the field is parallel to the coil plane, in which case the surface of the tape in the outermost layer experiences most flux variation. To reduce the decay rate, we propose wrapping superconducting tapes around the outermost layer of the coil to shield external AC field. This method significantly reduces direct current decay rate under parallel field, without affecting the perpendicular self-field of the coil.

  6. Online Fault Location on AC Cables in Underground Transmission Systems using Sheath Currents

    DEFF Research Database (Denmark)

    Jensen, Christian Flytkjær; Nanayakkarab, Kasun; Rajapakse, Athula

    2014-01-01

    This paper studies online travelling wave methods for fault location on a crossbonded cable system using sheath currents. During the construction of the electrical connection to the 400 MW off shore wind farm Anholt, it was possible to perform measurements on a 38.4 km crossbonded cable system. A...

  7. Online fault location on AC cables in underground transmission systems using screen currents

    DEFF Research Database (Denmark)

    Jensen, Christian Flytkjær; Nanayakkara, O.M.K.K; Rajapakse, Athula

    This paper studies online travelling wave methods for fault location on a crossbonded cable system using screen currents. During the construction of the electrical connection to the 400 MW off shore wind farm Anholt, it was possible to perform measurements on a 38.4 km crossbonded cable system. A...

  8. Application of Multi-Objective Evolutionary Algorithm for Optimal Reactive Power Dispatch with Flexible AC Transmission System Devices

    Directory of Open Access Journals (Sweden)

    Abdarrazak OUALI

    2011-12-01

    Full Text Available Because their capability to change the network parameters with a rapid response and enhanced flexibility, flexible AC transmission system (FACTS devices have taken more attention in power systems operations as improvement of voltage profile and minimizing system losses. In this way, this paper presents a multi-objective evolutionary algorithm (MOEA to solve optimal reactive power dispatch (ORPD problem with FACTS devices. This nonlinear multi-objective problem (MOP consists to minimize simultaneously real power loss in transmission lines and voltage deviation at load buses, by tuning parameters and searching the location of FACTS devices. The constraints of this MOP are divided to equality constraints represented by load flow equations and inequality constraints such as, generation reactive power sources and security limits at load buses. Two types of FACTS devices, static synchronous series compensator (SSSC and unified power flow controller (UPFC are considered. A comparative study regarding the effects of an SSSC and an UPFC on voltage deviation and total transmission real losses is carried out. The design problem is tested on a 6-bus system.

  9. Containment and Consensus-based Distributed Coordination Control to Achieve Bounded Voltage and Precise Reactive Power Sharing in Islanded AC Microgrids

    DEFF Research Database (Denmark)

    Han, Renke; Meng, Lexuan; Ferrari-Trecate, Giancarlo

    2017-01-01

    This paper presents a novel distributed approach to achieve both bounded voltage and accurate reactive power sharing regulation in AC microgrid. The coupling/trade-off effects between bus voltages and reactive power sharing regulation are first analyzed in detail to provide a guideline for coordi...

  10. 直接AC/AC变换器输出电压及电流纹波分析%Analysis of Output Voltage and Current Ripple for Direct AC/AC Converter

    Institute of Scientific and Technical Information of China (English)

    文锋; 赵冉; 刘菁

    2009-01-01

    为解决直接AC/AC交换器的输出纹波计算问题,本文建立了以DC/DC变换器结构为基础的六种AC/AC变换器的理想模型.利用这些理想模型,DC/DC变换器的一般分析方法可方便地引入到AC/AC变换器的分析中,然后,论文以Buck型AC/AC变换器为例,给出其电路输出纹波系数的计算公式.为了证明理论分析的正确性,搭建了实验电路,实验结果与理论计算得到了很好的吻合.

  11. SURVEY ON DISTRIBUTED GENERATION BASED DIFFERENT MULTILEVEL DC-AC POWER INVERTER FOR HARMONIC REDUCTION

    OpenAIRE

    Meera, V.

    2017-01-01

    Multilevel inverter has been under research and development for more than three decades and has found successful industrial application. Also, it has become the enabling power conversion technology for high voltage and high power applications in present power systems and large electric motor drives. The propagated energy source consists of solar cells, wind turbines, micro-turbines (natural gas), fuel cells and storage batteries and also connected to the low voltage distribution network throu...

  12. Superconducting-magnetic heterostructures: a method of decreasing AC losses and improving critical current density in multifilamentary conductors.

    Science.gov (United States)

    Glowacki, B A; Majoros, M

    2009-06-24

    Magnetic materials can help to improve the performance of practical superconductors on the macroscale/microscale as magnetic diverters and also on the nanoscale as effective pinning centres. It has been established by numerical modelling that magnetic shielding of the filaments reduces AC losses in self-field conditions due to decoupling of the filaments and, at the same time, it increases the critical current of the composite. This effect is especially beneficial for coated conductors, in which the anisotropic properties of the superconductor are amplified by the conductor architecture. However, ferromagnetic coatings are often chemically incompatible with YBa(2)Cu(3)O(7) and (Pb,Bi)(2)Sr(2)Ca(2)Cu(3)O(9) conductors, and buffer layers have to be used. In contrast, in MgB(2) conductors an iron matrix may remain in direct contact with the superconducting core. The application of superconducting-magnetic heterostructures requires consideration of the thermal and electromagnetic stability of the superconducting materials used. On one hand, magnetic materials reduce the critical current gradient across the individual filaments but, on the other hand, they often reduce the thermal conductivity between the superconducting core and the cryogen, which may cause destruction of the conductor in the event of thermal instability. A possible nanoscale method of improving the critical current density of superconducting conductors is the introduction of sub-micron magnetic pinning centres. However, the volumetric density and chemical compatibility of magnetic inclusions has to be controlled to avoid suppression of the superconducting properties.

  13. An active damper for stabilizing power-electronics-based AC systems

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Liserre, Marco

    2014-01-01

    The interactions among the parallel grid-connected converters coupled through the grid impedance tend to result in stability and power quality problems. To address them, this paper proposes an active damper based on a high bandwidth power electronics converter. The general idea behind this propos...

  14. Coordinated Reactive Power and Voltage Management for Offshore Wind Farms with AC-connection

    DEFF Research Database (Denmark)

    Heussen, Kai

    2008-01-01

    This paper analyzes voltage and reactive power in a wind farm in dependence on switchable shunt and tap-changer settings in connection with the control ranges of flexible reactive power sources. Attention is paid to their interdependent effects on central control variables, such as voltage...... in the collection grid, reactive power exported to the grid and internal active power losses. An aggregated steady-state model of an offshore wind farm is presented and a reduced mathematical representation suitable for symbolic analysis is developed. A coordination scheme is proposed to coordinate fast continuous...... control inputs with slow tap-changing devices using a short-term prediction. The proposed scheme is aimed at balancing cost factors such as wear of switching components, active power loss within the wind farm and STATCOM capacity....

  15. Mechanical Extraction of Power From Ocean Currents and Tides

    Science.gov (United States)

    Jones, Jack; Chao, Yi

    2010-01-01

    A proposed scheme for generating electric power from rivers and from ocean currents, tides, and waves is intended to offer economic and environmental advantages over prior such schemes, some of which are at various stages of implementation, others of which have not yet advanced beyond the concept stage. This scheme would be less environmentally objectionable than are prior schemes that involve the use of dams to block rivers and tidal flows. This scheme would also not entail the high maintenance costs of other proposed schemes that call for submerged electric generators and cables, which would be subject to degradation by marine growth and corrosion. A basic power-generation system according to the scheme now proposed would not include any submerged electrical equipment. The submerged portion of the system would include an all-mechanical turbine/pump unit that would superficially resemble a large land-based wind turbine (see figure). The turbine axis would turn slowly as it captured energy from the local river flow, ocean current, tidal flow, or flow from an ocean-wave device. The turbine axis would drive a pump through a gearbox to generate an enclosed flow of water, hydraulic fluid, or other suitable fluid at a relatively high pressure [typically approx.500 psi (approx.3.4 MPa)]. The pressurized fluid could be piped to an onshore or offshore facility, above the ocean surface, where it would be used to drive a turbine that, in turn, would drive an electric generator. The fluid could be recirculated between the submerged unit and the power-generation facility in a closed flow system; alternatively, if the fluid were seawater, it could be taken in from the ocean at the submerged turbine/pump unit and discharged back into the ocean from the power-generation facility. Another alternative would be to use the pressurized flow to charge an elevated reservoir or other pumped-storage facility, from whence fluid could later be released to drive a turbine/generator unit at a

  16. Compact 40 kA 16,7 Hz switchgear for traction power supply; Kompakte 40-kA-Bahnschaltanlage fuer AC 15 kV 16,7 Hz

    Energy Technology Data Exchange (ETDEWEB)

    Kinscher, Jochen [Siemens AG, Erlangen (DE). Industry Sector Mobility Div. Complete Transportation (I MO CT); Jentzsch, Peter [Siemens AG, Berlin (DE). Industry Sector Mobility Div. Complete Transportation Power Supply Germany (I MO CT EL P)

    2011-10-15

    The air-insulated medium-voltage switchgear Sitras {sup registered} ASG 15 is the first type-tested compact switchgear that can be used in AC 15 kV 16,7 Hz traction power supplies with up to 40 kA short-circuit currents. Therefore, it meets all the demands on prefabricated switchgears for railway applications that railway system operators today are focusing on and is a best practice example for a successful adaption of components designed for the 50 Hz technology for 16,7 Hz traction power supplies. (orig.)

  17. Distributed Operation of Interlinked AC Microgrids with Dynamic Active and Reactive Power Tuning

    DEFF Research Database (Denmark)

    Nutkani, Inam Ullah; Loh, Poh Chiang; Blaabjerg, Frede

    2013-01-01

    Microgrids are small grids formed by clustering modern generating sources, storage systems, and loads together. Being independent, the formed microgrids can, in principle, operate at their own preferred voltages and frequencies. Tying them to the mains grid or another microgrid would therefore...... require some interlinking power converters, whose control should preferably be autonomous without depending on fast communication links. Contributing to this theme of research, a distributed power management scheme has been proposed in this paper for interlinking two or more independent microgrids...... operating at different voltages and frequencies. The proposed scheme allows sources in the microgrids to concentrate more on active power harnessing, while the interlinking converters focus more on meeting the load reactive demand. If necessary, backup active power from an underloaded microgrid can also...

  18. Characteristics of Overvoltage Protection with Cascade Application of Surge Protective Devices in Low-Voltage AC Power Circuits

    Directory of Open Access Journals (Sweden)

    RADULOVIC, V.

    2015-08-01

    Full Text Available Surge Protective Devices (SPDs are widely used for protection of the equipment in low-voltage AC power circuits against wide variety of surges. Cascade application of SPDs starting at the service entrance of a building and downstream toward near sensitive equipment is intended to ensure optimal energy distribution among installed SPDs, as well as proper equipment protection against surges. Characteristics of overvoltage protection with two-stage application of SPDs have been analyzed in the paper through performed measurements, followed by simulations and numerical modeling using the ATP/EMTP and MATLAB Simulink. Parametric analysis of the protection's characteristics in wide range of influencing factors has been performed in order to define a set of applicable solutions for proper selection and performance of SPDs.

  19. Power-Integrated Circuit Active Leakage Current Detector

    Directory of Open Access Journals (Sweden)

    M. F. Bulacio

    2012-01-01

    Full Text Available Most of the failures of induction motors become insulation faults, causing a permanent damage. Using differential current transformers, a system capable of insulation fault detection was developed, based on the differential relay protection scheme. Both signal injection and fault detection circuitry were integrated in a single chip. The proposed scheme is faster than other existing protection and not restricted to protect induction motors, but several other devices (such as IGBTs and systems. This paper explains the principle of operation of fault protection scheme and analyzes an integrated implementation through simulations and experimental results. A power-integrated circuit (PIC implementation is presented.

  20. Site Selection of Ocean Current Power Generation from Drifter Measurements

    Science.gov (United States)

    2014-12-01

    Peter C. Chu2, Ruo-Shan Tseng3 4 5 1 Department of Marine Biotechnology and Resources, National Sun Yat-sen University, 6 Kaohsiung 80424, Taiwan...Besides 105 Kuroshio, there is a strong current with a velocity of 1.2 m s-1 in the South China Sea 106 along the coast of Vietnam. Fig. 4 shows the...more 128 than 500 m is also being developed for Kuroshio power plant near Taitung [9]. The sea 129 depth near Taitung is often more than 500 m. Thus

  1. 交流电子负载中电感参数的选取%Inductor Parameters Selection of AC Power Electronic Load

    Institute of Scientific and Technical Information of China (English)

    严雪飞; 朱长青; 赵月飞; 安巧静; 侯立健

    2014-01-01

    For the purpose of fast tracking of the current, in this paper,the voltage PWM converter is used to realize the analogy of the load characteristics. And the hysteresis current control is used to control the AC current in order to realize the fast tracking. In view of lack of theoretical basis for the selection of inductance,the variation of the inductor current in AC power electronic load is analyzed,and the range of inductor parameters is designed with considering reference current tracing ,the switch frequency limit and current harmonics restraining and finally the range of the load inductance is determined and a simulation model was established in matlab/simulink. The simulation results show selection of the appropriate inductance helps to quickly track the reference current and improve the waveform quality,and the results also prove the effectiveness of this selection scheme.%为了实现电子负载中实际电流快速跟踪指令电流的目的,电路采用了电压型PWM变换器实现负载特性的模拟,通过滞环电流控制方法对交流侧电流进行控制来实现快速跟踪指令电流;针对电感选取缺乏理论基础的缺点,分析了交流电子负载中电感电流的变化规律,从快速跟踪指令电流、开关管频率限制以及抑制谐波三方面综合考虑给出了电感参数范围确定的方法,并最终确定了电子负载中电感的选取范围,最后在matlab/simulink中建立了仿真模型。仿真结果表明,选取合适的电感有助于快速跟踪指令电流和提高波形质量,同时也证明了该选取方案的有效性和可行性。

  2. New hybrid active power filter for harmonic current suppression and reactive power compensation

    Science.gov (United States)

    Biricik, Samet; Cemal Ozerdem, Ozgur; Redif, Soydan; Sezai Dincer, Mustafa

    2016-08-01

    In the case of undistorted and balanced grid voltages, low ratio shunt active power filters (APFs) can give unity power factors and achieve current harmonic cancellation. However, this is not possible when source voltages are distorted and unbalanced. In this study, the cost-effective hybrid active power filter (HAPF) topology for satisfying the requirements of harmonic current suppression and non-active power compensation for industry is presented. An effective strategy is developed to observe the effect of the placement of power capacitors and LC filters with the shunt APF. A new method for alleviating the negative effects of a nonideal grid voltage is proposed that uses a self-tuning filter algorithm with instantaneous reactive power theory. The real-time control of the studied system was achieved with a field-programmable gate array (FPGA) architecture, which was developed using the OPAL-RT system. The performance result of the proposed HAPF system is tested and presented under nonideal supply voltage conditions.

  3. Estimation and reduction of harmonic currents from power converters

    DEFF Research Database (Denmark)

    Asiminoaei, Lucian

    of estimation and reduction of the harmonic currents from industrial Adjustable Speed Drives, in order to come up with an optimized solution for customers. The work is structured in two main directions. The first direction consists of analyzing the mechanism of the harmonic current generation from ASD...... and harmonic rotating frame transformations, generalized harmonic integrators. Extensive simulations are employed in Matlab/Simulink and a laboratory stand is built to test the shunt APF topology. The actual implementation is done in fundamental rotating frame, where a new selective harmonic integrator....... Although the purpose of APF study was not finding a solution directly applicable for the Heat Power Station, there was an influence in the way the research line is further approached. As the cost of the APF is still relatively high, its utilization becomes more efficient for mediumor high...

  4. Adaptive Current Control Method for Hybrid Active Power Filter

    Science.gov (United States)

    Chau, Minh Thuyen

    2016-09-01

    This paper proposes an adaptive current control method for Hybrid Active Power Filter (HAPF). It consists of a fuzzy-neural controller, identification and prediction model and cost function. The fuzzy-neural controller parameters are adjusted according to the cost function minimum criteria. For this reason, the proposed control method has a capability on-line control clings to variation of the load harmonic currents. Compared to the single fuzzy logic control method, the proposed control method shows the advantages of better dynamic response, compensation error in steady-state is smaller, able to online control is better and harmonics cancelling is more effective. Simulation and experimental results have demonstrated the effectiveness of the proposed control method.

  5. Analysis and implementation of power management and control strategy for six-phase multilevel ac drive system in fault condition

    Directory of Open Access Journals (Sweden)

    Sanjeevikumar Padmanaban

    2016-03-01

    Full Text Available This research article exploits the power management algorithm in post-fault conditions for a six-phase (quad multilevel inverter. The drive circuit consists of four 2-level, three-phase voltage source inverter (VSI supplying a six-phase open-end windings motor or/impedance load, with circumstantial failure of one VSI investigated. A simplified level-shifted pulse-width modulation (PWM algorithm is developed to modulate each couple of three-phase VSI as 3-level output voltage generators in normal operation. The total power of the whole ac drive is shared equally among the four isolated DC sources. The developed post-fault algorithm is applied when there is a fault by one VSI and the load is fed from the remaining three healthy VSIs. In faulty conditions the multilevel outputs are reduced from 3-level to 2-level, but still the system propagates with degraded power. Numerical simulation modelling and experimental tests have been carried out with proposed post-fault control algorithm with three-phase open-end (asymmetrical induction motor/R-L impedance load. A complete set of simulation and experimental results provided in this paper shows close agreement with the developed theoretical background.

  6. Discrimination of Inrush Currents from Faults Current in Power Transformers using Gravitational Search Algorithm (GSA

    Directory of Open Access Journals (Sweden)

    Mohamad Kazem Daryabari

    2011-01-01

    Full Text Available The magnetizing inrush current phenomenon is a large transient condition, which occurs when a transformer is energized. The inrush current magnitude may be as high as ten times of transformer rated current that causes mal-operation of protection systems. Indeed, the similarity between signatures of Inrush current and internal fault condition make this failure. So, for safe running of a transformer, it is necessary to distinguish inrush current from fault currents. In this project, an Artificial Neural Network (ANN which is trained by two different swarm based algorithms; Gravitational Search Algorithm (GSA and Particle Swarm Optimization (PSO have been used to discriminate inrush current from fault currents in power transformers. GSA works based on gravity laws and in opposite of other swarm based algorithms, particles have identity and PSO is based on behaviors of bird flocking. Proposed approach has two general stages, in first step, obtained data from simulation have been processed and applied to ANN, and then in step two, using training data considered ANN has been trained by GSA & PSO. Proposed method has been compared with one of the common training approach which is called Back Propagation (BP and Results show that proposed method is so quick and can do discrimination very accurate.

