Change search
Link to record
Permanent link

Direct link
BETA
Alternative names
Publications (10 of 18) Show all publications
Meisner, J., Elg, A. P., Hallstrom, J., Passon, S., Havunen, J., Bergman, A. & Nordlund, M. (2018). Intercomparison of reference measuring systems for lightning impulses between three National Metrology Institutes. In: ICHVE 2018 - 2018 IEEE International Conference on High Voltage Engineering and Application: . Paper presented at 2018 IEEE International Conference on High Voltage Engineering and Application, ICHVE 2018, 10 September 2018 through 13 September 2018.
Open this publication in new window or tab >>Intercomparison of reference measuring systems for lightning impulses between three National Metrology Institutes
Show others...
2018 (English)In: ICHVE 2018 - 2018 IEEE International Conference on High Voltage Engineering and Application, 2018Conference paper, Published paper (Refereed)
Abstract [en]

In one of the largest and most extensive measurement campaigns to date, the measuring systems for lightning impulses (LI) of the National Metrology Institutes (NMIs) of Germany (PTB), Sweden (RISE) and Finland (VTT MIKES) have been compared. In the high-voltage laboratory of PTB, lightning impulse comparisons were carried out at voltages up to 1500 kV. The test voltage, front time, time to half-value and the relative overshoot magnitude of seven systems have been compared. The results confirm the capabilities and uncertainties of the participating metrology institutes and even enable an improvement of those. Finally, the question, whether an uncertainty of less than 0.5 % for peak values and 1 % for time parameters for NMI reference measuring systems for a lightning impulse up to at least 800 kV is achievable, will be addressed.

Keywords
Engineering, Industrial engineering, High voltage laboratories, Intercomparisons, Lightning impulse, Measurement campaign, Measuring systems, National metrology institutes, Test voltage, Time parameter, Lightning
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-38223 (URN)10.1109/ICHVE.2018.8642002 (DOI)2-s2.0-85063102203 (Scopus ID)9781538650868 (ISBN)
Conference
2018 IEEE International Conference on High Voltage Engineering and Application, ICHVE 2018, 10 September 2018 through 13 September 2018
Available from: 2019-04-02 Created: 2019-04-02 Last updated: 2019-06-20Bibliographically approved
Elg, A. P. (2018). Qualifying a Transient Recorder for Traceable Measurements of Very Fast Transients. In: CPEM 2018 - Conference on Precision Electromagnetic Measurements: . Paper presented at 2018 Conference on Precision Electromagnetic Measurements, CPEM 2018, 8 July 2018 through 13 July 2018.
Open this publication in new window or tab >>Qualifying a Transient Recorder for Traceable Measurements of Very Fast Transients
2018 (English)In: CPEM 2018 - Conference on Precision Electromagnetic Measurements, 2018Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents the qualification of a transient recorder used in a system for traceable measurements of Very Fast Transients. The system is designed for traceable measurements of VFT up to 100 kV, having a target settling time < 10 ns, a peak voltage error < 1\%, and a front time error < 5\%. The rise time of the digitizer is 1.6 ns at 50Ω and 1.2 ns at 1 MΩ. Step responses show settling times of 4.5 ns. A convolution method gives a peak voltage error of 0.12% and a front time error of 4.1% for 4.5ns front times. © 2018 IEEE.

