WorldWideScience

Sample records for medium voltage level

  1. Control and Testing of a Dynamic Voltage Restorer (DVR) at Medium Voltage Level

    DEFF Research Database (Denmark)

    Nielsen, John Godsk; Newman, Michael; Nielsen, Hans Ove

    2004-01-01

    power sensitive loads from voltage sags. This paper reports practical test results obtained on a medium voltage (10 kV) level using a DVR at a Distribution test facility in Kyndby, Denmark. The DVR was designed to protect a 400-kVA load from a 0.5-p.u. maximum voltage sag. The reported DVR verifies......The dynamic voltage restorer (DVR) has become popular as a cost effective solution for the protection of sensitive loads from voltage sags. Implementations of the DVR have been proposed at both a low voltage (LV) level, as well as a medium voltage (MV) level; and give an opportunity to protect high...

  2. Control and Testing of a Dynamic Voltage Restorer (DVR) at Medium Voltage Level

    DEFF Research Database (Denmark)

    Nielsen, John Godsk; Newman, Michael; Nielsen, Hans Ove

    2004-01-01

    The dynamic voltage restorer (DVR) has become popular as a cost effective solution for the protection of sensitive loads from voltage sags. Implementations of the DVR have been proposed at both a low voltage (LV) level, as well as a medium voltage (MV) level; and give an opportunity to protect high...... power sensitive loads from voltage sags. This paper reports practical test results obtained on a medium voltage (10 kV) level using a DVR at a Distribution test facility in Kyndby, Denmark. The DVR was designed to protect a 400-kVA load from a 0.5-p.u. maximum voltage sag. The reported DVR verifies...... duration voltage sags were created using a controllable LV breaker fed by a 630 kVA Distribution transformer placed upstream of the sensitive load. The fault currents in excess of 12 kA were designed and created to obtain the required voltage sags. It is concluded the DVR works well in all operating...

  3. A dynamic voltage restorer (DVR) with selective harmonic compensation at medium voltage level

    DEFF Research Database (Denmark)

    Newman, M.J.; Holmes, D.G.; Nielsen, J.G.

    2005-01-01

    Dynamic voltage restorers (DVRs) are now becoming more established in industry to reduce the impact of voltage sags to sensitive loads. However, DVRs spend most of their time in standby mode, since voltage sags occur very infrequently, and hence their utilization is low. In principle, it would...... voltage harmonic compensation capabilities with minimal effect on the sag compensation performance of the basic DVR. The proposed controller has been experimentally verified on a medium-voltage (10 kV) three-phase DVR prototype under a range of conditions, including distorted supply voltages, nonlinear...... loads, and operation during distorted voltage sags....

  4. A dynamic voltage restorer (DVR) with selective harmonic compensation at medium voltage level

    DEFF Research Database (Denmark)

    Newman, M.J.; Holmes, D.G.; Nielsen, J.G.

    2005-01-01

    be advantageous if the series-connected inverter of a DVR could also be used to compensate for any steady-state load voltage harmonics, since this would increase the power quality "value-added" benefits to the grid system. However, before this can be done, consideration must be given to the control of steady......-state power through the DVR, the increased losses, and the low modulation depths at which the scheme must operate to achieve acceptable harmonic compensation performance. This paper presents a selective harmonic feedback control strategy that can be easily added to medium-voltage DVR systems to provide...

  5. A Robust Control Scheme for Medium-Voltage-Level DVR Implementation

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Loh, Poh Chiang; Li, Yun Wei

    2007-01-01

    of Hinfin controller weighting function selection, inner current loop tuning, and system disturbance rejection capability is presented. Finally, the designed control scheme is extensively tested on a laboratory 10-kV MV-level DVR system with varying voltage sag (balanced and unbalanced) and loading (linear......In this paper, a robust control scheme with an outer Hinfin voltage control loop and an inner current control loop is designed and implemented on a medium-voltage (MV)-level dynamic voltage restorer (DVR) system. Through a simple selection of weighting functions, the synthesized Hinfin controller....../nonlinear load and induction motor load) conditions. It is shown that the proposed control scheme is effective in both balanced and unbalanced sag compensation and load disturbance rejection, as its robustness is explicitly specified....

  6. Five-Level Active-Neutral-Point-Clamped DC/DC Converter for Medium-Voltage DC Grids

    DEFF Research Database (Denmark)

    Liu, Dong; Deng, Fujin; Chen, Zhe

    2017-01-01

    /dt, reduce voltage stress on the transformer, and thus reduce the electromagnetic interference (EMI) and increase reliability. An elimination method for the dead time effect is also proposed along with the proposed modulation strategy by employing a switch in series with the flying capacitor, which can......This paper proposes a five-level active-neutralpoint- clamped (5L-ANPC) dc/dc converter for applications in medium voltage dc (MVDC) grids. A modulation strategy is proposed for the 5L-ANPC dc/dc converter to generate multilevel voltage waveforms, which can effectively reduce voltage change rate dv...

  7. Medium voltage three-level converters for the grid connection of a multi-MW wind turbine

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Helle, Lars; Munk-Nielsen, Stig

    2009-01-01

    Three-level (3L) neutral point clamped (NPC), flying capacitor (FC), and H-bridge (HB) voltage source converters (VSCs) as a grid-side full-scale medium voltage (MV) converter are modeled, controlled, and simulated for the grid connection of a hypothetical 6MW wind turbine. Via the converter...... topological features and the simulation results demonstrating the converter performance, these three 3L-VSCs are discussed and compared in terms of power density and reliability, which can be considered as two of the most important criteria for the converters placed in wind turbine nacelles. Given the grid...

  8. Investigation and Improvement of Transient Response of DVR at Medium Voltage Level

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Wei Li, Yun; Chaing Loh, Poh

    2007-01-01

    An area of interest for dynamic voltage restorer (DVR) research is the damping of transient oscillations initiated at the start and at the recovery instant from a voltage sag. Nonlinear loads, with harmonic currents close to the DVR filter resonance frequency, can also excite the resonance...

  9. Medium Voltage Three-level Converters for the Grid Connection of aMulti-MW Wind Turbine

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Helle, Lars; Munk-Nielsen, Stig

    2009-01-01

    Three-level (3L) neutral point clamped (NPC), flying capacitor (FC), and H-bridge (HB) voltage source converters (VSCs) as a grid-side full-scale medium voltage (MV) converter are modeled, controlled, and simulated for the grid connection of a hypothetical 6MW wind turbine. Via the converter...... topological features and the simulation results demonstrating the converter performance, these three 3L-VSCs are discussed and compared in terms of power density and reliability, which can be considered as two of the most important criteria for the converters placed in wind turbine nacelles. Given the grid...... connection circuit (without capacitive switching ripple filters), the 3L-HB-VSC is expected to be superior with respect to power density and reliability over the 3L-NPC- and -FC-VSCs....

  10. Medium voltage three-level converters for the grid connection of a multi-MW wind turbine

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Helle, Lars; Munk-Nielsen, Stig

    2009-01-01

    Three-level (3L) neutral point clamped (NPC), flying capacitor (FC), and H-bridge (HB) voltage source converters (VSCs) as a grid-side full-scale medium voltage (MV) converter are modeled, controlled, and simulated for the grid connection of a hypothetical 6MW wind turbine. Via the converter...... topological features and the simulation results demonstrating the converter performance, these three 3L-VSCs are discussed and compared in terms of power density and reliability, which can be considered as two of the most important criteria for the converters placed in wind turbine nacelles. Given the grid...... connection circuit (without capacitive switching ripple filters), the 3L-HB-VSC is expected to be superior with respect to power density and reliability over the 3L-NPC- and -FC-VSCs....

  11. A dulal-functional medium voltage level DVR to limit downstream fault currents

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Li, Yun Wei; Vilathgamuwa, D. Mahinda

    2007-01-01

    , the DVR will therefore be tasked to mitigate even more faults involving downstream loads. Large fault currents would flow through the DVR during a downstream fault before the opening of a circuit breaker. This will cause the voltage at point of common coupling (PCC) to drop, which would affect the loads...... on the other parallel feeders connected to PCC. Furthermore, if not controlled properly, the DVR might also contribute to this PCC voltage sag in the process of compensating the missing voltage, thus further worsening the fault situation. To limit the flow of large line currents, and therefore restore the PCC...

  12. A dulal-functional medium voltage level DVR to limit downstream fault currents

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Li, Yun Wei; Vilathgamuwa, D. Mahinda

    2007-01-01

    , the DVR will therefore be tasked to mitigate even more faults involving downstream loads. Large fault currents would flow through the DVR during a downstream fault before the opening of a circuit breaker. This will cause the voltage at point of common coupling (PCC) to drop, which would affect the loads...... on the other parallel feeders connected to PCC. Furthermore, if not controlled properly, the DVR might also contribute to this PCC voltage sag in the process of compensating the missing voltage, thus further worsening the fault situation. To limit the flow of large line currents, and therefore restore the PCC...... voltage as well as protect the DVR system components, a downstream fault limiting function is proposed and integrated in the DVR operation. A flux-charge-model feedback algorithm is implemented so that the DVR would act as a large virtual inductance in series with the distribution feeder in fault...

  13. Power converters for medium voltage networks

    CERN Document Server

    Islam, Md Rabiul; Zhu, Jianguo

    2014-01-01

    This book examines a number of topics, mainly in connection with advances in semiconductor devices and magnetic materials and developments in medium and large-scale renewable power plant technologies, grid integration techniques and new converter topologies, including advanced digital control systems for medium-voltage networks. The book's individual chapters provide an extensive compilation of fundamental theories and in-depth information on current research and development trends, while also exploring new approaches to overcoming some critical limitations of conventional grid integration te

  14. Gas insulated switchgear and switches for application at medium voltages

    Energy Technology Data Exchange (ETDEWEB)

    Bapat, A.

    1995-12-31

    The application of gas insulated, metal enclosed and metalclad switchgear at medium voltage levels were discussed. Advantages of SF{sub 6} gas insulated switchgear (GIS) were explained, including reduced maintenance, negligible fire risk, capability of large numbers of operations under load and fault condition, compactness, safety and reliability. Several types of metal enclosed switchgear were described and illustrated. The SF{sub 6} load break switch and the breaking principle were described. Beneficial aspects of GIS for medium voltage (MV) applications and the world-wide scope of its usage was demonstrated. Results of a comparison of metal enclosed air insulated and gas insulated switchgear were discussed. Criteria considered in the comparison were security, protection from environmental influences, maintenance, compartmentation, size, visible break, integrated protection metering and monitoring relays, and voltage sensors. These results proved that GIS MS switchgear offers a reliable, safe, compact and maintenance free equipment alternative to traditional metalclad switchgear. 3 refs., 3 tabs., 4 figs.

  15. Prosedur Strategis Untuk Mengurangi Level Bahaya Arc-Flash Pada Medium Voltage Dengan Metode Koordinasi Proteksi Di PT Ipmomi Paiton

    Directory of Open Access Journals (Sweden)

    inas ratnaning zafirah

    2017-01-01

    Full Text Available Di area sistem kelistrikan, operasi, dan maintenance, perhatian terbesar adalah keselamatan dan keamanan pekerja yang mengoperasikan dan menjaga sistem. Sistem kelistrikan didisain tidak hanya untuk tindakan pencegahan yang diperlukan pada sistem proteksi dan peralatan, tetapi juga harus memperhatikan keselamatan personal untuk tingkat tertentu dari arc-flash atau busur api karena arcing fault. Pada tugas akhir ini, bahaya busur api akan dianalisis dan diperhitungkan. Hasilnya akan diketahui level energi arc-flash atau busur api yang mungkin terjadi sesuai standar NFPA 70E-2004. Data yang nanti digunakan diambil dari plant yang telah ditentukan sebelumnya yaitu PT IPMOMI. Dari data tersebut, parameter – parameter yang diperlukan akan dihitung dan diketahui level busur api. Bila diperlukan, maka juga akan dilakukan resetting atau penambahan rele over current.

  16. A Transformerless Medium Voltage Multiphase Motor Drive System

    Directory of Open Access Journals (Sweden)

    Dan Wang

    2016-04-01

    Full Text Available A multiphase motor has several major advantages, such as high reliability, fault tolerance, and high power density. It is a critical issue to develop a reliable and efficient multiphase motor drive system. In this paper, a transformerless voltage source converter-based drive system for a medium-voltage (MV multiphase motor is proposed. This drive converter employs cascaded H-bridge rectifiers loaded by H-bridge inverters as the interface between the grid and multiphase motor. The cascaded H-bridge rectifier technique makes the drive system able to be directly connected to the MV grid without the phase-shifting transformer because it can offset the voltage level gap between the MV grid and the semiconductor devices, provide near-sinusoidal AC terminal voltages without filters, and draw sinusoidal line current from the grid. Based on a digital signal processor (DSP, a complete improved Phase Disposition Pulse Width Modulation (PD-PWM method is developed to ensure the individual DC-link capacitor voltage balancing for enhancing the controllability and limiting the voltage and power stress on the H-bridge cells. A downscaled prototype is designed and developed based on a nine-phase motor. The experimental results verify the excellent performances of the proposed drive system and control strategy in steady-state and variant-frequency startup operations.

  17. DC Voltage Balance Control Strategy for Medium Voltage Cascaded STATCOM Based on Distributed Control

    OpenAIRE

    Xuehua Zhao; Liping Shi

    2014-01-01

    DC bus capacitors of Medium Voltage Cascaded STATCOM are independent. DC side voltage balance control method is the key influencing factor of current control. The imbalance of DC bus voltage increases harmonic current and affects the safety of device. In this paper, the unbalance mechanism of DC side capacitor voltage is analyzed. Based on the unipolar dual frequency and carrier phase-shifted SPWM (CPS-SPWM) modulation algorithms, the distributed control algorithms, which need multi- FPGA str...

  18. Medium and high voltage power cables market in Europe

    International Nuclear Information System (INIS)

    Kupiec, M.

    1992-06-01

    This note gives an overview of the European market for medium and high voltage power cables. In this text, emphasis is placed on suppliers and important European clients; there is also a brief review of the different techniques for cable laying and utilization in Europe. This not has mainly been drafted from informations supplied by EUROPACABLE

  19. Stator insulation systems for medium voltage PWM drives fed motors

    International Nuclear Information System (INIS)

    Gao, G.; Chen, W.

    2005-01-01

    This paper presents the partial results of a research project that studied the impact of medium voltage PWM ASD (adjustable speed drives) on motor stator insulation system. The findings from this study/ investigation have aided designers to improve the robustness of the insulation system used for ASD-fed motors, based on accelerated laboratory tests. (author)

  20. Power Restoration in Medium Voltage Network Using Multiagent System

    Directory of Open Access Journals (Sweden)

    Miroslav Kovac

    2013-01-01

    Full Text Available The article describes a novel approach to a power restoration in medium voltage power distribution network. It focuses primary at searching of a new network configuration enabling to minimalize the size of faulted area and to restore the power for the highest possible number of loads. It describes characteristic features of medium voltage power distribution network and discusses the implementation of the presented approach in existing networks. A software tool, developed by the authors, including physical simulation of model network and its autonomous control system is described. An example of fault situation in a virtual distribution network is presented. Afterwards, the solution of restoration problem by proposed multiagent system is simulated using the software tool described in the paper.

  1. Ultrasonic nondestructive testing of medium-voltage cables

    International Nuclear Information System (INIS)

    Le Baut, P.Y.

    1976-01-01

    Ultrasonic non destructive testing of medium-voltage cables for Thomson-Brandt consists of: a thickness control of the three layers surrounding the metallic core and a quality control of dielectric, which must be free of voids and impurities. At first time, the feasibility of these different controls has been studied in laboratory. A reflection technique by immersion in water at 20 deg C has been used [fr

  2. Grid Filter Design for a Multi-Megawatt Medium-Voltage Voltage Source Inverter

    DEFF Research Database (Denmark)

    Rockhill, A.A.; Liserre, Marco; Teodorescu, Remus

    2011-01-01

    constraints. To achieve this goal, new concepts such as virtual harmonic content and virtual filter losses are introduced. Moreover, a new passive damping technique that provides the necessary damping with low losses and very little degradation of the high-frequency attenuation is proposed.......This paper describes the design procedure and performance of an LCL grid filter for a medium-voltage neutral point clamped (NPC) converter to be adopted for a multimegawatt wind turbine. The unique filter design challenges in this application are driven by a combination of the medium voltage...... converter, a limited allowable switching frequency, component physical size and weight concerns, and the stringent limits for allowable injected current harmonics. Traditional design procedures of grid filters for lower power and higher switching frequency converters are not valid for a multi...

  3. Lightning-induced overvoltages in medium voltage distribution systems and customer experienced voltage spikes

    Energy Technology Data Exchange (ETDEWEB)

    Sabiha, N. A.

    2010-07-01

    In Finland, distribution transformers are frequently subjected to lightning strokes for which they are continuously protected by spark-gaps. So, the breakdown probability of medium voltage (MV) spark-gaps is modeled using the Gaussian distribution function under an impulse voltage test in accordance with the IEC 60060-1 standard. The model is presented in the form of the well-known Gaussian tail probability. Accordingly, a modified probabilistic model is proposed to study the effect of impulse voltage superimposed on the ac voltage on the breakdown probability of MV spark-gaps. The modified model is verified using experimental data, where the experimental setup is arranged to generate a range of impulse voltages superimposed on the ac voltages. The experimental verification shows evidence of the efficacy of the proposed probabilistic model. Furthermore, the proposed model is used to evaluate single-phase, two-phase and three-phase spark-gap breakdown probabilities in the case of lightning induced overvoltages. These breakdown probabilities are used along with the simplified Rusck expression to evaluate the performance of MV overhead lines above a perfectly conducting ground under lightning-induced overvoltages using a statistical approach. In order to study the overvoltages propagating through the transformer to its low voltage side, the high frequency model of the transformer is investigated. First, the investigation is carried out using model introduced by Piantini at no-load condition. This model is modified to take more than one resonance frequency into consideration. Therefore, the frequency response of the simulated transient voltage is improved. A verification of the modified model is carried out through the comparison between the experimental and simulation results, in which the time domain simulation is carried out using ATP/EMTP while MATLAB is used to identify the model parameters. As this model is found suitable only for unloaded transformer, an

  4. Ozone Sensor for Application in Medium Voltage Switchboard

    Directory of Open Access Journals (Sweden)

    Letizia De Maria

    2009-01-01

    Full Text Available The application of a new spectroscopic type fiber sensor for ozone detection in electrical components of Medium Voltage (MV network is evaluated. The sensor layout is based on the use of an optical retroreflector, to improve the detection sensitivity, and it was especially designed for detecting in situ rapid changes of ozone concentration. Preliminary tests were performed in a typical MV switchboard. Artificial defects simulated predischarge phenomena arising during real operating conditions. Results are discussed by a comparison with data simultaneously acquired with a standard partial discharge system.

  5. The frequency characteristics of medium voltage distribution system impedances

    Directory of Open Access Journals (Sweden)

    Liviu Emil Petrean

    2009-10-01

    Full Text Available In this paper we present the frequency characteristics of impedances involved in the electrical equivalent circuit of a large medium voltage distribution system. These impedances influence harmonics distortions propagation occurring due to the nonsinusoidal loads. We analyse the case of a 10 kV large urban distribution system which supplies industrial, commercial and residential customers. The influence of various parameters of the distribution network on the frequency characteristics are presented, in order to assess the interaction of harmonic distortion and distribution system network.

  6. Decentralized Adaptive Overcurrent Protection for Medium Voltage Maritime Power Systems

    DEFF Research Database (Denmark)

    Ciontea, Catalin-Iosif; Bak, Claus Leth; Blaabjerg, Frede

    2016-01-01

    control unit. The new adaptive protection method is based on communication between the overcurrent relays and the equipment that could affect the protection system, such as circuit breakers and generators. Using PSCAD, the proposed method is implemented in a test medium voltage maritime power system......More and more maritime applications as marine vessels and offshore platforms need an adaptive protection power system. However, the adaptive protection is yet to be implemented in the maritime sector. Usually, the adaptive protection implies the existence of a central control unit that monitors...... the entire electrical network and changes the relay settings accordingly, but this approach is not adequate for the maritime power systems. This paper propose a decentralized adaptive protection method, where each protection relay is able to identify by itself the network status without the need of a central...

  7. Active power filter for medium voltage networks with predictive current control

    Energy Technology Data Exchange (ETDEWEB)

    Verne, Santiago A.; Valla, Maria I. [Laboratorio de Electronica Industrial, Control e Instrumentacion (LEICI), Facultad de Ingenieria, Universidad Nacional de La Plata and CONICET, La Plata (Argentina)

    2010-12-15

    A transformer less Shunt Active Power Filter (SAPF) for medium voltage distribution networks based on Multilevel Diode Clamped Inverter is presented in this paper. Converter current control is based on a Model Predictive strategy, which gives very fast current response. Also, the algorithm includes voltage balancing capability which is essential for proper converter operation. The presented current control algorithm is naturally applicable to converters with an arbitrary number of levels with reduced computational effort by virtue of the incorporation of switching restrictions which are necessary for reliable converter operation. The performance of the proposed algorithm is evaluated by means of computer simulations. (author)

  8. Thermal Stress Analysis of Medium-Voltage Converters for Smart Transformers

    DEFF Research Database (Denmark)

    Andresen, Markus; Ma, Ke; De Carne, Giovanni

    2017-01-01

    A smart transformer (ST) can take over an important managing role in the future electrical distribution grid system and can provide many advanced grid services compared to the traditional transformer. However, the risk is that the advanced functionality is balanced out by a lower reliability....... To address this concern, this work conducts thermal stress analysis for a modular multilevel converter (MMC), which is a promising solution for the medium voltage stage of the ST. The focus is put on the mission profiles of the transformer and the impact on the thermal stress of power semiconductor devices....... Normal operation at different power levels and medium voltage grid faults in a feeder fed by a traditional transformer are considered as well as the electrical and the thermal stress of the disconnection and the reconnection procedures. For the validation, the thermal stress of one MMC cell is reproduced...

  9. Energy Storage Characteristic Analysis of Voltage Sags Compensation for UPQC Based on MMC for Medium Voltage Distribution System

    Directory of Open Access Journals (Sweden)

    Yongchun Yang

    2018-04-01

    Full Text Available The modular multilevel converter (MMC, as a new type of voltage source converter, is increasingly used because it is a distributed storage system. There are many advantages of using the topological structure of the MMC on a unified power quality controller (UPQC, and voltage sag mitigation is an important use of the MMC energy storage system for the power quality compensation process. In this paper, based on the analysis of the topology of the MMC, the essence of energy conversion in a UPQC of voltage sag compensation is analyzed; then, the energy storage characteristics are calculated and analyzed to determine the performance index of voltage sag compensation; in addition, the simulation method is used to verify the voltage sag compensation characteristics of the UPQC; finally, an industrial prototype of the UPQC based on an MMC for 10 kV of medium voltage distribution network has been developed, and the basic functions of UPQC have been tested.

  10. On the Distribution of Lightning Current among Interconnected Grounding Systems in Medium Voltage Grids

    Directory of Open Access Journals (Sweden)

    Guido Ala

    2018-03-01

    Full Text Available This paper presents the results of a first investigation on the effects of lightning stroke on medium voltage installations’ grounding systems, interconnected with the metal shields of the Medium Voltage (MV distribution grid cables or with bare buried copper ropes. The study enables us to evaluate the distribution of the lightning current among interconnected ground electrodes in order to estimate if the interconnection, usually created to reduce ground potential rise during a single-line-to-ground fault, can give place to dangerous situations far from the installation hit by the lightning stroke. Four different case studies of direct lightning stroke are presented and discussed: (1 two secondary substations interconnected by the cables’ shields; (2 two secondary substations interconnected by a bare buried conductor; (3 a high voltage/medium voltage station connected with a secondary substation by the medium voltage cables’ shields; (4 a high voltage/medium voltage station connected with a secondary substation by a bare buried conductor. The results of the simulations show that a higher peak-lowering action on the lighting-stroke current occurs due to the use of bare conductors as interconnection elements in comparison to the cables’ shields.

  11. Frequency pulling in a low-voltage medium-power gyrotron

    Science.gov (United States)

    Luo, Li; Du, Chao-Hai; Huang, Ming-Guang; Liu, Pu-Kun

    2018-04-01

    Many recent biomedical applications use medium-power frequency-tunable terahertz (THz) sources, such as sensitivity-enhanced nuclear magnetic resonance, THz imaging, and biomedical treatment. As a promising candidate, a low-voltage gyrotron can generate watt-level, continuous THz-wave radiation. In particular, the frequency-pulling effect in a gyrotron, namely, the effect of the electron beam parameters on the oscillation frequency, can be used to tune the operating frequency. Most previous investigations used complicated and time-consuming gyrotron nonlinear theory to study the influence of many beam parameters on the interaction performance. While gyrotron linear theory investigation demonstrates the advantages of rapidly and clearly revealing the physical influence of individual key beam parameters on the overall system performance, this paper demonstrates systematically the use of gyrotron linear theory to study the frequency-pulling effect in a low-voltage gyrotron with either a Gaussian or a sinusoidal axial-field profile. Furthermore, simulations of a gyrotron operating in the first axial mode are carried out in the framework of nonlinear theory as a contrast. Close agreement is achieved between the two theories. Besides, some interesting results are obtained. In a low-current sinusoidal-profile cavity, the ranges of frequency variation for different axial modes are isolated from each other, and the frequency tuning bandwidth for each axial mode increases by increasing either the beam voltage or pitch factor. Lowering the voltage, the total tuning ranges are squeezed and become concentrated. However, the isolated frequency regions of each axial mode cannot be linked up unless the beam current is increased, meaning that higher current operation is the key to achieving a wider and continuous tuning frequency range. The results presented in this paper can provide a reference for designing a broadband low-voltage gyrotron.

  12. A High-Voltage Level Tolerant Transistor Circuit

    NARCIS (Netherlands)

    Annema, Anne J.; Geelen, Godefridus Johannes Gertrudis Maria

    2001-01-01

    A high-voltage level tolerant transistor circuit, comprising a plurality of cascoded transistors, including a first transistor (T1) operatively connected to a high-voltage level node (3) and a second transistor (T2) operatively connected to a low-voltage level node (2). The first transistor (T1)

  13. Current Decoupling Control Strategy of Medium Voltage Cascaded Multilevel STATCOM

    Directory of Open Access Journals (Sweden)

    Zhao Xuehua

    2014-10-01

    Full Text Available As one of effective regulation methods, static synchronous compensator (STATCOM has been widespread used to regulate dynamic reactive power and solve dynamic voltage stability problems into power-grid. Through the analysis of mathematical model, cascaded STATCOM, which is constructed by several cascaded H-bridges, is a nonlinear, multivariable, strongly coupled system. It will make difficulties in the design and practical application of controller. In this paper, mathematical models of cascaded STATCOM in a -b- c and d-q coordinates are deduced. Based on the theory of internal model control and PI control strategy, the internal decoupling control algorithm is introduced to realize independent control of active current and reactive current. At the same time, decoupling control algorithms are designed and decoupling control models are given and simulated. From the combined circuit topology and control with multi-FPGA, the simulation and experimental platform of cascaded SVG, which use the control algorithms of double-loop control with the current inner loop and capacitor voltage outer loop. Both in a-b-c coordinates and d-q-0 coordinates, experiment and simulation results show that three-phase current of STATCOM has good tracking performance and control precision, which show the regulator design method and parameters setting are feasible and effective.

  14. Triple Line-Voltage Cascaded VIENNA Converter Applied as the Medium-Voltage AC Drive

    Directory of Open Access Journals (Sweden)

    Jia Zou

    2018-04-01

    Full Text Available A novel rectifier based on a triple line-voltage cascaded VIENNA converter (LVC-VC was proposed. Compared to the conventional cascaded H-bridge converters, the switch voltage stress is lower, and the numbers of switches and dc capacitors are fewer under similar operating conditions in the proposed new multilevel converter. The modeling and control for the LVC-VC ware presented. Based on the analysis of the operation principle of the new converter, the power factor correction of the proposed converter was realized by employing a traditional one-cycle control strategy. The minimum average value and maximum harmonic components of the dc-link voltages of the three VIENNA rectifier modules ware calculated. Three VIENNA dc-link voltages were unbalanced under the unbalanced load conditions, so the zero sequence current was injected to the three inner currents for balancing three VIENNA dc-link voltages. Simulation and the results of the experiment verified the availability of the new proposed multilevel converter and the effectiveness of the corresponding control strategy applied.

  15. An ANN Based Capicitor Voltage Balancing Method For Neutral Point Clamped Multi-Level Inverter

    OpenAIRE

    P.J.S. Praveen,; Narendra Bavisetti

    2015-01-01

    Multi-level inverters are became popular for usage in medium voltage, low voltage power applications due to flexibility in control and better performance characteristics in terms of harmonic regulation. Neutral point clamped are popular as they require less number of sources as their input when compared with their counter parts i.e. cascaded multi-level inverters and found to be reliable when compared with flying capacitor based multi-level inverters. But when neutral clamped tech...

  16. RF Channel Characteristics of the Medium-voltage Power Line for PLC

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S.H. [Keochang Polytechnic College, Keochang (Korea); Kim, K.H. [Korea Electrotechnology Research Institute, Changwon (Korea); Rhee, Y.C. [Kyungnam University, Masan (Korea); Shin, C.C. [Ajou University, Suwon (Korea)

    2002-07-01

    In this paper, the channel characteristics of the medium voltage(22.9kV) power line to analysis the broadband power line communication in the frequency range up to 30MHz was measured. With the wideband electrical coupler in the operating frequency range from DC to 30MHz, we measured characteristic impedance, noise and attenuation of the medium voltage power line, and then characteristic impedance was measured at the state of unloaded medium voltage power line by Scattering parameter method of Vector Network Analyzer. As a measurement result, Channel impedance shows 100{approx}380{omega} at the less than 15MHz and 70{approx}230{omega} at the more than 15 MHz. Noise characteristics of power line shows -75dBm at 20MHz and Narrowband interference noise was from 3 MHz to 7 MHz. (author). 8 refs., 8 figs., 1 tab.

  17. Simulation of the temperature field distribution in medium-voltage vacuum interrupter and experimental verification

    Science.gov (United States)

    Sun, W.; Liu, H. L.; Cai, Y. G.; Li, Y. L.; Zhou, H. Y.; Zhou, Y.

    2018-01-01

    The temperature field distribution in the medium-voltage vacuum interrupter decides the thermal stability of it. In this paper, the simulation model of a kind of 12kV/3150A/40kA medium-voltage vacuum interrupter is constructed, and conductive bridge model is used. This paper simulates current contraction and Joule heating between contacts, and solves relevant problems using the function of the thermal-electrical coupling in the finite element software ANSYS. Steady-state temperature rise of vacuum interrupter at rated current and transient temperature rise of vacuum interrupter at short-time withstand current are calculated. Influence of the contact situation on vacuum interrupter temperature rise is analyzed. Steady-state temperature rise experiments for the interrupter are carried out, and experiment results verify the accuracy of simulation results. The results are useful in the designing and optimizing of medium-voltage vacuum interrupter.

  18. NEMO medium voltage converter factory acceptance, operational and final integration tests

    Energy Technology Data Exchange (ETDEWEB)

    Cocimano, Rosanna, E-mail: cocimano@lns.infn.i [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy)

    2011-01-21

    The NEMO Collaboration, as part of the KM3NeT EU-funded consortium, is developing technical solutions for the construction of a cubic-kilometer scale neutrino telescope in the Mediterranean sea several kilometers below the sea level and far from the shore. In this framework, after years of design, development, assembly and testing the Alcatel deep sea medium voltage power converter (MVC) is ready for deployment at 100 km from the Capo Passero shore station. The MVC converts the 10 kV to an instrument-friendly 375 V for a 10 kW power. The MVC will be presented with focus on the factory acceptance, operational and final integration tests that recently have been carried out.

  19. Verification of a Novel Method of Detecting Faults in Medium-Voltage Systems with Covered Conductors

    Directory of Open Access Journals (Sweden)

    Mišák Stanislav

    2017-06-01

    Full Text Available This paper describes the use of new methods of detecting faults in medium-voltage overhead lines built of covered conductors. The methods mainly address such faults as falling of a conductor, contacting a conductor with a tree branch, or falling a tree branch across three phases of a medium-voltage conductor. These faults cannot be detected by current digital relay protection systems. Therefore, a new system that can detect the above mentioned faults was developed. After having tested its operation, the system has already been implemented to protect mediumvoltage overhead lines built of covered conductors.

  20. Guest Editorial: Flexible Operation and Control for Medium Voltage Direct-Current (MVDC) Grid

    DEFF Research Database (Denmark)

    Li, Yong; Guerrero, Josep M.; Siano, Pierluigi

    2017-01-01

    We appreciate very much the support from the IET Power Electronics editorial board for this Special Issue on ‘Flexible Operation and Control for Medium Voltage Direct-Current (MVDC) Grid’. In this final version for publication, 15 papers have been selected for this Special Issue. Three papers...... relate to the topology of MVDC converter, four papers relate to the control of MVDC converter, four papers relate to the introduction of application fields of MVDC grid, and four papers relate to the semiconductor power device and drives towards the application in the medium- and high-voltage DC grid....

  1. Impact and Cost Evaluation of Electric Vehicle Integration on Medium Voltage Distribution Networks

    DEFF Research Database (Denmark)

    Wu, Qiuwei; Cheng, Lin; Pineau, Ulysse

    2013-01-01

    This paper presents the analysis of the impact of electric vehicle (EV) integration on medium voltage (MV) distribution networks and the cost evaluation of replacing the overloaded grid components. A number of EV charging scenarios have been studied. A 10 kV grid from the Bornholm Island in the c...

  2. Calculations of lightning-induced voltages in medium voltage distribution lines

    Energy Technology Data Exchange (ETDEWEB)

    Munhoz Rojas, Patricio E. [Instituto de Tecnologia para o Desenvolvimento (LACTEC/UFPR), Curitiba, PR (Brazil)], E-mail: patricio@lactec.org.br; Pinto, Cleverson Luiz da Silva [Companhia Paranaense de Energia (COPEL), Curitiba, PR (Brazil)], E-mail: cleverson@copel.com

    2007-07-01

    The objective of this paper is to show the results of a new computer program, written in Mat Lab environment, that is intended to calculate the lightning induced voltages in multi-conductor non-homogeneous lines, in order to be able to evaluate the impact of the usual protective measures implemented against lightning-induced disturbances. The main new features of this program are: a coupling model in terms of the scalar potentials referred to a remote ground was adopted; the coupling to the vertical conductors was considered in a manner similar to rest of the line; the describing equations were converted into a system of coupled ordinary differential equations, by a discretization only in space, which was subsequently solved using the powerful ODE solvers existing in Mat Lab. The validation of the new program has been performed by comparing its predicted results with other theoretical and computational results available in the literature and also with other experimental results published in the literature. It is shown that the agreement with other well established theoretical results is very good and, also, that the agreement between the newly calculated results and some published experimental results is better than previously obtained results. (author)

  3. A Medium-Voltage Motor Drive with a Modular Multilevel PWM Inverter Part I. Experimental Verification by a 400-V, 15-kW Downscaled Model

    Science.gov (United States)

    Hagiwara, Makoto; Nishimura, Kazutoshi; Akagi, Hirofumi

    This paper presents a medium-voltage motor drive with a three-phase modular multilevel PWM inverter and focuses on its control method and operating performance. This motor drive is particularly suitable for fans, blowers, pumps, and compressors, in which the load torque is proportional to the square of the rotating speed. Particular attention is paid to the dc-capacitor voltage fluctuation of each chopper-cell because it may affect the voltage rating of the power switching devices used. This paper describes the theoretical equations related to the amount of the voltage fluctuation. A downscaled model rated at 400V and 15kW is designed and built to confirm the validity and effectiveness of the nine-level (17-level in line-to-line) PWM inverter that is intended for use in medium-voltage motor drives to achieve energy savings.

  4. Synchronised Voltage Space Vector Modulation for Three-level Inverters with Common-mode Voltage Elimination

    DEFF Research Database (Denmark)

    Oleschuk, Valentin; Blaabjerg, Frede

    2002-01-01

    A novel method of direct synchronous pulse-width modulation (PWM) is disseminated to three-level voltage source inverters with control algorithms with elimination of the common-mode voltages in three-phase drive systems with PWM. It provides smooth pulses-ratio changing and a quarter-wave symmetry...

  5. Optimized Control Strategy for a Medium-Voltage DVR-Theoretical Investigations and Experimental Results

    DEFF Research Database (Denmark)

    Meyer, Christoph; De Doncker, Rik W.; Li, Yun Wei

    2008-01-01

    the needed voltage amplitude. To avoid this drawback, an optimized control strategy is presented in this paper, which is able to reduce the needed injection voltage of the DVR and concurrently to mitigate the transient distortions at the load side. In the following paper, a brief introduction of the basic...... a small fraction of the energy stored in the DC-link capacitor is used, which makes it impractical for DVRs to compensate relatively long voltage sags. Present control strategies are only able to minimize the distortions at the load or to allow a better utilization of the storage system by minimizing...... DVR principle will be given. Next, three standard control strategies will be compared and an optimized control strategy is developed in this paper. Finally, experimental results using a medium-voltage 10-kV DVR setup will be shown to verify and prove the functionality of the presented control strategy...

  6. Impact of DC Voltage Enhancement on Partial Discharges in Medium Voltage Cables : An Empirical Study with Defects at Semicon-Dielectric Interface

    NARCIS (Netherlands)

    Shekhar, A.; Feng, Xianyong; Gattozzi, Angelo; Hebner, Robert E.; Wardell, Douglas; Strank, Shannon; Rodrigo Mor, A. R.; Ramirez Elizondo, L.M.; Bauer, P.

    2017-01-01

    A scientific consensus is emerging on the benefits of direct current (DC) distribution in medium voltage (MV) power systems of ships and cities. At least 50% space savings and increased power transfer capacity are estimated with enhanced voltage DC operation of electric cables. The goal of this

  7. Geometrical effects in JTE rings termination for 4H-SiC medium-voltage devices

    Science.gov (United States)

    Yuan, Lei; Song, Qingwen; Tang, Xiaoyan; Zhang, Yimeng; Guo, Lixin; Zhang, Yimen; Zhang, Yuming

    2017-12-01

    Compared with a conventional junction termination extension (JTE) structure, JTE rings termination used in power devices could achieve a higher blocking performance without any extra processing. In this paper, the geometrical effects in JTE rings are analyzed and demonstrated for medium voltage applications of 4H-SiC power devices. According to the simulation results, it is found that the first space (D 1) of JTE rings has a strong effect on both the maximum breakdown voltage and the optimal implantation dose window. To achieve excellent blocking characteristics, D 1 should kept at around 2 μm which could be implemented conveniently by contact lithography. Furthermore, the optimized design of JTE rings is verified by experimental results of 4H-SiC bipolar junction transistors (BJTs) with drifting layer of 20 μm-thickness and doping concentration of 3 × 1015 cm‑3. The measured breakdown voltages are consistent with the observations from simulation results.

  8. Void formation in NiTi shape memory alloys by medium-voltage electron irradiation

    International Nuclear Information System (INIS)

    Schlossmacher, P.; Stober, T.

    1995-01-01

    In-situ electron irradiation experiments of NiTi shape memory alloys, using high-voltage transmission electron microscopes, result in amorphization of the intermetallic compound. In all of these experiments high-voltages more than 1.0 MeV had to be applied in order to induce the crystalline-to-amorphous transformation. To their knowledge no irradiation effects of medium-voltage electrons of e.g. 0.5 MeV have been reported in the literature. In this contribution, the authors describe void formation in two different NiTi shape memory alloys, resulting from in-situ electron irradiation, using a 300 kV electron beam in a transmission electron microscope. First evidence is presented that void formation is correlated with the total oxygen content of the alloys

  9. Voltage Balancing Method on Expert System for 51-Level MMC in High Voltage Direct Current Transmission

    Directory of Open Access Journals (Sweden)

    Yong Chen

    2016-01-01

    Full Text Available The Modular Multilevel Converters (MMC have been a spotlight for the high voltage and high power transmission systems. In the VSC-HVDC (High Voltage Direct Current based on Voltage Source Converter transmission system, the energy of DC link is stored in the distributed capacitors, and the difference of capacitors in parameters and charge rates causes capacitor voltage balance which affects the safety and stability of HVDC system. A method of MMC based on the expert system for reducing the frequency of the submodules (SMs of the IGBT switching frequency is proposed. Firstly, MMC with 51 levels for HVDC is designed. Secondly, the nearest level control (NLC for 51-level MMC is introduced. Thirdly, a modified capacitor voltage balancing method based on expert system for MMC-based HVDC transmission system is proposed. Finally, a simulation platform for 51-level Modular Multilevel Converter is constructed by using MATLAB/SIMULINK. The results indicate that the strategy proposed reduces the switching frequency on the premise of keeping submodule voltage basically identical, which greatly reduces the power losses for MMC-HVDC system.

  10. ENEL high and medium voltage electrical substations for power supply to urban centers

    International Nuclear Information System (INIS)

    Bargigia, A.; Boatto, C.; Di Mario, A.; Fava, N.; Sciarra, S.; Speziali, R.

    1991-12-01

    Modular high and medium voltage gas insulated electrical substations are being used by ENEL (Italian Electricity Board) to meet the specific needs of urban centers with special design and sizing constraints of a historical/architectural nature. This paper illustrates the key design, construction operation and performance characteristics of these standardized units. The descriptions include brief notes on equipment-transformer interconnection, interchangeability and environmental compatibility. Performance test procedures and results of actual reliability and certification tests on some substations are reported

  11. Analysis of Back-to-Back MMC for Medium Voltage Applications under Faulted Condition

    DEFF Research Database (Denmark)

    Bose, Anurag; Martins, Joäo Pedro Rodrigues; Chaudhary, Sanjay K.

    2017-01-01

    This paper analyzes a 10MW medium voltage Back-to-Back (BTB) Modular Multilevel Converter (MMC) without a DC-Link capacitor with halfbridge submodules. It focusses on the system behavior under single-line-to-ground (SLG) fault when there is no capacitor on the DC-Link.The fault current is computed...... to prevent DC overvoltages in the sub-modules during faults....

  12. Dynamic Stability Analysis of Autonomous Medium-Voltage Mixed-Source Microgrid

    DEFF Research Database (Denmark)

    Zhao, Zhuoli; Yang, Ping; Guerrero, Josep M.

    2015-01-01

    In an autonomous microgrid without connection to the interconnected grid to support the frequency and voltage, it is more complex to control and manage. Thus in order to investigate the dynamic stability of the medium-voltage (MV) microgrid in Dongao Island, a detailed small-signal state......-space model of the autonomous MV mixed-source microgrid containing diesel generator set (DGS), grid-supporting battery energy storage system (BESS), squirrel cage induction generator (SCIG) wind turbine and network is developed. Sensitivity analysis is carried out to reveal the dynamic stability margin...... of the MV microgrid and identify the permissible variations range of the droop coefficients. Finally, the theoretical analysis is verified with time-domain simulation and experimental results....

  13. Potentially damaging failure modes of high- and medium-voltage electrical equipment

    International Nuclear Information System (INIS)

    Hoy, H.C.

    1984-01-01

    The high- and medium-voltage electrical equipment failures of both nuclear and nonnuclear electric utilities have been reviewed for possible disruptive failure modes that would be of special concern in a nuclear power plant. The resulting emphasis was on the electrical faults of transformers, switchgear (circuit breakers), lightning (surge) arrestors, high-voltage cabling and buswork, control boards, and other electrical equipment that, through failure, can be the initiating event that may expand the original fault to nearby or associated equipment. Many failures of such equipment were found and documented, although the failure rate of electrical equipment in utilities is historically quite low. Nuclear plants record too few failures to be statistically valid, but failures that have been recorded show that good design usually restricts the failure to a single piece of equipment. Conclusions and recommendations pertaining to the design, maintenance, and operation of the affected electrical equipment are presented

  14. High power, medium voltage, series resonant converter for DC wind turbines

    DEFF Research Database (Denmark)

    Dincan, Catalin Gabriel; Kjær, Philip Carne; Chen, Yu-Hsing

    2018-01-01

    , and the resulting compact and efficient transformer, and soft-commutated inverter, present particular advantages in high-power, high-voltage applications, like DC offshore wind turbines. With transformer excitation frequency in hundreds of Hz range, line-frequency diodes can be employed in the high......A new modulation scheme is introduced for a single-phase series-resonant converter, which permits continuous regulation of power from nominal level to zero, in presence of variable input and output dc voltage levels. Rearranging the circuit to locate the resonant LC tank on the rectifier side...

  15. Abatement cost of SF6 emissions from medium voltage switchgear. Validation of recent studies for the European Commission

    Energy Technology Data Exchange (ETDEWEB)

    Benner, J.; Van Lieshout, M.; Croezen, H.

    2012-05-15

    Sulphur hexafluoride (SF6) is a gas with applications including use as an insulator and switching medium in medium voltage (MV) switchgear. While having certain unique properties, it is also a greenhouse gas, with a 22,800 times greater impact than CO2 and an atmospheric lifetime of over 3,000 years. Although the use of SF6 in MV switchgear can be avoided, according to recent studies for the European Commission, the abatement costs are high. This study validates the calculated cost levels as well as the general feasibility of determining a fixed cost figure for this purpose. This analysis yields a result which differs from the earlier studies, particularly with respect to the cost aspect, but also in other areas. CE Delft concludes that for the majority of applications cost-effective SF6-free options are available, leading to abatement costs for the use of SF6 in MV switchgear that range from - 40 to 0 euro/tCO2 eq., for all types of switchgear, with voltage levels below 25 kV and situated on relatively dry locations.

  16. Design and power management of an offshore medium voltage DC microgrid realized through high voltage power electronics technologies and control

    Science.gov (United States)

    Grainger, Brandon Michael

    The growth in the electric power industry's portfolio of Direct Current (DC) based generation and loads have captured the attention of many leading research institutions. Opportunities for using DC based systems have been explored in electric ship design and have been a proven, reliable solution for transmitting bulk power onshore and offshore. To integrate many of the renewable resources into our existing AC grid, a number of power conversions through power electronics are required to condition the equipment for direct connection. Within the power conversion stages, there is always a requirement to convert to or from DC. The AC microgrid is a conceptual solution proposed for integrating various types of renewable generation resources. The fundamental microgrid requirements include the capability of operating in islanding mode and/or grid connected modes. The technical challenges associated with microgrids include (1) operation modes and transitions that comply with IEEE1547 without extensive custom engineering and (2) control architecture and communication. The Medium Voltage DC (MVDC) architecture, explored by the University of Pittsburgh, can be visualized as a special type of DC microgrid. This dissertation is multi-faceted, focused on many design aspects of an offshore DC microgrid. The focal points of the discussion are focused on optimized high power, high frequency magnetic material performance in electric machines, transformers, and DC/DC power converters---all components found within offshore, power system architectures. A new controller design based upon model reference control is proposed and shown to stabilize the electric motor drives (modeled as constant power loads), which serve as the largest power consuming entities in the microgrid. The design and simulation of a state-of-the-art multilevel converter for High Voltage DC (HVDC) is discussed and a component sensitivity analysis on fault current peaks is explored. A power management routine is

  17. Multiple-Time-Scales Hierarchical Frequency Stability Control Strategy of Medium-Voltage Isolated Microgrid

    DEFF Research Database (Denmark)

    Zhao, Zhuoli; Yang, Ping; Guerrero, Josep M.

    2016-01-01

    In this paper, an islanded medium-voltage (MV) microgrid placed in Dongao Island is presented, which integrates renewable-energy-based distributed generations (DGs), energy storage system (ESS), and local loads. In an isolated microgrid without connection to the main grid to support the frequency....... In this way, dynamic stability control that cope with disturbances in short-time scale is implemented by microgrid central controller (MGCC) within Zone B and Zone C. Meanwhile, steady-state stability control to solve the peaks and valleys problem of loads and DGs in long-time scale is executed by microgrid...... energy management system (MEMS) within Zone A. Furthermore, based on the developed complete small-signal state-space model, sensitivity analysis of the eigenvalues is conducted in order to reveal the dynamic stability margin of the MV microgrid, and to identify the proper range of the control parameters...

  18. Requirements on medium-voltage switchgear for traction power supply; Anforderungen an Mittelspannungsschaltanlagen zur Bahnenergieversorgung

    Energy Technology Data Exchange (ETDEWEB)

    Girbert, K.H.; Loenard, D.; Northe, J. [Balfour Beatty Rail GmbH Power Systems, Offenbach (Germany)

    2003-10-01

    Differing requirements to be met by medium-voltage switchgear in conjunction with historical developments, applicable standards and regulations and customers' conditions of operation were the factors responsible for the use of open-air switchgear in outdoor and air-insulated and gas-insulated equipment in indoor environments. The requirements made today on single-phase equipment and two-phase equipment for feeding autotransformer systems are described. Priority focus in the article is given to 25 kV 50 Hz applications though the information applies to 1 AC 15 kV 16.7 Hz equipment in principle as well. The equipment is compared with that used for d.c. railways and public power supply systems. (orig.)

  19. Electric Field Simulations and Analysis for High Voltage High Power Medium Frequency Transformer

    Directory of Open Access Journals (Sweden)

    Pei Huang

    2017-03-01

    Full Text Available The electronic power transformer (EPT raises concerns for its notable size and volume reduction compared with traditional line frequency transformers. Medium frequency transformers (MFTs are important components in high voltage and high power energy conversion systems such as EPTs. High voltage and high power make the reliable insulation design of MFT more difficult. In this paper, the influence of wire type and interleaved winding structure on the electric field distribution of MFT is discussed in detail. The electric field distributions for six kinds of typical non-interleaved windings with different wire types are researched using a 2-D finite element method (FEM. The electric field distributions for one non-interleaved winding and two interleaved windings are also studied using 2-D FEM. Furthermore, the maximum electric field intensities are obtained and compared. The results show that, in this case study, compared with foil conductor, smaller maximum electric field intensity can be achieved using litz wire in secondary winding. Besides, interleaving can increase the maximum electric field intensity when insulation distance is constant. The proposed method of studying the electric field distribution and analysis results are expected to make a contribution to the improvement of electric field distribution in transformers.

  20. Control of a three-stage medium voltage solid-state transformer

    Directory of Open Access Journals (Sweden)

    Claudio Busada

    2017-12-01

    Full Text Available This paper proposes the modeling and control of a Solid-State Transformer using a three-stage conversion topology. First, a rectification stage is used, where a three-phase high-voltage AC signal is converted to a DC level; this stage is then followed by a DC-DC converter, and finally an inverter is used to convert the DC into a three-phase low-voltage AC signal. The adopted topology is modeled using a simplified model for each stage, useful to design their controllers. Based on these models, the controllers are tuned to obtain a good performance to sudden load changes. This performance is tested through simulations.

  1. Characteristics of voltage regulators with serial NPN transistor in the fields of medium and high energy photons

    International Nuclear Information System (INIS)

    Vukic, V.; Osmokrovic, P.

    2007-01-01

    Variation of collector - emitter dropout voltage on serial transistors of voltage regulators LM2990T-5 and LT1086CT5 were used as the parameter for detection of examined devices' radiation hardness in X and ? radiation fields. Biased voltage regulators with serial super-β transistor in the medium dose rate X radiation field had significantly different response from devices with conventional serial NPN transistor. Although unbiased components suffered greater damage in most cases, complete device failure happened only among the biased components with serial super-β transistor in Bremsstrahlung field. Mechanisms of transistors degradation in ionizing radiation fields were analysed [sr

  2. Five Level Laboratory var Compensator With Separated Floating DC Voltages

    DEFF Research Database (Denmark)

    Rasmussen, Tonny Wederberg

    1997-01-01

    The paper discuss a IGBT model of a 10kvar five level non clamped compensator build to in-vestigate principles about multilevel system. Pulse wide modulation with selective harmonic elimination for multilevel converter is described where one of the solution is made in the labo-ratory model. Also...... the DC voltage sharing between the capacitors from the model is shown and methods for this regulation is given....

  3. Modeling and detection of high Impedance arcing fault in medium voltage networks

    Energy Technology Data Exchange (ETDEWEB)

    Elkalashy, N.I.

    2007-07-01

    In this dissertation, a universal arc representation using the Electromagnetic Transient Program (Emp) is first developed. It is accomplished based on the bilateral interaction between Emp network and Transient Analysis Control System (Tacks) field. This arc modeling procedure is used as a useful guide to present a new model for high impedance arcing faults due to leaning trees. At the Power Systems and High Voltage Laboratory, Helsinki University of Technology (TKK), Finland, experiments have been performed to measure the fault characteristics due to leaning trees and therefore to verify the proposed model. Towards investigating detection facilities of this fault type, the fault model is incorporated at different locations in 20 kV Medium Voltage (MV) networks using the ATP draw program, which is a graphical interface utilized to simplify the ATP/Emp processing. Then, phase quantities and residual components are taken at different measuring nodes in the simulated networks. It is revealed that the main feature of this fault type that can enhance its detection is the periodicity of electromagnetic transients created by repetitions of the arc-reignition after each current zero-crossing. This feature is obtained considering different earthing concepts. Different detection techniques are proposed based on Discrete Wavelet Transform (DWT). The absolute sum of the wavelet coefficients in the respective frequency band is investigated for the detection purposes while several selectivity functions are proposed for the first time. The selectivity functions are presented using Logic Functions, fundamental current components and transient power directionalities. Test cases provide evidence of the efficacy of the proposed techniques. This dissertation is written in a form of the article dissertation. Its core depends on both of a summary and six original publications. (orig.)

  4. Modeling and experimental investigation of lightning arcs and overvoltages for medium voltage distribution lines

    Energy Technology Data Exchange (ETDEWEB)

    Omidiora, M. A.

    2011-07-01

    In this dissertation, lightning overvoltages in Medium Voltage (MV) lines are thoroughly investigated. The other goal is to propose new protection schemes for the designs. The lines consist of overhead lines, underground cables and covered conductors. These overvoltage problems range from direct and indirect strokes to lightning arcs. All the models and simulations are developed using the Electromagnetic Transient Program (EMTP) and Finite Element Method (FEM), while MATLAB is used for post-processing the results and identification of the model parameters. Improvement in the surge protection of MV overhead lines is demonstrated with a combination of surge arresters and a shield wire. Using the IEEE 34-node feeder injected with multiple lightning strokes, the feeder is simulated using EMTP. The response of the line is modeled both with and without the surge protection devices. The simulation study extends to the performance of a MV underground cable due to a nearby lightning discharge using FEM. The use of shield wire for limiting the overvoltage stress in the cables is proposed. A numerical analysis and simulations are performed to determine the outage rate of MV covered conductors due to lightning strokes of different characteristics. The optimum distance for surge protective devices on the conductors is also assessed. An enhancement in the surge analysis of distribution lines with the shielding effect of trees is proposed. An experimental study shows that a tree can intercept a lightning stroke in the vicinity of a distribution line. This study also analyzes experimental results of the shielding effectiveness of a tree and the induced voltages existing between the tree and the distribution line. The study is extended to evaluate the induced voltage on a distribution line for larger clearances using a Rusck model. This work investigates the lightning arc between an overhead line and a nearby tree under artificial rainfall. A full-scale laboratory experiment

  5. A new Zero Voltage Switching three-level NPC inverter

    DEFF Research Database (Denmark)

    He, Ning; Chen, Yenan; Xu, Dehong

    2015-01-01

    A novel Zero Voltage Switching (ZVS) three-level NPC inverter topology using a new ZVS Space Vector Modulation (SVM) scheme is proposed. A detailed operation analysis of ZVS three-level NPC inverter is given. The ZVS condition of the proposed ZVS inverter is derived and it can be achieved of all...... switches in the proposed inverter, which include both the main switches and the auxiliary switches. The design of resonant circuits parameters is also provided. Finally the proposed circuit and ZVS SVM scheme are verified by experimental results and demonstrate a superior performance....

  6. Calculation of pressure and temperature in medium-voltage electrical installations due to fault arcs

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X; Gockenbach, E [Institute of Electric Power Systems, Division of High Voltage Engineering, Leibniz University of Hanover, Hanover, 30167 Germany (Germany); Zhang, J [SIEMENS High Voltage Circuit Breaker Ltd Co., Hangzhou, 310018 (China)], E-mail: zhang@si.uni-hannover.de

    2008-05-21

    In order to determine the pressure rise due to arc faults in electrical installations, the portion of energy heating the surrounding gas of fault arcs has to be known. The ratio of the portion of energy to the electric energy, the thermal transfer coefficient, is adopted as the k{sub p} factor. This paper presents a theoretical approach for the determination of the thermal transfer coefficient and the pressure rise in electrical installations. It is based on the fundamental hydro- and thermodynamic conservation equations and the equation of gas state taking into account melting and evaporation of metals as well as chemical reactions with the surrounding gas. In order to consider the dependence of the arc energy on the gas density, the radiative effect of fault arcs on the energy balance is introduced into the arc model by using the net emission coefficient as a function of gas density, arc temperature and arc radius. The results for a test container show that factors such as the kinds of insulating gases and of electrode materials, the size of test vessels and the gas density considerably influence the thermal transfer coefficient and thus the pressure rise. Furthermore, it is demonstrated, for an example of the arc fault in a compact medium-voltage station with pressure relief openings and a pressure relief channel, that the arc energy and the arc temperature can be simulated based on the changing gas density.