  7. Flexible AC transmission systems: the state of the art

    Energy Technology Data Exchange (ETDEWEB)

    Edris, Abdel-Aty [Electric Power Research Inst., Palo Alto, CA (United States). Electric Systems Division

    1994-12-31

    Flexible AC transmission systems (FACTS) is a concept promoting the use of power electronic controllers to enhance the controllability and usable capacity of AC transmission. This paper presents the state of the art of FACTS and the status of the current projects for the application of the FACTS controllers in transmission systems. (author) 8 refs., 8 figs.

  8. AC Voltage Control of DC/DC Converters Based on Modular Multilevel Converters in Multi-Terminal High-Voltage Direct Current Transmission Systems

    Directory of Open Access Journals (Sweden)

    Rui Li

    2016-12-01

    Full Text Available The AC voltage control of a DC/DC converter based on the modular multilevel converter (MMC is considered under normal operation and during a local DC fault. By actively setting the AC voltage according to the two DC voltages of the DC/DC converter, the modulation index can be near unity, and the DC voltage is effectively utilized to output higher AC voltage. This significantly decreases submodule (SM capacitance and conduction losses of the DC/DC converter, yielding reduced capital cost, volume, and higher efficiency. Additionally, the AC voltage is limited in the controllable range of both the MMCs in the DC/DC converter; thus, over-modulation and uncontrolled currents are actively avoided. The AC voltage control of the DC/DC converter during local DC faults, i.e., standby operation, is also proposed, where only the MMC connected on the faulty cable is blocked, while the other MMC remains operational with zero AC voltage output. Thus, the capacitor voltages can be regulated at the rated value and the decrease of the SM capacitor voltages after the blocking of the DC/DC converter is avoided. Moreover, the fault can still be isolated as quickly as the conventional approach, where both MMCs are blocked and the DC/DC converter is not exposed to the risk of overcurrent. The proposed AC voltage control strategy is assessed in a three-terminal high-voltage direct current (HVDC system incorporating a DC/DC converter, and the simulation results confirm its feasibility.

  9. A low-power current self-adjusted VCO using a bottom PMOS current source

    Science.gov (United States)

    Zhixiong, Sheng; Fengqi, Yu

    2014-09-01

    This paper presents the design and implementation of a current self-adjusted VCO with low power consumption. In the proposed VCO, a bottom PMOS current source instead of a top one is adopted to decrease the tail noise. A current self-adjusted technique without additional external control signals is taken to ensure the VCO starts up in the whole band while keeping the power consumption relatively low. Meanwhile, the phase noise of the VCO at the low frequency (high Cvar) can be reduced by the technique. The circuit is implemented in 0.18 μm CMOS technology. The proposed VCO exhibits low power consumption of < 1.6 mW at a 1.5 V supply voltage and a tuning range from 11.79 to 12.53 GHz. The measured phase noise at 1 MHz offset from the frequency 11.79 GHz is -104.7 dBc/Hz, and the corresponding FOM is -184.2 dBc/Hz.

  10. Recent TCP(Tidal Current Power) projects in Korea

    Institute of Scientific and Technical Information of China (English)

    Chul; Hee; JO; Kang; Hee; LEE; Yu; Ho; RHO

    2010-01-01

    Having strong current on the west coast with up to 10 m tidal range in Korea,there are many suitable and applicable locations for TCP(Tidal Current Power) application in Korea.Not only the west coast,but also the south west regions having narrow channels between islands creating fast ocean stream are suitable for TCP.The first TCP application in Korea is 1 MW helical VAT(Vertical Axis Turbine) device installed in Wooldolmog area in 2008.The first HAT(Horizontal Axis Turbine) TCP device of 25 KW was developed and installed in cooling water weir of Samchonpo power plant in 2008.Furthermore,a 100 kW prototype HAT TCP device is being planned to be installed in Daebang strait in 2009.Another big project would be Inchon TCP farm of 200 MW on the west coast in Korea.The consortium of 5 members was formed in April,2009.This site will be the largest TCP site in the world.The paper describes recent TCP projects in Korea with background and environmental conditions of the projects.

  11. CONCEPTS OF IMPROVING CURRENT PROTECTION OF POWER-GRID LINES

    Directory of Open Access Journals (Sweden)

    F. A. Romaniuk

    2015-01-01

    Full Text Available The  6–35  kV  power-grid  current  protection  serves  to  protect  the  transmission  lines against phase-to-phase short-circuits. The major disadvantage of it lies in the relatively large time delays of the last stages especially in the main sections of the grid owing to the stepped relay characteristics as well as a large number of the steps. A full-fledged protection of the 6–35 kV lines against inter-phase short circuits can be provided by the two-stage current protection: the first stage being the current cutoff without any time delay and the second stage – the maximum current protection where the time delay is linear contingent on the distance between the protection placement and the fault-point location. The article introduces the rating formulae for the time delays of the second-stage and their exemplary graphic presentation. The authors offer a variant for solving the problem with computation of the second-stage time delays in those instances where several feeders diverge from the bus bars of the substation located in the end of the protected line.Improving current protections for the 6–35 kV transmission lines with one-end power supply against interphase short-circuits can be based on the collective application of the following principles: accounting for the type and location of the short-circuit which provides for the high-performance cutoff zone instantaneous expansion and its independence on the mode of failure and the grid operation mode. It also allows increase of the last stage sensitiveness towards asymmetrical short-circuits; detection of the short-circuit location only on the results of fault currents measurement which simplifies the protection implementation; realization of the last (second protection stage with linear-dependent time delay which ensures potentiality of its operation speed increase.

  12. Linear Decentralized Power Sharing Schemes for Economic Operation of AC Microgrids

    DEFF Research Database (Denmark)

    Nutkani, Inam Ullah; Loh, Poh Chiang; Wang, Peng;

    2016-01-01

    This paper presents two linear power sharing schemes for distributed generators (DGs). The purpose is to reduce the total generation cost (TGC) of the considered autonomous microgrid. The saving in cost is realized by tuning the DG droop gradients in accordance to their respective maximum or mean...

  13. Hysteresis losses in MgB{sub 2} superconductors exposed to combinations of low AC and high DC magnetic fields and transport currents

    Energy Technology Data Exchange (ETDEWEB)

    Magnusson, N., E-mail: niklas.magnusson@sintef.no [SINTEF Energy Research, NO-7465 Trondheim (Norway); Abrahamsen, A.B. [DTU Wind Energy, Technical University of Denmark, DK-4000 Roskilde (Denmark); Liu, D. [Electrical Power Processing Group, TU Delft, Mekelweg 4, NL-2628 CD Delft (Netherlands); Runde, M. [SINTEF Energy Research, NO-7465 Trondheim (Norway); Polinder, H. [Electrical Power Processing Group, TU Delft, Mekelweg 4, NL-2628 CD Delft (Netherlands)

    2014-11-15

    Highlights: • A method for calculating hysteresis losses in the low AC – high DC magnetic field and transport current range has been shown. • The method can be used in the design of wind turbine generators for calculating the losses in the generator DC rotor. • First estimates indicate tolerable current ripple in the 0.1% range for a 4 T DC MgB{sub 2} generator rotor coil. - Abstract: MgB{sub 2} superconductors are considered for generator field coils for direct drive wind turbine generators. In such coils, the losses generated by AC magnetic fields may generate excessive local heating and add to the thermal load, which must be removed by the cooling system. These losses must be evaluated in the design of the generator to ensure a sufficient overall efficiency. A major loss component is the hysteresis losses in the superconductor itself. In the high DC – low AC current and magnetic field region experimental results still lack for MgB{sub 2} conductors. In this article we reason towards a simplified theoretical treatment of the hysteresis losses based on available models in the literature with the aim of setting the basis for estimation of the allowable magnetic fields and current ripples in superconducting generator coils intended for large wind turbine direct drive generators. The resulting equations use the DC in-field critical current, the geometry of the superconductor and the magnitude of the AC magnetic field component as parameters. This simplified approach can be valuable in the design of MgB{sub 2} DC coils in the 1–4 T range with low AC magnetic field and current ripples.

  14. Intrawire resistance, AC loss and strain dependence of critical current in MgB2 wires with and without cold high-pressure densification

    NARCIS (Netherlands)

    Zhou, C.; Gao, P.; Krooshoop, H.J.G.; Dhallé, M.M.J.; Sumption, M.D.; Rindfleisch, M.; Tomsic, M.; Küllich, M.; Senatore, C.; Nijhuis, A.

    2014-01-01

    The intrawire resistance and alternating current (AC) loss of two MgB2 wires with filaments surrounded by Nb barriers have been measured and analyzed. Relatively high values of filament-to-matrix contact resistivity are found in the MgB2 wires; the values are two or three orders higher than those co

  15. Design of an AC/DC power supply for telecom applications

    Energy Technology Data Exchange (ETDEWEB)

    Suntio, T.; Vallittu, P.; Laurinen, T.; Ikonen, M. [Efore Oy, Espoo (Finland)

    1997-12-31

    Typical Telecom uninterruptible power supply system (UPS) comprises of parallel connected rectifiers and storage batteries supplying DC power for Telecom switching systems on fixed or mobile telephone networks. The requirement is most often of total uninterruptibility meaning high reliability and availability performance as a vital design and development goal. The Telecom systems must also meet stringent noise emission and immunity requirements stipulated by EMC and Low Voltage Directives, European Telecommunications Standard Institute (ETSI) as well as other global and local standards depending on the area they are to be used. This paper will describe in practice the vital features the rectifiers should contain as well as presents results from a practical equipment of 48 V, 500 W. (orig.) 27 refs.

  16. Critical-current density of melt-grown single-grain Y-Ba-Cu-O disks determined by ac susceptibility measurements

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D-X [ICREA and Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain); Sanchez, A; Navau, C [Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain); Shi, Y-H; Cardwell, D A [Engineering Department, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ (United Kingdom)

    2008-08-15

    The field amplitude and frequency dependent complex ac susceptibility {chi}(H{sub m},f) of three Y-Ba-Cu-O disks made by a top-seeded melt growth technique has been measured at 77 K with the ac field applied along the c-axis of the samples (parallel to their thickness). A procedure based on the Bean model has been developed to calculate the critical-current density J{sub c} near the surface of the sample from the measured {chi}(H{sub m}) for the case where the maximum imaginary component {chi}{sup ''} is not reached.

  17. Simulation and performance enhancement of the air cooling system in a DC/AC power converter station

    Energy Technology Data Exchange (ETDEWEB)

    Lozowy, R.; El-Shaboury, A.; Soliman, H.; Ormiston, S. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Mechanical and Manufacturing Engineering

    2010-07-01

    This study analyzed the flow structure and heat transfer in a large 3-dimensional domain with turbulence, mixed convection, an impinging jet, and flow over heated blocks. The objective was to better understand turbulent mixed-convection cooling of heat-generating bodies in 3-dimensional enclosures, which is important to industry. The cooling of 2 thyristor valve halls was simulated. Each valve hall housed 3 towers that contained electronics used in DC/AC power conversion. The simulation results included the magnitudes of the net air flows for all the inter-block gaps and the maximum temperature in each gap. A parametric study was also performed to investigate the effects of the air inlet location, size and aspect ratio. The effects of the air injection angle on cooling effectiveness was also examined. The study showed that for fixed inlet mass flow rate, significant improvement in the cooling effectiveness can be obtained by changing the injection angle of the inlet air jet, the location of the inlet grill, or the size of the inlet grill. It was concluded that these study results may be relevant to other applications, such as the design of power transformers, the design of cooling systems for spent nuclear fuel and computer server cooling racks. 13 refs., 12 figs.

  18. 基于DDS技术的交流恒流源设计%Design of AC constant current source based on DDS

    Institute of Scientific and Technical Information of China (English)

    黄怡然; 李娜

    2011-01-01

    The design and the implement method of AC constant current source with the ML2035 sine signal generator based on DOS was introduced in this paper, the AC constant current source was a closed-loop control system, and current negative feedback loop circuit. The testing results show the output current is between 100-200 mA.%介绍了运用直接数字合成技术( DDS )研制的ML2035正弦信号发生器来实现交流恒流源的设计思想和实现方法.该恒流源是一闭环控制系统、电流负反馈电路,测试结果表明,输出电流在100~ 200 mA范围内.

  19. Technical Papers for the Third Symposium on EHV AC Power Transmission. US-USSR Joint Committee on Cooperation in the Field of Energy.

    Energy Technology Data Exchange (ETDEWEB)

    Joint American-Soviet Committee on Cooperation in the Field of Energy.

    1982-05-10

    Eleven papers prepared for presentation at a symposium to be held during 1982 in the USA on scientific cooperation between the US and USSR in the field of research, design and operation of ehv/uhv ac and dc power transmission systems are included. A separate abstract was prepared for each paper. (LCL)

  20. Influence of Critical Current Density on Guidance Force Decay of HTS Bulk Exposed to AC Magnetic Field Perturbation in a Maglev Vehicle System

    Science.gov (United States)

    Longcai, Zhang; Jianguo, Kong

    2012-07-01

    Superconducting maglev vehicle is one of the most promising applications of HTS bulks. In such a system, the HTS bulks are always exposed to AC external magnetic field, which is generated by the inhomogeneous surface magnetic field of the NdFeB guideway. In our previous work, we studied the guidance force decay of the YBCO bulk over the NdFdB guideway used in the High-temperature superconducting maglev vehicle system with the application of the AC external magnetic field, and calculated the guidance force decay as a function of time based on an analytic model. In this paper, we investigated the influence of the critical current density on the guidance force decay of HTS bulk exposed to AC field perturbation in the maglev vehicle system and try to adopt a method to suppress the decay. From the results, it was found that the guidance force decay rate was higher for the bulk with lower critical current density. Therefore, we could suppress the guidance force decay of HTS bulk exposed to AC external magnetic field perturbation in the maglev vehicle system by improving critical current density of the bulk.

  1. Current regulations and state investment in the wind power projects

    Directory of Open Access Journals (Sweden)

    Danijela Simeunović

    2015-09-01

    Full Text Available It is the objective of this paper to present the path which the wind farm projects have undergone in Croatia from their introduction and expansion since the year 2007 up to the today's date when their development is temporarily stayed. The paper first describes the political and legal framework for renewable energy sources in Croatia, and specifically for wind power plants, as well as the current status of investment in building of wind farms in Croatia. The paper further analyses why the Croatian system of promotion of eligible producers has proven to attract investment, albeit unsustainable for a longer period of time, and which regulatory measures have later contributed to the suspension of wind farm investment in 2014. Legal and factual consequences of such suspension are discussed at the end of the paper, as well as some potential new business models for further exploitation of wind energy in Croatia.

  2. The AC Impedance Characteristic of High Power Li4Ti5O12-based Battery Cells

    DEFF Research Database (Denmark)

    Stroe, Ana-Irina; Stroe, Daniel Loan; Swierczynski, Maciej Jozef

    2015-01-01

    This paper studies the impedance characteristics of a fresh 13 Ah high-power lithium titanate oxide (LTO) battery cell and analyses its dependence on the temperature and state-of-charge. The impedance of the battery cell was measured by means of the electrochemical impedance spectroscopy (EIS......) technique for the entire state-of-charge (SOC) interval and considering five temperatures between 5oC and 45oC. By analyzing the measured impedance spectra of the LTO-based battery cell, it was found out that the cell’s impedance is extremely dependent on the operating conditions. By further processing...

  3. AC/DC Smart Control And Power Sharing of DC Distribution Systems

    Science.gov (United States)

    2012-02-10

    ISRCS 2011, Boise, Idaho, USA, Pages 89-84, IEEE Xplore DOI 10.1109/ISRCS.2011.6016095, Aug 9-11, 2011. 8. A. Mohamed, M. Elshaer and O. A...Manooth, “A Survey of Systems to Integrate Distributed Energy Resources and Energy Storage on the Utility Grid,” in IEEE 2008 Energy 2030 Conf., 2008...Georgia, USA. [2] H. Puttgen, P. MacGregor, F. Lambert, “Distributed Generation: Semantic Hype or the Dawn of a New Era,” IEEE Power and Energy

  4. Harmonic content in the variable-frequency ac power line of TFTR

    Energy Technology Data Exchange (ETDEWEB)

    Zabar, Z.; Bronner, G.; McMurray, S.; Karady, G.

    1979-12-01

    Studies were made of the harmonic content of the current and voltage at the generator bus of the Tokamak Fusion Test Reactor. Out of numerous load scenarios, one case was considered in detail. The harmonics were found acceptable for the generator; however, control problems and substantial telecommunications interference may result, requiring appropriate control measures and shielded telecommunication lines.

  5. Beta band transcranial alternating (tACS and direct current stimulation (tDCS applied after initial learning facilitate retrieval of a motor sequence

    Directory of Open Access Journals (Sweden)

    Vanessa eKrause

    2016-01-01

    Full Text Available The primary motor cortex (M1 contributes to the acquisition and early consolidation of a motor sequence. Although the relevance of M1 excitability for motor learning has been supported, the significance of M1 oscillations remains an open issue. This study aims at investigating to what extent retrieval of a newly learned motor sequence can be differentially affected by motor-cortical transcranial alternating (tACS and direct current stimulation (tDCS. Alpha (10 Hz, beta (20 Hz or sham tACS was applied in 36 right-handers. Anodal or cathodal tDCS was applied in 30 right-handers. Participants learned an eight-digit serial reaction time task (SRTT; sequential vs. random with the right hand. Stimulation was applied to the left M1 after SRTT acquisition at rest for ten minutes. Reaction times were analyzed at baseline, end of acquisition, retrieval immediately after stimulation and reacquisition after eight further sequence repetitions.Reaction times during retrieval were significantly faster following 20 Hz tACS as compared to 10 Hz and sham tACS indicating a facilitation of early consolidation. TDCS yielded faster reaction times, too, independent of polarity. No significant differences between 20 Hz tACS and tDCS effects on retrieval were found suggesting that 20 Hz effects might be associated with altered motor-cortical excitability. Based on the behavioural modulation yielded by tACS and tDCS one might speculate that altered motor-cortical beta oscillations support early motor consolidation possibly associated with neuroplastic reorganization.

