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Understanding the Discharge Activities in Transformer Oil under AC and DC Voltage Adopting UHF Technique
Abstract:Design of Converter transformer insulation is a major challenge. The insulation of these transformers is stressed by both AC and DC voltages. Particle contamination is one of the major problems in insulation structures, as they generate partial discharges leading it to major failure of insulation. Similarly corona discharges occur in transformer insulation. This partial discharge due to particle movement / corona formation in insulation structure under different voltage wave shapes, are different. In the present study, UHF technique is adopted to understand the discharge activity and could be realized that the characteristics of UHF signal generated under low and high fields are different. In the case of corona generated signal, the frequency content of the UHF sensor output lies in the range 0.3-1.2 GHz and is not much varied except for its increase in magnitude of discharge with the increase in applied voltage. It is realized that the current signal injected due to partial discharges/corona is about 4ns duration measured for first one half cycle. Wavelet technique is adopted in the present study. It allows one to identify the frequency content present in the signal at different instant of time. The STD-MRA analysis helps one to identify the frequency band in which the energy content of the UHF signal is maximum.
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1070581Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF
 IEEE Trial use standard general requirements and test code for oil immersed HVDC converter transformers, IEEE Std C57.129-1999, IEEE USA.
 W. Kennedy, Recommended dielectric tests and test procedures for converter transformers and smoothing reactors, IEEE Trans. On Power Delivery, 1(3), (1986) pp161-166.
 R. Tobazeon, Behaviour of spherical and cylindrical particles in an insulating liquid subjected to a DC uniform field, Conduction and Breakdown in Dielectric Liquids,1993., ICDL '93., IEEE 11th International Conference on 19-23, PP.415 - 420, 1993.
 M.D. Judd, O. Farish and B.F. Hampton, Excitation of UHF signals by partial discharges in GIS, IEEE Trans. On dielectrics and electrical insulation, Vol-3, pp213-228, 1996.
 M.D. Judd, O. Farish and B.F. Hampton, Excitation of UHF signals by partial discharges in GIS, IEEE Trans. On dielectrics and electrical insulation, 3(2), (1996), pp213-228.
 G.P. Cleary and M.D. Judd, UHF and current pulse measurement of partial discharge activity in mineral oil, IEE Proc.- Sci. Meas. Technol. 153(2), (2006), pp47-54.
 A Cavallini, G.C. Montanari, F. Ciani, Analysis of partial discharge phenomena in paper oil insulation system as a basis for risk assessment evaluation, IEEE International Conference on Dielectric Liquids, pp241 - 244, 2005.
 A Convery and M D Judd, "Measurement of propagation characteristics for UHF signals in transformer insulation materials", Proc. 13th Int. Symp. on High Voltage Engineering (Delft), August 2003.
 M.D. Judd and O. Farish, A pulsed GTEM system for UHF sensor calibration, IEEE Trans. on Instrumentation and measurement, Vol-47, pp875-880, 1998.
 National Grid Company plc, Capacitive couplers for UHF partial discharge monitoring, Technical guidance note: TGN(T)121, Issue 1, Jan 1997.
 O. Rioul and M. Vetterli, Wavelet and Signal Processing, IEEE Signal Processing Magazine, pp. 14 - 38, 1991.
 Mallat, S. G., A Theory for Multi resolution signal decomposition: The wavelet representation. IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 11, No. 7 (1989), pp. 674- 693.
 A.M. Gaouda, M.M.A. Salama, M.R. Sultan and A.Y. Chikhani, Power Quality Detection and classification using Wavelet- Multi resolution Signal Decomposition, IEEE Trans. on Power delivery, Vol. 14, No. 4, pp. 1469 - 1476, 1999.
 M. Krins, H. Borsi and E. Gockenbach, Influence of carbon particle on the breakdown voltage of transformer oil,12th Int. conf. On conduction and breakdown in dielectric liquids (ICDL) Rome, Italy, pp296-299, 1996.
 S. Birlasekaran, The movement of a conductive particle in transformer oil in AC fields, IEEE Trans. on Electrical Insulation, 28(1), (1993), pp9-17.
 S. Birlasekaran, The measurement of charge on single particles in transformer oil, IEEE Trans. on Electrical Insulation, 26(6), (1991) pp1094-1103.
 Lucian Dascalescu, Michaela Mihaiescu, Robert Tobazeon, Modeling of conductive particle behavior in insulating fluids affected by DC electric fields, IEEE Trans. On Industry Applications, 34(1), (1998), pp66-74.
 M.D. Judd, Li Yang, Ian B.B. Hunter, Partial discharge monitoring for power transformers using UHF sensors Part-1: Sensors and signal interpretation, IEEE Electrical Insulation magazine, 21(2), (2005), pp5- 14.
 M.D. Judd, Li Yang, Ian B.B. Hunter, Partial discharge monitoring for power transformers using UHF sensors Part-2: Field Experience, IEEE Electrical Insulation Magazine, 21(3), (2005) 5-13.
 Sander Meijer, Edward Gulski, Johan J. Smit, H.F. Reijnders, sensitivity check for UHF Partial discharge detection in power transformers, Conf. Record of the 2004 IEEE int. conf. on Electrical Insulation, pp58-61, Sept. 2004, Indianapolis, USA.
 K. Raja and S. Lelaidier, Experience with UHF partial discharge measurement, Proc of 14th Int. conf. on dielectric liquids, pp239-241, 2002.