  7. Simulation of a Narrowband Power Line Communications System over Medium Voltage

    Directory of Open Access Journals (Sweden)

    Nikolaos Chiotellis

    2016-03-01

    Full Text Available Narrowband Power Line Communications (NB-PLCs are investigated as an alternative option for transferring low rate smart grid (SG data via Medium Voltage (MV power lines. In this framework, two variants of orthogonal frequency division multiplexing are examined, namely Filtered-OFDM (F-OFDM and Wavelet-OFDM (W-OFDM, in an attempt to determine which of them is capable of transmitting low rate SG data to greater distances over non-branched MV power lines. The reach of NB-PLC signals via MV power lines is estimated, taking into account the transfer function of the relevant PLC channels and noise mechanisms as well as the specific features of the two modulation options under consideration. Simulations show that NB-PLC transmission constitutes a technically feasible and economically affordable option for exchanging low rate data with remote SG nodes dispersed over the MV grid. Moreover, simulations show that F-OFDM allows low rate data transmission to considerably greater distances compared to W-OFDM.

  8. Trends in medium-voltage switchgear products; Chuatsu switchgear no seihin doko

    Energy Technology Data Exchange (ETDEWEB)

    Nagata, T.; Miyagawa, M.; Oishi, M. [Toshiba Corp., Tokyo (Japan)

    1996-08-01

    Concerning the medium-voltage switchgear that is a main component of a power supply facility, there is a demand for the enhancement of space-saving, maintenance-free, high-reliability, and safety-related features. Introduced in this report, with reference being taken to recent trends, is the series of products manufactured by Toshiba Corporation that has been making efforts for the development of technologies integration, insulation technology, and connection of the switchgear to the equipment, which are all for the satisfaction of the above-mentioned needs. When the technological trend is considered, it is to be stated that apparatuses and devices provided in the past with a single purpose have come to be integrated into one unit for composite function and reduction in size. Examples are the BCT in which a bushing and the current transformer used for an instrument are integrated and the truck-type breaker in which the breaker is provided with a disconnecting function. Other examples include the composite insulation method in which an insulation coating is provided on and a barrier is inserted into an electrode and the method of adjusting the contact surface pressure between different materials in connecting the terminals to appliances and devices, both using gaseous insulation that is higher in the degree of freedom in structuring. Further development in this field is expected to involve a hermetic type switchgear. 4 refs., 11 figs., 3 tabs.

  9. Performance analysis of the PLC (Power Line Communication) in medium voltage electrical networks; Analise de desempenho de sistemas PLC em redes eletricas de media tensao

    Energy Technology Data Exchange (ETDEWEB)

    Mota, A.A.; Paleta, R. [Pontificia Universidade Catolica de Campinas (PUC-Campinas), SP (Brazil)], E-mail: amota@puc-campinas.edu.br; Mota, L.T.M.; Ricardo, R.A. [Indelmatec Engenharia, Campinas, SP (Brazil)], E-mail: mota@indelmatec.com.br

    2009-07-01

    Nowadays, the information access in communication networks is widely explored due to the increase of Internet users. In this context, the PLC (Power Line Communication) technology is an alternative for data transmission. This technology is based on the usage of transmission/distribution power lines for data transmission. However there are some problems related to the usage of this technology: adequate data transmission rates and generation of acceptable levels of electromagnetic interference (EMI). This work had the objective of studying the performance of PLC systems in medium voltage electrical networks, through the assess of data transmission rates and the generated EMI. Tests were carried out in a test field that corresponded to a medium voltage electrical network and the obtained results show that, under some circumstances, the PLC system does not reach the existent technical recommendations. (author)

  10. Decentralized energy management strategy based on predictive controllers for a medium voltage direct current photovoltaic electric vehicle charging station

    International Nuclear Information System (INIS)

    Torreglosa, Juan P.; García-Triviño, Pablo; Fernández-Ramirez, Luis M.; Jurado, Francisco

    2016-01-01

    Highlights: • Electric vehicle charging station supplied by photovoltaic, batteries and grid connection is analyzed. • The bus voltage is the key parameter for controlling the system by decentralized approach. • Decentralized control approach facilities the enlargement of the system. • Photovoltaic and battery systems are controlled by model predictive controllers. • Response by model predictive controllers improves that by PI controllers. - Abstract: The use of distributed charging stations based on renewable energy sources for electric vehicles has increased in recent years. Combining photovoltaic solar energy and batteries as energy storage system, directly tied into a medium voltage direct current bus, and with the grid support, results to be an interesting option for improving the operation and efficiency of electric vehicle charging stations. In this paper, an electric vehicle charging station supplied by photovoltaic solar panels, batteries and with grid connection is analysed and evaluated. A decentralized energy management system is developed for regulating the energy flow among the photovoltaic system, the battery and the grid in order to achieve the efficient charging of electric vehicles. The medium voltage direct current bus voltage is the key parameter for controlling the system. The battery is controlled by a model predictive controller in order to keep the bus voltage at its reference value. Depending on the state-of-charge of the battery and the bus voltage, the photovoltaic system can work at maximum power point tracking mode or at bus voltage sustaining mode, or even the grid support can be needed. The results demonstrate the proper operation and energy management of the electric vehicle charging station under study.

  11. Huggable communication medium decreases cortisol levels

    Science.gov (United States)

    Sumioka, Hidenobu; Nakae, Aya; Kanai, Ryota; Ishiguro, Hiroshi

    2013-01-01

    Interpersonal touch is a fundamental component of social interactions because it can mitigate physical and psychological distress. To reproduce the psychological and physiological effects associated with interpersonal touch, interest is growing in introducing tactile sensations to communication devices. However, it remains unknown whether physical contact with such devices can produce objectively measurable endocrine effects like real interpersonal touching can. We directly tested this possibility by examining changes in stress hormone cortisol before and after a conversation with a huggable communication device. Participants had 15-minute conversations with a remote partner that was carried out either with a huggable human-shaped device or with a mobile phone. Our experiment revealed significant reduction in the cortisol levels for those who had conversations with the huggable device. Our approach to evaluate communication media with biological markers suggests new design directions for interpersonal communication media to improve social support systems in modern highly networked societies. PMID:24150186

  12. Huggable communication medium decreases cortisol levels.

    Science.gov (United States)

    Sumioka, Hidenobu; Nakae, Aya; Kanai, Ryota; Ishiguro, Hiroshi

    2013-10-23

    Interpersonal touch is a fundamental component of social interactions because it can mitigate physical and psychological distress. To reproduce the psychological and physiological effects associated with interpersonal touch, interest is growing in introducing tactile sensations to communication devices. However, it remains unknown whether physical contact with such devices can produce objectively measurable endocrine effects like real interpersonal touching can. We directly tested this possibility by examining changes in stress hormone cortisol before and after a conversation with a huggable communication device. Participants had 15-minute conversations with a remote partner that was carried out either with a huggable human-shaped device or with a mobile phone. Our experiment revealed significant reduction in the cortisol levels for those who had conversations with the huggable device. Our approach to evaluate communication media with biological markers suggests new design directions for interpersonal communication media to improve social support systems in modern highly networked societies.

  13. Using the Direct Search Method for Optimal Dispatch of Distributed Generation in a Medium-Voltage Microgrid

    Directory of Open Access Journals (Sweden)

    Wei-Tzer Huang

    2014-12-01

    Full Text Available This paper proposes a simple and efficient approach for the optimal dispatch in a medium-voltage microgrid (MG with various types of distributed generation (DG. The fuel costs generated by these DGs are determined using quadratic and linear functions dependent on the types of DGs. Instead of using the traditional Lagrange multiplier method for power system economic dispatch, the proposed direct search method (DSM approach is able to handle several inequality constraints without introducing any multipliers and furthermore it can solve the non-derivative problems or the fuel cost functions being much more complicated. Accordingly, the DSM is proposed for determining the optimal dispatch of MGs with various types of DG to minimize generation costs under grid-tied and autonomous operations. Results demonstrate that the proposed DSM is a highly suitable and simple approach to determining the optimal dispatch in medium-voltage MGs with various types of DG.

  14. Application of higher harmonics in protection against single-phase earth faults in resonant grounded cable networks of medium voltage

    OpenAIRE

    Vinokurova, T. Yu.; Dobryagina, O. A.; Shagurina, E. S.; Shuin, V. A.

    2015-01-01

    Protections based by higher harmonics absolute measurements the zero sequence currents of the protected object connections against single-phase earth faults in resonant grounded cable networks of medium voltage industrial and urban energy supply systems have been widely applied in Russia since the late 60s of the 20th century. However, some operational problems connected with sufficient selectivity and sensitivity of these protection devices appeared with time. Sensitivity and selectivity of ...

  15. Modularized Three-Phase Semiconductor Transformer with Bidirectional Power Flow for Medium Voltage Application

    Directory of Open Access Journals (Sweden)

    Do-Hyun Kim

    2016-08-01

    Full Text Available This paper describes a prototype of modularized three-phase semiconductor transformer that was developed in the lab for feasibility study. The developed prototype is composed of three units of single-phase semiconductor transformer coupled in Y-connection. Each single-phase unit has multiple units of high-voltage high-frequency resonant AC–DC converter, a low-voltage hybrid-switching DC–DC converter, and a low-voltage hybrid-switching DC–AC inverter. Also, each single-phase unit has two digital signal processor (DSP boards to control converter operation and to acquire monitoring data. The monitoring system was developed based on LabView by using controller area network (CAN communication between the DSP board and the personal computer (PC. Through diverse experimental analyses it was verified that the prototype operates with proper performance under normal and sag conditions. The developed prototype confirms the possibility of fabricating a commercial high-voltage high-power semiconductor transformer by increasing the number of series-connected converter modules in high-voltage side and improving the system efficiency with a new switching device such as an SiC device.

  16. A Medium-Voltage Motor Drive with a Modular Multilevel PWM Inverter Part II. Startup Method and Performance

    Science.gov (United States)

    Nishimura, Kazutoshi; Hagiwara, Makoto; Akagi, Hirofumi

    This paper presents a medium-voltage motor drive with a modular multilevel PWM inverter, and focuses on a startup method and its performance. It is formed by six modular arms, each of which consists of a cascaded stack of multiple bidirectional chopper-cells. The frequency of the dominant ac-voltage fluctuation is equal to the motor (inverter) frequency. These fluctuations occur in the dc capacitor of each chopper-cell, and the magnitude of the fluctuation is inversely proportional to the motor frequency. Because of the increased voltage fluctuation in low-frequency regions, the so-called “volt-per-hertz control” cannot be applied in motor starting. The startup method proposed in this paper is suitable for a motor drive with the modular multilevel PWM inverter. It enables the motor to produce a startup torque loaded on the motor at an initial amplitude and a fixed frequency of the inverter while taking into account constraints on the motor current and the ac-voltage fluctuation. The validity of the startup method as well as the startup performance is confirmed by experiment and simulation.

  17. Assessing Losses of Power and Electrical Energy in Unbalanced Medium Voltage Distribution Networks

    Directory of Open Access Journals (Sweden)

    Toader C.

    2016-12-01

    Full Text Available The work is dedicated to calculating electricity losses related to power lines average voltage overhead or underground, which in terms of construction can be three-phase (three or four wire in unbalanced sinusoidal harmonic, determining energy efficiency indicators (such as positive and negative factors of unbalance thereof. It examines a case study and argues the results.

  18. Characteristics of plasma in culture medium generated by positive pulse voltage and effects of organic compounds on its characteristics

    Science.gov (United States)

    Sato, Y.; Sato, T.; Yoshino, D.

    2016-12-01

    We describe a positive pulse voltage method for generating plasma in culture medium with a composition similar to biological fluids. We also describe the plasma’s characteristics, liquid quality, and the effect of organic compounds in the culture medium on the plasma characteristics through comparisons to a solution containing inorganic salts at the same concentrations as in the culture medium. Light emission with Na and OH spectra was observed within a vapor bubble produced by Joule heating at the tip of the electrode. A downward thermal flow and shock wave were caused by the behavior of the vapor bubble. The culture medium pH gradually increased from 7.9 to 8.3 over the discharge time of 300 s. H2O2 was generated 1.1 mg l-1 in the culture medium after discharge for 300 s, and this value was 0.5 mg l-1 lower than the inorganic salts solution which does not contain organic compounds. This study provides important data that will help facilitate more widespread application of plasma medicine.

  19. Diagnostics and LIFE-cycle assessment of medium-voltage cables in nuclear power plants during regular overhaul process

    International Nuclear Information System (INIS)

    Podkoritnik, Simon; Jansa, Marko; Manojlovic, Stanko

    2015-01-01

    The reliability of operation of a nuclear power plant substantially depends on the reliability of its individual components. Electric cables, particularly medium-voltage cables represent an important constituent of the nuclear island as well as of the balance of plant. It can't be considered as satisfactory that the redundancy of a particular subsystem is ensured. For this purpose it is important to check the cable insulation condition, which is supposed to be carried out during the overhaul activities. The lifetime of medium-voltage cables is estimated to attain somewhere around 40 years. However, due to electrical, thermal and mechanical stresses it may be significantly reduced. In order to avoid its likely failures and following outages the insulation must be tested regularly. Based on obtained testing results the condition of a cable or cable termination can be assessed and repair or replacement made, if necessary. The article presents some of most important non-destructive diagnostic measurements on cable connections recommended to be done during the overhaul of a nuclear power plant following a good practice of asset maintenance management. (author)

  20. Novel methods for earth fault management in medium voltage distribution networks

    Energy Technology Data Exchange (ETDEWEB)

    Nikander, A.; Jaerventausta, P. [Tampere Univ. of Technology (Finland)

    1998-08-01

    Customers have become less and less tolerable against even short interruptions of supply. Rapid autoreclosures are especially harmful for those commercial and private customers who have equipment which will be disturbed by these under half second interruptions. Mainly due to increasing use of distribution automation (eg. remote controlled switching devices, fault detectors, computational fault location) the average interruption period per customer has been reduced. Simultaneously the amount of equipment sensitive to short voltage break or dip has increased. Therefore reducing the number of the interruptions has become a more essential target

  1. Evaluation of Conservation Voltage Reduction (CVR) on a National Level

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, Kevin P.; Fuller, Jason C.; Tuffner, Francis K.; Singh, Ruchi

    2010-09-29

    Conservation Voltage Reduction (CVR) is a reduction of energy consumption resulting from a reduction of feeder voltage. While there have been numerous CVR systems deployed in North America there has been little substantive analytic analysis of the effect; the majority of the published results are based on empirical field measurements. Since these results are based on empirical measurements it is difficult to extrapolate how this technology will behave on the various types of distribution feeders found throughout the nation. This report has utilized the Taxonomy of Prototypical feeder developed under the Modern Grid Initiative (MGI), now the Modern Grid Strategy (MGS), in order to estimate the benefits of CVR on multiple distribution feeder types. This information will then be used to determine an estimate of the national benefits of a wide scale deployment of CVR.

  2. A generalized discontinuous PWM based neutral point voltage balancing method for three-level NPC voltage source inverter with switching losses reduction

    DEFF Research Database (Denmark)

    Li, Kai; Wei, Min; Xie, Chuan

    2017-01-01

    In order to control the neutral point voltage of inverter with discontinuous PWM (DPWM), this paper proposed a generalized discontinuous PWM (GDPWM) based neutral point voltage balancing method for three level neutral point clamped (NPC) voltage source inverter (VSI). Firstly, a triangle carrier ...

  3. Harmonic elimination technique for a single-phase multilevel converter with unequal DC link voltage levels

    DEFF Research Database (Denmark)

    Ghasemi, N.; Zare, F.; Boora, A.A.

    2012-01-01

    modulation and harmonic elimination (HE) methods. Multilevel converters may have a DC link with equal or unequal DC voltages. In this study a new HE technique based on the HE method is proposed for multilevel converters with unequal DC link voltage. The DC link voltage levels are considered as additional...... on the output voltage quality by reducing its total harmonic distortion, which must take into consideration for some applications such as uninterruptable power supply, motor drive systems and piezoelectric transducer excitation. In order to verify the proposed modulation technique, MATLAB simulations...

  4. An interleaved five-level boost converter with voltage-balance control

    DEFF Research Database (Denmark)

    Chen, Jianfei; Hou, Shiying; Deng, Fujin

    2016-01-01

    This paper proposes an interleaved five-level boost converter based on switched-capacitor network. Operating principle of the converter under CCM mode is analyzed. High voltage gain, low component stress, small input current ripple, and self-balance function for capacitor voltages in the switched-capacitor...

  5. Five-Level Converter with Low Switching Frequency Applied as DC Voltage Supply

    DEFF Research Database (Denmark)

    Rasmussen, Tonny Wederberg

    1999-01-01

    This paper describes the use of a multi-level converter as a DC supply. Equations for the converter will be deduced in the nondissipative case. The equations provide solutions to DC voltage and the angle of converter voltage. In addition the spectrum for the harmonics after the elimination...... of selected harmonics will be shown. Finally measurements on a practical laboratory model are shown....

  6. Effect of mix proportions, seawater curing medium and applied voltages on corrosion resistance of concrete incorporating mineral admixtures

    Directory of Open Access Journals (Sweden)

    Ahmed M. Diab

    2011-03-01

    Full Text Available Most reinforced concrete structures suffer durability problems during their service. The major durability problem is the corrosion of reinforcing steel which results in cracking and spalling of concrete. Nowadays, mineral admixtures, such as silica fume and metakaolin are used to enhance the corrosion resistance of reinforced concrete structures. In this research work, accelerated corrosion tests were carried out on reinforced concrete specimens made with plain, silica fume and metakaolin blended cements. The mineral admixtures were incorporated in the mixtures as a partial replacement by weight. The replacement percentages were 10%, 15%, and 25% of cement content by weight. Three types of cement were used in the program which were type I, type II, and type V Portland cement as classified by ASTM C150. Cement content of 350 and 450 kg/m3 were used in concrete mixes with 0.40 and 0.50 water-binder ratios (w/cm. The curing mediums of specimens were potable water and seawater medium. Also, the effect of applied voltage on the accelerated test was studied. The current intensity, visible cracking time, and critical time up to 2 mm crack width were recorded during testing. The weight loss of the steel was also determined after testing. The observed superior resistance performance of silica fume and metakaolin blended cement concrete as compared to plain cement concrete in terms of cracking time, critical time, weight loss, and corrosion intendancy factor was monitored. Also, concrete mixes made with type I Portland cement have a good corrosion resistance compared with that of type II and type V Portland cement concrete mixes both cured in potable water and sea water medium.

  7. The low and medium level solid radioactive wastes

    International Nuclear Information System (INIS)

    1981-01-01

    One of the most controversial aspects in the nuclear energy utilization for pacific purposes is related with the low and medium level solid radioactive wastes production, during the nuclear power plants operation. These wastes shall be inmobilizated before their storage on-site or their transport out-site. This paper presents an exposition about the avobe mentioned problem, attending three basic areas: the fundamental concepts and criteria for their management, the methods used in western countries and the present situation of the spanish nuclear power plants in operation and under construction. (auth.)

  8. Common voltage eliminating of SVM diode clamping three-level inverter connected to grid

    DEFF Research Database (Denmark)

    Guo, Yougui; Zeng, Ping; Zhu, Jieqiong

    2011-01-01

    three-level inverter is presented with PLECS. Finally, a series of simulations are carried out. The simulation results tell us PLECS is a very powerful tool to real power circuits modeling. They have also verified that proposed common mode voltage eliminating control strategy of SVM is feasible...... to control the diode clamping three-level inverter. But further research has to be done to get rid of the common mode voltage completely by controlling the voltages of two capacitors at the input terminal....

  9. Topology and Technology Survey on Medium Voltage Power Converters for Large Wind Turbines

    DEFF Research Database (Denmark)

    Sztykiel, Michal; Teodorescu, Remus; Munk-Nielsen, Stig

    2011-01-01

    -up transformer is permanently removed from the topology. As a result, the generator-converter circuitry operates on 20 kV level, which introduces new challenges into the design. The first part of the paper presents a system approach, in which general converter features are discussed with regard to this specific...... application. Based on obtained conclusions, the second part of the paper highlights the most promising converter topology concepts and circuitries, which can be adapted and eventually utilized. Finally, results show that the most promising topologies can be acquired from a modular approach, which is made...

  10. Medium-Level Laser in Chronic Tinnitus Treatment

    Directory of Open Access Journals (Sweden)

    K. Dejakum

    2013-01-01

    Full Text Available The purpose of this study was to evaluate the effect of medium-level laser therapy in chronic tinnitus treatment. In a prospective double-blind placebo-controlled trial, either active laser (450 mW, 830 nm combined Ga-Al-As diode laser or placebo irradiation was applied through the external acoustic meatus of the affected ear towards the cochlea. Fourty-eight patients with chronic tinnitus were studied. The main outcome was measured using the Goebel tinnitus questionnaire, visual analogue scales measuring the perceived loudness of tinnitus, the annoyance associated with tinnitus, and the degree of attention paid to tinnitus as well as psycho-acoustical matches of tinnitus pitch and loudness. The results did show only very moderate temporary improvement of tinnitus. Moreover, no statistically relevant differences between laser and placebo group could be found. We conclude that medium-level laser therapy cannot be regarded as an effective treatment of chronic tinnitus in our therapy regime considering the limited number of patients included in our study.

  11. Carrier-Based Common Mode Voltage Control Techniques in Three-Level Diode-Clamped Inverter

    Directory of Open Access Journals (Sweden)

    Pradyumn Chaturvedi

    2012-01-01

    Full Text Available Switching converters are used in electric drive applications to produce variable voltage, variable frequency supply which generates harmful large dv/dt and high-frequency common mode voltages (CMV. Multilevel inverters generate lower CMV as compared to conventional two-level inverters. This paper presents simple carrier-based technique to control the common mode voltages in multilevel inverters using different structures of sine-triangle comparison method such as phase disposition (PD, phase opposition disposition (POD by adding common mode voltage offset signal to actual reference voltage signal. This paper also presented the method to optimize the magnitude of this offset signal to reduce CMV and total harmonic distortion in inverter output voltage. The presented techniques give comparable performance as obtained in complex space vector-based control strategy, in terms of number of commutations, magnitude, and rate of change of CMV and harmonic profile of inverter output voltage. Simulation and experimental results presented confirm the effectiveness of the proposed techniques to control the common mode voltages.

  12. Methods for calculation of undelivered electricity in medium voltage network that is not integrated into the remote control system

    Directory of Open Access Journals (Sweden)

    Vrcelj Nada

    2013-01-01

    Full Text Available The method is based on data obtained from the so-called. hand-held measuring current at 10 kV voltage level and from reports of outages at reclosers that are installed in a part of network that is observed. At first, is calculates the electrical load of the main distribution power lines, and then simulates the corresponding power flow and calculates the undelivered electricity. The method was applied to parts of the network PD ED Belgrade that are not in the remote control system and is developed for the purpose of considering the effects of automation in the 10 kV PD ED Belgrade.

  13. Synchronised PWM Schemes for Three-level Inverters with Zero Common-mode Voltage

    DEFF Research Database (Denmark)

    Oleschuk, Valentin; Blaabjerg, Frede

    2002-01-01

    This paper presents results of analysis and comparison of novel synchronised schemes of pulsewidth modulation (PWM), applied to three-level voltage source inverters with control algorithms providing elimination of the common-mode voltage. The proposed approach is based on a new strategy of digital...... PWM with synchronous smooth pulses-ratio changing and a quarter-wave symmetry of the voltage waveforms. Three basic versions of both algebraic and trigonometric synchronised PWM have been analysed. Simulations give the behaviour of the proposed methods and show some advantage of synchronised PWM...

  14. Medium Range Ensembles Flood Forecasts for Community Level Applications

    Science.gov (United States)

    Fakhruddin, S.; Kawasaki, A.; Babel, M. S.; AIT

    2013-05-01

    Early warning is a key element for disaster risk reduction. In recent decades, there has been a major advancement in medium range and seasonal forecasting. These could provide a great opportunity to improve early warning systems and advisories for early action for strategic and long term planning. This could result in increasing emphasis on proactive rather than reactive management of adverse consequences of flood events. This can be also very helpful for the agricultural sector by providing a diversity of options to farmers (e.g. changing cropping pattern, planting timing, etc.). An experimental medium range (1-10 days) flood forecasting model has been developed for Bangladesh which provides 51 set of discharge ensembles forecasts of one to ten days with significant persistence and high certainty. This could help communities (i.e. farmer) for gain/lost estimation as well as crop savings. This paper describe the application of ensembles probabilistic flood forecast at the community level for differential decision making focused on agriculture. The framework allows users to interactively specify the objectives and criteria that are germane to a particular situation, and obtain the management options that are possible, and the exogenous influences that should be taken into account before planning and decision making. risk and vulnerability assessment was conducted through community consultation. The forecast lead time requirement, users' needs, impact and management options for crops, livestock and fisheries sectors were identified through focus group discussions, informal interviews and questionnaire survey.

  15. A Manufacturing Cost and Supply Chain Analysis of SiC Power Electronics Applicable to Medium-Voltage Motor Drives

    Energy Technology Data Exchange (ETDEWEB)

    Horowitz, Kelsey [National Renewable Energy Lab. (NREL), Golden, CO (United States); Remo, Timothy [National Renewable Energy Lab. (NREL), Golden, CO (United States); Reese, Samantha [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2017-03-24

    Wide bandgap (WBG) semiconductor devices are increasingly being considered for use in certain power electronics applications, where they can improve efficiency, performance, footprint, and, potentially, total system cost compared to systems using traditional silicon (Si) devices. Silicon carbide (SiC) devices in particular -- which are currently more mature than other WBG devices -- are poised for growth in the coming years. Today, the manufacturing of SiC wafers is concentrated in the United States, and chip production is split roughly equally between the United States, Japan, and Europe. Established contract manufacturers located throughout Asia typically carry out manufacturing of WBG power modules. We seek to understand how global manufacturing of SiC components may evolve over time by illustrating the regional cost drivers along the supply chain and providing an overview of other factors that influence where manufacturing is sited. We conduct this analysis for a particular case study where SiC devices are used in a medium-voltage motor drive.

  16. Organic complexing agents in low and medium level radioactive waste

    International Nuclear Information System (INIS)

    Allard, B.; Persson, G.

    1985-11-01

    Low and medium level radioactive wastes will contain various organic agents, such as ion exchange resins (mainly in the operational wastes), plastics and cellulose (mainly in the reprocessing wastes and in the decommissioning wastes) and bitumen (mainly in the reprocessing wastes). The degradation of these organics will lead to the formation of complexing agents that possibly could affect the release of radionuclides from an underground repository and the subsequent transport of these nuclides. The solution chemistry of the actinides may be totally dominated by the presence of such organic degradation products within the repository. However, hydrolysis and formation of carbonates (and possibly humates) will most likely dominate solubility and speciation outside the immediate vicinity of the repository. The minor quantities of strong complexing agents (in the reprocessing waste), notably aminopolycarboxylic acids (EDTA, DTPA) and possibly organic phosphates (DBP) could significantly affect speciation and sorption behaviour of primarily the trivalent actinides even outside the repository. (author)

  17. New developments for medium and low level waste vitrification

    International Nuclear Information System (INIS)

    Boen, A.J.-R.; Pujadas, S.M.-V.

    1997-01-01

    Converting ultimate waste material into a stable, inert product is beneficial, notably in the case of potentially very toxic wastes. Vitrification, in which a glass or glass-ceramic material is fabricated from a particular waste form, is now a proven solution. This high-temperature process uses additives-notably silica-if necessary to form a glass network. Vitrification confines the waste by forming a stable, inert, nontoxic material suitable for safe disposal; it usually also results in a significant volume reduction having a major effect on the disposal cost. France is actively engaged in an ongoing research effort in this area, not only to enhance the production capacity and the containment quality, but also to extend the process to low and medium level wastes such as those produced in nuclear power stations

  18. Simple Neutral-Point Voltage Control for Three-Level Inverters Using a Discontinuous Pulse Width Modulation

    DEFF Research Database (Denmark)

    Choi, Uimin; Lee, K.B.; Lee, Hyun-Hee

    2013-01-01

    This paper proposes a neutral-point voltage balancing method for a three-level inverter that uses discontinuous pulse width modulation (DPWM). The performance of a three-level inverter system is affected by the neutral-point voltage unbalancing. Therefore, the voltages of series connected dc......-link capacitors should be equal. Generally, the offset voltage is added to reference voltages in the conventional voltage balancing method. However, when using DPWM, the performance of conventional balancing method is limitary because turn-on and turn-off switching occurs at regular intervals. The proposed method...

  19. ELIMINATING HARMONICS IN A FIVE LEVEL INVERTER BY OPTIMIZED BOTH SWITCHING ANGLES AND DC LINK VOLTAGE

    Directory of Open Access Journals (Sweden)

    Abdal Karim Z. Mansoor

    2013-05-01

    Full Text Available This paper presents design and analysis of  a single phase multilevel inverter by optimizing  both switching angles and DC link voltage of a cascaded inverter. The switching angles and dc link voltage are chosen such that to minimize the total harmonic distortion of the output voltage. The main power devices are switched only once per cycle , so that to overcome the switching loss problem, as well as electromagnetic interference (EMI problem, a method is given to determine the optimum value of the switching angles and the value of the dc link voltage. Theoretical analysis and  simulation of a single phase 5-level cascaded inverter are introduced with a wide range of modulation index

  20. Low Wind Speed Turbine Project Phase II: The Application of Medium-Voltage Electrical Apparatus to the Class of Variable Speed Multi-Megawatt Low Wind Speed Turbines; 15 June 2004--30 April 2005

    Energy Technology Data Exchange (ETDEWEB)

    Erdman, W.; Behnke, M.

    2005-11-01

    Kilowatt ratings of modern wind turbines have progressed rapidly from 50 kW to 1,800 kW over the past 25 years, with 3.0- to 7.5-MW turbines expected in the next 5 years. The premise of this study is simple: The rapid growth of wind turbine power ratings and the corresponding growth in turbine electrical generation systems and associated controls are quickly making low-voltage (LV) electrical design approaches cost-ineffective. This report provides design detail and compares the cost of energy (COE) between commercial LV-class wind power machines and emerging medium-voltage (MV)-class multi-megawatt wind technology. The key finding is that a 2.5% reduction in the COE can be achieved by moving from LV to MV systems. This is a conservative estimate, with a 3% to 3.5% reduction believed to be attainable once purchase orders to support a 250-turbine/year production level are placed. This evaluation considers capital costs as well as installation, maintenance, and training requirements for wind turbine maintenance personnel. Subsystems investigated include the generator, pendant cables, variable-speed converter, and padmount transformer with switchgear. Both current-source and voltage-source converter/inverter MV topologies are compared against their low-voltage, voltage-source counterparts at the 3.0-, 5.0-, and 7.5-MW levels.

  1. A new high-voltage level-shifting circuit for half-bridge power ICs

    International Nuclear Information System (INIS)

    Kong Moufu; Chen Xingbi

    2013-01-01

    In order to reduce the chip area and improve the reliability of HVICs, a new high-voltage level-shifting circuit with an integrated low-voltage power supply, two PMOS active resistors and a current mirror is proposed. The integrated low-voltage power supply not only provides energy for the level-shifting circuit and the logic circuit, but also provides voltage signals for the gates and sources of the PMOS active resistors to ensure that they are normally-on. The normally-on PMOS transistors do not, therefore, need to be fabricated in the depletion process. The current mirror ensures that the level-shifting circuit has a constant current, which can reduce the process error of the high-voltage devices of the circuit. Moreover, an improved RS trigger is also proposed to improve the reliability of the circuit. The proposed level-shifting circuit is analyzed and confirmed by simulation with MEDICI, and the simulation results show that the function is achieved well. (semiconductor integrated circuits)

  2. Controlling Voltage Levels of Distribution Network-Radial Feeder after Connecting Wind Turbines to the Network

    Directory of Open Access Journals (Sweden)

    Muhammad Al Badri

    2017-11-01

    Full Text Available Several factors in power generation and supply need to be taken into account such as shortages of energy supply, system stability, and energy quality and system disruption due to network losses, industrial development and population expansion. The addition of wind turbines to the distribution network is of great benefit in providing additional power and solving these problems, but this addition is accompanied by the problem of low voltage network. This research found optimal solutions to the problem of low voltage distribution network after connecting wind turbines. The main idea of this paper is to optimize the low-voltage problem as a result of connecting the wind turbines to the "far end" of the radial feeder for a distribution network and to obtain a voltage level within an acceptable and stable range. The problem of low voltage solved by using the load-drop compensation, capacitor-bank and “doubly-fed” induction generators. The results of this study were based on the operation of the entire design of the simulation system which would be compatible with the reality of the energy flow of all network components by using the PSCAD program. The present analysis program revealed an optimum solution for the low voltage profile of the distribution network after connecting the wind turbine.

  3. Admissibility of building cost subsidy in the power grid above the low voltage level

    International Nuclear Information System (INIS)

    Foerster, Sven

    2015-01-01

    Electricity networks are essential to the provision of electrical power to businesses and individuals. In particular for manufacturing businesses a connection to the grid above the low-voltage level is often useful. Network operators demand a subsidy for the new connection and for the change to a higher network level under the auspices of construction cost. The power network market above the low-voltage level is a natural monopoly. This leaves consumers looking for a connection to the power grid with no possibility to select among different network operators. Construction cost subsidies are not regulated by law above the low voltage level. The lack of legal regulation and the natural monopoly above the low-voltage level affect the balance of power between network operators and system users. The lawfulness of the construction cost subsidies, the prerequisites for their demand and a review of the calculation models (Leistungspreismodell, 2-Ebenen-Modell) as well as a proposal for a reform of this system form the subject of this work.

  4. A Zero-Voltage Switching Control Strategy for Dual Half-Bridge Cascaded Three-Level DC/DC Converter with Balanced Capacitor Voltages

    DEFF Research Database (Denmark)

    Liu, Dong; Wang, Yanbo; Chen, Zhe

    2017-01-01

    capacitors. Therefore, the proposed control strategy can improve the converter's performances in: 1) reducing the switching losses and noises of the power switches; and 2) reducing the voltage stresses on the input capacitors. Finally, the simulation results are conducted to verify the proposed control......The input capacitor's voltages are unbalanced under the conventional control strategy in a dual half-bridge cascaded three-level (TL) DC/DC converter, which would affect the high voltage stresses on the capacitors. This paper proposes a pulse-wide modulation (PWM) strategy with two working modes...

  5. Electrooptic Methods for Measurement of Small DC Currents at High Voltage Level

    DEFF Research Database (Denmark)

    Tønnesen, Ole; Beatty, Neville; Skilbreid, Asbjørn Ottar

    1989-01-01

    collectors are connected via resistors RA and RB to the protective side of the voltage to be measured and the emitters to the negative side. The currents flowing in to the bases of the transistors are independently controlled by the light levels following on the two photodiodes PDA, PDB....

  6. Three-Level Inverters with Common-Mode Voltage Cancellation Based on Synchronous Pulsewidth Modulation

    DEFF Research Database (Denmark)

    Oleschuk, Valentin; Blaabjerg, Frede

    2002-01-01

    A novel method of direct synchronous pulse-width modulation (PWM) is disseminated to three-level voltage source inverters with control algorithms with elimination of the common-mode voltages in three-phase drive systems with PWM. It provides smooth pulses-ratio changing and a quarter-wave symmetry...... of the voltage waveforms during the whole control range including overmodulation. Continuous, discontinuous and "direct-direct" schemes of synchronous PWM with both algebraic and trigonometric control functions have been analysed and compared. Simulations give the behaviour of the proposed methods and show some...... advantages of synchronous PWM in comparison with asynchronous at low ratios between the switching frequency and fundamental frequency....

  7. Voltage-Level Selection of Future Two-Level LVdc Distribution Grids

    DEFF Research Database (Denmark)

    Diaz, Enrique Rodriguez; Chen, Fang; Quintero, Juan Carlos Vasquez

    2016-01-01

    significantly. Microgrids (MGs) come as a suitable solution for the installation of distributed sources in the low voltage grid, where most of the consumers are sparsely located. Microgrids ease the integration of distributed generators (DGs), especially renewable energy sources like solar panels and small wind...

  8. The need for a common standard for voltage levels of HVDC VSC technology

    International Nuclear Information System (INIS)

    Müller, H.K.; Torbaghan, S. Shariat; Gibescu, M.; Roggenkamp, M.M.; Meijden, M.A.M.M. van der

    2013-01-01

    The expansion of offshore wind energy as well as the increase in electricity trade between the North Sea countries leads to a growing need for additional transmission capacity. Due to the predominantly remote locations of offshore wind farms, the majority of future connections will be high-voltage direct current (HVDC) connections. In order to make the construction of offshore infrastructure more efficient, the North Sea states are currently discussing the development of a common offshore grid. Although this development still stands at the very beginning, we argue in this paper that some crucial elements should be standardized from the outset; the most important one being a common voltage level. Without such standardization, the development of a European offshore grid may be suboptimal, not cost-efficient and might even be prevented from coming into existence. We examine the technical and legal issues associated with introducing a common voltage level for the use of HVDC VSC technology, and discuss the optimal standard as well as the way in which this common standard can best be achieved. - Highlights: • We highlight the need for a common standard for HVDC VSC technology. • We outline that a standardized voltage level at ± 500 kV should be the initial focus. • We discuss the developments regarding standardization of HVDC VSC technology. • We conclude that current developments are not sufficient

  9. Population level response of downy brome to soil growing medium

    Science.gov (United States)

    Downy brome (Bromus tectorum) is the most ubiquitous exotic invasive weed in the Intermountain West. A major issue for management is the extreme generalist plastic nature of downy brome. We hypothesized that soil growing medium would effect all measured response variables representing some degree of...

  10. Self-controllable Voltage Level Technique to reduce leakage current in DRAM 4×4

    OpenAIRE

    Radha.K; M. Sowmyasri

    2016-01-01

    As the technology improved to support very large chip sizes, system designers were faced with power consumption problem and leakage current problem. CMOS technology has increased in level of importance to the point where it now clearly holds center stage as the dominant VLSI technology The present work shows the implementation of a DRAM 4×4 (dynamic random access memory) with self controllable voltage level (SVL) technique. SVL technique is leakage current reduction technique. Sim...

  11. Grid Integration of Single Stage Solar PV System using Three-level Voltage Source Converter

    Science.gov (United States)

    Hussain, Ikhlaq; Kandpal, Maulik; Singh, Bhim

    2016-08-01

    This paper presents a single stage solar PV (photovoltaic) grid integrated power generating system using a three level voltage source converter (VSC) operating at low switching frequency of 900 Hz with robust synchronizing phase locked loop (RS-PLL) based control algorithm. To track the maximum power from solar PV array, an incremental conductance algorithm is used and this maximum power is fed to the grid via three-level VSC. The use of single stage system with three level VSC offers the advantage of low switching losses and the operation at high voltages and high power which results in enhancement of power quality in the proposed system. Simulated results validate the design and control algorithm under steady state and dynamic conditions.

  12. The eGo grid model: An open-source and open-data based synthetic medium-voltage grid model for distribution power supply systems

    Science.gov (United States)

    Amme, J.; Pleßmann, G.; Bühler, J.; Hülk, L.; Kötter, E.; Schwaegerl, P.

    2018-02-01

    The increasing integration of renewable energy into the electricity supply system creates new challenges for distribution grids. The planning and operation of distribution systems requires appropriate grid models that consider the heterogeneity of existing grids. In this paper, we describe a novel method to generate synthetic medium-voltage (MV) grids, which we applied in our DIstribution Network GeneratOr (DINGO). DINGO is open-source software and uses freely available data. Medium-voltage grid topologies are synthesized based on location and electricity demand in defined demand areas. For this purpose, we use GIS data containing demand areas with high-resolution spatial data on physical properties, land use, energy, and demography. The grid topology is treated as a capacitated vehicle routing problem (CVRP) combined with a local search metaheuristics. We also consider the current planning principles for MV distribution networks, paying special attention to line congestion and voltage limit violations. In the modelling process, we included power flow calculations for validation. The resulting grid model datasets contain 3608 synthetic MV grids in high resolution, covering all of Germany and taking local characteristics into account. We compared the modelled networks with real network data. In terms of number of transformers and total cable length, we conclude that the method presented in this paper generates realistic grids that could be used to implement a cost-optimised electrical energy system.

  13. Impact-Based Electromagnetic Energy Harvester with High Output Voltage under Low-Level Excitations

    Directory of Open Access Journals (Sweden)

    Qian Luo

    2017-11-01

    Full Text Available To expand the applications of vibrational energy harvesters (VEHs as power sources of wireless sensor nodes, it is of significance to improve the scavenging efficiency for the broadband, low-frequency, and low-level vibrational energy. The output voltages of electromagnetic vibrational energy harvesters (EMVEHs are usually low, which complicates the power management circuit by an indispensable voltage boosting element. To this end, an impact-based non-resonant EMVEH mainly composed of an outer frame and an inner frame on rollers is proposed. Numerical simulations based on a mathematical model of the harvester are conducted to analyze the effects of structural parameters on the output performance. Under base excitation of 0.1 and 0.3 (where g is the gravitational acceleration, 1 g = 9.8 m · s − 2 , the experimental maximum root mean square voltages of a harvester prototype across a resistor of 11 kΩ are as high as 7.6 and 16.5 V at 6.0 and 8.5 Hz, respectively, with the maximum output powers of 5.3 and 24.8 mW, or the power densities of 54.6 and 256 μW cm−3. By using a management circuit without a voltage boosting element, a wireless sensor node driven by the prototype can measure and transmit the temperature and humidity every 20 s under base excitation of 0.1 g at 5.4 Hz.

  14. Nimbus-3 Medium-Resolution Infrared Radiometer (MRIR) Level 1 Meteorological Radiation Data V001

    Data.gov (United States)

    National Aeronautics and Space Administration — The Nimbus-3 Medium-Resolution Infrared Radiometer (MRIR) Level 1 Meteorological Radiance Data contain radiances expressed as equivalent blackbody temperatures along...

  15. 30 CFR 75.901 - Protection of low- and medium-voltage three-phase circuits used underground.

    Science.gov (United States)

    2010-07-01

    ... diesel engine powering the electrical generator must be approved under 30 CFR part 7, subpart E. (2) A... equal to the phase-to-phase voltage of the system. (b) Diesel-powered electrical generators used as an... wye-connected generator neutral and the generator frame; (see Figure I in Appendix A to subpart J of...

  16. Research on voltage characteristic of the third generation low-light-level image intensifier tube's output signal to noise ratio

    Science.gov (United States)

    Bai, Xiaofeng; Yin, Lei; Hu, Wen; Shi, Feng; Hou, Zhipeng; Shi, Hongli; He, Yingping

    2012-10-01

    Signal to noise ratio is an important parameter to evaluate the 3rd generation low-light-level image intensifier. In this article, voltage in different poles have been changed respectively, output signal to noise ratio referring to different voltages have been studied, and the relationship between each voltage and output signal to noise ratio has been analyzed. The study results show that voltage of photocathode is not less than 150 V, voltage of MCP is between 800 V and 900 V, and voltage of screen is between 5000 V and 6000 V while output signal to noise ratio of filmed image intensifier is optimized. The study in this article is worthwhile for developing signal to noise ratio of the 3rd low-light-level image intensifier sufficiently.

  17. submitter Development of a 100 kW, 12.5 kV, 22 kHz and 30 kV insulated medium frequency transformer for compact and reliable medium voltage power conversion

    CERN Document Server

    Isler, Stephane; Aguglia, Davide; Bonnin, Xavier Abel

    2017-01-01

    This paper presents the critical design aspects addressed during the development of a 100 kW, 12.5 kV, 22 kHz, and 30 kV insulated medium frequency transformer used in a power converter. The transformers are used in a resonant multilevel converter topology producing HV DC voltage from a three phase 400 V AC industrial grid. The power converter is used to supply radio frequency systems in particle accelerators. Considerations about material selection, dielectric, magnetic and thermal design are discussed and experimental results on the full scale transformer and power converter are presented.

  18. Integrated Differential Three-Level High-Voltage Pulser Output Stage for CMUTs

    DEFF Research Database (Denmark)

    Llimos Muntal, Pere; Larsen, Dennis Øland; Jørgensen, Ivan Harald Holger

    2015-01-01

    A new integrated differential three-level highvoltage pulser output stage to drive capacitive micromachined ultrasonic transducers (CMUTs) is proposed in this paper. A topology comparison between the new differential output stage and the most commonly used single-ended topology is performed...... levels of 60, 80, 100V using 0.039mm2 of chip area. The power consumption is 0.951mW for a 30 pF CMUT load. The design presented is implemented in a 0.35 μm high-voltage process....

  19. Huggable Communication Medium Maintains Level of Trust during Conversation Game.

    Science.gov (United States)

    Takahashi, Hideyuki; Ban, Midori; Osawa, Hirotaka; Nakanishi, Junya; Sumioka, Hidenobu; Ishiguro, Hiroshi

    2017-01-01

    There have been several attempts in recent years to develop a remote communication device using sensory modalities other than speech that would induce a user's positive experience with his/her conversation partner. Specifically, Hugvie is a human-shaped pillow as well as a remote communication device enabling users to combine a hugging experience with telecommunication to improve the quality of remote communication. The present research is based on the hypothesis that using Hugvie maintains users' level of trust toward their conversation partners in situations prone to suspicion. The level of trust felt toward other remote game players was compared between participants using Hugvie and those using a basic communication device while playing a modified version of Werewolf , a conversation-based game, designed to evaluate trust. Although there are always winners and losers in the regular version of Werewolf , the rules were modified to generate a possible scenario in which no enemy was present among the players and all players would win if they trusted each other. We examined the effect of using Hugvie while playing Werewolf on players' level of trust toward each other and our results demonstrated that in those using Hugvie , the level of trust toward other players was maintained.

  20. Huggable Communication Medium Maintains Level of Trust during Conversation Game

    Directory of Open Access Journals (Sweden)

    Hideyuki Takahashi

    2017-10-01

    Full Text Available There have been several attempts in recent years to develop a remote communication device using sensory modalities other than speech that would induce a user’s positive experience with his/her conversation partner. Specifically, Hugvie is a human-shaped pillow as well as a remote communication device enabling users to combine a hugging experience with telecommunication to improve the quality of remote communication. The present research is based on the hypothesis that using Hugvie maintains users’ level of trust toward their conversation partners in situations prone to suspicion. The level of trust felt toward other remote game players was compared between participants using Hugvie and those using a basic communication device while playing a modified version of Werewolf, a conversation-based game, designed to evaluate trust. Although there are always winners and losers in the regular version of Werewolf, the rules were modified to generate a possible scenario in which no enemy was present among the players and all players would win if they trusted each other. We examined the effect of using Hugvie while playing Werewolf on players’ level of trust toward each other and our results demonstrated that in those using Hugvie, the level of trust toward other players was maintained.

  1. The Project Outcome “Assessment of the Impact of Medium Voltage Power Lines on Avifauna in Mangistau Region (Kazakhstan”

    Directory of Open Access Journals (Sweden)

    Mark V. Pestov

    2016-02-01

    Full Text Available The article highlights the project results on the assessment of the impact of middle voltage overhead power lines (PL on avifauna of Mangistau region of the Republic of Kazakhstan. On repeated examination of 440 km of PL there was determined a fact of death of 123 birds belonging to 29 species. In particular, 23 birds died from injuries because of collision with wires, and 100 birds were electrocuted. Among the latter, about 60 % are eagles (Steppe Eagle Aquila nipalensis, Golden Eagle Aquila chrysaetos, Imperial Eagle Aquila heliaca. There is the dependence of a number of electrocuted birds on the engineering design of PL. There was an extrapolation of the bird electrocution survey results on the whole territory of Mangistau region.

  2. Low and medium level radioactive waste repository: risk perception

    International Nuclear Information System (INIS)

    Aquino, Afonso Rodrigues de; Bueno, Lilian de Oliveira; Vieira, Martha Marques Ferreira; Fonseca, Edvaldo Roberto Paiva da; Bellintani, Sandra Aparecida

    2009-01-01

    This paper focuses on the risk perception associated to the installation of low and intermediate level radioactive waste (LLRW and ILRW) disposal facilities. The purpose is to give support for the implementation of a repository in Brazil. Public acceptance results from a long term work and trust is vital for the process as it takes long to be conquered but might be shortly lost. Therefore, it is essential to care about the way each step is conducted. The knowledge about the system and the risks, the comprehension about these risks, the commitment with safety, adequate support systems for the project (legislation, involved institutions) and the excellence as a goal to be reached are extremely important parameters. The involvement of all interested parties in the decision-making process is condition for a successful and publicly acceptable implementation of such project. The steps for public acceptance of a repository are summarized as follow: Risk perception: to verify how the local population understand and feel the installation of a repository in the region. Media observatory: to continuously follow the news reaching the region where the repository will be installed, including different media. Local population social/economical/cultural profile identification: to determine the local population social/economical/cultural profile; to conduct a survey to know their expectations, allowing the proposal of compensation and incentives to fully account for their expectations. Finally, the philosophy governing this Project is: on doubt, the public must be heard and only after this public hearing the policies concerning the project shall be formulated. (author)

  3. Low and medium level radioactive waste repository: risk perception

    Energy Technology Data Exchange (ETDEWEB)

    Aquino, Afonso Rodrigues de; Bueno, Lilian de Oliveira; Vieira, Martha Marques Ferreira; Fonseca, Edvaldo Roberto Paiva da; Bellintani, Sandra Aparecida [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], e-mail: araquino@ipen.br, e-mail: lbueno@ipen.br, e-mail: mmvieira@ipen.br, e-mail: efonseca@ipen.br, e-mail: sbellint@ipen.br

    2009-07-01

    This paper focuses on the risk perception associated to the installation of low and intermediate level radioactive waste (LLRW and ILRW) disposal facilities. The purpose is to give support for the implementation of a repository in Brazil. Public acceptance results from a long term work and trust is vital for the process as it takes long to be conquered but might be shortly lost. Therefore, it is essential to care about the way each step is conducted. The knowledge about the system and the risks, the comprehension about these risks, the commitment with safety, adequate support systems for the project (legislation, involved institutions) and the excellence as a goal to be reached are extremely important parameters. The involvement of all interested parties in the decision-making process is condition for a successful and publicly acceptable implementation of such project. The steps for public acceptance of a repository are summarized as follow: Risk perception: to verify how the local population understand and feel the installation of a repository in the region. Media observatory: to continuously follow the news reaching the region where the repository will be installed, including different media. Local population social/economical/cultural profile identification: to determine the local population social/economical/cultural profile; to conduct a survey to know their expectations, allowing the proposal of compensation and incentives to fully account for their expectations. Finally, the philosophy governing this Project is: on doubt, the public must be heard and only after this public hearing the policies concerning the project shall be formulated. (author)

  4. Low concentration contrast medium for dual-source computed tomography coronary angiography by a combination of iterative reconstruction and low-tube-voltage technique: Feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Minwen, E-mail: zhengmw2007@163.com; Liu, Ying, E-mail: yingyinglyly@126.com; Wei, Mengqi, E-mail: weimengqi2008@163.com; Wu, Yongjie, E-mail: wu18291988526@163.com; Zhao, Hongliang, E-mail: zhaohl1980@163.com; Li, Jian, E-mail: xjyylj@yeah.net

    2014-02-15

    Objectives: To assess the impact of low-concentration contrast medium on vascular enhancement, image quality and radiation dose of coronary CT angiography (cCTA) by using a combination of iterative reconstruction (IR) and low-tube-voltage technique. Materials and methods: One hundred patients were prospectively randomized to two types of contrast medium and underwent prospective electrocardiogram-triggering cCTA (Definition Flash, Siemens Healthcare; collimation: 128 mm × 0.6 mm; tube current: 300 mA s). Fifty patients received Iopromide 370 were scanned using the conventional tube setting (100 kVp or 120 kVp if BMI ≥ 25 kg/m{sup 2}) and reconstructed with filtered back projection (FBP). Fifty patients received Iodixanol 270 were scanned using the low-tube-voltage (80 kVp or 100 kVp if BMI ≥ 25 kg/m{sup 2}) technique and reconstructed with IR. CT attenuation was measured in coronary artery and other anatomical regions. Noise, image quality and radiation dose were compared. Results: Compared with two Iopromide 370 subgroups, Iomeprol 270 subgroups showed no significant difference in CT attenuation (576.63 ± 95.50 vs. 569.51 ± 118.93 for BMI < 25 kg/m{sup 2}, p = 0.647 and 394.19 ± 68.09 vs. 383.72 ± 63.11 for BMI ≥ 25 kg/m{sup 2}, p = 0.212), noise (in various anatomical regions of interest) and image quality (3.5 vs. 4.0, p = 0.13), but significantly (0.41 ± 0.17 vs. 0.94 ± 0.45 for BMI < 25 kg/m{sup 2}, p < 0.001 and 1.14 ± 0.24 vs. 2.37 ± 0.69 for BMI ≥ 25 kg/m{sup 2}, p < 0.001) lower radiation dose, which reflects dose saving of 56.4% and 51.9%, respectively. Conclusions: Combined IR with low-tube-voltage technique, a low-concentration contrast medium of 270 mg I/ml can still maintain the contrast enhancement without impairing image quality, as well as significantly lower the radiation dose.

  5. Analysis of Two New Voltage Level Converters With Various Load Conditions

    Directory of Open Access Journals (Sweden)

    Prof.(Dr.AVIRENI SRINIVASULU

    2013-10-01

    Full Text Available The use of level converter in dual supply voltage circuits is one of the most effective ways to reduce power consumption. To prevent static current, level converter is introduced as an interface at each low-to-high boundary. The design of an efficient level converter with least power consumption and overheads delay is one of the major design constraints. In this paper, two new level converter circuits with low power consumption are proposed for less propagation delay and load adaptability. The proposed level converter circuits are examined using cadence and the design parameters of a 180 nm CMOS process. The simulation results exhibit that proposed level converter can reduce propagation delay and increase speed over the existing circuits available. These level converters are simulated for different loads and operating conditions. The proposed level converter can operate at different values of VDDL as +1 V, +1.8 V, +2 V and VDDH of +3.3 V. The topology reports low sensitivity and has features suitable for VLSI implementation. The proposed circuits are suited for low power design without degrading performance.  

  6. Mercure IV code application to the external dose computation from low and medium level wastes

    International Nuclear Information System (INIS)

    Tomassini, T.

    1985-01-01

    In the present work the external dose from low and medium level wastes is calculated using MERCURE IV code. The code utilizes MONTECARLO method for integrating multigroup line of sight attenuation Kernels

  7. Correlation between the thermal performance and the microstructure of the material used in medium and high voltage transformer terminals

    Science.gov (United States)

    Salas, Y. J.; Vera-Monroy, S. P.; Mejia-Camacho, A.; Rivera, W.

    2017-12-01

    In Colombia, energy companies neglect the distribution that represents the main and most valuable process, presenting shortcomings in prevention and forecasting programs, using contractors who perform corrective maintenance of the components without guaranteeing the quality and performance of the materials. Within the process, the terminals determine the effective connection between the voltage line and the transformer, which have faults that are evidenced by the thermal deterioration of the material. In this work, a diagnosis of the thermal performance of these components was carried out and it was correlated with the microstructure, observing variations of the working temperature, with a thermography camera, for three types of terminals, which were classified by X-ray fluorescence in brass Z20, Z40 and Z60, and for two types of connection, copper and aluminium. The microstructure results showed that copper is the conductor that degrades the terminals faster, evidencing cracking of the material; on the other hand, the Z40 brass was the most stable with the lowest temperature variation regardless of the conductor diameter; however, in all cases the behaviour of higher temperature to lower calibre is satisfied.

  8. Estimation of Sparkover Rate of Medium-Voltage Line due to Direct Lightning Hit Taking Account of Statistics on Observed Return-Stroke Current

    Science.gov (United States)

    Hongo, Yasuji; Michishita, Koji

    The overvoltage associated with direct lightning hits has been the important factor for the insulation design of a distribution line. In this paper, the sparkover rate of a medium-voltage line associated with direct lightning hits is investigated based on numerical calculations obtained by using EMTP and statistical analysis by taking account of the correlation between the peak value and the front duration of return-stroke current waveform. When the line is equipped with surge arresters at the interval of 100m in addition to the overhead ground wire, the sparkover rate associated with subsequent strokes is higher than that associated with first strokes. This demonstrates the importance of the study of current parameters for subsequent strokes.

  9. Simulation of rectifier voltage malfunction on OWECS, four-level converter, HVDC light link: Smart grid context tool

    International Nuclear Information System (INIS)

    Seixas, M.; Melício, R.; Mendes, V.M.F.

    2015-01-01

    Highlights: • Floating offshore wind turbine in deep water. • DC link and voltage malfunction. • Converter topology considered is four-level. • Controllers are based on fractional-order. • Smart grid context. - Abstract: This paper presents a model for the simulation of an offshore wind system having a rectifier input voltage malfunction at one phase. The offshore wind system model comprises a variable-speed wind turbine supported on a floating platform, equipped with a permanent magnet synchronous generator using full-power four-level neutral point clamped converter. The link from the offshore floating platform to the onshore electrical grid is done through a light high voltage direct current submarine cable. The drive train is modeled by a three-mass model. Considerations about the smart grid context are offered for the use of the model in such a context. The rectifier voltage malfunction domino effect is presented as a case study to show capabilities of the model

  10. CESARR V.2 manual: Computer code for the evaluation of surface storage of low and medium level radioactive waste

    International Nuclear Information System (INIS)

    Moya Rivera, J.A.; Bolado Lavin, R.