  6. Sensitivity Analysis of Core Damage from Reactor Coolant Pump Seal Leakage during Extended Loss of All AC Power

    Energy Technology Data Exchange (ETDEWEB)

    Park, Da Hee; Kim, Min Gi; Lee, Kyung Jin; Hwang, Su hyun; Lee, Byung Chul [FNC Technology Co. Ltd., Yongin (Korea, Republic of); Yoon, Duk Joo; Lee, Seung Chan [Korea Hydro and Nuclear Power Co. Ltd., Daejeon (Korea, Republic of)

    2015-10-15

    In this study, in order to comprehend the Fukushima accident, the sensitivity analysis was performed to analyze the behavior of Reactor Coolant System (RCS) during ELAP using the RELAP5/MOD3.3 code. The Fukushima accident was caused by tsunami resulted in Station Black Out (SBO) followed by the reactor core melt-down and release of radioactive materials. After the accident, the equipment and strategies for the Extended Loss of All AC Power (ELAP) were recommended strongly. In this analysis, sensitivity studies for the RCP seal failure of the OPR1000 type NPP were performed by using RELAP5/MOD3.3 code. Six cases with different leakage rate of RCP seal were studied for ELAP with operator action or not. The main findings are summarized as follows: (1) Without the operator action, the core uncovery time is determined by the leakage rate of RCP seal. When the leakage rate per RCP seal are 5 gpm, 50 gpm, and 300 gpm respectively, the core uncovery time are 1.62 hr, 1.58 hr, and 1.29 hr respectively. Namely, If the leakage rate of RCP seal was much bigger, the uncover time of core would be shorter. (2) In case that the cooling by SG secondary side was performed using the TDAFP and SG ADV, the core uncovery time was significantly extended.

  7. Flex concept for US-A BWR extended loss of AC power events

    Energy Technology Data Exchange (ETDEWEB)

    Powers, J. [Toshiba America Nuclear Energy, Charlotte, North Carolina (United States); Aoyagi, Y.; Kataoka, K. [Toshiba Corporation, Kawasaki, Kanagawa (Japan); Thomas, S.; Mookhoek, B., E-mail: jim.powers@toshiba.com [Nuclear Innovation North America, Lake Jackson, Texas (United States)

    2015-09-15

    The US-Advanced Boiling Water Reactor (US-A BWR), certified by the US NRC, is a third generation, evolutionary boiling water reactor design which is the reference for the South Texas Project Units 3 and 4 (Stp 3 and 4) Combined License Application (Cola) and incorporates numerous design and technology enhancements for improved safety performance. Nuclear Innovation North America (NINA) is the License Applicant for this new build project, and Toshiba is the selected primary technology contractor. The Stp 3 and 4 project has finished the US NRC technical review of the Cola, and the final safety evaluation report (FSER) is scheduled to be issued by the US NRC in 2015. Following the accident at the Fukushima Dai-ichi plant, the US-A BWR was reviewed for Beyond Design Basis Event (BDBE) safety using industry and regulatory guidance for US NRC Order EA-12-049 Order Modifying Licenses with Regard to Requirements for Mitigation of Beyond Design Basis External Events (BDBEE). By virtue of the design approach, the US-A BWR is capable of providing an indefinite coping period for a station blackout. The use of installed systems with extended coping times is a significant advantage of the US-A BWR compared to most of the plants currently operating in the U.S. In addition, the Stp 3 and 4 design incorporates enhancements consistent with the current US industry Diverse and Flexible Coping Strategies (Flex) initiative. The final technical topic requiring review by the US NRC Advisory Committee on Reactor Safeguards was the Flex Integrated Plan submitted by NINA, and this review was successfully completed. This paper summarizes the progress of the US-A BWR in licensing the Flex Integrated Plan for the project, and describes the technology and features of the US-A BWR design that contribute to safety post-Fukushima. It also provides an informational comparison of the design capabilities of the US-A BWR for extreme external events, and relates these capabilities to re

  8. Liquid helium boil-off measurements of heat leakage from sinter-forged BSCCO current leads under DC and AC conditions

    Science.gov (United States)

    Cha, Y. S.; Niemann, R. C.; Hull, J. R.; Youngdahl, C. A.; Lanagan, M. T.; Nakade, M.; Hara, T.

    1995-06-01

    Liquid helium boil-off experiments are conducted to determine the heat leakage rate of a pair of BSCCO 2223 high-temperature superconductor current leads made by sinter forging. The experiments are carried out in both DC and AC conditions and with and without an intermediate heat intercept. Current ranges are from 0-500 A for DC tests and 0-1,000 A(sub rms) for AC tests. The leads are self-cooled. Results show that magnetic hysteresis (AC) losses for both the BSCCO leads and the low-temperature superconductor current jumper are small for the current range. It is shown that significant reduction in heat leakage rate (liquid helium boil-off rate) is realized by using the BSCCO superconductor leads. At 100 A, the heat leakage rate of the BSCCO/copper binary lead is approximately 29% of that of the conventional copper lead. Further reduction in liquid helium boil-off rate can be achieved by using an intermediate heat intercept. For example, at 500 K, the heat leakage rate of the BSCCO/copper binary lead is only 7% of that of the conventional copper lead when an intermediate heat intercept is used.

  9. 基于IGBT的交流固态功率控制器设计%Design of AC Solid-State Power Controller Based on IGBT

    Institute of Scientific and Technical Information of China (English)

    刘建英; 刘鹏飞; 马敏; 杨占刚; 李新健

    2014-01-01

    Solid state power controller ( SSPC) is a solid state device which is used to replace the relay’s role of switching and the breaker’s role of protection.It’s a switch matching with solid state distribution system.SSPC has the advantages of no noise, reacting quickly no electronic contact,no electronic arc,high reliability and so on.Therefore,an AC power switch based on insula-ted gate bipolar transistor(IGBT) at reverse tandem structure was presented.By replacing the complex signal processing circuit, AC-DC converter AD736 was used to convert capacitance sensor output into digital signal directly,simplify the electronics,and minimiz the interference of distributed and parasitic capacitance.Experiment result shows that the system meets the requirement of accuracy,and acquires good performance on the over-current protection of inverse-time.%固态功率控制器( SSPC)是集断路器线路保护功能和固态继电器可靠性于一体的智能开关装置,具有开关速度快、无触点、无电弧、可靠性高等特点。为此,以基于绝缘栅双极型晶体管( IGBT)反向串联结构为交流功率开关,研制了交流固态功率控制器。应用交流-直流真有效值转换芯片AD736,将传感器的输出直接转换为直流信号,省去了前端复杂的信号调理电路,简化了设计,并且有效地降低了寄生电容和杂散电容的影响。实验表明:设计的交流固态功率控制器原理样机满足测量精度要求,并验证了对负载反时限过流保护功能。

  10. Design of a Solid-State Fast Voltage Compensator for klystron modulators requiring constant AC power consumption

    CERN Document Server

    Aguglia, Davide; Viarouge, Philippe; Cros, Jerome

    2014-01-01

    This paper proposes a novel topological solution for klystron modulators integrating a Fast Voltage Compensator which allows an operation at constant power consumption from the utility grid. This kind of solution is mandatory for the CLIC project under study, which requires several hundreds of synchronously operated klystron modulators for a total pulsed power of 39 GW. The topology is optimized for the challenging CLIC specifications, which require a very precise output voltage flat-top as well as fast rise and fall times (3µs). The Fast Voltage Compensator is integrated in the modulator such that it only has to manage the capacitor charger current and a fraction of the charging voltage. Consequently, its dimensioning power and cost is minimized.

  11. Hysteresis Current Control technique based on Space Vector Modulation for Active Power Filter

    Directory of Open Access Journals (Sweden)

    Wang Yun-liang

    2011-09-01

    Full Text Available In this paper, the hysteresis current control (HCC technique based on space vector modulation (SVM for shunt active power filter (APF is proposed. The switching control algorithms of the HCC based SVM manage to generate compensated current according to the reference current. Harmonics extraction is based on the instantaneous active and reactive power theorem in time domain by calculating the power compensation. A closed loop control system is carried out and the error current is the difference between the reference current which is obtained from the power compensation and the actual current needs to be injected back into the power grid. By implementing this control strategy, the APF manages to generate better compensated harmonics currents to the power grid. Keywords: active power filter, hysteresis current control, space vector modulation ,matlab/simulink

  12. Design of wide output voltage AC-DC power supply based on buck-boost circuit%基于Buck-Boost电路的宽输出电压AC-DC电源设计

    Institute of Scientific and Technical Information of China (English)

    徐文城; 刘尧; 王秀荣

    2012-01-01

    设计了一种宽输出电压的AC DC开关电源,其主要特征是输出电压可以在较大范围内任意调节,解决了传统的开关电源只能输出几个特定电压值的问题.该设计的核心是反激变换电路和Buck-Boost电路.分析了这两种电路的工作原理及其应用,并且给出了具体的设计.实验表明,设计的电源能较好地实现了输出电压的宽范围调节.%AC-DC switching power supply with a wide range voltage output was designed. Its main feature is that the output voltage can be adjusted in a wide range. The problem that the traditional switching power supplies only have few specific voltage outputs is solved in the design. The flyback convert circuit and Buck-Boost circuit are the cores of the design. The working principle and applications of these two circuits are analyzed. The concrete design is given in this paper. The experiments show that a wide range regulation of the output voltage has been more successfully achieved in the design of the power supply.

  13. Protection of AC and DC Microgrids

    DEFF Research Database (Denmark)

    Beheshtaein, Siavash; Savaghebi, Mehdi; Quintero, Juan Carlos Vasquez

    2015-01-01

    In future, distributed energy resources (RESs) will be utilized at consumption points. As a consequence, power flow and fault current would be bidirectional and topologydependent; and hence the conventional protection strategies would be inefficient. This paper categorizes the main challenges in AC...

  14. ACAC Converters for UPS

    Directory of Open Access Journals (Sweden)

    Rusalin Lucian R. Păun

    2008-05-01

    Full Text Available This paper propose a new control technique forsingle – phase ACAC converters used for a on-line UPSwith a good dynamic response, a reduced-partscomponents, a good output characteristic, a good powerfactorcorrection(PFC. This converter no needs anisolation transformer. A power factor correction rectifierand an inverter with the proposed control scheme has beendesigned and simulated using Caspoc2007, validating theconcept.

  15. A Correlation Based Method for Discriminating Inrush Current from Short Circuit Current Using Wavelet Transform in Power Transformer Differential Protection

    Directory of Open Access Journals (Sweden)

    M. Rasoulpoor

    2013-09-01

    Full Text Available This paper presents a new approach for power transformer differential protection. The Wavelet Transform is applied to discriminate between inrush currents and internal fault currents in power transformers. Discrete wavelet transform decomposes the current signal into sub-bands that give more information about the properties of the signals in different frequency bands. Also, this transform is used to investigate the energy distribution of the signal on the different time and frequency scales. Recognition method is based on the correlation factors between energy percentage vectors of the Wavelet coefficients. Discrete Wavelet transform is used for decomposing the current signals to different frequency coefficients. After that, by constituting the energy percentage vectors of wavelet transform coefficients and calculating the correlation factors between these vectors, it is possible to form a recognition criterion to distinguish between inrush and internal fault current in the proposed method. The proposed algorithm is tested for several conditions by simulated inrush and internal fault currents. Simulation of current signals is performed using electromagnetic transient program PSCAD/EMTDC software that is a powerful program for the investigation of transient signals. Simulation results show that the proposed scheme accurately identifies inrush and fault currents in the distance of the power transformer protection in less than quarter of power frequency cycle. Also, beside the sensitivity and high reliability, the proposed method has low computation content and unlike the common methods does not require to determine the threshold for each new power system.

  16. Investigation and comparison of AC losses on stabilizer-free and copper stabilizer HTS tapes

    Science.gov (United States)

    Shen, Boyang; Li, Jing; Geng, Jianzhao; Fu, Lin; Zhang, Xiuchang; Li, Chao; Zhang, Heng; Dong, Qihuan; Ma, Jun; Coombs, T. A.

    2017-10-01

    This paper presents the measurement and simulation of Alternating Current (AC) losses on the Stabilizer-free and Copper Stabilizer High Temperature Superconducting (HTS) Tapes: SuperPower SF12100 and SCS12050. The AC loss measurement utilised electrical method to obtain overall losses with AC transport currents. The 2D H-formulation by COMSOL Multiphysics has been used to simulate the real geometry and multi-layer HTS tapes. Ferromagnetic AC losses of substrate have been assumed to be ignored as the substrates of SF12100 and SCS12050 are non-magnetic. Hysteresis AC losses in the superconducting layer, and eddy-current AC losses in copper stabilizer, silver overlayer and substrate were concerned in this investigation. The measured AC losses were compared to the AC losses from simulation, with 3 cases of different AC frequency 10, 100, and 1000 Hz. The eddy-current AC losses of copper stabilizer at frequency 1000 Hz were determined from both experiment and simulation. The estimation of AC losses with frequency at 10,000 Hz was also carried out using simulation method. Finally, the frequency dependence of AC losses from Stabilizer-free Tape and Copper Stabilizer Tape were compared and analysed.

  17. Current and future developments in diesel powered hovercraft

    Science.gov (United States)

    Leonard, J. C.; Stevens, M. J.; Buttigieg, J. A.

    After evaluating the development status of the application of diesel power to air-cushion vehicles (ACVs) and surface-effect ships (SESs), attention is given to the AP1-88 ACV, which is both the first and largest operational diesel-powered amphibious craft of this type. An account is given of the ACV and SES features that are dictated by the need to accommodate diesel power sources; the major advantages and disadvantages of diesel (vs gas turbine) engines are discussed. Although cost reductions are achievable against gas turbine powerplant use, lower payload fractions and slightly lower performance capabilities appear to be inescapable.

  18. Large A.C. machines theory and investigation methods of currents and losses in stator and rotor meshes including operation with nonlinear loads

    CERN Document Server

    Boguslawsky, Iliya; Hayakawa, Masashi

    2017-01-01

    In this monograph the authors solve the modern scientific problems connected with A.C. motors and generators, based first on the detailed consideration of their physical phenomena. The authors describe the theory and investigative methods they developed and applied in practice, which are considered to be of essential interest for specialists in the field of the electrical engineering industry in European countries, the USA, Argentina, and Brazil, as well as in such countries as India, China, and Iran. This book will be of interest to engineers specialized in the field of the manufacture, operation, and repair of A.C. machines (motors and generators) as well as electric drives; to professors, lecturers, and post-graduate students of technical universities, who are specializing in the field of electric machine engineering and electric drives; and to students who are engaged in the field of high current techniques, electric drives, and electric machine engineering.

  19. Technology of Zero-Current Breaking of Intelligent AC Contactor%智能交流接触器零电流分断技术

    Institute of Scientific and Technical Information of China (English)

    鲍光海; 张培铭

    2012-01-01

    Zero-current breaking technology is an important content in the research of intelligent AC contactor, In this paper, the optimization calculation aimed to breaking quickly of the electromagnetic mechanism of the intelligent AC contactor is conducted, by using the ANSYS electromagnetic software and the artificial fish swarm optimization algorithm based on genetic algorithm. This method not only ensures the reliable contact process of the intelligent AC contactor, but also realizes a quick release of the executive mechanism, thus greatly reduces the influence to the stability and accuracy of the three-phase contactors, especially the first opening phase when zero-current breaking, which improves the reliability of zero-current breaking and increases the technology research level of the intelligent AC contactor. A prototype is made based on the results of the optimization designation. The testing results show that the breaking time of the intelligent AC contactor is shortened greatly, and the stability of the breaking time is improved significantly too, so the reliability of the zero-current breaking increases significantly.%零电流分断技术是交流接触器智能化研究的重要内容。本文采用Ansys电磁场软件和基于遗传算法的人工鱼群优化算法对智能交流接触器电磁动作机构进行以快速分断为目标的优化计算,不仅保证智能交流接触器可靠与优化的接通过程,而且实现了动作机构快速释放,从而大幅度减小机构分散性对三相触头特别是首开相触头零电流分断准确性与稳定性影响,提高零电流分断的可靠性,从而提高了交流接触器智能化技术的研究水平。根据优化设计结果加工了样机,对样机测试与试验的结果表明,智能交流接触器的分断时间大幅缩短,三相触头分断时间稳定性也得到明显改善,因此零电流分断的可靠性显著提高。

  20. Characterization of a high-power/current pulsed magnetized arc discharge

    NARCIS (Netherlands)

    Zielinski, J. J.; van der Meiden, H. J.; Morgan, T. W.; D.C. Schram,; De Temmerman, G.

    2012-01-01

    A high-power pulsed magnetized arc discharge has been developed to allow the superimposition of a dc plasma and a high-power plasma impulse with a single plasma source. A capacitor bank (8400 mu F) is parallel-coupled to the current regulated power supply. The current is transiently increased from i

  1. Support Vector Machine for Discrimination Between Fault and Magnetizing Inrush Current in Power Transformer

    Directory of Open Access Journals (Sweden)

    V. Malathi

    2007-01-01

    Full Text Available This study presents a novel technique based on Support Vector Machine (SVM for the classification of transient phenomena in power transformer. The SVM is a powerful method for statistical classification of data. The input data to this SVM for training comprises fault current and magnetizing inrush current. SVM classifier produces significant accuracy for classification of transient phenomena in power transformer.

