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High frequency characteristics of medium voltage XLPE power cables
KTH, School of Electrical Engineering (EES).
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The response of a cable can be used to analyze the variation of the material characteristics along its length. For diagnosis of possible ageing, it is necessary to know how cable design, material properties and cable insulation ageing affects the wave propagation. A cable model has therefore been worked out based upon the high frequency properties of the cable insulation and conductor systems. The high frequency characteristics of the semi-conducting screens, new and water-tree aged cross-linked polyethylene (XLPE) insulation have been determined by two measuring techniques. Semi-conducting screens have a great influence on the attenuation of cables at high frequencies.

A dielectric function based on an empirical formula is fitted to the measured characteristics of the semi-conducting screens. The dielectric function is used in the cable model set-up to predict the propagation constant of the cables.

The high frequency characteristics of the water-tree degraded XLPE insulation obtained from measurements are related to the water content of the water trees of the samples. An effective materials model is developed to estimate the water content of the water trees and the conductivity of the water.

The propagation constant from the cable model is compared to the propagation constant obtained from measurements made on cables. Using approximate high frequency cable models, the relative contributions of the conductor and insulation systems to the attenuation and phase velocity of the cables are analyzed.

Place, publisher, year, edition, pages
Stockholm: KTH , 2005. , 93 p.
Series
Trita-ETS, ISSN 1650-674X ; 2005:17
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-560ISBN: 91-7178-215-X (print)OAI: oai:DiVA.org:kth-560DiVA: diva2:14437
Public defence
2005-12-20, Sal D2, Lindstedtsvägen 5, Stockholm, 10:15
Opponent
Supervisors
Note
QC 20101018Available from: 2005-12-14 Created: 2005-12-14 Last updated: 2010-10-18Bibliographically approved
List of papers
1. Measurement technique for high frequency characterization of semi-conducting materials in extruded cables
Open this publication in new window or tab >>Measurement technique for high frequency characterization of semi-conducting materials in extruded cables
2004 (English)In: IEEE transactions on dielectrics and electrical insulation, ISSN 1070-9878, E-ISSN 1558-4135, Vol. 11, no 3, 471-480 p.Article in journal (Refereed) Published
Abstract [en]

Knowledge on the dependence of wave propagation characteristics on material properties and cable design is important in establishing diagnostic methods for cable insulation. In this study, a high frequency measurement technique to characterize the semi-conducting screens in medium voltage cross-linked polyethylene (XLPE) cables has been developed. The frequency ranges from 30 kHz to 500 MHz. The influence of the experimental set-up, sample preparation methods, pressure and temperature are investigated. A dielectric function is developed for the semiconducting screens and this is incorporated into a high frequency model for the cable. The propagation characteristics obtained from the high frequency cable model are compared with those obtained from measurements made on the same cables.

Keyword
semi-conducting screen, semicon, geometric capacitance, admittance, complex permittivity, dielectric function, propagation constant, attenuation, high frequency cable model, scattering parameters, cross-linked polyethylene, XLPE, cables
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-23514 (URN)10.1109/TDEI.2004.1306725 (DOI)000222131200009 ()2-s2.0-3142685105 (Scopus ID)
Note
QC 20100525 QC 20111026Available from: 2010-08-10 Created: 2010-08-10 Last updated: 2017-12-12Bibliographically approved
2. Comparing two measurement techniques for high frequency characterization of power cable semi-conducting and insulating materials
Open this publication in new window or tab >>Comparing two measurement techniques for high frequency characterization of power cable semi-conducting and insulating materials
2006 (English)In: IEEE transactions on dielectrics and electrical insulation, ISSN 1070-9878, E-ISSN 1558-4135, Vol. 13, no 4, 712-716 p.Article in journal (Refereed) Published
Abstract [en]

Understanding the high frequency characteristics of the materials that make up medium voltage extruded cables is important in establishing diagnostics schemes based on electromagnetic pulse propagation methods. Two measurement techniques have been developed and used to characterize the high frequency material properties of semi-conducting screens and cross linked polyethylene (XLPE) insulation up to 100 MHz. The experimental details, parameter extraction and limitations of the two measurement techniques are presented.

Keyword
complex permittivity, scattering parameters, insulation, semi-conducting, two-port, one-port, high frequency, measurements, characterization
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-15913 (URN)10.1109/TDEI.2006.1667728 (DOI)000239705700004 ()2-s2.0-33748323309 (Scopus ID)
Note
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
3. High frequency characterization of the semi-conducting screens of medium voltage XLPE cables
Open this publication in new window or tab >>High frequency characterization of the semi-conducting screens of medium voltage XLPE cables
2002 (English)In: Electrical Insulation and Dielectric Phenomena, 2002 Annual Report Conference on, Cancun, 2002, 887-890 p.Conference paper, Published paper (Refereed)
Abstract [en]

In this study, a high frequency measurement technique to characterize the semi-conducting materials of the medium voltage XLPE cables in the frequency range of 30 kHz to 500 Mhz has been developed. The influence of the experimental set-up and the sample preparation methods are investigated. A dielectric response model is then developed for the semiconducting materials and this is incorporated into a model for the whole cable. The propagation characteristics obtained from the cable model are then compared with those obtained from measurements carried out on the actual XLPE cables.

