Study On The Influencing Factors Of Electrical Performance Of Oil-immersed Transformer Insulation Paper

The transformer is the core equipment in the power system,and as the heart-coil of the transformer,it is the hub of transformer transformation and transmission and distribution energy,and the coil turn insulation is the key.The stability of the oil-immersed insulation paper in insulation system is to ensure the normal operation of transformers.Insulating paper is a cross discipline in the field of electrical and materials.The study of insulating paper in China mainly focuses on the analysis of aging performance and the preparation of insulating paper with low dielectric constant.There is less research on the effect of its production process and its structure on electrical performance.Firstly,the untreated sulphate softwood pulp was used as a raw material to purify the pulp.When the amount of acid used in the purification process was1%,the conductivity of the pulp water extract was high and the pH was low.By improving the washing process and the magnesium salt treatment,the problem was solved.After the pulp treated with magnesium salt.The content of K⁺,Na⁺,and Ca²⁺in the insulating paper decreased,especially Na⁺,and the reduction range reached 71.4%.In addition,the AC breakdown strength of the insulating paper were also improved.Secondly,by comparing the performance of insulating papers at home and abroad,The tearing degree of foreign insulation paper was obviously higher,and the degree of detangling of fiber was also higher.The higher the beating degree,the lighter the beating pressure,and the better electrical performance of the insulation paper.The PFI mill beats the Walley beater.Combined beating improved the mechanical strength and electrical properties of the insulating paper while increasing the pulping efficiency.Thirdly,the effect of increasing the AC breakdown strength of insulating paper was not obvious with flax,cotton pulp and synthetic fibers.When the amount of Tencel fiber was 10%,the AC breakdown strength of the insulating paper was the largest.With the increase of the degree of fibrillation of the Tencel fiber,the AC breakdown strength of insulating paper increased.The reason was that the higher the degree of fibrillation of the Tencel fiber,the more obvious the intertwining phenomenon between the fibers.The fine fibers of the Tencel fiber entered the pores of the insulating paper and played a role in regulating the aperture of the insulating paper.The degree of beating of Tencel fiber increased from 15SR to 48°SR,the total pore volume of the paper decreased by 12.6%,the pore diameter decreased by 24.1%,the porosity decreased by 6.4%,and the tortuous rate increased by 33.2%.Finally,the greater the tightness of insulation paper,the higher the AC breakdown strength.The double-layer insulation paper could withstand higher voltage than single insulation paper.When the amount of PEO was 0.05%,the uniformity index and the AC breakdown strength of the insulation paper was the highest.The greater the number of sieves,the AC breakdown of the insulation paper.However,the higher the shorter fiber content,the lower the physical strength of the paper.Compared with R16,the handsheets of P70/R100 fiber fraction showed a 22%decrease in tensile strength,a 63%decrease in tear,and a 27%increase in the AC breakdown strength of insulating paper.