直流电压下TiO_(2)纳米改性变压器油中电晕放电特性及机理  

Characteristics and Mechanism of Corona Discharge in Transformer Oil Modified by TiO_(2) Nanoparticles Under DC Voltage

作　　者：牛铭康 刘柏欣 吴延宇 宋翰林 黄猛 吕玉珍[2] NIU Mingkang;LIU Baixin;WU Yanyu;SONG Hanlin;HUANG Meng;LÜYuzhen(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources,North China Electric Power University,Beijing 102206,China;School of Energy Power and Mechanical Engineering,North China Electric Power University,Beijing 102206,China)

机构地区：[1]华北电力大学新能源电力系统国家重点实验室,北京102206 [2]华北电力大学能源动力与机械工程学院,北京102206

出　　处：《高电压技术》2021年第3期1037-1045,共9页High Voltage Engineering

基　　金：国家自然科学基金(51807062);国家重点研发计划(2017YFB0902704)。

摘　　要：电晕放电作为变压器油中局部放电主要形式之一,危害换流变压器的安全运行。纳米改性可以提高变压器油的绝缘性能,但直流电压下电晕放电的改性效果和机理研究不足。为此制备了二氧化钛纳米改性变压器油,采用针板缺陷进行了电晕放电过程中的图像拍摄、脉冲电流及光脉冲的测量,并测量了油中的电荷输运特性。研究发现,负极性直流电压下,纳米变压器油的击穿电压提高了23.8%;电晕放电强度也明显降低:外施电压50 kV时,纳米变压器油中电晕发光面积减小了86.0%,光脉冲和电流脉冲的频率分别减小75.6%和76.3%,幅值分别减小92.8%和78.6%。纳米粒子抑制电晕放电是因为纳米粒子向变压器油中引入更多浅陷阱促使电子从电离区逃脱,同时其极化捕捉作用削弱了电子碰撞电离,抑制了电子崩起始;此外带负电的纳米粒子的形成相当于增加了负离子数量、降低了其迁移率,从而降低了针尖处电场强度。该研究可为直流电压下变压器油电晕放电的抑制方法和纳米粒子的选型提供依据。As the main form of partial discharge in transformer oil, corona discharge will endanger the safe operation of converter transformer. The insulation performance of transformer oil can be improved by nano-modification. However, the research on the modification effect and mechanism of corona discharge under DC voltage is insufficient. Therefore, transformer oil modified by Ti O2 nanoparticles was prepared. Then a series of experiments including corona discharge image shooting, measurement of pulse current and light pulse were carried out with needle-plate defects in nanofluids(NFs). And the charge transport characteristics in NFs were measured. The results show that the breakdown voltage of NFs is increased by 23.8% and the corona discharge is greatly inhibited under a negative DC voltage. Compared with pure oil in 50 kV, the corona luminous area in NFs is reduced by 86.0%. Meanwhile, the frequencies of the optical pulse and current pulse were reduced by 75.6% and 76.3%, respectively, and the amplitudes were reduced by 92.8% and 78.6%, respectively. The reason why nanoparticles inhibit corona discharge is that more shallow traps introduced by nanoparticles accelerate electrons escaping from the ionization region, and its polarization trapping effect weakens the impact ionization of electrons, inhibiting the initiation of electron avalanche. In addition, the formation of negatively charged nanoparticles is equivalent to increase the number and decrease the mobility of negative ions, reducing the electric field strength at the tip of needle. The research in this paper will provide guidance for the suppression method of DC corona discharge and the selection of nanoparticles in transformer oil.

关 键 词：纳米改性变压器油 直流电压 电晕放电 浅陷阱 极化捕捉 离子迁移率 

分 类 号：TM41[电气工程—电器]