Keywords
Fast transients, high voltage, measurement uncertainty, traceability, Convolution, Errors, Convolution methods, Measurements of, Settling time, Very fast transients, Uncertainty analysis
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-36600 (URN)10.1109/CPEM.2018.8500980 (DOI)2-s2.0-85057006228 (Scopus ID)9781538609736 (ISBN)
Conference
2018 Conference on Precision Electromagnetic Measurements, CPEM 2018, 8 July 2018 through 13 July 2018
Available from: 2018-12-17 Created: 2018-12-17 Last updated: 2019-06-20Bibliographically approved
Bergman, A., Nordlund, M., Elg, A. P., Meisner, J., Passon, S., Hällström, J. & Lehtonen, T. (2017). Characterization of a fast step generator. In: : . Paper presented at International Symposium on High-Voltage Engineering, 2017.
Open this publication in new window or tab >>Characterization of a fast step generator
Show others...
2017 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Lighting impulse measurements are made as a matter of routine in high voltage testing of high-voltage electrical equipment. The test is often decisive for acceptance of the equipment under test, and consequently proper and precise calibration of the measuring system is needed. The present work centres on the need to quantify the errors of reference measuring systems for lightning impulse. Scale factor determination at low frequency (or DC) is the starting point for this determination. The extrapolation from this frequency domain to the domain where microsecond pulses must be faithfully captured requires application either of methods in the frequency domain or in the time domain. Radio frequency measurements are only well defined for coaxial structures and at impedances in the range of 50 O or thereabouts, making them difficult to apply to the large structures of high-voltage measuring systems. The converse method in the time domain is to apply a Dirac impulse to the system and calculate the response to an assumed input signal by convolution. A true Dirac pulse is not readily available and in practice the applied pulse is a step voltage, which is then derived with respect to time and convolved with the applied signal to obtain the response of the measuring system. The step generator used for this purpose should have very fast front without oscillations. The intent is to achieve a close approximation of an ideal step function, which when derived with respect to time, yields the impulse response of a tested system. A necessary prerequisite is that the step is much steeper than the lightning impulse, and is flat after the step on times much longer than the impulse. The ideal switch element in such a step generator should have infinite resistance and zero capacitance in the off-state, very fast switching to on-state and very low resistance in on-state. The mercury wetted reed switch has often been used for this purpose since it has good characteristics in all these respects. Few, if any, electronic components exhibit competitive advantages compared to the reed switch. The relative lack of parasitic effects means that it is close to being an ideal device. Based on earlier experiences by the authors, a new design has been developed with focus on electrical screening and coaxial design in order to realise a step generator that works into a high impedance instrument. Considerable work has been performed to characterise the new device with regard to steepness of step and most importantly, to voltage stability after the step. The most demanding part of this work has been to separate the performance of the switch from that of the oscilloscope. Findings indicate that the step rise-time is less than 0.5 ns, and settling to within 0.5 % within 10 ns.

National Category
Other Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33480 (URN)
Conference
International Symposium on High-Voltage Engineering, 2017
Funder
European Metrology Programme for Innovation and Research (EMPIR), 14IND08
Available from: 2018-03-08 Created: 2018-03-08 Last updated: 2019-06-20Bibliographically approved
Bergman, A., Elg, A. P. & Hällström, J. (2017). Evaluation of step response of transient recorders for lightning impulse. In: : . Paper presented at International Symposium on High-Voltage Engineering,2017.
Open this publication in new window or tab >>Evaluation of step response of transient recorders for lightning impulse
2017 (English)Conference paper, Published paper (Refereed)
Abstract [en]

