Enhanced voltage distribution and breakdown strength performances of oil‐paper composite insulation by adding TiO ₂ nanoparticles

Abstract

Oil-paper composite insulation (OPCI) is used as the main insulation material in the converter transformer. However, the dielectric properties of insulating oil and oil-impregnated paper are markedly mismatched under direct current (DC) voltage, resulting in an unbalanced distribution of voltage, which is considered to be a major cause of large insulation margin but frequent failures. Therefore, it is necessary to adjust the voltage distribution in OPCI to enhance its breakdown strength. In this work, surface-treated TiO 2 nanoparticles were employed to modify OPCI. The polarisation current tests revealed that by changing the additive amount of nanoparticles, the polarisation intensities of both oil and oil-impregnated paper could be adjusted. Based on this, a model taking relaxation polarisations into full consideration was established to analyse the voltage distribution in OPCI and predict the optimal concentration. The prepared OPCI with the concentration of 0.02 g/L has desired balanced voltage distribution due to the influence of nanoparticles on interface charge, and therefore high breakdown strengths under both DC voltage and polarity reversal voltage, which can be increased by 22.6% at most. This work puts forward a novel idea to improve insulation property of OPCI and provides a reference for broader application of nanomaterial in power equipment. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

A simple method considering the synergetic effect of space charge and inhomogeneous material conductivity for DC electric field computation

“…It shows that the field strength in the paper is also 10 times of that in the oil, which agrees with the ratio of material resistivity. Then homo-polarity charge with a density of 0.2 C/m 3 is assumed to be injected from the electrodes and accumulated on both sides of all the paper layer [25,26], whose field distribution is calculated through the method in Equation ( 16), which is shown in Figure 4b and red line in Figure 4c. It shows that the presence of the space charge considerably intensifies the field strength in the paper layer, which brings a greater challenge to paper insulation.…”

Effect ofSiO2particle size scale on the electrical performance of epoxy‐based nonlinear conductive composite

“…The specific improvement is closely related to the micro nano oxides' type, doping content, shape, and surface modification. [7,[10][11][12][13][14][15] The effect of surface modification and doping content (2, 5, and 10 wt%) of nano SiO 2 (particle size of 10-20 nm) on the dielectric properties of nano SiO 2 /LDPE composites was investigated by the solution blending method by Lau. The surface-modified SiO 2 nanoparticles had better dispersion and better performance, and the longer the molecular chain of the silane coupling agent used for surface modification, the better the performance of the corresponding composite.…”

Synthesis of high‐purity mesoporous nanosilica microspheres from retired composite insulators based on orthogonal experiment

“…Additionally, NSMs (nanosilica microspheres) have broader application prospects and higher economic value than usual nanosilica because of their unique properties. On the one hand, it is generally considered that the dispersion of nanoparticles is the key to determine whether the performance of nanocomposite dielectrics can be improved [19][20][21][22][23]. Compared with irregular silica particles, nanospheres have better dispersion in the matrix, which can significantly increase the specific surface area of the particles and make the particlematrix interface overlap and separate, thus further improving the insulation performance of the material [24,25].…”