    1997-01-01

    CESARR (Code for the safety evaluation of low and medium level radioactive waste storage). This code was developed for the safety probabilistic evaluations in the facilities of low-and medium level radioactive waste storage

  11. Design of Neutral-Point Voltage Controller of a Three-level NPC Inverter with Small DC-Link Capacitors

    DEFF Research Database (Denmark)

    Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Busquets-Monge, S.

    2013-01-01

    . This continuous model shows that the neutral-point current is proportional to the power drawn from the inverter, and it enables the use of well established classical control theory for the neutral-point voltage controller design. A simple PI (proportional integral) controller is designed for the neutral......-point voltage control on the basis of the continuous model. The design method for optimum performance is discussed. The implementation of the proposed modulation strategy and the controller is very simple. The controller is implemented in a 7.5 kW induction machine based drive with only 14 ìF dc-link capacitors......A Neutral-Point-Clamped (NPC) three-level inverter with small dc-link capacitors is presented in this paper. The inverter requires zero average neutral-point current for stable neutral-point voltage. The small dc-link capacitors may not maintain capacitor voltage balance, even with zero neutral...

  12. Cloud Computing: The Level of Awareness Amongst Small & Medium-sized Enterprises (SMEs) in Developing Economies

    DEFF Research Database (Denmark)

    Yeboah-Boateng, Ezer Osei; Essandoh, Kofi Asare

    2013-01-01

    indicated that a slight majority of the respondents were familiar with cloud computing on the individual level but the level of awareness amongst the larger SME industry was low to medium. The finding therefore recommends education and sensitization on cloud computing in order to increase awareness...

  13. High-voltage measurements on the 5 ppm relative uncertainty level with collinear laser spectroscopy

    Science.gov (United States)

    Krämer, J.; König, K.; Geppert, Ch; Imgram, P.; Maaß, B.; Meisner, J.; Otten, E. W.; Passon, S.; Ratajczyk, T.; Ullmann, J.; Nörtershäuser, W.

    2018-04-01

    We present the results of high-voltage collinear laser spectroscopy measurements on the 5 ppm relative uncertainty level using a pump and probe scheme at the 4s ^2S1/2 → 4p ^2P3/2 transition of {\\hspace{0pt}}40Ca+ involving the 3d ^2D5/2 metastable state. With two-stage laser interaction and a reference measurement we can eliminate systematic effects such as differences in the contact potentials due to different electrode materials and thermoelectric voltages, and the unknown starting potential of the ions in the ion source. Voltage measurements were performed between  -5 kV and  -19 kV and parallel measurements with stable high-voltage dividers calibrated to 5 ppm relative uncertainty were used as a reference. Our measurements are compatible with the uncertainty limits of the high-voltage dividers and demonstrate an unprecedented (factor of 20) increase in the precision of direct laser-based high-voltage measurements.

  14. An Enhanced Three-Level Voltage Switching State Scheme for Direct Torque Controlled Open End Winding Induction Motor

    Science.gov (United States)

    Kunisetti, V. Praveen Kumar; Thippiripati, Vinay Kumar

    2018-01-01

    Open End Winding Induction Motors (OEWIM) are popular for electric vehicles, ship propulsion applications due to less DC link voltage. Electric vehicles, ship propulsions require ripple free torque. In this article, an enhanced three-level voltage switching state scheme for direct torque controlled OEWIM drive is implemented to reduce torque and flux ripples. The limitations of conventional Direct Torque Control (DTC) are: possible problems during low speeds and starting, it operates with variable switching frequency due to hysteresis controllers and produces higher torque and flux ripple. The proposed DTC scheme can abate the problems of conventional DTC with an enhanced voltage switching state scheme. The three-level inversion was obtained by operating inverters with equal DC-link voltages and it produces 18 voltage space vectors. These 18 vectors are divided into low and high frequencies of operation based on rotor speed. The hardware results prove the validity of proposed DTC scheme during steady-state and transients. From simulation and experimental results, proposed DTC scheme gives less torque and flux ripples on comparison to two-level DTC. The proposed DTC is implemented using dSPACE DS-1104 control board interface with MATLAB/SIMULINK-RTI model.

  15. Volume reduction of low- and medium-level waste by incineration/calcination

    International Nuclear Information System (INIS)

    Buzonniere, A. de; Gauthey, J.C.

    1993-01-01

    Nuclear installations generate large quantities of low- and medium-level radwaste. This waste comes from various installations in the fuel cycle, reactor operation, research institute, hospitals, nuclear plate dismantling, etc.. TECHNICATOME did the project development work for the incineration plant of PIERRELATE (France) on behalf of COGEMA (Compagnie Generale des d'Etudes Technique). This plant has been in active service since November 1987. In addition, TECHNICATOME was in charge of the incinerator by a turnkey contract. This incinerator was commissioned in 1992. For a number of years, TECHNICATOME has been examining, developing and producing incineration and drying/calcination installations. They are used for precessing low- and medium-level radwaste

  16. DC Bus Control of Back-to-Back Connected Two-Level PWM Rectifier-Five-Level NPC Voltage Source Inverter to Torque Ripple Reduction in Induction Motor

    Directory of Open Access Journals (Sweden)

    Abdelkrim Thameur

    2015-01-01

    Full Text Available This paper proposes a regulation method of back-to-back connected two-level PWM rectifier-five-level Voltage Source Inverter (VSI in order to reduce the torque ripple in induction motor. First part is dedicated to the presentation of the feedback control of two-level PWM rectifier. In the second part, five-level Neutral Point Clamped (NPC voltage source inverter balancing DC bus algorithm is presented. A theoretical analysis with a complete simulation of the system is presented to prove the excellent performance of the proposed technique.

  17. Recycling ``in situ`` of dielectric oil of electric transformer of medium and high voltage; Reciclaje ``in situ`` y ``en carga`` del aceite dielectrico de los transformadores electricos de media y alta tension

    Energy Technology Data Exchange (ETDEWEB)

    Solis, A.

    1997-06-01

    The author describes the process followed by the company to control the quality of every type of oil from electric transformer of medium and high voltage polluted because of its use. The pollutants contained in the dielectric liquid are eliminated or minimize through the following treatments: conditioning-reconditioning-regeneration. (Author) 6 refs.

  18. Design and Control of a Dynamic Voltage Restorer

    DEFF Research Database (Denmark)

    Nielsen, John Godsk

    of the described events can be a potential problem for sensitiv loads. During the thesis knowledge is gathered about power quality and power electronics for voltage quality improvements. In addition knowledge about the design and control of a DVR either connected at the low voltage or the medium voltage level......This thesis is the main results from a Ph.D. project under the research programme "Local Compensation" at Aalborg University. The main topics in the thesis are the design and control of a Dynamic Voltage Restorer (DVR). The DVR is a series connected device, which primarily can protect sensitive...... electric consumers against voltage dips and surges in the medium and low voltage distribution grid. The thesis first gives an introduction to relevant power quality issues for a DVR and power electronic controllers for voltage dip mitigation. Thereafter the operation and the elements in a DVR are described...

  19. Entanglement of a nonlinear two two-level atoms interacting with deformed fields in Kerr medium

    Science.gov (United States)

    Abdel-Khalek, S.; El-Saman, Y. S.; Abdel-Aty, M.

    2018-01-01

    In this paper we investigate the entanglement dynamics between two two-level atoms interacting with two coherent fields in two spatially separated cavities which are filled with a Kerr-like medium. We examine the effect of nonlinear medium on the dynamical properties of entanglement and atomic occupation probabilities in the case of even and odd deformed coherent states. The results show that the deformed fields play important roles in the evolution of entanglement. Also, the results demonstrate that entanglement sudden death, sudden birth and long-distance can be controlled by the deformation and nonlinear parameters.

  20. Submerged Medium Voltage Cable Systems at Nuclear Power Plants. A Review of Research Efforts Relevant to Aging Mechanisms and Condition Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Jason [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bernstein, Robert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); White, II, Gregory Von [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Glover, Steven F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Neely, Jason C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pena, Gary [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Williamson, Kenneth Martin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Zutavern, Fred J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gelbard, Fred [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-03-01

    and industrial literature was performed to identify : 1) findings regarding the degradation mechanisms of submerged cabling and 2) condition monitoring methods that may prove useful in predict ing the remaining lifetime of submerged medium voltage p ower cables . The re search was conducted by a multi - disciplinary team , and s ources includ ed official NRC reports, n ational l aboratory reports , IEEE standards, conference and journal proceedings , magazine articles , PhD dissertations , and discussions with experts . The purpose of this work was to establish the current state - of - the - art in material degradation modeling and cable condition monitoring techniques and to identify research gaps . Subsequently, future areas of focus are recommended to address these research gaps and thus strengthen the efficacy of the NRC's developing cable condition monitoring program . Results of this literature review and details of the test ing recommendations are presented in this report . FOREWORD To ensure the safe, re liable, and cost - effective long - term operation of nuclear power plants, many systems, structures, and components must be continuously evaluated. The Nuclear Regulatory Commission (NRC) has identified that cables in submerged environments are of concern, particularly as plants are seeking license renewal. To date, there is a lack of consensus on aging and degradation mechanisms even though the area of submerged cables has been extensively studied. Consequently, the ability to make lifetime predictions for submerged cable does not yet exist. The NRC has engaged Sandia National Laboratories (SNL) to lead a coordinated effort to help elucidate the aging and degradation of cables in submerged environments by collaborating with cable manufacturers, utilities, universities, and other government agencies. A team of SNL experts was assembled from the laboratories including electrical condition monitoring, mat erial science, polymer degradation, plasma physics

  1. Loading Analysis of Modular Multi-level Converter for Offshore High-voltage DC Application under Various Grid Faults

    DEFF Research Database (Denmark)

    Liu, Hui; Ma, Ke; Loh, Poh Chiang

    2016-01-01

    challenges but may also result in overstressed components for the modular multi-level converter. However, the thermal loading of the modular multi-level converter under various grid faults has not yet been clarified. In this article, the power loss and thermal performance of the modular multi-level converter...... during grid voltage dips are studied. The impacts of two typical grid faults to the modular multi-level converter in terms of operating and loading conditions are analytically researched and simulated. It has been found that the operating and loading conditions of the modular multi-level converter under...

  2. Identification of the primary compensating defect level responsible for determining blocking voltage of vertical GaN power diodes

    Science.gov (United States)

    King, M. P.; Kaplar, R. J.; Dickerson, J. R.; Lee, S. R.; Allerman, A. A.; Crawford, M. H.; Fischer, A. J.; Marinella, M. J.; Flicker, J. D.; Fleming, R. M.; Kizilyalli, I. C.; Aktas, O.; Armstrong, A. M.

    2016-10-01

    Electrical performance and characterization of deep levels in vertical GaN P-i-N diodes grown on low threading dislocation density (˜104 - 106 cm-2) bulk GaN substrates are investigated. The lightly doped n drift region of these devices is observed to be highly compensated by several prominent deep levels detected using deep level optical spectroscopy at Ec-2.13, 2.92, and 3.2 eV. A combination of steady-state photocapacitance and lighted capacitance-voltage profiling indicates the concentrations of these deep levels to be Nt = 3 × 1012, 2 × 1015, and 5 × 1014 cm-3, respectively. The Ec-2.92 eV level is observed to be the primary compensating defect in as-grown n-type metal-organic chemical vapor deposition GaN, indicating this level acts as a limiting factor for achieving controllably low doping. The device blocking voltage should increase if compensating defects reduce the free carrier concentration of the n drift region. Understanding the incorporation of as-grown and native defects in thick n-GaN is essential for enabling large VBD in the next-generation wide-bandgap power semiconductor devices. Thus, controlling the as-grown defects induced by epitaxial growth conditions is critical to achieve blocking voltage capability above 5 kV.

  3. New MMC capacitor voltage balancing using sorting-less strategy in nearest level control

    DEFF Research Database (Denmark)

    Ricco, Mattia; Máthé, Lászlo; Teodorescu, Remus

    2016-01-01

    This paper proposes a new strategy for balancing the Capacitor Voltages (CVs) for Modular Multilevel Converters (MMCs). The balancing is one of the main challenges in MMC applications and it is usually solved by adopting a global arm control approach. For performing such an approach, a sorted list...

  4. On correctness of the two-level model for description of active medium in quantum plasmonics

    Science.gov (United States)

    Chubchev, E. D.; Andrianov, E. S.; Pukhov, A. A.; Vinogradov, A. P.; Lisyansky, A. A.

    2017-09-01

    In order to simplify the theoretical description of spasers, a gain medium is commonly represented by a two-level system (TLS). A realistic model, however, should have four levels. By using the Lindblad equations we develop a description of such a system and show that depending on ratios of the Rabi frequency and the rate of relaxation of the polarization, a four-level system (FLS) may be reduced to one of two effective TLSs that reproduce the key properties of a FLS.

  5. Thermal characteristics of a medium-level concentration photovoltaic unit with evaporation cooling

    Science.gov (United States)

    Kokotov, Yuri V.; Reyz, Michael A.; Fisher, Yossi

    2009-08-01

    The results of thermal analysis and experiments are presented for a 1-kW brand new medium-level (8X) concentration photovoltaic (CPV) unit that is cooled by evaporation and built as an elongated floating solar unit. The unit keeps the silicon PV elements at low and stable temperature around the clock, significantly outperforms competitors' systems in terms of the power output and the life span of identical PV elements. It is demonstrated theoretically and experimentally that the PV element temperature level exceeds the temperature level of water in the water basin (used as a heat sink) by just a few degrees.

  6. The incorporation of low and medium level radioactive wastes (solids and liquids) in cement

    International Nuclear Information System (INIS)

    Palmer, J.D.; Smith, D.L.G.

    1986-01-01

    The use of cement has been investigated for the immobilization of liquid and solid low and medium level radioactive waste. 220 litre mixing trials have demonstrated that the high temperatures generated during the setting of ordinary Portland cement/simulant waste mixes can be significantly reduced by the use of a blend of ground granulated blast furnace slag and ordinary Portland cement. Laboratory and 220 litre trials using simulant wastes showed that the blended cement gave an improvement in properties of the cemented waste product, e.g. stability and reduction in leach rates compared with ordinary Portland cement formulations. A range of 220 litre scale mixing systems for the incorporation of liquid and solid wastes in cement was investigated. The work has confirmed that cement-based processes can be used for the immobilization of most types of low and medium level waste

  7. The Cabril: The Spanish Storage Site for Low and medium Level Radioactive Wastes

    International Nuclear Information System (INIS)

    Zuloaga, P.

    1993-01-01

    The new installations at El Cabril are one of the most modern storage sites for low and medium level radioactive wastes worldwide. The site was conceived in such a way that it is possible its reutilization without any radiological restriction after its current surveillance period of 300 years. Additionally, the installations have enough of a capacity to store all the medium and low level wastes to be produced in Spain during the next 30 years plus all the already gathered ones at the three old installations. In order to achieve all the objectives a storage system, a control network and installations for sewage water treatment are available. An incinerator to burn biological and organic wastes from hospitals and a laboratory of wastes characterization complete the variety of installations

  8. The incorporation of low and medium level radioactive wastes (solids and liquids) in cement

    International Nuclear Information System (INIS)

    Palmer, J.D.; Smith, D.L.

    1985-07-01

    Experimentation has shown that high temperatures generated during the setting of ordinary Portland cement/simulant waste mixes can be significantly reduced by the use of a blend of ground granulated blast furnace slag and ordinary Portland cement. Trials on simulated waste showed that blended cement gave improved stability and a reduction in leach rates, and confirmed that the cement-based process can be used for the immobilisation of most types of low and medium level waste. (U.K.)

  9. Plasma arc and cold crucible furnace vitrification for medium level waste: a review

    International Nuclear Information System (INIS)

    Poitou, S.; Fiquet, O.; Bourdeloie, C.; Gramondi, P.; Rebollo, F.; Girold, C.; Charvillat, J.P.; Boen, R.; Jouan, A.; Ladirat, C.; Nabot, J.P.; Ochem, D.; Baronnet, J.M.

    2001-01-01

    Initially developed for high-level waste reprocessing, several vitrification processes have been under study since the 80's at the French Atomic Energy Commission (CEA) for other waste categories. According to the French law concerning waste management research passed on December 30, 1991, vitrification may be applied to mixed medium-level waste. A review of processes developed at CEA is presented: cold crucible furnace heated by induced current, refractory furnace heated by nitrogen transferred arc plasma torch, and coupling of cold crucible furnace with oxygen transferred plasma arc twin torch. Furthermore, gas post-combustion has been studied with an oxygen non-transferred plasma torch. (authors)

  10. SCREENING OF MEDIUM COMPOUNDS USING A TWO-LEVEL FACTORIAL DESIGN FOR SACCHAROMYCES BOULARDII

    Directory of Open Access Journals (Sweden)

    GUOWEI SHU

    2016-04-01

    Full Text Available Even if the probiotic effect of Saccharomyces boulardii is has been reported, this yeast is rarely used in medium composition. Based on single factor experiment, two-level factorial design was employed to evaluate the effect of carbon sources (sucrose, glucose, nitrogen sources (soy peptone, beef extract, yeast extract, calf serum, malt extract and salts (K2HPO4, KH2PO4, MgSO4, Na2HPO4, NaH2PO4, CaCl2, sodium citrate, sodium glutamate on the growth of S. boulardii. At the same time, the optical density (OD in the medium was measured at 560 nm after 36 h of incubation. The result of two-level factorial design experiment showed that calf serum (p = 0.0214 and sodium citrate (p = 0.0045 are the significant growth factors of S. boulardii, sucrose (p = 0.0861 and malt extract (p = 0.0763 are important factors. In addition, sucrose and sodium citrate showed positive effect on the growth of S. boulardii. However, calf serum and malt extract showed negative effect on the growth. And we determined that the optimum medium composition for S. boulardii was as follow: 37.5 g·L-1 sucrose, 6 g·L-1 calf serum, 6 g·L-1 malt extract, 5 g·L-1 sodium citrate.

  11. Diagnostic accuracy of low and high tube voltage coronary CT angiography using an X-ray tube potential-tailored contrast medium injection protocol.

    Science.gov (United States)

    Albrecht, Moritz H; Nance, John W; Schoepf, U Joseph; Jacobs, Brian E; Bayer, Richard R; Litwin, Sheldon E; Reynolds, Michael A; Otani, Katharina; Mangold, Stefanie; Varga-Szemes, Akos; De Santis, Domenico; Eid, Marwen; Apfaltrer, Georg; Tesche, Christian; Goeller, Markus; Vogl, Thomas J; De Cecco, Carlo N

    2018-05-01

    To compare the diagnostic accuracy between low-kilovolt peak (kVp) (≤ 100) and high-kVp (> 100) third-generation dual-source coronary CT angiography (CCTA) using a kVp-tailored contrast media injection protocol. One hundred twenty patients (mean age = 62.6 years, BMI = 29.0 kg/m 2 ) who underwent catheter angiography and CCTA with automated kVp selection were separated into two cohorts (each n = 60, mean kVp = 84 and 117). Contrast media dose was tailored to the kVp level: 70 = 40 ml, 80 = 50 ml, 90 = 60 ml, 100 = 70 ml, 110 = 80 ml, and 120 = 90 ml. Contrast-to-noise ratio (CNR) was measured. Two observers evaluated image quality and the presence of significant coronary stenosis (> 50% luminal narrowing). Diagnostic accuracy (sensitivity/specificity) with ≤ 100 vs. > 100 kVp CCTA was comparable: per patient = 93.9/92.6% vs. 90.9/92.6%, per vessel = 91.5/97.8% vs. 94.0/96.8%, and per segment = 90.0/96.7% vs. 90.7/95.2% (all P > 0.64). CNR was similar (P > 0.18) in the low-kVp vs. high-kVp group (12.0 vs. 11.1), as ws subjective image quality (P = 0.38). Contrast media requirements were reduced by 38.1% in the low- vs. high-kVp cohort (53.6 vs. 86.6 ml, P tube voltage selection with a tailored contrast media injection protocol allows CCTA to be performed at ≤ 100 kVp with substantial dose reductions and equivalent diagnostic accuracy for coronary stenosis detection compared to acquisitions at > 100 kVp. • Low-kVp coronary CT angiography (CCTA) enables reduced contrast and radiation dose. • Diagnostic accuracy is comparable between ≤ 100 and > 100 kVp CCTA. • Image quality is similar for low- and high-kVp CCTA. • Low-kVp image acquisition is facilitated by automated tube voltage selection. • Tailoring contrast injection protocols to the automatically selected kVp-level is feasible.

  12. Comparative Study of Modulation Techniques for Two-Level Voltage Source Inverters

    Directory of Open Access Journals (Sweden)

    Barry W. Williams

    2016-06-01

    Full Text Available A detailed comparative study of modulation techniques for single and three phase dc-ac inverters is presented.  Sinusoidal Pulse Width Modulation, Triplen Sinusoidal Pulse Width Modulation, Space Vector Modulation, Selective Harmonic Elimination and Wavelet Modulation are assessed and compared in terms of maximum fundamental output, harmonic performance, switching losses and operational mode.  The presented modulation techniques are applied to single and three phase voltage source inverters and are simulated using SIMULINK.  The simulation results clarify the inverter performance achieved using the different modulations techniques.

  13. Environmental variables evaluation on concrete structures corrosion for medium level activities repositories

    International Nuclear Information System (INIS)

    Requena, Carlos; Alvarez, Marta G.; Duffo, Gustavo S.

    2000-01-01

    The main purpose of this work was to evaluate the long term durability of reinforced concrete structures as medium-level waste container material. Electrochemical techniques have been used to evaluate the corrosion behaviour of steel rebars in several solutions simulating the liquid present in the pores of both alkaline and carbonated concrete in the presence of sulphate ions. Results shown that a decrease in p H has an adverse effect on the critical sulphate concentration. The inhibition effect of high carbonate/bicarbonate concentration is also shown. (author)

  14. Propagation of frequency-chirped laser pulses in a medium of atoms with a Λ-level scheme

    International Nuclear Information System (INIS)

    Demeter, G.; Dzsotjan, D.; Djotyan, G. P.

    2007-01-01

    We study the propagation of frequency-chirped laser pulses in optically thick media. We consider a medium of atoms with a Λ level-scheme (Lambda atoms) and also, for comparison, a medium of two-level atoms. Frequency-chirped laser pulses that induce adiabatic population transfer between the atomic levels are considered. They induce transitions between the two lower (metastable) levels of the Λ-atoms and between the ground and excited states of the two-level atoms. We show that associated with this adiabatic population transfer in Λ-atoms, there is a regime of enhanced transparency of the medium--the pulses are distorted much less than in the medium of two-level atoms and retain their ability to transfer the atomic population much longer during propagation

  15. Losses Evaluation for a Two-Level Three-Phase Stand-Alone Voltage Source Converter Using Model Predictive Control

    DEFF Research Database (Denmark)

    Al hasheem, Mohamed; Dragicevic, Tomislav; Rivera, Marco

    2017-01-01

    conventional and improved controller is conducted in terms of losses. The switching and conduction losses for the VSC are calculated using MATLAB/SIMULINK and PLECS software. A power level up to 1 kW is considered for the conventional and the improved schemes. All simulation and experimental results......This paper discusses a Model Predictive Control (MPC) scheme for a Voltage Source Converter (VSC) where the aim is to minimize losses and Total Harmonics distortion (THD) compared to the conventional MPC scheme. Different Cost Functions (CFs) are applied to the stand-alone VSC. A comparison between...

  16. Benchmarking of Voltage Sag Generators

    DEFF Research Database (Denmark)

    Yang, Yongheng; Blaabjerg, Frede; Zou, Zhixiang

    2012-01-01

    The increased penetration of renewable energy systems, like photovoltaic and wind power systems, rises the concern about the power quality and stability of the utility grid. Some regulations for Low Voltage Ride-Through (LVRT) for medium voltage or high voltage applications, are coming into force...

  17. Compatibility of cement with low and medium level wastes generated at nuclear power plants

    International Nuclear Information System (INIS)

    De Angelis, G.

    1987-01-01

    The incorporation of low- and medium level wastes in cement can give rise to serious problems due to the interaction between radwastes and cement components. Some troubles can occur during the first stages of the cementation process while deleterious phenomena come into evidence in the medium and long term. With the aim to improve the quality of the final waste forms a pretreatment of the waste streams is often necessary, as well as the addition of special agents to the cement matrix. The prediction of the long-term behaviour of the final products is of main importance in this research field. To this purpose some accelerated tests have been proposed, but much effort should be further devoted to the comprehension of the waste/matrix interaction. In this paper the principal waste streams are reviewed together with the possible remedies which seem to be more suitable for their cementation. Thus the qpportunity of separatly handling and solidifying different types of waste is once more supported

  18. Changes in plant medium composition after a spaceflight experiment: Potassium levels are of special interest

    Science.gov (United States)

    Levine, Howard G.; Krikorian, A. D.

    2008-09-01

    We present results on the analysis of 100 mL medium samples extracted from sterilized foam (Smithers-Oasis, Kent OH) used to support the growth of a representative dicotyledon ( Haplopappus gracilis) and a representative monocotyledon ( Hemerocallis cv Autumn Blaze) in NASA's Plant Growth Unit (PGU) during a 5-day Space Shuttle flight and ground experiments. At recovery, the media remaining within replicate ( n = 5) foam blocks (for both the spaceflight and ground experiments) were extracted under vacuum, filtered and subjected to elemental analyses. A unique aspect of this experiment was that all plants were either aseptically-generated tissue culture propagated plantlets or aseptic seedling clones. The design of the PGU facilitated the maintenance of asepsis throughout the mission (confirmed by post-flight microbial sampling) and thus any possible impact of microorganisms on medium composition was eliminated. Concentration levels of some elements remained the same, while some decreased and others increased. There was a significant two-fold difference between the final concentrations of potassium when the Earth-based and microgravity experiments were contrasted.

  19. Long-term corrosion behaviour of low-/medium-level waste packages

    International Nuclear Information System (INIS)

    Jendras, M.; Bach, F.W.; Behrens, S.; Birr, Ch.; Hassel, Th.

    2009-01-01

    Full text of publication follows: Storage of low- and medium-level radioactive waste requires safe packages. This means that all materials used for the manufacturing of such packages have to show a sufficient resistance especially against corrosive attacks. Since these packages are generally made from carbon steel an additional coating for corrosion protection - mainly solvent-based polymers - is necessary. However, it is not enough to consider the selection and combination of the materials. Regarding the construction and manufacturing of corrosion-resistant drums for low- and medium-level radioactive waste there also has to be paid closer attention to the joining technologies such as welding. For lifetime prediction of low-/medium-level waste packages reliable experimental data concerning the long-term corrosion behaviour of each material as well as of the components is needed. Therefore sheet metals from carbon steel were galvanized or coated with different solvent-based and water-based corrosion protection materials (epoxy as well as silicone resins). After damaging the anti-corrosion coating of some of these sheets with predefined scratches sets of these samples were stored at higher temperatures in climatic chamber, in simulated waste or aged according to standard DIN EN ISO 9227. All corrosion damages were analyzed by means of metallography (light microscopy as well as scanning electron microscopy of micro-sections). The quantitative influence of the corrosive attacks on the mechanical properties of the materials was examined by mechanical testing according to DIN EN 10002. Besides reduction of tensile strength drastic reduction of percentage of elongation after fracture (from 30 % to 10 %) was found. Further experiments were carried out using components or scaled-down drums joined by means of innovative welding techniques such as Cold Arc or Force Arc. The relevant welding parameters (e.g. welding current, proper volume of shielding gas or wire feed) were

  20. CompactPCI/Linux platform for medium level control system on FTU

    International Nuclear Information System (INIS)

    Wang, L.; Centioli, C.; Iannone, F.; Panella, M.; Mazza, G.; Vitale, V.

    2004-01-01

    In large fusion experiments, such as tokamak devices, there are common trends for slow control systems. Because of complexity of the plants, several tokamaks adopt the so-called 'standard model' (SM) based on a three levels hierarchical control: (i) high level control (HLC) - the supervisor; (ii) medium level control (MLC) - I/O field equipments interface and concentration units and (iii) low level control (LLC) - the programmable logic controllers (PLC). FTU control system was designed with SM concepts and, in its 15 years life cycle, it underwent several developments. The latest evolution was mandatory, due to the obsolescence of the MLC CPUs, based on VME/Motorola 68030 with OS9 operating system. Therefore, we had to look for cost-effective solutions and we chose a CompactPCI-Intel x86 platform with Linux operating system. A software porting has been done taking into account the differences between OS9 and Linux operating system in terms of inter/network processes communications and I/O multi-ports serial driver. This paper describes the hardware/software architecture of the new MLC system emphasising the reliability and the low costs of the open source solutions. Moreover, the huge amount of software packages available in open source environment will assure a less painful maintenance, and will open the way to further improvements of the system itself

  1. Procedures for the site location of an storage centre of medium and low level radioactive wastes

    International Nuclear Information System (INIS)

    Pena G, P.; Garcia B, M.

    2001-01-01

    In order to establish the procedures for the location of a new and definitive storage center for medium and low level radioactive wastes which will be the place where confining, controlling and keeping those waste products of radioactive materials which were used in the hospitable centers, clinics and institutions (research and techniques development) as well as those obtained from industry. The site studies for nuclear facilities, require the participation of a several professionals with different specialities to be able to make use of competence in different disciplines. The result is the exclusion of unacceptable zones followed them by a pre-selection, a selection and a systematic comparison of those sites which are in the remaining zones considered as acceptable. (Author)

  2. Spatial solitons in a three-level atomic medium supported by a Laguerre-Gaussian control beam

    International Nuclear Information System (INIS)

    Hang Chao; Konotop, V. V.

    2011-01-01

    We investigate the existence and stability of various types of spatial solitons in a three-level atomic medium with Laguerre-Gaussian control beam. Radial and azimuthal modulations of the medium properties, introduced by the control beam, provide possibilities for existence of diverse soliton patterns and dynamics. Beam diffraction provides additional soliton controllability. All types of solitons can be generated at very low input energy at a few-photon level.

  3. Energy-level alignment and open-circuit voltage at graphene/polymer interfaces: theory and experiment

    Science.gov (United States)

    Noori, Keian; Konios, Dimitrios; Stylianakis, Minas M.; Kymakis, Emmanuel; Giustino, Feliciano

    2016-03-01

    Functionalized graphene promises to become a key component of novel solar cell architectures, owing to its versatile ability to act either as transparent conductor, electron acceptor, or buffer layer. In spite of this promise, the solar energy conversion efficiency of graphene-based devices falls short of the performance of competing solution-processable photovoltaic technologies. Here we address the question of the maximum achievable open-circuit voltage of all-organic graphene: polymer solar cells using a combined theoretical/experimental approach, going from the atomic scale level to the device level. Our calculations on very large atomistic models of the graphene/polymer interface indicate that the ideal open-circuit voltage approaches one volt, and that epoxide functional groups can have a dramatic effect on the photovoltage. Our predictions are confirmed by direct measurements on complete devices where we control the concentration of functional groups via chemical reduction. Our findings indicate that the selective removal of epoxide groups and the use of ultradisperse polymers are key to achieving graphene solar cells with improved energy conversion efficiency.

  4. Fundamental studies on the switching in liquid nitrogen environment using vacuum switches for application in future high-temperature superconducting medium-voltage power grids

    International Nuclear Information System (INIS)

    Golde, Karsten

    2016-01-01

    By means of superconducting equipment it is possible to reduce the transmission losses in distribution networks while increasing the transmission capacity. As a result even saving a superimposed voltage level would be possible, which can put higher investment costs compared to conventional equipment into perspective. For operation of superconducting systems it is necessary to integrate all equipment in the cooling circuit. This also includes switchgears. Due to cooling with liquid nitrogen, however, only vacuum switching technology comes into question. Thus, the suitability of vacuum switches is investigated in this work. For this purpose the mechanics of the interrupters is considered first. Material investigations and switching experiments at ambient temperature and in liquid nitrogen supply information on potential issues. For this purpose, a special pneumatic construction is designed, which allows tens of thousands of switching cycles. Furthermore, the electrical resistance of the interrupters is considered. Since the contact system consists almost exclusively of copper, a remaining residual resistance and appropriate thermal losses must be considered. Since they have to be cooled back, an appropriate evaluation is given taking environmental parameters into account. The dielectric strength of vacuum interrupters is considered both at ambient temperature as well as directly in liquid nitrogen. For this purpose different contact distances are set at different interrupter types. A distinction is made between internal and external dielectric strength. Conditioning and deconditioning effects are minimized by an appropriate choice of the test circuit. The current chopping and resulting overvoltages are considered to be one of the few drawbacks of vacuum switching technology. Using a practical test circuit the height of chopping current is determined and compared for different temperatures. Due to strong scattering the evaluation is done using statistical methods. At

  5. Research on perception of quality and interruption costs for customers of high and medium voltage; Pesquisa sobre percepcao da qualidade e custos de interrupcao em clientes de alta e media tensao

    Energy Technology Data Exchange (ETDEWEB)

    Pelegrini, Marcelo A.P.; Almeida, Carlos Frederico Mechini; Baldan, Silvio; Amasifen, Juan C. Cebrian; Cunha, Gabriel R.A.; Garcia, Valdomiro V.; Cyrillo, Ivo O.; Souza, Tiago P. de; Magalhaes, Cecilia H. Magalhaes; Silva, Fabiana A. Toledo [Sinapsis Inovacao em Energia S/S LTDA, Bela Vista, SP (Brazil)], E-mails: marcelo.pelegrini@sinapsienergia.com, carlos.almeida, juan.cebrian@sinapsienergia.com

    2011-10-15

    This paper presents partial results of an applied research on the perceived quality of energy by customers of AES Eletropaulo of high and medium voltage. In general, occurrences related to power interruption can cause serious consequences for industrial and commercial customers. This issue motivated the calculation, from the results obtained, of the cost of interruption incurred by customers individually, based on 12 categories of spending, and this result was validated by comparison with actual expenditures incurred during an intervention in a large industrial customer. (author)

  6. Lead iron phosphate glass as a containment medium for disposal of high-level nuclear waste

    Science.gov (United States)

    Boatner, Lynn A.; Sales, Brian C.

    1989-01-01

    Lead-iron phosphate glasses containing a high level of Fe.sub.2 O.sub.3 for use as a storage medium for high-level radioactive nuclear waste. By combining lead-iron phosphate glass with various types of simulated high-level nuclear waste, a highly corrosion resistant, homogeneous, easily processed glass can be formed. For corroding solutions at 90.degree. C., with solution pH values in the range between 5 and 9, the corrosion rate of the lead-iron phosphate nuclear waste glass is at least 10.sup.2 to 10.sup.3 times lower than the corrosion rate of a comparable borosilicate nuclear waste glass. The presence of Fe.sub.2 O.sub.3 in forming the lead-iron phosphate glass is critical. Lead-iron phosphate nuclear waste glass can be prepared at temperatures as low as 800.degree. C., since they exhibit very low melt viscosities in the 800.degree. to 1050.degree. C. temperature range. These waste-loaded glasses do not readily devitrify at temperatures as high as 550.degree. C. and are not adversely affected by large doses of gamma radiation in H.sub.2 O at 135.degree. C. The lead-iron phosphate waste glasses can be prepared with minimal modification of the technology developed for processing borosilicate glass nuclear wasteforms.

  7. Automated tube voltage selection for radiation dose and contrast medium reduction at coronary CT angiography using 3{sup rd} generation dual-source CT

    Energy Technology Data Exchange (ETDEWEB)

    Mangold, Stefanie [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Eberhard-Karls University Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany); Wichmann, Julian L. [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt (Germany); Schoepf, U.J. [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Medical University of South Carolina, Division of Cardiology, Department of Medicine, Charleston, SC (United States); Poole, Zachary B.; Varga-Szemes, Akos; De Cecco, Carlo N. [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Canstein, Christian [Siemens Medical Solutions, Malvern, PA (United States); Caruso, Damiano [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); University of Rome ' ' Sapienza' ' , Department of Radiological Sciences, Oncology and Pathology, Rome (Italy); Bamberg, Fabian; Nikolaou, Konstantin [Eberhard-Karls University Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany)

    2016-10-15

    To investigate the relationship between automated tube voltage selection (ATVS) and body mass index (BMI) and its effect on image quality and radiation dose of coronary CT angiography (CCTA). We evaluated 272 patients who underwent CCTA with 3{sup rd} generation dual-source CT (DSCT). Prospectively ECG-triggered spiral acquisition was performed with automated tube current selection and advanced iterative reconstruction. Tube voltages were selected by ATVS (70-120 kV). BMI, effective dose (ED), and vascular attenuation in the coronary arteries were recorded. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Five-point scales were used for subjective image quality analysis. Image quality was rated good to excellent in 98.9 % of examinations without significant differences for proximal and distal attenuation (all p ≥.0516), whereas image noise was rated significantly higher at 70 kV compared to ≥100 kV (all p <.0266). However, no significant differences were observed in SNR or CNR at 70-120 kV (all p ≥.0829). Mean ED at 70-120 kV was 1.5 ± 1.2 mSv, 2.4 ± 1.5 mSv, 3.6 ± 2.7 mSv, 5.9 ± 4.0 mSv, 7.9 ± 4.2 mSv, and 10.7 ± 4.1 mSv, respectively (all p ≤.0414). Correlation analysis showed a moderate association between tube voltage and BMI (r =.639). ATVS allows individual tube voltage adaptation for CCTA performed with 3{sup rd} generation DSCT, resulting in significantly decreased radiation exposure while maintaining image quality. (orig.)

  8. Lead-iron phosphate glass as a containment medium for the disposal of high-level nuclear wastes

    Science.gov (United States)

    Boatner, L.A.; Sales, B.C.

    1984-04-11

    Disclosed are lead-iron phosphate glasses containing a high level of Fe/sub 2/O/sub 3/ for use as a storage medium for high-level radioactive nuclear waste. By combining lead-iron phosphate glass with various types of simulated high-level nuclear waste

  9. Controlling the optical bistability and transmission coefficient in a four-level atomic medium

    International Nuclear Information System (INIS)

    Asadpour, Seyyed Hossein; Eslami-Majd, Abdullah

    2012-01-01

    A novel four level atomic configuration is proposed for controlling the optical bistability and transmission coefficient with application on all-optical switching. Two circularly polarized components from a weak linearly-polarized probe beam are interacted separately by two transitions of this medium. A coherent coupling field has derived another atomic transition. It is demonstrated that the transmission coefficient of two orthogonally polarized beams at different frequencies can be achieved by adjusting the magnitude of the external magnetic field. It is found that the threshold of the optical bistability can be controlled by magnitude of the external magnetic field. Also, it is shown that optical bistability can be converted to optical multistability by switching the two orthogonally polarized beams. - Highlights: ► An inverted Y-type four level atomic system is proposed. ► Transmission coefficient can be controlled by a novel interesting parameter. ► Optical bistability and multistability can be achieved via external magnetic field. ► It is shown that our proposed model is suitable for all optical switching application.

  10. A capacitive level shifter for high voltage (2.5kV)

    DEFF Research Database (Denmark)

    Andersen, Thomas; Andersen, Michael A. E.; Thomsen, Ole Cornelius

    2012-01-01

    with focus on low power consumption as well as low capacitive load between the floating half-bridge node and ground (output capacitance). The operation of the level-shifter is tested and verified by measurements on a prototype half-bridge gate driver. Results conclude stabile operation at 2.44kV, 50k...

  11. Direct Power Control for Three-Phase Two-Level Voltage-Source Rectifiers Based on Extended-State Observation

    DEFF Research Database (Denmark)

    Song, Zhanfeng; Tian, Yanjun; Yan, Zhuo

    2016-01-01

    This paper proposed a direct power control strategy for three-phase two-level voltage-source rectifiers based on extended-state observation. Active and reactive powers are directly regulated in the stationary reference frame. Similar to the family of predictive controllers whose inherent...... characteristic is highly dynamic behaviors, the proposed control strategy can present comparably enhanced transient performance. Furthermore, excellent steady-state power performance can also be observed when the proposed control scheme is adopted. In addition, another attractive feature lies in its robust...... performance, facilitating the successful suppression of performance deterioration caused by parameter variations and model inaccuracy. Detailed frequency-domain analysis is provided to verify its effectiveness. Experimental comparisons are also carried out among the finite control set model direct power...

  12. New strategy for eliminating zero-sequence circulating current between parallel operating three-level NPC voltage source inverters

    DEFF Research Database (Denmark)

    Li, Kai; Dong, Zhenhua; Wang, Xiaodong

    2018-01-01

    buses, that are operating in parallel. First, an equivalent model of ZSCC in a three-phase three-level NPC inverter paralleled system is developed. Second, on the basis of the analysis of the excitation source of ZSCCs, i.e., the difference in common mode voltages (CMVs) between paralleled inverters......, the ZCMV-PWM method is presented to reduce CMVs, and a simple electric circuit is adopted to control ZSCCs and neutral point potential. Finally, simulation and experiment are conducted to illustrate effectiveness of the proposed strategy. Results show that ZSCCs between paralleled inverters can...... be eliminated effectively under steady and dynamic states. Moreover, the proposed strategy exhibits the advantage of not requiring carrier synchronization. It can be utilized in inverters with different types of filter....

  13. Quantitative evaluation of waste prevention on the level of small and medium sized enterprises (SMEs)

    International Nuclear Information System (INIS)

    Laner, David; Rechberger, Helmut

    2009-01-01

    Waste prevention is a principle means of achieving the goals of waste management and a key element for developing sustainable economies. Small and medium sized enterprises (SMEs) contribute substantially to environmental degradation, often not even being aware of their environmental effects. Therefore, several initiatives have been launched in Austria aimed at supporting waste prevention measures on the level of SMEs. To promote the most efficient projects, they have to be evaluated with respect to their contribution to the goals of waste management. It is the aim of this paper to develop a methodology for evaluating waste prevention measures in SMEs based on their goal orientation. At first, conceptual problems of defining and delineating waste prevention activities are briefly discussed. Then an approach to evaluate waste prevention activities with respect to their environmental performance is presented and benchmarks which allow for an efficient use of the available funds are developed. Finally the evaluation method is applied to a number of former projects and the calculated results are analysed with respect to shortcomings and limitations of the model. It is found that the developed methodology can provide a tool for a more objective and comprehensible evaluation of waste prevention measures

  14. Sol - gel inorganic ion exchangers for conditioning of medium level radioactive waste

    International Nuclear Information System (INIS)

    Arcangeli, G.; Traverso, D.M.; Gerontopoulos, P.; Fava, R.

    1988-01-01

    Decontamination of high-level liquid wastes and medium activity wastes streams by inorganic ion exchange combined with the conversion of the spent inorganic ion exchange material to waste ceramics presents a considerable potential for utilisation in waste conditioning. Ceramic waste forms are found superior to other candidate waste immobilisation forms but practical implementation is hampered because of the complexity of the related fabrication technology. This report shows the possibility of improving this situation by resorting to sol gel techniques earlier developed for preparation of nuclear fuel ceramics. The principal findings are: - superior quality ion exchange xerogel titanates in the form of mechanically resistant, size controlled microspheres can be prepared using a simple sol-gel technique; - the titanate particles can be also used as precursors in Evaporative Deposition on Xerogel Particles (EDXP) a new waste solidification process based on physical impregnation of the xerogel material with the waste liquid followed by evaporation; - waste loaded ion exchange microspheres can be converted to leach resistant ceramics by firing and/or cold pressing and sintering at 900 0 -1100 0 C; - sol-gel inorganic ion exchange and EDXP may find useful application in conditioning MAW streams. 44 figs., 43 refs

  15. Determination of 93Zr in medium and low level radioactive wastes from Brazilian nuclear power plants

    International Nuclear Information System (INIS)

    Oliveira, Thiago C.; Oliveira, Arno H.

    2015-01-01

    The majority of long-lived radionuclides produced in the nuclear power plants can be regarded as difficult-to-measure radionuclides (RDM), hence chemical separation is necessary before the nuclear measurement of them. The zirconium isotope 93 Zr is a long-lived pure β-particle-emitting radionuclide produced from 235 U fission and from neutron activation of the stable isotope 92 Zr and thus occurring as one of the radionuclides found in nuclear reactors. Due to its long half-life, 93 Zr is one of the radionuclides of interest for the performance of assessment studies of waste storage or disposal. Two different methodologies based on extractive resins and LSC and ICP-MS techniques that enables the 93 Zr determination in medium (ILW) and low level (LLW) radioactive wastes samples from Brazilian nuclear power plants has been developed in our laboratory. Analyzing real samples 65% and 75% chemical yields for 93 Zr recovery were achieved for ICP-MS and LSC techniques, respectively. The detection limits were 0.045 μg.L -1 for ICP-MS and 0.05 Bq.L -1 for LSC techniques. (author)

  16. Line C17: alpha and medium-level beta-gamma laboratory pilot facility

    International Nuclear Information System (INIS)

    Calor, J.N.; Mauborgne, B.; Montuir, M.

    2000-01-01

    The Process Development Laboratory (LDP) uses the ATALANTE C17 line for integral testing in order to develop and validate spent fuel reprocessing methods and for overall qualification of calculation codes. Line C 17 comprises shielded cells and glove boxes, equipped with centrifugal extractors and laboratory-scale mixer-settlers to test liquid-liquid extraction processes in an alpha and medium-level beta-gamma environment. The high reliability and precision of the process instrumentation and control system allow full control of operating parameters and comprehensive operating data recording, meeting the experimentation quality requirements necessary for qualifying calculation codes. Direct online spectrophotometric analysis at various points in the process provides real-time concentration data for vital elements, some of which are difficult to analyze offline because of their poor chemical stability. Online analyses, supplemented when necessary by gamma spectrometry, provide valuable process control input for reaching stabilized operating conditions. Fifteen radioactive test campaigns have been successfully completed since line C 17 was commissioned in June 1995. (authors)

  17. Indoor particle levels in small- and medium-sized commercial buildings in California.

    Science.gov (United States)

    Wu, Xiangmei May; Apte, Michael G; Bennett, Deborah H

    2012-11-20

    This study monitored indoor and outdoor particle concentrations in 37 small and medium commercial buildings (SMCBs) in California with three buildings sampled on two occasions, resulting in 40 sampling days. Sampled buildings included offices, retail establishments, restaurants, dental offices, and hair salons, among others. Continuous measurements were made for both ultrafine and fine particulate matter as well as black carbon inside and outside of the building. Integrated PM(2.5), PM(2.5-10), and PM(10) samples were also collected inside and outside the building. The majority of the buildings had indoor/outdoor (I/O) particle concentration ratios less than 1.0, indicating that contributions from indoor sources are less than removal of outdoor particles. However, some of the buildings had I/O ratios greater than 1, indicating significant indoor particle sources. This was particularly true of restaurants, hair salons, and dental offices. The infiltration factor was estimated from a regression analysis of indoor and outdoor concentrations for each particle size fraction, finding lower values for ultrafine and coarse particles than for submicrometer particles, as expected. The I/O ratio of black carbon was used as a relative measure of the infiltration factor of particles among buildings, with a geometric mean of 0.62. The contribution of indoor sources to indoor particle levels was estimated for each building.

  18. Nimbus-2 Level 2 Medium Resolution Infrared Radiometer (MRIR) V001

    Data.gov (United States)

    National Aeronautics and Space Administration — The Nimbus II Medium Resolution Infrared Radiometer (MRIR) was designed to measure electromagnetic radiation emitted and reflected from the earth and its atmosphere...

  19. A Three-Level Quasi-Two-Stage Single-Phase PFC Converter with Flexible Output Voltage and Improved Conversion Efficiency

    DEFF Research Database (Denmark)

    Tang, Yi; Zhu, Dexuan; Jin, Chi

    2015-01-01

    This paper presents a three-level quasi-two-stage single-phase power factor correction (PFC) converter that has flexible output voltage and improved conversion efficiency. The proposed PFC converter features sinusoidal input current, three-level output characteristic, and a wide range of output dc...

  20. Energy storage system in medium-sized voltage lines for the integration of decentralized fluctuating energy sources; Energiespeicher im Niederspannungsnetz zur Integration dezentraler, fluktuierender Energiequellen

    Energy Technology Data Exchange (ETDEWEB)

    Bodach, M.

    2006-06-30

    The solar radiation fluctuates due to atmospheric and planetary influences. Concerning PV systems, the changes from dark clouds to clear sky result in fast and very deep fluctuations of the time behaviour of the power output fed into the low voltage (LV) network by DC-AC-Converters. On the example of a daily recorded global radiation curve with a very short sampling time (regular interval time 1 s) the paper shows that short-term sags of the solar radiation are possible up to 80% of the previous value as a result of sudden and intensive changes of the density of the clouds. These disturbances of the quality of the generated electric power are directly transformed into the LV grids. If the number of PV systems connected to existing LV networks rises essentially, the fluctuating photovoltaic energy generation will achieve a very high importance and therefore not only the well-known, but also a lot of new problems will occur. They have already been investigated theoretically in different papers and they have also been proven quantitatively by own simulations. Improvements of the energy quality at the point of common coupling will be possible if the grid-coupled PV power plants are supplemented with suitable intelligent storage systems bridging the short-term sags. So the influence of the fluctuating radiation on the generated power can be fundamentally reduced. The developed intelligent short-term storage system smoothes out the generated power of the PV system by means of a storage. It is based on the very high capacity of an electric double layer (UltraCap, produced by EPCOS) and includes a complex electronic control system. The UltraCap has the required storing characteristics and has been adjusted to the system voltage by a highly sophisticated microprocessor controlled DC/DC-converter system. Such an intelligent storage system can also be used for the connection of other decentralised power generation units (e.g. fuel cells, block-unit heating power plant) to the

  1. Effect of Kerr-like medium on a two-level atom in interaction with bimodal oscillator

    Czech Academy of Sciences Publication Activity Database

    Abdalla, M. S.; Křepelka, Jaromír; Peřina, Jan

    2006-01-01

    Roč. 39, - (2006), s. 1563-1577 ISSN 0953-4075 R&D Projects: GA MŠk(CZ) OC P11.003 Institutional research plan: CEZ:AV0Z10100522 Keywords : kerr-like medium * two-level atom * bimodal oscillator Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.024, year: 2006

  2. Control and operation of power sources in a medium-voltage direct-current microgrid for an electric vehicle fast charging station with a photovoltaic and a battery energy storage system

    International Nuclear Information System (INIS)

    García-Triviño, Pablo; Torreglosa, Juan P.; Fernández-Ramírez, Luis M.; Jurado, Francisco

    2016-01-01

    Although electric vehicles (EVs) are experiencing a considerable upsurge, the technology associated with them is still under development. This study focused on the control and operation of a medium-voltage direct-current (MVDC) microgrid with an innovative decentralized control system, which was used as a fast charging station (FCS) for EVs. The FCS was composed of a photovoltaic (PV) system, a Li-ion battery energy storage system (BESS), two 48 kW fast charging units for EVs, and a connection to the local grid. With this configuration and thanks to its decentralized control, the FCS was able to work as a stand-alone system most of the time though with occasional grid support. This paper presents a new decentralized energy management system (EMS) with two options to control the power sources of the FCS. The choice of the power source depends on the MVDC bus voltage, the state-of-charge (SOC) of the BESS, and the control option of the EMS. This control was tested by simulating the FCS, when connected to several EVs and under different sun irradiance conditions. Simulation results showed that the FCS operated smoothly and effectively, which confirms the feasibility of using this technology in EVs. - Highlights: • This paper studies a MVDC microgrid for fast charging station of EV. • It is composed of a PV system, a BESS, two EV charging stations and a grid connection. • A decentralized control scheme is applied to control the power sources. • The MVDC bus voltage is the key parameter for controlling the system. • The results demonstrate the feasibility of the system and control under study.

  3. Less power outages thanks to shunt circuit breakers - Basic principle and experience gained in medium voltage networks with isolated neutral; Reduction des interruptions de fourniture grace au disjoncteur shunt. Principe et experimentation dans les reseaux moyenne tension a neutre isole

    Energy Technology Data Exchange (ETDEWEB)

    Raemy, E. de; Dutoit, J.

    2009-07-01

    The article presents the basic principle of the operation of shunt circuit breakers and reports on two years experience with such devices in the medium voltage (20 kV) distribution networks with isolated neutral of the 'Groupe E' electric utility in Western Switzerland. Shunt circuit breakers are devices that absorb the current of a phase for a few seconds in case this phase conductor encounters an insulation failure to the ground. In this way, electric arcs may be interrupted before they cause short circuits and, consequently, power outages. This is particularly useful in cable distribution networks. The article reports on the sophisticated criteria used to identify the default phase, since a simple criterion based on the voltage difference to the ground may be misleading. The experiments made in the networks under operation are reported in detail. They included all possible types of insulation failures that may occur in the practice. The statistics of the real failures encountered in the following two years of operation and the experience gained are also discussed. The authors conclude that shunt circuit breakers effectively avoid most power outages. The 'Groupe E' utility decided to immediately install such devices in its networks.

  4. High Efficiency Power Converter for Low Voltage High Power Applications

    DEFF Research Database (Denmark)

    Nymand, Morten

    The topic of this thesis is the design of high efficiency power electronic dc-to-dc converters for high-power, low-input-voltage to high-output-voltage applications. These converters are increasingly required for emerging sustainable energy systems such as fuel cell, battery or photo voltaic based......, and remote power generation for light towers, camper vans, boats, beacons, and buoys etc. A review of current state-of-the-art is presented. The best performing converters achieve moderately high peak efficiencies at high input voltage and medium power level. However, system dimensioning and cost are often...

  5. Quality management system for the disposal of low and medium levels radioactive wastes - RBMN

    International Nuclear Information System (INIS)

    Azevedo, Antonio Mario P.; Haucz, Maria Judite A.; Fraga, Rosane Rodrigues

    2011-01-01

    This article compares the standards applied in quality and safety management systems for the Disposal of Radioactive Waste. The comparison will be a contribution to development, maintenance and improvement the safety and quality system of a disposal of low and medium radioactive waste (RBMN) coordinated by CDTN - Brazilian Development Center for Nuclear Technology). (author)

  6. Correlation of proton irradiation induced threshold voltage shifts to deep level traps in AlGaN/GaN heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z.; Cardwell, D.; Sasikumar, A.; Arehart, A. R.; Ringel, S. A., E-mail: ringel.5@osu.edu [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Kyle, E. C. H.; Speck, J. S. [Department of Materials, University of California, Santa Barbara, California 93106-5050 (United States); Chen, J.; Zhang, E. X.; Fleetwood, D. M.; Schrimpf, R. D. [Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37235 (United States)

    2016-04-28

    The impact of proton irradiation on the threshold voltage (V{sub T}) of AlGaN/GaN heterostructures is systematically investigated to enhance the understanding of a primary component of the degradation of irradiated high electron mobility transistors. The value of V{sub T} was found to increase monotonically as a function of 1.8 MeV proton fluence in a sub-linear manner reaching 0.63 V at a fluence of 1 × 10{sup 14} cm{sup −2}. Silvaco Atlas simulations of V{sub T} shifts caused by GaN buffer traps using experimentally measured introduction rates, and energy levels closely match the experimental results. Different buffer designs lead to different V{sub T} dependences on proton irradiation, confirming that deep, acceptor-like defects in the GaN buffer are primarily responsible for the observed V{sub T} shifts. The proton irradiation induced V{sub T} shifts are found to depend on the barrier thickness in a linear fashion; thus, scaling the barrier thickness could be an effective way to reduce such degradation.

  7. Correlation of proton irradiation induced threshold voltage shifts to deep level traps in AlGaN/GaN heterostructures

    Science.gov (United States)

    Zhang, Z.; Cardwell, D.; Sasikumar, A.; Kyle, E. C. H.; Chen, J.; Zhang, E. X.; Fleetwood, D. M.; Schrimpf, R. D.; Speck, J. S.; Arehart, A. R.; Ringel, S. A.

    2016-04-01

    The impact of proton irradiation on the threshold voltage (VT) of AlGaN/GaN heterostructures is systematically investigated to enhance the understanding of a primary component of the degradation of irradiated high electron mobility transistors. The value of VT was found to increase monotonically as a function of 1.8 MeV proton fluence in a sub-linear manner reaching 0.63 V at a fluence of 1 × 1014 cm-2. Silvaco Atlas simulations of VT shifts caused by GaN buffer traps using experimentally measured introduction rates, and energy levels closely match the experimental results. Different buffer designs lead to different VT dependences on proton irradiation, confirming that deep, acceptor-like defects in the GaN buffer are primarily responsible for the observed VT shifts. The proton irradiation induced VT shifts are found to depend on the barrier thickness in a linear fashion; thus, scaling the barrier thickness could be an effective way to reduce such degradation.

  8. Correlation of proton irradiation induced threshold voltage shifts to deep level traps in AlGaN/GaN heterostructures

    International Nuclear Information System (INIS)

    Zhang, Z.; Cardwell, D.; Sasikumar, A.; Arehart, A. R.; Ringel, S. A.; Kyle, E. C. H.; Speck, J. S.; Chen, J.; Zhang, E. X.; Fleetwood, D. M.; Schrimpf, R. D.