High voltage equipment will be subjected to several types of electrical stress during operation. A battery of factory tests is defined to ensure that the equipment will perform satisfactorily in service. One of the crucial tests is to apply a simulated lighting impulse as standardised to a double-exponential impulse with at front time of 1.2 µs (± 30 %) and a time to half value of 50 µs (± 20 %). Although this wave-shape only approximates natural lightning, there is a solid body of experience within industry, proving that reliability of equipment in service is adequately proven by the standard waveform. It is however crucial for consistency of results that the both voltage level and wave-shape are correctly measured. This paper discusses the requirements and performance of the recording instruments used, leaving the properties of high voltage impulse dividers outside the discussion. The requirements for the recording instrument – transient recorder – are given in IEC 61083-1. The standard provides requirements for, and/or tests to verify, that the recorder has moderately fast response, fast settling time, high resolution, linearity under dynamic conditions, high accuracy and reasonably low internal noise. This is partly in contrast to major trends in transient recorder development, where fast sampling and fast step response are prioritized ahead of high accuracy and fast settling without creeping response. We have therefore evaluated several commercially available recorders in order to find one with respectively flat and reasonably fast step response. In this campaign, a proprietary step generator based on the use of a mercury reed relay has been used. Evaluation of this device is submitted to ISH 2017. It has been found that the measured flatness of the step response directly after the step is a good first indicator of the performance of the transient recorder. This is identified in IEC 61083-1 clauses 1.5.2 and 1.5.3, as a requirement on stability of the recorded step from 0.5 T1min to T2max. For lightning impulse this means from 0.42 µs to 60 µs. For approved transient recorders the requirement is to be within 1 %. For reference transient recorders, a limit of not more than 0.5 % should be applied. Further proof of the accuracy of the transient recorder can be achieved by convolution of an ideal waveform with the recorded step response and analysing the resulting curve with lightning impulse parameter software. A third possibility is to make direct calibration of the transient recorder, using a calculable impulse calibrator. Several state-of-art transient recorders have been evaluated and the results show that only a few are suited for measurement of lightning impulse. Also, the variation of the performance between the ranges and channels of one instruments are significantly large. Both direct assessment of step response as well as result of convolution with a theoretical 0.84/50 µs impulse will be reported. The agreement with results obtained with a calculable impulse calibrator will be illustrated.

National Category
Other Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33398 (URN)
Conference
International Symposium on High-Voltage Engineering,2017
Funder
European Metrology Programme for Innovation and Research (EMPIR), 14IND08
Available from: 2018-03-08 Created: 2018-03-08 Last updated: 2019-06-20Bibliographically approved
Larzelere, W., Hällström, J., Elg, A. P., Bergman, A., Kluss, J., Li, Y. & Zhou, L. (2017). MEASUREMENT OF THE INTERNAL INDUCTANCE OF IMPULSEVOLTAGE GENERATORS AND THE LIMITS OF LI FRONT TIMES. In: : . Paper presented at The 20th International Symposium on High Voltage Engineering, Buenos Aires, Argentina, August 27 – September 01, 2017.
Open this publication in new window or tab >>MEASUREMENT OF THE INTERNAL INDUCTANCE OF IMPULSEVOLTAGE GENERATORS AND THE LIMITS OF LI FRONT TIMES
Show others...
2017 (English)Conference paper, Published paper (Refereed)
Abstract [en]

The recent push to higher testing voltages for research and production tests onUHV system components rated above 800kV class has led to difficulties in achieving thestandard waveshapes as required by IEC60060 Parts 1 and 2 and other existing IEC,IEEE/ANSI and other standards. One of the limiting components in achieving themaximum capacitive loading on an impulse generator for standard lightning impulse fronttimes is the inductance of the circuit. The total inductance of the circuit is comprised ofthe internal inductance of the impulse generator and the inductance of the loop toconnect to the load. The higher the voltage class of test objects, the larger the loop,yielding more inductance that in turn, reduces the test capacitance that can be connectedand still remain inside the overshoot requirements of the standards. The internalinductance of the impulse generator is comprised of the wiring of the stages and thestage capacitor inductance and/or the inductance of the waveshaping resistors. Thispaper shows the results of methods to measure and calculate the internal inductance ofseveral impulse generators and we review the formulas for calculating the maximum loadof an impulse generator with a given internal inductance. We believe these methods givemore realistic values than adding up nameplate inductance values from an impulsegenerator. The paper also reviews the pros and cons of higher stage capacitances inimpulse generators to test larger loads that are ultimately limited by the circuit inductancevalue. The intent of this paper is to assist in the revision of future IEC and IEEE standardsfor impulse testing apparatus in the UHV range