  2. Fundamental Understanding of the Impact High Pulsed Power Loading has on a MicroGrid’s DC or AC Bus

    Science.gov (United States)

    2013-06-12

    Seamless integration of distributed/renewable energy into a smart MicroGrid architecture is a hot topic of research for both public and defense...applications. It is the DoD’s intention to develop a more cost efficient and reliable power architecture on the battlefield. A smart MicroGrid ...dedicated power supplies. The impact this type of loading has on the central DC or AC bus of a MicroGrid must be studied and it was the intent of

  3. Analysis of Input and Output Ripples of PWM AC Choppers

    Directory of Open Access Journals (Sweden)

    Pekik Argo Dahono

    2008-11-01

    Full Text Available This paper presents an analysis of input and output ripples of PWM AC choppers. Expressions of input and output current and voltage ripples of single-phase PWM AC choppers are first derived. The derived expressions are then extended to three-phase PWM AC choppers. As input current and output voltage ripples specification alone cannot be used to determine the unique values of inductance and capacitance of the LC filters, an additional criterion based on the minimum reactive power is proposed. Experimental results are included in this paper to show the validity of the proposed analysis method.

  4. An Improvement on Current Sharing Characteristics of Poloidal Field (PF)-AC-DC Converters%An Improvement on Current Sharing Characteristics of Poloidal Field (PF)-AC-DC Converters

    Institute of Scientific and Technical Information of China (English)

    陈鹏; 傅鹏; 宋执权

    2011-01-01

    In response to the current imbalance phenomenon and its harmfulness, a current sharing circuit model is built up, which reveals the underlying causes for the current imbalance through a quantitative analysis. Then, a feasible approach of improvement, namely enlargement of the length of connection busbars, is proposed. After the amendment, it can be seen that the current sharing coefficient is ahnost unity under rated or fault current conditions.

  5. Transformerless photovoltaic inverters with leakage current and pulsating power elimination

    DEFF Research Database (Denmark)

    Tang, Yi; Yao, Wenli; Wang, H.;

    2015-01-01

    that is inherent in single-phase PV systems. By properly injecting CM voltages to the output filter capacitors, the pulsating power can be decoupled from the dc-link. Therefore, it is possible to use long lifetime film capacitors instead of electrolytic capacitors to improve the reliability of the PV system...

  6. Raptor electrocution on power lines: Current issues and outlook

    Science.gov (United States)

    Lehman, Robert N.

    2001-01-01

    Electrocution on power lines is one of many human-caused mortality factors that affect raptors. Cost-effective and relatively simple raptor-safe standards for power line modification and construction have been available for over 25 years. During the 1970s and early 1980s, electric industry efforts to reduce raptor electrocutions were very coordinated and proactive, but predictions about resolving the problem were overly optimistic. Today, raptors continue to be electrocuted, possibly in large numbers. The electrocution problem has not been resolved, partly because of the sheer number of potentially lethal power poles in use and partly because electrocution risks may be more pervasive and sometimes less conspicuous than once believed. Also, responses to the problem by individual utilities have not been uniform, and deregulation of the electric industry during the 1990s may have deflected attention from electrocution issues. To control raptor electrocutions in the future, the industry must increase information sharing and technology transfer, increase efforts to retrofit lethal power poles, and above all ensure that every new and replacement line constructed incorporates raptor-safe standards at all phases of development. Finally, responsibility for the electrocution problem must be shared. Federal, state, and local governments, academic institutions, the conservation community, and the consumer all can play critical roles in an effort that will, by necessity, extend well into the new century.

  7. A NEW METHOD TO CALCULATE COMPENSATION CURRENT IN PARALLEL ACTIVE POWER FILTER

    Directory of Open Access Journals (Sweden)

    Ahmet ALTINTAŞ

    2004-03-01

    Full Text Available Nowadays, active power filter plays an important role in reducing harmonic current and reactive power in power lines. The reliability and effectiveness of an active power filter depends basically on three characteristics. These are the modulation method, the design characteristics of the PWM modulator and the method implemented to generate compensation current. For the last one, there are many proposed methods. Most of them complicated and hence difficult to implement and adjust. In this study, a new method to calculate compensation current is improved and tested in single-phase parallel active power filter controlled by microcontroller. Experimental and simulation results are presented in the paper.

  8. Influence of metallic trays on the ac resistance and ampacity of low-voltage cables under non-sinusoidal currents

    Energy Technology Data Exchange (ETDEWEB)

    Demoulias, Charis; Labridis, Dimitris P.; Dokopoulos, Petros; Gouramanis, Kostas [Aristotle University of Thessaloniki, Department of Electrical and Computer Engineering, Thessaloniki (Greece)

    2008-05-15

    This paper investigates the influence of metallic trays on the ac resistance of PVC insulated, low-voltage (0.6/1.0 kV) cables made according to CENELEC standard HD603. The investigation is made with a validated finite element model for the fundamental and higher harmonic frequencies. It is shown that the cable's effective resistance is affected significantly by the relative magnetic permeability and specific conductivity of the tray, while the tray's dimensions do not affect it. The orientation of the cable with respect to the tray also influences the ac resistance of the phase and neutral conductors. An ampacity derating factor is defined and calculated for various cable cross-sections and harmonic loads. The presence of a metallic tray is shown to cause an additional derating of cable's ampacity which is relatively significant at large cable cross-sections. Working examples demonstrate the application of the results in calculating the ampacity of low-voltage cables and in assessing the energy savings that will result from the use of active harmonic filters. (author)

  9. Design of the power supply system for the plasma current modulation on J-TEXT tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, M.; Shao, J.; Ma, S.X., E-mail: mashaoxiang@hust.edu.cn; Liang, X.; Yu, K.X.; Pan, Y.

    2016-10-15

    Highlights: • A modification scheme of heating field power supply system for plasma current modulation. • High-power fast control power supply with multilevel cascade circuit. • Restraining circulating current with coupled inductors in cyclic symmetric structure. - Abstract: In order to further study the influence of current modulation parameters on suppressing tearing instability, the plasma current should be modulated in a wider range. So a modification scheme is designed to improve the performance of ohmic heating power supply system on J-TEXT tokamak. A multilevel cascade circuit with carrier phase-shifted PWM technique has been proposed. Coupled inductors are connected in the form of cyclic symmetry to restrain the circulating current caused by multiple paralleled branches. The simulation proves this proposed current modulation power supply system matches output requirement and achieves good current sharing effect. Finally, a prototype is designed, and the experiment results can verify the correctness of the simulation model well.

  10. A Circulating-Current Suppression Method for Parallel Connected Voltage Source Inverters (VSI) with Common DC and AC Buses

    DEFF Research Database (Denmark)

    Wei, Baoze; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2017-01-01

    applications. The basic concept of the proposed circulating-current suppression method is to modify the original current references by using the current difference among the parallel inverters. In the proposed approach, both of cross circulating-current and zero-sequence circulating-current are considered...... on the virtual impedance. Further, a circulating-current control loop is added to improve the average current-sharing performance among parallel VSIs. Experimental results are presented to show the effectiveness of the proposed control method to suppress both of the cross and zero-sequence circulating-currents....

  11. Study of eddy current power loss in an RCS vacuum chamber

    Institute of Scientific and Technical Information of China (English)

    XU Shou-Yan; WANG Sheng

    2012-01-01

    In a Rapid Cycling Synchrotron (RCS),power loss due to an eddy current on the metal vacuum chamber would cause heating of the vacuum chamber.It is important to study the effect for estimating eddy current induced power loss and temperature growth.Analytical formulas for eddy current power loss for various types of vacuum chambers are derived for dipole and quadrupole repectively.By using the prototype of dipole of CSNS/RCS,an experiment was done to test the analytical formula.The derived formulas were applied to calculating the eddy current power loss on some special structures of an RCS vacuum chamber.

  12. Current Leakage Evolution in Partially Gate Raptured Power MOSFETs

    Science.gov (United States)

    Scheick, Leif; Edmonds, Larry; Selva, Luis; Chen, Yuan

    2008-01-01

    It has been observed that power MOSFETs can experience an SEGR and continue to function with altered parameters. We propose that there are three different types of SEGR modes; the micro-break, the thermal runaway, and the avalanche breakdown. Data that demonstrates these stages of device failure are presented as well as a proposed model for the micro-break. Brief discussions of the other modes, based on analysis combined with our interpretations of the older literature, are also given.

  13. High Average Current Electron Guns for High-Power FELs

    Science.gov (United States)

    2009-12-09

    FELs 10 Appendix B: Thermionic Injectors 11 Appendix C: Grid Fields and Bunch Emittance 13 Appendix D: PARMELA Simulation of an IOT Gun 16...Inductive Output Tube ( IOT ) amplifiers [32-34] and can generate average currents of ~1 A, peak currents of ~ 5-10 A, cathode-anode voltages of ~ 35...of grid wires, centered at z = zG and x = ±a, ±3a, ±5a, ..., is given by <D(JC,Z) = - X n = ±l.±3. Fa(x,z) Gn(x,z) ( C3 ) where *0 = (1 / 2

  14. Basic Characteristics of New Developed Higher-Voltage Direct-Current Power-Feeding Prototype System

    Science.gov (United States)

    Babasaki, Tadatoshi; Tanaka, Toshimitsu; Tanaka, Toru; Nozaki, Yousuke; Aoki, Tadahito; Kurokawa, Fujio

    High efficiency power feeding systems are effective solutions for reducing the ICT power consumption with reducing power consumption of the ICT equipment and cooling systems. A higher voltage direct current (HVDC) power feeding system prototype was produced. This system is composed of a rectifier equipment, power distribution unit, batteries, and the ICT equipment. The configuration is similar to a -48V DC power supply system. The output of the rectifier equipment is 100kW, and the output voltage is 401.4V. This paper present the configuration of the HVDC power feeding system and discuss its basic characteristics in the prototype system.

  15. Power Line Communication (PLC) in Space - Current Status and Outlook

    Science.gov (United States)

    Wolf, J.

    2012-05-01

    The Power Line Communication (PLC) technology as known from various terrestrial applications, e.g. in building automation, in the automotive sector and on aircraft, appears to be a promising technology for the use on spacecraft. Starting from a critical overview on existing terrestrial PLC applications with their pros and cons, the paper gives a motivation for the introduction of the PLC technology on spacecraft, discusses the potential areas where it can be applied and is highlighting the potential problem areas. A short overview of on-going ESA PLC activities is provided and an outlook is given.

  16. Power Quality Improvement And Mitigation Of Voltage Sag And Current Swell Using Distributed Power Flow Controller

    Directory of Open Access Journals (Sweden)

    P.NIRMALA

    2014-09-01

    Full Text Available Modern power utilities have to respond to a number of challenges such as growth of electricity demand specially in non-linear loads in power grids, consequently, That higher power quality should be considered. In this paper, DPFC which is similar to unified power flow controller (UPFC in structure, which is used to mitigate the voltage sag and swell as a power quality issue. Unlike UPFC, the common dc-link in DPFC, between the shunt and series converter devices should be eliminated and three-phase series converter is divided to several single-phase series distributed converters through the power transmission line. And also to detect the voltage sags and find out the three single-phase reference voltages of DPFC, the synchronous reference frame method is proposed. Application of DPFC in power quality enhancement is simulated in Mat lab/Simulink environment which show the effectiveness of the proposed structure

  17. DSPIC BASED POWER ASSISTED STEERING USING BRUSHLESS DIRECT CURRENT MOTOR

    Directory of Open Access Journals (Sweden)

    G. R.P. Lakshmi

    2013-01-01

    Full Text Available This study illustrates the Electrically Assisted power Steering (EAS using BLDC motor for a vehicle. Earlier the Electrically Assisted power Steering (EAS was implemented with DSP. This study shows the usage of a dsPIC to control the BLDC motor with an encoder. The BLDC motor here is driven by dsPIC through a three phase inverter system. IRAMS type of inverter is used which is cost efficient and space efficient. The dsPIC supplied with the input of the steering. In its higher capacity the vehicles speed controller acts as the assistance level controller for steering effort. At the lower capacity, the torque controller gives the effort level control. In reality this can be realized as torque sensor and vehicle sensor interfaced in the dsPIC. For actual implementation in the system, a dsPIC-based BLDC motor controller with three-phase inverter module is used with Hall-effect sensor feedback. It is designed in such a way that the driver assistance can be varied at any time without any difficulty.

  18. A Circulating Current Suppression Method for Parallel Connected Voltage-Source-Inverters (VSI) with Common DC and AC Buses

    DEFF Research Database (Denmark)

    Wei, Baoze; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2016-01-01

    on circulating current control loops used to modify the reference currents by compensating the error currents among parallel inverters. Both of the cross and zero-sequence circulating currents are considered. The proposed method is coordinated together with droop and virtual impedance control. In this paper...... loop is added to acquire a better average current sharing performance among parallel VSIs, which can effectively suppress both of the cross and zero-sequence circulating currents. Experimental results are presented in order to verify the effectiveness of the proposed control strategy....

  19. Development of a low cost integrated 15 kW A.C. solar tracking sub-array for grid connected PV power system applications

    Science.gov (United States)

    Stern, M.; West, R.; Fourer, G.; Whalen, W.; Van Loo, M.; Duran, G.

    1997-02-01

    Utility Power Group has achieved a significant reduction in the installed cost of grid-connected PV systems. The two part technical approach focused on 1) The utilization of a large area factory assembled PV panel, and 2) The integration and packaging of all sub-array power conversion and control functions within a single factory produced enclosure. Eight engineering prototype 15kW ac single axis solar tracking sub-arrays were designed, fabricated, and installed at the Sacramento Municipal Utility District's Hedge Substation site in 1996 and are being evaluated for performance and reliability. A number of design enhancements will be implemented in 1997 and demonstrated by the field deployment and operation of over twenty advanced sub-array PV power systems.

  20. Enhanced low current, voltage, and power dissipation measurements via Arduino Uno microcontroller with modified commercially available sensors

    Science.gov (United States)

    Tanner, Meghan; Eckel, Ryan; Senevirathne, Indrajith

    The versatility, simplicity, and robustness of Arduino microcontroller architecture have won a huge following with increasingly serious engineering and physical science applications. Arduino microcontroller environment coupled with commercially available sensors have been used to systematically measure, record, and analyze low currents, low voltages and corresponding dissipated power for assessing secondary physical properties in a diverse array of engineering systems. Setup was assembled via breadboard, wire, and simple soldering with an Arduino Uno with ATmega328P microcontroller connected to a PC. The microcontroller was programmed with Arduino Software while the bootloader was used to upload the code. Commercial Hall effect current sensor modules ACS712 and INA169 current shunt monitor was used to measure corresponding low to ultra-low currents and voltages. Stable measurement data was obtained via sensors and compared with corresponding oscilloscope measurements to assess reliability and uncertainty. Sensor breakout boards were modified to enhance the sensitivity of the measurements and to expand the applicability. Discussion of these measurements will focus on capabilities, capacities and limitations of the systems with examples of possible applications. Lock Haven Nanotechnology Program.

  1. Power sharing algorithm for vector controlled six-phase AC motor with four customary three-phase voltage source inverter drive

    DEFF Research Database (Denmark)

    Padmanaban, Sanjeevikumar; Grandi, Gabriele; Blaabjerg, Frede

    2015-01-01

    This paper considered a six-phase (asymmetrical) induction motor, kept 30 phase displacement between two set of three-phase open-end stator windings configuration. The drive system consists of four classical three-phase voltage inverters (VSIs) and all four dc sources are deliberately kept isolated......) by nearest three vectors (NTVs) approach is adopted to regulate each couple of VSIs. The proposed power sharing algorithm is verified by complete numerical simulation modeling (Matlab/ Simulink-PLECS software) of whole ac drive system by observing the dynamic behaviors in different designed condition. Set...

  2. Current and Future Opportunities for Wind Power in the Southeast

    Energy Technology Data Exchange (ETDEWEB)

    Tinnesand, Heidi; Roberts, Owen; Lantz, Eric

    2016-10-05

    This presentation discusses future wind opportunities in the Southeast including factors such as changes in wind turbine technology, historical innovation trends, and forecast demand growth among regions. The presentation covers the current status of wind in the United States at 80-m hub height and the near-future outlook with a hub height at 110 to 140 meters. Future cost reductions in 2030 and beyond are also explored. Heidi Tinnesand presented this information to a utility advisory group meeting in Charlotte, North Carolina, on October 5, 2016.

  3. Comprehensive Investigation on Current Imbalance among Parallel Chips inside MW-Scale IGBT Power Modules

    DEFF Research Database (Denmark)

    Wu, Rui; Smirnova, Liudmila; Wang, Huai

    2015-01-01

    With the demands for increasing the power rating and improving reliability level of the high power IGBT modules, there are further needs of understanding how to achieve stable paralleling and identical current sharing between the chips. This paper investigates the stray parameters imbalance among...... parallel chips inside the 1.7 kV/1 kA high power IGBT modules at different frequencies by Ansys Q3D parastics extractor. The resulted current imbalance is further confirmed by experimental measurement....

  4. Synchronous Study of Ferroresonance and Inrush Current Phenomena and their Related Reasons in Ground Power Networks

    Science.gov (United States)

    Akrami, Amin; Ghaderi, Mohammad; Ghadi, Saeed

    2010-01-01

    Energizing the power transformers usually results in flowing very high inrush currents. This harmful current can be minimized using controlled switching and considering the value of residual flux. But nowadays, developing the ground power networks results in high increment of ferroresonance phenomenon occurrence due to the line' capacitance reactance and nonlinear inductive reactance of power transformer's core. In this study, these transient phenomena and their cause have studied synchronously.

  5. Stability analysis of direct current control in current source rectifier

    DEFF Research Database (Denmark)

    Lu, Dapeng; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    Current source rectifier with high switching frequency has a great potential for improving the power efficiency and power density in ac-dc power conversion. This paper analyzes the stability of direct current control based on the time delay effect. Small signal model including dynamic behaviors...... of dc link is developed to identify the control plants of grid ac current control and dc current control. Analysis on the poles and zeros under dq frame is carried out. Base on this model, it turns out that the phase lag caused by the time delay can stabilized the grid ac current control while reduces...... the stable region for dc current control. Simulation and experimental results are presented to validate the theoretical analysis....

  6. POLITICAL POWER IN THE PRISM OF POLITICAL ANALYSIS (EXPERIENCE REVIEW OF CURRENT RESEARCH DIRECTIONS

    Directory of Open Access Journals (Sweden)

    A. N. Kuryukin

    2010-01-01

    Full Text Available The broad theoretical material considered relevant areas of the study of political power. Reveals the patterns of occurrence and development of a strictly scientific views on political power as a phenomenon and a social process. Determined the current trends of development of theoreticalunderstanding of political power in relation to the stages of its evolution. The most urgent technological model of exercising political power.