    2016-01-01

    The impact of proton irradiation on the threshold voltage (V T ) of AlGaN/GaN heterostructures is systematically investigated to enhance the understanding of a primary component of the degradation of irradiated high electron mobility transistors. The value of V T was found to increase monotonically as a function of 1.8 MeV proton fluence in a sub-linear manner reaching 0.63 V at a fluence of 1 × 10 14  cm −2 . Silvaco Atlas simulations of V T shifts caused by GaN buffer traps using experimentally measured introduction rates, and energy levels closely match the experimental results. Different buffer designs lead to different V T dependences on proton irradiation, confirming that deep, acceptor-like defects in the GaN buffer are primarily responsible for the observed V T shifts. The proton irradiation induced V T shifts are found to depend on the barrier thickness in a linear fashion; thus, scaling the barrier thickness could be an effective way to reduce such degradation.

  9. Admissibility of building cost subsidy in the power grid above the low voltage level; Zulaessigkeit von Baukostenzuschuessen im Stromnetz oberhalb der Niederspannungsebene

    Energy Technology Data Exchange (ETDEWEB)

    Foerster, Sven [Kanzlei Norton Rose Fulbright LLP, Muenchen(Germany)

    2015-07-01

    Electricity networks are essential to the provision of electrical power to businesses and individuals. In particular for manufacturing businesses a connection to the grid above the low-voltage level is often useful. Network operators demand a subsidy for the new connection and for the change to a higher network level under the auspices of construction cost. The power network market above the low-voltage level is a natural monopoly. This leaves consumers looking for a connection to the power grid with no possibility to select among different network operators. Construction cost subsidies are not regulated by law above the low voltage level. The lack of legal regulation and the natural monopoly above the low-voltage level affect the balance of power between network operators and system users. The lawfulness of the construction cost subsidies, the prerequisites for their demand and a review of the calculation models (Leistungspreismodell, 2-Ebenen-Modell) as well as a proposal for a reform of this system form the subject of this work.

  10. High voltage test techniques

    CERN Document Server

    Kind, Dieter

    2001-01-01

    The second edition of High Voltage Test Techniques has been completely revised. The present revision takes into account the latest international developments in High Voltage and Measurement technology, making it an essential reference for engineers in the testing field.High Voltage Technology belongs to the traditional area of Electrical Engineering. However, this is not to say that the area has stood still. New insulating materials, computing methods and voltage levels repeatedly pose new problems or open up methods of solution; electromagnetic compatibility (EMC) or components and systems al

  11. Voltage Management in Unbalanced Low Voltage Networks Using a Decoupled Phase-Tap-Changer Transformer

    DEFF Research Database (Denmark)

    Coppo, Massimiliano; Turri, Roberto; Marinelli, Mattia

    2014-01-01

    The paper studies a medium voltage-low voltage transformer with a decoupled on load tap changer capability on each phase. The overall objective is the evaluation of the potential benefits on a low voltage network of such possibility. A realistic Danish low voltage network is used for the analysis...

  12. Stray voltage mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Jamali, B.; Piercy, R.; Dick, P. [Kinetrics Inc., Toronto, ON (Canada). Transmission and Distribution Technologies

    2008-04-09

    This report discussed issues related to farm stray voltage and evaluated mitigation strategies and costs for limiting voltage to farms. A 3-phase, 3-wire system with no neutral ground was used throughout North America before the 1930s. Transformers were connected phase to phase without any electrical connection between the primary and secondary sides of the transformers. Distribution voltage levels were then increased and multi-grounded neutral wires were added. The earth now forms a parallel return path for the neutral current that allows part of the neutral current to flow continuously through the earth. The arrangement is responsible for causing stray voltage. Stray voltage causes uneven milk production, increased incidences of mastitis, and can create a reluctance to drink water amongst cows when stray voltages are present. Off-farm sources of stray voltage include phase unbalances, undersized neutral wire, and high resistance splices on the neutral wire. Mitigation strategies for reducing stray voltage include phase balancing; conversion from single to 3-phase; increasing distribution voltage levels, and changing pole configurations. 22 refs., 5 tabs., 13 figs.

  13. Effect of reduced x-ray tube voltage, low iodine concentration contrast medium, and sinogram-affirmed iterative reconstruction on image quality and radiation dose at coronary CT angiography: results of the prospective multicenter REALISE trial.

    Science.gov (United States)

    Yin, Wei-Hua; Lu, Bin; Gao, Jian-Bo; Li, Pei-Ling; Sun, Kai; Wu, Zhi-Feng; Yang, Wen-Jie; Zhang, Xiao-Qin; Zheng, Min-Wen; McQuiston, Andrew D; Meinel, Felix G; Schoepf, Uwe Joseph

    2015-01-01

    Both low tube voltage and sinogram-affirmed iterative reconstruction (IR) techniques hold promise to decrease radiation dose at coronary CT angiography (CCTA). The increased iodine contrast at low tube voltage allows for minimizing iodine load. To assess the effect of reduced x-ray tube voltage, low iodine concentration contrast medium and IR on image quality and radiation dose at CCTA. Two hundred thirty-one consecutive patients with suspected coronary artery disease were enrolled in this prospective, multicenter trial and randomized to 1 of 2 dual-source CCTA protocols: 120-kVp with 370 mgI/mL iopromide or iopamidol (n = 116; 44 women; 55.3 ± 9.8 years) or 100 kVp with 270 mgI/mL iodixanol (n = 115; 48 women; 54.2 ± 10.4 years). Reconstruction was performed with filtered back projection and IR. Attenuation, image noise, signal-to-noise ratio, and contrast-to-noise ratio were measured and image quality scored. Size-specific dose estimates and effective doses were calculated. There were no significant differences in mean arterial attenuation (406.6 ± 76.7 vs 409.7 ± 65.2 Hounsfield units; P = .739), image noise (18.7 ± 3.8 vs 17.9 ± 3.4 Hounsfield units; P = .138), signal-to-noise ratio (22.5 ± 5.4 vs 23.7 ± 6.1; P = .126), contrast-to-noise ratio (17.5 ± 5.5 vs 18.3 ± 6.1; P = .286), or image quality scores (4.1 ± 0.9 vs 4.0 ± 0.9; P > .05) between 120-kVp filtered back projection-reconstructed and 100-kVp IR-reconstructed series. Mean iodine dose was 26.5% lower (18.3 ± 0.5 vs 24.9 ± 0.9 g; P x-ray tube voltage and IR allows for decreasing the iodine load and effective radiation dose at CCTA while maintaining image quality. Copyright © 2015 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

  14. Comparison of three-phase three-level voltage source inverter with intermediate dc–dc boost converter and quasi-Z-source inverter

    DEFF Research Database (Denmark)

    Panfilov, Dmitry; Husev, Oleksandr; Blaabjerg, Frede

    2016-01-01

    This study compares a three-phase three-level voltage source inverter with an intermediate dc-dc boost converter and a quasi-Z-source inverter in terms of passive elements values and dimensions, semiconductor stresses, and overall efficiency. A comparative analysis was conducted with relative...

  15. A transient simulation approach to obtaining capacitance-voltage characteristics of GaN MOS capacitors with deep-level traps

    Science.gov (United States)

    Fukuda, Koichi; Asai, Hidehiro; Hattori, Junichi; Shimizu, Mitsuaki; Hashizume, Tamotsu

    2018-04-01

    In this study, GaN MOS capacitance-voltage device simulations considering various interface and bulk traps are performed in the transient mode. The simulations explain various features of capacitance-voltage curves, such as plateau, hysteresis, and frequency dispersions, which are commonly observed in measurements of GaN MOS capacitors and arise from complicated combinations of interface and bulk deep-level traps. The objective of the present study is to provide a good theoretical tool to understand the physics of various nonideal measured curves.

  16. Multi-objective optimization of distributed generation with voltage ...

    African Journals Online (AJOL)

    DR OKE

    The technical impact on medium-voltage level reliability as well as electrical power quality is assessed and used distribution system impact indices. (Ochoa et al, 2008), present a multi-objective performance index for distribution systems with time-varying distributed generation and load, considering a number of issues such ...

  17. Numerical simulations of mechanical and ignition-deflagration responses for PBXs under low-to-medium-level velocity impact loading.

    Science.gov (United States)

    Yang, Kun; Wu, Yanqing; Huang, Fenglei; Li, Ming

    2017-09-05

    An effective computational model is required to accurately predict the dynamic responses in accidental initiations of explosives. The present work uses a series of two-dimensional mechanical-chemical simulations performed via a hydrodynamic-code, DREXH-2D, to efficiently describe the mechanical and ignition-deflagration responses of cased cylindrical polymer-bonded explosives (PBXs) undergoing a low-to-medium-level impact (70-350m/s) in longitudinal direction. The ignition response was predicted based on an ignition criterion of effective plastic work. Slow burning and its growth to deflagration were described through a pressure-dependent reaction rate equation. The extreme value of effective plastic work was found to be useful to determine the ignition threshold velocity for PBXs. For low-level velocity impact, the incident stress wave reflection from lateral surfaces contributed to the formation of ignition regions. After the ignition, the deflagration was induced in the medium-level impact, and its violence was related to the shock strength. However, the low-strength stress wave only induced reaction at local regions, and sequent burning was no longer sensitive to the strength of incident wave. The predicted pressure and temperature results of PBXs were consistent with the medium-level impact tests performed by China Academy of Engineering Physics. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. On the Performance Optimization of Two-Level Three-Phase Grid-Feeding Voltage-Source Inverters

    Directory of Open Access Journals (Sweden)

    Issam A. Smadi

    2018-02-01

    Full Text Available The performance optimization of the two-level, three-phase, grid-feeding, voltage-source inverter (VSI is studied in this paper, which adopts an online adaptive switching frequency algorithm (OASF. A new degree of freedom has been added to the employed OASF algorithm for optimal selection of the weighting factor and overall system optimization design. Toward that end, a full mathematical formulation, including the impact of the coupling inductor and the controller response time, is presented. At first, the weighting factor is selected to favor the switching losses, and the controller gains are optimized by minimizing the integral time-weighted absolute error (ITAE of the output active and reactive power. Different loading and ambient temperature conditions are considered to validate the optimized controller and its fast response through online field programmable gate array (FPGA-in-the-loop. Then, the weighting factor is optimally selected to reduce the cost of the L-filter and the heat-sink. An optimization problem to minimize the cost design at the worst case of loading condition for grid-feeding VSI is formulated. The results from this optimization problem are the filter inductance, the thermal resistance of the heat-sink, and the optimal switching frequency with the optimal weighting factor. The VSI test-bed using the optimized parameters is used to verify the proposed work experimentally. Adopting the OASF algorithm that employs the optimal weighting factor for grid-feeding VSI, the percentages of the reductions in the slope of the steady state junction temperature profile compared to fixed frequencies of 10 kHz, 14.434 kHz, and 20 kHz are about 6%, 30%, and 18%, respectively.

  19. Evaluation of Multi Predictive Controllers for a Two-Level Three-Phase Stand-Alone Voltage Source Converter

    DEFF Research Database (Denmark)

    Al hasheem, Mohamed; Dragicevic, Tomislav; Blaabjerg, Frede

    2017-01-01

    This paper discusses a model predictive control (MPC), which is used usually in voltage and current control in a three phase voltage source converter (VSC). Moreover, a discrete model of the three-phase converter system with associated \\textit{LC} filer is used by the predictive control....... The controller predicts the values of the system variables. The errors between the references and the predicted values are evaluated by a cost function (CF). Simulation results of the different cost functions are presented. In addition, a multi-steps prediction scheme is also used in order to validate...

  20. Overmodulation of n-level three-leg DC-AC diode-clamped converters with comprehensive capacitor voltage balance

    DEFF Research Database (Denmark)

    Busquets-Monge, S.; Maheshwari, Ram Krishan; Munk-Nielsen, Stig

    2013-01-01

    This paper presents a novel PWM strategy for nlevel three-leg semiconductor-clamped dc-ac converters in the overmodulation region, with dc-link capacitor voltage balance in every switching cycle. The strategy is based on the virtual-vector concept. Suitable reference vector trajectories are selec......This paper presents a novel PWM strategy for nlevel three-leg semiconductor-clamped dc-ac converters in the overmodulation region, with dc-link capacitor voltage balance in every switching cycle. The strategy is based on the virtual-vector concept. Suitable reference vector trajectories...

  1. The geology of some United Kingdom nuclear sites related to the disposal of low and medium level radioactive wastes

    International Nuclear Information System (INIS)

    Robins, N.S.

    1980-06-01

    The geological sequences beneath a further twelve nuclear sites in Britain are predicted from available data. Formations that are potentially suitable hosts for low and medium-level radioactive waste are identified and their relative merits assessed. Of the sites investigated, formations beneath six afford little or no potential, formations beneath a further 4 offer only moderate potential and sites underlain by the most favourable formations are Dungeness and Hinkley Point. (author)

  2. The geology of some United Kingdom nuclear sites related to the disposal of low and medium level radioactive wastes

    International Nuclear Information System (INIS)

    Robins, N.S.

    1980-04-01

    The geological sequences beneath ten British nuclear sites are extrapolated from the available data. Formations that are potentially suitable hosts for low and medium level radioactive waste are identified and their relative merits assessed. Of the sites investigated, formations beneath five afford little or no potential, formations beneath a further three offer only moderate potential and sites underlain by the most favourable formations are at Dounreay and Harwell. (author)

  3. Instantaneous Real-Time Kinematic Decimeter-Level Positioning with BeiDou Triple-Frequency Signals over Medium Baselines

    Directory of Open Access Journals (Sweden)

    Xiyang He

    2015-12-01

    Full Text Available Many applications, such as marine navigation, land vehicles location, etc., require real time precise positioning under medium or long baseline conditions. In this contribution, we develop a model of real-time kinematic decimeter-level positioning with BeiDou Navigation Satellite System (BDS triple-frequency signals over medium distances. The ambiguities of two extra-wide-lane (EWL combinations are fixed first, and then a wide lane (WL combination is reformed based on the two EWL combinations for positioning. Theoretical analysis and empirical analysis is given of the ambiguity fixing rate and the positioning accuracy of the presented method. The results indicate that the ambiguity fixing rate can be up to more than 98% when using BDS medium baseline observations, which is much higher than that of dual-frequency Hatch-Melbourne-Wübbena (HMW method. As for positioning accuracy, decimeter level accuracy can be achieved with this method, which is comparable to that of carrier-smoothed code differential positioning method. Signal interruption simulation experiment indicates that the proposed method can realize fast high-precision positioning whereas the carrier-smoothed code differential positioning method needs several hundreds of seconds for obtaining high precision results. We can conclude that a relatively high accuracy and high fixing rate can be achieved for triple-frequency WL method with single-epoch observations, displaying significant advantage comparing to traditional carrier-smoothed code differential positioning method.

  4. Short- and Medium-Term Effects of Low-Level Laser Therapy on Periodontal Status in Lingual Orthodontic Patients.

    Science.gov (United States)

    Abellán, Rosa; Gómez, Clara; Oteo, María Dolores; Scuzzo, Giuseppe; Palma, Juan Carlos

    2016-07-01

    The purpose of this study was to evaluate the short- and medium-term effects of low-level laser therapy (LLLT) applied in repeated doses in adults with a healthy periodontium treated by lingual orthodontic appliances. Plaque accumulation, in combination with difficulty in removing it in lingual orthodontic patients, can cause gingival inflammation. Twelve orthodontic patients scheduled for fixed lingual orthodontic treatment were selected. Clinical measurements [visible plaque index (VPI), bleeding on probing (BOP), and probing depth (PD), and collection of gingival crevicular fluid (GCF)], which was used to measure the levels of interleukin-1beta (IL-1β) and tumor necrosis factor alpha (TNF-α), was performed before bonding the lingual device, and at the short-term (1, 2, 3 months) and medium-term (12 months) follow-up appointments. For each patient, quadrant 1 or 2 was randomly chosen for irradiation by a diode laser (λ = 670 nm, 190 mW, 6.05 W/cm(2), 60 sec/ tooth) (Laser Group) and the contralateral quadrant was used as the Control Group. In both studied groups, a slight worsening of the periodontal condition was observed, which was evident at the 3rd month follow-up and which was mainly at the lingual side in the Control Group. The levels of IL-1β in the GCF were significantly increased in the Control Group compared with the Laser Group at the 2nd and 3rd months after bonding. At the 12th month follow-up, an improvement of the inflammation was observed in both groups in the study. LLLT showed short-term effects by preventing a substantial increase in IL-1β levels. At medium-term follow-up, LLLT diminished VPI, BOP, and PD scores.

  5. Development and fabrication process for ZnO based varistors for medium voltage arresters 13000 V to 34000 V; Desarrollo y produccion de varistores de ZnO dopados para media tension 13000 V a 34000 V

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Rolon, B.; Ireta Moreno, F. [Facultad de Ingenieria Mecanica, Electrica y Electronica, Universidad de Guanajuato, Salamanca, Guanajuato (Mexico)]. E-mail: barbara@salamanca.ugto.mx; fireta@salamanca.ugto.mx

    2011-04-15

    The fabrication process for ZnO doped varistor blocks with Sb2O3/ Bi2O3 to medium tension of 13000 V to 34000 V, and was optimised in terms of a starting composition and firing temperatures with amounts for Sb2O3/ Bi2O3 ratios of 1.7 by dry pressing, and fired in the temperature 1150 degrees Celsius {+-}2 degrees Celsius. The microstructure characteristics were analysed across the surface of the varistor blocks in order to evaluate their microstructure homogeneity. Their current-voltage I-V and energy handling capabilities were also determined. Characteristics and electrical properties of the varistor blocks are discussed. [Spanish] El proceso de fabricacion para varistores de media tension de 13000 V a 34000 V de ZnO consistio en dopar con Sb2O3, Bi2O3 y optimizarlos en terminos de la composicion de inicio, con una relacion de Sb2O3/Bi2O3 de 1.7, y el uso de aditivos para ceramicas, la temperatura de sinterizado fue de 1150 grados centigrados {+-}2 grados centigrados. Se investigo la homogeneidad de la microestructura. Se determinaron las propiedades electricas mediante la determinacion de la grafica I-V. Las caracteristicas electricas son discutidas.

  6. Diagnosis on line and off line of induction motors of low, medium and high voltage; Diagnostico en linea y fuera de linea de motores de induccion de baja, mediana y alta tension

    Energy Technology Data Exchange (ETDEWEB)

    Carvajal, Francisco Antonio; Ramirez, Jose Manuel; Arcos, Luis Fernando [Instituto de Investigaciones Electricas, Temixco, Morelos (Mexico)

    1999-07-01

    The induction motors of low, medium and high voltage are the electrical equipment of greatest application in industry. The importance which they have in the different productive processes does necessary to assure its operative continuity. The anticipated detection of a possible cause of fault allows to plan, with maintenance aims, the programmed removal of the motor. In this article are presented the results of the activities nowadays performed by Management of Electrical Equipment of the Instituto de Investigaciones Electricas (IIE) for the development and application of online diagnosis techniques for induction motors up to 13.8 kV. [Spanish] Los motores de induccion de baja, mediana y alta tension son los equipos eletricos de mayor aplicacion en la industria. La importancia que tienen en los diferentes procesos productivos hace necesario asegurar su continuidad operativa. La deteccion anticipada de una posible causa de falla permite planear, con fines de mantenimiento, la remocion programada del motor. En este articulo se presentan los resultados de las actividades que realiza actualmente la Gerencia de equipos Electricos del Instituto de investigaciones Electricas (IIE) para el desarrollo y la aplicacion de tecnicas de diagnostico en linea para motores de induccion de hasta 13.8 kV.

  7. Noise levels in primary schools of medium sized city in Greece.

    Science.gov (United States)

    Sarantopoulos, George; Lykoudis, Spyros; Kassomenos, Pavlos

    2014-06-01

    This study presents and evaluates noise levels recorded at 15 school complexes in order to describe the indoor as well as the outdoor acoustic environment of schools and gain insight on controlling factors. Noise levels at the roadside in front of the school, the schoolyard, and 41 classrooms, both occupied and unoccupied, were simultaneously and continuously recorded through the course of a daily timetable (08:20-13:10). The average speech noise level of teachers was separately measured for 1min periods. Indoor noise levels, in all cases, were much higher than internationally recommended values: LAeq,5min averaged 69.0dB in occupied classrooms, and 47.1dB in unoccupied ones. Average speech-to-noise ratio (SNR) was estimated to be 12.0dB(A) during teaching, whereas both indoor and outdoor noise levels were significantly elevated during break time and outdoor physical-educational activities. Corresponding measurements of indoor and outdoor noise suggest that noise from the outside (road and schoolyard) affects the background noise level in the classrooms, however in varying degrees, depending on the specific layout and road traffic characteristics. Using double glazing diminishes this effect. © 2013.

  8. Preliminary estimate of the costs involved in the implantation of a low and medium level radioactive waste repository in Brazil

    International Nuclear Information System (INIS)

    Branco, Otavio E.A.; Carvalho Filho, Carlos A.; Ferreira, Vinicius V.M.; Alves, Paulo R.R.

    2009-01-01

    One relevant subject in the decision making process linked to the implantation of a low and intermediate level waste (LILW) repository in Brazil is regarding to the project expected costs. It is important to estimate in a solid way the total and partial costs expected, considering each one of the enterprise implantation phases. This work shows an initial estimative of these costs, based on reports and papers that evaluate the implantation, operation, closure and post closure costs of radioactive LILW waste repositories. In the development of this research only the costs regarding to near surface repositories, or similar ones, were considered. The total cost was estimated as approximately 115 million dollars, considering the whole project lifetime as 300 years. Considering the repository start-up costs (site selection, licensing, project and construction), the total value is estimated as 48 million dollars (1600 dollars/m 3 ). It is important to emphasize that some cares should be taken when costs obtained from the acquired experience by another countries in the repositories development are analyzed. As example, the costs for disposal 1 m 3 of low and medium level radioactive waste vary significantly from one country to another, even when repositories with similar projects are compared. Also the total costs of construction and licensing are significantly higher when compared those ones from 'conventional' facilities with similar technological characteristics. Finally, although about a dozen low and medium level radioactive waste repository are operating in Europe, new projects should be faced, as the international practice demonstrate, as original developments. (author)

  9. Characterization of low and medium-level radioactive waste forms. Final report - 2nd Programme 1980-84

    International Nuclear Information System (INIS)

    Pottier, P.E.; Glasser, F.P.

    1986-01-01

    The European Communities Second R and D Programme 1980-84 'Management and Disposal of Radioactive Waste (Shared cost action)' included a closely coordinated research activity for the 'Characterization of low and medium-level radioactive waste forms'. This report summarizes the main results obtained during the five years of the programme by laboratories in seven European countries participating in the coordinated RandD efforts. Ten reference waste forms have been selected, based on the most important types of low and medium-level waste arisings and the three commonly used immobilization matrices: cement, bitumen and polymers. The investigated properties were mainly: waste-matrix compatibility, radiation effects, leaching behaviour, leached radionuclides speciation, microbiological resistance and thermal as well as mechanical properties. Extensive experimental results relevant for the qualification of waste products and for application in performance analysis are presented in this final report. The main conclusions are drawn for the confinement properties of these different waste forms. These conclusions have also shown the necessity of selecting several other reference waste forms for the continuation of this RandD action now being launched in the Third EC Programme 1985-89

  10. Experimental Results of a DC Bus Voltage Level Control for a Load-Controlled Marine Current Energy Converter

    Directory of Open Access Journals (Sweden)

    Johan Forslund

    2015-05-01

    Full Text Available This paper investigates three load control methods for a  marine current energy converter using a vertical axis current  turbine (VACT mounted on a permanent magnet synchronous generator  (PMSG. The three cases are; a fixed AC load, a fixed pulse width  modulated (PWM DC load and DC bus voltage control of a DC  load. Experimental results show that the DC bus voltage control  reduces the variations of rotational speed by a factor of 3.5 at the cost  of slightly increased losses in the generator and transmission lines.  For all three cases, the tip speed ratio \\(\\lambda\\ can be kept close to  the expected \\(\\lambda_{opt}\\. The power coefficient is estimated to be  0.36 at \\(\\lambda_{opt}\\; however, for all three cases, the average  extracted power was about \\(\\sim 19\\\\%. A maximum power point  tracking (MPPT system, with or without water velocity measurement,  could increase the average extracted power.

  11. Restoration of Low-Voltage Distribution Systems with Inverter-Interfaced DG Units

    DEFF Research Database (Denmark)

    Dietmannsberger, Markus; Wang, Xiongfei; Blaabjerg, Frede

    2018-01-01

    -area voltage collapse. This paper proposes a restoration strategy from zero voltage conditions for inverter-interfaced DG under islanded conditions. In the approach, a flexible and scalable Master DG inverter concept is introduced for distributed generations, where no communication is needed and an outage......The increasing share of distributed generation (DG) offers new chances in grid restoration of low-voltage distribution grids. Instead of relying on the transmission or high- and medium-voltage levels, establishing islanding operation in low-voltage grids might be a good option after a wide...... of the Master can be balanced by other DG inverters. The control strategy ensures the tracking of nominal values of the system voltage and frequency without zero steady-state error. The influences of non-controllable DG are also taken into account in the strategy with an effective countermeasure developed...

  12. Transient voltage sharing in series-coupled high voltage switches

    Directory of Open Access Journals (Sweden)

    Editorial Office

    1992-07-01

    Full Text Available For switching voltages in excess of the maximum blocking voltage of a switching element (for example, thyristor, MOSFET or bipolar transistor such elements are often coupled in series - and additional circuitry has to be provided to ensure equal voltage sharing. Between each such series element and system ground there is a certain parasitic capacitance that may draw a significant current during high-speed voltage transients. The "open" switch is modelled as a ladder network. Analy­sis reveals an exponential progression in the distribution of the applied voltage across the elements. Overstressing thus oc­curs in some of the elements at levels of the total voltage that are significantly below the design value. This difficulty is overcome by grading the voltage sharing circuitry, coupled in parallel with each element, in a prescribed manner, as set out here.

  13. Microbial Contamination Level Profiles Attributed to Contamination of Beef Carcasses, Personnel, and Equipment: Case of Small and Medium Enterprise Slaughterhouses.

    Science.gov (United States)

    Wambui, Joseph; Lamuka, Peter; Karuri, Edward; Matofari, Joseph; Njage, Patrick Murigu Kamau

    2018-04-01

    The microbial contamination level profiles (MCLPs) attributed to contamination of beef carcasses, personnel, and equipment in five Kenyan small and medium enterprise slaughterhouses were determined. Aerobic plate counts, Enterobacteriaceae, Staphylococcus, and Salmonella were used to determine contamination at four different slaughter stages, namely, dehiding, evisceration, splitting, and dispatch. Microbiological criteria of the four microorganisms were used to score contamination levels (CLs) as poor (0), poor to average (1), average (2), or good (3). MCLPs were further assigned to carcasses, personnel, and equipment at each stage by summing up the CL scores. The CL score attributed to aerobic plate count contamination was 2 or 3 for carcasses but 0 for personnel and equipment in almost all slaughterhouses. A score of 0 on carcasses was mostly attributed to Enterobacteriaceae at evisceration and to Salmonella at dehiding and evisceration. In addition, a score of 0 was mostly attributed to Staphylococcus contamination of personnel at dehiding. A score of 3 was attributed mostly to Enterobacteriaceae on hands at splitting, whereas a score of 2 was mostly attributed to the clothes at dehiding and evisceration. A CL score of 3 was mostly attributed to Enterobacteriaceae and Salmonella contamination of equipment at dehiding and splitting, respectively. Although CLs attributed to contamination of carcasses, personnel, and equipment ranged from 0 to 3, the maximum MCLP score of 9 was only attained in carcasses from two slaughterhouses at dehiding and from one slaughterhouse at dispatch. There is, therefore, a lot of room for small and medium enterprise slaughterhouses to improve their food safety objectives by improving food safety management systems at the points characterized by low CL scores.

  14. Surface disposal of low-level and medium-level short-lived waste. How safe is the disposal facility in Dessel in the long term?

    International Nuclear Information System (INIS)

    2014-01-01

    A disposal facility for the disposal of low-level and medium-level short-lived waste is planned to be built on a site located in the community of Dessel (Belgium). The facility will consist of 34 modules, corresponding to a storage volume capacity of approximately 70,000 m3. The disposal concept includes waste containers that are encapsulated in a concrete box which is filled with mortar. Approximately 900 of these blocks, or monoliths, fit inside each module. The article discusses the Research and Development programme that has been conducted at the Belgian Nuclear Research Center SCK-CEN in conjunction with the development of this facility. Main emphasis is on the models that have been developed for predicting the long-term containment of the disposal facility.

  15. Medium-spin levels and the character of the 20.4 ns 13/2+ isomer in 145Gd

    International Nuclear Information System (INIS)

    Pakkanen, A.; Muhonen, J.; Piiparinen, M.

    1981-06-01

    Levels of the N = 81 nucleus 145 Gd have been investigated by in-beam γ-ray and conversion electron spectroscopy with the 144 Sm( 3 He,2n) reaction. Fourteen new low- and medium-spin states between 1.0 and 2.4 MeV excitation, the known yrast levels up to spin (21/2) + , five other high-spin non-yrast states and a new 20.4 ns (13/2) + isomer at 2200.2 keV in 145 Gd have been observed. The isomer decays via a fast 927.3 keV E3 transition with B(E3) = 48 +- 7 W.u. Another weaker decay branch is a mixed, strongly hindered E1+M2+E3 transition to the νhsub(11/2)sup(-1) state. We propose an octupole νfsub(7/2)jsub(0)sup(-2)x3 - main configuration for the isomer, analogous to the 997 keV (13/2) + isomer in 147 Gd. The levels of 145 Gd are discussed on the basis of the spherical shell model. (author)

  16. Fluorescent labeling in semi-solid medium for selection of mammalian cells secreting high-levels of recombinant proteins

    Directory of Open Access Journals (Sweden)

    Garnier Alain

    2009-05-01

    Full Text Available Abstract Background Despite the powerful impact in recent years of gene expression markers like the green fluorescent protein (GFP to link the expression of recombinant protein for selection of high producers, there is a strong incentive to develop rapid and efficient methods for isolating mammalian cell clones secreting high levels of marker-free recombinant proteins. Recently, a method combining cell colony growth in methylcellulose-based medium with detection by a fluorescently labeled secondary antibody or antigen has shown promise for the selection of Chinese Hamster Ovary (CHO cell lines secreting recombinant antibodies. Here we report an extension of this method referred to as fluorescent labeling in semi-solid medium (FLSSM to detect recombinant proteins significantly smaller than antibodies, such as IGF-E5, a 25 kDa insulin-like growth factor derivative. Results CHO cell clones, expressing 300 μg/ml IGF-E5 in batch culture, were isolated more easily and quickly compared to the classic limiting dilution method. The intensity of the detected fluorescent signal was found to be proportional to the amount of IGF-E5 secreted, thus allowing the highest producers in the population to be identified and picked. CHO clones producing up to 9.5 μg/ml of Tissue-Plasminogen Activator (tPA, 67 kDa were also generated using FLSSM. In addition, IGF-E5 high-producers were isolated from 293SF transfectants, showing that cell selection in semi-solid medium is not limited to CHO and lymphoid cells. The best positive clones were collected with a micromanipulator as well as with an automated colony picker, thus demonstrating the method's high throughput potential. Conclusion FLSSM allows rapid visualization of the high secretors from transfected pools prior to picking, thus eliminating the tedious task of screening a high number of cell isolates. Because of its rapidity and its simplicity, FLSSM is a versatile method for the screening of high producers for

  17. A Double Phase-Shift Control Strategy for A Full-Bridge Three-Level DC/DC Converter

    DEFF Research Database (Denmark)

    Liu, Dong; Deng, Fujin; Gong, Zheng

    2016-01-01

    In this paper, a double phase-shift control strategy is proposed for the full-bridge three-level (FBTL) DC/DC converter applied into DC distribution systems with the medium DC bus voltage. By utilizing the proposed control strategy, the voltage change rate dv/dt and voltage stress of the transfor...

  18. Presentation of preliminary studies relative to the long duration disposal of medium level and long lived (MLLL) wastes

    International Nuclear Information System (INIS)

    Leroy, C.; Moreau, A.; Fayette, L.; Bellon, M.; Templier, J.C.; Macias, R.M.; Porcher, J.B.; Rey, F.; Hollender, F.; Girard, J.P.

    2002-01-01

    In the contract of objectives signed in 2001 with the government, the French atomic energy commission (CEA) committed itself to supply reports of preliminary studies about long duration disposal concepts for medium level and long lived radioactive wastes. This document makes the synthesis of the preliminary studies carried out in 2001 and 2002 by exploring simultaneously the surface and subsurface disposal concepts. The studies deal with the design of a facility with a long service life. Four hypotheses have been retained for the preliminary studies: a secular lifetime (typically 100 to 300 years), a single and new site for all waste packages (no existing facility available), two confinement barriers, an envelope-type site with specific characteristics (seismicity, climate conditions, airplane crash..). These preliminary studies show the existence of solutions for each option: with and without storage containers in both type (surface and subsurface) of facilities. They outline the necessity of studying more thoroughly some technical points. This instruction will be performed for the concepts retained after a multi-criteria analysis. (J.S.)

  19. Determination of {sup 93}Zr in medium and low level radioactive wastes from Brazilian nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Thiago C.; Oliveira, Arno H., E-mail: oliveiratco2010@gmail.com, E-mail: heeren@nuclear.ufmg.br [Universidade Federal de Minas Gerais (DEN/UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear; Kastner, Geraldo F.; Monteiro, Roberto Pellacani G., E-mail: rpgm@cdtn.br, E-mail: gfk@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    The majority of long-lived radionuclides produced in the nuclear power plants can be regarded as difficult-to-measure radionuclides (RDM), hence chemical separation is necessary before the nuclear measurement of them. The zirconium isotope {sup 93}Zr is a long-lived pure β-particle-emitting radionuclide produced from {sup 235}U fission and from neutron activation of the stable isotope {sup 92}Zr and thus occurring as one of the radionuclides found in nuclear reactors. Due to its long half-life, {sup 93}Zr is one of the radionuclides of interest for the performance of assessment studies of waste storage or disposal. Two different methodologies based on extractive resins and LSC and ICP-MS techniques that enables the {sup 93}Zr determination in medium (ILW) and low level (LLW) radioactive wastes samples from Brazilian nuclear power plants has been developed in our laboratory. Analyzing real samples 65% and 75% chemical yields for {sup 93}Zr recovery were achieved for ICP-MS and LSC techniques, respectively. The detection limits were 0.045 μg.L{sup -1} for ICP-MS and 0.05 Bq.L{sup -1} for LSC techniques. (author)

  20. Performance assessment of confinements for medium-level and α-contaminated waste Pacoma project Rock salt option

    International Nuclear Information System (INIS)

    Hirsekorn, R.P.; Nies, A.; Rausch, H.; Storck, R.

    1991-01-01

    In the framework of the European R and D programme on Management and storage of radioactive waste, Task 5 the project Performance assessment of confinement of medium-level and α-contaminated waste (Pacoma) was carried out. The overall objective of this project is the assessment of the consequences associated with deep disposal of radioactive waste in three types of geological formation. The objective of the present contribution to the Pacoma project is to develop and demonstrate procedures for radiological safety of repositories in salt domes. An analogue study has been performed by the Dutch energy research foundation ECN, where alternative disposal concepts in different salt formations were investigated. In the present report, how far appropriate choice of the repository design parameters can improve the whole system is discussed. The research covers deterministic calculations for three scenarios: the normal evolution scenario with subrosion of the salt dome, the combined brine intrusion scenario with brine intrusion from brine pockets and via an anhydrite vein, and the human intrusion scenario of solution mining of a storage cavern. For the combined brine intrusion scenario alternative waste inventories, different disposal concepts, variants of the layout of dams and sealings are investigated, and results obtained from variations of parameter values are discussed. Additionally, for this scenario comprehensive probabilistic calculations have been carried out with the help of a Monte Carlo simulation. Results are discussed in the form of an uncertainty analysis of the maximum dose and global sensitivity studies of system parameters

  1. Five-Phase Five-Level Open-Winding/Star-Winding Inverter Drive for Low-Voltage/High-Current Applications

    DEFF Research Database (Denmark)

    Padmanaban, Sanjeevi Kumar; Blaabjerg, Frede; Wheeler, Patrick

    2016-01-01

    for open-/star-winding loads. Elaborately, per phase of the VSI is built with one additional bi-directional switch (MOSFET/IGBT) and all five legs links to the neutral through two capacitors. The structure allows multilevel generation to five-level output with greater potential for fault tolerability under...

  2. Capacitor Voltages Measurement and Balancing in Flying Capacitor Multilevel Converters Utilizing a Single Voltage Sensor

    DEFF Research Database (Denmark)

    Farivar, Glen; Ghias, Amer M. Y. M.; Hredzak, Branislav

    2017-01-01

    This paper proposes a new method for measuring capacitor voltages in multilevel flying capacitor (FC) converters that requires only one voltage sensor per phase leg. Multiple dc voltage sensors traditionally used to measure the capacitor voltages are replaced with a single voltage sensor at the ac...... side of the phase leg. The proposed method is subsequently used to balance the capacitor voltages using only the measured ac voltage. The operation of the proposed measurement and balancing method is independent of the number of the converter levels. Experimental results presented for a five-level FC...

  3. The Interaction of a N-Type Four Level Atom with the Electromagnetic Field for a Kerr Medium Induced Intensity-Dependent Coupling

    Science.gov (United States)

    Othman, Anas; Yevick, David

    2018-01-01

    The interaction of a N-type four-level atom with a single field in the presence of an intensity-dependent coupling in a nonlinear Kerr medium is investigated. The exact analytic solution is obtained in the case that the atom and electromagnetic field are initially in a higher excited state and a coherent state, respectively. It is then demonstrated that effects such as nonclassical light generation, degree of entanglement stabilization, Kerr medium nonclassical control, and squeezed light are can be more efficiently implemented within this four-level framework than in many competing procedures. Additionally, inversion, linear entropy, Mandel Q-parameter and normal squeezing dynamics are examined.

  4. Single-carrier sinusoidal PWM-equivalent selective harmonic elimination for a five-level voltage source converter

    Energy Technology Data Exchange (ETDEWEB)

    Dahidah, Mohamed S.A. [School of Electrical and Electronic Engineering, The University of Nottingham, Malaysia Campus, Jalan Broga, 43500 Semenyih, Selangor (Malaysia); Agelidis, Vassilios G. [School of Electrical and Information Engineering, The University of Sydney, NSW (Australia)

    2008-11-15

    The paper presents a new variation of selective harmonic elimination pulse-width modulation (SHE-PWM) technique suitable for a high-power five-level converter used in constant frequency utility applications. The governing system of equations associated with the elimination of specific harmonics is defined based on an equal number of switching transitions when compared against the single-carrier sinusoidal PWM (SC-SPWM) technique. For this paper, it is assumed that the modulating signal (triangular carrier) of the equivalent SC-SPWM method has twenty per unit frequency. The switching transitions for every quarter period are therefore distributed between the converter levels according to the modulation index of SC-SPWM. It is confirmed that the proposed technique offers significantly higher converter bandwidth and higher dc bus utilization for the same switching transitions. Furthermore, the proposed SHE-PWM offers better harmonic performance compared to its SC-SPWM counterpart. Selected solutions for the switching transitions are presented and verified experimentally in order to confirm the effectiveness of the proposed technique. (author)

  5. Comparative study of test methods for bituminized and other low- and medium-level solidified waste materials

    International Nuclear Information System (INIS)

    Brodersen, K.; Mose Pedersen, B.; Vinther, A.

    1983-12-01

    Various aspects of the behaviour of bituminized or cemented simulated low- or medium-level radioactive waste in contact with water or salt solutions have been investigated. The solubility (approximately 0.5%) and the diffusion coefficient (approximately 5.10 -8 cm 2 /sec) determining transort of water in pure bitumen have been measured for Mexphalte 40/50 at room temperature. A weighing method has been used to study water uptake and swelling of bituminized sodium nitrate, sodium sulphate or cation-exchange resin. The swelling of samples in contact with water was in some cases very pronounced. In strong salt solutions the tendency to swell is much less. The particle size of the embedded waste material is an important parameter. Thermal pre-treatment of cation-exchange resin before bituminization does not seem to improve the quality of the final product. The interaction between bituminized-exchange resin and concrete barrier materials has been studied. Microbial degradation of bitumen and bituminized waste under aerobic conditions has been investigated. It is probably of minor importance as far as leaching is concerned. A method for measuring leaching from a plane surface of cemented waste has been developed. The method avoids the problem of cracks between the sample and the container. Leaching from cemented sodium nitrate or sulphate was investigated. Absorption of CO 2 from the atmosphere was found to have only minor effect on Cs- and Na-leaching but gave a pronounced decrease in Ca-leaching. The use of silica-fume as an additive to cemented sodium nitrate decreased the leach rate by a factor 4. (author)

  6. Sensitivity of on-resistance and threshold voltage to buffer-related deep level defects in AlGaN/GaN high electron mobility transistors

    International Nuclear Information System (INIS)

    Armstrong, Andrew M; Allerman, Andrew A; Baca, Albert G; Sanchez, Carlos A

    2013-01-01

    The influence of deep levels defects located in highly resistive GaN:C buffers on the on-resistance (R ON ) and threshold voltage (V th ) of AlGaN/GaN high electron mobility transistors (HEMTs) power devices was studied by a combined photocapacitance deep level optical spectroscopy (C-DLOS) and photoconductance deep level optical spectroscopy (G-DLOS) methodology as a function of electrical stress. Two carbon-related deep levels at 1.8 and 2.85 eV below the conduction band energy minimum were identified from C-DLOS measurements under the gate electrode. It was found that buffer-related defects under the gate shifted V th positively by approximately 10%, corresponding to a net areal density of occupied defects of 8 × 10 12 cm −2 . The effect of on-state drain stress and off-state gate stress on buffer deep level occupancy and R ON was also investigated via G-DLOS. It was found that the same carbon-related deep levels observed under the gate were also active in the access region. Off-state gate stress produced significantly more trapping and degradation of R ON (∼140%) compared to on-state drain stress (∼75%). Greater sensitivity of R ON to gate stress was explained by a more sharply peaked lateral distribution of occupied deep levels between the gate and drain compared to drain stress. The overall greater sensitivity of R ON compared to V th to buffer defects suggests that electron trapping is significantly greater in the access region compared to under the gate, likely due to the larger electric fields in the latter region. (invited paper)

  7. Evaluation of the corrosion of reinforced concrete designed for low and medium activity level radioactive waste containers

    International Nuclear Information System (INIS)

    Duffo, G.S.; Arva, E.A; Schulz, F.M; Vasquez, D.R

    2010-01-01

    The National Atomic Energy Commission of Argentina (CNEA) is responsible for the design and construction of a monolithic repository for the final disposal of low and medium level radioactive wastes. In order to ensure the protection of people and the environment, the useful life of the repository should be 300 years and the conceptual design selected is based on the use of multiple, independent and redundant barriers. These barriers consist mainly of reinforced concrete. This work aims to establish a methodology to determine the concrete's useful life, evaluating parameters of interest using chemical and electrochemical techniques. For this purpose, reinforced concrete test pieces were made with two formulations - blast furnace cement (BFC) and with BFC plus silica fume admixture (BFC+SF)- and in each of the test pieces segments of reinforcement were included. The development over time of the corrosion potential and speed were evaluated, together with the resistivity of the concrete in the test pieces exposed to the laboratory environment, with an average relative humidity of 50%, a condition that favors the carbonation process. The diffusion coefficients of aggressive species, such as chloride and carbon dioxide, were also determined in test pieces made with the two formulations. In the test pieces exposed to the laboratory environment the reinforcements embedded in the BFC+SF concrete showed a lower corrosion speed compared to the BFC concrete. These results agree with the lower values for the speeds of carbonation and of chloride diffusion that show that the concrete with BFC+SF is more resistant to incoming aggressive species compared with the BFC. A container prototype for mid-level radioactive wastes was built and outfitted with instruments in order to monitor the development over time of the corrosion speed of the reinforcement rods by using corrosion sensors developed by the group. The prototype, exposed to atmospheric conditions, was manufactured with BFC

  8. Probing the Energy Level Alignment and the Correlation with Open-Circuit Voltage in Solution-Processed Polymeric Bulk Heterojunction Photovoltaic Devices.

    Science.gov (United States)

    Yang, Qing-Dan; Li, Ho-Wa; Cheng, Yuanhang; Guan, Zhiqiang; Liu, Taili; Ng, Tsz-Wai; Lee, Chun-Sing; Tsang, Sai-Wing

    2016-03-23

    Energy level alignment at the organic donor and acceptor interface is a key to determine the photovoltaic performance in organic solar cells, but direct probing of such energy alignment is still challenging especially for solution-processed bulk heterojunction (BHJ) thin films. Here we report a systematic investigation on probing the energy level alignment with different approaches in five commonly used polymer:[6,6]-phenyl-C71-butyric acid methyl ester (PCBM) BHJ systems. We find that by tuning the weight ratio of polymer to PCBM the electronic features from both polymer and PCBM can be obtained by photoemission spectroscopy. Using this approach, we find that some of the BHJ blends simply follow vacuum level alignment, but others show strong energy level shifting as a result of Fermi level pinning. Independently, by measuring the temperature-dependent open-circuit voltage (VOC), we find that the effective energy gap (Eeff), the energy difference between the highest occupied molecular orbital of the polymer donor (EHOMO-D) and lowest unoccupied molecular orbital of the PCBM acceptor (ELUMO-A), obtained by photoemission spectroscopy in all polymer:PCBM blends has an excellent agreement with the extrapolated VOC at 0 K. Consequently, the photovoltage loss of various organic BHJ photovoltaic devices at room temperature is in a range of 0.3-0.6 V. It is believed that the demonstrated direct measurement approach of the energy level alignment in solution-processed organic BHJ will bring deeper insight into the origin of the VOC and the corresponding photovoltage loss mechanism in organic photovoltaic cells.

  9. Voltage-Sharing Converter to Supply Single-Phase Asymmetrical Four-Level Diode-Clamped Inverter With High Power Factor Loads

    DEFF Research Database (Denmark)

    Boora, Arash A.; Nami, Alireza; Zare, Firuz

    2010-01-01

    of the load is close to unity. In this paper, a new single-inductor multi-output dc/dc converter is proposed that can control the dc-link voltages of a single-phase diode-clamped inverter asymmetrically to achieve voltage quality enhancement. The circuit of the presented converter is explained and the main...

  10. Voltage Controlled Dynamic Demand Response

    DEFF Research Database (Denmark)

    Bhattarai, Bishnu Prasad; Bak-Jensen, Birgitte; Mahat, Pukar

    2013-01-01

    Future power system is expected to be characterized by increased penetration of intermittent sources. Random and rapid fluctuations in demands together with intermittency in generation impose new challenges for power balancing in the existing system. Conventional techniques of balancing by large...... central or dispersed generations might not be sufficient for future scenario. One of the effective methods to cope with this scenario is to enable demand response. This paper proposes a dynamic voltage regulation based demand response technique to be applied in low voltage (LV) distribution feeders....... An adaptive dynamic model has been developed to determine composite voltage dependency of an aggregated load on feeder level. Following the demand dispatch or control signal, optimum voltage setting at the LV substation is determined based on the voltage dependency of the load. Furthermore, a new technique...

  11. Thermal Analysis of Multi-MW Two-Level Generator Side Converters with Reduced Common-Mode-Voltage Modulation Methods for Wind Turbines

    DEFF Research Database (Denmark)

    Qin, Zian; Liserre, Marco; Blaabjerg, Frede

    2013-01-01

    the thermal performance and common-mode voltage of the converter should be taken into account during the selection process of the modulation strategies. In this paper, based on the generator side converter of a 3 MW wind power system, the common-modevoltage reduced modulation strategies are compared......Thermal performance is one of the main indicators of power converter, since it is related to both the cost of cooling system and the reliability of the power converter. Moreover, the common-mode voltage in motor driver may damage the bearing of the motor and also cause failure. Therefore, both...... with the conventional-60o discontinuous PWM, where the common-mode voltage, power losses and thermal performance are all taken into account. In detail, the common-mode voltages are investigated both in time domain and spectrum. The power loss distribution of the power converter with the two modulation strategies...

  12. Hall voltage drives pulsing counter-currents of the sliding charge density wave and of quantized normal carriers at self-filled Landau levels

    Science.gov (United States)

    Orlov, Andrey P.; Sinchenko, Aleksander A.; Monceau, Pierre; Brazovskii, Serguei; Latyshev, Yuri I.

    2017-11-01

    Remnant pockets of carriers left over after formation of a charge density wave (CDW) were brought, by virtue of transverse electric and magnetic fields, to a current-carrying state at quantized Landau Levels. The generated Hall voltage polarizes and puts to sliding the flexible CDW background. The screening from the CDW allows for a so strong redistribution of normal electrons density under the action of the Lorentz force alone, that an integer filling of the lowest Landau level might be reached at one edge at the expense of the full depletion at another edge of the Hall bar. With the Hall field exceeding the sliding threshold, the regime of exactly compensated collective and normal counter-currents develops in the open-circuit direction across the bar. The annihilation of the two currents proceeds via a regular sequence of phase slips which are the space-time vortices of the CDW phase around the enforced amplitude nodes. The resulting spontaneous generation of coherent high ( GHz) frequency signals was detected by observations of multiple Shapiro steps. This picture results from studies of micron-sized Hall bars in crystals of NbSe3 prepared by means of focused ion beams. The interpretation is confirmed and illustrated by a numerical solution of the derived equations. The depinning pulse propagates from edges to the bulk and the sliding sets in, accompanied by the generation of periodic phase slips near the Hall bar edge where the CDW phase is advanced in steps of 2π at expense of the CDW amplitude passing through zero.

  13. Output pressure and harmonic characteristics of a CMUT as function of bias and excitation voltage

    DEFF Research Database (Denmark)

    Lei, Anders; Diederichsen, Søren Elmin; Hansen, Sebastian Molbech

    2015-01-01

    The large bandwidth makes CMUT based transducers interesting for both conventional and harmonic imaging. The inherent nonlinear behavior of the CMUT, however, poses an issue for harmonic imaging as it is difficult to dissociate the harmonics generated in the tissue from the harmonic content...... of the transmitted signal. The generation of intrinsic harmonics by the CMUT can be minimized by decreasing the excitation signal. This, however, leads to lower fundamental pressure which limits the desired generation of harmonics in the medium. This work examines the output pressure and harmonic characteristics...... of a CMUT as function of bias and excitation voltage. The harmonic to fundamental ratio of the surface pressures declines for decreasing excitation voltage and increasing bias voltage. The ratio, however, becomes unchanged for bias levels close to the pull-in voltage. The harmonic limitations of the CMUT...

  14. High-level secretion of a recombinant protein to the culture medium with a Bacillus subtilis twin-arginine translocation system in Escherichia coli.

    Science.gov (United States)

    Albiniak, Anna M; Matos, Cristina F R O; Branston, Steven D; Freedman, Robert B; Keshavarz-Moore, Eli; Robinson, Colin

    2013-08-01

    The twin-arginine translocation (Tat) system transports folded proteins across the plasma membrane in bacteria, and heterologous proteins can be exported by this pathway if a Tat-type signal peptide is present at the N-terminus. The system thus has potential for biopharmaceutical production in Escherichia coli, where export to the periplasm is often a favoured approach. Previous studies have shown that E. coli cells can export high levels of protein by the Tat pathway, and the protein product accummulates almost exclusively in the periplasm. In this study, we analysed E. coli cells that express the Bacillus subtilis TatAdCd system in place of the native TatABC system. We show that a heterologous model protein, comprising the TorA signal peptide linked to green fluorescent protein (TorA-GFP), is efficiently exported by the TatAdCd system. However, whereas the GFP is exported initially to the periplasm during batch fermentation, the mature protein is increasingly found in the extracellular culture medium. By the end of a 16-h fermentation, ~ 90% of exported GFP is present in the medium as active mature protein. The total protein profiles of the medium and periplasm are essentially identical, confirming that the outer membrane becomes leaky during the fermentation process. The cells are otherwise intact, and there is no large-scale release of cytoplasmic contents. Export levels are relatively high, with ~ 0.35 g GFP·L⁻¹ culture present in the medium. This system thus offers a means of producing recombinant protein in E. coli and harvesting directly from the medium, with potential advantages in terms of ease of purification and downstream processing. © 2013 FEBS.

  15. The dependence of efficiency of transmembrane molecular transfer using electroporation on medium viscosity.

    Science.gov (United States)

    Sungailaitė, Sandra; Ruzgys, Paulius; Šatkauskienė, Ingrida; Čepurnienė, Karolina; Šatkauskas, Saulius

    2015-01-01

    In the present study, we aimed to evaluate the efficiency of drug and gene electrotransfer into cells in vitro depending on medium viscosity. Experiments were performed using Chinese hamster ovary cells. Efficiency of molecular electrotransfer depending of medium viscosity was evaluated using two different electroporation conditions: a high-voltage (HV) pulse and a combination of a high-voltage pulse and a low-voltage pulse (HV + LV). To evaluate the efficiency of molecular electrotransfer, anticancer drug bleomycin and two different plasmids coding for green fluorescent protein and luciferase were used. We found that a slight increase in medium viscosity from 1.3-1.4 mPa·s significantly decreased the transfection efficiency, both in terms of transfected cells and total protein production, which was abolished completely with an increase in medium viscosity to 6.1 mPa·s. Notably, at this medium viscosity, electrotransfer of the small anticancer drug was still efficient. Using HV and HV + LV pulse combinations, we showed that a decrease of DNA electrotransfer, especially at lower medium viscosities, can be compensated for by the LV pulse to some extent. On the other hand, the addition of the LV pulse after the HV pulse did not have any positive effect on the efficiency of bleomycin electrotransfer. These findings demonstrate that transfection is very susceptible to medium viscosity and highlights the importance of the electrophoretic component in experiments when a considerable transfection level is needed. Copyright © 2015 John Wiley & Sons, Ltd.

  16. High voltage engineering. Fundamentals. 2. ed.

    Energy Technology Data Exchange (ETDEWEB)

    Kuffel, E. (ed.) [University of Manitoba, Winnipeg (Canada); Zaengl, W.S. (ed.) [Swiss Federal Institute of Technology, Zuric (Switzerland). Electrical Engineering Dept.; Kuffel, J. (ed.) [Ontario Hydro Technologies, Toronto (Canada)

    2000-07-01

    The basics of high voltage laboratory techniques and phenomena, together with the principles governing the design of high voltage insulation, are covered in this book for students studying high voltage engineering at both undergraduate and postgraduate level, utility engineers, designers and operators of high voltage equipment. In this new edition, the text has been entirely revised to reflect current practice. Major changes include coverage of the latest instrumentation, the use of electronegative gases such as sulphur hexafluoride, modern diagnostic techniques, and high voltage testing procedures with statistical approaches. (author)

  17. DVR(Dynamic Voltage Restorer)

    Indian Academy of Sciences (India)

    First page Back Continue Last page Graphics. DVR(Dynamic Voltage Restorer). Supply voltage Sag compensation. Supply voltage Swell Compensation. Balancing the Load voltage. Compensation of Supply Voltage Harmonics.

  18. The Dynamics of a Five-level (Double Λ)-type Atom Interacting with Two-mode Field in a Cross Kerr-like Medium

    Science.gov (United States)

    Obada, A.-S. F.; Ahmed, M. M. A.; Farouk, Ahmed M.

    2018-04-01

    In this paper, we propose a new transition scheme (Double Λ) for the interaction between a five-level atom and an electromagnetic field and study its dynamics in the presence of a cross Kerr-like medium in the exact-resonance case. The wave function is derived when the atom is initially prepared in its upper most state, and the field is initially prepared in the coherent state. We studied the atomic population inversion, the coherence degree by studying the second-order correlation function, Cauchy-Schwartz inequality (CSI) and the relation with P-function. Finally, we investigate the effect of Kerr-like medium on the evolution of Husimi Q-function of the considered system.

  19. The Dynamics of a Five-level (Double Λ)-type Atom Interacting with Two-mode Field in a Cross Kerr-like Medium

    Science.gov (United States)

    Obada, A.-S. F.; Ahmed, M. M. A.; Farouk, Ahmed M.

    2018-01-01

    In this paper, we propose a new transition scheme (Double Λ) for the interaction between a five-level atom and an electromagnetic field and study its dynamics in the presence of a cross Kerr-like medium in the exact-resonance case. The wave function is derived when the atom is initially prepared in its upper most state, and the field is initially prepared in the coherent state. We studied the atomic population inversion, the coherence degree by studying the second-order correlation function, Cauchy-Schwartz inequality (CSI) and the relation with P-function. Finally, we investigate the effect of Kerr-like medium on the evolution of Husimi Q-function of the considered system.