National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33390 (URN)
Conference
The 20th International Symposium on High Voltage Engineering, Buenos Aires, Argentina, August 27 – September 01, 2017
Available from: 2018-03-07 Created: 2018-03-07 Last updated: 2019-06-20Bibliographically approved
Klüss, J., Hällström, J. & Elg, A. P. (2015). Optimization of field grading for a 1000 KV wide-band voltage divider (ed.). Journal of Electrostatics, 73, 140-150
Open this publication in new window or tab >>Optimization of field grading for a 1000 KV wide-band voltage divider
2015 (English)In: Journal of Electrostatics, ISSN 0304-3886, E-ISSN 1873-5738, Vol. 73, p. 140-150Article in journal (Refereed) Published
Abstract [en]

An HVDC reference voltage divider has been designed for high accuracy and wide-band measurements up to 1000 kV. To maintain wide-band characteristics, field distribution must be optimized in order to minimize the response time of the divider. To compensate the stray capacitance, a capacitive path that surrounds the resistive reference divider is added to function as a shield. Optimal capacitance values producing a matched distribution are obtained using 3D FEM simulations. Factors affecting the performance of the divider are assessed by simulating multiple scenarios representing different practical considerations in real-life applications.

Keywords
HVDC transmission, Electromagnetic fields, Finite element methods, Voltage dividers, Voltage measurement
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-6813 (URN)10.1016/j.elstat.2014.11.005 (DOI)23607 (Local ID)23607 (Archive number)23607 (OAI)
Available from: 2016-09-08 Created: 2016-09-08 Last updated: 2019-07-08Bibliographically approved
Hällström, J., Bergman, A., Dedeoğlu, S., Elg, A. P., Houtzager, E., Klüss, J., . . . Weber, C. (2015). Performance of a Modular Wideband HVDC Reference Divider for Voltages up to 1000 kV. IEEE Transactions on Instrumentation and Measurement, 64(6), 1390-1397, Article ID 7063966.
Open this publication in new window or tab >>Performance of a Modular Wideband HVDC Reference Divider for Voltages up to 1000 kV
Show others...
2015 (English)In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 64, no 6, p. 1390-1397, article id 7063966Article in journal (Refereed) Published
Abstract [en]

This paper describes the design and performance of a modular wideband high-voltage dc (HVDC) reference divider with a ratio uncertainty of less than 0.005% at 1000 kV. The divider has a maximum nominal voltage of 1000 kV when five 200-kV modules are stacked on top of each other. The divider is used for traceable calibration of HVDC measuring systems in customers' laboratories. The first priority in the design was the accuracy of HVDC measurements. In addition, the divider was designed to have wide bandwidth, both to enable measurement of ripple voltages and to prevent damage during possible flashovers.

Keywords
High-voltage dc (HVDC) transmission, high-voltage techniques, measurement standards, uncertainty, voltage dividers, HVDC power transmission, Uncertainty analysis, High voltage DC (HVDC), High voltage dc (HVDC) transmissions, High voltage techniques, Measuring systems, Nominal voltage, Traceable calibration
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:ri:diva-32452 (URN)10.1109/TIM.2015.2408795 (DOI)2-s2.0-85028224921 (Scopus ID)
Available from: 2017-11-03 Created: 2017-11-03 Last updated: 2019-07-08Bibliographically approved
Elg, A. P., Bergman, A., Hällström, J., Kharezy, M. & Nieminen, T. (2015). Traceability and Characterization of a 1000 kV HVDC Reference Divider. IEEE Transactions on Instrumentation and Measurement, 64(6), 1709-1715, Article ID 7100891.
Open this publication in new window or tab >>Traceability and Characterization of a 1000 kV HVDC Reference Divider
Show others...
2015 (English)In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 64, no 6, p. 1709-1715, article id 7100891Article in journal (Refereed) Published
Abstract [en]

This paper presents the characterization of a resistive high-voltage dc (HVDC) reference divider and methods to establish traceability. The divider is designed for use as a laboratory reference for calibration of HVDC measuring systems up to 1000 kV. Targeting a measurement uncertainty of 20 μV/V at full voltage has put a focus on the temperature coefficients of the resistors, elimination of humidity dependence, and control of leakage currents in the high-voltage arm. A scale factor calibration against a 50 kV divider at 10 kV leads to an expanded uncertainty of 15 μV/V.

