Electrical Tree Growth Characteristics in Epoxy Resin With Harmonic Superimposed DC Voltage

HVDC converters can generate harmonic voltage, which distorts the DC voltage quality and threatens epoxy resin insulation reliability. In this paper, the electrical tree growth was investigated in epoxy resin under harmonic superimposed DC voltage. The DC voltage ranged from −20 to +20 kV and harmonic frequency ranged from 50 to 450 Hz. This experiment was carried out with needle-plate electrodes system. The effects of DC amplitude and harmonic order were characterized by electrical tree length and accumulated damage. Results show that the electrical tree varies with different combinations of DC amplitudes and harmonic orders. The tree length and accumulated damage experience a non-linear trend with the rise of harmonic order. The low-order harmonics bring more damage to epoxy resin under superimposed voltage. The time to breakdown shows a minimum value at 3rd harmonic superimposed voltage. The DC amplitude has an acceleration on the electrical treeing process. With higher DC amplitude, the electrical tree breakdown happens immediately when the electrical tree reaches the plate electrode. The charge transport process accounts for the tree initiation characteristics under different superimposed DC amplitudes and harmonic orders. Meanwhile, “reverse tree” has been found in epoxy resin sample. The field-driven tree growth model has been employed to interpret reverse tree growth from the perspective of dynamic electric field distribution.

[1]  G. Chen,et al.  Propagation mechanism of electrical tree in XLPE cable insulation by investigating a double electrical tree structure , 2008, IEEE Transactions on Dielectrics and Electrical Insulation.

[2]  H. R. Zeller,et al.  A fractal model of dielectric breakdown and prebreakdown in solid dielectrics , 1986 .

[3]  Toshikatsu Tanaka Space charge injected via interfaces and tree initiation in polymers , 2001 .

[4]  Y. Ohki,et al.  Frequency dependence of breakdown performance of XLPE with different artificial defects , 2012, IEEE Transactions on Dielectrics and Electrical Insulation.

[5]  S M Rowland,et al.  Investigating the impact of harmonics on the breakdown of epoxy resin through electrical tree growth , 2010, IEEE Transactions on Dielectrics and Electrical Insulation.

[6]  G. Teyssedre,et al.  Charge transport modeling in insulating polymers: from molecular to macroscopic scale , 2005, IEEE Transactions on Dielectrics and Electrical Insulation.

[7]  Shengtao Li,et al.  Space Charge Modulated Electrical Breakdown , 2016, Scientific Reports.

[8]  M. Ieda,et al.  DC Treeing Breakdown Associated with Space Charge Formation in Polyethylene , 1976, IEEE Transactions on Electrical Insulation.

[9]  B. X. Du,et al.  Effects of ambient temperature on electrical tree in epoxy resin under repetitive pulse voltage , 2017, IEEE Transactions on Dielectrics and Electrical Insulation.

[10]  Peng Liu,et al.  Design and dielectric characteristics of the ±1100 kV UHVDC wall bushing in china , 2015, IEEE Transactions on Dielectrics and Electrical Insulation.

[11]  T. Hibma,et al.  Direct measurement of space‐charge injection from a needle electrode into dielectrics , 1986 .

[12]  G. Chen,et al.  Electrical treeing characteristics in XLPE power cable insulation in frequency range between 20 and 500 Hz , 2009, IEEE Transactions on Dielectrics and Electrical Insulation.

[13]  J. H. Mason Breakdown of Solid Dielectrics in Divergent Fields , 1955 .

[14]  D. M. Hepburn,et al.  Influence of HVDC converter operation on partial discharge characteristics , 2016, 2016 IEEE International Power Modulator and High Voltage Conference (IPMHVC).

[15]  Tao Han,et al.  Electrical Tree Initiation and Growth in Silicone Rubber under Combined DC-Pulse Voltage , 2018 .

[16]  B. X. Du,et al.  Effect of pulse frequency on tree characteristics in epoxy resin under low temperature , 2016, IEEE Transactions on Dielectrics and Electrical Insulation.

[17]  J. V. Champion,et al.  Analysis and modelling of electrical tree growth in synthetic resins over a wide range of stressing voltage , 1994 .

[18]  Y. Sekii,et al.  DC tree and grounded DC tree in XLPE , 2005, CEIDP '05. 2005 Annual Report Conference on Electrical Insulation and Dielectric Phenomena, 2005..

[19]  Simon M. Rowland,et al.  Electrical treeing and reverse tree growth in an epoxy resin , 2017, IEEE Transactions on Dielectrics and Electrical Insulation.

[20]  M. Mammeri,et al.  Dynamics of voltage polarity reversal as the controlling factor in space-charge induced breakdown of insulating polymers , 1997 .

[21]  Y. Saito,et al.  On the Mechanism of Tree Initiation , 1977, IEEE Transactions on Electrical Insulation.

[22]  R. Yacamini,et al.  Harmonic transfer through converters and HVDC links , 1992 .

[23]  L. A. Dissado,et al.  The role of bulk charge transport processes in electrical tree formation and breakdown mechanisms in epoxy resins , 2016, IEEE Transactions on Dielectrics and Electrical Insulation.

[24]  J M Cooper,et al.  The influence of physical properties on electrical treeing in a cross-linked synthetic resin , 1990 .

[25]  L. A. Dissado,et al.  Effect of tree channel conductivity on electrical tree shape and breakdown in XLPE cable insulation samples , 2011, IEEE Transactions on Dielectrics and Electrical Insulation.

[26]  Toshikatsu Tanaka,et al.  Charge transfer and tree initiation in polyethylene subjected to AC voltage stress , 1992 .

[27]  Liu Ying,et al.  Electrical tree initiation in XLPE cable insulation by application of DC and impulse voltage , 2013, IEEE Transactions on Dielectrics and Electrical Insulation.

[28]  John C. Fothergill,et al.  Electrical degradation and breakdown in polymers , 1992 .

[29]  Murray Olyphant,et al.  Breakdown by Treeing in Epoxy Resins , 1963 .

[30]  B. X. Du,et al.  Tree initiation characteristics of epoxy resin in Ln2 for superconducting magnet insulation , 2015, IEEE Transactions on Dielectrics and Electrical Insulation.