  20. A hierarchical model predictive voltage control for NPC/H-bridge converters with a reduced computational burden

    DEFF Research Database (Denmark)

    Gong, Zheng; Dai, Peng; Wu, Xiaojie

    2017-01-01

    In recent years, voltage source multilevel converters are very popular in medium/high-voltage industrial applications, among which the NPC/H-Bridge converter is a popular solution to the medium/high-voltage drive systems. The conventional finite control set model predictive control (FCS-MPC) stra......In recent years, voltage source multilevel converters are very popular in medium/high-voltage industrial applications, among which the NPC/H-Bridge converter is a popular solution to the medium/high-voltage drive systems. The conventional finite control set model predictive control (FCS...

  1. Loss and thermal redistributed modulation methods for three-level neutral-point-clamped wind power inverter undergoing Low Voltage Ride Through

    DEFF Research Database (Denmark)

    Ma, Ke; Blaabjerg, Frede

    2012-01-01

    investigates the loss and thermal performances of a 10 MW 3L-NPC wind power inverter undergoing Low Voltage Ride Through (LVRT) operation. A series of new space vector modulation methods are then proposed to relocate the thermal loading among the power switching devices. It is concluded that, with the proposed...

  2. High Voltage Power Converter for Large Wind Turbine

    DEFF Research Database (Denmark)

    Sztykiel, Michal

    system operates at 20 kV level - identical as for the collector distribution network. Medium voltage operation allows the converter unit along with the filter to be installed on the base platform inside the tower. In this manner, more space in the nacelle can be flexibly accommodated by the mechanical...... performance has been achieved by the transformer-less turbine with a back-to-back modular multilevel converter (MMC) topology, which is single grounded only through its DC link common-mode point. It has also occurred that the results derived from losses and short circuit analyses have become advantageous over...

  3. Voltage Support from Electric Vehicles in Distribution Grid

    DEFF Research Database (Denmark)

    Huang, Shaojun; Pillai, Jayakrishnan Radhakrishna; Bak-Jensen, Birgitte

    2013-01-01

    The paper evaluates the voltage support functions from electric vehicles (EVs) on a typical Danish distribution grid with high EV penetration. In addition to the popular voltage control modes, such as voltage droop charging (low voltage level leads to low charging power) and reactive power support...

  4. The Message is in the Data (not the Medium): Results From a Secondary-level Environmental Science Workshop

    Science.gov (United States)

    Fatland, D. R.

    2008-12-01

    I ran an extended (18 session) workshop during the 2007-2008 school year at a public Montessori elementary in Boulder Colorado. A reprise is running this year that extends to middle school students. The curriculum emphasis was on physical and environmental science, assembled in part using synoptic principles drawn from the National Research Council report "How People Learn". The curriculum was driven by story lines that began and ended in the students' zone of comprehension, in the interim extending through proximal development to open-ended inquiry. The workshop had four distinct purposes: i) Provide students an opportunity to problem-solve, ii) Break barriers between classroom learning and field science, iii) Determine what does and does not work with students at this age, iv) Begin building an alternative outreach path for professional scientists, specifically to avoid one-off presentation ('magic show') syndrome. New technology was incorporated in the workshop as needed--from thermochrons to virtual globes--but this was de- emphasized to keep focus on the subject matter. Data played a much stronger role particularly during early sessions where students were divided into 'phenomena' and 'scientist' groups in order to see both sides of the inquiry process. I present here workshop results, successes and failures, with two emphases: First on the idea that data can be an excellent way to build metacognitive skills in students around age 10. Second that-- with all due credit to Marshall McLuhan--the medium best serves by staying out of the way of the message.

  5. Observations and Predictions of Wave Runup, Extreme Water Levels, and Medium-Term Dune Erosion during Storm Conditions

    Directory of Open Access Journals (Sweden)

    Serge Suanez

    2015-07-01

    Full Text Available Monitoring of dune erosion and accretion on the high-energy macrotidal Vougot beach in North Brittany (France over the past decade (2004–2014 has revealed significant morphological changes. Dune toe erosion/accretion records have been compared with extreme water level measurements, defined as the sum of (i astronomic tide; (ii storm surge; and (iii vertical wave runup. Runup parameterization was conducted using swash limits, beach profiles, and hydrodynamic (Hm0, Tm0,–1, and high tide water level—HTWL data sets obtained from high frequency field surveys. The aim was to quantify in-situ environmental conditions and dimensional swash parameters for the best calibration of Battjes [1] runup formula. In addition, an empirical equation based on observed tidal water level and offshore wave height was produced to estimate extreme water levels over the whole period of dune morphological change monitoring. A good correlation between this empirical equation (1.01Hmoξo and field runup measurements (Rmax was obtained (R2 85%. The goodness of fit given by the RMSE was about 0.29 m. A good relationship was noticed between dune erosion and high water levels when the water levels exceeded the dune foot elevation. In contrast, when extreme water levels were below the height of the toe of the dune sediment budget increased, inducing foredune recovery. These erosion and accretion phases may be related to the North Atlantic Oscillation Index.

  6. Information entropy properties of the atoms in the system of coupled Λ-type three-level atoms interacting with coherent field in Kerr medium

    International Nuclear Information System (INIS)

    Li Ke; Ling Weijun

    2011-01-01

    The information entropy properties of the atoms of coupled Λ-type three-level atoms interacting with coherent field are studied by means of quantum theory, and discussed the time evolutions of the information entropy of the atoms via the average photon number, initial state of the atoms, detuning, coupling constant between the atoms and the coefficient of Kerr medium. Numerical calculation results show that the time evolutions of the information entropy properties of the atoms strongly dependent on the initial state of the system and the average photon number. Detuning, coupling constant between the atoms and the Kerr coefficient still make influence on the information entropy of the atoms. (authors)

  7. Influence of X and gamma radiation and bias conditions on dropout voltage of voltage regulators serial transistors

    International Nuclear Information System (INIS)

    Vukic, V.; Osmokrovic, P.; Stankovic, S.; Kovacevic, M.

    2005-01-01

    Research topic presented in this paper is degradation of characteristics of low-dropout voltage regulator's serial transistor during exposure of device to the ionizing radiation. Voltage regulators were exposed to X and γ radiation in two modes: without bias conditions, and with bias conditions and load. Tested circuits are representatives of the first and the second generation of low-dropout voltage regulators, with lateral and vertical PNP serial transistor: LM2940 and L4940. Experimental results of output voltage and serial dropout voltage change in function of total ionizing dose, during the medium-dose-rate exposure, were presented. (author) [sr

  8. Dysfunction of the Scn8a Voltage-gated Sodium Channel Alters Sleep Architecture, Reduces Diurnal Corticosterone Levels, and Enhances Spatial Memory

    OpenAIRE

    Papale, Ligia Assumpção [UNIFESP; Paul, Ketema N.; Sawyer, Nikki T.; Manns, Joseph R.; Tufik, Sergio [UNIFESP; Escayg, Andrew

    2010-01-01

    Voltage-gated sodium channels (VGSCs) are responsible for the initiation and propagation of transient depolarizing currents and play a critical role in the electrical signaling between neurons. A null mutation in the VGSC gene SCN8A, which encodes the transmembrane protein Na(v)1.6, was identified previously in a human family. Heterozygous mutation carriers displayed a range of phenotypes, including ataxia, cognitive deficits, and emotional instability. A possible role for SCN8A was also prop...

  9. NaCl concentration in the medium modulates the secretion of active EmpA protease in Vibrio anguillarum at post-transcriptional level.

    Science.gov (United States)

    Crisafi, F; Denaro, R; Yakimov, M; Felice, M R; Giuliano, L; Genovese, L

    2015-12-01

    This study focused on the influence of different amounts of NaCl in the medium in Vibrio anguillarum EmpA protease production at both the transcriptional and post-transcriptional levels. Vibrio anguillarum 975/I was cultivated in cM9 medium with varying concentrations of NaCl: 0·5, 1·5, 3·0%. EmpA protease was monitored in the supernatants by the skim milk test, azocasein assay and Western blot analysis. The empA gene expression was measured by real-time PCR. A mutant strain 975/I defective for the empA gene confirmed the specificity of the response for EmpA protease. Active protease production was induced by 0·5 and 1·5% NaCl-amended media; however, the strain cultivated in 3·0% NaCl was unable to secrete EmpA protease. The quantitative expression of the empA gene was very similar in all tested conditions. The NaCl concentration in the medium modulates the secretion of active EmpA protease in V. anguillarum at a post-transcriptional level. EmpA protease is one of the most important virulence factors in V. anguillarum. We demonstrated the influence of osmotic changes in the regulation of EmpA protease in the V. anguillarum 975/I strain. This finding has an important impact on the evaluation of factors determining the onset of disease in fish. © 2015 The Society for Applied Microbiology.

  10. Monitoring forest areas from continental to territorial levels using a sample of medium spatial resolution satellite imagery

    Science.gov (United States)

    Eva, Hugh; Carboni, Silvia; Achard, Frédéric; Stach, Nicolas; Durieux, Laurent; Faure, Jean-François; Mollicone, Danilo

    A global systematic sampling scheme has been developed by the UN FAO and the EC TREES project to estimate rates of deforestation at global or continental levels at intervals of 5 to 10 years. This global scheme can be intensified to produce results at the national level. In this paper, using surrogate observations, we compare the deforestation estimates derived from these two levels of sampling intensities (one, the global, for the Brazilian Amazon the other, national, for French Guiana) to estimates derived from the official inventories. We also report the precisions that are achieved due to sampling errors and, in the case of French Guiana, compare such precision with the official inventory precision. We extract nine sample data sets from the official wall-to-wall deforestation map derived from satellite interpretations produced for the Brazilian Amazon for the year 2002 to 2003. This global sampling scheme estimate gives 2.81 million ha of deforestation (mean from nine simulated replicates) with a standard error of 0.10 million ha. This compares with the full population estimate from the wall-to-wall interpretations of 2.73 million ha deforested, which is within one standard error of our sampling test estimate. The relative difference between the mean estimate from sampling approach and the full population estimate is 3.1%, and the standard error represents 4.0% of the full population estimate. This global sampling is then intensified to a territorial level with a case study over French Guiana to estimate deforestation between the years 1990 and 2006. For the historical reference period, 1990, Landsat-5 Thematic Mapper data were used. A coverage of SPOT-HRV imagery at 20 m × 20 m resolution acquired at the Cayenne receiving station in French Guiana was used for year 2006. Our estimates from the intensified global sampling scheme over French Guiana are compared with those produced by the national authority to report on deforestation rates under the Kyoto

  11. Inverse problem for a two-level medium with an inhomgeneously broadened transition in the field of a periodic wave

    International Nuclear Information System (INIS)

    Zabolotskii, A.A.

    1995-01-01

    The inverse problem is considered for a spectral problem, which is formally equivalent to a system of Bloch equations for an inhomogeneously broadened transition interacting with the electric field. Two cases are considered to demonstrate that, for any given frequency interval, one can determine the pulse of the shape which corresponds to the interaction with only this frequency interval. In the general case, the pulse shape is described by a nonlinear periodic wave. The first example is the resonance interaction of light with a gas of two-level atoms. The second example is interaction of a linearly polarized light with the molecular J-J transition, where J much-gt 1. In the latter case, the role of inhomogeneous broadening belongs to the frequency shift induced by the applied magnetic field. 10 refs

  12. Safety analysis of abnormal events for a model repository for low- and medium-level radioactive wastes

    International Nuclear Information System (INIS)

    Zurkinden, A.; Filleux, C.; Berger, E.; Schmid, G.; Schlaeppi, E.

    1984-01-01

    A safety assessment approach was developed which is consistent with the Swiss protection goals. The concept involves a scenario analysis to identify and catalogue those events and processes which could have an effect on the repository system and result in radiological consequences. The events and processes which are not considered in the normal evolution of the repository are then classified as realistic, hypothetical or irrelevant abnormal events. The evaluation of the radiological consequences for the realistic events involves a deterministic safety analysis. The hypothetical events may be assessed on the basis of probabilistic analysis methods. No further analysis is necessary for irrelevant events. The application of the safety assessment approach to a low- and intermediate-level waste model repository is demonstrated and the results from the classification of abnormal events are discussed. To further exemplify the methodology a safety analysis for a specific abnormal event is presented. (author)

  13. (SPWM) Voltage Source Inverter (VSI)

    African Journals Online (AJOL)

    The quest to achieve less-distorted dc-ac power conversion has resulted in the proliferation of many multilevel inverter configurations. This paper presents an experimental report of a simplified topology for single-phase, SPWM, three-level voltage source inverter wit R-L load. To keep the power circuit component count to a ...

  14. Voltage stability in low voltage microgrids in aspects of active and reactive power demand

    Directory of Open Access Journals (Sweden)

    Parol Mirosław

    2016-03-01

    Full Text Available Low voltage microgrids are autonomous subsystems, in which generation, storage and power and electrical energy consumption appear. In the paper the main attention has been paid to the voltage stability issue in low voltage microgrid for different variants of its operation. In the introduction a notion of microgrid has been presented, and also the issue of influence of active and reactive power balance on node voltage level has been described. Then description of voltage stability issue has been presented. The conditions of voltage stability and indicators used to determine voltage stability margin in the microgrid have been described. Description of the low voltage test microgrid, as well as research methodology along with definition of considered variants of its operation have been presented further. The results of exemplary calculations carried out for the daily changes in node load of the active and reactive power, i.e. the voltage and the voltage stability margin indexes in nodes have been presented. Furthermore, the changes of voltage stability margin indexes depending on the variant of the microgrid operation have been presented. Summary and formulation of conclusions related to the issue of voltage stability in microgrids have been included at the end of the paper.

  15. Improving transition voltage spectroscopy of molecular junctions

    DEFF Research Database (Denmark)

    Markussen, Troels; Chen, Jingzhe; Thygesen, Kristian Sommer

    2011-01-01

    Transition voltage spectroscopy (TVS) is a promising spectroscopic tool for molecular junctions. The principles in TVS is to find the minimum on a Fowler-Nordheim plot where ln(I/V2) is plotted against 1/V and relate the voltage at the minimum Vmin to the closest molecular level. Importantly, Vmin...

  16. Modeling and simulation of dynamic voltage restorer in power system

    International Nuclear Information System (INIS)

    Abdel Aziz, M.A.A.M.

    2012-01-01

    There are many loads subjected to several Power Quality Problems such as voltage sags/swells, unbalance, harmonics distortion, and short interruption. These loads encompass a wide range of equipment which are very sensitive to voltage disturbances. The Dynamic Voltage Restorer (DVR) has recently been introduced to protect sensitive loads from voltage sags and other voltage disturbances in addition to this, it mitigates current harmonics distortion. It is a series connected power electronic based device. It is considered as one of the most efficient and effective solutions. Its appeal includes smaller size and fast dynamic response to disturbances. This work describes a proposal of the DVR to improve power quality distribution (medium voltage) system. The control of the compensation voltage and harmonics cancellation in the DVR is based on Adaptive Noise Canceling (ANC) technique. Simulation results carried out by PSCAD/EMTDC to investigate the performance of the proposed method.

  17. Voltage stability evaluation of the Paraguayan system; Evaluacion de la estabilidad de tension del sistema paraguayo

    Energy Technology Data Exchange (ETDEWEB)

    Cardozo Sanchez, Freddy [Mirant Americas (United States); Fernandez Krekeler, Ubaldo [Administracion Nacional de Electricidad (ANDE), Asuncion (Paraguay)

    2001-07-01

    This document presents analyses of permanent status of the ANDE transmission system, seeking to evaluate the voltage stability and impact that would have possible reinforcements in 500 kV. The transmission under this new voltage level, besides to be a reinforcement to the system for satisfying the national demand, will permit the increase of energy exportation to Brazil, depending on the adopted reinforcement. The system current status and its evolution according to the planning of short and medium period are analysed. In the voltage stability evolution, static analysis techniques to draw the Q-V and P-V curves were used, as well as for determination of the system self-values and stability margins.

  18. High voltage engineering

    CERN Document Server

    Rizk, Farouk AM

    2014-01-01

    Inspired by a new revival of worldwide interest in extra-high-voltage (EHV) and ultra-high-voltage (UHV) transmission, High Voltage Engineering merges the latest research with the extensive experience of the best in the field to deliver a comprehensive treatment of electrical insulation systems for the next generation of utility engineers and electric power professionals. The book offers extensive coverage of the physical basis of high-voltage engineering, from insulation stress and strength to lightning attachment and protection and beyond. Presenting information critical to the design, selec

  19. Assessment of costs related to the implementation of management solutions on the long term for high and medium level long life radioactive wastes. ANDRA's proposition

    International Nuclear Information System (INIS)

    2014-10-01

    This huge document contains several volumes which propose detailed costing of the various parts of the Cigeo project after sketch studies (this project deals with the deep geological storage of high and medium level long life radioactive wastes). It notably states the various hypotheses regarding the inventory of radioactive wastes, the waste supply prediction, and works closure. This cost assessment takes the different project stages into account and a cost update. Various aspects are thus assessed, some related to investments (design studies, preliminary works, construction of the various installations, renewal of equipment during exploitation, installation dismantling and works closure, insurance, commissioning authority and engineering subcontracting), to exploitation (production and maintenance, support, activities related to safety, radiation protection and control of the environment, operating costs, utilities, storage containers, insurance), and to other expenses (tax, research and development, technological tests, control after closure)

  20. Development of a equipment to measure gas transport properties: Application to study candidate buffer mixtures for low-medium level waste repositories

    International Nuclear Information System (INIS)

    Martin, P. L.; Barcala, J. M.; Oller, J. C.

    2002-01-01

    This report describes the design, the construction and a testing of a system set-up for the measurement of gas transport, created at CIEMAT, and its application to study mixtures of candidate buffer materials for Low-Medium Level Waste Repertories. The measure of the gas flows is carried on by mass flow meters of several ranges, white the pressure of the applied within the sample is controlled. Two National l Instrument's acquisition system that permits the control and recording of the parameters. A specific application developed for this test, with National Instruments LabWIEW DSC, permits to mange the system. A client interface lets to follow the experiment course from a remote location through Internet. (Author) 21 refs

  1. Development of a Equipment to Measure Gas Transport Properties: Application to Study Mixtures of Candidates Buffer Materials for Low-Medium Level Waste Repositories

    Energy Technology Data Exchange (ETDEWEB)

    Martin, P.L.; Barcala, J.M.; Oller, J.C.

    2002-07-01

    This report describes the design, the construction and a testing of a system set-up for the measurement of gas transport, created at CIEMAT, and its application to study mixtures of candidate buffer materials for Low-Medium Level Waste Repertories. The measure of the gas flows is carried on by mass flow meters of several ranges, white the pressure of the applied within the sample is controlled. Two National l Instrument's acquisition system that permits the control and recording of the parameters. A specific application developed for this test, with National Instruments LabWIEW DSC, permits to mange the system. A client interface lets to follow the experiment course from a remote location through Internet. (Author) 21 refs.

  2. Quick-low-density parity check and dynamic threshold voltage optimization in 1X nm triple-level cell NAND flash memory with comprehensive analysis of endurance, retention-time, and temperature variation

    Science.gov (United States)

    Doi, Masafumi; Tokutomi, Tsukasa; Hachiya, Shogo; Kobayashi, Atsuro; Tanakamaru, Shuhei; Ning, Sheyang; Ogura Iwasaki, Tomoko; Takeuchi, Ken

    2016-08-01

    NAND flash memory’s reliability degrades with increasing endurance, retention-time and/or temperature. After a comprehensive evaluation of 1X nm triple-level cell (TLC) NAND flash, two highly reliable techniques are proposed. The first proposal, quick low-density parity check (Quick-LDPC), requires only one cell read in order to accurately estimate a bit-error rate (BER) that includes the effects of temperature, write and erase (W/E) cycles and retention-time. As a result, 83% read latency reduction is achieved compared to conventional AEP-LDPC. Also, W/E cycling is extended by 100% compared with conventional Bose-Chaudhuri-Hocquenghem (BCH) error-correcting code (ECC). The second proposal, dynamic threshold voltage optimization (DVO) has two parts, adaptive V Ref shift (AVS) and V TH space control (VSC). AVS reduces read error and latency by adaptively optimizing the reference voltage (V Ref) based on temperature, W/E cycles and retention-time. AVS stores the optimal V Ref’s in a table in order to enable one cell read. VSC further improves AVS by optimizing the voltage margins between V TH states. DVO reduces BER by 80%.

  3. Zero-Voltage Switching PWM Strategy Based Capacitor Current-Balancing Control for Half-Bridge Three-Level DC/DC Converter

    DEFF Research Database (Denmark)

    Liu, Dong; Deng, Fujin; Zhang, Qi

    2018-01-01

    The current imbalance among the two input capacitors is one of the important issues of the half-bridge threelevel (HBTL) DC/DC converter, which would affect system performance and reliability. In this paper, a zero-voltage switching (ZVS) pulse-wide modulation (PWM) strategy including two operation...... modes is proposed. Based on the proposed ZVS PWM strategy, a capacitor current-balancing control is proposed for the HBTL DC/DC converter, where the currents on the two input capacitors can be kept balanced by alternating the two operation modes of the proposed ZVS PWM strategy. Therefore, the proposed...... control strategy can improve the performance and reliability of the converter in the aspect of balancing the thermal stresses and lifetimes among the two input capacitors. Finally, simulation and experimental studies are conducted and results verify the proposed control strategy....

  4. Low voltage alpha EEG phenotype is associated with reduced amplitudes of alpha event-related oscillations, increased cortical phase synchrony, and a low level of response to alcohol.

    Science.gov (United States)

    Ehlers, Cindy L; Wills, Derek N; Phillips, Evelyn; Havstad, James

    2015-10-01

    Low voltage EEG (LVEEG) is a heritable phenotype that differs depending on ancestral heritage, yet its impact on brain networks and cognition remain relatively unexplored. In this study we assessed energy and task related phase locking of event-related oscillation (EROs), behavioral responses, measures of IQ and personality, and expected responses to alcohol in a large sample of individuals with LVEEG compared to those with higher voltage variants. Participants (n=762) were recruited from a Native American community and completed a diagnostic interview, the Quick Test, the Subjective High Assessment Scale Expectation Version (SHAS-E) and the Maudsley Personality Inventory. Clinical and spectral analyzed EEGs were collected for determination of the presence of a LVEEG variant. EROs were generated using a facial expression recognition task. Participants with LVEEG (n=451) were significantly more likely to be older, married and have higher degrees of Native American heritage but did not differ in gender, income or education. Individuals with LVEEG were also found to have decreased energy in their alpha EROs, increased phase locking between stimulus trials, and increased phase-locking between cortical brain areas. No significant differences in the cognitive tests, personality variables or alcohol dependence or anxiety diagnoses were found, however, individuals with LVEEG did report a larger number of drinks ever consumed in a 24-h period and a less intense expected response to alcohol. These data suggest that alpha power in the resting EEG is highly associated with energy and cortical connectivity measures generated by event-related stimuli, as well as potentially increased risk for alcohol use. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Low voltage alpha EEG phenotype is associated with reduced amplitudes of alpha event related oscillations, increased cortical phase synchrony, and a low level of response to alcohol

    Science.gov (United States)

    Ehlers, Cindy L.; Wills, Derek N.; Phillips, Evelyn; Havstad, James

    2015-01-01

    Low voltage EEG (LVEEG) is a heritable phenotype that differs depending on ancestral heritage, yet its impact on brain networks and cognition remain relatively unexplored. In this study we assessed energy and task related phase locking of event-related oscillation (EROs), behavioral responses, measures of IQ and personality, and expected responses to alcohol in a large sample of individuals with LVEEG compared to those with higher voltage variants. Participants (n=762) were recruited from a Native American community and completed a diagnostic interview, the Quick Test, the Subjective High Assessment Scale Expectation Version (SHAS-E) and the Maudsley Personality Inventory. Clinical and spectral analyzed EEGs were collected for determination of the presence of a LVEEG variant. EROs were generated using a facial expression recognition task. Participants with LVEEG (n=451) were significantly more likely to be older, married and have higher degrees of Native American heritage but did not differ in gender, income or education. Individuals with LVEEG were also found to have decreased energy in their alpha EROs, increased phase locking between stimulus trials, and increased phase-locking between cortical brain areas. No significant differences in the cognitive tests, personality variables or alcohol dependence or anxiety diagnoses were found, however, individuals with LVEEG did report a larger number of drinks ever consumed in a 24-hr period and a less intense expected response to alcohol. These data suggest that alpha power in the resting EEG is highly associated with energy and cortical connectivity measures generated by event-related stimuli, as well as potentially increased risk for alcohol use. PMID:26151497

  6. A control method for voltage balancing in modular multilevel converters

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2014-01-01

    The modular multilevel converter (MMC) is attractive for medium- or high-power applications because of the advantages of its high modularity, availability, and high power quality. The voltage balancing of the floating capacitors in the cascaded submodules of the MMC is a key issue. In this paper......, a voltage-balancing control method is proposed. This method uses the phase-shifted carrier-based pulsewidth modulation scheme to control high-frequency current components for capacitor voltage balancing in the MMC without measuring the arm currents. Simulations and experimental studies of the MMC were...... conducted, and the results confirm the effectiveness of the proposed capacitor voltage-balancing control method....

  7. Voltage Control Support and Coordination between Renewable Generation Plants in MV Distribution Systems

    DEFF Research Database (Denmark)

    Petersen, Lennart; Iov, Florin; Hansen, Anca Daniela

    2016-01-01

    This paper focusses on voltage control support and coordination between renewable generation plants in medium voltage distribution systems. An exemplary benchmark grid in Denmark, including a number of flexible ReGen plants providing voltage control functionality, is used as a base case. First...

  8. Distributed voltage control coordination between renewable generation plants in MV distribution grids

    DEFF Research Database (Denmark)

    Petersen, Lennart; Iov, Florin

    2017-01-01

    This study focuses on distributed voltage control coordination between renewable generation plants in medium-voltage distribution grids (DGs). A distributed offline coordination concept has been defined in a previous publication, leading to satisfactory voltage regulation in the DG. However, here...

  9. Highly-Efficient and Modular Medium-Voltage Converters

    Science.gov (United States)

    2015-09-28

    RESPONSIBLE PERSON Maryam Saeedifard 19b. TELEPHONE NUMBER (Include area code) 404 894 4834 Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std...evaluated by simula- tion studies. If the controller fails to converge, the arm inductive reactance will be resized . If the controller performance

  10. Mitigation of Voltage Dip and Voltage Flickering by Multilevel D-STATCOM

    Directory of Open Access Journals (Sweden)

    M. S. Ballal

    2012-01-01

    Full Text Available The basic power quality problems in the distribution network are voltage sag (dip, voltage flickering, and the service interruptions. STATCOM is a Flexible AC Transmission Systems (FACTS technology device which can independently control the flow of reactive power. This paper presents the simulation and analysis of a STATCOM for voltage dip and voltage flickering mitigation. Simulations are carried out in MATLAB/Simulink to validate the performance of the STATCOM. A comparison between the six-pulse inverter and the five-level diode-clamped inverter is carried out for the performance of 66/11 KV distribution system.

  11. Oligotrophy as a major driver of mercury bioaccumulation in medium-to high-trophic level consumers: A marine ecosystem-comparative study.

    Science.gov (United States)

    Chouvelon, Tiphaine; Cresson, Pierre; Bouchoucha, Marc; Brach-Papa, Christophe; Bustamante, Paco; Crochet, Sylvette; Marco-Miralles, Françoise; Thomas, Bastien; Knoery, Joël

    2018-02-01

    Mercury (Hg) is a global contaminant of environmental concern. Numerous factors influencing its bioaccumulation in marine organisms have already been described at both individual and species levels (e.g., size or age, habitat, trophic level). However, few studies have compared the trophic characteristics of ecosystems to explain underlying mechanisms of differences in Hg bioaccumulation and biomagnification among food webs and systems. The present study aimed at investigating the potential primary role of the trophic status of systems on Hg bioaccumulation and biomagnification in temperate marine food webs, as shown by their medium-to high-trophic level consumers. It used data from samples collected at the shelf-edge (i.e. offshore organisms) in two contrasted ecosystems: the Bay of Biscay in the North-East Atlantic Ocean and the Gulf of Lion in the North-West Mediterranean Sea. Seven species including crustaceans, sharks and teleost fish, previously analysed for their total mercury (T-Hg) concentrations and their stable carbon and nitrogen isotope compositions, were considered for a meta-analysis. In addition, methylated mercury forms (or methyl-mercury, Me-Hg) were analysed. Mediterranean organisms presented systematically lower sizes than Atlantic ones, and lower δ 13 C and δ 15 N values, the latter values especially highlighting the more oligotrophic character of Mediterranean waters. Mediterranean individuals also showed significantly higher T-Hg and Me-Hg concentrations. Conversely, Me-Hg/T-Hg ratios were higher than 85% for all species, and quite similar between systems. Finally, the biomagnification power of Hg was different between systems when considering T-Hg, but not when considering Me-Hg, and was not different between the Hg forms within a given system. Overall, the different parameters showed the crucial role of the low primary productivity and its effects rippling through the compared ecosystems in the higher Hg bioaccumulation seen in organisms

  12. High voltage DC power supply

    Science.gov (United States)

    Droege, Thomas F.

    1989-01-01

    A high voltage DC power supply having a first series resistor at the output for limiting current in the event of a short-circuited output, a second series resistor for sensing the magnitude of output current, and a voltage divider circuit for providing a source of feedback voltage for use in voltage regulation is disclosed. The voltage divider circuit is coupled to the second series resistor so as to compensate the feedback voltage for a voltage drop across the first series resistor. The power supply also includes a pulse-width modulated control circuit, having dual clock signals, which is responsive to both the feedback voltage and a command voltage, and also includes voltage and current measuring circuits responsive to the feedback voltage and the voltage developed across the second series resistor respectively.

  13. High voltage power supply

    Science.gov (United States)

    Ruitberg, A. P.; Young, K. M. (Inventor)

    1985-01-01

    A high voltage power supply is formed by three discrete circuits energized by a battery to provide a plurality of concurrent output signals floating at a high output voltage on the order of several tens of kilovolts. In the first two circuits, the regulator stages are pulse width modulated and include adjustable ressistances for varying the duty cycles of pulse trains provided to corresponding oscillator stages while the third regulator stage includes an adjustable resistance for varying the amplitude of a steady signal provided to a third oscillator stage. In the first circuit, the oscillator, formed by a constant current drive network and a tuned resonant network included a step up transformer, is coupled to a second step up transformer which, in turn, supplies an amplified sinusoidal signal to a parallel pair of complementary poled rectifying, voltage multiplier stages to generate the high output voltage.

  14. Ambient air levels of volatile organic compounds (VOC) and nitrogen dioxide (NO{sub 2}) in a medium size city in Northern Spain

    Energy Technology Data Exchange (ETDEWEB)

    Parra, M.A. [Laboratorio Integrado de Calidad Ambiental (LICA), Departamento de Quimica y Edafologia, Facultad de Ciencias, Universidad de Navarra. Irunlarrea 1, 31008, Pamplona, Navarra (Spain)], E-mail: mparravi@alumni.unav.es; Elustondo, D.; Bermejo, R.; Santamaria, J.M. [Laboratorio Integrado de Calidad Ambiental (LICA), Departamento de Quimica y Edafologia, Facultad de Ciencias, Universidad de Navarra. Irunlarrea 1, 31008, Pamplona, Navarra (Spain)

    2009-01-15

    Ambient concentrations of volatile organic compounds (VOC) and nitrogen dioxide (NO{sub 2}) were measured by means of passive sampling at 40 sampling points in a medium-size city in Northern Spain, from June 2006 to June 2007. VOC and NO{sub 2} samplers were analysed by thermal desorption followed by gas chromatography/mass-selective detector and by visible spectrophotometry, respectively. Mean concentrations of benzene, toluene, ethylbenzene, xylenes, propylbenzene, trimethylbenzenes, and NO{sub 2} were 2.84, 13.26, 2.15, 6.01, 0.59, 1.32 and 23.17 {mu}g m{sup -3} respectively, and found to be highly correlated. Their spatial distribution showed high differences in small distances and pointed to traffic as the main emission source of these compounds. The lowest levels of VOC and NO{sub 2} occurred during summer, owing to the increase in solar radiation and to lower traffic densities. Mean concentrations of benzene and NO{sub 2} exceeded the European limits at some of the monitored points.

  15. Medium-/long-term effects of a specific exercise protocol combined with patient education on spine mobility, chronic fatigue, pain, aerobic fitness and level of disability in fibromyalgia.

    Science.gov (United States)

    Giannotti, Erika; Koutsikos, Konstantinos; Pigatto, Maurizia; Rampudda, Maria Elisa; Doria, Andrea; Masiero, Stefano

    2014-01-01

    To propose a rehabilitation protocol able to produce immediate and long-term beneficial effects on level of disability and overall performance in ADLs. Forty-one FM patients were randomized to an exercise and educational-behavioral programme group (experimental group, EG = 21) or to a control group (CG = 20). Each subject was evaluated before, at the end (T1), and after 6 months (T6) from the conclusion of the rehabilitation treatment using the Fibromyalgia Impact Questionnaire (FIQ), the visual analogue scale (VAS), the Health Assessment Questionnaire (HAQ), the fatigue severity scale (FSS), the 6-minute walking test (6MWT), tender points count (TPC), and spinal active range of motion. The exercise protocol included 20 sessions consisting in self-awareness, stretching, strengthening, spine flexibility, and aerobic exercises, which patients were subsequently educated to perform at home. The two groups were comparable at baseline. At T1, the EG showed a positive trend in FIQ, VAS, HAQ, and FSS scales and significant improvement in 6MWT and in most spinal active range of motion measurements (P between 0.001 and 0.04). The positive results were maintained at the follow-up. The proposed programme was well tolerated and produced immediate and medium-term beneficial effects improving function and strain endurance. This trial is registered with DRKS00005071 on DRKS.

  16. Medium-/Long-Term Effects of a Specific Exercise Protocol Combined with Patient Education on Spine Mobility, Chronic Fatigue, Pain, Aerobic Fitness and Level of Disability in Fibromyalgia

    Directory of Open Access Journals (Sweden)

    Erika Giannotti

    2014-01-01

    Full Text Available Objective. To propose a rehabilitation protocol able to produce immediate and long-term beneficial effects on level of disability and overall performance in ADLs. Materials and Methods. Forty-one FM patients were randomized to an exercise and educational-behavioral programme group (experimental group, EG = 21 or to a control group (CG = 20. Each subject was evaluated before, at the end (T1, and after 6 months (T6 from the conclusion of the rehabilitation treatment using the Fibromyalgia Impact Questionnaire (FIQ, the visual analogue scale (VAS, the Health Assessment Questionnaire (HAQ, the fatigue severity scale (FSS, the 6-minute walking test (6MWT, tender points count (TPC, and spinal active range of motion. The exercise protocol included 20 sessions consisting in self-awareness, stretching, strengthening, spine flexibility, and aerobic exercises, which patients were subsequently educated to perform at home. Results. The two groups were comparable at baseline. At T1, the EG showed a positive trend in FIQ, VAS, HAQ, and FSS scales and significant improvement in 6MWT and in most spinal active range of motion measurements (P between 0.001 and 0.04. The positive results were maintained at the follow-up. Conclusion. The proposed programme was well tolerated and produced immediate and medium-term beneficial effects improving function and strain endurance. This trial is registered with DRKS00005071 on DRKS.

  17. Effect of low-level laser therapy on the release of interleukin-6 and basic fibroblast growth factor from cultured human skin fibroblasts in normal and high glucose mediums.

    Science.gov (United States)

    Esmaeelinejad, Mohammad; Bayat, Mohammad

    2013-12-01

    This study evaluated the effects of low-level laser therapy (LLLT) on human skin fibroblasts (HSFs) that have been cultured in high glucose concentration media. HSFs were cultured under physiological glucose condition medium, and then cultured in high glucose concentration medium (15 mM/L) for 1 or 2 weeks prior to LLLT. Experimental HSFs were irradiated with three energy densities (0.5, 1, and 2 J/cm(2)) once daily for three consecutive days. Release of interleukin-6 (IL-6) and basic fibroblast growth factor (bFGF) was evaluated using the enzyme-linked immunosorbent assay (ELISA) method. Statistical analysis showed three doses of 0.5 (p = 0.049), 1 (p = 0.027), and 2 J/cm(2) (p = 0.004) stimulated the release of IL-6 in HSFs cultured in high glucose concentration medium compared with that of non-irradiated HSFs that were cultured in the same medium. LLLT with 2 J/cm(2) induced the release of bFGF from HSFs cultured in high glucose concentration medium for 1 or 2 weeks (both p = 0.04). Our study showed that LLLT stimulated the release of IL-6 and bFGF from HSFs cultured in high glucose concentration medium. LLLT was more effective in releasing IL-6 and bFGF while HSFs which were cultured in physiologic glucose concentration medium during laser irradiation.

  18. High voltage pulse generator

    Science.gov (United States)

    Fasching, George E.

    1977-03-08

    An improved high-voltage pulse generator has been provided which is especially useful in ultrasonic testing of rock core samples. An N number of capacitors are charged in parallel to V volts and at the proper instance are coupled in series to produce a high-voltage pulse of N times V volts. Rapid switching of the capacitors from the paralleled charging configuration to the series discharging configuration is accomplished by using silicon-controlled rectifiers which are chain self-triggered following the initial triggering of a first one of the rectifiers connected between the first and second of the plurality of charging capacitors. A timing and triggering circuit is provided to properly synchronize triggering pulses to the first SCR at a time when the charging voltage is not being applied to the parallel-connected charging capacitors. Alternate circuits are provided for controlling the application of the charging voltage from a charging circuit to be applied to the parallel capacitors which provides a selection of at least two different intervals in which the charging voltage is turned "off" to allow the SCR's connecting the capacitors in series to turn "off" before recharging begins. The high-voltage pulse-generating circuit including the N capacitors and corresponding SCR's which connect the capacitors in series when triggered "on" further includes diodes and series-connected inductors between the parallel-connected charging capacitors which allow sufficiently fast charging of the capacitors for a high pulse repetition rate and yet allow considerable control of the decay time of the high-voltage pulses from the pulse-generating circuit.

  19. Development of a model of synchronous generator with a saturable transformer for the analysis of transient overvoltage in medium voltage systems; Desarrollo de un modelo de generador sincrono con transformador saturable para el analisis de sobrevoltajes transitorios en sistemas de mediana tension

    Energy Technology Data Exchange (ETDEWEB)

    Reyes Martinez, Oscar Alfonso

    2001-02-01

    In this work the problems of the transient overvoltage produced in the components that integrate the synchronous generators installed in industrial systems of medium voltage are approached. The development of a mathematical model in phase components for the synchronous generator is presented. The model includes a current saturation transformer, a system of static excitation and a scheme of grounding by low impedance through an energy cable. In the formulation the effect of the dampening windings is neglected since the interest is only to evaluate the effect of the initial transient overvoltage. Also, symmetry in the phases is considered and the saturation is neglected. The proposed mathematical model was evaluated through cases of simulation using real data of a typical industrial system. Also some tests were conducted in laboratories that, qualitatively, endorse the results obtained by simulation. Two real cases of electrical equipment fault by effect of transient overvoltage in industrial centers in Mexico were analyzed, with generators grounded through high impedance. [Spanish] En este trabajo se aborda la problematica de los sobrevoltajes transitorios producidos en los componentes que integran los generadores sincronos instalados en sistemas industriales de mediana tension. Se presenta el desarrollo de un modelo matematico en componentes de fase para el generador sincrono. El modelo incluye un transformador de corriente saturable, un sistema de excitacion estatica y un esquema de aterrizamiento por baja impedancia a traves de un cable de energia. En la formulacion se desprecia el efecto de los devanados amortiguadores debido a que solo interesa evaluar el efecto del sobrevoltaje transitorio inicial. Asi mismo, se considera simetria en las fases y se desprecia la saturacion. El modelo matematico propuesto fue evaluado a traves de casos de simulacion utilizando datos reales de un sistema industrial tipico. Tambien se realizaron algunas pruebas en laboratorios que

  20. Exploring Three-Phase Systems and Synchronous Motors: A Low-Voltage and Low-Cost Experiment at the Sophomore Level

    Science.gov (United States)

    Schubert, T. F., Jr.; Jacobitz, F. G.; Kim, E. M.

    2011-01-01

    In order to meet changing curricular and societal needs, a three-phase system and synchronous motor laboratory experience for sophomore-level students in a wide variety of engineering majors was designed, implemented, and assessed. The experiment is unusual in its early placement in the curriculum, and in that it focuses primarily on basic…

  1. Accelerator terminal voltage stability

    Science.gov (United States)

    Ferry, J. A.; Kolonko, J. J.; Phillips, S. H.; Lunstrum, S. J.

    1992-02-01

    Measurements reported at the 11th International Conference on Applications of Accelerators in Research and Industry [Schroeder et al., Nucl. Instr. and Meth. B56/B57 (1991) 1033] for a 1 MV single-ended Pelletron accelerator equipped with corona probe and tank liner voltage stabilizers have been extended by measuring the resonant yield of γ-rays from the 27Al(p, γ) 28Si reaction at 992 keV. Results show that terminal voltage stability is consistent with the earlier measurement of 31 V FWHM for ripple at 1 MV for periods of about one-half ( {1}/{2}) hour.

  2. Accelerator terminal voltage stability

    International Nuclear Information System (INIS)

    Ferry, J.A.; Kolonko, J.J.; Phillips, S.H.; Lunstrum, S.J.

    1992-01-01

    Measurements reported at the 11th International Conference on Applications of Accelerators in Research and Industry for a 1 MV single-ended Pelletron accelerator equipped with corona probe and tank liner voltage stabilizers have been extended by measuring the resonant yield of γ-rays from the 27 Al(p,γ) 28 Si reaction at 992 keV. Results show that terminal voltage stability is consistent with the earlier measurement of 31 V FWHM for ripple at 1 MV for periods of about one-half (1/2) hour. (orig.)

  3. Voltage Control in Wind Power Plants with Doubly Fed Generators

    DEFF Research Database (Denmark)

    Garcia, Jorge Martinez

    . To release the operation of the converters during steady-state disturbances, mechanically switched capacitors are installed in the wind power plant, which due to their characteristics, they are appropriate for permanent disturbances compensation. The mechanically switched capacitors are controlled to allow...... supplied by the doubly fed induction generator wind turbines is overcome by installing a reactive power compensator, i.e. a static compensator unit, which is coordinated with the plant control by a specific dispatcher. This dispatcher is set according to the result of the wind power plant load flow...... measured current at medium voltage, thus reducing the tap moving operations. Finally, due to the wind power plant reactive power is sized for maximum active power level, it is expected that a big amount of reactive power remains unused most of the time due to the wind power generation characteristics...

  4. Development of an industrial medium and a novel fed-batch strategy for high-level expression of recombinant β-mananase by Pichia pastoris.

    Science.gov (United States)

    Zheng, Jia; Zhao, Wei; Guo, Ning; Lin, Fulai; Tian, Jian; Wu, Lishuang; Zhou, Hongbo

    2012-08-01

    An industrial medium, Corn Steep Liquor Powder Dextrose (CSD medium) was developed for constitutive expression of recombinant β-mananase by Pichia pastoris. The β-mananase activity (513 U/mL) with CSD medium was 1.64- and 2.5-fold higher than with YPD and BSM in shaken flasks. The β-mananase productivity with CSD medium was 61.0 U/mL h, which was 1.7- and 2.5-fold higher than with YPD and BSM in a 5-L fermenter based on a novel fed-batch strategy combining the real-time exponential feed mode with the DO-stat feed mode. The β-mananase activity, dry cell weight and the recombinant enzyme reached up to 5132 U/mL, 110.0 g/L and 4.50 g/L after 50 h cultivation in a 50-L fermenter. The high efficient expression of recombinant β-mananase by P. pastoris indicated that CSD medium and the novel fed-batch strategy have great potential for the production of recombinant β-mananase in industrial fermentation. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Voltage scheduling for low power/energy

    Science.gov (United States)

    Manzak, Ali

    2001-07-01

    Power considerations have become an increasingly dominant factor in the design of both portable and desk-top systems. An effective way to reduce power consumption is to lower the supply voltage since voltage is quadratically related to power. This dissertation considers the problem of lowering the supply voltage at (i) the system level and at (ii) the behavioral level. At the system level, the voltage of the variable voltage processor is dynamically changed with the work load. Processors with limited sized buffers as well as those with very large buffers are considered. Given the task arrival times, deadline times, execution times, periods and switching activities, task scheduling algorithms that minimize energy or peak power are developed for the processors equipped with very large buffers. A relation between the operating voltages of the tasks for minimum energy/power is determined using the Lagrange multiplier method, and an iterative algorithm that utilizes this relation is developed. Experimental results show that the voltage assignment obtained by the proposed algorithm is very close (0.1% error) to that of the optimal energy assignment and the optimal peak power (1% error) assignment. Next, on-line and off-fine minimum energy task scheduling algorithms are developed for processors with limited sized buffers. These algorithms have polynomial time complexity and present optimal (off-line) and close-to-optimal (on-line) solutions. A procedure to calculate the minimum buffer size given information about the size of the task (maximum, minimum), execution time (best case, worst case) and deadlines is also presented. At the behavioral level, resources operating at multiple voltages are used to minimize power while maintaining the throughput. Such a scheme has the advantage of allowing modules on the critical paths to be assigned to the highest voltage levels (thus meeting the required timing constraints) while allowing modules on non-critical paths to be assigned

  6. Voltage Stabilizer Based on SPWM technique Using Microcontroller

    Directory of Open Access Journals (Sweden)

    K. N. Tarchanidis

    2013-01-01

    Full Text Available This paper presents an application of the well known SPWM technique on a voltage stabilizer, using a microcontroller. The stabilizer is AC/DC/AC type. So, the system rectifies the input AC voltage to a suitable DC level and the intelligent control of an embedded microcontroller regulates the pulse width of the output voltage in order to produce through a filter a perfect sinusoidal AC voltage. The control program on the microcontroller has the ability to change the FET transistor firing in order to compensate any input voltage variation. The applied software using the microcontroller’s interrupts managed to achieve concurrency on the running program.

  7. High voltage and electrical insulation engineering

    CERN Document Server

    Arora, Ravindra

    2011-01-01

    "The book is written for students as well as for teachers and researchers in the field of High Voltage and Insulation Engineering. It is based on the advance level courses conducted at TU Dresden, Germany and Indian Institute of Technology Kanpur, India. The book has a novel approach describing the fundamental concept of field dependent behavior of dielectrics subjected to high voltage. There is no other book in the field of high voltage engineering following this new approach in describing the behavior of dielectrics. The contents begin with the description of fundamental terminology in the subject of high voltage engineering. It is followed by the classification of electric fields and the techniques of field estimation. Performance of gaseous, liquid and solid dielectrics under different field conditions is described in the subsequent chapters. Separate chapters on vacuum as insulation and the lightning phenomenon are included"--

  8. Digital voltage discriminator

    International Nuclear Information System (INIS)

    Zhou Zhicheng

    1992-01-01

    A digital voltage discriminator is described, which is synthesized by digital comparator and ADC. The threshold is program controllable with high stability. Digital region of confusion is approximately equal to 1.5 LSB. This discriminator has a single channel analyzer function model with channel width of 1.5 LSB

  9. Geomagnetism and Induced Voltage

    Science.gov (United States)

    Abdul-Razzaq, W.; Biller, R. D.

    2010-01-01

    Introductory physics laboratories have seen an influx of "conceptual integrated science" over time in their classrooms with elements of other sciences such as chemistry, biology, Earth science, and astronomy. We describe a laboratory to introduce this development, as it attracts attention to the voltage induced in the human brain as it…

  10. Voltage Optimisation Technology for an Australian Abattoir—A Techno-Economic Evaluation

    Directory of Open Access Journals (Sweden)

    GM Shafiullah

    2017-11-01

    Full Text Available Optimising voltage levels to a controlled stable level at a facility can not only reduce the cost of energy but also enhance equipment performance, prolong equipment life, reduce maintenance costs and reduce greenhouse gas emissions. Voltage optimisation (VO technology has been widely used in a number of different industries locally and internationally, but not to a large extent within the red meat processing sector in Australia. To determine whether VO technology can be implemented, and whether it is technically and economically viable for red meat processing sites, this study investigated, through case study analyses, the potential effectiveness of VO technology in Australian abattoirs. Through an extensive literature survey, the study initially explored the need and considerations of deploying VO technologies at a typical red meat processing plant. To determine the advantages of using VO technology the study then performed site analyses to investigate power quality (PQ issues, such as voltage regulation, harmonics and power factor, at two typical medium-sized abattoirs, one in Western Australia and another in Queensland. Finally, an economic assessment of the use of VO in the red meat processing industry was undertaken to identify the potential electricity savings and payback periods. From the case study analyses, it is evident that power quality issues, such as under voltage, overvoltage, and harmonic distortion, can be reduced and significant energy savings can be achieved with the optimum selection of VO technology and voltage level. The outcomes of this study will enable engineering and operations staff to be better informed about the economic and technical benefits of (and possible issues with using VO technologies in an abattoir.

  11. High Voltage Charge Pump

    KAUST Repository

    Emira, Ahmed A.

    2014-10-09

    Various embodiments of a high voltage charge pump are described. One embodiment is a charge pump circuit that comprises a plurality of switching stages each including a clock input, a clock input inverse, a clock output, and a clock output inverse. The circuit further comprises a plurality of pumping capacitors, wherein one or more pumping capacitors are coupled to a corresponding switching stage. The circuit also comprises a maximum selection circuit coupled to a last switching stage among the plurality of switching stages, the maximum selection circuit configured to filter noise on the output clock and the output clock inverse of the last switching stage, the maximum selection circuit further configured to generate a DC output voltage based on the output clock and the output clock inverse of the last switching stage.

  12. A High-Power-Density Single-Phase Rectifier Based on Three-Level Neutral-Point Clamped Circuits

    Directory of Open Access Journals (Sweden)

    Tao Zhou

    2017-05-01

    Full Text Available A single-phase three-level converter is suitable for medium-power applications, with an interface voltage that is higher than that of a traditional two-level configuration. The three-level neutral-point clamped converter is adopted using four switches in each bridge arm, which, compared to a two-level rectifier, leads to less voltage stress, a lower switching frequency, and switching loss on switches. The transient current control strategy is designed to control the active power. The single-phase space vector pulse width modulation (SVPWM with a voltage balance strategy is designed to solve the neutral point voltage fluctuation problem and keep the dc-link voltage stable. A 1.3 kW high-power-density prototype based on SiC MOSFET was built and tested. The experimental results verified the high performance of steady-state and dynamic responses.

  13. A Transformer-less Partial Power Boost Converter for PV Applications Using a Three-Level Switching Cell

    Energy Technology Data Exchange (ETDEWEB)

    Agamy, Mohammed; Harfman-Todorovic, Maja; Elasser, Ahmed; Essakiappan, Somasundaram

    2013-03-01

    Photovoltaic architectures with distributed power electronics provide many advantages in terms of energy yield as well as system level optimization. As the power level of the solar farm increases it becomes more beneficial to increase the dc collection network voltage, which requires the use of power devices with higher voltage ratings, and thus making the design of efficient, low cost, distributed power converters more challenging. In this paper a simple partial power converter topology is proposed. The topology is implemented using a three-level switching cell, which allows the use of semiconductor devices with lower voltage rating; thus improving design and performance and reducing converter cost. This makes the converters suitable for use for medium to high power applications where dc-link voltages of 600V~1kV may be needed without the need for high voltage devices. Converter operation and experimental results are presented for two partial power circuit variants using three-level switching cells.

  14. High voltage generator

    Science.gov (United States)

    Schwemin, A. J.

    1959-03-17

    A generator for producing relatively large currents at high voltages is described. In general, the invention comprises a plurality of capacitors connected in series by a plurality of switches alternately disposed with the capacitors. The above-noted circuit is mounted for movement with respect to contact members and switch closure means so that a load device and power supply are connected across successive numbers of capacitors, while the other capacitors are successively charged with the same power supply.

  15. High Voltage Seismic Generator

    Science.gov (United States)

    Bogacz, Adrian; Pala, Damian; Knafel, Marcin

    2015-04-01

    This contribution describes the preliminary result of annual cooperation of three student research groups from AGH UST in Krakow, Poland. The aim of this cooperation was to develop and construct a high voltage seismic wave generator. Constructed device uses a high-energy electrical discharge to generate seismic wave in ground. This type of device can be applied in several different methods of seismic measurement, but because of its limited power it is mainly dedicated for engineering geophysics. The source operates on a basic physical principles. The energy is stored in capacitor bank, which is charged by two stage low to high voltage converter. Stored energy is then released in very short time through high voltage thyristor in spark gap. The whole appliance is powered from li-ion battery and controlled by ATmega microcontroller. It is possible to construct larger and more powerful device. In this contribution the structure of device with technical specifications is resented. As a part of the investigation the prototype was built and series of experiments conducted. System parameter was measured, on this basis specification of elements for the final device were chosen. First stage of the project was successful. It was possible to efficiently generate seismic waves with constructed device. Then the field test was conducted. Spark gap wasplaced in shallowborehole(0.5 m) filled with salt water. Geophones were placed on the ground in straight line. The comparison of signal registered with hammer source and sparker source was made. The results of the test measurements are presented and discussed. Analysis of the collected data shows that characteristic of generated seismic signal is very promising, thus confirms possibility of practical application of the new high voltage generator. The biggest advantage of presented device after signal characteristics is its size which is 0.5 x 0.25 x 0.2 m and weight approximately 7 kg. This features with small li-ion battery makes

  16. High voltage pulse conditioning

    International Nuclear Information System (INIS)

    Springfield, R.M.; Wheat, R.M.

    1990-01-01

    This patent describes an apparatus for conditioning high voltage pulses from particle accelerators in order to shorten the rise times of the pulses. Flashover switches in the cathode stalk of the transmission line hold off conduction for a determinable period of time, reflecting the early portion of the pulses. Diodes upstream of the switches divert energy into the magnetic and electrostatic storage of the capacitance and inductance inherent to the transmission line until the switches close

  17. High voltage electrical injuries

    International Nuclear Information System (INIS)

    Janjua, S.A.

    2002-01-01

    Objective: To highlight the devastating nature and consequences of high voltage electrical injuries and to stress the need for its prevention. Design: It was a retrospective study. Place and duration of study: The study was conducted at Army Burn Centre, Combined Military Hospital Kharian Cantonment, between January 1,1998 to December 31, 2000. Subjects and Methods: All the patients reporting to Army Burn Centre with high voltage electrical injuries were included in the study. The epidemiology of these injuries were studied along with the pattern of their management and outcome in terms of mortality and morbidity. Results: Of all the patients admitted to the Army Burn Center, 5.94% were affected with electrical injuries. They were predominantly males in a ratio of 9.75:1 and mostly in the 3rd and 4th decades of their lives. Seventy percent of these injuries were injuries were work-related and 75% had associated surface burns. There was significant mortality rate of 18.6% and a limb amputation rate of 80% along with professional disability rate of 91% rendering it a highly morbid condition. Conclusion: This study stresses the necessity to educate the general public with regard to the devastating nature of high voltage electrical injury and highlight the importance of prevention. (author)

  18. Application of Load Compensation in Voltage Controllers of Large Generators in the Polish Power Grid

    Directory of Open Access Journals (Sweden)

    Bogdan Sobczak

    2014-03-01

    Full Text Available The Automatic Voltage Regulator normally controls the generator stator terminal voltage. Load compensation is used to control the voltage which is representative of the voltage at a point either within or external to the generator. In the Polish Power Grid (PPG compensation is ready to use in every AVR of a large generator, but it is utilized only in the case of generators operating at the same medium voltage buses. It is similar as in most European Power Grids. The compensator regulating the voltage at a point beyond the machine terminals has significant advantages in comparison to the slower secondary Voltage and Reactive Power Control System (ARNE1. The compensation stiffens the EHV grid, which leads to improved voltage quality in the distribution grid. This effect may be particularly important in the context of the dynamic development of wind and solar energy.

  19. Wide-range voltage modulation

    International Nuclear Information System (INIS)

    Rust, K.R.; Wilson, J.M.

    1992-06-01

    The Superconducting Super Collider's Medium Energy Booster Abort (MEBA) kicker modulator will supply a current pulse to the abort magnets which deflect the proton beam from the MEB ring into a designated beam stop. The abort kicker will be used extensively during testing of the Low Energy Booster (LEB) and the MEB rings. When the Collider is in full operation, the MEBA kicker modulator will abort the MEB beam in the event of a malfunction during the filling process. The modulator must generate a 14-μs wide pulse with a rise time of less than 1 μs, including the delay and jitter times. It must also be able to deliver a current pulse to the magnet proportional to the beam energy at any time during ramp-up of the accelerator. Tracking the beam energy, which increases from 12 GeV at injection to 200 GeV at extraction, requires the modulator to operate over a wide range of voltages (4 kV to 80 kV). A vacuum spark gap and a thyratron have been chosen for test and evaluation as candidate switches for the abort modulator. Modulator design, switching time delay, jitter and pre-fire data are presented

  20. Mitigation of Voltage Sags in CIGRE Low Voltage Distribution Network

    DEFF Research Database (Denmark)

    Mustafa, Ghullam; Bak-Jensen, Birgitte; Mahat, Pukar

    2013-01-01

    Any problem in voltage in a power network is undesirable as it aggravates the quality of the power. Power electronic devices such as Voltage Source Converter (VSC) based Static Synchronous Compensator (STATCOM), Dynamic Voltage Restorer (DVR) etc. are commonly used for the mitigation of voltage p....... The compensation of voltage sags in the different parts of CIGRE distribution network is done by using the four STATCOM compensators already existing in the test grid. The simulations are carried out in DIgSILENT power factory software version 15.0....