  7. Calculation of Skin Depths and Eddy-Current Power Losses for Magnetic Position Sensors

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    We present a theoretic model to calculate skin depths and eddy-current power losses for a magnetic position sensor. Eddy-current, arised from the operation of an alternating-current ex citation, induces secondary currents and fields between magnetic material and magnetic position sensor. In this paper, a magnetic position sensor system is simplified to be an outer-winding coil along the axial direction of a low carbon steel bar. The analytical model is derived from basic field and circuit theory considering a linear approximation for a nonlinear permeability. Thus the skin depths and eddy-current power losses from the model in eddy-current modeling techniques at various frequencies of an excited current source can be calculated. The proposed configuration is capable of predicting the skin depths and eddy-current power losses for a magnetic position sensor and has a consistence with experiments.

  8. Evaluation of levels of defect sites present in highly ordered pyrolytic graphite electrodes using capacitive and faradaic current components derived simultaneously from large-amplitude Fourier transformed ac voltammetric experiments.

    Science.gov (United States)

    Lee, Chong-Yong; Bond, Alan M

    2009-01-15

    The level of edge plane defect sites present in highly ordered pyrolytic graphite (HOPG) electrodes has been evaluated via analysis of dc, ac fundamental, and higher-order ac harmonics available from a single large-amplitude Fourier transformed (FT) ac voltammetric experiment. Deliberate introduction of a low level of edge plane defect was achieved by polishing, with a higher level being introduced via electrochemical pretreatment. Kinetics regimes associated with fast electron transfer on the edge plane defect sites and slow electron transfer on the basal plane surface are resolved under ac conditions when using the surface-sensitive [Fe(CN)(6)](3-/4-) redox probe. However, because of their insensitivity to slow electron transfer, higher-order ac faradaic harmonics almost exclusively detect only the much faster processes that emanate from edge plane defect sites. Thus, detection of fourth- and higher-order ac Faradaic harmonic components that are devoid of background capacitive current is possible at freshly cleaved HOPG in the region near the reversible potential for the [Fe(CN)(6)](3-/4-) process. Under these circumstances, dc cyclic voltammograms exhibit only reduction and oxidation peaks separated by more than 1 V. The fundamental ac harmonic provides detailed information on the capacitive current, which increases with the level of edge plane defect sites. Apparent charge transfer rate constants also can be derived from peak-to-peak separations obtained from the dc aperiodic component. Estimates of the percentage of edge plane defect sites based on ac higher harmonics, capacitance, and dc aperiodic component that are available from a single experiment have been compared. The edge plane defect levels deduced from capacitance (fundamental harmonic ac component) and higher harmonic Faradaic currents are considered to be more reliable than estimations based on apparent rate constants derived from the dc aperiodic component or conventional dc cyclic voltammogram.

  9. Currents, magnetization and AC-losses of YBa 2Cu 3O 7 superconductors in rapidly changing magnetic fields

    Science.gov (United States)

    Kwasnitza, K.; Plotzner, V.; Waldmann, M.; Widmer, E.

    1988-06-01

    In YBa 2Cu 3O 7 samples of different shape time dependent magnetization currents were induced at 4.2K by the application of rapid magnetic field changes. This contactless method allows the study of the intergrain and intragrain currents in the resistive flux flow state.

  10. Silver eel migration, wind power and alternating current fields; Blankaalsvandring, vindkraft och vaexelstroemsfaelt, 2011

    Energy Technology Data Exchange (ETDEWEB)

    Lagenfelt, Ingvar; Andersson, Ingemar; Westerberg, Haakan

    2012-02-15

    How are eels affected by large offshore wind farms? The study follows the silver eels' migration and behavior at Lillgrund wind farm in Oeresund and the passage over an 130 kV AC cable between the mainland and Oeland. The aim is to see if the AC cable precludes or otherwise affects the eel's ability to reach its destination. Eels migrate up to 7500 km from the Baltic Sea to spawn in the Sargasso Sea. Every delay is of importance for the silver eels, which must be able to travel the entire distance on a single energy reserve. Fish, which make use of the earth's magnetic field for navigation or which are sensitive to electromagnetic fields, may be affected by AC cables on the seabed. The study shows that the silver eels swimming speed was reduced when there was more current in the cable and there was an average delay of 40 minutes before they passed it

  11. Piezoelectric two-dimensional nanosheets/anionic layer heterojunction for efficient direct current power generation

    Science.gov (United States)

    Kim, Kwon-Ho; Kumar, Brijesh; Lee, Keun Young; Park, Hyun-Kyu; Lee, Ju-Hyuck; Lee, Hyun Hwi; Jun, Hoin; Lee, Dongyun; Kim, Sang-Woo

    2013-06-01

    Direct current (DC) piezoelectric power generator is promising for the miniaturization of a power package and self-powering of nanorobots and body-implanted devices. Hence, we report the first use of two-dimensional (2D) zinc oxide (ZnO) nanostructure and an anionic nanoclay layer to generate piezoelectric DC output power. The device, made from 2D nanosheets and an anionic nanoclay layer heterojunction, has potential to be the smallest size power package, and could be used to charge wireless nano/micro scale systems without the use of rectifier circuits to convert alternating current into DC to store the generated power. The combined effect of buckling behaviour of the ZnO nanosheets, a self-formed anionic nanoclay layer, and coupled semiconducting and piezoelectric properties of ZnO nanosheets contributes to efficient DC power generation. The networked ZnO nanosheets proved to be structurally stable under huge external mechanical loads.

  12. Piezoelectric two-dimensional nanosheets/anionic layer heterojunction for efficient direct current power generation.

    Science.gov (United States)

    Kim, Kwon-Ho; Kumar, Brijesh; Lee, Keun Young; Park, Hyun-Kyu; Lee, Ju-Hyuck; Lee, Hyun Hwi; Jun, Hoin; Lee, Dongyun; Kim, Sang-Woo

    2013-01-01

    Direct current (DC) piezoelectric power generator is promising for the miniaturization of a power package and self-powering of nanorobots and body-implanted devices. Hence, we report the first use of two-dimensional (2D) zinc oxide (ZnO) nanostructure and an anionic nanoclay layer to generate piezoelectric DC output power. The device, made from 2D nanosheets and an anionic nanoclay layer heterojunction, has potential to be the smallest size power package, and could be used to charge wireless nano/micro scale systems without the use of rectifier circuits to convert alternating current into DC to store the generated power. The combined effect of buckling behaviour of the ZnO nanosheets, a self-formed anionic nanoclay layer, and coupled semiconducting and piezoelectric properties of ZnO nanosheets contributes to efficient DC power generation. The networked ZnO nanosheets proved to be structurally stable under huge external mechanical loads.

  13. HVDC交流滤波器合闸的涌流研究%Simulation of Inrush Current at HVDC AC Filter Switching on

    Institute of Scientific and Technical Information of China (English)

    丛宝丰; 夏成军; 席亮

    2013-01-01

    HVDC系统交流滤波器的投入会产生较大涌流,会造成滤波器损坏,保护误动作,威胁系统安全.针对上述问题,采用了基于蒙特卡洛算法与自定义建模的仿真研究,对逆变侧滤波器涌流与表征三相电流不平衡性的零序电流进行了详细的计算,基于计算结果,提出加装POW装置与临时闭锁不平衡保护等抑制涌流影响的方法.%In HVDC system,the AC filter will produce larger inrush current during switching, which will cause damage to the filters, protection misoperation and threat to DC system security. To solve the problem, a simulation based on Monte Carlo algorithm and PSCAD user-definition model has been come up with. Make a lot of simulations about inrush current and the zero sequence current which stands for three-phase unbalanced inrush current at the inverter side. Based on these results, some methods which solve the effect of inrush current has been come up with, like erecting POW, locking the unbalanced protection temporarily.

  14. Construction and evaluation of photovoltaic power generation and power storage system using SiC field-effect transistor inverter

    Energy Technology Data Exchange (ETDEWEB)

    Oku, Takeo, E-mail: oku@mat.usp.ac.jp; Matsumoto, Taisuke; Ohishi, Yuya [Department of Materials Science, The University of Shiga Prefecture, 2500 Hassaka, Hikone, Shiga 522-8533 (Japan); Hiramatsu, Koichi; Yasuda, Masashi [Collaborative Research Center, The University of Shiga Prefecture, 2500 Hassaka, Hikone, Shiga 522-8533 (Japan); Shimono, Akio; Takeda, Yoshikazu [Kyoshin Electric Co. Ltd., 18, Goshonouchi-Nishimachi, Shichijo, Shimogyou-ku, Kyoto 600-8865 (Japan); Murozono, Mikio [Clean Venture 21 Co., 38 Ishihara Douno-Ushirocho, Kissyouin, Minami-ku, Kyoto 601-8355 (Japan)

    2016-02-01

    A power storage system using spherical silicon (Si) solar cells, maximum power point tracking charge controller, lithium-ion battery and a direct current-alternating current (DC-AC) inverter was constructed. Performance evaluation of the DC-AC inverter was carried out, and the DC-AC conversion efficiencies of the SiC field-effect transistor (FET) inverter was improved compared with those of the ordinary Si-FET based inverter.

  15. 一种高功率因数交流 LED 驱动电路的设计%Design of AC LED Driver Circuit with High Power Factor

    Institute of Scientific and Technical Information of China (English)

    刘生建; 马桂芳; 邱晓芬

    2016-01-01

    传统的LED驱动电路由于采用AC-DC变换器,需要大的电感和电解电容,导致LED驱动电路存在体积大、成本高、寿命短等问题,提出一种新型交流电压直接驱动的LED驱动电路。该驱动电路仅需要MOSFETs和运放等有源器件,输入电流能跟随输入电压呈正弦波形变换,以获得高功率因数和低THD。仿真和实验验证该驱动电路的电气特性。%Conventional LED drivers consist of AC -DC converters which require passive components such as high value inductors and electrolytic capacitors for their operation ,the use of such components increases the size and cost of the LED system while de-creasing the overall life time , a novel driver circuit that can directly run from AC voltage is presented .The proposed driver circuit only needs active devices like MOSFETs and op -amps for power processing ,the input current is selectively controlled to follow a sinusoidal waveform to achieve low harmonic distortion and high power factor .The efficiency of the proposed system is around 80%for a 1.5W converter with 8% total harmonic distortion and 0.97 power factor,both simulation and experimental results have been presented to verify the operation of the proposed circuit .

  16. Analysis and Comparing of Urban Rail Locomotive Auxiliary System AC Power Supply Mode%城轨列车辅助系统交流供电方式的分析与比较

    Institute of Scientific and Technical Information of China (English)

    阎纯洁

    2015-01-01

    Through analyzing the urban rail locomotive auxiliary system AC power system supply mode, comparing the ad-vantages and disadvantages of general power supply mode and individual supply mode, prove accordance to urban rail auxil-iary system AC power supply mode selection.%通过对城轨列车辅助系统交流供电方式进行分析,比较集中供电方式和分散供电方式的各自优劣,为城轨列车辅助系统交流供电供电方式选型提供依据。

  17. Dynamic modelling and robust current control of wind-turbine driven DFIG during external AC voltage dip

    Institute of Scientific and Technical Information of China (English)

    HU Jia-bing; HE Yi-kang

    2006-01-01

    Doubly-FedInduction Generator (DFIG), with vector control applied, is widely used in Variable-Speed ConstantFrequency (VSCF) windenergy generation system and shows good performance in maximum wind energy capture. But in two traditional vector control schemes, the equivalent stator magnetizing current is considered invariant in order to simplify the rotor current inner-loop controller. The two schemes can perform very well when the grid is in normal condition. However, when grid disturbance such as grid voltage dip or swell fault occurs, the control performance worsens, the rotor over current occurs and the Fault Ride-Through (FRT) capability of the DFIG wind energy generation system gets seriously deteriorated. An accurate DFIG model was used to deeply investigate the deficiency of the traditional vector control. The improved control schemes of two typical traditional vector control schemes used in DFIG were proposed, and simulation study of the proposed and traditional control schemes, with robust rotor current control using Internal Model Control (IMC) method, was carried out. The validity of the proposed modified schemes to control the rotor current and to improve the FRT capability of the DFIG wind energy generation system was proved by the comparison study.

  18. A Novel High Performance Bridgeless Ac-Dc Boost Converter

    Directory of Open Access Journals (Sweden)

    S.M.AshrafulAlam Mohon

    2016-08-01

    Full Text Available A new single phase high performance bridgeless AC-DC Boost converter is proposed. The converter is made bridgeless by the use of two unidirectional switches and two diodes at the input ac side for power conversion for both positive and negative half cycle. Because of the high frequency switching, the power factor of the circuit is inherently corrected and it requires a small filter to make the input current near sinusoidal with limited THD. The significant improvement in THD makes the circuit a good choice in applications needing AC-DC conversion with power conditioning. The circuit exhibits such better performances than conventional AC-DC boost converter with variable loads at constant frequency switching with no additional control circuits. The efficiency of the circuit is also satisfactory. Analysis and simulation results of the circuit are obtained by using software simulation. The main advantage of this new AC-DC converter is its superior power quality over conventional AC-DC boost converter

  19. A zero-voltage switching technique for minimizing the current-source power of implanted stimulators.

    Science.gov (United States)

    Çilingiroğlu, Uğur; İpek, Sercan

    2013-08-01

    The current-source power of an implanted stimulator is reduced almost to the theoretical minimum by driving the electrodes directly from the secondary port of the inductive link with a dedicated zero-voltage switching power supply. A feedback loop confined to the secondary of the inductive link adjusts the timing and conduction angle of switching to provide just the right amount of supply voltage needed for keeping the current-source voltage constant at or slightly above the compliance limit. Since drive is based on current rather than voltage, and supply-voltage update is near real-time, the quality of the current pulses is high regardless of how the electrode impedance evolves during stimulation. By scaling the switching frequency according to power demand, the technique further improves overall power consumption of the stimulator. The technique is implemented with a very simple control circuitry comprising a comparator, a Schmitt trigger and a logic gate of seven devices in addition to an on-chip switch and an off-chip capacitor. The power consumed by the proposed supply circuit itself is no larger than what the linear regulator of a conventional supply typically consumes for the same stimulation current. Still, the sum of supply and current-source power is typically between 20% and 75% of the conventional source power alone. Functionality of the proposed driver is verified experimentally on a proof-of-concept prototype built with 3.3 V devices in a 0.18 μm CMOS technology.

  20. Time-resolved magneto-optical imaging of Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} thin films in high-frequency AC current regime

    Energy Technology Data Exchange (ETDEWEB)

    Lucarelli, A [Department of Applied Science, College of William and Mary, Williamsburg, VA 23187-8795 (United States); Luepke, G [Department of Applied Science, College of William and Mary, Williamsburg, VA 23187-8795 (United States); Haugan, T J [Air Force Research Laboratory, Wright-Patterson AFB, OH 45433-7919 (United States); Levin, G A [Air Force Research Laboratory, Wright-Patterson AFB, OH 45433-7919 (United States); Barnes, P N [Air Force Research Laboratory, Wright-Patterson AFB, OH 45433-7919 (United States)

    2006-06-15

    We present a time-resolved magneto-optical (MO) imaging study of high-temperature superconductor (HTS) in a high-frequency alternating current (AC) regime. The evolution of the magnetic flux density distribution in YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) thin film samples is studied as a function of the phase of the applied AC current. A quantitative analysis of the data shows that the maxima of the AC current density is shifted from the edges further inside the sample, which may be caused by the higher self-induced field in that region. This technique can be used to study magnetic flux evolution in HTS films and coated conductors in the high-frequency current regime.

  1. Effective Leadership and Management of an ACS Injury Prevention Program: Current Opinions and Perspectives From Where the Rubber Meets the Road.

    Science.gov (United States)

    Wolfe, Elizabeth S; Bryant, Elizabeth A

    The American College of Surgeons (ACS) mandates that each verified trauma center must have an injury prevention coordinator (IPC); however, Chapter 18 in the Resources for Optimal Care of the Injured Patient (2014) provides minimal information on how to effectively lead or manage an injury prevention (IP) program. This opinion article addresses 3 fundamental components of an effective IP program: (1) construction of an innovative vision of IP programming using current technology; (2) intentional investment and involvement; and (3) stakeholder leadership, engagement, and sustainability. This article also provides leadership and management methods from other professions both within and outside of the health care field that can be translated into sustainable IP program planning, implementation, and longevity.

  2. Critical current densities of Sr0.6K0.4Fe2As2 superconductors estimated from AC susceptibilities

    Science.gov (United States)

    Setoyama, Subaru; Kinoshita, Junichi; Akune, Tadahiro; Sakamoto, Nobuyoshi; Murakami, Kouji; Yoshida, Nobuyuki; Kiuchi, Masaru; Otabe, Edmund Soji; Matsushita, Teruo; Ge, Jun; Ni, Baorong; Wang, Lei; Qi, Yanpeng; Zhang, Xianping; Gao, Zhaoshun; Ma, Yanwei

    2013-01-01

    AC susceptibilities (real χ‧ and imaginary χ″) of Sr0.6K0.4Fe2As2 (122 type) polycrystalline with Ag addition are analysed by the grained Bean model. A variety of characteristics, double peak in χ″ and shoulder transition in χ‧, appear in the model simulation. Comparing the measured χ‧ and χ″ with the model allows more clear insight on the polycrystalline structure. Estimated critical current densities Jcg and Jcℓ of the grain and the link in the iron-based pnictides show that the addition of 20 wt.% Ag increases Jcℓ 9 times larger. Improvement of intergrain characteristics with Ag addition is clearly indicated.

  3. The NC Power Supply Design of Large Current and Wide Frequency Pulse in SEAM

    Directory of Open Access Journals (Sweden)

    Jianping Zhou

    2013-07-01

    Full Text Available There are a lot of ways to achieve large current pulse power supply, and the more common way is to adopt the inverter switching circuit to achieve pulse power supply. The core of the NC power supply design of large current and wide frequency pulse in SEAM is using two-stage modulation. Combined with inverter technology, DC chopper technology and NC technology, it not only can achieve the adjustability of the output pulse amplitude, but also can realize continuous adjustment of the output pulses and the duty cycle. The front stage of power supply uses DC/DC transformation circuit with the UC3879 integrated control chip as the core. With the microcontroller as the control core, the backward stage uses DC chopper circuit to achieve the NC power supply of multi-parameter adjustable output large current pulse.