Place, publisher, year, edition, pages
Cancun: , 2002
Keyword
Capacitance, Dielectric materials, Electric admittance, Electric potential, Permittivity, Semi-conducting screens, Electric cables
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-25302 (URN)10.1109/CEIDP.2002.1048937 (DOI)
Conference
2002 IEEE Conference on Electrical Insulation and Dielectric Phenomena; Cancun; 20 October 2002 through 24 October 2002
Note
QC 20101015Available from: 2010-10-15 Created: 2010-10-15 Last updated: 2010-10-18Bibliographically approved
4. High frequency characterization of medium voltage cables using time domain Reflectometry techniques
Open this publication in new window or tab >>High frequency characterization of medium voltage cables using time domain Reflectometry techniques
2001 (English)In: 17th Nordic Insulation Symposium(NORD-IS 01), Stockholm, Sweden, 2001, 211-218 p.Conference paper, Published paper (Refereed)
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-25298 (URN)
Conference
17th Nordic Insulation Symposium(NORD-IS 01), Stockholm, Sweden, 11/6-13/6
Note
QC 20101015Available from: 2010-10-15 Created: 2010-10-15 Last updated: 2010-10-18Bibliographically approved
5. Development of a measurement technique for high frequency characterization of insulation materials
Open this publication in new window or tab >>Development of a measurement technique for high frequency characterization of insulation materials
2004 (English)In: 2004 ANNUAL REPORT CONFERENCE ON ELECTRICAL INSULATION AND DIELECTRIC PHENOMENA, NEW YORK: IEEE , 2004, 206-209 p.Conference paper, Published paper (Refereed)
Abstract [en]

A technique to measure the high frequency characteristics of insulation materials has been developed. Using this technique, high frequency characteristics of known insulation materials have been obtained to check its accuracy. The test cell, measurement technique and the extraction of the relevant parameters from the measurements are discussed.

Place, publisher, year, edition, pages
NEW YORK: IEEE, 2004
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-25307 (URN)10.1109/CEIDP.2004.1364225 (DOI)000225187200049 ()2-s2.0-17744374481 (Scopus ID)0-7803-8584-5 (ISBN)
Conference
Annual Conference on Electrical Insulation and Dielectric Phenomena (CEIDP) Boulder, CO, OCT 17-20, 2004
Note
QC 20101015Available from: 2010-10-15 Created: 2010-10-15 Last updated: 2010-10-18Bibliographically approved
6. Dependence of XLPE insulated power cable wave propagation characteristics on design parameters
Open this publication in new window or tab >>Dependence of XLPE insulated power cable wave propagation characteristics on design parameters
2007 (English)In: IEEE transactions on dielectrics and electrical insulation, ISSN 1070-9878, E-ISSN 1558-4135, Vol. 14, no 2, 393-399 p.Article in journal (Refereed) Published
Abstract [en]

Propagation losses occur in medium voltage power cables as pulses propagate through them. Since cables have many components, these can make different contributions to the propagation losses. The relative contributions of the conductors, insulation and semi-conducting screens to the propagation characteristics of the cable are analyzed. The propagation characteristics of the cables are studied by a developed "approximate" model providing analytical expressions that can quantify the contributions to the losses by the different parts of the conductor and dielectric system. The model is compared with an "exact" model and is tested on four cables. © 2007 IEEE.

Keyword
Attenuation, Dielectric, High frequency, Insulation, Phase velocity, Propagation characteristics, Semi-conducting screens, Series impedance, Shunt admittance, Dielectric materials, Electric insulation, Electric potential, Parameter estimation, Electric cables
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-25308 (URN)10.1109/TDEI.2007.344619 (DOI)000245598900017 ()2-s2.0-34147119069 (Scopus ID)
Note
Tidigare titel: Modelling XLPE Insulated Power Cable Wave Propagation Characteristics(20101015) QC 20101015Available from: 2010-10-15 Created: 2010-10-15 Last updated: 2017-12-12Bibliographically approved
7. High frequency characteristics of water-tree degraded XLPE insulation in power cables
Open this publication in new window or tab >>High frequency characteristics of water-tree degraded XLPE insulation in power cables
2007 (English)In: IEEE transactions on dielectrics and electrical insulation, ISSN 1070-9878, E-ISSN 1558-4135, Vol. 14, no 5, 1271-1277 p.Article in journal (Refereed) Published
Abstract [en]

The high frequency characteristics, the complex permittivity in particular, of water-tree degraded XLPE insulation in power cables are determined using a two port measurement method. The insulation samples are obtained from both laboratory made samples and those from ex-service cables. The electrical measurements are related to the water tree content of the samples which is estimated by an optical method. An effective materials model is derived to help understand the observed characteristics. From the model it is possible to estimate the water content of the water tree and the conductivity of the water. There is a considerable difference in the water tree characteristics between laboratory and service aged cables. The conductivity of the water in the water trees of service aged cables is much higher than that found in laboratory aged samples.

Keyword
cables, XLPE, permittivity, water tree, insulation, conductivity, model, high frequency, spherical, ellipsoid
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-17027 (URN)10.1109/TDEI.2007.4339488 (DOI)000250096400024 ()2-s2.0-35348890428 (Scopus ID)
Note
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved

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