Ghulam Murtaza HASHMI, Ruslan PAPAZYAN, Matti LEHTONEN

Determining wave propagation characteristics of MV XLPE power cable using time domain reflectometry technique

In this paper, the wave propagation characteristics of single-phase medium voltage (MV) cross-linked polyethylene (XLPE) power cable are determined using time domain reflectometry (TDR) measurement technique. TDR delivers the complex propagation constant (attenuation and phase constant) of lossy cable transmission line as a function of frequency. The frequency-dependent propagation velocity is also determined from the TDR measurements through the parameters extraction procedure. The calibration of the measuring system (MS) is carried-out to avoid the effect of multiple reflections on the accuracy of measurements. The results obtained from the measurements can be used to localize the discontinuities as well as the design of communication through distribution power cables.

Anahtar Kelimeler:

Cross-linked polyethylene, distribution power cables, time domain reflectometry, propagation constant, attenuation constant, phase constant, propagation velocity

Determining wave propagation characteristics of MV XLPE power cable using time domain reflectometry technique

Keywords:

Cross-linked polyethylene, distribution power cables, time domain reflectometry, propagation constant, attenuation constant, phase constant, propagation velocity,

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In the presented case the pulse width for the incident signal is 2 a = 12 ns (see Figure 5), so it could be expected that zero crossings and the respective numerical artefacts to be in the vicinity of f0= 81 MHz (for k = 1).
In this paper, the technique applied to extract frequency-dependent wave propagation characteristics has already been used in [11]. The TDR measurements given in [11] are taken in High Voltage Laboratory, which is free from external interferences. However, TDR measurements given in the presented paper have been taken in an ordinary place to simulate the situation with on-site measurements. A major bottleneck encountered with on-site TDR measurements is the ingress of external interferences that directly aﬀects the sensitivity and reliability of acquired data.
The TDR measurement technique has been presented to extract the frequency-dependent wave propagation characteristics of single-phase MV XLPE power cables in an ordinary environment. The calibration of the system corrects for the impedance mismatch at the MS/DUT interface by calculating the frequency-dependent reﬂection coeﬃcient at this point. The calibration additionally removes the symmetric errors from losses in the connecting cables of the MS, thus assuring TDR measurement is more accurate and reliable.
G. Mugala, “High Frequency Characteristics of Medium Voltage XLPE Power Cables,” Doctoral Thesis, The Royal Institute of Technology, (KTH), Stockholm, Sweden, December 2005.
R. Papazyan, “Techniques for Localization of Insulation Degradation along Medium-Voltage Power Cables,” Doc- toral Thesis, The Royal Institute of Technology, (KTH), Stockholm, Sweden, ISBN 91-7178-044-0, April 2005.
Froroth, “Home Access Communications – Panning out of the Alternatives,” Vattenfall and the Royal Institute of Technology (KTH), Stockholm, Sweden. Proceedings of the Telecom Power Europe, Conference, London (UK), October 27–28, 1998.
G. Mugala, R. Papazyan, P. Nakov, “High Frequency Characterization of Medium Voltage Cables using Time Domain Reﬂectometry Techniques,” Proceedings of 17thNordic Insulation Symposium on Electrical Insulation, NORD-IS’01, Stockholm, Sweden. pp. 211–218, June 11-13, 2001.
G. Mugala, R. Eriksson, “High Frequency Characteristics of a Shielded Medium Voltage XLPE Cable,” Proceedings of Conference on Electrical Insulation and Dielectric phenomena, CEIDP’2001, pp. 132–136, October 2001.
G. C. Stone, S.A. Boggs, “Propagation of Partial Discharge Pulses in Shielded Power Cables,” Proceedings of Conference on Electrical Insulation and Dielectric phenomena, CEIDP’82, pp.275–280, October 1982.
D. K. Cheng, Field and Wave Electromagnetics, 2ndedition, Addison Wesley Publishing Company, Inc., 1989, pp. 449–471.
H. Meng, S. Chen, Y. L. Guan, C. L. Law, P. L. So, E. Gunawan, T. T. Lie, “A Transmission Line Model for High-Frequency Power Line Communication Channel,” Proceedings of International Conference on Power System Technology (PowerCon 2002), Kunming, China, October 13-17, 2002, pp. 1290–1295.
R. Papazyan, “Study on Localisation of Water Degraded Regions along Power Cable Insulation using Time Domain Reﬂectometry,” The Royal Institute of Technology, Master thesis No. 23030/3 2000.
G. M. Hashmi “Determination of Propagation Constants of Three Phase MV Cables using Time Domain Reﬂec- tometry,” Masters Thesis Work, The Royal Institute of Technology, (KTH), Stockholm, Sweden, Feb. 2001.
R. Papazyan, R. Eriksson, “Calibration for Time Domain Propagation Constant Measurements on Power Cables,” IEEE Transaction on Instrumentation and Measurement, Vol. 52, No. 2, pp. 415–418, April 2003.
L. R˚ade, B. Westergren, Mathematics Handbook for Science and Engineering, 3rdedition, Chartwell-Bratt, 1995, pp. 312.