  4. A comparative study of modelling AC electric arc by one-dimensional interpolation for power system harmonics analysis

    OpenAIRE

    Liu Yu-Jen; Hung Jen-Pan; Chen Shang-I; Lin Cheng-Wei

    2016-01-01

    Electric arc is a discharge phenomenon caused by particular electrical events and arc produced facilities in power system, for example the occurrence of short-circuit fault in feeders and the use of electric arc furnace for steel-making. All of these electric arcs have a highly nonlinear nature and can be considered as a significant source of power quality problems. To investigate the impacts of the electric arcs on power quality studies the development of the electric arc models for simulati...

  5. Negative sequence current control in wind power plants with VSC-HVDC connection

    DEFF Research Database (Denmark)

    Chaudhary, Sanjay; Teodorescu, Remus; Rodriguez, Pedro;

    2012-01-01

    Large offshore wind power plants may have multi-MW wind turbine generators (WTG) equipped with full-scale converters (FSC) and voltage source converter (VSC) based high voltaage direct-current (HVDC) transmission for grid connection. The power electronic converters in theWTG-FSC and the VSC-HVDC...... allow fast current control in the offshore grid. This paper presents a method of controlling the negative sequence current injection into the offshore grid from the VSC-HVDC as well as WTG-FSCs. This would minimize the power oscillations and hence reduce the dc voltage overshoots in the VSC-HVDC system...... sequence current control mitigates the power oscillations and therefore limits the dc voltage excursions in the VSC-HVDC system during the asymmetric faults....

  6. Performance of current measurement system in poloidal field power supply for Experimental Advanced Superconducting Tokamak

    Science.gov (United States)

    Liu, D. M.; Li, J.; Wan, B. N.; Lu, Z.; Wang, L. S.; Jiang, L.; Lu, C. H.; Huang, J.

    2016-11-01

    As one of the core subsystems of the Experimental Advanced Superconducting Tokamak (EAST), the poloidal field power system supplies energy to EAST's superconducting coils. To measure the converter current in the poloidal field power system, a current measurement system has been designed. The proposed measurement system is composed of a Rogowski coil and a newly designed integrator. The results of the resistor-inductor-capacitor discharge test and the converter equal current test show that the current measurement system provides good reliability and stability, and the maximum error of the proposed system is less than 1%.

  7. Current Sharing inside a High Power IGBT Module at the Negative Temperature Coefficient Operating Region

    CERN Document Server

    Asimakopoulos, Panagiotis; Bongiorno, M; Thiringer, T

    2016-01-01

    This work investigates the current sharing effect of a high power Soft Punch Through IGBT module in the Negative Temperature Coefficient region. The unbalanced current sharing between two of the substrates is demonstrated for different current and temperature levels and its impact on the thermal stressing of the device is evaluated. The results indicate that the current asymmetry does not lead to a significant thermal stressing unbalance between the substrates.

  8. Active and reactive power control of a current-source PWM-rectifier using space vectors

    Energy Technology Data Exchange (ETDEWEB)

    Salo, M.; Tuusa, H. [Tampere University of Technology (Finland). Department of Electrical Engineering, Power Electronics

    1997-12-31

    In this paper the current-source PWM-rectifier with active and reactive power control is presented. The control system is realized using space vector methods. Also, compensation of the reactive power drawn by the line filter is discussed. Some simulation results are shown. (orig.) 8 refs.

  9. A High-Efficiency 4x45W Car Audio Power Amplifier using Load Current Sharing

    NARCIS (Netherlands)

    Mensink, C.H.J.; Mensink, C.; van Tuijl, Adrianus Johannes Maria; Gierkink, Sander L.J.; Mostert, F.; van der Zee, Ronan A.R.

    2010-01-01

    A 4x45W (EIAJ) monolithic car audio power amplifier is presented that achieves a power dissipation decrease of nearly 2x over standard class AB operation by sharing load currents between loudspeakers. Output signals are conditioned using a common-mode control loop to allow switch placement between l

  10. A High-Efficiency 4x45W Car Audio Power Amplifier using Load Current Sharing

    NARCIS (Netherlands)

    Mensink, C.H.J.; Mensink, C.; van Tuijl, Adrianus Johannes Maria; Gierkink, Sander L.J.; Mostert, F.; van der Zee, Ronan A.R.

    2010-01-01

    A 4x45W (EIAJ) monolithic car audio power amplifier is presented that achieves a power dissipation decrease of nearly 2x over standard class AB operation by sharing load currents between loudspeakers. Output signals are conditioned using a common-mode control loop to allow switch placement between

  11. Evaluation of reference current extraction methods for DSP implementation in active power filters

    Energy Technology Data Exchange (ETDEWEB)

    Vardar, K.; Akpinar, E.; Suergevil, T. [Dokuz Eylul University, Department of Electrical and Electronics Engineering, Kaynaklar Kampusu, 35160 Buca, Izmir (Turkey)

    2009-10-15

    Generation of current references constitutes an important part in the control of active power filters (APFs) used in power system, since any inaccuracy in reference currents yields to incorrect compensation. In this paper, harmonic detection methods for generating reference currents have been evaluated on the basis of three-phase balanced and unbalanced load currents processed in the digital signal processor (DSP). The advantages and disadvantages of several methods found in the literature have been discussed on the basis of simulation results. Three of these methods have been programmed in the TMS320F2812 digital signal processor (DSP) unit and their performances are evaluated from the viewpoint of practical considerations. Finally, instantaneous reactive power method to estimate the APF reference currents is implemented and its practical results obtained under balanced and unbalanced loads are given. (author)

  12. A Hierarchical Control Scheme for Reactive Power and Harmonic Current Sharing in Islanded Microgrids

    DEFF Research Database (Denmark)

    Lorzadeh, Iman; Firoozabadi, Mehdi Savaghebi; Askarian Abyaneh, Hossein

    2015-01-01

    of each inverter output current are extracted at primary level and transmitted to the secondary controller. Then, instantaneous circulating currents at different frequencies are calculated and applied by the secondary level to generate proper control signals for accurate reactive power and harmonic......In this paper, a hierarchical control scheme consisting of primary and secondary levels is proposed for achieving accurate reactive power and harmonic currents sharing among interface inverters of distributed generators (DGs) in islanded microgrids. Firstly, fundamental and main harmonic components...... current sharing among the inverters. Consequently, these signals are sent to the primary level and inserted as voltage references after passing the control blocks. In contrast to the conventional virtual impedance schemes, where reactive power and harmonic current sharing are realized at the expense...

  13. Direct Power Control Based Single-Phase AC-DC Converter Controller Design%基于直接功率控制的单相AC-DC变流器控制器设计

    Institute of Scientific and Technical Information of China (English)

    马庆安; 李群湛; 邱大强; 徐英雷; 张丽艳

    2012-01-01

    Single-phase AC-DC full-bridge converter is popular in industry. The aβ-coordinate model was setup for the single-phase system via delaying variables by 90°. Controller was designed based on direct power control. The two-degree-of-freedom PI controller was utilized in this paper to increase the robustness of the system and decrease the overshoot, and sampled voltages were modified to improve the performance. Simulation was conducted based on PSCAD/EMTDC, the results verify the feasibility.%将单相系统延迟90°得到αβ坐标系二相系统,并由此建立了单相变流器的数学模型。基于直接功率控制设计了单相变流器控制系统。提出电压外环使用二自由度PI控制器以提高控制系统的鲁棒性并降低系统启动过程中的超调量,对可能影响系统性能的采样电压进行了修正。最后基于PSCAD/EMTDC的仿真分析验证了方案的可行性。

  14. Implementation of superconducting fault current limiter for flexible operation in the power substation

    Energy Technology Data Exchange (ETDEWEB)

    Song, Chong Suk, E-mail: chong_suk@korea.ac.kr [School of Electrical Engineering, Korea University, Anam dong, Seonbukgu, Seoul 136-713 (Korea, Republic of); Lee, Hansang [School of Railway and Electrical Engineering, Kyungil University, Hayang-eup, Gyeongsan-si, Gyeongsangbuk-do 712-701 (Korea, Republic of); Cho, Yoon-sung [Department of Electric and Energy Engineering, Catholic University of Daegu, Hayang-eup, Gyeongsan-si, Gyeongsangbuk-do 712-702 (Korea, Republic of); Suh, Jaewan [School of Electrical Engineering, Korea University, Anam dong, Seonbukgu, Seoul 136-713 (Korea, Republic of); Jang, Gilsoo, E-mail: gjang@korea.ac.kr [School of Electrical Engineering, Korea University, Anam dong, Seonbukgu, Seoul 136-713 (Korea, Republic of)

    2014-09-15

    Highlights: • The power load concentrated in load centers results in high levels of fault current. • This paper introduces a fault current reduction scheme using SFCLs in substations. • The SFCL is connected in parallel to the bus tie between the two busbars. • The fault current mitigation using SFCLs is verified through PSS/e simulations. - Abstract: The concentration of large-scale power loads located in the metropolitan areas have resulted in high fault current levels during a fault thereby requiring the substation to operate in the double busbar configuration mode. However, the double busbar configuration mode results in deterioration of power system reliability and unbalanced power flow in the adjacent transmission lines which may result in issues such as overloading of lines. This paper proposes the implementation of the superconducting fault current limiter (SFCL) to be installed between the two substation busbars for a more efficient and flexible operation of the substation enabling both single and double busbar configurations depending on the system conditions for guaranteeing power system reliability as well as fault current limitations. Case studies are being performed for the effectiveness of the SFCL installation and results are compared for the cases where the substation is operating in single and double busbar mode and with and without the installation of the SFCL for fault current mitigation.

  15. SoC-Based Dynamic Power Sharing Method with AC-Bus Voltage Restoration for Microgrid Applications

    DEFF Research Database (Denmark)

    Lu, Xiaonan; Sun, Kai; Guerrero, Josep M.

    2012-01-01

    In a microgrid system, distributed energy storage units are commonly employed as the energy buffers. In this paper, a dynamic power sharing method based on the state-of-charge (SoC) of each energy storage unit is proposed. Droop control is employed as the basic control strategy for the distributed...... shared in the energy storage system. The relationship between the droop coefficient and SoC are studied deeply and the small signal model is developed to verify the stability of the control system. It is found that the active power sharing speed becomes faster with higher exponent of SoC. At the same...... energy storage units. By using the proposed method, the coefficients in the conventional droop method are adjusted according to the SoC of each energy storage module. The modules with higher SoC delivers more active power, while those with lower SoC delivers less. Meanwhile, the reactive power is equally...

  16. DC injection into low voltage AC networks

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This report summarises the results of a study investigating the impact of levels of injected DC current injections on a low voltage AC distribution network systems in order to recommend acceptable limits of DC from microgeneration. Relevant literature is reviewed, and the impact of DC levels in distribution transformers, transformer modelling, and instrumental transformers are discussed. The impact of DC in residual current devices (RCD) and in domestic electricity watt hour meters is examined along with DC enhanced corrosion, corrosion failure, and the measurement of DC current injection. Sources of DC injection outlined include DC from computer power supplies, network faults, geomagnetic phenomena, lighting circuits/dimmers, and embedded generators.

  17. Feasibility Implementation of Voltage-Current Waveform Telemetry System in Power Delivery System

    Science.gov (United States)

    Furukawa, Tatsuya; Akagi, Keita; Fukumoto, Hisao; Itoh, Hideaki; Wakuya, Hiroshi; Hirata, Kenji; Ohchi, Masashi

    The electric power is indispensable for modern life. However, there is a problem of harmonic disturbance when the harmonic power runs into electronic devices. To overcome the problem and realize a stable supply of the electric power is an important issue. In this study, we have developed a voltage-current waveform telemetry system for the remote measurement of the harmonics in the power delivery lines. The system consists of sensors, preamplifiers, a single board computer, and power collectors. Improvements are made on all of these components except the sensors. The power collector is a coil that can be placed around the same power line that we measure. We have designed the power collector by a finite element method(FEM) so that it can provide enough electricity for the computer to work properly. Thus, no other power source such as a battery except the secondary rechargeable battery for the recovery is necessary at the measurement place. The preamplifier in the new system is a single-supply differential amplifier circuit, and the single board computer has an inexpensive SH-3 CPU. Through experiments, we have confirmed that the power collector can provide sufficient electricity and that the new system can successfully measure the waveforms and the harmonics in power delivery systems.

  18. 交流电机离散时间电流调节器的设计%Discrete-time Current Regulator Design for AC Machine

    Institute of Scientific and Technical Information of China (English)

    杨立永; 田安民

    2011-01-01

    分析了运行在较高基频与采样频率的比值下异步电机的离散时间电流调节器的特点,该情况普遍应用在高速列车驱动和大型牵引驱动上.若电流调节器的设计不能很好地满足控制系统离散特性,在较高的基频与采样频率比值下,系统会发生严重的振荡或者不稳定响应.通过一个含SVPWM延迟的离散时域交流电机模型,设计离散时域复矢量电流调节器.仿真和实验结果证明该调节器具有非常优越的稳定性和鲁棒性,充分满足了控制系统的离散特性.%The behaviors of discrete-time current regulators for AC machines operating at high ratios of fundamental-tosampling frequencies are analyzed, a situation common for high speed automotive drives and large traction drives. When the current regulator design does not properly incorporate the effects of the discrete nature of the controller, the highly oscillatory,or unstable response can occur,at high ratios of fundamental-to-sampling frequencies. As a part of this investigation,a discrete-time domain AC machine model is developed that includes the delays associated with SVPWM. This model is used to design a discrete-time domain version of the complex vector current regulator that demonstrates improved response compared with the other regulators studied. Simulation and the experimental results prove that the complex vector peoformance indice has very superior stability and robustness, fully meets the discrete control system.

  19. A Novel DBC Layout for Current Imbalance Mitigation in SiC MOSFET Multichip Power Modules

    DEFF Research Database (Denmark)

    Li, Helong; Munk-Nielsen, Stig; Beczkowski, Szymon

    2016-01-01

    This paper proposes a novel Direct Bonded Copper (DBC) layout for mitigating the current imbalance among the paralleled SiC MOSFET dies in multichip power modules. Compared to the traditional layout, the proposed DBC layout significantly reduces the circuit mismatch and current coupling effect......, which consequently improves the current sharing among the paralleled SiC MOSFET dies in power module. Mathematic analysis and circuit model of the DBC layout are presented to elaborate on the superior features of the proposed DBC layout. Simulation and experimental results further verify the theoretical...

  20. A Novel DBC Layout for Current Imbalance Mitigation in SiC MOSFET Multichip Power Modules

    DEFF Research Database (Denmark)

    Li, Helong; Munk-Nielsen, Stig; Beczkowski, Szymon

    2016-01-01

    This letter proposes a novel direct bonded copper (DBC) layout for mitigating the current imbalance among the paralleled SiC MOSFET dies in multichip power modules. Compared to the traditional layout, the proposed DBC layout significantly reduces the circuit mismatch and current coupling effect......, which consequently improves the current sharing among the paralleled SiC MOSFET dies in power module. Mathematic analysis and circuit model of the DBC layout are presented to elaborate the superior features of the proposed DBC layout. Simulation and experimental results further verify the theoretical...

  1. Correlation of Electrical Noise with Non-radiative Current for High Power QWLs

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The characteristics of low-frequency electrical noise, voltage-current (V-I) and electrical derivation for 980nm InGaAsP/InGaAs/GaAs high power double quantum well lasers(DQWLs) are measured under different conditions. The correlation of the low-frequency electrical noise with surface non-radiative current of devices is discussed. The results indicate the low-frequency electrical noise of 980nm DQWLs with high power is mainly 1/f noise and has good relation with the device surface current at low injection.

  2. High critical current of Ti-sheathed MgB{sub 2} wires for AC and weight-critical applications

    Energy Technology Data Exchange (ETDEWEB)

    Alessandrini, M; Fang, H; Hanna, M; Putman, P; Zhou, Y X; Salama, K [Department of Mechanical Engineering and Texas Center for Superconductivity, University of Houston, Houston, TX 77204-4006 (United States)

    2006-01-15

    The peculiar features of magnesium diboride make it suitable for many potential applications. In the last four years of investigation of MgB{sub 2}, the scientific community's research was mainly motivated by features such as low cost, compatibility with straightforward processing methods, relatively high critical temperature, and absence of weak links between grains. Other applications suggest the accentuation of other MgB{sub 2} properties. In particular its very low mass density makes it attractive for space activities, where the cost per kilogram for orbiting is still a huge obstacle, e.g. the cost of transport to low Earth orbit can reach 15 k$ kg{sup -1}. In order to promote the use of this compound for space activities, we tested titanium as a sheath material. Titanium is non-magnetic and its alloys are almost half the weight of steel but with yield stresses up to three times higher. We fabricated Ti-sheathed MgB{sub 2} through the powder-in-tube process. These wires show similar results to those sheathed with Fe. At 4 K the critical current density J{sub c} is well above 7 x 10{sup 5} A cm{sup -2}. The interface between the superconducting intermetallic compound and the lightweight sheath does not show any evidence of reaction and diffusion up to 900 deg. C. An analysis was carried out using x-ray diffraction, scanning electron microscopy with an energy dispersive spectrometer, and electron microprobe analysis.

  3. FPGA-Based Digital Current Switching Power Amplifiers Used in Magnetic Bearing Systems

    Science.gov (United States)

    Wang, Yin; Zhang, Kai; Dong, Jinping

    For a traditional two-level current switching power amplifier (PA) used in a magnetic bearing system, its current ripple is obvious. To increase its current ripple performance, three-level amplifiers are designed and their current control is generally based on analog and logical circuits. So the required hardware is complex and a performance increase from the hardware adjustment is difficult. To solve this problem, a FPGA-based digital current switching power amplifier (DCSPA) was designed. Its current ripple was obviously smaller than a two-level amplifier and its control circuit was much simpler than a tri-level amplifier with an analog control circuit. Because of the field-programmable capability of a FPGA chip used, different control algorithms including complex nonlinear algorithms could be easily implemented in the amplifier and their effects could be compared with the same hardware.

