微水含量对老化后变压器油介电性能影响分析

Analysis of Influence of Moisture Content Ondielectric Properties of Transformer Oil after Aging

变压器油是油浸式电力变压器中重要的液体绝缘介质,有灭弧、绝缘、冷却等作用。但国内外多年的研究表明变压器油是油浸式电力变压器内部绝缘性能最薄弱的环节,因此其绝缘性能直接决定了电力变压器能否正常安全的运行。为了探寻老化过程中微水对变压器油介电性能的影响,以45号变压器油为研究对象,利用自行搭建的频域介电谱测试平台以及载流子迁移率测试平台,得到了变压器油水分含量对其介电损耗因数、复介电常数实部、载流子迁移率的影响规律。研究结果表明:变压器油含水量增加时,其介电损耗因数、载流子迁移率和直流电导率均有所增大;在低频范围内,复介电常数实部会随着水分含量的增加而增加,并且频率越低增加的越大;在高频范围内,介电损耗因数曲线上的拐点会随着水分含量的增加逐渐消失;随着老化程度的加剧,变压器油的直流电导率增大的速率随含水率的增加而增加。

Transformer oil is an important liquid insulating medium in oil-immersed power transformers,which has the functions of arc extinguishing,insulation and cooling.However,many years of domestic and foreign researches have shown that transformer oil is the weakest link in the insulation of oil-immersed power transformers.Therefore,its insulation performance directly determines whether the power transformer can operate normally and safely.In order to explore the influence of moisture on the dielectric properties of transformer oil during the aging process,the 45#transformer oil is taken as the research object.The self-built frequency domain dielectric spectrum test platform and carrier mobility test platform were used to obtain the influence of the moisture content of the transformer oil on its dielectric loss factor,real dielectric constant real part and carrier mobility.The results show that the dielectric loss factor,carrier mobility and DC conductivity increase when the water content of the transformer oil increases.In the low frequency range,the real part of the complex permittivity increases with the moisture content increasing.And the lower the frequency,the greater the real part of the complex permittivity increases.In the high frequency range,the inflection point which appears on the dielectric loss factor curve will gradually disappear with the increase of moisture content.As the degree of aging increases,the increasing rate of DC conductivity of the transformer oil increases with the water content increasing.