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33 results on '"Van Den Brom, H."'

1. Performance evaluation of instrument transformers in power quality measurements: activities and results from 19NRM05 IT4PQ project

Author

Crotti, G., primary, Letizia, P. S., additional, Meyer, J., additional, Stiegler, R., additional, Agazar, M., additional, Istrate, D., additional, Chen, Y., additional, Mohns, E., additional, Cayci, H., additional, Ayhan, B., additional, van den Brom, H., additional, Muñoz, F., additional, Mazza, P., additional, Palladini, D., additional, Luiso, M., additional, Landi, C., additional, Tinarelli, R., additional, and Mingotti, A., additional

Published
2023
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4. Shot Noise Suppression in Metallic Quantum Point Contacts

Author

van den Brom, H. E., van Ruitenbeek, J. M., Beig, R., editor, Ehlers, J., editor, Frisch, U., editor, Hepp, K., editor, Hillebrandt, W., editor, Imboden, D., editor, Jaffe, R. L., editor, Kippenhahn, R., editor, Lipowsky, R., editor, Löhneysen, H., editor, Ojima, I., editor, Weidenmüller, H. A., editor, Wess, J., editor, Zittartz, J., editor, Reguera, David, editor, Rubí, José Miguel, editor, Platero, Gloria, editor, and Bonilla, Luis López, editor

Published
2000
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12. On the limitations of harmonic modeling with measured inputs - A case study

Author

Babaev, S., Cuk, V., Cobben, J.F.G., van den Brom, H., Rietveld, G., Jongepier, A., Babaev, S., Cuk, V., Cobben, J.F.G., van den Brom, H., Rietveld, G., and Jongepier, A.

Abstract

This paper proposes a method for determining the limitations of harmonic modeling based on measured emissions and standard harmonic impedance models using synchronized spectrum measurements. It was found that the calculation method performs very well for the fundamental frequency and reasonably well for some harmonic orders. The limiting factors based on measurement uncertainty are discussed, and some proposals for future studies are given.

Published
2018

13. Results of an International Comparison of Instrument Current Transformers up to 10 kA at 50 Hz Frequency

Author

Draxler, K., primary, Styblikova, R., additional, Hlavacek, J., additional, Rietveld, G., additional, van den Brom, H. E., additional, Schnaitt, M., additional, Waldmann, W., additional, Dimitrov, E., additional, Cincar-Vujovic, T., additional, Paczek, B., additional, Sadkowski, G., additional, Crotti, G., additional, Martin, R., additional, Garnacho, F., additional, Blanc, I., additional, Kampfer, R., additional, Mester, C., additional, Wheaton, A., additional, Mohns, E., additional, Bergman, A., additional, Hammarquist, M., additional, Cayci, H., additional, Hallstrom, J., additional, and Suomalainen, E-P., additional

Published
2018
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15. International Comparison Of Current Transformer Calibration Systems Up To 10 Ka At 50 Hz Frequency

Author

Draxler, K., Styblikova, R., Rietveld, G., van den Brom, H., Schnaitt, M., Waldmann, W., Dimitrov, E., Cincar-Vujovic, T., Paczek, B., Sadkowski, G., Crotti, G., Martin, R., Garnacho, F., Blanc, I., Kampfer, R., Mester, C., Wheaton, A., Mohns, E., Bergman, A., and Hammarquist, M.

Abstract

Current transformers (CTs) are precision devices that scale high currents down to values that can be easily handled by measurement equipment. To support CT applications in revenue metering, a comparison on AC current transformer calibration systems was performed among 15 European national metrology institutes using a precision CT as the travelling device. The first comparison results for the transformation ratios (4, 5, 6, 8, 10) kA/5 A of the travelling CT at nominal burden of 5 VA and 15 VA indicate good agreement between the participating laboratories. The main differences are found for phase displacement, at least partly caused by the instability of the traveling standard.

Published
2016

17. International comparison of current transformer calibration systems up to 10 kA at 50 Hz frequency

Author

Draxler, K., primary, Styblikova, R., additional, Rietveld, G., additional, van den Brom, H., additional, Schnaitt, M., additional, Waldmann, W., additional, Dimitrov, E., additional, Cincar-Vujovic, T., additional, Paczek, B., additional, Sadkowski, G., additional, Crotti, G., additional, Martin, R., additional, Garnacho, F., additional, Blanc, I., additional, Kampfer, R., additional, Mester, C., additional, Wheaton, A., additional, Mohns, E., additional, Bergman, A., additional, Hammarquist, M., additional, Cayci, H., additional, Hallstrom, J., additional, and Suomalainen, E-P., additional