  1. Suppressing voltage transients in high voltage power supplies

    International Nuclear Information System (INIS)

    Lickel, K.F.; Stonebank, R.

    1979-01-01

    A high voltage power supply for an X-ray tubes includes voltage adjusting means, a high voltage transformer, switch means connected to make and interrupt the primary current of the transformer, and over-voltage suppression means to suppress the voltage transient produced when the current is switched on. In order to reduce the power losses in the suppression means, an impedance is connected in the transformer primary circuit on operation of the switch means and is subsequently short-circuited by a switch controlled by a timer after a period which is automatically adjusted to the duration of the transient overvoltage. (U.K.)

  2. Charge-pump voltage converter

    Science.gov (United States)

    Brainard, John P [Albuquerque, NM; Christenson, Todd R [Albuquerque, NM

    2009-11-03

    A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

  3. Quadratic sinusoidal analysis of voltage clamped neurons.

    Science.gov (United States)

    Magnani, Christophe; Moore, Lee E

    2011-11-01

    Nonlinear biophysical properties of individual neurons are known to play a major role in the nervous system, especially those active at subthreshold membrane potentials that integrate synaptic inputs during action potential initiation. Previous electrophysiological studies have made use of a piecewise linear characterization of voltage clamped neurons, which consists of a sequence of linear admittances computed at different voltage levels. In this paper, a fundamentally new theory is developed in two stages. First, analytical equations are derived for a multi-sinusoidal voltage clamp of a Hodgkin-Huxley type model to reveal the quadratic response at the ionic channel level. Second, the resulting behavior is generalized to a novel Hermitian neural operator, which uses an algebraic formulation capturing the entire quadratic behavior of a voltage clamped neuron. In addition, this operator can also be used for a nonlinear identification analysis directly applicable to experimental measurements. In this case, a Hermitian matrix of interactions is built with paired frequency probing measurements performed at specific harmonic and interactive output frequencies. More importantly, eigenanalysis of the neural operator provides a concise signature of the voltage dependent conductances determined by their particular distribution on the dendritic and somatic membrane regions of neurons. Finally, the theory is concretely illustrated by an analysis of an experimentally measured vestibular neuron, providing a remarkably compact description of the quadratic responses involved in the nonlinear processing underlying the control of eye position during head rotation, namely the neural integrator.

  4. A Refined Self-Tuning Filter-Based Instantaneous Power Theory Algorithm for Indirect Current Controlled Three-Level Inverter-Based Shunt Active Power Filters under Non-sinusoidal Source Voltage Conditions

    Directory of Open Access Journals (Sweden)

    Yap Hoon

    2017-02-01

    Full Text Available In this paper, a refined reference current generation algorithm based on instantaneous power (pq theory is proposed, for operation of an indirect current controlled (ICC three-level neutral-point diode clamped (NPC inverter-based shunt active power filter (SAPF under non-sinusoidal source voltage conditions. SAPF is recognized as one of the most effective solutions to current harmonics due to its flexibility in dealing with various power system conditions. As for its controller, pq theory has widely been applied to generate the desired reference current due to its simple implementation features. However, the conventional dependency on self-tuning filter (STF in generating reference current has significantly limited mitigation performance of SAPF. Besides, the conventional STF-based pq theory algorithm is still considered to possess needless features which increase computational complexity. Furthermore, the conventional algorithm is mostly designed to suit operation of direct current controlled (DCC SAPF which is incapable of handling switching ripples problems, thereby leading to inefficient mitigation performance. Therefore, three main improvements are performed which include replacement of STF with mathematical-based fundamental real power identifier, removal of redundant features, and generation of sinusoidal reference current. To validate effectiveness and feasibility of the proposed algorithm, simulation work in MATLAB-Simulink and laboratory test utilizing a TMS320F28335 digital signal processor (DSP are performed. Both simulation and experimental findings demonstrate superiority of the proposed algorithm over the conventional algorithm.

  5. A compact 100 kV high voltage glycol capacitor.

    Science.gov (United States)

    Wang, Langning; Liu, Jinliang; Feng, Jiahuai

    2015-01-01

    A high voltage capacitor is described in this paper. The capacitor uses glycerol as energy storage medium, has a large capacitance close to 1 nF, can hold off voltages of up to 100 kV for μs charging time. Allowing for low inductance, the capacitor electrode is designed as coaxial structure, which is different from the common structure of the ceramic capacitor. With a steady capacitance at different frequencies and a high hold-off voltage of up to 100 kV, the glycol capacitor design provides a potential substitute for the ceramic capacitors in pulse-forming network modulator to generate high voltage pulses with a width longer than 100 ns.

  6. Heat-pump performance: voltage dip/sag, under-voltage and over-voltage

    Directory of Open Access Journals (Sweden)

    William J.B. Heffernan

    2014-12-01

    Full Text Available Reverse cycle air-source heat-pumps are an increasingly significant load in New Zealand and in many other countries. This has raised concern over the impact wide-spread use of heat-pumps may have on the grid. The characteristics of the loads connected to the power system are changing because of heat-pumps. Their performance during under-voltage events such as voltage dips has the potential to compound the event and possibly cause voltage collapse. In this study, results from testing six heat-pumps are presented to assess their performance at various voltages and hence their impact on voltage stability.

  7. Evaluation of the Voltage Support Strategies for the Low Voltage Grid Connected PV

    DEFF Research Database (Denmark)

    Demirok, Erhan; Sera, Dezso; Teodorescu, Remus

    2010-01-01

    Admissible range of grid voltage is one of the strictest constraints for the penetration of distributed photovoltaic (PV) generators especially connection to low voltage (LV) public networks. Voltage limits are usually fulfilled either by network reinforcements or limiting of power injections from...... PVs. In order to increase PV penetration level further, new voltage support control functions for individual inverters are required. This paper investigates distributed reactive power regulation and active power curtailment strategies regarding the development of PV connection capacity by evaluation...... of reactive power efforts and requirement of minimum active power curtailment. Furthermore, a small scale experimental setup is built to reflect real grid interaction in the laboratory by achieving critical types of grid (weak and sufficiently stiff)....

  8. Stray voltage and robotic milking of dairy cows

    Energy Technology Data Exchange (ETDEWEB)

    Rodenburg, J.; Lang, B. [Ontario Ministry of Agriculture (Canada)

    2009-12-15

    Stray voltage in livestock agriculture is the difference in voltage potential measured between two surfaces that may be contacted simultaneously by an animal. The reactions of animals to mild electric shocks caused by stray voltage have been reported to include behavioural changes, changes in milking characteristics of dairy cows and changes in production performance. It can make cows more reluctant to enter the farm dairy and can induce more frequent dunging and urination in the holding yards or during milking. Milk production may be reduced if avoidance behaviours are severe. This factsheet outlines appropriate testing of a robot site for stray voltage. Correction and prevention options available to reduce or eliminate stray voltage in robotic milking systems, i.e. equipotential plane or slatted floors, are discussed along with advantages and disadvantages of each. The most appropriate solution may depend on the voltage level found, the utility's policies and whether it is new construction or renovation.

  9. Quantifying transition voltage spectroscopy of molecular junctions: Ab initio calculations

    DEFF Research Database (Denmark)

    Chen, Jingzhe; Markussen, Troels; Thygesen, Kristian Sommer

    2010-01-01

    Transition voltage spectroscopy (TVS) has recently been introduced as a spectroscopic tool for molecular junctions where it offers the possibility to probe molecular level energies at relatively low bias voltages. In this work we perform extensive ab initio calculations of the nonlinear current...

  10. Design and control of single-phase dynamic voltage restorer

    Indian Academy of Sciences (India)

    Amit Meena

    The integration of series and shunt converter makes the .... integrating the output of PI controller and constant angular frequency. ..... including under-voltage lockouts, over-current shutdown and fault reporting. The built-in driver circuit translates the incoming logic-level gate inputs to the high-voltage,. 0.32. 0.34. 0.36. 0.38.

  11. A Modular Cascaded Multilevel Inverter Based Shunt Hybrid Active Power Filter for Selective Harmonic and Reactive Power Compensation Under Distorted/Unbalanced Grid Voltage Conditions

    Directory of Open Access Journals (Sweden)

    T. Demirdelen

    2016-10-01

    Full Text Available In recent years, shunt hybrid active power filters are being increasingly considered as a viable alternative to both passive filters and active power filters for compensating harmonics. In literature, their applications are restricted to balanced systems and low voltage applications and therefore not for industrial applications. This paper investigates the performance of a modular cascaded multilevel inverter based Shunt Hybrid Active Power Filter (SHAPF for reactive power compensation and selective harmonics elimination under distorted/unbalanced grid voltage conditions in medium voltage levels. In the proposed control method, reactive power compensation is achieved successfully with a perceptible amount and the performance results of harmonic compensation are satisfactory. Theoretical analysis and simulation results are obtained from an actual industrial network model in PSCAD. The simulation results are presented for a proposed system in order to demonstrate that the harmonic compensation performance meets the IEEE-519 standard.

  12. Voltage Dependence of Supercapacitor Capacitance

    Directory of Open Access Journals (Sweden)

    Szewczyk Arkadiusz

    2016-09-01

    Full Text Available Electronic Double-Layer Capacitors (EDLC, called Supercapacitors (SC, are electronic devices that are capable to store a relatively high amount of energy in a small volume comparing to other types of capacitors. They are composed of an activated carbon layer and electrolyte solution. The charge is stored on electrodes, forming the Helmholtz layer, and in electrolyte. The capacitance of supercapacitor is voltage- dependent. We propose an experimental method, based on monitoring of charging and discharging a supercapacitor, which enables to evaluate the charge in an SC structure as well as the Capacitance-Voltage (C-V dependence. The measurement setup, method and experimental results of charging/discharging commercially available supercapacitors in various voltage and current conditions are presented. The total charge stored in an SC structure is proportional to the square of voltage at SC electrodes while the charge on electrodes increases linearly with the voltage on SC electrodes. The Helmholtz capacitance increases linearly with the voltage bias while a sublinear increase of total capacitance was found. The voltage on SC increases after the discharge of electrodes due to diffusion of charges from the electrolyte to the electrodes. We have found that the recovery voltage value is linearly proportional to the initial bias voltage value.

  13. Pulse-voltage fast generator

    International Nuclear Information System (INIS)

    Valeev, R.I.; Nikiforov, M.G.; Kharchenko, A.F.

    1988-01-01

    The design is described and the test results of a four-channel pulse-voltage generator with maximum output voltage 200 kV are presented. The measurement results of generator triggering time depending on the value and polarity of the triggering voltage pulse for different triggering circuits are presented. The tests have shown stable triggering of all four channels of the generator in the range up to 40 % from selfbreakdown voltage. The generator triggering delay in the given range is <25 ns, asynchronism in channel triggering is <±1 ns

  14. Capacitor storage voltage stabilization device

    International Nuclear Information System (INIS)

    Logvin, V.V.; Gusev, E.V.

    1987-01-01

    An electric circuit of a device designed for charging and stabilizing a capacitor storage is described. A phase-pulse method for thyristor control in the power transformer first circuit is used. In the process of storage charging the triggering angle of thyristors linearly grows, that excludes the necessity of application of current-limiting elements in the charging circuit. The averaged charging voltage of the storage linearly dependce on charging time. Charging is realized by a series of short-time current pulses. Output voltage is controlled within 10...95% limits of the rated value. Voltage instability is ≤0.5% at power supply voltage variation of ±10%

  15. Temporary over voltages in the high voltage networks

    International Nuclear Information System (INIS)

    Vukelja, Petar; Naumov, Radomir; Mrvic, Jovan; Minovski, Risto

    2001-01-01

    The paper treats the temporary over voltages that may arise in the high voltage networks as a result of: ground faults, loss of load, loss of one or two phases and switching operation. Based on the analysis, the measures for their limitation are proposed. (Original)

  16. Hierarchical Control Scheme for Voltage Unbalance Compensation in Islanded Microgrids

    DEFF Research Database (Denmark)

    Savaghebi, Mehdi; Guerrero, Josep M.; Jalilian, Alireza

    2011-01-01

    The concept of microgrid hierarchical control is presented, recently. In this paper, a hierarchical scheme which includes primary and secondary control levels is proposed for islanded microgrids. The primary control level consists of DG local controllers. Local controller of each DG comprises...... active and reactive power controllers, virtual impedance loop and voltage and current controllers. The secondary level is designed to compensate the voltage unbalance at the load bus (LB) of the islanded microgrid. Also, restoration of LB voltage amplitude and microgrid frequency to the rated values...

  17. Medium-spin levels and a 360 ns Isup(π)=19-/2 isomer in the N=80 nucleus 137La

    International Nuclear Information System (INIS)

    Kortelahti, M.; Pakkanen, A.; Piiparinen, M.; Komppa, T.; Komu, R.

    1981-03-01

    The level structure of 137 La has been studied using the 138 Ba(p,2n) reaction and methods of in-beam γ-ray and conversion-electron spectroscopy. The 137 La level scheme has been established with 21 new levels with spins up to (19/2) - . A 360 ns (19/2) - isomer at 1870 keV has been identified and a (πgsub(7/2)(νhsub(11/2)sup(-1)dsub(3/2)sup(-1)sub(7 - ))sub(19/2) - configuration is suggested for it. The level ordering of the πhsub(11/2)x2 + multiplet has been discussed on the basis of the triaxial rotor-plus-particle model which suggests a slightly oblate triaxial shape to the 137 La nucleus. (author)

  18. 1014 enforcement of entrepreneurship in the public and private schools: high and medium level career in the city of Villavicencio, Meta

    Directory of Open Access Journals (Sweden)

    Dora Navarro-Quintero

    2012-12-01

    development and growth of nations. The exploratory and descriptive research design appropriate experimental is-not where the population is composed of 55 public and private institutions of secondary and intermediate vocational level in the city of Villavicencio - Meta

  19. Fundamental studies on the switching in liquid nitrogen environment using vacuum switches for application in future high-temperature superconducting medium-voltage power grids; Grundsatzuntersuchungen zum Schalten in Fluessigstickstoff-Umgebung mit Vakuumschaltern zur Anwendung in zukuenftigen Hochtemperatur-Supraleitungs-Mittelspannungsnetzen

    Energy Technology Data Exchange (ETDEWEB)

    Golde, Karsten

    2016-06-24

    By means of superconducting equipment it is possible to reduce the transmission losses in distribution networks while increasing the transmission capacity. As a result even saving a superimposed voltage level would be possible, which can put higher investment costs compared to conventional equipment into perspective. For operation of superconducting systems it is necessary to integrate all equipment in the cooling circuit. This also includes switchgears. Due to cooling with liquid nitrogen, however, only vacuum switching technology comes into question. Thus, the suitability of vacuum switches is investigated in this work. For this purpose the mechanics of the interrupters is considered first. Material investigations and switching experiments at ambient temperature and in liquid nitrogen supply information on potential issues. For this purpose, a special pneumatic construction is designed, which allows tens of thousands of switching cycles. Furthermore, the electrical resistance of the interrupters is considered. Since the contact system consists almost exclusively of copper, a remaining residual resistance and appropriate thermal losses must be considered. Since they have to be cooled back, an appropriate evaluation is given taking environmental parameters into account. The dielectric strength of vacuum interrupters is considered both at ambient temperature as well as directly in liquid nitrogen. For this purpose different contact distances are set at different interrupter types. A distinction is made between internal and external dielectric strength. Conditioning and deconditioning effects are minimized by an appropriate choice of the test circuit. The current chopping and resulting overvoltages are considered to be one of the few drawbacks of vacuum switching technology. Using a practical test circuit the height of chopping current is determined and compared for different temperatures. Due to strong scattering the evaluation is done using statistical methods. At

  20. BEHAVIOUR OF BACKFILL MATERIALS FOR ELECTRICAL GROUNDING SYSTEMS UNDER HIGH VOLTAGE CONDITIONS

    Directory of Open Access Journals (Sweden)

    S. C. LIM

    2015-06-01

    Full Text Available Backfill materials like Bentonite and cement are effective in lowering grounding resistance of electrodes for a considerable period. During lightning, switching impulses and earth fault occurrences in medium and high voltage networks, the grounding system needs to handle extremely high currents either for a short duration or prolonged period respectively. This paper investigates the behaviour of bentonite, cement and sand under impulse and alternating high voltage (50Hz conditions. Fulguritic-formation was observed in all materials under alternating high voltage. The findings reveal that performance of grounding systems under high voltage conditions may significantly change from the outcomes anticipated at design stage.

  1. Phase-angle jump during voltage dips in wind power installations

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Lazaro, E.; Canas, M.; Pujante, A.J. [Universidad de Castilla-La Mancha, Albacete (Spain). Renewable Energy Research Inst. and Dept. of Electrical, Electronic and Control Engineering; Fuentes, J.A.; Molina-Garcia, A. [Universidad Politecnica de Cartagena (Spain). Dept. of Electrical Engineering

    2008-07-01

    A voltage dip is a disturbance in the power system that consists in a sudden reduction of voltage level and a recovery in a short period of time, the magnitude and angle of the voltage phasors can be affected by this disturbance. The variation between the pre-fault voltage phasor angle and dip voltage phasor angle is called phase-angle jump. In this paper, it is carried out a study of the characteristics of real voltage dips. The study highlights the phase-angle jumps that appear on voltage dips, analyzing the influence of the voltage dip type, depth or length. Voltage dips have been acquired with power quality analyzers with a 10 MHz sample rate in a Spanish wind farm for 18 months. (orig.)

  2. High voltage pulse generator. [Patent application

    Science.gov (United States)

    Fasching, G.E.

    1975-06-12

    An improved high-voltage pulse generator is described which is especially useful in ultrasonic testing of rock core samples. An N number of capacitors are charged in parallel to V volts and at the proper instance are coupled in series to produce a high-voltage pulse of N times V volts. Rapid switching of the capacitors from the paralleled charging configuration to the series discharging configuration is accomplished by using silicon-controlled rectifiers which are chain self-triggered following the initial triggering of the first rectifier connected between the first and second capacitors. A timing and triggering circuit is provided to properly synchronize triggering pulses to the first SCR at a time when the charging voltage is not being applied to the parallel-connected charging capacitors. The output voltage can be readily increased by adding additional charging networks. The circuit allows the peak level of the output to be easily varied over a wide range by using a variable autotransformer in the charging circuit.

  3. The Design and Characterization of a Prototype Wideband Voltage Sensor Based on a Resistive Divider.

    Science.gov (United States)

    Garnacho, Fernando; Khamlichi, Abderrahim; Rovira, Jorge

    2017-11-17

    The most important advantage of voltage dividers over traditional voltage transformers is that voltage dividers do not have an iron core with non-linear hysteresis characteristics. The voltage dividers have a linear behavior with respect to over-voltages and a flat frequency response larger frequency range. The weak point of a voltage divider is the influence of external high-voltage (HV) and earth parts in its vicinity. Electrical fields arising from high voltages in neighboring phases and from ground conductors and structures are one of their main sources for systematic measurement errors. This paper describes a shielding voltage divider for a 24 kV medium voltage network insulated in SF6 composed of two resistive-capacitive dividers, one integrated within the other, achieving a flat frequency response up to 10 kHz for ratio error and up to 5 kHz for phase displacement error. The metal shielding improves its immunity against electric and magnetic fields. The characterization performed on the built-in voltage sensor shows an accuracy class of 0.2 for a frequency range from 20 Hz to 5 kHz and a class of 0.5 for 1 Hz up to 20 Hz. A low temperature effect is also achieved for operation conditions of MV power grids.

  4. APPLICATION OF INCREASED BREAKDOWN VOLTAGE SWITCH TO CLASS-E AMPLIFIER

    Directory of Open Access Journals (Sweden)

    Mustafa SÖNMEZ

    1998-02-01

    Full Text Available Class-E amplifier consist of a switching device (BJT or FET and a rezonant circuit. The power of amplifier depends on current and supply voltage of the transistor. The breakdown voltage of the transistor is increased to the maximum level in order to increase the power of the amplifier. Because of increasing the current increases the reverse induction, the reverse voltage creates a problem for the transistor. In this work, the increased breakdown voltage transistor Configuration is applied to class-E power amplifiers. Therefore, the reverse voltage problem is solved and supply voltage.

  5. Mitigation of Unbalanced Voltage Sags and Voltage Unbalance in CIGRE Low Voltage Distribution Network

    DEFF Research Database (Denmark)

    Mustafa, Ghullam; Bak-Jensen, Birgitte; Mahat, Pukar

    2013-01-01

    to unbalanced faults. The compensation of unbalanced voltage sags and voltage unbalance in the CIGRE distribution network is done by using the four STATCOM compensators already existing in the test grid. The simulations are carried out in DIgSILENT power factory software version 15.0....

  6. Coordinated Voltage Control of Distributed PV Inverters for Voltage Regulation in Low Voltage Distribution Networks

    DEFF Research Database (Denmark)

    Nainar, Karthikeyan; Pokhrel, Basanta Raj; Pillai, Jayakrishnan Radhakrishna

    2017-01-01

    on measured local voltages. The advantage of the proposed method is that the calculated reactive power and active power droop settings enable fair contribution of the PV inverters at each node to the voltage regulation. Simulation studies are conducted using DigSilent Power factory software on a simplified...

  7. Mitigation of Voltage Swells by Static Series Compensator

    DEFF Research Database (Denmark)

    Awad, Hilmy; Blaabjerg, Frede

    2004-01-01

    is lower than a predetermined voltage level, the active power is employed to charge the ESC to this voltage level; 2) otherwise, the overvoltage protection of the SSC must operate. This paper also applies an overvoltage protection scheme based on a combination of a dc resistor with a chopper and the valves...... of the SSC. The design of the dc resistor is discussed. A 10 kV SSC experimental setup is exploited to carry out experiments in the case of balanced and unbalanced voltage swells at the grid side....

  8. Habitual levels of higher, but not medium or low, impact physical activity are positively related to lower limb bone strength in older women: findings from a population-based study using accelerometers to classify impact magnitude.

    Science.gov (United States)

    Hannam, K; Deere, K C; Hartley, A; Al-Sari, U A; Clark, E M; Fraser, W D; Tobias, J H

    2017-10-01

    associations were not seen for low or medium impacts. Despite their rarity, habitual levels of higher impacts were positively associated with lower limb bone size and strength, whereas equivalent relationships were not seen for low or medium impacts.

  9. PV source based high voltage gain current fed converter

    Science.gov (United States)

    Saha, Soumya; Poddar, Sahityika; Chimonyo, Kudzai B.; Arunkumar, G.; Elangovan, D.

    2017-11-01

    This work involves designing and simulation of a PV source based high voltage gain, current fed converter. It deals with an isolated DC-DC converter which utilizes boost converter topology. The proposed converter is capable of high voltage gain and above all have very high efficiency levels as proved by the simulation results. The project intends to produce an output of 800 V dc from a 48 V dc input. The simulation results obtained from PSIM application interface were used to analyze the performance of the proposed converter. Transformer used in the circuit steps up the voltage as well as to provide electrical isolation between the low voltage and high voltage side. Since the converter involves high switching frequency of 100 kHz, ultrafast recovery diodes are employed in the circuitry. The major application of the project is for future modeling of solar powered electric hybrid cars.

  10. A low-pH medium in vitro or the environment within a macrophage decreases the transcriptional levels of fimA, fimZ and lrp in Salmonella enterica serovar Typhimurium.

    Science.gov (United States)

    Wang, Ke-Chuan; Hsu, Yuan-Hsun; Huang, Yi-Ning; Chen, Ter-Hsin; Lin, Jiunn-Horng; Hsuan, Shih-Ling; Chien, Maw-Sheng; Lee, Wei-Cheng; Yeh, Kuang-Sheng

    2013-09-01

    Many Salmonella Typhimurium isolates produce type 1 fimbriae and exhibit fimbrial phase variation in vitro. Static broth culture favours the production of fimbriae, while solid agar medium inhibits the generation of these appendages. Little information is available regarding whether S. Typhimurium continues to produce type 1 fimbriae during in vivo growth. We used a type 1 fimbrial phase-variable strain S. Typhimurium LB5010 and its derivatives to infect RAW 264.7 macrophages. Following entry into macrophages, S. Typhimurium LB5010 gradually decreased the transcript levels of fimbrial subunit gene fimA, positive regulatory gene fimZ, and global regulatory gene lrp. A similar decrease in transcript levels was detected by RT-PCRwhen the pH of static brothmediumwas shifted frompH 7 to amore acidic pH 4. A fimA-deleted strain continued to multiply within macrophages as did the parental strain. An lrp deletion strain was unimpaired for in vitro growth at pH 7 or pH 4, while a strain harboring an lrp-containing plasmid exhibited impaired in vitro growth at pH 4. We propose that acidic medium, which resembles one aspect of the intracellular environment in a macrophage, inhibits type 1 fimbrial production by down-regulation of the expression of lrp, fimZ and fimA.

  11. LOFT voltage insertion calibaration program

    International Nuclear Information System (INIS)

    Tillitt, D.N.; Miyasaki, F.S.

    1975-08-01

    The Loss-of-Fluid Test (LOFT) Facility is an experimental facility built around a ''scaled'' version of a large pressurized water reactor (LPWR). Part of this facility is the Data Acquisition and Visual Display System (DAVDS) as defined by the LOFT System Design Document SDD 1.4.2C. The DAVDS has a 702 data channel recording capability of which 548 are recorded digitally. The DAVDS also contains a Voltage Insertion Calibration Subsystem used to inject precise and known voltage steps into the recording systems. The computer program that controls the Voltage Insertion Calibration Subsystem is presented. 7 references. (auth)

  12. Thin grain oriented electrical steel for PWM voltages fed magnetic cores

    Science.gov (United States)

    Belgrand, Thierry; Lemaître, Régis; Benabou, Abdelkader; Blaszkowski, Jonathan; Wang, Chaoyong

    2018-04-01

    This paper reports on performances of high permeability grain oriented electrical steel when used in association with power electronic switching devices. Loss measurement results obtained from the Epstein test, using sinusoidal or various PWM voltages in medium frequency range, show that for both studied thicknesses (HGO 0.23mm and HGO 0.18mm), comparing performances at a fixed induction level between the various situations may not be the most convenient method. The effect of magnetic domain refinement has been investigated. After having shown the interest of lowering the thickness, an alternative way of looking at losses is proposed that may help to design the magnetic core when it comes to the matter of reducing size in considering frequency and magnetization levels.

  13. Low Voltage Power Supply Incorporating Ceramic Transformer

    CERN Document Server

    Imori, M

    2007-01-01

    A low voltage power supply provides the regulated output voltage of 1 V from the supply voltage around 48 V. The low voltage power supply incorporates a ceramic transformer which utilizes piezoelectric effect to convert voltage. The ceramic transformer isolates the secondary from the primary, thus providing the ground isolation between the supply and the output voltages. The ceramic transformer takes the place of the conventional magnetic transformer. The ceramic transformer is constructed from a ceramic bar and does not include any magnetic material. So the low voltage power supply can operate under a magnetic field. The output voltage is stabilized by feedback. A feedback loop consists of an error amplifier, a voltage controlled oscillator and a driver circuit. The amplitude ratio of the transformer has dependence on the frequency, which is utilized to stabilize the output voltage. The low voltage power supply is investigated on the analogy of the high voltage power supply similarly incorporating the cerami...

  14. Medium-Detail Delta Morphodynamic Modeling: Initial Experiments with Avulsion Behaviors, Sediment Delivery, Artificial Leeves, and Relative Sea Level Rise Rates

    Science.gov (United States)

    Ratliff, K. M.; Murray, A. B.; Hutton, E. W. H.; Piliouras, A.; Kim, W.

    2014-12-01

    Deltas and their flat, fertile lands have become the most densely populated places on earth, but, partly because of anthropogenic interactions with fluvial, coastal, and wetland processes, their inhabitants are increasingly susceptible to natural disasters. Humans have decreased sediment supply delivered to rivers and ultimately wetlands and the coast, causing accelerating subsidence. The natural course and processes of many rivers have been altered through channelization, artificial levees, and dams, which 'perch' the river above its floodplain. As the rate of relative sea-level rise (RSLR) increases, so will surface aggradation and channel backfilling, resulting in a fluvial system that is more vulnerable to flooding and frequent avulsions. To investigate the effects of increasing RSLR and anthropogenic manipulations on delta morphodynamics, we create new avulsion and floodplain modules to couple with the 3D mode of Sedflux (Hutton and Syvitski, 2008), a stratigraphic basin-filling model. We replace the probabilistic approach of channel avulsion previously used in the model with a module incorporating the steepest-decent methodology used in Jerolmack and Paola (2007), and a floodplain algorithm to deposit sediment on subaerial cells. Model experiments with Sedflux and the new modules address the effects on delta morphodynamics of varying rates of RSLR (affecting base-level), changes in sediment delivery (adjusting the upstream boundary conditions), and restriction of natural fluvial dynamics (inhibiting avulsions). The work presented here is the first step in a more expansive project to develop a new 3D eco-morphodynamic delta model system that will be based on further model couplings, including a vegetation module (that will affect fluvial and floodplain dynamics) and a coastline module (that will re-work the shoreline based on wave-driven alongshore sediment transport). The model system results will be tested and calibrated based on comparisons with

  15. A Voltage Quality Detection Method

    DEFF Research Database (Denmark)

    Chen, Zhe; Wei, Mu

    2008-01-01

    This paper presents a voltage quality detection method based on a phase-locked loop (PLL) technique. The technique can detect the voltage magnitude and phase angle of each individual phase under both normal and fault power system conditions. The proposed method has the potential to evaluate vario...... power quality disturbances, such as interruptions, sags and imbalances. Simulation studies have been performed. The effectiveness of the proposed method has been demonstrated under the simulated typical power disturbances.......This paper presents a voltage quality detection method based on a phase-locked loop (PLL) technique. The technique can detect the voltage magnitude and phase angle of each individual phase under both normal and fault power system conditions. The proposed method has the potential to evaluate various...

  16. Modular High Voltage Power Supply

    Energy Technology Data Exchange (ETDEWEB)

    Newell, Matthew R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-05-18

    The goal of this project is to develop a modular high voltage power supply that will meet the needs of safeguards applications and provide a modular plug and play supply for use with standard electronic racks.

  17. Trace level determination of precious metals in aqueous medium, U, Th and Zr based nuclear materials by ICP-AES and EDXRF - a comparative study

    International Nuclear Information System (INIS)

    Sengupta, Arijit; Thulasidas, S.K.; Natarajan, V.

    2015-01-01

    A comparative study was carried out to determine Ag, Au and Pt in aqueous samples, uranium, zirconium, and thorium based nuclear fuels and associated materials by CCD based ICP-AES and EDXRF. In ICP-AES, the spectral interference of U, Th, Zr matrices on trace level determination of Ag, Au and Pt were studied for different analytical lines of these analytes. The analytical performance of different lines including detection limits, sensitivity, linear dynamic range etc were studied both by ICP-AES and EDXRF. Though EDXRF technique was known its non destructive nature, the overall analytical performance of ICP-AES technique was found to be superior to EDXRF. Based on the spectral contribution from emission rich matrix elements and the analytical performance of different analytical lines of these analytes, a method was developed for direct determination of these analytes by ICP-AES without chemical separation. The method was validated with synthetic samples and compared with EDXRF technique and conventional ICP-AES technique where the major matrix was chemically separated using suitable organic phase containing selective ligands. The ICP-AES method for direct determination of analytes without chemical separation was found to be simple, less time consuming, without generation of organic waste with acceptable analytical performance

  18. Control of improved full-bridge three-level DC/DC converter for wind turbines in a DC grid

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2013-01-01

    This paper presents an improved full-bridge three-level (IFBTL) dc/dc converter for a wind turbine in a dc grid by inserting a passive filter into the dc/dc converter to improve the performance of the converter. The passive filter can effectively reduce the voltage stress of the medium frequency...

  19. Reliability criteria for voltage stability

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Carson W.; Silverstein, Brian L. [Bonneville Power Administration, Portland, OR (United States)

    1994-12-31

    In face of costs pressures, there is need to allocate scare resources more effectively in order to achieve voltage stability. This naturally leads to development of probabilistic criteria and notions of rick management. In this paper it is presented a discussion about criteria for long term voltage stability limited to the case in which the time frames are topically several minutes. (author) 14 refs., 1 fig.

  20. Switched-Capacitor Voltage Multiplier

    Science.gov (United States)

    Sridharan, Govind

    1991-01-01

    Dc-to-dc power converter multiplies input supply potential by factor of nearly 40. Design does not make use of transformers or inductors but effects voltage boost-up by capacitive energy transfer. Circuit primarily made up of banks of capacitors, connected by network of integrated-circuit relays. Converter functionally linear voltage amplifier with fixed gain figure. Bipolar in operation. Output fully floating, and excellent dc isolation between input and output terminals.

  1. Determination of iodine at ppt level in a nitric acid medium by inductively coupled plasma sector field mass spectrometry: influence of the chemical forms

    International Nuclear Information System (INIS)

    Langlois, B.

    2001-01-01

    Inductively Coupled Plasma Sector Field Mass Spectrometry (ICP/SFMS) was used to determine several chemical forms of iodine, at ppt level, in a nitric acid media. Ascorbic acid was added as a reducing agent in order to maintain iodine as iodide. In a preliminary approach, the influence of the chemical form was studied by comparing inorganic iodine (NaI) and organic iodine (CH3I). Different signal responses were observed. With a conventional sample introduction system, sensitivities obtained for iodo-methane could differ by a factor of 5. This was not caused by a problem of atomization or by a change in the ionization efficiency of the iodo-compound into the plasma. The low volatilization temperature of iodo-methane (315.5 K) seemed to be the main explanation of this phenomena. Actually, nebulization resulted in the volatilization of a 2% nitric acid solution containing iodo-methane. As a result, the transport efficiency of iodo-methane between the nebulizer and the torch was approaching 100%. A Direct Injection High Efficiency Nebulizer (DIHEN) allowed us to minimize the behavior difference between the two iodine species, but the sensitivity ratio was inverted and still differed by 20 - 40%. Moreover, the association of a guard electrode and the direct injection system was studied in order to apply these equipments to the determination of iodine. This association allowed us to improve the sensitivity by a factor of 10 and to minimize memory effects, when compared with a conventional system. Further studies indicated that signal responses obtained with different iodine-containing species, except for iodo-methane, were found to be similar. (author)

  2. Macroeconomic Assessment of Voltage Sags

    Directory of Open Access Journals (Sweden)

    Sinan Küfeoğlu

    2016-12-01

    Full Text Available The electric power sector has changed dramatically since the 1980s. Electricity customers are now demanding uninterrupted and high quality service from both utilities and authorities. By becoming more and more dependent on the voltage sensitive electronic equipment, the industry sector is the one which is affected the most by voltage disturbances. Voltage sags are one of the most crucial problems for these customers. The utilities, on the other hand, conduct cost-benefit analyses before going through new investment projects. At this point, understanding the costs of voltage sags become imperative for planning purposes. The characteristics of electric power consumption and hence the susceptibility against voltage sags differ considerably among different industry subsectors. Therefore, a model that will address the estimation of worth of electric power reliability for a large number of customer groups is necessary. This paper introduces a macroeconomic model to calculate Customer Voltage Sag Costs (CVSCs for the industry sector customers. The proposed model makes use of analytical data such as value added, annual energy consumption, working hours, and average outage durations and provides a straightforward, credible, and easy to follow methodology for the estimation of CVSCs.

  3. Response of dairy cattle to transient voltages and magnetic fields

    International Nuclear Information System (INIS)

    Reinemann, D.J.; Laughlin, N.K.; Stetson, L.E.

    1995-01-01

    Stray voltages in dairy facilities have been studied since the 1970's. Previous research using steady-state ac and dc voltages has defined cow-contact voltage levels which may cause behavior and associated production problems. This research was designed to address concerns over possible effects of transient voltages and magnetic fields on dairy cows. Dairy cows response to transient voltages and magnetic fields was measured. The waveforms of the transient voltages applied were: 5 cycles of 60-Hz ac with a total pulse time of 83 ms, 1 cycle of 60-Hz ac with a total pulse time of 16 ms, and 1 cycle of an ac square wave (spiking positive and negative) of 2-ms duration. Alternating magnetic fields were produced by passing 60-Hz ac fundamental frequency with 2nd and 3rd harmonic and random noise components in metal structures around the cows. The maximum magnetic field associated with this current flow was in excess of 4 G. A wide range of sensitivity to transient voltages was observed among cows. Response levels from 24 cows to each transient exposure were normally distributed. No responses to magnetic fields were observed

  4. Integrated differential high-voltage transmitting circuit for CMUTs

    DEFF Research Database (Denmark)

    Llimos Muntal, Pere; Larsen, Dennis Øland; Farch, Kjartan

    2015-01-01

    In this paper an integrated differential high-voltage transmitting circuit for capacitive micromachined ultrasonic transducers (CMUTs) used in portable ultrasound scanners is designed and implemented in a 0.35 μm high-voltage process. Measurements are performed on the integrated circuit in order...... to assess its performance. The circuit generates pulses at differential voltage levels of 60V, 80V and 100 V, a frequency up to 5MHz and a measured driving strength of 1.75 V/ns with the CMUT connected. The total on-chip area occupied by the transmitting circuit is 0.18 mm2 and the power consumption...

  5. Decentralized Voltage Control Coordination of On-Load Tap Changer Transformers, Distributed Generation Units and Flexible Loads

    DEFF Research Database (Denmark)

    Romani Dalmau, Aina; Martinez Perez, David; Diaz de Cerio Mendaza, Iker

    2015-01-01

    approach is introduced in order to coordinate the voltage control capability from different assets in medium voltage networks. In this sense, the on-load tap changer strategy of the primary substation and the power factor control of wind turbines and combined heat and power plants are combined...

  6. Mitigation of voltage sags in the distribution system with dynamic voltage restorer

    International Nuclear Information System (INIS)

    Viglas, D.; Belan, A.

    2012-01-01

    Dynamic voltage restorer is a custom power device that is used to improve voltage sags or swells in electrical distribution system. The components of the Dynamic Voltage Restorer consist of injection transformers, voltage source inverter, passive filters and energy storage. The main function of the Dynamic voltage restorer is used to inject three phase voltage in series and in synchronism with the grid voltages in order to compensate voltage disturbances. This article deals with mitigation of voltage sags caused by three-phase short circuit. Dynamic voltage restorer is modelled in MATLAB/Simulink. (Authors)

  7. 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.

  8. Hadrons in medium

    Indian Academy of Sciences (India)

    medium properties of hadrons. I discuss the relevant symmetries of QCD and how they might affect the observed hadron properties. I then discuss at length the observable consequences of in-medium changes of hadronic properties in reactions with ...

  9. Medium is the message

    NARCIS (Netherlands)

    Kuipers, G.; Ritzer, G.

    2012-01-01

    "The medium is the message" is a phrase coined by Canadian media theorist Marshall McLuhan (1911-1980), in his book Understanding Media: The Extensions of Man (1964). In this book, McLuhan examines the impact of media on societies and human relations, arguing for the primacy of the medium -

  10. Voltage measuring device of a high voltage metalclad installation

    Energy Technology Data Exchange (ETDEWEB)

    Henry, J.; Girard, R.; Kieffer, J.

    1989-06-27

    The low voltage capacitor of a capacitive divider of a metalclad substation is located in a sealed compartment separated from the substation enclosure. In normal operation, the compartment is in direct communication with the enclosure via a communication orifice. The compartment can be isolated from the enclosure by closing the communication orifice valve to drain this compartment and have access to the low voltage capacitor or to the other components of the capacitive divider housed in this compartment. Any pressure or temperature difference between the compartment and the enclosure, liable to affect the measurement, is thus avoided, while authorizing access to the low voltage capacitor without having to drain the whole of the installation.

  11. Electrode voltage fall and total voltage of a transient arc

    Science.gov (United States)

    Valensi, F.; Ratovoson, L.; Razafinimanana, M.; Masquère, M.; Freton, P.; Gleizes, A.

    2016-06-01

    This paper deals with an experimental study of the components of a transient arc total voltage with duration of a few tens of ms and a current peak close to 1000 A. The cathode tip is made of graphite whereas the flat anode is made either of copper or of graphite; the electrodes gap is a few mm. The analysis of the electrical parameters is supported and validated by fast imaging and by two models: the first one is a 2D physical model of the arc allowing to calculate both the plasma temperature field and the arc voltage; the second model is able to estimate the transient heating of the graphite electrode. The main aim of the study was to detect the possible change of the cathode voltage fall (CVF) during the first instants of the arc. Indeed it is expected that during the first ms the graphite cathode is rather cool and the main mechanism of the electron emission should be the field effect emission, whereas after several tens of ms the cathode is strongly heated and thermionic emission should be predominant. We have observed some change in the apparent CVF but we have shown that this apparent change can be attributed to the variation of the solid cathode resistance. On the other hand, the possible change of CVF corresponding to the transition between a ‘cold’ and a ‘hot’ cathode should be weak and could not be characterized considering our measurement uncertainty of about 2 V. The arc column voltage (ACV) was estimated by subtracting the electrode voltage fall from the total arc voltage. The experimental transient evolution of the ACV is in very good agreement with the theoretical variation predicted by the model, showing the good ability of the model to study this kind of transient arc.

  12. Calibration of the ISOLDE acceleration voltage using a high-precision voltage divider and applying collinear fast beam laser spectroscopy

    CERN Document Server

    Krieger, A.; Catherall, R.; Hochschulz, F.; Kramer, J.; Neugart, R.; Rosendahl, S.; Schipper, J.; Siesling, E.; Weinheimer, Ch.; Yordanov, D.T.; Nortershauser, W.

    2011-01-01

    A high-voltage divider with accuracy at the ppm level and collinear laser spectroscopy were used to calibrate the highvoltage installation at the radioactive ion beam facility ISOLDE at CERN. The accurate knowledge of this voltage is particularly important for collinear laser spectroscopy measurements. Beam velocity measurements using frequencycomb based collinear laser spectroscopy agree with the new calibration. Applying this, one obtains consistent results for isotope shifts of stable magnesium isotopes measured using collinear spectroscopy and laser spectroscopy on laser-cooled ions in a trap. The long-term stability and the transient behavior during recovery from a voltage dropout were investigated for the different power supplies currently applied at ISOLDE.

  13. Transient phenomena due to disconnect switching in high voltage substations

    Energy Technology Data Exchange (ETDEWEB)

    Shuette, A. [Siemens AG, Erlangen (Germany); Rodrigo, H. [Royal Melbourne Institute of Technology, Melbourne (Australia). Dept. of Electrical Engineering

    1999-07-01

    Field measurements in a high voltage switchyard during disconnector switching is presented. These measurements are compared with those obtained in a model circuit, set up in our High Voltage laboratory. The need for electromagnetic compatibility in substation equipment, due to its electromagnetic interference is discussed. The level of overvoltage measured in the present work is discussed in the light of those available in the literature. (author)

  14. Huggable communication medium decreases cortisol levels

    OpenAIRE

    Sumioka, Hidenobu; Nakae, Aya; Kanai, Ryota; Ishiguro, Hiroshi

    2013-01-01

    Interpersonal touch is a fundamental component of social interactions because it can mitigate physical and psychological distress. To reproduce the psychological and physiological effects associated with interpersonal touch, interest is growing in introducing tactile sensations to communication devices. However, it remains unknown whether physical contact with such devices can produce objectively measurable endocrine effects like real interpersonal touching can. We directly tested this possib...

  15. Voltage limitations of electrostatic accelerators

    International Nuclear Information System (INIS)

    Hyder, H. R. McK.

    1999-01-01

    The history of electrostatic accelerators has been punctuated by a series of projects in which innovative designs have failed to meet the expectations of their designers. From the early, air-insulated Van de Graaffs at Round Hill to certain of the large pressurized heavy ion accelerators of the 1970s and 1980s, increases in size or changes in design and materials have not always led to the maximum voltages expected or extrapolated. Since these failures have continued beyond childhood into a mature technology, it is reasonable to assume that the causes of voltage limitation are varied and complex. They have remained poorly understood for a number of reasons: resources for an extended program of research into breakdown and failure of electrostatic generators have always been meager, especially for large machines devoted to nuclear research; the inaccessibility of pressurized generators makes instrumentation difficult and testing slow; the calculation of transient and dynamic effects is laborious and the results difficult to verify; voltage test experiments on operating accelerators are inhibited by the significant risk of damage due to energy release on breakdown: and the total voltages (though not the local fields) achieved in many electrostatic accelerators exceed those produced in any other man-made environment. In this review, the behavior of several generators of different designs is examined in order to assess the importance of the various design features and operating conditions that control the maximum voltage achievable in a working machine

  16. Voltage limitations of electrostatic accelerators

    International Nuclear Information System (INIS)

    Hyder, H.R.

    1999-01-01

    The history of electrostatic accelerators has been punctuated by a series of projects in which innovative designs have failed to meet the expectations of their designers. From the early, air-insulated Van de Graaffs at Round Hill to certain of the large pressurized heavy ion accelerators of the 1970s and 1980s, increases in size or changes in design and materials have not always led to the maximum voltages expected or extrapolated. Since these failures have continued beyond childhood into a mature technology, it is reasonable to assume that the causes of voltage limitation are varied and complex. They have remained poorly understood for a number of reasons: resources for an extended program of research into breakdown and failure of electrostatic generators have always been meager, especially for large machines devoted to nuclear research; the inaccessibility of pressurized generators makes instrumentation difficult and testing slow; the calculation of transient and dynamic effects is laborious and the results difficult to verify; voltage test experiments on operating accelerators are inhibited by the significant risk of damage due to energy release on breakdown: and the total voltages (though not the local fields) achieved in many electrostatic accelerators exceed those produced in any other man-made environment. In this review, the behavior of several generators of different designs is examined in order to assess the importance of the various design features and operating conditions that control the maximum voltage achievable in a working machine. copyright 1999 American Institute of Physics

  17. Voltage balancing strategies for serial connection of microbial fuel cells

    Science.gov (United States)

    Khaled, Firas; Ondel, Olivier; Allard, Bruno; Buret, François

    2015-07-01

    The microbial fuel cell (MFC) converts electrochemically organic matter into electricity by means of metabolisms of bacteria. The MFC power output is limited by low voltage and low current characteristics in the range of microwatts or milliwatts per litre. In order to produce a sufficient voltage level (>1.5 V) and sufficient power to supply real applications such as autonomous sensors, it is necessary to either scale-up one single unit or to connect multiple units together. Many topologies of connection are possible as the serial association to improve the output voltage, or the parallel connection to improve the output current or the series/parallel connection to step-up both voltage and current. The association of MFCs in series is a solution to increase the voltage to an acceptable value and to mutualize the unit's output power. The serial association of a large number of MFCs presents several issues. The first one is the hydraulic coupling among MFCs when they share the same substrate. The second one is the dispersion between generators that lead to a non-optimal stack efficiency because the maximum power point (MPP) operation of all MFCs is not permitted. Voltage balancing is a solution to compensate non-uniformities towards MPP. This paper presents solutions to improve the efficiency of a stack of serially connected MFCs through a voltage-balancing circuit. Contribution to the topical issue "Electrical Engineering Symposium (SGE 2014)", edited by Adel Razek

  18. Secondary Control for Voltage Quality Enhancement in Microgrids

    DEFF Research Database (Denmark)

    Savaghebi, Mehdi; Jalilian, Alireza; Vasquez, Juan Carlos

    2012-01-01

    In this paper, a hierarchical control scheme is proposed for enhancement of sensitive load bus (SLB) voltage quality in microgrids. The control structure consists of primary and secondary levels. The primary control level comprises distributed generators (DGs) local controllers. Each...... level is applied to manage the compensation of SLB voltage unbalance and harmonics by sending proper control signals to the primary level. DGs compensation efforts are controlled locally at the primary level. The system design procedure for selecting proper control parameters is discussed. Simulation...... of these controllers includes a selective virtual impedance loop which is considered to improve sharing of fundamental and harmonic components of load current among the DG units. The sharing improvement is provided at the expense of increasing voltage unbalance and harmonic distortion. Thus, the secondary control...

  19. Voltage Control of Magnetic Anisotropy

    Science.gov (United States)

    Hao, Guanhua; Cao, Shi; Noviasky, Nick; Ilie, Carolina; Sokolov, Andre; Yin, Yuewei; Xu, Xiaoshan; Dowben, Peter

    Pd/Co/Gd2O3/Si heterostructures were fabricated via pulsed laser deposition and e-beam evaporation. Hysteresis loops, obtained by longitudinal magneto-optical Kerr-effect (MOKE) measurements, indicates an initial in-plane magnetic anisotropy. Applying a perpendicular voltage on the sample, the differences between the polar and longitudinal MOKE and anomalous Hall effect data indicates there is a reversible change in magnetic anisotropy, from in-plane to out-of-plane, with applied voltage. Prior work by others suggests that the change in magnetic anisotropy is due to redox reactions at the Co/Gd2O3 interference. Voltage controlled magnetism can result from changing interfacial chemistry and does not always require a magneto-electric coupling tensor.

  20. Ancillary service details: Voltage control

    Energy Technology Data Exchange (ETDEWEB)

    Kirby, B.; Hirst, E.

    1997-12-01

    Voltage control is accomplished by managing reactive power on an alternating-current power system. Reactive power can be produced and absorbed by both generation and transmission equipment. Reactive-power devices differ substantially in the magnitude and speed of response and in their capital costs. System operators, transmission owners, generators, customers, power marketers, and government regulators need to pay close attention to voltage control as they restructure the U.S. electricity industry. Voltage control can affect reliability and commerce in three ways: (1) Voltages must be maintained within an acceptable range for both customer and power-system equipment to function properly. (2) The movement of reactive power consumes transmission resources, which limits the ability to move real power and worsens congestion. (3) The movement of reactive power results in real-power losses. When generators are required to supply excessive amounts of reactive power, their real-power production must be curtailed. These opportunity costs are not currently compensated for in most regions. Current tariffs are based on embedded costs. These embedded-cost tariffs average about $0.51/MWh, equivalent to $1.5 billion annually for the United States as a whole. Although this cost is low when compared with the cost of energy, it still aggregates to a significant amount of money. This report takes a basic look at why the power system requires reactive power (an appendix explains the fundamentals of real and reactive power). The report then examines the various types of generation and transmission resources used to supply reactive power and to control voltage. Finally it discusses how these resources are deployed and paid for in several reliability regions around the country. As the U.S. electricity industry is restructured, the generation, transmission, and system-control equipment and functions that maintain voltages within the appropriate ranges are being deintegrated.

  1. Local interstellar medium

    International Nuclear Information System (INIS)

    Crutcher, R.M.; and Radio Astronomy Laboratory, University of California, Berkeley)

    1982-01-01

    Analysis of the velocities of optical interstellar lines shows that the Sun is immersed in a coherently moving local interstellar medium whose velocity vector agrees with that of the interstellar wind observed through backscatter of solar H Lyα and He lambda584 photons. The local interstellar medium consists of both cool clouds and warm intercloud medium gas, has a mass of perhaps approx.30 M/sub sun/, does not have severe depletion of trace elements from the gas phase, and appears to be material which has been shocked and accelerated by stellar winds and supernovae associated with the Sco-Oph OB association

  2. CNTF inhibits high voltage activated Ca2+ currents in fetal mouse cortical neurones

    DEFF Research Database (Denmark)

    Holm, Ninna R; Christophersen, Palle; Hounsgaard, Jørn

    2002-01-01

    Neurotrophic factors yield neuroprotection by mechanisms that may be related to their effects as inhibitors of apoptosis as well as their effects on ion channels. The effect of ciliary neurotrophic factor (CNTF) on high-threshold voltage-activated Ca channels in cultured fetal mouse brain cortical...... neurones was investigated. Addition of CNTF into serum-free growth medium resulted in delayed reduction of the Ca2+ currents. The currents decreased to 50% after 4 h and stabilized at this level during incubation with CNTF for 48 h. Following removal of CNTF the inhibition was completely reversed after 18...... h. CNTF reduced the current of all pharmacological subtypes of Ca channels as shown by use of selective blockers of L, N, and P/Q type Ca channels (nifedipine, omega-conotoxin MVIIA, omega-agatoxin IVA). The Ca channel depression was mediated via the CNTF receptor, because enzymatic cleavage...

  3. Design and Implementation of a High-Voltage Generator with Output Voltage Control for Vehicle ER Shock-Absorber Applications

    Directory of Open Access Journals (Sweden)

    Chih-Lung Shen

    2013-01-01

    Full Text Available A self-oscillating high-voltage generator is proposed to supply voltage for a suspension system in order to control the damping force of an electrorheological (ER fluid shock absorber. By controlling the output voltage level of the generator, the damping force in the ER fluid shock absorber can be adjusted immediately. The shock absorber is part of the suspension system. The high-voltage generator drives a power transistor based on self-excited oscillation, which converts dc to ac. A high-frequency transformer with high turns ratio is used to increase the voltage. In addition, the system uses the car battery as dc power supply. By regulating the duty cycle of the main switch in the buck converter, the output voltage of the buck converter can be linearly adjusted so as to obtain a specific high voltage for ER. The driving system is self-excited; that is, no additional external driving circuit is required. Thus, it reduces cost and simplifies system structure. A prototype version of the actual product is studied to measure and evaluate the key waveforms. The feasibility of the proposed system is verified based on experimental results.

  4. Resilient architecture design for voltage variation

    CERN Document Server

    Reddi, Vijay Janapa

    2013-01-01

    Shrinking feature size and diminishing supply voltage are making circuits sensitive to supply voltage fluctuations within the microprocessor, caused by normal workload activity changes. If left unattended, voltage fluctuations can lead to timing violations or even transistor lifetime issues that degrade processor robustness. Mechanisms that learn to tolerate, avoid, and eliminate voltage fluctuations based on program and microarchitectural events can help steer the processor clear of danger, thus enabling tighter voltage margins that improve performance or lower power consumption. We describe

  5. Numerical analysis on the effect of voltage change on removing condensed water inside the GDL of a PEM fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Nam Woo [Fuel Cell Technology Development Team, Eco-Technology Center, Hyundai-Kia Motors, Yongin (Korea, Republic of); Kim, Young Sang; Kim, Min Soo [Dept. of Mechanical and Aerospace Engineering, Seoul National University, Seoul (Korea, Republic of); Kim, Min Sung [School of Energy Systems Engineering, Chung-Ang University, Seoul (Korea, Republic of)

    2016-09-15

    Decreasing the voltage of a fuel cell through hydrogen mixing or using low-air stoichiometry ratio is beneficial to remove condensed water inside GDL under flooding condition. In this study, the effect of voltage level of a fuel cell on water distribution in GDL under flooding condition was numerically analyzed. Water content in GDL was dependent on the voltage level of a fuel cell, that is, the water content was low when the cell voltage was maintained low. The effect of voltage change under flooding condition was also simulated. The flow rate of condensed water inside GDL considerably increased immediately after decreasing the cell voltage. The oxygen concentration in the catalyst layer was increased by decreasing the voltage of the fuel cell. Consequently, the cell voltage was recovered. Therefore, decreasing cell voltage under flooding condition can facilitate removal of condensed water in GDL.

  6. DC Voltage Control and Power-Sharing of Multi-Terminal DC Grids Based on Optimal DC Power Flow and Flexible Voltage Droop Strategy

    Directory of Open Access Journals (Sweden)

    F. Azma

    2015-06-01

    Full Text Available This paper develops an effective control framework for DC voltage control and power-sharing of multi-terminal DC (MTDC grids based on an optimal power flow (OPF procedure and the voltage-droop control. In the proposed approach, an OPF algorithm is executed at the secondary level to find optimal reference of DC voltages and active powers of all voltage-regulating converters. Then, the voltage droop characteristics of voltage-regulating converters, at the primary level, are tuned based on the OPF results such that the operating point of the MTDC grid lies on the voltage droop characteristics. Consequently, the optimally-tuned voltage droop controller leads to the optimal operation of the MTDC grid. In case of variation in load or generation of the grid, a new stable operating point is achieved based on the voltage droop characteristics. By execution of a new OPF, the voltage droop characteristics are re-tuned for optimal operation of the MTDC grid after the occurrence of the load or generation variations. The results of simulation on a grid inspired by CIGRE B4 DC grid test system demonstrate efficient grid performance under the proposed control strategy.

  7. Reduction of Coronary Motion Artifacts in Prospectively Electrocardiography-Gated Coronary Computed Tomography Angiography Using Monochromatic Imaging at Various Energy Levels in Combination With a Motion Correction Algorithm on Single-Source Fast Tube Voltage Switching Dual-Energy Computed Tomography: A Phantom Experiment.

