Study On Electrical And Dielectric Properties Of Gas-to-Liquid Transformer Oil

Transformer oil as an important liquid insulating material in the power system, the demand of the transformer oil increasing rapidly with the large-scale construction of electric power grid, especially the construction of the UHV AC/DC power grid. Due to the limitated reserves of the naphthenic base crude oil, the supply of the high grade naphthene base transformer oil is restricted, power grid construction and power equipment safe and stable operation are impacted becaues of the shortage of high quality of transformer oil.In recent years natural gas to liquid technology has made breakthrough progress, the synthetic transformer oil which produced from natural gas to liquid technology are beginning to enter the transformer oil market. GTL(Gas to Liquid) transformer oil as a new type of transformer oil, its various performance didn’t get a in-depth study, and the understanding about the GTL transformer oil is not comprehensive, so its necessary to get some in-depth study about the GTL transformer oil, and provide the corresponding theoretical basis for its application promotion.In this paper the structure, typical physical and chemical properties, electrical properties, mix oil properties and dielectric properties of GTL transformer oil have been researched. Two traditional naphthenic transformer oil and a tradition of non-naphthenic transformer oil in controlled trials at the same time.Experimental results show that GTL transformer oil is a naphthenic transformer oil which has high flash point, low density, low acid value and low total sulfur content. In terms of electrical performance, the performance of breakdown voltage and partial discharge characteristics are similar with the traditional transformer oil, and lightning impulse breakdown voltage is higher than the other three kinds of traditional transformer oil average value 16.47%. GTL transformer oil separately mixed with other three kinds of traditional transformer with the same volume, the dielectric loss, acid value, and pour point meet the GB/T 7595-2008 "in the operation of the transformer oil quality standards". In terms of dielectric properties, the real part of the dielectric constant of GTL transformer oil and oil-immersed insulation board is less than traditional naphthenic transformer oil, and the ratio between the real part of the dielectric constant of GTL transformer oil and oil-immersed insulation board is smaller than traditional naphthenic transformer oil; The imaginary part of the dielectric constant of GTL transformer oil under-10℃ and 20℃ condition is higher than than traditional naphthenic transformer oil at low frequencies, while at high frequencies, the imaginary part of the dielectric constant of GTL transformer oil is smaller than traditional naphthenic transformer oil, under 50℃ and 80℃ condition, the imaginary part of the dielectric constant of GTL transformer oil is similar with traditional naphthenic transformer oil. fitting the imaginary part of the dielectric constant accordance with H-N model, the fitting results shows that GTL transformer oil relaxation polarization time affected by the temperature is smaller than traditional naphthenic transformer oil.