Published
2016
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20. Binary Josephson Array Power Standard

Author

Behr, R., primary, Palafox, L., additional, Williams, J. M., additional, Djordjevic, S., additional, Eklund, G., additional, Van Den Brom, H. E., additional, Jeanneret, B., additional, Nissil, J., additional, Katkov, A., additional, and Benz, S. P., additional

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23. Realisation of a Quantum Standard for AC Voltage: Overview of a European Research Project

Author

Chevtchenko, O. A., primary, Van Den Brom, H. E., additional, Houtzager, E., additional, Behr, R., additional, Kohlmann, J., additional, Williams, J. M., additional, B. M. Janssen, T. J., additional, Palafox, L., additional, Djordjevic, S., additional, Monnoye, O., additional, Poletaeff, A., additional, Piquemal, F., additional, Lapuh, R., additional, Rydler, K.-e., additional, and Eklund, G., additional

Published
2004
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25. Analysis of different measurement set-ups for a programmable Josephson voltage standard

Author

Behr, R., primary, Kohlmann, J., additional, Janssen, J.T., additional, Kleinschmidt, P., additional, Williams, J.M., additional, Lo-Hive, J.-P., additional, Piquemal, F., additional, Hetland, P.O., additional, Reymann, D., additional, Eklund, G., additional, Hof, C., additional, Jeanneret, B., additional, Chevtchenko, O., additional, Houtzager, E., additional, Van Den Brom, H., additional, Sosso, A., additional, Andreone, D., additional, Penttila, J., additional, and Helisto, P., additional

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27. How Instrument Transformers Influence Power Quality Measurements: A Proposal of Accuracy Verification Tests

Author

Gabriella Crotti, Yeying Chen, Huseyin Çayci, Giovanni D’Avanzo, Carmine Landi, Palma Sara Letizia, Mario Luiso, Enrico Mohns, Fabio Muñoz, Renata Styblikova, Helko van den Brom, Crotti, G., Chen, Y., Cayci, H., D'Avanzo, G., Landi, C., Letizia, P. S., Luiso, M., Mohns, E., Munoz, F., Styblikova, R., and van den Brom, H.

Subjects
power system measurements, instrument transformers, power quality, accuracy, Electrical and Electronic Engineering, Biochemistry, Instrumentation, Atomic and Molecular Physics, and Optics, instrument transformer, Analytical Chemistry
Abstract

The integration of renewable energy sources on a large scale in the electrical energy distribution systems, as well as the widespread of non-linear loads, has led to a significant increase in power quality (PQ) disturbances. For this reason, PQ monitoring is also becoming a key task in medium voltage (MV) grids. The measurement of PQ at MV levels can only be performed using instrument transformers (ITs) to scale down the level of voltage and current to levels suitable for the input stage of PQ instruments. However, no international standards currently require the verification of the errors introduced by ITs in the measurement of PQ phenomena. Moreover, this issue is only partially addressed in the scientific literature, where papers dealing with specific and limited aspects of the problem can be found. For this reason, this paper aims to comprehensively assess the issue, proposing IT accuracy verification tests for different PQ parameters. First, a set of PQ phenomena relevant for IT testing is chosen, as well as the associated ranges of variation, based on a review of the enforced standards and the scientific literature. For each selected PQ phenomenon, possible performance indices and test waveforms are proposed. Finally, the proposed procedure is validated by applying it to the characterization of two different types of commercial voltage transformers.

Published
2022

28. Accurate Measurement of Energy Dissipated in Braking Rheostats in DC Railway Systems

Author

Helko E. van den Brom, Yljon Seferi, Andreas Wank, Domenico Giordano, Danielle Gallo, CPEM Digest (Conference on Precision Electromagnetic Measurements), Van Den Brom, H., Giordano, D., Gallo, D., Wank, A., and Seferi, Y.

Subjects
HE, Computer science, TK, System of measurement, 020208 electrical & electronic engineering, 02 engineering and technology, Current measurement, Automotive engineering, law.invention, Metrology, Reliability (semiconductor), Smart grid, Transducer, law, measurement uncertainty, energy measurement, 0202 electrical engineering, electronic engineering, information engineering, transducers, Measurement uncertainty, Resistor, rail transportation, Energy (signal processing)
Abstract

This paper describes the measurement system used to monitor the energy dissipated in the braking rheostat resistors on board a locomotive operating in a DC rail system. The aim of the activity is the accurate estimation of the energy, nowadays wasted, that could be recovered thanks to the implementation of the smart grid paradigm in the DC railway system. To provide metrological reliability to the measured wasted energy, a preliminary identification and estimation of the uncertainty is provided. The target uncertainty of the measurements is 1 %.