Keywords
High-voltage dc (HVDC) transmission, high-voltage techniques, measurement standards, uncertainty, voltage dividers, Calibration, Humidity control, HVDC power transmission, Leakage currents, Uncertainty analysis, High voltage DC (HVDC), High voltage dc (HVDC) transmissions, High voltage techniques, Measurement uncertainty, Measuring systems, Temperature coefficient
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:ri:diva-32451 (URN)10.1109/TIM.2015.2410373 (DOI)2-s2.0-85027955466 (Scopus ID)
Available from: 2017-11-03 Created: 2017-11-03 Last updated: 2019-07-09Bibliographically approved
Hammarqvist, M., Elg, A. P., Bergman, A., Wolbert, J., Blennow, J. & Gubanski, S. M. (2014). Improvement of frequency response for a zero-flux current measuring system. In: CPEM Digest (Conference on Precision Electromagnetic Measurements): . Paper presented at 29th Conference on Precision Electromagnetic Measurements, CPEM 2014, 24 August 2014 through 29 August 2014 (pp. 618-619).
Open this publication in new window or tab >>Improvement of frequency response for a zero-flux current measuring system
Show others...
2014 (English)In: CPEM Digest (Conference on Precision Electromagnetic Measurements), 2014, p. 618-619Conference paper, Published paper (Refereed)
Abstract [en]

Magnetic zero-flux current transformers are widely utilized to measure AC and DC electrical currents. To improve the AC characteristics between 10 Hz and 100 kHz, a method is proposed to evaluate adjustments in the circuitry; increase of the amplification in the AC feed-back circuit and introduction of an external coaxial read-out shunt resistor. The method is generally applicable and includes a coaxial current path within the entire reference system and traceability to national standards. The AC working range is extended from about 1 kHz to about 3 kHz. Outside the nominal AC working range, the scale factor variation is reduced from 45 % to 3.5% and the phase angle error offset changes from ca 5.8 μs to below 0.3 μs. © 2014 IEEE.

Keywords
AC current, current transformer, frequency response, measurement technique, traceability, zero-flux, AC currents, Measurement techniques, Measuring systems, Electric instrument transformers
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:ri:diva-32457 (URN)10.1109/CPEM.2014.6898537 (DOI)2-s2.0-84907895873 (Scopus ID)9781479952052 (ISBN)
Conference
29th Conference on Precision Electromagnetic Measurements, CPEM 2014, 24 August 2014 through 29 August 2014
Available from: 2017-11-03 Created: 2017-11-03 Last updated: 2019-06-20Bibliographically approved
Wright, P., Bergman, A., Elg, A. P., Flood, M., Clarkson, P. & Herzberg, K. (2014). Onsite Measurements for Power-Quality Estimation at the Sweden - Poland HVDC Link (ed.). IEEE Transactions on Power Delivery, 29(1), 472-479
Open this publication in new window or tab >>Onsite Measurements for Power-Quality Estimation at the Sweden - Poland HVDC Link
Show others...
2014 (English)In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 29, no 1, p. 472-479Article in journal (Refereed) Published
Abstract [en]

A discussion of the power-quality (PQ) aspects of HVDC systems is given, in particular, harmonic aspects. This is followed by a description of the apparatus and their installation as part of an onsite measurement campaign at the Sternö;, classical HVDC station on the SwePol HVDC link. PQ results are presented, including the current and voltage characteristics of the station, converter harmonics, filtered harmonics, noncharacteristic harmonics, switch-on current, and system unbalance.

National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-6645 (URN)10.1109/tpwrd.2013.2276408 (DOI)19006 (Local ID)19006 (Archive number)19006 (OAI)
Available from: 2016-09-08 Created: 2016-09-08 Last updated: 2019-06-20Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5044-8266

Search in DiVA

Show all publications
v. 2.35.7