    Science.gov (United States)

    Machida, Haruhiko; Fukui, Rika; Gao, Jianbo; Tanaka, Isao; Shen, Yun; Suzuki, Shigeru; Ishikawa, Takuya; Ueno, Eiko

    2016-08-01

    The aim of this study was to assess the effect of monochromatic imaging at various energy levels in combination with a motion correction algorithm (MCA) in single-source dual-energy coronary computed tomography angiography (CCTA) with fast switching of tube voltage on the reduction of coronary motion artifacts (CMA) in a phantom setting. Using this dual-energy computed tomography technique with a phantom comprising models of coronary vessels filled with contrast medium and pulsating at constant heart rates of 60 to 100 beats per minute, we reconstructed monochromatic images of CCTA obtained at 50 to 90 keV with and without use of MCA. Cardiac motion was modeled by simulating the in vivo time-volume curve of the left ventricle. Two independent readers graded CMA in 9 coronary segments using a 5-point scale (1, poor; 3 to 5, interpretable; 5, excellent). At each heart rate, we compared the average score of CMA between images obtained at 50 to 90 keV with and without use of MCA using Wilcoxon signed rank test, and we compared the score among images obtained at 50 to 90 keV with use of MCA using Kruskal-Wallis and post hoc tests. We also compared the percentages of image interpretability and improvement in image interpretability among images obtained at 50 to 90 keV with use of MCA. With the use of MCA, the average score of CMA was significantly higher for images obtained at each energy level from 50 to 70 keV (P < 0.05) and was comparable at 80 and 90 keV, and it was comparable among those obtained at 50 to 70 keV. With its use, the percentages of image interpretability were similarly high at 50 to 70 keV at 60 to 80 beats per minute (78%-100%), and they were higher at 50 to 60 keV (72%-83%) than at 70 keV at 90 to 100 beats per minute (50%-56%). The percentages of improved image interpretability with MCA were similarly high at 50 to 70 keV at 60 to 80 beats per minute (56%-100%), and they were higher at 50 to 60 keV (62%-77%) than at 70 keV at 90 to 100 beats per

  8. High-voltage integrated linear regulator with current sinking capabilities for portable ultrasound scanners

    DEFF Research Database (Denmark)

    Pausas, Guifre Vendrell; Llimos Muntal, Pere; Jørgensen, Ivan Harald Holger

    2017-01-01

    This paper presents a high-voltage integrated regulator capable of sinking current for driving pulse-triggered level shifters in drivers for ultrasound applications. The regulator utilizes a new topology with a feedback loop and a current sinking circuit to satisfy the requirements of the portable...... ultrasound scanner: a great driving strength in the scanner's transducer and a low undershoot voltage in the output node. The design regulates an output voltage of 45 V from an input voltage of 50 V, and it can sink currents up to 100 mA using no external components with only 340 mV of undershoot voltage...

  9. HIRENASD medium unstructured

    Data.gov (United States)

    National Aeronautics and Space Administration — Unstructured HIRENASD mesh: - medium size (16 million nodes, 39 million elements) - for node centered solvers - 31.05.2011 - caution: dimensions in mm

  10. Concept medium programme

    DEFF Research Database (Denmark)

    Bjerrum, Peter

    2005-01-01

    The present essay is an attempt to determine the architectural project of the 21st century in relation to a modern conception of space as the medium of architecture, and of sociality as its program...

  11. High-voltage air-core pulse transformers

    Energy Technology Data Exchange (ETDEWEB)

    Rohwein, G. J.

    1981-01-01

    General types of air core pulse transformers designed for high voltage pulse generation and energy transfer applications are discussed with special emphasis on pulse charging systems which operate up to the multi-megavolt range. The design, operation, dielectric materials, and performance are described. It is concluded that high voltage air core pulse transformers are best suited to applications outside the normal ranges of conventional magnetic core transformers. In general these include charge transfer at high power levels and fast pulse generation with comparatively low energy. When properly designed and constructed, they are capable of delivering high energy transfer efficiency and have demonstrated superior high voltage endurance. The principal disadvantage of high voltage air core transformers is that they are not generally available from commercial sources. Consequently, the potential user must become thoroughly familiar with all aspects of design, fabrication and system application before he can produce a high performance transformer system. (LCL)

  12. Concept medium programme

    DEFF Research Database (Denmark)

    Bjerrum, Peter

    2005-01-01

    The present essay is an attempt to determine the architectural project of the 21st century in relation to a modern conception of space as the medium of architecture, and of sociality as its program......The present essay is an attempt to determine the architectural project of the 21st century in relation to a modern conception of space as the medium of architecture, and of sociality as its program...

  13. On-chip High-Voltage Generator Design

    CERN Document Server

    Tanzawa, Toru

    2013-01-01

    This book describes high-voltage generator design with switched-capacitor multiplier techniques.  The author provides various design techniques for switched-capacitor on-chip high-voltage generators, including charge pump circuits, regulators, level shifters, references, and oscillators.  Readers will see these techniques applied to system design in order to address the challenge of how the on-chip high-voltage generator is designed for Flash memories, LCD drivers, and other semiconductor devices to optimize the entire circuit area and power efficiency with a low voltage supply, while minimizing the cost.   ·         Shows readers how to design charge pump circuits with lower voltage operation, higher power efficiency, and smaller circuit area; ·         Describes comprehensive circuits and systems design of on-chip high-voltage generators; ·         Covers all the component circuit blocks, including charge pumps, pump regulators, level shifters, oscillators, and references.

  14. Mobile high-voltage switchboard. Variable and uncomplicated; Mobile Hochspannungsschaltanlage. Variabel und unkompliziert in der Anwendung

    Energy Technology Data Exchange (ETDEWEB)

    Albert, Andreas [Siemens AG, Erlangen (Germany). Sector Energy

    2009-07-13

    The mobile high-voltage switchboard ''REE-Movil 2'' for voltages up to 245 kV provides a complete and nearly autonomous switchboard in a container, a solution that has been available in the medium-voltage sector for some time already. It can be used whenever a quick replacement of a switchboard section or a temporary supplement to a switching substation is needed. The container is mounted on a trailer for maximum flexibility and mobility. (orig.)

  15. Voltage Weak DC Distribution Grids

    NARCIS (Netherlands)

    Hailu, T.G.; Mackay, L.J.; Ramirez Elizondo, L.M.; Ferreira, J.A.

    2017-01-01

    This paper describes the behavior of voltage weak DC distribution systems. These systems have relatively small system capacitance. The size of system capacitance, which stores energy, has a considerable effect on the value of fault currents, control complexity, and system reliability. A number of

  16. High voltage power network construction

    CERN Document Server

    Harker, Keith

    2018-01-01

    This book examines the key requirements, considerations, complexities and constraints relevant to the task of high voltage power network construction, from design, finance, contracts and project management to installation and commissioning, with the aim of providing an overview of the holistic end to end construction task in a single volume.

  17. High-Voltage Droplet Dispenser

    Science.gov (United States)

    Eichenberg, Dennis J.

    2003-01-01

    An apparatus that is extremely effective in dispensing a wide range of droplets has been developed. This droplet dispenser is unique in that it utilizes a droplet bias voltage, as well as an ionization pulse, to release a droplet. Apparatuses that deploy individual droplets have been used in many applications, including, notably, study of combustion of liquid fuels. Experiments on isolated droplets are useful in that they enable the study of droplet phenomena under well-controlled and simplified conditions. In this apparatus, a syringe dispenses a known value of liquid, which emerges from, and hangs onto, the outer end of a flat-tipped, stainless steel needle. Somewhat below the needle tip and droplet is a ring electrode. A bias high voltage, followed by a high-voltage pulse, is applied so as to attract the droplet sufficiently to pull it off the needle. The voltages are such that the droplet and needle are negatively charged and the ring electrode is positively charged.

  18. Voltage control of ferromagnetic resonance

    Directory of Open Access Journals (Sweden)

    Ziyao Zhou

    2016-06-01

    Full Text Available Voltage control of magnetism in multiferroics, where the ferromagnetism and ferroelectricity are simultaneously exhibiting, is of great importance to achieve compact, fast and energy efficient voltage controllable magnetic/microwave devices. Particularly, these devices are widely used in radar, aircraft, cell phones and satellites, where volume, response time and energy consumption is critical. Researchers realized electric field tuning of magnetic properties like magnetization, magnetic anisotropy and permeability in varied multiferroic heterostructures such as bulk, thin films and nanostructure by different magnetoelectric (ME coupling mechanism: strain/stress, interfacial charge, spin–electromagnetic (EM coupling and exchange coupling, etc. In this review, we focus on voltage control of ferromagnetic resonance (FMR in multiferroics. ME coupling-induced FMR change is critical in microwave devices, where the electric field tuning of magnetic effective anisotropic field determines the tunability of the performance of microwave devices. Experimentally, FMR measurement technique is also an important method to determine the small effective magnetic field change in small amount of magnetic material precisely due to its high sensitivity and to reveal the deep science of multiferroics, especially, voltage control of magnetism in novel mechanisms like interfacial charge, spin–EM coupling and exchange coupling.

  19. Fast solid state high voltage pulse generator

    Science.gov (United States)

    Christiansen, Jens; Frank, Klaus; Hartmann, Werner

    1987-05-01

    A fast solid state pulse generator is described which is used to trigger high voltage, high current switches. It consists of a 7-stage marx generator bank switched by avalanche transistors and delivers a negative pulse with a rise time of less than 2 ns and an amplitude of 2.4 kV into a load of 200 ω. The delay between the trigger pulse of TTL level and the output pulse is 16 ns. The jitter is well below 100 ps.

  20. Voltage linear transformation circuit design

    Science.gov (United States)

    Sanchez, Lucas R. W.; Jin, Moon-Seob; Scott, R. Phillip; Luder, Ryan J.; Hart, Michael

    2017-09-01

    Many engineering projects require automated control of analog voltages over a specified range. We have developed a computer interface comprising custom hardware and MATLAB code to provide real-time control of a Thorlabs adaptive optics (AO) kit. The hardware interface includes an op amp cascade to linearly shift and scale a voltage range. With easy modifications, any linear transformation can be accommodated. In AO applications, the design is suitable to drive a range of different types of deformable and fast steering mirrors (FSM's). Our original motivation and application was to control an Optics in Motion (OIM) FSM which requires the customer to devise a unique interface to supply voltages to the mirror controller to set the mirror's angular deflection. The FSM is in an optical servo loop with a wave front sensor (WFS), which controls the dynamic behavior of the mirror's deflection. The code acquires wavefront data from the WFS and fits a plane, which is subsequently converted into its corresponding angular deflection. The FSM provides +/-3° optical angular deflection for a +/-10 V voltage swing. Voltages are applied to the mirror via a National Instruments digital-to-analog converter (DAC) followed by an op amp cascade circuit. This system has been integrated into our Thorlabs AO testbed which currently runs at 11 Hz, but with planned software upgrades, the system update rate is expected to improve to 500 Hz. To show that the FSM subsystem is ready for this speed, we conducted two different PID tuning runs at different step commands. Once 500 Hz is achieved, we plan to make the code and method for our interface solution freely available to the community.

  1. Voltage-gated Proton Channels

    Science.gov (United States)

    DeCoursey, Thomas E.

    2014-01-01

    Voltage-gated proton channels, HV1, have vaulted from the realm of the esoteric into the forefront of a central question facing ion channel biophysicists, namely the mechanism by which voltage-dependent gating occurs. This transformation is the result of several factors. Identification of the gene in 2006 revealed that proton channels are homologues of the voltage-sensing domain of most other voltage-gated ion channels. Unique, or at least eccentric, properties of proton channels include dimeric architecture with dual conduction pathways, perfect proton selectivity, a single-channel conductance ~103 smaller than most ion channels, voltage-dependent gating that is strongly modulated by the pH gradient, ΔpH, and potent inhibition by Zn2+ (in many species) but an absence of other potent inhibitors. The recent identification of HV1 in three unicellular marine plankton species has dramatically expanded the phylogenetic family tree. Interest in proton channels in their own right has increased as important physiological roles have been identified in many cells. Proton channels trigger the bioluminescent flash of dinoflagellates, facilitate calcification by coccolithophores, regulate pH-dependent processes in eggs and sperm during fertilization, secrete acid to control the pH of airway fluids, facilitate histamine secretion by basophils, and play a signaling role in facilitating B-cell receptor mediated responses in B lymphocytes. The most elaborate and best-established functions occur in phagocytes, where proton channels optimize the activity of NADPH oxidase, an important producer of reactive oxygen species. Proton efflux mediated by HV1 balances the charge translocated across the membrane by electrons through NADPH oxidase, minimizes changes in cytoplasmic and phagosomal pH, limits osmotic swelling of the phagosome, and provides substrate H+ for the production of H2O2 and HOCl, reactive oxygen species crucial to killing pathogens. PMID:23798303

  2. Defined medium for Moraxella bovis.

    OpenAIRE

    Juni, E; Heym, G A

    1986-01-01

    A defined medium (medium MB) for Moraxella bovis was formulated. Nineteen strains grew well on medium MB. One strain was auxotrophic for asparagine, and another was auxotrophic for methionine. Strains of M. equi and M. lacunata also grew on medium MB. All strains had an absolute requirement for thiamine and were stimulated by or actually required the other growth factors in the medium.

  3. PENGARUH TEGANGAN ELEKTROPORASI TERHADAP EFISIENSI TRANSFORMASI PLAMID pND968 BAKTERI ASAM LAKTAT KE E. coli HB101 [The Effect of Electroporation Voltage on Transformation Efficiency of Plasmid pND968 of Lactic Acid Bacteria Into E. coli HB101

    OpenAIRE

    Widodo

    2002-01-01

    The research was conducted to examine the effect of different electroporation voltage on transformation efficiency of plasmid pND968. This was carried out by exposing the mixture of plasmid pND968 and competent cells of E. coli HB101 on a difference level of electroporation voltage at 1500, 2000 and 2500 Volts. After electroporation, the cells were resuspended in a recovery medium and then poured into ampicilin-containing LB agar. Transformants appeared after 48-72 hours were then recorded....

  4. Voltage Impacts of Utility-Scale Distributed Wind

    Energy Technology Data Exchange (ETDEWEB)

    Allen, A.

    2014-09-01

    Although most utility-scale wind turbines in the United States are added at the transmission level in large wind power plants, distributed wind power offers an alternative that could increase the overall wind power penetration without the need for additional transmission. This report examines the distribution feeder-level voltage issues that can arise when adding utility-scale wind turbines to the distribution system. Four of the Pacific Northwest National Laboratory taxonomy feeders were examined in detail to study the voltage issues associated with adding wind turbines at different distances from the sub-station. General rules relating feeder resistance up to the point of turbine interconnection to the expected maximum voltage change levels were developed. Additional analysis examined line and transformer overvoltage conditions.

  5. Prediction of windings temperature rise in induction motors supplied with distorted voltage

    International Nuclear Information System (INIS)

    Gnacinski, P.

    2008-01-01

    One of the features of ship power systems is a different level and intensity of disturbances appearing during routine operation - the rms voltage value and frequency deviation, voltage unbalance and waveform voltage distortion. As a result, marine induction machines are exposed to overheating due to the lowered voltage quality. This paper is devoted to windings temperature rise prediction in marine induction cage machines supplied with distorted voltage, which means real voltage conditions. The proposed method of prediction does not require detailed knowledge of the thermal properties of a machine. Although the method was developed for marine induction motors, it is applicable for industry machines supplied with distorted voltage. It can also be generalized and used for estimation of the steady state windings temperature rise of any electrical machinery in various work conditions

  6. First high-voltage measurements using Ca{sup +} ions at the ALIVE experiment

    Energy Technology Data Exchange (ETDEWEB)

    König, K., E-mail: kkoenig@ikp.tu-darmstadt.de [Technische Universität Darmstadt, Institut für Kernphysik (Germany); Geppert, Ch. [Universität Mainz, Institut für Kernchemie (Germany); Krämer, J.; Maaß, B. [Technische Universität Darmstadt, Institut für Kernphysik (Germany); Otten, E. W. [Universität Mainz, Institut für Physik (Germany); Ratajczyk, T.; Nörtershäuser, W. [Technische Universität Darmstadt, Institut für Kernphysik (Germany)

    2017-11-15

    Many physics experiments depend on accurate high-voltage measurements to determine for example the exact retardation potential of an electron spectrometer as in the KATRIN experiment or the acceleration voltage of the ions at ISOL facilities. Until now only precision high-voltage dividers can be used to measure voltages up to 65 kV with an accuracy of 1 ppm. However, these dividers need frequent calibration and cross-checking and the direct traceability is not given. In this article we will describe the status of an experiment which aims to measure high voltages using collinear laser spectroscopy and which has the potential to provide a high-voltage standard and hence, a calibration source for precision high-voltage dividers on the 1 ppm level.

  7. First high-voltage measurements using Ca+ ions at the ALIVE experiment

    Science.gov (United States)

    König, K.; Geppert, Ch.; Krämer, J.; Maaß, B.; Otten, E. W.; Ratajczyk, T.; Nörtershäuser, W.

    2017-11-01

    Many physics experiments depend on accurate high-voltage measurements to determine for example the exact retardation potential of an electron spectrometer as in the KATRIN experiment or the acceleration voltage of the ions at ISOL facilities. Until now only precision high-voltage dividers can be used to measure voltages up to 65 kV with an accuracy of 1 ppm. However, these dividers need frequent calibration and cross-checking and the direct traceability is not given. In this article we will describe the status of an experiment which aims to measure high voltages using collinear laser spectroscopy and which has the potential to provide a high-voltage standard and hence, a calibration source for precision high-voltage dividers on the 1 ppm level.

  8. Spiegel. Medium. Kunst

    DEFF Research Database (Denmark)

    Kacunko, Slavko

    and cultural perspective. From 1800 on, the great incentive was to push forward the material-physical and optical-mechanical and especially the media ‘exploitation’ of the mirror. The significance of the mirror as a central meta-medium of the visual emerged in a particularly striking way in the late 1830s....... That ricochets through media theory, theories of art and culture and through cultural historiography. A repository is one thing, a transmitter another: the distinction will act crucially on the quest for appropriate perspectives and classifications of what in terms of disciplines would rather appear...... or as synaesthesia gone mute. It stands in contrast with the mirror, which assumes the status of a medium facility or meta-medium of visual transference, encountering its only medial and operative limitation within the analogue or digital repository media. The present proposal for an artistic and cultural history...

  9. Over-voltage protection system and method

    Science.gov (United States)

    Chi, Song; Dong, Dong; Lai, Rixin

    2017-05-02

    An over-voltage protection system includes an electronic valve connected across two terminals of a circuit and an over-voltage detection circuit connected across one of the plurality of semiconductor devices for detecting an over-voltage across the circuit. The electronic valve includes a plurality of semiconductor devices connected in series. The over-voltage detection circuit includes a voltage divider circuit connected to a break-over diode in a way to provide a representative low voltage to the break-over diode and an optocoupler configured to receive a current from the break-over diode when the representative low voltage exceeds a threshold voltage of the break-over diode indicating an over-voltage condition. The representative low voltage provided to the break-over diode represents a voltage across the one semiconductor device. A plurality of self-powered gate drive circuits are connected to the plurality of semiconductor devices, wherein the plurality of self-powered gate drive circuits receive over-voltage triggering pulses from the optocoupler during the over-voltage condition and switch on the plurality of semiconductor devices to bypass the circuit.

  10. A Netherlands approach for assessing the performance and the long-term safety aspects of a high-level waste repository to be mined in a medium-sized salt dome

    International Nuclear Information System (INIS)

    Glasbergen, P.; Janssen, L.G.J.; Hamstra, J.

    1987-01-01

    This report describes the performance assessment work that is being carried out under contract to the European Commission in order to evaluate the isolation capability of a salt dome that is to be used for the disposal of high-level waste. The work is based on the assumption that the normal evolution scenario for radionuclide release from a repository that is mined in a medium size salt dome will be a continuous subrosion of the salt dome. This report is a compilation of the three progress reports published on this subject. It reviews the general regional setting of The Netherlands' reference salt dome and the consideration that led to the new approach in geohydrological modelling. This modelling is based on the assumptions thet the subrosion started 1.2 x 10 6 years ago and that the future climatic changes remain limited to a continuing Quaternary type of development in average temperatures. It describes the composition of the model used for calculating the subrosion rate with the use of a modified version of the SWIP-2-computer code. And it gives the results of the calculations on both the flank and top subrosion. The main conclusion is that even under very conservative assumptions the calculated subrosion rates are so small that the isolation capability of a salt dome with an adequately designed repository is at least in the order of a million of years

  11. Medium Theory and Social Systems

    DEFF Research Database (Denmark)

    Tække, Jesper

    The  paper  first  gives  a  tentative  theoretical  explanation  of  the  concept  of media,  based  on  the  dichotomies  of  actual/potential  (meaning),  form/medium  (appearance),  and  substratum/material  content  (extension  in  time  and  space).  This  theoretical  explanation  presents......  seen as medium  for  formation. Finally  the  paper  takes  the micro  level  perspective  by  applying  the  theory  to  newsgroups,  interpreting  them as self-organizing interactive systems giving a differentiated and diversified scope for social  inclusion.  ......The  paper  first  gives  a  tentative  theoretical  explanation  of  the  concept  of media,  based  on  the  dichotomies  of  actual/potential  (meaning),  form/medium  (appearance),  and  substratum/material  content  (extension  in  time  and  space).  This  theoretical  explanation  presents......  the  possibility  for  observation both of a social micro and a social macro level from a medium perspective. In the next  section  the paper  frames  the macro  level by  a  tentative  synthesis of  the medium  theory  and  the  sociological systems theory briefly describing a socio...

  12. Analyzing randomly occurring voltage breakdowns

    International Nuclear Information System (INIS)

    Wiltshire, C.W.

    1977-01-01

    During acceptance testing of high-vacuum neutron tubes, 40% of the tubes failed after experiencing high-voltage breakdowns during the aging process. Use of a digitizer in place of an oscilloscope revealed two types of breakdowns, only one of which affected acceptance testing. This information allowed redesign of the aging sequence to prevent tube damage and improve yield and quality of the final product

  13. TRANSISTOR HIGH VOLTAGE POWER SUPPLY

    Science.gov (United States)

    Driver, G.E.

    1958-07-15

    High voltage, direct current power supplies are described for use with battery powered nuclear detection equipment. The particular advantages of the power supply described, are increased efficiency and reduced size and welght brought about by the use of transistors in the circuit. An important feature resides tn the employment of a pair of transistors in an alternatefiring oscillator circuit having a coupling transformer and other circuit components which are used for interconnecting the various electrodes of the transistors.

  14. Advances in high voltage engineering

    CERN Document Server

    Haddad, A

    2005-01-01

    This book addresses the very latest research and development issues in high voltage technology and is intended as a reference source for researchers and students in the field, specifically covering developments throughout the past decade. This unique blend of expert authors and comprehensive subject coverage means that this book is ideally suited as a reference source for engineers and academics in the field for years to come.

  15. High-Voltage, Asymmetric-Waveform Generator

    Science.gov (United States)

    Beegle, Luther W.; Duong, Tuan A.; Duong, Vu A.; Kanik, Isik

    2008-01-01

    leave the fundamental timing signal unchanged. The buffered timing signal would be fed as input to the level shifter. The output of the level shifter would serve as a timing and control signal for the high-voltage switch, causing the switch to alternately be (1) opened, allowing the capacitive load to be charged from a high-voltage DC power supply; then (2) closed to discharge the capacitive load to ground. Hence, the output waveform would closely approximate a series of exponential charging and discharging curves (see Figure 2).

  16. Impact of distributed generators on the power loss and voltage profile of sub-transmission network

    Directory of Open Access Journals (Sweden)

    A.S.O. Ogunjuyigbe

    2016-05-01

    Full Text Available This paper presents the impact of distributed generator (DG on the power loss and voltage profile of sub-transmission network at different penetration levels (PLs. The various DG technologies are modeled based on their electrical output characteristics. Voltage profile index which allows a single value to represent how well the voltage matches the ideal value is developed. The index allows a fair comparison of the voltage profile obtained from different scenarios. The extent to which DGs affect power losses and voltage profile depend on the type of DG technology, PL and the location in which the DG is connected to the grid. The integration of DGs reduces power losses on the network, however, as the PL increases, the power losses begin to increase. A PL of 50–75% is achieved on 69 kV voltage level and 25–50% penetration on 13.8 kV voltage level without an increase in the power loss. Also more DG can be integrated into the network at point of common connection of higher voltage level compared to the low voltage level.

  17. Low voltage electron beam accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Ochi, Masafumi [Iwasaki Electric Co., Ltd., Tokyo (Japan)

    2003-02-01

    Widely used electron accelerators in industries are the electron beams with acceleration voltage at 300 kV or less. The typical examples are shown on manufactures in Japan, equipment configuration, operation, determination of process parameters, and basic maintenance requirement of the electron beam processors. New electron beam processors with acceleration voltage around 100 kV were introduced maintaining the relatively high dose speed capability of around 10,000 kGy x mpm at production by ESI (Energy Science Inc. USA, Iwasaki Electric Group). The application field like printing and coating for packaging requires treating thickness of 30 micron or less. It does not require high voltage over 110 kV. Also recently developed is a miniature bulb type electron beam tube with energy less than 60 kV. The new application area for this new electron beam tube is being searched. The drive force of this technology to spread in the industries would be further development of new application, process and market as well as the price reduction of the equipment, upon which further acknowledgement and acceptance of the technology to societies and industries would entirely depend. (Y. Tanaka)

  18. Thermoelectric spin voltage in graphene.

    Science.gov (United States)

    Sierra, Juan F; Neumann, Ingmar; Cuppens, Jo; Raes, Bart; Costache, Marius V; Valenzuela, Sergio O

    2018-02-01

    In recent years, new spin-dependent thermal effects have been discovered in ferromagnets, stimulating a growing interest in spin caloritronics, a field that exploits the interaction between spin and heat currents 1,2 . Amongst the most intriguing phenomena is the spin Seebeck effect 3-5 , in which a thermal gradient gives rise to spin currents that are detected through the inverse spin Hall effect 6-8 . Non-magnetic materials such as graphene are also relevant for spin caloritronics, thanks to efficient spin transport 9-11 , energy-dependent carrier mobility and unique density of states 12,13 . Here, we propose and demonstrate that a carrier thermal gradient in a graphene lateral spin valve can lead to a large increase of the spin voltage near to the graphene charge neutrality point. Such an increase results from a thermoelectric spin voltage, which is analogous to the voltage in a thermocouple and that can be enhanced by the presence of hot carriers generated by an applied current 14-17 . These results could prove crucial to drive graphene spintronic devices and, in particular, to sustain pure spin signals with thermal gradients and to tune the remote spin accumulation by varying the spin-injection bias.

  19. Low voltage electron beam accelerators

    International Nuclear Information System (INIS)

    Ochi, Masafumi

    2003-01-01

    Widely used electron accelerators in industries are the electron beams with acceleration voltage at 300 kV or less. The typical examples are shown on manufactures in Japan, equipment configuration, operation, determination of process parameters, and basic maintenance requirement of the electron beam processors. New electron beam processors with acceleration voltage around 100 kV were introduced maintaining the relatively high dose speed capability of around 10,000 kGy x mpm at production by ESI (Energy Science Inc. USA, Iwasaki Electric Group). The application field like printing and coating for packaging requires treating thickness of 30 micron or less. It does not require high voltage over 110 kV. Also recently developed is a miniature bulb type electron beam tube with energy less than 60 kV. The new application area for this new electron beam tube is being searched. The drive force of this technology to spread in the industries would be further development of new application, process and market as well as the price reduction of the equipment, upon which further acknowledgement and acceptance of the technology to societies and industries would entirely depend. (Y. Tanaka)

  20. Novel Interleaved Converter with Extra-High Voltage Gain to Process Low-Voltage Renewable-Energy Generation

    Directory of Open Access Journals (Sweden)

    Chih-Lung Shen

    2016-10-01

    Full Text Available This paper presents a novel interleaved converter (NIC with extra-high voltage gain to process the power of low-voltage renewable-energy generators such as photovoltaic (PV panel, wind turbine, and fuel cells. The NIC can boost a low input voltage to a much higher voltage level to inject renewable energy to DC bus for grid applications. Since the NIC has two circuit branches in parallel at frond end to share input current, it is suitable for high power applications. In addition, the NIC is controlled in an interleaving pattern, which has the advantages that the NIC has lower input current ripple, and the frequency of the ripple is twice the switching frequency. Two coupled inductors and two switched capacitors are incorporated to achieve a much higher voltage gain than conventional high step-up converters. The proposed NIC has intrinsic features such as leakage energy totally recycling and low voltage stress on power semiconductor. Thorough theoretical analysis and key parameter design are presented in this paper. A prototype is built for practical measurements to validate the proposed NIC.

  1. Distance protection of multiple-circuit shared tower transmission lines with different voltages

    DEFF Research Database (Denmark)

    Silva, Filipe Miguel Faria da; Bak, Claus Leth

    2017-01-01

    Multiple-circuit transmission lines combining different voltage levels in one tower present extra challenges when setting a protection philosophy, as faults between voltage levels are possible. This study presents a detailed theoretical analysis of such combined faults, including the development...

  2. Secondary Voltage Unbalance Compensation for Three-Phase Four-Wire Islanded Microgrids

    DEFF Research Database (Denmark)

    Tang, Fen; Zhou, Xiao; Meng, Lexuan

    2014-01-01

    This paper proposes a secondary voltage unbalance control approach that compensate voltage unbalances in three-phase four-wire islanded microgrid systems. It is implemented in the secondary control level of the microgrid hierarchical control structure. By sending information through low-bandwidth......This paper proposes a secondary voltage unbalance control approach that compensate voltage unbalances in three-phase four-wire islanded microgrid systems. It is implemented in the secondary control level of the microgrid hierarchical control structure. By sending information through low...

  3. Voltage control by tap-changing transformers for a radial distribution network

    Energy Technology Data Exchange (ETDEWEB)

    Salem, M.R.; Talat, L.A.; Soliman, H.M. [Omar Al-Mokhtar University, Al Bayda (Libya). Faculty of Engineering

    1997-11-01

    Voltage control is of interest to many researchers, and is currently being considered by many utilities for implementation in their energy control centres. Transformers with tap-changing facilities constitute an important means of controlling voltage throughout the system at all voltage levels. A new method for determining the minimal changes in transformer taps to control voltage levels is presented. The problem to be solved is cast into a nonlinear constraint optimisation. The constraints are tackled in the minimisation algorithm by forming the Lagrangian. Necessary conditions for optimality are derived and solved using the Newton-Raphson method. (author)

  4. Concept medium program

    DEFF Research Database (Denmark)

    Bjerrum, Peter

    2003-01-01

    The present essays is an attempt to dertermine the architecural project of the 21st century in realation to a modern conception of space as the medium of architecture, and of society as its program. This attempt adopts the internal point of view of an architect in describing a modern architectura...

  5. Radon in geological medium

    International Nuclear Information System (INIS)

    Hricko, J.

    1995-01-01

    The paper presented deals with behavior of the radon in geological medium and with some results of the radon survey in Bratislava and Kosice regions. 1) The a v has been detected in the holes 0.80 m deep. The density of observations - 3 reference areas (one represents 20 stations) per 1 km 2 . The radon risk maps in 1:25000 and 1:50000 scales have been compiled. The 56.8% of the project area lies in low radon risk, 37.6% in medium radon risk and 5.6% in high radon risk. Follow-up monitoring of the equivalent volume radon activity (EVRA) at the flats, located in the areas with high radon risk of the surface layer, has showed values several times higher than Slovak limits (Marianka, Raca, Vajnory). The evidence that neotectonic is excellent medium for rising up emanation to the subsurface layer, is shown on the map. The tectonic zone of Liscie udolie in Bratislava-Karlova Ves area has been clearly detected by profile radon survey (a v > 50 kBq/m 3 ). 2) At present, northern half of the area of Kosice in question was covered by radon survey. The low and medium radon risks have been observed here, while localities with high radon risk are small in extent. The part of radon risk and soil permeability map from northern Kosice area is shown. (J.K.) 3 figs., 2 refs

  6. Extension algorithm for generic low-voltage networks

    Science.gov (United States)

    Marwitz, S.; Olk, C.

    2018-02-01

    Distributed energy resources (DERs) are increasingly penetrating the energy system which is driven by climate and sustainability goals. These technologies are mostly connected to low- voltage electrical networks and change the demand and supply situation in these networks. This can cause critical network states. Network topologies vary significantly and depend on several conditions including geography, historical development, network design or number of network connections. In the past, only some of these aspects were taken into account when estimating the network investment needs for Germany on the low-voltage level. Typically, fixed network topologies are examined or a Monte Carlo approach is used to quantify the investment needs at this voltage level. Recent research has revealed that DERs differ substantially between rural, suburban and urban regions. The low-voltage network topologies have different design concepts in these regions, so that different network topologies have to be considered when assessing the need for network extensions and investments due to DERs. An extension algorithm is needed to calculate network extensions and investment needs for the different typologies of generic low-voltage networks. We therefore present a new algorithm, which is capable of calculating the extension for generic low-voltage networks of any given topology based on voltage range deviations and thermal overloads. The algorithm requires information about line and cable lengths, their topology and the network state only. We test the algorithm on a radial, a loop, and a heavily meshed network. Here we show that the algorithm functions for electrical networks with these topologies. We found that the algorithm is able to extend different networks efficiently by placing cables between network nodes. The main value of the algorithm is that it does not require any information about routes for additional cables or positions for additional substations when it comes to estimating

  7. Bootstrapped Low-Voltage Analog Switches

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper

    1999-01-01

    Novel low-voltage constant-impedance analog switch circuits are proposed. The switch element is a single MOSFET, and constant-impedance operation is obtained using simple circuits to adjust the gate and bulk voltages relative to the switched signal. Low-voltage (1-volt) operation is made feasible...

  8. Voltage Quality of Grid Connected Wind Turbines

    DEFF Research Database (Denmark)

    Chen, Zhe; Blaabjerg, Frede; Sun, Tao

    2004-01-01

    Grid connected wind turbines may cause quality problems, such as voltage variation and flicker. This paper discusses the voltage variation and flicker emission of grid connected wind turbines with doubly-fed induction generators. A method to compensate flicker by using a voltage source converter...

  9. 30 CFR 18.47 - Voltage limitation.

    Science.gov (United States)

    2010-07-01

    ... MINING PRODUCTS ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND ACCESSORIES Construction and Design Requirements... particular voltage(s) are provided in the design and construction of the equipment, its wiring, and... exceed 25 amperes. (3) All high voltage switch gear and control for equipment having a nameplate rating...

  10. Voltage generators of high voltage high power accelerators

    International Nuclear Information System (INIS)

    Svinin, M.P.

    1981-01-01

    High voltage electron accelerators are widely used in modern radiation installations for industrial purposes. In the near future further increasing of their power may be effected, which enables to raise the efficiency of the radiation processes known and to master new power-consuming production in industry. Improvement of HV generators by increasing their power and efficiency is one of many scientific and engineering aspects the successful solution of which provides further development of these accelerators and their technical parameters. The subject is discussed in detail. (author)

  11. Saliva as a diagnostic medium.

    Science.gov (United States)

    Pink, Richard; Simek, Jiri; Vondrakova, Jana; Faber, Edgar; Michl, Petr; Pazdera, Jindrich; Indrak, Karel

    2009-06-01

    This is a review of current knowledge on the use of saliva, gingival cervical fluid and mucosal transudate in the detection of some oral and systemic diseases as well as drugs. Oral fluid is a diagnostic medium that can be easily collected and with minimal invasion but it has been neglected in the past. Today, saliva is being used more often to diagnose: HIV virus, oro-facial and systemic tumors, cardiovascular disease and in detecting addictive substances. Neutropil levels in saliva may also indicate successful bone marrow transplant. Oral fluid is now systematically being researched and oral fluid analysis is being compared with the analysis of other diagnostic media such as blood and urine. A number of recent studies have focused on oncogenic marker detection and its monitoring in saliva. The latest clinical and laboratory findings on diagnostic markers of oropharyngeal carcinoma in oral fluid could be the beginning of their wider use as a diagnostic medium. Oral fluid can also be also used to diagnose other malignancies such as breast cancer which was one of the first malignant tumors to be detected using genetic protein biomarkers. Raised levels of CA15-3 and the epidermal growth factor (EGF) receptor have been found in patients with breast cancer and elevated levels of CA 125 and the glycoprotein complex in the saliva of ovarian cancer patients. Doubtless, the diagnostic value of saliva, aided by current technological development will increase rapidly in the near future.

  12. Isolated PWM DC-AC SICAM with an active capacitive voltage clamp[Pulse Density Modulated; Pulse Width Modulation

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.

    2004-03-15

    In this report an isolated PWM DC-AC SICAM with an active capacitive voltage clamp is presented. AC-DC power supply is implemented in its simplest form: diode rectifier followed by a medium-size charge-storage capacitors and possibly with an EMC filter on the mains entrance. Isolation from the AC mains is achieved using a high frequency (HF) transformer, whose voltages are not audio-modulated. The latter simplifies the design and is expected to have many advantages over the approach where the transformer voltages are modulated in regards to the audio signal reference. Input stage is built as a DC-AC inverter (push-pull, half-bridge or a full-bridge) and operated with 50% duty cycle, with all the challenges to avoid transformer saturation and obtain symmetrical operation. On the secondary side the output section is implemented as rectifier+inverter AC-AC stage, i.e. a true bidirectional bridge, which operation is aimed towards amplification of the audio signal. In order to solve the problem with the commutation of the load current, a dead time between the incoming and outgoing bidirectional switch is implemented, while a capacitive voltage clamp is used to keep the induced overvoltage to reasonable levels. The energy stored in the clamping capacitor is not wasted as in the dissipative clamps, but is rather transferred back to the primary side for further processing using an auxiliary isolated single-switch converter, i.e. an active clamping technique is used. (au)

  13. Medium-energy physics

    International Nuclear Information System (INIS)

    Anon.

    1980-01-01

    One of the basic challenges of medium-energy physics is the development of a clear picure of the manner in which pions propagate in nuclear matter. Since the pion is a basic quantum of the nuclear force, understanding its propagation in nuclei contributes to our understanding of the basic nature of nuclear forces. Key to such understanding is a comprehensive and precise experimental description of pion interactions both with complex nuclei and few nucleon systems. This is a major objective of the ANL effort in medium-energy physics. Experiments are carried out as a part of a comprehensive nuclear program, and, because of this perspective, the pion studies are expected to give new insights into the nature of nuclear forces. At the present time, almost all experimental activity is concentrated on measurements using various pion beams of the Los Alamos Meson Physics Facility

  14. Assessment of Voltage Stability Using Network Equivalent

    Directory of Open Access Journals (Sweden)

    Abhijit Chakrabarti

    2011-12-01

    Full Text Available In this paper a fast system voltage stability index (FSVSI has been proposed to assess overall system voltage stability of a multi-bus power system at a particular operating point using the concept of two bus network equivalent. A universal direct voltage stability index has also been explored to assess local (DVSI as well as overall system voltage stability (DSVSI. An index called system transmission quality factor (STQF has been developed to assess the power transmission quality of the overall system in the context of voltage stability. Two FACTS controllers, TCSC and STATCOM have also been incorporated in the present study to observe their effectiveness to ensure voltage stabilty. STATCOM has been found to be superior in order to improve voltage stability of power system as compared to TCSC. The developed concept has been validated using practical India Easten Grid (WBSEB system and it has a high potential of on-line application.

  15. Liquid chromatographic extraction medium

    Science.gov (United States)

    Horwitz, E. Philip; Dietz, Mark L.

    1994-01-01

    A method and apparatus for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column is described. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water.

  16. Manufacture of conical springs with elastic medium technology improvement

    Science.gov (United States)

    Kurguzov, S. A.; Mikhailova, U. V.; Kalugina, O. B.

    2018-01-01

    This article considers the manufacturing technology improvement by using an elastic medium in the stamping tool forming space to improve the conical springs performance characteristics and reduce the costs of their production. Estimation technique of disk spring operational properties is developed by mathematical modeling of the compression process during the operation of a spring. A technique for optimizing the design parameters of a conical spring is developed, which ensures a minimum voltage value when operated in the edge of the spring opening.

  17. Hadrons in the medium

    International Nuclear Information System (INIS)

    Leupold, Stefan

    2005-01-01

    QCD, the theory of the strong interaction, has a non-trivial vacuum structure. One way to characterize this structure is by means of non-vanishing matrix elements of quark or gluon operators, the condensates. In hot and/or dense enough strongly interacting media, QCD is subject to phase transitions or rapid crossovers. Consequently, the condensates typically change with density and temperature. An exciting aspect of hadron physics is the question how these changes affect the properties of hadrons which are put in a strongly interacting environment. Here vector mesons deserve special attention as they couple directly to (virtual) photons. The latter can decay into dileptons which leave the strongly interacting system untouched. Via that process information about possible in-medium modifications of the vector mesons can be carried to the detectors. With the ω-meson as an example I will review our current understanding of the connections between in-medium changes of condensates and the in-medium changes of the properties of hadrons. (author)

  18. Voltage Control of Distribution Grids with Multi-Microgrids Using Reactive Power Management

    Directory of Open Access Journals (Sweden)

    WLODARCZYK, P.

    2015-02-01

    Full Text Available Low-voltage Microgrids can be valuable sources of ancillary services for the Distribution System Operators (DSOs. The aim of this paper was to study if and how multi-microgrids can contribute to Voltage Control (VC in medium-voltage distribution grids by means of reactive power generation and/or absorption. The hierarchical control strategy was proposed with the main focus on the tertiary control which was defined as optimal power flow problem. The interior-point algorithm was applied to optimise experimental benchmark grid with the presence of Distributed Energy Resources (DERs. Moreover, two primary objectives were formulated: active power losses and amount of reactive power used to reach the voltage profile. As a result the active power losses were minimised to the high extent achieving the savings around 22% during entire day.

  19. Number-to-voltage converter on commutated condensers

    International Nuclear Information System (INIS)

    Grekhov, Yu.N.

    1975-01-01

    A code-voltage converter using precision voltage dividers based on commutated capacitors [1] is described which is distinguished by the absence of precision elements. Each digit includes eight field-effect transistors in two 1KT682 microcircuit assemblies and three microcapacitors with a conventional unstable capacitance 6200 pF +- 50%. The converter has a speed of response that is not inferior to that of converters based on R-2R matrices, while in time stability of the characteristics, low interference level, and low output impedance it is superior to such converters

  20. PC-based control of a high-voltage injector

    International Nuclear Information System (INIS)

    Constantin, F.

    1998-01-01

    The stability of high voltage injectors is one of the major problems in any accelerator system. Most of the troubles encountered in the normal operation of an accelerator are connected with the ion source and associated high voltage platforms, regardless of the source or high voltage generator type. The quality of the ion beam injected in the accelerator strongly depends on the power supplies used in the injector and on the ability to control the non-electrical parameters (gas-flow, temperature, etc.). A wide used method in controlling is based on optical links between high-voltage platform and computer, the adjustments being more or less automated. Although the method mentioned above can be still useful in injector control, a different approach is presented in this work, i.e., the computer itself is placed inside the high-voltage terminal. Only one optical link is still necessary to connect this computer with an user-friendly host at ground potential. Requirements: - varying and monitoring the filament current; - gas flow control in the ion source; - reading the vacuum values; - current and voltage control for the anodic, magnet, extraction, suppression and lens' sources. Even in the high voltage terminal there are compartments with different voltages regardless the floating ground. In our injector the extraction voltage is applied on the top of the ion source including the filament and the anodic voltage. The extraction voltage is of maximum 30 kV. In this situation a second optical link is required to transfer the control for the anodic and magnet source power supply assuming the dedicated computer on the floating ground. One PC is placed inside the high voltage terminal and one PC outside the injector. The optical link (more precisely two optical wires) connects the serial ports. The inside computer is equipped with two multipurpose ADC/DAC and digital I/O card. They permit to read or output DC levels ranging between 0 to 10 volts or TTL signals. The filament

  1. Precise derating of three phase induction motors with unbalanced voltages

    International Nuclear Information System (INIS)

    Faiz, Jawad; Ebrahimpour, H.

    2007-01-01

    Performance analysis of three phase induction motors under supply voltage unbalance conditions is normally conducted using the well-known symmetrical components analysis. In this analysis, the voltage unbalance level at the terminals of the machine is assessed by means of the NEMA or IEC definitions. Both definitions lead to a relatively large error in predicting the performance of a machine. A method has recently been proposed in which, in addition to the voltage unbalance factor (VUF), the phase angle has been taken into account in the analysis. This means that the voltage unbalance factor is regarded as a complex value. This paper shows that although the use of the complex VUF reduces the computational error considerably, it is still high. This is proven by evaluating the derating factor of a three phase induction motor. A method is introduced to determine the derating factor precisely using the complex unbalance factor for an induction motor operating under any unbalanced supply condition. A practical case for derating of a typical three phase squirrel cage induction motor supplied by an unbalanced voltage is studied in the paper

  2. Low voltage power supply for HCAL photodetectors in CMS

    CERN Document Server

    Kunov, B; Dimitrov, L

    2003-01-01

    The compact muon solenoid (CMS) is one of the detectors for the new large hadron collider (LHC) of CERN. Because of the high level magnetic field inside CMS specialized photodetectors - hybrid photo diodes (HPDs) are used in its hadron calorimeter (HCAL). For their normal operation HPDs need two supply voltages - one high voltage of about 10 kV and a bias voltage from 50 up to 200 V. Because of some specific requirements as very low output noise, very weak load current (10 mu A), high precision measurement of the load current etc., a new linear mode voltage stabilizer is used as bias voltage power supply. The base distinction of the device is that a current mirror is included in its input, providing a precise measurement of the load current without any electrical contact with the output line. This feature is very important because about 500 power supplies of this type are included in the total HPD power supply system of the HCAL subdetector and can not be local earthed. (3 refs).

  3. Development of Electromechanical Architectures for AC Voltage Metrology

    Directory of Open Access Journals (Sweden)

    Alexandre BOUNOUH

    2010-12-01

    Full Text Available This paper presents results of work undertaken for exploring MEMS capabilities to fabricate AC voltage references for electrical metrology and high precision instrumentation through the mechanical-electrical coupling in MEMS. From first MEMS test structures previously realized, a second set of devices with improved characteristics has been developed and fabricated with Silicon on Insulator (SOI Surface Micromachining process. These MEMS exhibit pull-in voltages of 5 V and 10 V to match with the best performance of the read-out electronics developed for driving the MEMS. Deep Level Transient Spectroscopy measurements carried out on the new design show resonance frequencies of about only some kHz, and the stability of the MEMS output voltage measured at 100 kHz has been found very promising for the best samples where the relative deviation from the mean value over almost 12 hours showed a standard deviation of about 6.3 ppm.

  4. The Application of Voltage Transformer Simulator in Electrical Test Training

    Science.gov (United States)

    Li, Nan; Zhang, Jun; Chai, Ziqi; Wang, Jingpeng; Yang, Baowei

    2018-02-01

    The voltage transformer test is an important means to monitor its operating state. The accuracy and reliability of the test data is directly related to the test skill level of the operator. However, the risk of test instruments damage, equipment being tested damage and electric shock in operator is caused by improper operation when training the transformer test. In this paper, a simulation device of voltage transformer is set up, and a simulation model is built for the most common 500kV capacitor voltage transformer (CVT), the simulation model can realize several test items of CVT by combing with teaching guidance platform, simulation instrument, complete set of system software and auxiliary equipment in Changchun. Many successful applications show that the simulation device has good practical value and wide application prospect.

  5. Impact of Distributed Generation on the Voltage Sag Performance of Transmission Systems

    Directory of Open Access Journals (Sweden)

    Pierluigi Caramia

    2017-07-01

    Full Text Available In this paper, we analysed the growing penetration of generating units from renewable energy sources in transmission power systems. Among the possible effects of the interaction of distributed generation (DG with transmission systems, we considered the abnormal operating conditions caused by short circuits in the transmission systems and the resulting voltage sags that occur in the network. A systematic method is presented for analysing the voltage sag behaviour of any transmission system in which large DG units are connected to the transmission system by means of High Voltage/Medium Voltage (HV/MV stations. The method proposed for obtaining the voltage sags is the fault position method (FPM, from which we derived a graphical visualization of the during-fault voltage (DFV matrix as a valuable tool to obtain an immediate measure of the propagation of voltage sags in the network. The results obtained were based on a portion of a real transmission system. The system that we considered is an actual portion of the Italian transmission system, and all of the quantities we used were obtained from the data of the Transmission system operator (TSO.

  6. Generic inertia emulation controller for multi-terminal voltage-source-converter high voltage direct current systems

    DEFF Research Database (Denmark)

    Zhu, Jiebei; Guerrero, Josep M.; Hung, William

    2014-01-01

    to contribute an inertial response to connected AC systems during system disturbances, in a fashion similar to synchronous generators. The DC link capacitors within the MTDC are utilised by the INEC scheme to exchange stored energy with the AC system by varying the overall DC voltage level of the MTDC network...

  7. Power conditioning using dynamic voltage restorers under different voltage sag types

    Directory of Open Access Journals (Sweden)

    Ahmed M. Saeed

    2016-01-01

    Full Text Available Voltage sags can be symmetrical or unsymmetrical depending on the causes of the sag. At the present time, one of the most common procedures for mitigating voltage sags is by the use of dynamic voltage restorers (DVRs. By definition, a DVR is a controlled voltage source inserted between the network and a sensitive load through a booster transformer injecting voltage into the network in order to correct any disturbance affecting a sensitive load voltage. In this paper, modelling of DVR for voltage correction using MatLab software is presented. The performance of the device under different voltage sag types is described, where the voltage sag types are introduced using the different types of short-circuit faults included in the environment of the MatLab/Simulink package. The robustness of the proposed device is evaluated using the common voltage sag indices, while taking into account voltage and current unbalance percentages, where maintaining the total harmonic distortion percentage of the load voltage within a specified range is desired. Finally, several simulation results are shown in order to highlight that the DVR is capable of effective correction of the voltage sag while minimizing the grid voltage unbalance and distortion, regardless of the fault type.

  8. Effects of Electrode Material on the Voltage of a Tree-Based Energy Generator.

    Directory of Open Access Journals (Sweden)

    Zhibin Hao

    Full Text Available The voltage between a standing tree and its surrounding soil is regarded as an innovative renewable energy source. This source is expected to provide a new power generation system for the low-power electrical equipment used in forestry. However, the voltage is weak, which has caused great difficulty in application. Consequently, the development of a method to increase the voltage is a key issue that must be addressed in this area of applied research. As the front-end component for energy harvesting, a metal electrode has a material effect on the level and stability of the voltage obtained. This study aimed to preliminarily ascertain the rules and mechanisms that underlie the effects of electrode material on voltage. Electrodes of different materials were used to measure the tree-source voltage, and the data were employed in a comparative analysis. The results indicate that the conductivity of the metal electrode significantly affects the contact resistance of the electrode-soil and electrode-trunk contact surfaces, thereby influencing the voltage level. The metal reactivity of the electrode has no significant effect on the voltage. However, passivation of the electrode materials markedly reduces the voltage. Suitable electrode materials are demonstrated and recommended.

  9. Spiegel. Medium. Kunst

    DEFF Research Database (Denmark)

    Kacunko, Slavko

    to human talent, came the millennia of untiring labours and the play of art and science and thought. The human love-affair with reflection (to cite Mark Pendergast’s subtitle - Mirror/Mirror: A History of the Human Love Affair with Reflection [New York 2003]) has always been a platonic one and I hold...... and cultural perspective. From 1800 on, the great incentive was to push forward the material-physical and optical-mechanical and especially the media ‘exploitation’ of the mirror. The significance of the mirror as a central meta-medium of the visual emerged in a particularly striking way in the late 1830s...

  10. Ozon Generation During High Voltage Leak Detection. Fiction or Reality?

    Science.gov (United States)

    Becker, Sophie; Bickert, Dr Volker; Reimers, Kai; Becker, Dr Martin

    2018-02-14

    In order to further clarify if and how much Ozone is generated during HVLD and to identify measures to reduce the impact of Ozone generation on product quality a highly sensitive analytical system [4] was employed to investigate the generation of Ozone at different operational conditions of HVLD integrity testing. The analytical system is based on oxidation of Iodide ions in solution and identification of the Iodine formed by N, N-Diethyl-p-phenylendiamine (DPD) according to DIN 38403 [4].Sensitivity of the system was found suitable to detect Ozone levels as low as 0.025 ppm (mg/l). HVLD process parameters inspection speed, high voltage, filling level of the ampoule and exposure time to the ampoule to high voltage were varied between maximum and minimum values ap-plicable in integrity testing of different ampoule sizes. For variation of exposure time ampoules were repetitively tested by the leak testing machine to acchive a maximum exposure time of the ampoule up to 24 sec (exposure time during production detected during the study under all inspection conditions. Even repeated exposure of the ampoules to high voltage leak detection did not result in generation of measurable Ozone levels. It has to be concluded that high voltage leak detection is not prone to cause oxidation of the drug products. Copyright © 2018, Parenteral Drug Association.

  11. Electronics drivers for high voltage dielectric electro active polymer (DEAP) applications

    DEFF Research Database (Denmark)

    Zhang, Zhe; Andersen, Michael A. E.

    2015-01-01

    ), but the voltage balancing across the series - connected high voltage IGBTs is a critical issue and accordi ngly a novel gate driver circuitry is proposed and equipped; due to the requirements of the audio products, such as low distortion and noise, the multi - level Buck converter based Class - D amplifier...

  12. Analog IC techniques for low-voltage low-power electronics

    NARCIS (Netherlands)

    Serdijn, W.A.; Verhoeven, C.J.M.; Van Roermund, A.H.M.

    1995-01-01

    Analog IC Techniques lor Low-Voltage Low Power Electronics addresses many very important, but recent, techniques which enable electronics to operate at a low supply voltage and consume a minimum amount of power. Apart from investigations at the device, circuit and system levels, the book provides a

  13. Phase diagrams and switching of voltage and magnetic field in dilute magnetic semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Escobedo, R. [Departamento de Matematica Aplicada y Ciencias de la Computacion, Universidad de Cantabria, 39005 Santander (Spain); Carretero, M.; Bonilla, L.L. [G. Millan Institute, Fluid Dynamics, Nanoscience and Industrial Maths., Universidad Carlos III de Madrid, 28911 Leganes (Spain); Unidad Asociada al Instituto de Ciencia de Materiales, CSIC, 28049 Cantoblanco, Madrid (Spain); Platero, G. [Instituto de Ciencia de Materiales, CSIC, 28049 Cantoblanco, Madrid (Spain)

    2010-04-15

    The response of an n-doped dc voltage biased II-VI multi-quantum well dilute magnetic semiconductor nanostructure having its first well doped with magnetic (Mn) impurities is analyzed by sweeping wide ranges of both the voltage and the Zeeman level splitting induced by an external magnetic field. The level splitting versus voltage phase diagram shows regions of stable self-sustained current oscillations immersed in a region of stable stationary states. Transitions between stationary states and self-sustained current oscillations are systematically analyzed by both voltage and level splitting abrupt switching. Sudden voltage or/and magnetic field changes may switch on current oscillations from an initial stationary state, and reciprocally, current oscillations may disappear after sudden changes of voltage or/and magnetic field changes into the stable stationary states region. The results show how to design such a device to operate as a spin injector and a spin oscillator by tuning the Zeeman splitting (through the applied external magnetic field), the applied voltage and the sample configuration parameters (doping density, barrier and well widths, etc.) to select the desired stationary or oscillatory behavior. Phase diagram of Zeeman level splitting {delta} vs. dimensionless applied voltage {phi} for N = 10 QWs. White region: stable stationary states; black: stable self-sustained current oscillations. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Empirical Verification of Fault Models for FPGAs Operating in the Subcritical Voltage Region

    DEFF Research Database (Denmark)

    Birklykke, Alex Aaen; Koch, Peter; Prasad, Ramjee

    2013-01-01

    We present a rigorous empirical study of the bit-level error behavior of field programmable gate arrays operating in the subcricital voltage region. This region is of significant interest as voltage-scaling under normal circumstances is halted by the first occurrence of errors. However, accurate...

  15. Development of modulation strategies for NPC converter addressing DC link voltage balancing and CMV reduction

    DEFF Research Database (Denmark)

    Boian, D.; Biris, C.; Teodorescu, Remus

    2012-01-01

    3L-NPC inverters are more popular due to their superior performance compared with two level inverters. One of the most optimal applications for multilevel inverter is the Adjustable Speed Drives (ASD). The industry reported numerous ASD failures due to high frequency PWM. Those failures consist...... strategies is to reduce the Common Mode Voltage (CMV) and balance the DC Link Voltage....

  16. High voltage load resistor array

    Science.gov (United States)

    Lehmann, Monty Ray [Smithfield, VA

    2005-01-18

    A high voltage resistor comprising an array of a plurality of parallel electrically connected resistor elements each containing a resistive solution, attached at each end thereof to an end plate, and about the circumference of each of the end plates, a corona reduction ring. Each of the resistor elements comprises an insulating tube having an electrode inserted into each end thereof and held in position by one or more hose clamps about the outer periphery of the insulating tube. According to a preferred embodiment, the electrode is fabricated from stainless steel and has a mushroom shape at one end, that inserted into the tube, and a flat end for engagement with the end plates that provides connection of the resistor array and with a load.

