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Electromagnetic dispersion modeling and measurements for HVDC power cables
Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
Jönköping University.
Gebze Institute of Technology, Gebze, Kocaeli, Turkey.
Lund University.
Visa övriga samt affilieringar
2014 (Engelska)Ingår i: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 29, nr 6, s. 2439-2447Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

This paper provides a general framework for electromagnetic (EM) modeling, sensitivity analysis, computation, and measurements regarding the wave propagation characteristics of high-voltage direct-current (HVDC) power cables. The modeling is motivated by the potential use with transient analysis, partial-discharge measurements, fault localization and monitoring, and is focused on very long (10 km or more) HVDC power cables with transients propagating in the low-frequency regime of about 0-100 kHz. An exact dispersion relation is formulated together with a discussion on practical aspects regarding the computation of the propagation constant. Experimental time-domain measurement data from an 80-km-long HVDC power cable are used to validate the electromagnetic model, and a mismatch calibration procedure is devised to account for the connection between the measurement equipment and the cable. Quantitative sensitivity analysis is devised to study the impact of parameter uncertainty on wave propagation characteristics. The sensitivity analysis can be used to study how material choices affect the propagation characteristics, and to indicate which material parameters need to be identified accurately in order to achieve accurate fault localization. The analysis shows that the sensitivity of the propagation constant due to a change in the conductivity in the three metallic layers (the inner conductor, the intermediate lead shield, and the outer steel armor) is comparable to the sensitivity with respect to the permittivity of the insulating layer. Hence, proper modeling of the EM fields inside the metallic layers is crucial in the low-frequency regime of 0-100 kHz.

Ort, förlag, år, upplaga, sidor
IEEE Press, 2014. Vol. 29, nr 6, s. 2439-2447
Nationell ämneskategori
Signalbehandling
Forskningsämne
Fysik, Vågor och signaler
Identifikatorer
URN: urn:nbn:se:lnu:diva-27494DOI: 10.1109/TPWRD.2014.2324181ISI: 000345513600003Scopus ID: 2-s2.0-84913596312OAI: oai:DiVA.org:lnu-27494DiVA, id: diva2:636314
Tillgänglig från: 2013-07-09 Skapad: 2013-07-09 Senast uppdaterad: 2017-12-06Bibliografiskt granskad
Ingår i avhandling
1. Electromagnetic dispersion modeling and analysis for HVDC power cables
Öppna denna publikation i ny flik eller fönster >>Electromagnetic dispersion modeling and analysis for HVDC power cables
2012 (Engelska)Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Derivation of an electromagnetic model, regarding the wave propagation in a very long (10 km or more) High Voltage Direct Current (HVDC) power cable, is the central part of this thesis. With an existing “perfect” electromagnetic model there are potentially a wide range of applications.The electromagnetic model is focused on frequencies between 0 and 100 kHz since higher frequencies essentially will be attenuated. An exact dispersion relation is formulated and the propagation constant is computed numerically. The dominating mode is the first Transversal Magnetic (TM) mode of order zero, denoted TM01, which is also referred to as the quasi-TEM mode. A comparison is made with the second propagating TM mode of order zero denoted TM02. The electromagnetic model is verified against real time data from Time Domain Reflection (TDR) measurements on a HVDC power cable. A mismatch calibration procedure is performed due to matching difficulties between the TDR measurement equipment and the power cable regarding the single-mode transmission line model.An example of power cable length measurements is addressed, which reveals that with a “perfect” model the length of an 80 km long power cable could be estimated to an accuracy of a few centimeters. With the present model the accuracy can be estimated to approximately 100 m.In order to understand the low-frequency wave propagation characteristics, an exact asymptotic analysis is performed. It is shown that the behavior of the propagation constant is governed by a square root of the complex frequency in the lowfrequency domain. This thesis also focuses on an analysis regarding the sensitivity of the propagation constant with respect to some of the electric parameters in the model. Variables of interest when performing the parameter sensitivity study are the real relative permittivityand the conductivity.

Ort, förlag, år, upplaga, sidor
Växjö: , 2012. s. 10
Nyckelord
HVDC power cables, electromagnetic model, TDR measurement, sensitivity analysis, dispersion relation, propagation constant, low-frequency asymptotics
Nationell ämneskategori
Annan fysik
Identifikatorer
urn:nbn:se:lnu:diva-32525 (URN)
Presentation
2012-12-11, D1136, Växjö, 13:15 (Engelska)
Opponent
Handledare
Tillgänglig från: 2014-08-19 Skapad: 2014-02-27 Senast uppdaterad: 2014-08-19Bibliografiskt granskad
2. Electromagnetic Dispersion Modeling and Analysis for Power Cables
Öppna denna publikation i ny flik eller fönster >>Electromagnetic Dispersion Modeling and Analysis for Power Cables
2014 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

This thesis addresses electromagnetic wave propagation in power cables. It consists of five papers, where the three first papers are based on one and the same model, and the last two papers are based on a similar but slightly different model. The first model considers electromagnetic modeling in connection with basic transmission line theory with a mismatch calibration of the scattering parameters, while the second model is based on a magnetic frill generator with calibration on the input current.

The two models describe the dispersion characteristics of an 82 km long High Voltage Direct Current (HVDC) power cable, and the results are validated with Time Domain Reflectometry (TDR) measurements. In both models the relevant bandwidth is 100 kHz, with the result that the fields inside the metallic layers must be calculated due to a large skin-depth. The present study is concerned with Transversal Magnetic (TM) modes of order zero. Higher order TM modes, including the Transversal Electric (TE) modes, will essentially be cut-off in this low-frequency regime.

An asymptotic analysis regarding the low-frequency dispersion characteristics is provided in Paper I. Comparing the result with a numerical solution shows that the low-frequency characteristics of the power cable is complicated, and an asymptotic solution is only valid at frequencies below 1 Hz.

Paper II presents a sensitivity analysis of the propagation constant. It is concluded that some of the electrical parameters of the metallic layers, and of the insulating layer, have a large impact on the model, while other parameters do not perturb the model in any substantial way.

In Paper III a general framework for the electromagnetic modeling is provided. The paper addresses sensitivity analysis, computation, and measurements regarding wave propagation characteristics in power cables.

The asymptotic behavior of the non-discrete radiating mode, the branch-cut, is presented in Paper IV. The result is compared with the first and second propagating Transversal Magnetic (TM) mode.

Finally, Paper V addresses the numerical problems associated with large arguments in the Bessel functions, which are due to the large conductivity parameters of the metallic layers. The introduction of a perfect electric conductor (PEC) and a short illustration of an inverse problem are also discussed in the paper. At the end an analysis is presented regarding uncertainties in the model parameters, which shows that temperature is an important parameter to consider.

 

Ort, förlag, år, upplaga, sidor
Växjö: Linnaeus University Press, 2014
Serie
Linnaeus University Dissertations ; 182/2014
Nyckelord
power cable, electromagnetic model, dispersion relation, asymptotic analysis, sensitivity analysis
Nationell ämneskategori
Fysik
Identifikatorer
urn:nbn:se:lnu:diva-40651 (URN)978-91-87925-07-8 (ISBN)
Disputation
2014-10-23, D1136, Växjö, 10:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2015-04-28 Skapad: 2015-03-07 Senast uppdaterad: 2015-04-28Bibliografiskt granskad

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