Published
2020

29. Methodology for the Accurate Measurement of the Power Dissipated by Braking Rheostats

Author

D. Signorino, Martin Šíra, Domenico Giordano, Helko E. van den Brom, Daniele Gallo, Giordano, D., Signorino, D., Gallo, D., van den Brom, H. E., and Sira, M.

Subjects
Computer science, 020209 energy, power measurement, ComputerApplications_COMPUTERSINOTHERSYSTEMS, 02 engineering and technology, lcsh:Chemical technology, Biochemistry, Article, Automotive engineering, current transducer, DC locomotive, Analytical Chemistry, law.invention, Chopper, braking rheostat, law, 0202 electrical engineering, electronic engineering, information engineering, lcsh:TP1-1185, Electrical and Electronic Engineering, Ampere, Instrumentation, regenerative braking, frequency characterization, chopped current, railway system, 020208 electrical & electronic engineering, Atomic and Molecular Physics, and Optics, Power (physics), Regenerative brake, Resistor, Energy (signal processing)
Abstract

The energy efficiency of transportation is a crucial point for the rail and metro system today. The optimized recovery of the energy provided by the electrical braking can lead to savings of about 10% to 30%. Such figures can be reached by infrastructure measures which allow the recovery of the breaking energy that is not directly consumed by the rail system and dissipated in rheostat resistors. A methodology for the accurate estimate of such energy is valuable for a reliable evaluation of the cost&ndash, benefit ratio associated with the infrastructural investment. The energy can be estimated by measuring a braking current flowing in the rheostats. The varying duty-cycle associated with the high dynamic variation, from zero to thousands of amperes, makes the current measurement very challenging. Moreover, the digitization of such waveforms introduces systematic errors that affect the energy estimation. To overcome these issues, this paper proposes a technique to measure the power and energy dissipated by the rheostat of a DC operated train with high accuracy. By means of an accurate model of the electrical braking circuit (chopper and rheostat) and the frequency characterization of the current transducer, a correction coefficient as a function of the duty-cycle is estimated. The method is then applied to data recorded during a measurement campaign performed on-board a 1.5 kV train of Metro de Madrid during normal operation. Using the proposed technique, the estimation of the dissipated braking energy is improved by 20%.

Published
2020

30. Accurate Measurements of Energy, Efficiency and Power Quality in the Electric Railway System

Author

H.E. van den Brom, Domenico Giordano, F. Gamacho, Martin Šíra, C. Spalvieri, C. Mester, N. Navarro, L. Donadio, Andrea Mariscotti, A. De Santiago Laporte, Daniele Gallo, Paul Clarkson, D. Istrate, M. Porzio, Andrew J. Roscoe, Antonio Fernández-Cardador, Conference on Precision Electromagnetic Measurements, Giordano, D., Clarkson, P., Gamacho, F., Van Den Brom, H. E., Donadio, L., Fernandez-Cardador, A., Spalvieri, C., Gallo, D., Istrate, D., De Santiago Laporte, A., Mariscotti, A., Mester, C., Navarro, N., Porzio, M., Roscoe, A., and Sira, M.

Subjects
Engineering, measurement standards, Atomic and Molecular Physics, and Optic, measurement standard, Energy management, 020209 energy, RSS, Electric power and energy measurement, power quality, power system simulation, railway systems, signal processing, 02 engineering and technology, 0202 electrical engineering, electronic engineering, information engineering, Calibration, Electrical and Electronic Engineering, Instrumentation, Estimation, Radiation, business.industry, 020208 electrical & electronic engineering, computer.file_format, railway system, Metrology, Systems engineering, Power quality, business, computer, Energy (signal processing), Efficient energy use
Abstract

This paper describes a new EU co-funded project on metrology for smart energy management is electric railway systems (MyRailS). The project involves 7 national metrology institutes, 3 universities and 6 railway companies. Research focusses on the following topics: i) new calibration facilities for energy meters on-board installed, ii) power quality monitoring systems, iii) accurate estimation of the saved energy by the installation of new reversible substations (RSS) and iv) by the adoption of eco-driving strategies.

