Measurement and simulation of partial discharge in oil-paper insulation under the combined AC–DC voltage

Abstract Depending on unique operation characteristics for voltage applied on valve side winding of the converter transformers, it is extraordinarily significant to study the partial discharge (PD) behavior with oil-paper insulation under combined AC–DC voltage. Therefore, this paper investigated PD inception characteristics by pulse current methods with needle-plate electrode system under combined AC–DC voltage. Furthermore, 3D electric field distributions versus combined AC–DC voltage in different ratios were calculated by Finite Element Analysis (FEA). An experimental conclusion was drew that AC partial discharge inception voltage (PDIV) in pure oil would decrease linearly with the DC component increasing but the inception voltage with oil-paper insulation appeared to be independent of DC voltage and dependent of AC voltage. And 3D electric field distribution deduced from simulation provided a supplementary proof on the experimental results. Moreover, high speed photography was used to capture emitted light produced by discharge, estimate streamer velocity (1.8 km/s) and record streamer initiation and propagation process in oil gap. Previous studies have shown that the prebreakdown phenomena involving the generation and propagation of vapor channels through the oil could be divided into a three-stage process.

[1]  Bo Li,et al.  Space charge phenomena in oil-paper insulation materials under high voltage direct current , 2009 .

[2]  P.S. Maruvada.  800-kV HVDC transmission systems , 2008, 2008 IEEE/PES Transmission and Distribution Conference and Exposition.

[3]  Hongyan Nie,et al.  Breakdown characteristics of converter transformer insulation under composite AC and DC voltage , 2009, 2009 IEEE 9th International Conference on the Properties and Applications of Dielectric Materials.

[4]  H. S. Endicott,et al.  Electrode Area Effect for the Impulse Breakdown of Transformer Oil , 1957, Transactions of the American Institute of Electrical Engineers. Part III: Power Apparatus and Systems.

[5]  L. Lundgaard,et al.  An experimental study on the effect of DC bias on streamer initiation and propagation in a dielectric liquid under impulse voltage , 2009, IEEE Transactions on Dielectrics and Electrical Insulation.

[6]  M. G. Say,et al.  Electrical Engineer's Reference Book , 1985 .

[7]  S. N. Moorching,et al.  Comparative evaluation of dielectric strength of paper-oil insulation under ac, dc, combined, composite ac/dc and impulse voltages , 1998, 1998 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (Cat. No.98CH36257).

[8]  Li Li-cheng.  Development of HVDC Transmission Technology and Its Role in Power Network in China , 2004 .

[9]  Y. X. Zhou,et al.  Gas generation characteristics of transformer oil under combined AC-DC voltages in the process of arcing , 2011, 2011 Annual Report Conference on Electrical Insulation and Dielectric Phenomena.

[10]  Lianwei Bao,et al.  Influences of Corrosive Sulfur on Copper Wires and Oil-Paper Insulation in Transformers , 2011 .

[11]  P. K. Watson,et al.  Electrostatic and Hydrodynamic Effects in the Electrical Breakdown of Liquid Dielectrics , 1984, IEEE Transactions on Electrical Insulation.

[12]  Wang Zhan-jie,et al.  Simulation of AC and DC Electric Field for 800 kV Grade High Voltage Disconnector , 2011 .

[13]  W. R. Wilson,et al.  A fundamental factor controlling the unit dielectric strength of oil [includes discussion] , 1953, Transactions of the American Institute of Electrical Engineers. Part III: Power Apparatus and Systems.

[14]  Yuanxiang Zhou,et al.  Pre-stressing effect on DC breakdown in low-density polyethylene , 2009 .

[15]  P. Morshuis,et al.  Partial discharges at DC voltage: their mechanism, detection and analysis , 2005, IEEE Transactions on Dielectrics and Electrical Insulation.

[16]  B. R. Andersen,et al.  HVDC transmission-opportunities and challenges , 2006 .

[17]  H. S. Endicott,et al.  Area Effect and Its Extremal Basis for the Electric Breakdown of Transformer Oil [includes discussion] , 1956, Transactions of the American Institute of Electrical Engineers. Part III: Power Apparatus and Systems.

[18]  A. Neuber,et al.  Bubble Dynamics and Channel Formation for Cathode Initiated Discharges in Transformer Oil , 2005, 2005 IEEE Pulsed Power Conference.

[19]  N. H. Ahmed,et al.  On-line partial discharge detection in transformer , 1998, Conference Record of the 1998 IEEE International Symposium on Electrical Insulation (Cat. No.98CH36239).

[20]  K. Wen,et al.  A calculation method and some features of transient field under polarity reversal voltage in HVDC insulation , 1993 .

[21]  C. Heitz.  A new stochastic model for partial discharge processes , 1998, 1998 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (Cat. No.98CH36257).

[22]  N. Bonifaci,et al.  Formation of vapor bubbles in nonpolar liquids initiated by current pulses , 1990, 10th International Conference on Conduction and Breakdown in Dielectric Liquids.

[23]  E. Kuffel,et al.  The volume and area effect in transformer oil , 2002, Conference Record of the the 2002 IEEE International Symposium on Electrical Insulation (Cat. No.02CH37316).

[24]  O. Lesaint,et al.  Streamer generation and propagation in transformer oil under divergent field conditions , 1987, 1987 Ninth International Conference on Conduction and Breakdown in Dielectric Liquids.

[25]  Y. Tsutsumi,et al.  Partial discharge characteristics of oil-immersed insulation systems under DC, combined AC-DC and DC reversed polarity voltage , 1976, IEEE Transactions on Power Apparatus and Systems.