  17. Voltage-Controlled Floating Resistor Using DDCC

    Directory of Open Access Journals (Sweden)

    M. Kumngern

    2011-04-01

    Full Text Available This paper presents a new simple configuration to realize the voltage-controlled floating resistor, which is suitable for integrated circuit implementation. The proposed resistor is composed of three main components: MOS transistor operating in the non-saturation region, DDCC, and MOS voltage divider. The MOS transistor operating in the non-saturation region is used to configure a floating linear resistor. The DDCC and the MOS transistor voltage divider are used for canceling the nonlinear component term of MOS transistor in the non-saturation region to obtain a linear current/voltage relationship. The DDCC is employed to provide a simple summer of the circuit. This circuit offers an ease for realizing the voltage divider circuit and the temperature effect that includes in term of threshold voltage can be compensated. The proposed configuration employs only 16 MOS transistors. The performances of the proposed circuit are simulated with PSPICE to confirm the presented theory.

  18. Theoretical analysis of magnetic sensor output voltage

    International Nuclear Information System (INIS)

    Liu Haishun; Dun Chaochao; Dou Linming; Yang Weiming

    2011-01-01

    The output voltage is an important parameter to determine the stress state in magnetic stress measurement, the relationship between the output voltage and the difference in the principal stresses was investigated by a comprehensive application of magnetic circuit theory, magnetization theory, stress analysis as well as the law of electromagnetic induction, and a corresponding quantitative equation was derived. It is drawn that the output voltage is proportional to the difference in the principal stresses, and related to the angle between the principal stress and the direction of the sensor. This investigation provides a theoretical basis for the principle stresses measurement by output voltage. - Research highlights: → A comprehensive investigation of magnetic stress signal. → Derived a quantitative equation about output voltage and the principal stresses. → The output voltage is proportional to the difference of the principal stresses. → Provide a theoretical basis for the principle stresses measurement.

  19. DENSE MEDIUM CYCLONE OPTIMIZATON

    Energy Technology Data Exchange (ETDEWEB)

    Gerald H. Luttrell; Chris J. Barbee; Peter J. Bethell; Chris J. Wood

    2005-06-30

    Dense medium cyclones (DMCs) are known to be efficient, high-tonnage devices suitable for upgrading particles in the 50 to 0.5 mm size range. This versatile separator, which uses centrifugal forces to enhance the separation of fine particles that cannot be upgraded in static dense medium separators, can be found in most modern coal plants and in a variety of mineral plants treating iron ore, dolomite, diamonds, potash and lead-zinc ores. Due to the high tonnage, a small increase in DMC efficiency can have a large impact on plant profitability. Unfortunately, the knowledge base required to properly design and operate DMCs has been seriously eroded during the past several decades. In an attempt to correct this problem, a set of engineering tools have been developed to allow producers to improve the efficiency of their DMC circuits. These tools include (1) low-cost density tracers that can be used by plant operators to rapidly assess DMC performance, (2) mathematical process models that can be used to predict the influence of changes in operating and design variables on DMC performance, and (3) an expert advisor system that provides plant operators with a user-friendly interface for evaluating, optimizing and trouble-shooting DMC circuits. The field data required to develop these tools was collected by conducting detailed sampling and evaluation programs at several industrial plant sites. These data were used to demonstrate the technical, economic and environmental benefits that can be realized through the application of these engineering tools.

  20. Reactive Power Control for Voltage Management

    OpenAIRE

    Hasan, MD. Shakib

    2017-01-01

    This thesis presents methods for voltage management in distribution systems with high photovoltaic (PV) power production. The high PV penetration leads to both new challenges such as voltage profile violation and reverse power flow, and also new opportunities. Traditionally, the voltage control in the distribution network is achieved by common devices in the networks such as capacitor banks, static synchronous compensators (STATCOMs) and on-load tap changers (OLTCs). This thesis has considere...

  1. Unsaturated medium hydrocarbons pollution evaluation

    International Nuclear Information System (INIS)

    Di Luise, G.

    1991-01-01

    When the so called porous unsaturated medium, that's the vertical subsoil section between both the ground and water-table level, is interested by a hydrocarbons spill, the problem to evaluate the pollution becomes difficult: considering, essentially, the natural coexistence in it of two fluids, air and water, and the interactions between them. This paper reports that the problems tend to increase when a third fluid, the pollutant, immiscible with water, is introduced into the medium: a three-phases flow, which presents several analogies with the flow conditions present in an oil-reservoir, will be established. In such a situation, it would be very useful to handle the matter by the commonly used parameters in the oil reservoirs studies such as: residual saturation, relative permeability, phases mobility, to derive a first semiquantitative estimation of the pollution. The subsoil pollution form hydrocarbons agents is one of the worldwide more diffused causes of contamination: such events are generally referable to two main effects: accidental (oil pipeline breakdowns, e.g.), and continuous (underground tanks breaks, industrial plants leakages, e.g.)

  2. Low-Voltage Switched-Capacitor Circuits

    DEFF Research Database (Denmark)

    Bidari, E.; Keskin, M.; Maloberti, F.

    1999-01-01

    Switched-capacitor stages are described which can function with very low (typically 1 V) supply voltages, without using voltage boosting or switched op-amps. Simulations indicate that high performance may be achieved using these circuits in filter or data converter applications.......Switched-capacitor stages are described which can function with very low (typically 1 V) supply voltages, without using voltage boosting or switched op-amps. Simulations indicate that high performance may be achieved using these circuits in filter or data converter applications....

  3. Impact of wind turbine control strategies on voltage performance

    OpenAIRE

    Vittal, Eknath; O'Malley, Mark; Keane, Andrew

    2009-01-01

    This study examines the 2013 Irish electricity network and its ability to accommodate large levels of wind generation while maintaining appropriate voltage levels across the system. The network provides a fully functional test system that is suitable for large scale power flow and dynamic simulations. In the next decade, wind generation is expected to constitute large percentage of the country’s new renewable generation portfolio due to the rich wind resource available in...

  4. Excitation of voltage oscillations in an induction voltage adder

    Directory of Open Access Journals (Sweden)

    Nichelle Bruner

    2009-07-01

    Full Text Available The induction voltage adder is an accelerator architecture used in recent designs of pulsed-power driven x-ray radiographic systems such as Sandia National Laboratories’ Radiographic Integrated Test Stand (RITS, the Atomic Weapons Establishment’s planned Hydrus Facility, and the Naval Research Laboratory’s Mercury. Each of these designs relies on magnetic insulation to prevent electron loss across the anode-cathode gap in the vicinity of the adder as well as in the coaxial transmission line. Particle-in-cell simulations of the RITS adder and transmission line show that, as magnetic insulation is being established during a pulse, some electron loss occurs across the gap. Sufficient delay in the cavity pulse timings provides an opportunity for high-momentum electrons to deeply penetrate the cavities of the adder cells where they can excite radio-frequency resonances. These oscillations may be amplified in subsequent gaps, resulting in oscillations in the output power. The specific modes supported by the RITS-6 accelerator and details of the mechanism by which they are excited are presented in this paper.

  5. Design and Construction of a Test Bench to Characterize Efficiency and Reliability of High Voltage Battery Energy Storage Systems

    DEFF Research Database (Denmark)

    Blank, Tobias; Thomas, Stephan; Roggendorf, Christoph

    2010-01-01

    system efficiency. High voltage batteries may be advantageous for future medium voltage DC-grids as well. In all cases, high availability and reliability is indispensable. Investigations on the operating behavior of such systems are needed. For this purpose, a test bench for high voltage storage systems...... was built to analyze these processes for different battery technologies. A special safety infrastructure for the test bench was developed due to the high voltage and the storable energy of approximately 120 kWh. This paper presents the layout of the test bench for analyzing high voltage batteries with about...... 4,300 volts including all components, the safety requirements with the resultant safety circuit and the aim of the investigations to be performed with the test bench....

  6. SYNTHESIS OF VOLTAGES OF UNIFORM PWM IN TIME REGULATION

    Directory of Open Access Journals (Sweden)

    A. G. Stryzhniou

    2014-01-01

    Full Text Available The article describes a process of synthesis and qualitative assessment of the harmonic composition of voltages of multiple and single PWM pulses in time regulation, being, along with amplitude, frequency and phase method, one of control methods of an asynchronous motor. The main point of time regulation is that a pause after any two single PWM pulses with different polarity or after any two groups of multiple PWM pulses with different polarity changes during a process of regulation. Feature of time regulation is that a motor has fast response in the range of small-signal of control and good linearity of speed-torque characteristics in the whole control range. Analytical expressions of parameters of PWM pulses ai and ti are obtained which allow to simplify considerably a process of formation and implementation of time regulation using tabular or indexed-tabular methods. These expressions allow not only to define voltage amplitude of  harmonic but also to perform qualitative assessment of harmonic composition of output voltages at time regulation. It is specified that harmonic frequencies wi = w0/q change in inverse proportion to magnitude of parameter q during a process of regulation and there is a replacement of a fundamental frequency by frequencies of higher harmonics.The offered approach allows to synthesize voltage of uniform single and multiple PWM pulses and to perform their comparative and qualitative analysis and the obtained expressions can be used at modeling of AC motor work. Voltage of multiple PWM pulses which is formed using stepped reference voltage with even quantity of steps in a half period and a pause on a zero level has the best parameters by criterion of a minimum of harmonic components and a maximum of a factor of anharmonicity Kнс at time regulation.

  7. Index-Based Assessment of Voltage Rise and Reverse Power Flow Phenomena in a Distribution Feeder Under High PV Penetration

    DEFF Research Database (Denmark)

    Hasheminamin, Maryam; Agelidis, Vassilios G.; Salehi, Vahid

    2015-01-01

    -based methodology for assessing the impact of high solar PV generation, considering the reverse power flow and voltage rise phenomena. Indices are defined that link these two phenomena and their impact on the voltage profile across the feeder. This assessment relies on detailed modeling of the network and the solar......The proliferation of photovoltaic (PV) generation in low- and medium-voltage distribution networks is expected to continue. Qualified studies can quantify adverse impacts of high PV penetration on distribution networks and assist utilities in decision making. This paper proposes an index...

  8. Diffusion voltage in polymer light emitting diodes measured with electric field induced second harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Kristensen, P.K.; Rafaelsen, J.; Pedersen, T.G.; Pedersen, K. [Department of Physics and Nanotechnology, Aalborg University, Pontoppidanstraede 103, 9220 Aalborg East (Denmark)

    2005-12-01

    We apply electric field induced second harmonic (EFISH) to polymer light emitting diodes (PLEDs) and demonstrate the ability to determine the diffusion voltage in PLED devices. The EFISH signal is proportional to the square of the effective field, which is the sum of the diffusion voltage and the applied voltage. By minimizing the EFISH-signal as a function of the applied voltage, the diffusion voltage is determined by measuring the applied voltage that cancels out the diffusion voltage. The PLEDs are fabricated with indium tin oxide (ITO) as the hole injecting contact and two different electron injecting contacts, namely aluminum and calcium. The diffusion voltage originates from the rearranged charges caused by the difference in Fermi levels in the materials in the PLEDs. Different contacts will thus cause different diffusion voltages. We demonstrate here that the EFISH signal is proportional to the square of the effective field in both reverse and forward bias, and discuss the dependence on contact materials. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Vacuum circuit breaker modelling for the assessment of transient recovery voltages: application to various network configurations

    DEFF Research Database (Denmark)

    Bak, Claus Leth; Borghetti, Alberto; Glasdam, Jakob Bærholm

    2018-01-01

    Vacuum circuit breakers (VCBs) are widely used for medium voltage applications when low maintenance, long operating life, and large number of allowable switching cycles are required. The accurate estimation of the transient recovery voltages (TRVs) associated with their manoeuvres is indispensable...... capabilities of simulating TRVs due to opening/closing manoeuvres, namely the switching of large electrical motors and the switching of cables collecting offshore wind farms (OWFs). Data from digital fault recorder (DFR) in a water-pumping plant and from a measurement campaign in an OWF using a high...

  10. Voltage Unbalance Compensation with Smart Three-phase Loads

    DEFF Research Database (Denmark)

    Douglass, Philip; Trintis, Ionut; Munk-Nielsen, Stig

    2016-01-01

    This paper describes the design, proof-of-concept simulations and laboratory test of an algorithm for controlling active front-end rectifiers to reduce voltage unbalance. Using inputs of RMS voltage, the rectifier controller allocates load unevenly on its 3 phases to compensate for voltage...... are evaluated: one metric based on the maximum deviation of RMS phaseneutral voltage from the average voltage and one metric based on negative sequence voltage. The tests show that controller that uses phase-neutral voltage as input can in most cases eliminate the deviations of phase voltage from the average...... voltage, but it does not reduce the negative sequence voltage. The controller that uses phase-phase voltage as input eliminates negative sequence voltage, and reduces voltage deviations from the average to approximately half their initial value. Current unbalance is reduced when the voltage unbalance...

  11. Voltage-Sensitive Load Controllers for Voltage Regulation and Increased Load Factor in Distribution Systems

    DEFF Research Database (Denmark)

    Douglass, Philip James; Garcia-Valle, Rodrigo; Østergaard, Jacob

    2014-01-01

    This paper presents a novel controller design for controlling appliances based on local measurements of voltage. The controller finds the normalized voltage deviation accounting for the sensitivity of voltage measurements to appliance state. The controller produces a signal indicating desired pow...

  12. Grid Voltage Modulated Control of Grid-Connected Voltage Source Inverters under Unbalanced Grid Conditions

    DEFF Research Database (Denmark)

    Li, Mingshen; Gui, Yonghao; Quintero, Juan Carlos Vasquez

    2017-01-01

    In this paper, an improved grid voltage modulated control (GVM) with power compensation is proposed for grid-connected voltage inverters when the grid voltage is unbalanced. The objective of the proposed control is to remove the power ripple and to improve current quality. Three power compensation...

  13. Pre-breakdown and Breakdown Mechanisms of an Inhibited Gas to Liquid Hydrocarbon Transformer Oil under Negative Lightning Impulse Voltage

    OpenAIRE

    Lu, Wu; Liu, Qian; Wang, Z.D

    2017-01-01

    In this paper, streamer and breakdown phenomena and their mechanisms of an inhibited Gas-To-Liquid (GTL) transformer oil under standard negative lightning impulse voltages were studied. A conventional inhibited mineral oil was also tested as the benchmark. Experiments were carried out in 25 mm and 50 mm point-plane gaps. Streamer and breakdown phenomena of both oils were observed from the streamer inception voltage level up to the voltage level at which fast streamer appears with velocity ove...

  14. High-voltage engineering and testing

    CERN Document Server

    Ryan, Hugh M

    2013-01-01

    This 3rd edition of High Voltage Engineering Testing describes strategic developments in the field and reflects on how they can best be managed. All the key components of high voltage and distribution systems are covered including electric power networks, UHV and HV. Distribution systems including HVDC and power electronic systems are also considered.

  15. Low-Voltage Switched-Capacitor Circuits

    DEFF Research Database (Denmark)

    Bidari, E.; Keskin, M.; Maloberti, F.

    1999-01-01

    Switched-capacitor stages are described which can function with very low (typically 1 V) supply voltages, without using voltage boosting or switched op-amps. Simulations indicate that high performance may be achieved using these circuits in filter or data converter applications....

  16. Reduced Voltage Scaling in Clock Distribution Networks

    Directory of Open Access Journals (Sweden)

    Khader Mohammad

    2009-01-01

    Full Text Available We propose a novel circuit technique to generate a reduced voltage swing (RVS signals for active power reduction on main buses and clocks. This is achieved without performance degradation, without extra power supply requirement, and with minimum area overhead. The technique stops the discharge path on the net that is swinging low at a certain voltage value. It reduces active power on the target net by as much as 33% compared to traditional full swing signaling. The logic 0 voltage value is programmable through control bits. If desired, the reduced-swing mode can also be disabled. The approach assumes that the logic 0 voltage value is always less than the threshold voltage of the nMOS receivers, which eliminate the need of the low to high voltage translation. The reduced noise margin and the increased leakage on the receiver transistors using this approach have been addressed through the selective usage of multithreshold voltage (MTV devices and the programmability of the low voltage value.

  17. Technical feasibility study of Voltage Optimization Unit

    DEFF Research Database (Denmark)

    Hu, Junjie; Marinelli, Mattia; Coppo, Massimiliano

    are used as load basics for the analysis. In term of PV genera-tion profiles, a realistic PV output power is assumed. Four relevant indicies such as phase neutral voltage, netural potential voltage, unbalanced factor (VUF), and power losses are evaluated in the present study. The simulation tests include...

  18. Voltage-gated lipid ion channels

    DEFF Research Database (Denmark)

    Blicher, Andreas; Heimburg, Thomas Rainer

    2013-01-01

    probability as a function of voltage. The voltage-dependence of the lipid pores is found comparable to that of protein channels. Lifetime distributions of open and closed events indicate that the channel open distribution does not follow exponential statistics but rather power law behavior for long open times...

  19. Low-Voltage Continuous Electrospinning Patterning.

    Science.gov (United States)

    Li, Xia; Li, Zhaoying; Wang, Liyun; Ma, Guokun; Meng, Fanlong; Pritchard, Robyn H; Gill, Elisabeth L; Liu, Ye; Huang, Yan Yan Shery

    2016-11-30

    Electrospinning is a versatile technique for the construction of microfibrous and nanofibrous structures with considerable potential in applications ranging from textile manufacturing to tissue engineering scaffolds. In the simplest form, electrospinning uses a high voltage of tens of thousands volts to draw out ultrafine polymer fibers over a large distance. However, the high voltage limits the flexible combination of material selection, deposition substrate, and control of patterns. Prior studies show that by performing electrospinning with a well-defined "near-field" condition, the operation voltage can be decreased to the kilovolt range, and further enable more precise patterning of fibril structures on a planar surface. In this work, by using solution dependent "initiators", we demonstrate a further lowering of voltage with an ultralow voltage continuous electrospinning patterning (LEP) technique, which reduces the applied voltage threshold to as low as 50 V, simultaneously permitting direct fiber patterning. The versatility of LEP is shown using a wide range of combination of polymer and solvent systems for thermoplastics and biopolymers. Novel functionalities are also incorporated when a low voltage mode is used in place of a high voltage mode, such as direct printing of living bacteria; the construction of suspended single fibers and membrane networks. The LEP technique reported here should open up new avenues in the patterning of bioelements and free-form nano- to microscale fibrous structures.

  20. The LMF triaxial MITL voltage adder system

    International Nuclear Information System (INIS)

    Mazarakis, M.G.; Smith, D.L.; Bennett, L.F.; Lockner, T.R.; Olson, R.E.; Poukey, J.W.

    1992-01-01

    The light-ion microfusion driver design consists of multiple accelerating modules fired in coincidence and sequentially in order to provide the desired ion energy, power pulse shape and energy deposition uniformity on an Inertial Confinement Fusion (ICF) target. The basic energy source is a number of Marx generators which, through the appropriate pulse power conditioning, provide the necessary voltage pulse wave form to the accelerating gaps or feeds of each module. The cavity gaps are inductively isolated, and the voltage addition occurs in the center conductor of the voltage adder which is the positive electrode while the electrons of the sheath flow closer to the outer cylinder which is the magnetically insulated cathode electrode. Each module powers a separate two-stage extraction diode which provides a low divergence ion beam. In order to provide the two separate voltage pulses required by the diode, a triaxial adder system is designed for each module. The voltage addition occurs in two separate MITLs. The center hollow cylinder (anode) of the second MITL also serves as the outer cathode electrode for the extension of the first voltage adder MITL. The voltage of the second stage is about twice that of the first stage. The cavities are connected in series to form the outer cylinder of each module. The accelerating modules are positioned radially in a symmetrical way around the fusion chamber. A preliminary conceptual design of the LMF modules with emphasis on the voltage adders and extension MITLs will be presented and discussed

  1. Design and Control of Parallel Three Phase Voltage Source Inverters in Low Voltage AC Microgrid

    Directory of Open Access Journals (Sweden)

    El Hassane Margoum

    2017-01-01

    Full Text Available Design and hierarchical control of three phase parallel Voltage Source Inverters are developed in this paper. The control scheme is based on synchronous reference frame and consists of primary and secondary control levels. The primary control consists of the droop control and the virtual output impedance loops. This control level is designed to share the active and reactive power correctly between the connected VSIs in order to avoid the undesired circulating current and overload of the connected VSIs. The secondary control is designed to clear the magnitude and the frequency deviations caused by the primary control. The control structure is validated through dynamics simulations.The obtained results demonstrate the effectiveness of the control structure.

  2. Inhomogeneity effects in HTS coated conductors used as resistive FCLs in medium voltage grids

    Science.gov (United States)

    Colangelo, Daniele; Dutoit, Bertrand

    2012-09-01

    For resistive fault current limiters (RFCLs) based on high temperature superconducting coated conductors (HTS-CCs), inhomogeneity, in terms of critical current and geometrical imperfections such as stabilizer and substrate thicknesses, plays a very important role and it may limit the penetration of such devices into the electrical market. This paper presents an electrothermal model, developed in SimPowerSystem™, able to describe the transient response of HTS-CC candidates with different degrees of inhomogeneity, both in terms of critical current and of stabilizer thickness. Critical current inhomogeneity has been modeled with Gaussian distributions. The layer thicknesses used in the simulations have been chosen by fitting the temperature dependence of real tape resistances. Our approach considers relative inhomogeneity positions as well as thermal conduction along the HTS-CC length. The model is tuned using experimental measurements made on ReBaCuO coated conductors. A new dynamical thermal calibration of the model is proposed using finite element method calculations. Inhomegeneity effects with different possible faults (e.g. three phase and single phase short-circuit) are presented.

  3. Potentially damaging failure modes of high- and medium-voltage electrical equipment

    International Nuclear Information System (INIS)

    Hoy, H.C.

    1983-07-01

    The electrical equipment failures of both nuclear and nonnuclear public utilities were reviewed. Those failures that could pose an additional problem to surrounding and connected equipment were defined. The literature was searched; utilities, repair shops, and large electrical equipment users were contacted for failure information. The data were reviewed in detail, and failure modes were determined. Sample cascade failures are discussed. The failure rate of electrical equipment in utilities is historically quite low. Nuclear plants record too few failures to be statistically valid, but failures that have been recorded show that good design usually restricts the failure to a single piece of equipment

  4. Instrument electronic transformers for medium voltage systems; Transformadores eletronicos de instrumentos para sistemas de media tensao

    Energy Technology Data Exchange (ETDEWEB)

    Javora, Radek; Stefanka, Martin; Mahonen, Pentti; Niemi, Tapio; Rintamaki, Olli [ABB, Helsinki (Finland); ABB, Prague (Czech Republic)

    2010-02-15

    This paper compares the conventional technologies and the electronic of instrument transformers, and highlights the advantages, discoveries and principles of electronic models. Such equipment are essentially indicated for using with as micro processed relays at the substations, and also projected for connection to the IEDs, and the future digital communication (author)

  5. Non destructive testing of medium and high voltage cables with a transportable radiography system

    Directory of Open Access Journals (Sweden)

    D. V. Bandekas

    2010-01-01

    Full Text Available A power cable is the most important part in a power transmission system. The cables must be total quality dedicated andcertified for development, manufacturing and installation, however are exposed to a corrosive environment. The purpose ofthis paper is to show that the fast neutron radiography with a transportable system is a solution to find defects in the cablesand reduce the cost of inspection. The design, regarding the materials considered, was compatible with the European UnionDirective on “Restriction of Hazardous Substances” (RoHS 2002/95/EC, hence excluding the use of cadmium and lead.Wide width values for the collimator ratio were calculated. With suitable collimator design it was possibly to optimize theneutron radiography parameters. Finally the shielding design was examined closely. The proposed system has been simulatedusing the MCNPX code.

  6. Knowledge extraction from medium voltage load diagrams to support the definition of electrical tariffs

    OpenAIRE

    Ramos, Sérgio; Figueiredo, Vera; Rodrigues, Fátima; Pinheiro, Raul; Vale, Zita

    2007-01-01

    With the electricity market liberalization, distribution and retail companies are looking for better market strategies based on adequate information upon the consumption patterns of its electricity customers. In this environment all consumers are free to choose their electricity supplier. A fair insight on the customer´s behaviour will permit the definition of specific contract aspects based on the different consumption patterns. In this paper Data Mining (DM) techniques are applied to electr...

  7. A high speed, medium voltage pulse amplifier for diode reverse transient measurements

    Science.gov (United States)

    Chudobiak, Michael J.

    1995-11-01

    A dc-coupled nonlinear pulse amplifier circuit is presented. The circuit presented can produce 40 V peak-to-peak pulses with 3 ns rise and fall times. This speed is obtained by using class D transistor amplifier stages. This circuit is shown to be useful for measuring the reverse recovery transients of fast switching diodes such as the 1N4148, and fast recovery power rectifiers.

  8. A Smoothing Technique for the Multifractal Analysis of a Medium Voltage Feeders Electric Current

    Science.gov (United States)

    de Santis, Enrico; Sadeghian, Alireza; Rizzi, Antonello

    2017-12-01

    The current paper presents a data-driven detrending technique allowing to smooth complex sinusoidal trends from a real-world electric load time series before applying the Detrended Multifractal Fluctuation Analysis (MFDFA). The algorithm we call Smoothed Sort and Cut Fourier Detrending (SSC-FD) is based on a suitable smoothing of high power periodicities operating directly in the Fourier spectrum through a polynomial fitting technique of the DFT. The main aim consists of disambiguating the characteristic slow varying periodicities, that can impair the MFDFA analysis, from the residual signal in order to study its correlation properties. The algorithm performances are evaluated on a simple benchmark test consisting of a persistent series where the Hurst exponent is known, with superimposed ten sinusoidal harmonics. Moreover, the behavior of the algorithm parameters is assessed computing the MFDFA on the well-known sunspot data, whose correlation characteristics are reported in literature. In both cases, the SSC-FD method eliminates the apparent crossover induced by the synthetic and natural periodicities. Results are compared with some existing detrending methods within the MFDFA paradigm. Finally, a study of the multifractal characteristics of the electric load time series detrendended by the SSC-FD algorithm is provided, showing a strong persistent behavior and an appreciable amplitude of the multifractal spectrum that allows to conclude that the series at hand has multifractal characteristics.

  9. Practical considerations in voltage stability assessment

    Energy Technology Data Exchange (ETDEWEB)

    Kundur, P.; Gao, B. [Powertech Labs. Inc., Surrey, BC (Canada)

    1994-12-31

    This paper deals with some of the most important practical issues related to voltage stability assessment of large practical systems. A brief discussion of the practical aspects of voltage stability problem and prevention of voltage instability is given first, followed by descriptions of different analytical techniques and tools for voltage stability analysis. Presentations of analytical tools is focused on the VSTAB program which incorporates the modal analysis, continuation power flow, and shortest distance to instability techniques, Finally, an example case study of a practical large system is presented. The case study illustrates how modal analysis is used to determine the most effective load shedding scheme for preventing voltage instability. (author) 15 refs., 2 figs., 2 tabs.

  10. Coordinated Voltage Control of Active Distribution Network

    Directory of Open Access Journals (Sweden)

    Xie Jiang

    2016-01-01

    Full Text Available This paper presents a centralized coordinated voltage control method for active distribution network to solve off-limit problem of voltage after incorporation of distributed generation (DG. The proposed method consists of two parts, it coordinated primal-dual interior point method-based voltage regulation schemes of DG reactive powers and capacitors with centralized on-load tap changer (OLTC controlling method which utilizes system’s maximum and minimum voltages, to improve the qualified rate of voltage and reduce the operation numbers of OLTC. The proposed coordination has considered the cost of capacitors. The method is tested using a radial edited IEEE-33 nodes distribution network which is modelled using MATLAB.

  11. Voltage Balancer for Electric Double Layer Capacitors

    Science.gov (United States)

    Mori, Kazuya; Takahashi, Shingo; Hasebe, Akio; Seki, Sumiko; Itoh, Takahiko

    Decrease in energy density of the storage system with several electric double layer capacitors (EDLCs) is caused by imbalance of voltage for each EDLC. In case of low power applications, conventional voltage balancer with constant voltage circuits is useful. However, it has some problems for high power applications such as electric vehicle. We have developed a new system to balance the voltage of EDLCs by removing a little energy. In any case, the system can store the energy in each EDLC equally. In the present research, a prototype of voltage balancer is produced for making use of a number of EDLCs and evaluated. The results confirm that the system is effective and suitable for high power applications.

  12. New series half-bridge converters with the balance input split capacitor voltages

    Science.gov (United States)

    Lin, Bor-Ren; Chiang, Huann-Keng; Wang, Shang-Lun

    2016-03-01

    This article presents a new dc/dc converter to perform the main functions of zero voltage switching (ZWS), low converter size, high switching frequency and low-voltage stress. Metal-oxide-semiconductor field-effect transistors (MOSFETs) with high switching frequency are used to reduce the converter size and increase circuit efficiency. To overcome low-voltage stress and high turn-on resistance of MOSFETs, the series half-bridge topology is adopted in the proposed converter. Hence, the low-voltage stress MOSFETs can be used for medium-input voltage applications. The asymmetric pulse-width modulation is used to generate the gating signals and achieve the ZWS. On the secondary side, the parallel connection of two diode rectifiers is adopted to reduce the current rating of passive components. On the primary side, the series connection of two transformers is used to balance two output inductor currents. Two flying capacitors are used to automatically balance the input split capacitor voltages. Finally, experiments with 1000 W rated power are performed to verify the theoretical analysis and the effectiveness of proposed converter.

  13. Characterization of voltage-gated Ca(2+ conductances in layer 5 neocortical pyramidal neurons from rats.

    Directory of Open Access Journals (Sweden)

    Mara Almog

    Full Text Available Neuronal voltage-gated Ca(2+ channels are involved in electrical signalling and in converting these signals into cytoplasmic calcium changes. One important function of voltage-gated Ca(2+ channels is generating regenerative dendritic Ca(2+ spikes. However, the Ca(2+ dependent mechanisms used to create these spikes are only partially understood. To start investigating this mechanism, we set out to kinetically and pharmacologically identify the sub-types of somatic voltage-gated Ca(2+ channels in pyramidal neurons from layer 5 of rat somatosensory cortex, using the nucleated configuration of the patch-clamp technique. The activation kinetics of the total Ba(2+ current revealed conductance activation only at medium and high voltages suggesting that T-type calcium channels were not present in the patches. Steady-state inactivation protocols in combination with pharmacology revealed the expression of R-type channels. Furthermore, pharmacological experiments identified 5 voltage-gated Ca(2+ channel sub-types - L-, N-, R- and P/Q-type. Finally, the activation of the Ca(2+ conductances was examined using physiologically derived voltage-clamp protocols including a calcium spike protocol and a mock back-propagating action potential (mBPAP protocol. These experiments enable us to suggest the possible contribution of the five Ca(2+ channel sub-types to Ca(2+ current flow during activation under physiological conditions.

  14. Reliability of supply of switchgear for auxiliary low voltage in substations extra high voltage to high voltage

    Directory of Open Access Journals (Sweden)

    Perić Dragoslav M.

    2015-01-01

    Full Text Available Switchgear for auxiliary low voltage in substations (SS of extra high voltages (EHV to high voltage (HV - SS EHV/HV kV/kV is of special interest for the functioning of these important SS, as it provides a supply for system of protection and other vital functions of SS. The article addresses several characteristic examples involving MV lines with varying degrees of independence of their supply, and the possible application of direct transformation EHV/LV through special voltage transformers. Auxiliary sources such as inverters and diesel generators, which have limited power and expensive energy, are also used for the supply of switchgear for auxiliary low voltage. Corresponding reliability indices are calculated for all examples including mean expected annual engagement of diesel generators. The applicability of certain solutions of switchgear for auxiliary low voltage SS EHV/HV, taking into account their reliability, feasibility and cost-effectiveness is analyzed too. In particular, the analysis of applications of direct transformation EHV/LV for supply of switchgear for auxiliary low voltage, for both new and existing SS EHV/HV.

  15. Calculation of harmonic losses and ampacity in low-voltage power cables when used for feeding large LED lighting loads

    Directory of Open Access Journals (Sweden)

    N. J. Milardovich

    2014-10-01

    Full Text Available A numerical investigation on the harmonic disturbances in low-voltage cables feeding large LED loads is reported. A frequency domain analysis on several commercially-available LEDs was performed to investigate the signature of the harmonic current injected into the power system. Four-core cables and four single-core cable arrangements (three phases and neutral of small, medium, and large conductor cross sections, with the neutral conductor cross section approximately equal to the half of the phase conductors, were examined. The cables were modelled by using electromagnetic finite-element analysis software. High harmonic power losses (up to 2.5 times the value corresponding to an undistorted current of the same rms value of the first harmonic of the LED current were found. A generalized ampacity model was employed for re-rating the cables. It was found that the cross section of the neutral conductor plays an important role in the derating of the cable ampacity due to the presence of a high-level of triplen harmonics in the distorted current. The ampacity of the cables should be derated by about 40 %, almost independent of the conductor cross sections. The calculation have shown that an incoming widespread use of LED lamps in lighting could create significant additional harmonic losses in the supplying low-voltage lines, and thus more severely harmonic emission limits should be defined for LED lamps.

  16. Principles for the establishment and rationalization of high voltage systems

    International Nuclear Information System (INIS)

    1995-06-01

    The Danish Ministry of the Environment appointed a working group to clarify some principles on which the choice between overhead and underground electric cables could be based. It is a growing wish in the country that overhead cables should be avoided in urban areas and also a strong desire to preserve the countryside from them. Thus protected areas must not be used for this purpose. A specific assessment must be made whenever a major line is to be established where electricity supply, reliability, economy, aesthetic and environmental interests, and possible alternative solutions are taken into consideration. The document presents the group's report on the reconstruction of old and the construction of new high voltage networks dealing with the aspects of protecting the natural landscape and the technical opportunities for laying the cables underground at various voltage levels in addition to cost estimates. Emphasis is on high voltage systems of 50 kW and above. Currently it is 6-20 times more expensive to use underground 400 kW alternating cable connections and 4-6 times more to use underground 150/132 AC connections. Costs vary in accordance with different voltage levels, dependent on local conditions. The undergrounding of existing 60/50 kW overhead lines is much more expensive than continuous maintenance. It is agreed that electricity utilities and regional authorities should cooperate on management and long-term planning and in structuring a detailed prioritization of the changes of the existing high-voltage network and future extension. Principles for the basis of this prioritization are given in detail. (AB)

  17. Analysis of operating conditions of the voltage transformer

    Directory of Open Access Journals (Sweden)

    Fastiy G. P.

    2017-12-01

    Full Text Available In electrical networks, constant monitoring of the electrical equipment operation is necessary. To accomplish this task, current transformers and voltage transformers (VT are used, on which the accuracy of electrical measurements, electricity metering, and the reliability of the emergency control system depend. The results of the analysis of the conditions for forming the magnetization of a voltage transformer in the mode with unilateral connection of overhead transmission lines, as well as variants of violations in the 110 kV network that may exist for a relatively long time have been presented. It should be noted that the considered network has its own peculiarities: the overhead transmission lines connected in series have a significant length and a low level of load, which may be a condition for the appearance of a transmission lines capacitive effect (the Ferranti effect, the latter can cause overvoltage. Overvoltage occurs when the operating modes are temporary in terms of operation, adverse combinations of network parameters take place, and can continue until the circuit and network modes change. Most often they appear in asymmetric modes, with short circuits to ground, etc. Asymmetric modes caused by incomplete-phase commutations and wire breaks on the overhead line, as well as wire breaks with subsequent disconnection of power transformers that can affect the voltage level on the VT have been considered. The possibility of VT magnetizing with a prolonged voltage rise in symmetric modes, namely, the manifestation of the Ferranti effect with various loads at substations up to complete switching-off and power transformers switching off has been investigated. The analysis of the measuring voltage transformer operating conditions has been based on materials provided by the "Kolenergo" services.

  18. Reliability Estimation of High Voltage Ceramic Capacitor by Failure Analysis

    International Nuclear Information System (INIS)

    Yang, Seok Jun; Kim, Jin Woo; Shin, Seung Woo; Lee, Hee Jin; Shin, Seung Hun; Ryu, Dong Su; Chang, Seog Weon

    2001-01-01

    This paper presents a result of failure analysis and reliability evaluation for high voltage ceramic capacitors. The failure modes and failure mechanisms were studied in two ways in order to estimate component life and failure rate. The causes of failure mechanisms for zero resistance phenomena under withstanding voltage test in high voltage ceramic capacitors molded by epoxy resin were studied by establishing an effective root cause failure analysis. Particular emphasis was placed on breakdown phenomena at the ceramic-epoxy interface. The validity of the results in this study was confirmed by the results of accelerated testing. Thermal cycling test for high voltage ceramic capacitor mounted on a magnetron were implemented. Delamination between ceramic and epoxy, which might cause electrical short in underlying circuitry, can occur during curing or thermal cycle. The results can be conveniently used to quickly identify defective lots, determine B 10 life estimation each lot at the level of inspection, and detect major changes in the vendors processes. Also, the condition for dielectric breakdown was investigated for the estimation of failure rate with load-strength interference model

  19. Congestion management considering voltage security of power systems

    International Nuclear Information System (INIS)

    Esmaili, Masoud; Shayanfar, Heidar Ali; Amjady, Nima

    2009-01-01

    Congestion in a power network is turned up due to system operating limits. To relieve congestion in a deregulated power market, the system operator pays to market participants, GENCOs and DISCOs, to alter their active powers considering their bids. After performing congestion management, the network may be operated with a low security level because of hitting some flows their upper limit and some voltages their lower limit. In this paper, a novel congestion management method based on the voltage stability margin sensitivities is introduced. Using the proposed method, the system operator so alleviates the congestion that the network can more retain its security. The proposed method not only makes the system more secure after congestion management than other methods already presented for this purpose but also its cost of providing security is lower than the earlier methods. Test results of the proposed method along with the earlier ones on the New-England test system elaborate the efficiency of the proposed method from the viewpoint of providing a better voltage stability margin and voltage profile as well as a lower security cost.

  20. Highly Reliable NPP Instrumentation Using Constant Voltage Feedback Circuits

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Seung J.; Choi, Bo H.; Kim, Ji H.; Rim, Chun T. [KAIST, Daejeon (Korea, Republic of)

    2014-08-15

    A highly reliable nuclear power plant (NPP) instrumentation using constant voltage feedback circuits is proposed. Contrary to conventional NPP instrumentation, two operational amplifiers are used at auxiliary building to supply constant DC voltage across the potentiometer or wheatstone bridge type sensors, such as resistance temperature detectors (RTD) and strain gauges. The proposed constant voltage feedback circuits maintain its output voltage as constant regardless of the length of lead wire from the auxiliary building to the sensors. A detail analysis of the proposed feedback circuits and design procedures including the internal resistance and parasitic LC components of lead wire are presented. A prototype with lumped RLC values for modeling lead wires is fabricated and experimentally verified to supply constant 10V up to 200m distance under 0.8% error. Due to its versatile characteristics with cost effective structure, the proposed scheme can be generally extended to pressure meters and water-level recorders to guarantee robust measurements without conventional current transducers under severe accidents.

  1. Propagation of disturbances as voltage fluctuations in transmission networks

    Directory of Open Access Journals (Sweden)

    Albert Hermina

    2016-08-01

    Full Text Available Significant changes occurred in the power system in Romania in recent years by reducing the power used in the system, the number of classic power sources in operation as well as by implementing renewable energy sources, have determined short circuit power reduction (node rigidity in the points where disturbing users are connected, that in the absence of adequate measures, result in disturbances above acceptable levels. The paper analyzes two power systems areas in which are connected users that cause voltage fluctuation. Disturbances as voltage fluctuations resulting in these nodes may exceed the acceptable values and can spread in the transmission network affecting power quality over large system areas. The analysis conducted reveals the influence of short circuit power in nodes where these users are connected and highlights the fact that in some cases (e.g. lines out of operation for maintenance, shutdown of classic units in the area the disturbances in the transmission network sent to the users at lower voltages may have values above those allowed. Technical Code of existing power transmission network makes no reference to voltage fluctuations, as a rule, in the electricity transmission network was considered that this phenomenon should not exist.

  2. Ultra-compact Marx-type high-voltage generator

    Science.gov (United States)

    Goerz, David A.; Wilson, Michael J.

    2000-01-01

    An ultra-compact Marx-type high-voltage generator includes individual high-performance components that are closely coupled and integrated into an extremely compact assembly. In one embodiment, a repetitively-switched, ultra-compact Marx generator includes low-profile, annular-shaped, high-voltage, ceramic capacitors with contoured edges and coplanar extended electrodes used for primary energy storage; low-profile, low-inductance, high-voltage, pressurized gas switches with compact gas envelopes suitably designed to be integrated with the annular capacitors; feed-forward, high-voltage, ceramic capacitors attached across successive switch-capacitor-switch stages to couple the necessary energy forward to sufficiently overvoltage the spark gap of the next in-line switch; optimally shaped electrodes and insulator surfaces to reduce electric field stresses in the weakest regions where dissimilar materials meet, and to spread the fields more evenly throughout the dielectric materials, allowing them to operate closer to their intrinsic breakdown levels; and uses manufacturing and assembly methods to integrate the capacitors and switches into stages that can be arranged into a low-profile Marx generator.

  3. The Rated Voltage Determination of DC Building Power Supply System Considering Human Beings Safety

    Science.gov (United States)

    Wang, Zhicheng; Yu, Kansheng; Xie, Guoqiang; Zou, Jin

    2018-01-01

    Generally two-level voltages are adopted for DC building power supply system. From the point of view of human beings safety, only the lower level voltage which may be contacted barehanded is discussed in this paper based on the related safety thresholds of human beings current effect. For several voltage levels below 100V recommended by IEC, the body current and current density of human electric shock under device normal work condition, as well as effect of unidirectional single impulse currents of short durations are calculated and analyzed respectively. Finally, DC 60V is recommended as the lower level rating voltage through the comprehensive consideration of technical condition and cost of safety criteria.

  4. Direct Evidence of Conformational Changes Associated with Voltage Gating in a Voltage Sensor Protein by Time-Resolved X-ray/Neutron Interferometry

    Science.gov (United States)

    2015-01-01

    The voltage sensor domain (VSD) of voltage-gated cation (e.g., Na+, K+) channels central to neurological signal transmission can function as a distinct module. When linked to an otherwise voltage-insensitive, ion-selective membrane pore, the VSD imparts voltage sensitivity to the channel. Proteins homologous with the VSD have recently been found to function themselves as voltage-gated proton channels or to impart voltage sensitivity to enzymes. Determining the conformational changes associated with voltage gating in the VSD itself in the absence of a pore domain thereby gains importance. We report the direct measurement of changes in the scattering-length density (SLD) profile of the VSD protein, vectorially oriented within a reconstituted phospholipid bilayer membrane, as a function of the transmembrane electric potential by time-resolved X-ray and neutron interferometry. The changes in the experimental SLD profiles for both polarizing and depolarizing potentials with respect to zero potential were found to extend over the entire length of the isolated VSD’s profile structure. The characteristics of the changes observed were in qualitative agreement with molecular dynamics simulations of a related membrane system, suggesting an initial interpretation of these changes in terms of the VSD’s atomic-level 3-D structure. PMID:24697545

  5. Fuel Cell/Electrochemical Cell Voltage Monitor

    Science.gov (United States)

    Vasquez, Arturo

    2012-01-01

    A concept has been developed for a new fuel cell individual-cell-voltage monitor that can be directly connected to a multi-cell fuel cell stack for direct substack power provisioning. It can also provide voltage isolation for applications in high-voltage fuel cell stacks. The technology consists of basic modules, each with an 8- to 16-cell input electrical measurement connection port. For each basic module, a power input connection would be provided for direct connection to a sub-stack of fuel cells in series within the larger stack. This power connection would allow for module power to be available in the range of 9-15 volts DC. The relatively low voltage differences that the module would encounter from the input electrical measurement connection port, coupled with the fact that the module's operating power is supplied by the same substack voltage input (and so will be at similar voltage), provides for elimination of high-commonmode voltage issues within each module. Within each module, there would be options for analog-to-digital conversion and data transfer schemes. Each module would also include a data-output/communication port. Each of these ports would be required to be either non-electrical (e.g., optically isolated) or electrically isolated. This is necessary to account for the fact that the plurality of modules attached to the stack will normally be at a range of voltages approaching the full range of the fuel cell stack operating voltages. A communications/ data bus could interface with the several basic modules. Options have been identified for command inputs from the spacecraft vehicle controller, and for output-status/data feeds to the vehicle.

  6. On-chip high-voltage generator design design methodology for charge pumps

    CERN Document Server

    Tanzawa, Toru

    2016-01-01

    This book provides various design techniques for switched-capacitor on-chip high-voltage generators, including charge pump circuits, regulators, level shifters, references, and oscillators.  Readers will see these techniques applied to system design in order to address the challenge of how the on-chip high-voltage generator is designed for Flash memories, LCD drivers, and other semiconductor devices to optimize the entire circuit area and power efficiency with a low voltage supply, while minimizing the cost.  This new edition includes a variety of useful updates, including coverage of power efficiency and comprehensive optimization methodologies for DC-DC voltage multipliers, modeling of extremely low voltage Dickson charge pumps, and modeling and optimum design of AC-DC switched-capacitor multipliers for energy harvesting and power transfer for RFID.

  7. Modeling generalized interline power-flow controller (GIPFC using 48-pulse voltage source converters

    Directory of Open Access Journals (Sweden)

    Amir Ghorbani

    2018-05-01

    Full Text Available Generalized interline power-flow controller (GIPFC is one of the voltage-source controller (VSC-based flexible AC transmission system (FACTS controllers that can independently regulate the power-flow over each transmission line of a multiline system. This paper presents the modeling and performance analysis of GIPFC based on 48-pulsed voltage-source converters. This paper deals with a cascaded multilevel converter model, which is a 48-pulse (three levels voltage source converter. The voltage source converter described in this paper is a harmonic neutralized, 48-pulse GTO converter. The GIPFC controller is based on d-q orthogonal coordinates. The algorithm is verified using simulations in MATLAB/Simulink environment. Comparisons between unified power flow controller (UPFC and GIPFC are also included. Keywords: Generalized interline power-flow controller (GIPFC, Voltage source converter (VCS, 48-pulse GTO converter

  8. A non-linear voltage dependent charge movement in frog skeletal muscle.

    Science.gov (United States)

    Chandler, W K; Rakowski, R F; Schneider, M F

    1976-01-01

    1. Voltage-clamp experiments were carried out using the three microelectrode technique. Using this method membrane current density at V1 is proportional to deltaV( = V2 - V1) where V1 and V2 are voltages at distances 1 and 21 from the end of a fibre. Voltage dependent sodium currents were blocked by tetrodotoxin, potassium by tetraethylammonium ions and rubidium. Contraction was blocked by adding sucrose, 467 mM. 2. The current deltaV (control) associated with a positive voltage step from a hyperpolarized conditioning voltage to the holding potential, -80 mV, showed two components, a capacitative transient which decayed rapidly and a maintained steady level...

  9. Voltage controlled spintronics device for logic applications.

    Energy Technology Data Exchange (ETDEWEB)

    Bader, S. D.; You, C.-Y.

    1999-09-03

    We consider logic device concepts based on our previously proposed spintronics device element whose magnetization orientation is controlled by application of a bias voltage instead of a magnetic field. The basic building block is the voltage-controlled rotation (VCR) element that consists of a four-layer structure--two ferromagnetic layers separated by both nanometer-thick insulator and metallic spacer layers. The interlayer exchange coupling between the two ferromagnetic layers oscillates as a function of applied voltage. We illustrate transistor-like concepts and re-programmable logic gates based on VCR elements.

  10. High voltage electricity installations a planning perspective

    CERN Document Server

    Jay, Stephen Andrew

    2006-01-01

    The presence of high voltage power lines has provoked widespread concern for many years. High Voltage Electricity Installations presents an in-depth study of policy surrounding the planning of high voltage installations, discussing the manner in which they are percieved by the public, and the associated environmental issues. An analysis of these concerns, along with the geographical, environmental and political influences that shape their expression, is presented. Investigates local planning policy in an area of the energy sector that is of highly topical environmental and public concern Cover

  11. Analysis of NSTX TF Joint Voltage Measurements

    International Nuclear Information System (INIS)

    Woolley R

    2005-01-01

    This report presents findings of analyses of recorded current and voltage data associated with 72 electrical joints operating at high current and high mechanical stress. The analysis goal was to characterize the mechanical behavior of each joint and thus evaluate its mechanical supports. The joints are part of the toroidal field (TF) magnet system of the National Spherical Torus Experiment (NSTX) pulsed plasma device operating at the Princeton Plasma Physics Laboratory (PPPL). Since there is not sufficient space near the joints for much traditional mechanical instrumentation, small voltage probes were installed on each joint and their voltage monitoring waveforms have been recorded on sampling digitizers during each NSTX ''shot''

  12. Reduced semiconductor three-level interline dynamic voltage restorer

    DEFF Research Database (Denmark)

    Zhang, Lei; Loh, Poh Chang; Gao, Feng

    2011-01-01

    IDVR system are mainly attributed to its complexity in topology and underutilizations of semiconductors. Aimed to improve the system in these aspects, the paper proposes a new IDVR topology with 25% reduction in semiconductors totally used. The theoretical analysis and its operating principles are also...

  13. A strategy for protection of high voltage systems using resistive superconducting fault current limiters

    Science.gov (United States)

    Schettino, H. J.; Andrade, R. de, Jr.; Polasek, A.; Kottonau, D.; de Sousa, W. T. B.

    2018-01-01

    This work describes an use of a resistive superconducting fault current limiter (R-SFCL) device based on second generation high temperature superconductors tapes (2G tapes), using a thermal-electrical analogy method to represent heat exchanges. The considered SFCL is supposed to be inserted into the coupling point of a new generation unit to a 12 bar CIGRE benchmark transmission system. The strategy is the investigation of the limitation performance in the high voltage grid by connecting the SFCL at medium voltage grid. We evaluated the performance of the SFCL through the analysis of two cases of faults in different points of the system. Results show that a correct design of the SFCL may effectively limit the contribution of fault currents in the high voltage side. Additionally, it was possible to investigate the behavior of the device internal variables such as the temperature of the superconducting layers for the different cases studied.

  14. Effect of Variation in Voltage on the Synthesis of Ag Nanopowder by Pulsed Wire Evaporation

    Directory of Open Access Journals (Sweden)

    Joon-Woo Song

    2012-01-01

    Full Text Available Nanosized Ag particles were obtained in liquid medium, which is composed of deionized water and sodium hexametaphosphate, using pulsed wire evaporation within hundreds of microseconds from pure initial Ag wire (99.98%, with varying voltage. Changes in powder morphology and microstructure due to change in supply voltage was observed by FE-SEM and HR-TEM, and phase structure of powders was analyzed by XRD. The results revealed that average particle size slightly increased with increasing supply voltage without any impurity and oxide phase, which was explained in terms of addition of stabilizer into the coolant liquid. The experimental results also suggest that addition of sodium hexametaphosphate into the coolant liquid is good for enhancing the dispersibility property of silver nanopowders.

  15. Architecture, Voltage, and Components for a Turboelectric Distributed Propulsion Electric Grid

    Science.gov (United States)

    Armstrong, Michael J.; Blackwelder, Mark; Bollman, Andrew; Ross, Christine; Campbell, Angela; Jones, Catherine; Norman, Patrick

    2015-01-01

    The development of a wholly superconducting turboelectric distributed propulsion system presents unique opportunities for the aerospace industry. However, this transition from normally conducting systems to superconducting systems significantly increases the equipment complexity necessary to manage the electrical power systems. Due to the low technology readiness level (TRL) nature of all components and systems, current Turboelectric Distributed Propulsion (TeDP) technology developments are driven by an ambiguous set of system-level electrical integration standards for an airborne microgrid system (Figure 1). While multiple decades' worth of advancements are still required for concept realization, current system-level studies are necessary to focus the technology development, target specific technological shortcomings, and enable accurate prediction of concept feasibility and viability. An understanding of the performance sensitivity to operating voltages and an early definition of advantageous voltage regulation standards for unconventional airborne microgrids will allow for more accurate targeting of technology development. Propulsive power-rated microgrid systems necessitate the introduction of new aircraft distribution system voltage standards. All protection, distribution, control, power conversion, generation, and cryocooling equipment are affected by voltage regulation standards. Information on the desired operating voltage and voltage regulation is required to determine nominal and maximum currents for sizing distribution and fault isolation equipment, developing machine topologies and machine controls, and the physical attributes of all component shielding and insulation. Voltage impacts many components and system performance.

  16. The dependence of molecular transmembrane electrotransfer efficiency on medium conductivity and osmotic pressure

    OpenAIRE

    Jakutavičiūtė, Milda; Ruzgys, Paulius; Šatkauskas, Saulius

    2014-01-01

    The electrotransfer efficiency was evaluated for different external medium conductivities, osmotic pressures and electric pulse voltages. It was found that increase in conductivity or decrease in electric pulse strength decreases electrotransfer efficiency. Decrease in osmotic pressure tends to decrease electrotransfer efficiency.

  17. Origin of the transition voltage in gold–vacuum–gold atomic junctions

    KAUST Repository

    Wu, Kunlin

    2012-12-13

    The origin and the distance dependence of the transition voltage of gold-vacuum-gold junctions are investigated by employing first-principles quantum transport simulations. Our calculations show that atomic protrusions always exist on the electrode surface of gold-vacuum-gold junctions fabricated using the mechanically controllable break junction (MCBJ) method. The transition voltage of these gold-vacuum-gold junctions with atomically sharp electrodes is determined by the local density of states (LDOS) of the apex gold atom on the electrode surface rather than by the vacuum barrier shape. More specifically, the absolute value of the transition voltage roughly equals the rising edge of the LDOS peak contributed by the 6p atomic orbitals of the gold atoms protruding from the electrode surface, whose local Fermi level is shifted downwards when a bias voltage is applied. Since the LDOS of the apex gold atom depends strongly on the exact shape of the electrode, the transition voltage is sensitive to the variation of the atomic configuration of the junction. For asymmetric junctions, the transition voltage may also change significantly depending on the bias polarity. Considering that the occurrence of the transition voltage requires the electrode distance to be larger than a critical value, the interaction between the two electrodes is actually rather weak. Consequently, the LDOS of the apex gold atom is mainly determined by its local atomic configuration and the transition voltage only depends weakly on the electrode distance as observed in the MCBJ experiments. © 2013 IOP Publishing Ltd.

  18. Origin of the transition voltage in gold–vacuum–gold atomic junctions

    International Nuclear Information System (INIS)

    Wu Kunlin; Bai Meilin; Hou Shimin; Sanvito, Stefano

    2013-01-01

    The origin and the distance dependence of the transition voltage of gold–vacuum–gold junctions are investigated by employing first-principles quantum transport simulations. Our calculations show that atomic protrusions always exist on the electrode surface of gold–vacuum–gold junctions fabricated using the mechanically controllable break junction (MCBJ) method. The transition voltage of these gold–vacuum–gold junctions with atomically sharp electrodes is determined by the local density of states (LDOS) of the apex gold atom on the electrode surface rather than by the vacuum barrier shape. More specifically, the absolute value of the transition voltage roughly equals the rising edge of the LDOS peak contributed by the 6p atomic orbitals of the gold atoms protruding from the electrode surface, whose local Fermi level is shifted downwards when a bias voltage is applied. Since the LDOS of the apex gold atom depends strongly on the exact shape of the electrode, the transition voltage is sensitive to the variation of the atomic configuration of the junction. For asymmetric junctions, the transition voltage may also change significantly depending on the bias polarity. Considering that the occurrence of the transition voltage requires the electrode distance to be larger than a critical value, the interaction between the two electrodes is actually rather weak. Consequently, the LDOS of the apex gold atom is mainly determined by its local atomic configuration and the transition voltage only depends weakly on the electrode distance as observed in the MCBJ experiments. (paper)

  19. Distance protection of multiple-circuit shared tower transmission lines with different voltages

    DEFF Research Database (Denmark)

    Silva, Filipe Miguel Faria da; Bak, Claus Leth

    2017-01-01

    Multiple-circuit transmission lines combining different voltage levels in one tower present extra challenges when setting a protection philosophy, as faults between voltage levels are possible. In this study, the fault loop impedance of combined faults is compared with the fault loop impedance......-phase-to-ground faults. It is also demonstrated that the fault loop impedance of combined faults is more resistive, when compared with equivalent single-phase-to-ground faults. It is concluded that the settings used to protect a line against single-phase-to-ground faults are capable of protecting the line against...... combined faults, being advised to increase the resistive limit of the protection zone, if the network has lower short-circuit power. It is recommended to assure that the fault can only happen for cases where the faulted phase from the higher voltage level leads the faulted phase from the lower voltage...

  20. Nested high voltage generator/particle accelerator

    International Nuclear Information System (INIS)

    Adler, R.J.

    1992-01-01

    This patent describes a modular high voltage particle accelerator having an emission axis and an emission end, the accelerator. It comprises: a plurality of high voltage generators in nested adjacency to form a nested stack, each the generator comprising a cup-like housing having a base and a tubular sleeve extending from the base, a primary transformer winding encircling the nested stack; a secondary transformer winding between each adjacent pair of housings, magnetically linked to the primary transformer winding through the gaps; a power supply respective to each of the secondary windings converting alternating voltage from its respective secondary winding to d.c. voltage, the housings at the emission end forming a hollow throat for particle acceleration, a vacuum seal at the emission end of the throat which enables the throat to be evacuated; a particle source in the thrond power means to energize the primary transformer winding