Published
2018

31. Power Grids and Instrument Transformers up to 150 kHz: A Review of Literature and Standards.

Author

Agazar M, D'Avanzo G, Frigo G, Giordano D, Iodice C, Letizia PS, Luiso M, Mariscotti A, Mingotti A, Munoz F, Palladini D, Rietveld G, and van den Brom H

Abstract

The phenomenon of high-frequency distortion (HFD) in the electric grids, at both low-voltage (LV) and medium-voltage (MV) levels, is gaining increasing interest within the scientific and technical community due to its growing occurrence and the associated impact. These disturbances are mainly injected into the grid by new installed devices, essential for achieving decentralized generation based on renewable sources. In fact, these generation systems are connected to the grid through power converters, whose switching frequencies are significantly increasing, leading to a corresponding rise in the frequency of the injected disturbances. HFD represents a quite recent issue, but numerous scientific papers have been published in recent years on this topic. Furthermore, various international standards have also covered it, to provide guidance on instrumentation and related algorithms and indices for the measurement of these phenomena. When measuring HFD in MV grids, it is necessary to use instrument transformers (ITs) to scale voltages and currents to levels fitting with the input stages of power quality (PQ) instruments. In this respect, the recently released Edition 2 of the IEC 61869-1 standard extends the concept of the IT accuracy class up to 500 kHz; however, the IEC 61869 standard family provides guidelines on how to test ITs only at power frequency. This paper provides an extensive review of literature, standards, and the main outputs of European research projects focusing on HFD and ITs. This preliminary study of the state-of-the-art represents an essential starting point for defining significant waveforms to test ITs and, more generally, to achieve a comprehensive understanding of HFD. In this framework, this paper provides a summary of the most common ranges of amplitude and frequency variations of actual HFD found in real grids, the currently adopted measurement methods, and the normative open challenges to be addressed.

Published
2024
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32. How Instrument Transformers Influence Power Quality Measurements: A Proposal of Accuracy Verification Tests.

Author

Crotti G, Chen Y, Çayci H, D'Avanzo G, Landi C, Letizia PS, Luiso M, Mohns E, Muñoz F, Styblikova R, and van den Brom H

Abstract

The integration of renewable energy sources on a large scale in the electrical energy distribution systems, as well as the widespread of non-linear loads, has led to a significant increase in power quality (PQ) disturbances. For this reason, PQ monitoring is also becoming a key task in medium voltage (MV) grids. The measurement of PQ at MV levels can only be performed using instrument transformers (ITs) to scale down the level of voltage and current to levels suitable for the input stage of PQ instruments. However, no international standards currently require the verification of the errors introduced by ITs in the measurement of PQ phenomena. Moreover, this issue is only partially addressed in the scientific literature, where papers dealing with specific and limited aspects of the problem can be found. For this reason, this paper aims to comprehensively assess the issue, proposing IT accuracy verification tests for different PQ parameters. First, a set of PQ phenomena relevant for IT testing is chosen, as well as the associated ranges of variation, based on a review of the enforced standards and the scientific literature. For each selected PQ phenomenon, possible performance indices and test waveforms are proposed. Finally, the proposed procedure is validated by applying it to the characterization of two different types of commercial voltage transformers.

Published
2022
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33. Axial length as a risk factor to branch retinal vein occlusion.

Author

Timmerman EA, de Lavalette VW, and van den Brom HJ

Subjects
Aged, Aged, 80 and over, Anthropometry, Female, Humans, Male, Middle Aged, Refractive Errors complications, Refractive Errors pathology, Risk Factors, Anterior Eye Segment anatomy & histology, Eye anatomy & histology, Retinal Vein Occlusion etiology
Abstract

Purpose: To determine whether axial length is a factor in branch retinal vein occlusion., Methods: Axial length measurements in a group of 24 patients with a unilateral branch retinal vein occlusion were compared with the axial length measurements in a control group. Axial length measurements were taken with an A-scan; affected and unaffected eyes were measured. The control group consisted of 24 individuals who matched the patients in the branch retinal vein occlusion group in age, systemic hypertension status, and diabetes mellitus status., Results: The affected and fellow eye in patients in the branch retinal vein occlusion group did not differ statistically in axial length (P = 0.26). The mean axial length of affected eyes in the branch retinal vein occlusion group was 22.76 +/- 0.92 mm, and the mean axial length of control eyes was 23.36 +/- 1.08 mm. The difference in axial length between the eyes with a branch retinal vein occlusion and the eyes in the control group was statistically significant (P = 0.023)., Conclusion: The axial length of affected eyes of patients with branch retinal vein occlusion was on average 0.60 mm shorter than that of eyes of matched controls (95% confidence interval, 0.30-0.90 mm). The shorter axial length could be a local risk factor in the pathogenesis of a branch retinal vein occlusion.

Published
1997
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