  4. Electric Vehicle to Power Grid Integration Using Three-Phase Three-Level AC/DC Converter and PI-Fuzzy Controller

    Directory of Open Access Journals (Sweden)

    Khairy Sayed

    2016-07-01

    Full Text Available This paper presents the control and simulation of an electric vehicle (EV charging station using a three-level converter on the grid-side as well as on the EV-side. The charging station control schemes with three-level AC/DC power conversion and a bidirectional DC/DC charging regulator are described. The integration of EVs to the power grid provides an improvement of the grid reliability and stability. EVs are considered an asset to the smart grid to optimize effective performance economically and environmentally under various operation conditions, and more significantly to sustain the resiliency of the grid in the case of emergency conditions and disturbance events. The three-level grid side converter (GSC can participate in the reactive power support or grid voltage control at the grid interfacing point or the common coupling point (PCC. A fuzzy logic proportional integral (FL-PI controller is proposed to control the GSC converter. The controllers used are verified and tested by simulation to evaluate their performance using MATLAB/SIMULINK. The comparison of a PI-controller and a PI-Fuzzy controller for the EV charging station shows the effectiveness of the proposed FL-PI controller over conventional PI controller for same circuit operating conditions. A good performance for PI-Fuzzy in terms of settling time and peak overshoot can observed from the simulation results.

  5. Induction cascade with electro-explosive commutation of current for amplification of electric pulse power

    CERN Document Server

    Grabovskij, E V; Kuznetsov, V V; Lototskij, A P; Khaustov, E V; Khalimullin, Y A; Kasyanov, N Y; Kormilitsyn, A I; Filatov, V A; Shkolnikov, E Y

    2002-01-01

    Paper describes a circuit of power amplification induction cascade based on a two-loop solenoid and electrically exploded conductors serving as current breakers. Due to retention of the general magnetic flow current breaking in the first loop of accumulator results in current amplification in the second loop and in accelerated actuation of the second electrically exploded conductor. Current switching to load occurs with 20-fold reduction of charging current front duration and increase of its amplitude. Time to charge coil is selected within 300-350 mu s limits

  6. Improvement of Power Flow Calculation with Optimization Factor Based on Current Injection Method

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2014-01-01

    Full Text Available This paper presents an improvement in power flow calculation based on current injection method by introducing optimization factor. In the method proposed by this paper, the PQ buses are represented by current mismatches while the PV buses are represented by power mismatches. It is different from the representations in conventional current injection power flow equations. By using the combined power and current injection mismatches method, the number of the equations required can be decreased to only one for each PV bus. The optimization factor is used to improve the iteration process and to ensure the effectiveness of the improved method proposed when the system is ill-conditioned. To verify the effectiveness of the method, the IEEE test systems are tested by conventional current injection method and the improved method proposed separately. Then the results are compared. The comparisons show that the optimization factor improves the convergence character effectively, especially that when the system is at high loading level and R/X ratio, the iteration number is one or two times less than the conventional current injection method. When the overloading condition of the system is serious, the iteration number in this paper appears 4 times less than the conventional current injection method.

  7. Analysis and implementation of power managment and control strategy for six-phase multilevel ac drive system in fault condition

    DEFF Research Database (Denmark)

    Sanjeevikumar, P.; Grandi, Gabriele; Blaabjerg, Frede

    2016-01-01

    This research article exploits the power management algorithm in post-fault conditions for a six-phase (quad) multilevel inverter. The drive circuit consists of four 2-level, three-phase voltage source inverter (VSI) supplying a six-phase open-end windings motor or/impedance load, with circumstan......This research article exploits the power management algorithm in post-fault conditions for a six-phase (quad) multilevel inverter. The drive circuit consists of four 2-level, three-phase voltage source inverter (VSI) supplying a six-phase open-end windings motor or/impedance load...... sources. The developed post-fault algorithm is applied when there is a fault by one VSI and the load is fed from the remaining three healthy VSIs. In faulty conditions the multilevel outputs are reduced from 3-level to 2-level, but still the system propagates with degraded power. Numerical simulation...

  8. A RESEARCH TO HIGH-PERFORMANCE MULTI-LEVEL SINGLEPHASE AC/DC POWER FACTOR CORRECT SWITCHING CONVERTER

    Institute of Scientific and Technical Information of China (English)

    Gao Chao

    2008-01-01

    This letter studies and analyzes the working features of main circuit of tri-level boost Power Factor Correct (PFC) converter and the advantages of tri-level switch converter in aspects of bearing high-voltage of power components,overall system loss and magnetic component selection based upon the single-level boost PFC switch converter. Besides,relying on the application of mi-croprocessor in power converter technology and DSP (Digital Signal Processing) chip's strong cal-culating capacity,the letter presents the adoption of modified scheme of tri-level boost PFC converter under the control of predictive control algorithm. Moreover,the operating principle and control method are specified,the results of circuit test and analysis are provided and the advantages of pre-dictive control technology-based multi-level boost PFC converter is verified.

  9. Modeling and Compensation Design for a Power Hardware-in-the-Loop Simulation of an AC Distribution System

    Energy Technology Data Exchange (ETDEWEB)

    Ainsworth, Nathan; Hariri, Ali; Prabakar, Kumaraguru; Pratt, Annabelle; Baggu, Murali

    2016-11-21

    Power hardware-in-the-loop (PHIL) simulation, where actual hardware under text is coupled with a real-time digital model in closed loop, is a powerful tool for analyzing new methods of control for emerging distributed power systems. However, without careful design and compensation of the interface between the simulated and actual systems, PHIL simulations may exhibit instability and modeling inaccuracies. This paper addresses issues that arise in the PHIL simulation of a hardware battery inverter interfaced with a simulated distribution feeder. Both the stability and accuracy issues are modeled and characterized, and a methodology for design of PHIL interface compensation to ensure stability and accuracy is presented. The stability and accuracy of the resulting compensated PHIL simulation is then shown by experiment.

  10. Effect of Tower Shadow and Wind Shear in a Wind Farm on AC Tie-Line Power Oscillations of Interconnected Power Systems

    DEFF Research Database (Denmark)

    Tan, Jin; Hu, Weihao; Wang, Xiaoru

    2013-01-01

    This paper describes a frequency domain approach for evaluating the impact of tower shadow and wind shear effects (TSWS) on tie-line power oscillations. A simplified frequency domain model of an interconnected power system with a wind farm is developed. The transfer function, which relates the ti...

  11. Stray current induced corrosion in lightning rod cables of 525 kV power lines towers: a case study

    Directory of Open Access Journals (Sweden)

    Wojcicki, F. R.

    2003-12-01

    Full Text Available With the growth of several areas in modem society, the necessity to generate and carry electrical energy to big cities has greatly increased. Cables supported by power towers with galvanized steel foundation usually carry energy. As the foundations are underground they may cause high rates of corrosion. These are usually detected by a conventional potential measurement using a Cu/CuSO4 reference electrode. It is believed that corrosion results from stray currents that flow through the ground to close the loop between neighboring towers. Stray currents originate in the lightning rod cables of the power line towers, induced by the strong electromagnetic and electric fields of the energized power lines. The intensity and direction of those currents were measured, indicating substantial values of both their AC and DC components. The potential of the tower ground system, measured in the perpendicular direction of the main axis of the power line, was plotted as a function of the distance to the tower base. The results clearly indicated the tendency to corrosive attack in the anodic towers as reflected by the slope of the plot, whereas no signs of corrosion could be found in the reverse slope, confirming the visual inspection of the foundation. The profile of the potential plots could be changed providing the electric insulation of the lightning rod cable.

    Con el crecimiento de varias áreas en la sociedad moderna, la necesidad de generar y conducir la energía eléctrica a las grandes ciudades ha aumentado enormemente. La energía, normalmente, se transporta por cables sostenidos por torres de energía con base de acero galvanizado. Cuando las bases son subterráneas, pueden ocasionar altas tasas de corrosión. Estas, normalmente, se detectan por la medida convencional del potencial empleando un electrodo de referencia de Cu/CuSO4. Se cree que la corrosión es el resultado de corrientes perdidas que fluyen a través de la

  12. Surface magnetic properties of Co{sub 69}Fe{sub 4}Si{sub 15}B{sub 12} when DC and AC currents flow through the ribbon

    Energy Technology Data Exchange (ETDEWEB)

    Fal-Miyar, Vanessa [Departamento de Fisica. Universidad de Oviedo, c/ Calvo Sotelo s.n., 33007, Oviedo (Spain); Kurlyandskaya, Galina V. [Universidad del Pais Vasco UPV-EHU, Dpto. Electricidad y Electronica, Apdo. 644, 48080, Bilbao (Spain); Garcia, Jose A. [Departamento de Fisica. Universidad de Oviedo, c/ Calvo Sotelo s.n., 33007, Oviedo (Spain); Elbaile, Laura [Departamento de Fisica. Universidad de Oviedo, c/ Calvo Sotelo s.n., 33007, Oviedo (Spain)]. E-mail: elbaile@uniovi.es; Crespo, Rosario D. [Departamento de Fisica. Universidad de Oviedo, c/ Calvo Sotelo s.n., 33007, Oviedo (Spain); Tejedor, Marcos [Departamento de Fisica. Universidad de Oviedo, c/ Calvo Sotelo s.n., 33007, Oviedo (Spain)

    2006-09-15

    Surface magnetic properties of Co{sub 69}Fe{sub 4}Si{sub 15}B{sub 12} amorphous ribbons with longitudinal and transverse anisotropies when an electrical current flows through the ribbons has been studied. Observations were performed by the transverse magnetooptical Kerr effect. A DC electrical current caused a shift of the transverse hysteresis loop and AC current produced an increase of the coercive field.

  13. Electrical Structure of Future Off-shore Wind Power Plant with a High Voltage Direct Current Power Transmission

    DEFF Research Database (Denmark)

    Sharma, Ranjan

    to control and as such a high current capacity of the WPP side VSC might be required. Detailed simulation results are included in the report. The other option is to use a DC chopper, the results of which are also presented in detail in the report. It is observed that a DC chopper can provide a simple...... are related to surplus reactive power and added losses. On the other hand, HVDC transmission system can be arbitrarily long and for long distance power transmission requirement it provides much better efficiency compared to a corresponding HVAC system. HVDC may provide a viable solution for high power...... to trip off during temporary grid side faults, commonly described as low voltage fault-ride-through requirement. There are four different fault-ride-through options discussed in the report. The first option includes controlling of collector network frequency. This provides a very good opportunity to use...

  14. Enhancing the Frequency Adaptability of Periodic Current Controllers for Grid-Connected Power Converters

    DEFF Research Database (Denmark)

    Yang, Yongheng; Zhou, Keliang; Blaabjerg, Frede

    2015-01-01

    (PR) and Repetitive Controllers (RC). The synchronization is actually to detect the instantaneous grid information (e.g., frequency and phase of the grid voltage) for the current control, which is commonly performed by a Phase-Locked-Loop (PLL) system. As a consequence, harmonics and deviations......It is mandatory for grid-connected power converters to synchronize the feed-in currents with the grid. Moreover, the power converters should produce feed-in currents with low total harmonic distortions according to the demands, by employing advanced current controllers, e.g., Proportional Resonant...... deviations. Experiments on a single-phase grid-connected inverter system are presented, which have verified the proposals and also the effectiveness of the frequency adaptive current controllers....

  15. Assessment of Inrush Current for Power Transformers by Three-Dimensional Representation

    Directory of Open Access Journals (Sweden)

    Mohammad Yazdani-Asrami

    2012-03-01

    Full Text Available For power transformers, the magnitude of the first peak of inrush current is ten times more than the rated load current. The main feature of this current is its high amplitude and second harmonic content. An uncontrolled inrush current may lead to the inadvertent operation of the circuit over-current protection systems. Furthermore, the magnetic stress produced by the inrush current may destroy mechanical structure and windings of transformers. In addition, this current has undesirable effects on electricity quality, extra loss, and reduction of useful life of transformer. In this paper, the peak value of inrush current in three-phase power transformer with Y-Y connection has been calculated and shown with a three-dimensional representation and its harmonic spectrum has been evaluated. It should be mentioned that, this phenomenon occurs because in four-wire Y-Y connection three-phase power transformers, the probability of saturation in phases is lower in contrast with other possible connection of three-phase transformers.

  16. A study on the interference effects for tidal current power rotors

    Institute of Scientific and Technical Information of China (English)

    Chul-Hee; JO; Kang-Hee; LEE; Jin-Young; YIM

    2010-01-01

    Due to global warming, the need to secure an alternative resource has become more important nationally. With the high tidal range of up to 9.7 m on the west coast of Korea, numerous tidal current projects are being planned and constructed. To extract a significant quantity of power, a tidal current farm with a multi-arrangement is necessary in the ocean. The rotor, which initially converts the energy, is a very important component because it affects the efficiency of the entire system, and its performance is determined by various design variables. The power generation is strongly dependent on the size of the rotor and the incoming flow velocity. However, the interactions between devices also contribute significantly to the total power capacity. Therefore, rotor performance considering the interaction problems needs to be investigated for generating maximum power in a specific field. This paper documents a performance study of devices considering the interference between rotating rotors with axial, transverse and diagonal arrangements.

  17. Optical properties of the atmospheric pressure helium plasma jet generated by alternative current (a.c.) power supply

    Science.gov (United States)

    Ilik, Erkan; Akan, Tamer

    2016-05-01

    In this work, an atmospheric pressure plasma jet (APPJ) was produced to generate cold flowing post-discharge plasma of pure helium gas. The main aim of this study was to generate cold flowing APPJ of pure helium gas and to determine how their optical emission spectrum change influences varying different flow rates. Lengths of early, middle, and late post-discharge plasma (jet) regions and their fluctuations were determined, respectively. Then, ignition condition dependence of the post-discharge plasma for flow rate was specified at a constant voltage. Spectroscopic studies of an atmospheric pressure plasma jet of helium were presented via analyzing OH, N2, N2+, oxygen, and helium intensities for various flow rates.

  18. Control of current inverters in decentral power systems as active filters; Regelung von Netzstromrichtern in dezentralen Energiesystemen als aktive Filter

    Energy Technology Data Exchange (ETDEWEB)

    Merfert, Igor; Lindemann, Andreas [Magdeburg Univ. (Germany). Lehrstuhl fuer Leistungselektronik

    2007-07-01

    Besides their main task, decentralized power generators can combine electric power generation with system services if the inverter has current capability to spare. This paper deals with the system services, power quality improvement and a reactive power compensation, in a fuel cell based decentralized electrical power generator. A control strategy and a practical realization are introduced. (orig.)

  19. Enhancement of the power supply systems in RFX-mod towards 2 MA plasma current

    Energy Technology Data Exchange (ETDEWEB)

    Novello, Luca, E-mail: luca.novello@igi.cnr.it [Consorzio RFX, Euratom-ENEA Association, Padova (Italy); Zamengo, Andrea; Ferro, Alberto; Zanotto, Loris; Barp, Marco; Cavazzana, Roberto; Finotti, Claudio; Recchia, Mauro; Gaio, Elena [Consorzio RFX, Euratom-ENEA Association, Padova (Italy)

    2011-10-15

    The recent start-up improvements brought to RFX-mod have allowed increasing the plasma current in the range 1.7-1.9 MA, but still they proved to be not sufficient to routinely and reliably reach higher values of plasma current that would be very useful for the present studies on enhanced confinement. The need for higher poloidal flux variation together with the overabundant available toroidal flux has led to the study of a rearrangement of the power supply system with the aim of increasing the first at the expenses of the latter. Thanks to the flexibility of the power supply system, composed of modular thyristor converters, the rearrangement has been easily obtained and the resulting enhanced poloidal flux capability scenario described in the paper allows a two step plasma current ramp-up. In order to increase as much as possible the plasma current up to the nominal value of 2 MA it is necessary to fully exploit the thyristor converter power capability, in particular in the first ramp-up phase. In the paper a detailed verification of their maximum performance is presented. The first results obtained after power supply reconfiguration are very good, with plasma current kept constant at about 2 MA for 100 ms. The enabled operation at very high plasma current requires also an optimization of the magneto hydro dynamics (MHD) mode coil power supplies that are required to provide higher current values. Therefore a dedicated study of their control system has been worked out, which allowed understanding how to increase as much as possible the output current without losing the dynamic performance, so keeping the efficiency in the control of dominant and secondary modes, which is essential to obtain good and reproducible discharges.

  20. Fabrication of alumina films with laminated structures by ac anodization

    Directory of Open Access Journals (Sweden)

    Hiroyo Segawa

    2014-01-01

    Full Text Available Anodization techniques by alternating current (ac are introduced in this review. By using ac anodization, laminated alumina films are fabricated. Different types of alumina films consisting of 50–200 nm layers were obtained by varying both the ac power supply and the electrolyte. The total film thickness increased with an increase in the total charge transferred. The thickness of the individual layers increased with the ac voltage; however, the anodization time had little effect on the film thickness. The laminated alumina films resembled the nacre structure of shells, and the different morphologies exhibited by bivalves and spiral shells could be replicated by controlling the rate of increase of the applied potentials.

  1. Control of grid interactive AC microgrids

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Guerrero, Josep M.; Chen, Zhe

    2010-01-01

    and reliability, becomes an attractive candidate for the configuration of future electrical power system. This paper gives a brief review of grid interactive ac microgrid configurations. Control methods for power electronics interfaced DER units in grid interactive ac microgrids are discussed. In addition......, microgrid controls and power management strategies are presented. Future trends of microgrid are discussed pointing out how this concept can be a key to achieve a more intelligent and flexible AC grid....

  2. The Current-voltage Characteristics Simulation of the Betavoltaic Power Supply

    Directory of Open Access Journals (Sweden)

    S.U. Urchuk

    2015-12-01

    Full Text Available In order to optimize betavoltaic power supply it was calculated the current-voltage characteristics when changing the depth of the upper p-layer and at changing doping levels structure areas. It is shown that an increase in the depth reduces the short-circuit current and thus reduces the open circuit voltage. It has been observed that the concentration of the lightly doped region more significantly influence on the current-voltage characteristics than the depth of the p-n-junction. The concentration of the n-region, equal to 1014 cm – 3, can be considered as during betavoltaic power supply design. It is shown that, by increasing the power supply activity the conversion efficiency of the structure increases, too.

