半导体纳米粒子改性变压器油的绝缘性能及机制研究

磁性导电纳米粒子可以提高变压器油的导热和绝缘特性,但其分散性极易受到磁场的影响,不利于变压器油性能的改善。利用半导体纳米粒子对变压器油进行改性,测量了改性前后变压器油的工频击穿特性、雷电击穿特性和局部放电特性,可知半导体纳米粒子不仅可以使变压器油的工频和雷电击穿电压提高至未改性变压器油的1.2倍,而且可以改善变压器油的局部放电特性。由于现有的电子捕捉理论无法解释这种现象,利用热刺激电流(thermally stimulated current,TSC)法对改性前后变压器油中的陷阱特性进行了测试,结果表明:纳米粒子的加入增加了变压器油中的浅陷阱密度,提高了变压器油对电荷的消散和输运能力,从而能够改善变压器油的绝缘性能。

Insulating Property and Mechanism of Semiconducting Nanoparticles Modified Transformer Oils

Recently,conducting magnetic nanoparticles have been explored to improve the dielectric strength and cooling capability of transformer mineral oil.However,the dispersibility of magnetic nanoparticles in the oil is greatly influenced by the presence of the magnetic field.It is unfavorable for property improvement of transformer oil.One type of semiconducting nanoparticle was chosen to modify the transformer oil in this paper.AC and lightning impulse breakdown strength and partial discharge(PD) characteristics of oil samples before and after the modification were measured.It was found that semiconducting nanoparticles can increase both AC and lightning impulse breakdown voltage up to 1.2 times compared with pure oil.Meanwhile,the PD characteristic of the modified oil sample was also dramatically improved.The present electron scavenger theory has its limitation to explain this phenomenon.Based on the trap characteristics of both pure oil and nanoparticle modified oil measured by the thermally stimulation current(TSC) method,it was found that electron shallow trap density is greatly increased in nanofluids,resulting in the improvement of charge transport rate and breakdown performance compared to that of pure oil.