  3. A micro-power LDO with piecewise voltage foldback current limit protection

    Institute of Scientific and Technical Information of China (English)

    Wei Hailong; Liu Youbao; Guo Zhongjie; Liao Xue

    2012-01-01

    To achieve a constant current limit,low power consumption and high driving capability,a micro-power LDO with a piecewise voltage-foldback current-limit circuit is presented.The current-limit threshold is dynamically adjusted to achieve a maximum driving capability and lower quiescent current of only 300 nA.To increase the loop stability of the proposed LDO,a high impedance transconductance buffer under a micro quiescent current is designed for splitting the pole that exists at the gate of the pass transistor to the dominant pole,and a zero is designed for the purpose of the second pole phase compensation.The proposed LDO is fabricated in a BiCMOS process.The measurement results show that the short-circuit current of the LDO is 190 mA,the constant limit current under a high drop-out voltage is 440 mA,and the maximum load current under a low drop-out voltage is up to 800 mA.In addition,the quiescent current of the LDO is only 7 μA,the load regulation is about 0.56% on full scale,the line regulation is about 0.012%/V,the PSRR at 120 Hz is 58 dB and the drop-out voltage is only 70 mV when the load current is 250 mA.

  4. Single-Phase Direct AC-AC Boost Converter

    Directory of Open Access Journals (Sweden)

    LUCANU, M.

    2014-08-01

    Full Text Available The paper presents a single-phase direct AC-AC boost converter. The circuit of the converter is simple and it has good performances, irrespective of the load nature. The adequate functioning and high performance of the circuit (the efficiency and waveform of the absorbed input current were tested both by simulation and experimentally.

  5. Comparison of mechanical drive concepts for high power ac-traction locomotives; Vergleich mechanischer Antriebskonzepte fuer Drehstrom-Hochleistungslokomotiven

    Energy Technology Data Exchange (ETDEWEB)

    Koerner, O. [Siemens AG, Nuernberg (Germany). A und D LD T D2

    2004-11-01

    Due to the recent progress with rare earth magnets, a direct drive based on a permanent magnetic synchronous machine could be employed in high power locomotives. An unsprung and a partially suspended direct drive are compared by the criteria of complexity, costs, vertical wheel-rail forces and dynamic loads on the drive with a conventional cardan hollow shaft drive and a nose suspended drive. (orig.)

  6. In situ measurements of wind and current speed and relationship between output power and turbulence

    Science.gov (United States)

    Duran Medina, Olmo; Schmitt, François G.; Sentchev, Alexei; Calif, Rudy

    2015-04-01

    In a context of energy transition, wind and tidal energy are sources of clean energy with the potential of partially satisfying the growing demand. The main problem of this type of energy, and other types of renewable energy remains the discontinuity of the electric power produced in different scales, inducing large fluctuations also called intermittency. This intermittency of wind and tidal energy is inherent to the turbulent nature of wind and marine currents. We consider this intermittent power production in strong relation with the turbulent intermittency of the resource. The turbulence theory is multifractal energy cascades models, a classic in physics of turbulence. From earlier studies in atmospheric sciences, we learn that wind speed and the aggregate power output are intermittent and multifractal over a wide range of scales [Calif and Schmitt 2014]. We want to extend this study to a marine current turbine and compare the scaling properties for those renewable energy sources. We consider here coupling between simultaneous velocity time series and output power from a wind turbine and a marine current turbine. Wind turbine data were obtained from Denmark and marine current data from Western Scheldt, Belgium where a prototype of a vertical and horizontal marine current turbines are tested. After an estimation of their Fourier density power spectra, we study their scaling properties in Kolmogorov's theory and the framework of fully developed turbulence. Hence, we employ a Hilbert-based methodology, namely arbitrary-order Hilbert spectral analysis [Calif et al. 2013a, 2013b] to characterize the intermittent property of the wind and marine current velocity in order to characterize the intermittent nature of the fluid. This method is used in order to obtain the spectrum and the corresponding power law for non-linear and non-stationary time series. The goal is to study the non-linear transfer characteristics in a multi-scale and multi-intensity framework.

  7. AC Short-Circuit Current Calculation Scheme Based on Parameter Optimization%基于参数优化的交流系统短路电流计算方案

    Institute of Scientific and Technical Information of China (English)

    张帆; 赵勇; 苏寅生; 李智欢; 杨银国

    2015-01-01

    In view of unreasonable and even often optimistic assessment of power system short-circuit current, based on analysis of basic principles of AC short-circuit current calculation, from the perspective of result modification, a set of short-circuit current calcu-lation scheme is provided. Firstly, a linear modification formula to calculate the short-circuit current, including the coefficient of cur-rent correction K and the deviation of current ΔI is given;and then the optimization principles and the objective function for determi-ning the above two parameters based on actual short-circuit faults are proposed, which can promise the calculating results with high precision under the premise of not lower than measured values. Application of this scheme to actual short-circuit current evaluation of CSG reveals that, compared with existing schemes, the proposed scheme promises the results with conservation and precision, and can be regarded as an effective supplement for short-circuit current calculating tools.%针对目前电力系统短路电流水平评估不合理甚至经常偏乐观的情况, 基于对交流系统短路电流计算基本原理的分析, 从计算结果修正的角度提出了一套短路电流计算方案. 首先提出了包含电流修正系数K和电流偏差修正量ΔI的短路电流线性修正公式; 然后给出了基于电网实际故障确定这两个参数的寻优原则和目标函数, 保证短路电流计算值在不低于实测值的前提下仍具有较高的精度. 针对南方电网实际短路故障的应用结果表明, 相比于已有的短路电流计算方案, 所提出的计算方案合理有效, 在评估系统短路电流水平时能兼具保守性和准确性, 是对现有短路电流计算工具的有效补充.

  8. Adaptation to high current using low external resistances eliminates power overshoot in microbial fuel cells

    KAUST Repository

    Hong, Yiying

    2011-10-01

    One form of power overshoot commonly observed with mixed culture microbial fuel cells (MFCs) is doubling back of the power density curve at higher current densities, but the reasons for this type of overshoot have not been well explored. To investigate this, MFCs were acclimated to different external resistances, producing a range of anode potentials and current densities. Power overshoot was observed for reactors acclimated to higher (500 and 5000. Ω) but not lower (5 and 50. Ω) resistances. Acclimation of the high external resistance reactors for a few cycles to low external resistance (5. Ω), and therefore higher current densities, eliminated power overshoot. MFCs initially acclimated to low external resistances exhibited both higher current in cyclic voltammograms (CVs) and higher levels of redox activity over a broader range of anode potentials (-0.4 to 0. V; vs. a Ag/AgCl electrode) based on first derivative cyclic voltammetry (DCV) plots. Reactors acclimated to higher external resistances produced lower current in CVs, exhibited lower redox activity over a narrower anode potential range (-0.4 to -0.2. V vs. Ag/AgCl), and failed to produce higher currents above ∼-0.3. V (vs. Ag/AgCl). After the higher resistance reactors were acclimated to the lowest resistance they also exhibited similar CV and DCV profiles. Our findings show that to avoid overshoot, prior to the polarization and power density tests the anode biofilm must adapt to low external resistances to be capable of higher currents. © 2011 Elsevier B.V.

  9. AC losses in circular arrangements of parallel superconducting tapes

    DEFF Research Database (Denmark)

    Kühle (fratrådt), Anders Van Der Aa; Træholt, Chresten; Däumling, Manfred

    1998-01-01

    The DC and AC properties of superconducting tapes connected in parellel and arranged in a single closed layer on two tubes (correspondig to power cable models with infinite pitch) with different diameters are compared. We find that the DC properties, i.e. the critical currents of the two arrangem......The DC and AC properties of superconducting tapes connected in parellel and arranged in a single closed layer on two tubes (correspondig to power cable models with infinite pitch) with different diameters are compared. We find that the DC properties, i.e. the critical currents of the two...... arrangements, scale with the number of tapes and hence appear to be independent of the diameter.However, the AC loss per tape (for a given current per tape) appears to decrease with increasing diameter of the circular arrangement. Compared to a model for the AC loss in a continuous superconducting layer...... (Monoblock model) the measured values are about half an order of magnitude higher than expected for the small diameter arrangement. When compared to the AC loss calculated for N individual superconducting tapes using a well known model ( Norris elliptical) the difference is slightly smaller....

  10. Study of eddy current power loss from outer-winding coils of a magnetic position sensor

    CERN Document Server

    Liu, C P; Chang, Y H; Yu, C S; Wu, K T; Wang, S J; Ying, T F; Huang, D R

    2000-01-01

    The present analysis is concerned with eddy current power loss of a magnetic position sensor, which arises from a non-uniform flux linkage distribution between magnetic material and position sensor. In the paper, a magnetic position sensor system is simplified to be an outer-winding coil along the axial direction of a low carbon steel bar, and developed a numerical model to compute the electrical characteristics by an excited current source. According to the simulated and measured data in this proposed model from 2.52 to 11.37 Oes, eddy current power losses of conducting material have a variation of 6.1% and 9.77%, respectively. Finally, the phases of waveform of the induced output voltage will also be obtained in the conducting material, and have a variation of 3.68% obtained by using the current source in the proposed model.

  11. Current Harmonics Compensation in Microgrids Exploiting the Power Electronics Interfaces of Renewable Energy Sources

    Directory of Open Access Journals (Sweden)

    Ioannis Bouloumpasis

    2015-03-01

    Full Text Available This work presents a method of current harmonic reduction in a distorted distribution system. In order to evaluate the proposed method a grid with high-order current harmonics is assumed. The reduction of current distortion is feasible due to the pulse modulation of an active filter, which consists of a buck-boost converter connected back-to-back to a polarity swapping inverter. For a practical application, this system would be the power electronic interface of a Renewable Energy Source (RES and therefore it changes a source of harmonics to a damping harmonics system. Using the proposed method, the current Total Harmonic Distortion (THD of the grid is reduced below the acceptable limits and thus the general power quality of the system is improved. Simulations in the MATLAB/SIMULINK platform and experiments have been performed in order to verify the effectiveness of the proposed method.

  12. Current Control Method for Distributed Generation Power Generation Plants under Grid Fault Conditions

    DEFF Research Database (Denmark)

    Rodriguez, Pedro; Luna, Alvaro; Hermoso, Juan Ramon

    2011-01-01

    The operation of distributed power generation systems under grid fault conditions is a key issue for the massive integration of renewable energy systems. Several studies have been conducted to improve the response of such distributed generation systems under voltage dips. In spite of being less s...... the current ratings of the converter is introduced. Moreover, a novel flexible algorithm has been proposed in order to regulate easily the injection of positive and negative currents for general purpose applications....

  13. Carrier phase shifted SPWM based on current sourced multi-modular converter for active power filter

    Institute of Scientific and Technical Information of China (English)

    王立乔; 李建林; 张仲超

    2004-01-01

    A novel current-source active power filter(APF)based on multi-modular converter with carrier phase-shifted SPWM(CPS-SPWM)technique is proposed.With this technique,the effect of equivalent high switching frequency converter is obtained with low switching frequency converter.It is very promising in current-source APF that adopt superconducting magnetic energy storage component.

  14. A mechanical connector design for high-current, high-coulomb pulsed power systems

    Energy Technology Data Exchange (ETDEWEB)

    Susoeff, A.R.; Hawke, R.S.; Leighton, K.S.

    1992-02-25

    A technique to make reliable high-current, high-coulomb electrical contact was developed for transmitting power into railguns. The method uses spring loaded removable connectors that are installed independently from the launcher. The simple rod-type design and absence of fastener holes allow maximum utilization of material mechanical properties. Repeated experiments with 9.5-mm diameter connectors demonstrated reliable pulsed charge transfer of 200 coulombs at currents of over 400kA. 20 refs.

  15. Assessment of Power Potential of Tidal Currents and Impacts of Power Extraction on Flow Conditions in Indonesia

    Science.gov (United States)

    Orhan, Kadir; Mayerle, Roberto

    2017-04-01

    kinetic energy dissipation. Preliminary results show the effectiveness of the method to capture the effects of power extraction, and wake characteristics and recovery reasonably well with low computational cost. It was found that although there is no significant change regarding water levels, an impact has been observed on current velocities as a result of velocity profile adjusting to the increased momentum transfer. It was also seen that, depending on the level of energy dissipation, currently recommended tidal farm configurations can be conservative regarding the spacing of the tidal turbines.

  16. High-Bandwidth, High-Efficiency Envelope Tracking Power Supply for 40W RF Power Amplifier Using Paralleled Bandpass Current Sources

    DEFF Research Database (Denmark)

    Høyerby, Mikkel Christian Wendelboe; Andersen, Michael Andreas E.

    2005-01-01

    This paper presents a high-performance power conversion scheme for power supply applications that require very high output voltage slew rates (dV/dt). The concept is to parallel 2 switching bandpass current sources, each optimized for its passband frequency space and the expected load current....... The principle is demonstrated with a power supply, designed for supplying a 40 W linear RF power amplifier for efficient amplification of a 16-QAM modulated data stream...

  17. 基于 DSP 的逆变交流电阻焊电源控制%Control of Power Source for AC Inverter Resistance Welding on the Basis of DSP

    Institute of Scientific and Technical Information of China (English)

    曹彪; 李海波; 庞少辉

    2015-01-01

    常用的工频电阻焊机输出不连续的类正弦交流波形,由于电流过零时间长,同等功率下电流峰值过大,造成焊接时工件加热不连续,易产生飞溅,针对上述问题,设计了一种基于数字信号处理器(DSP)的逆变交流控制系统。该系统以 DSP 为控制核心,包括信息检测、脉宽调制(PWM)输出控制、人机交互、输入输出(I /O)接口、故障检测等电路和相应的控制软件。系统采用 PWM控制方式调节焊接变压器的初级电压,实现了大范围电流调节条件下较为连续的输出;具有电流、电压、功率3种反馈控制模式和多种频率选择,在每半个周期内实现快速反馈调节,提高了控制精度,改善了交流电阻焊机的工艺适应性。%Single-phase AC resistance welder provides alternating current similar to sine-wave.Due to the long zero-crossing time and high peak current,welding heating becomes discontinuous and splash occurs easily.In order to solve these problems,a control system for AC resistance welding,which takes DSP(Digital Signal Processor)as the controlling core and is composed of information detection,PWM (Pulse Width Modulation)output control,human-computer interaction,I /O (Input/Output)interface and fault detection circuits,is developed,and the correspond-ing software is also designed to assure system function.By employing PWMcontrol to adjust the primary voltage of welding transformer,a relative continuous output in wide current range is ensured.The control system possesses three feedback control modes respectively in terms of current,voltage and power,provides several output frequen-cies,and implements quick and stable output control in half a period.Thus,both high control precision and adaptive welding process can be achieved.

  18. Influence of AC line faults on HVDC commutation failure transient characteristics in DC/AC interconnected power grid%直流馈入后交流线路故障对换相失败瞬态特征的影响

    Institute of Scientific and Technical Information of China (English)

    张汝莲; 赵成勇; 卫鹏杰

    2011-01-01

    高压直流(HVDC)输电系统故障会使交流系统电气故障特性复杂化.在PSCAD/EMTDC环境下,基于含宁东--山东直流输电系统的山东电网的电磁暂态模型,研究当青岛换流站附近交流线路不同位置发生不同故障时,直流系统换相失败对交流系统电气瞬态特征的影响.直流系统换相失败对故障线路的平行线路影响最为严重,重点研究交流线路不同故障引一起直流换相失败对平行线路电气特性的影响.仿真分析结果表明,平行线路的故障相电流畸变程度随着故障位置和故障类型的不同而不同,在线路中间发生故障比线路两端故障时畸变严重,发生单相接地短路故障比三相接地短路故障时崎变严重,故在线路中间发生单相接地短路故障时畸变最严重.%The faults of HVDC power transmission system make the electrical characteristics of AC system more complex. In PSCAD/EMTDC environment,based on the electromagnetic transient model of Shandong grid containing Ningdong-Shandong DC transmission system,the influence of HVDC commutation failure on the electrical transient characteristics of AC system is studied for different faults occurring at different positions of AC line near Qingdao substation. During the period of commutation failure,the parallel line of the faulty line is most affected. The influence of commutation failure,caused by different faults of AC line,on the electrical transient characteristics of parallel line is detailed. According to the comparative analysis of simulative results ,the current distortion of the faulty phase of parallel line varies with the fault positions and fault types. It is more serious when the fault occurs in the middle of the line than that when the fault occurs at terminals;it is more serious during single-phase grounding fault than that during three-phase grounding fault. When single-phase grounding fault occurs in the middle of the line ,the current distortion of the

  19. Fatigue Life Prediction of Mooring Chains for a Floating Tidal Current Power Station

    Institute of Scientific and Technical Information of China (English)

    Fengmei Jing; Liang Zhang; Zhong Yang

    2012-01-01

    As a kind of clean and renewable energy,tidal current energy is becoming increasingly popular all over the world with the shortage of energy and environmental problems becoming more and more severe.A floating tidal current power station is a typical type of tidal current power transformers which can sustain the loads of wind,waves,and current,and even the extreme situation of a typhoon.Therefore,the mooring system must be reliable enough to keep the station operating normally and to survive in extreme situations.The power station examined in this paper was installed at a depth of 40 m.A 44 mm-diameter R4-RQ4 chain was chosen,with a 2 147 kN minimum break strength and 50 kN pretension.Common studless link chain was used in this paper.Based on the Miner fatigue cumulative damage rule,S-N curves of chains,and MOSES software,a highly reliable mooring system was designed and analyzed.The calculation results show that the mooring system designed is reliable throughout a 10-year period.It can completely meet the design requirements of American Petroleum institution (API).Therefore,the presented research is significant for advancing the design of this kind of power station.

  20. High Power Laser Science and Engineering Design and current progress of the Apollon 10 PW project

    OpenAIRE

    ZOU, J-P; Le Blanc, C; Dimitrios PAPADOPOULOS; Chériaux, G; Georges, Patrick; Mennerat, G.; Druon, Frédéric; Lecherbourg, L.; Pellegrina, A; Ramirez, Philippe; Giambruno, F; Fréneaux, A; Leconte, F; Badarau, D; Boudenne, J. M

    2015-01-01

    International audience; The objective of the Apollon project is the generation of 10 PW peak power pulses of 15 fs at 1 shot/minute. In this paper the Apollon facility design, the technological challenges and the current progress of the project will be presented.