Research On The Electrical Characteristics Of Transformer Oil Modified By Nanoparticle

With the increase of the voltage level in power system,how to improve the dielectric performance is a hot research topic in the area.Transformer oil is one of the most important insulating dielectric in power transformer because it plays a dual role in improving the heat transfer and insulating charaters of the system.Therefore,developing new transformer oil with excellent insulation properties means a lot to improve the safe operation level of transformer,and it is also very helpfull to decrease the size and weight of ultra-high voltage transformer.In order to improve the electrical and insulation performance of transformer oil,many scholars of home and abroad have finished related research of nanoparticles modified transformer oil.Based on this,this article selects nano-SiO2?nano-ZnO and nano-Al2O3 three kinds of nano materials,take advantage of nano modification technology,to study nanoparticles modified transformer oil with different particle content under the AC breakdown experiment?dielectric test and creeping discharge test of oil-immersed pressboard, this study aims at building the theoretical and practical basis of nano-modified transformer oil in actual application.The AC breakdown performance test are discussed with different kinds of nano-modified transformer oil,different nanoparticles size,different preparation methods,different electrode gap and different kinds of nano-modified transformer oil-paper insulation. The experimental results show that the AC breakdown performance of three kinds of nano-modified transformer oil is systematically improved;the AC breakdown performance of ultrasonic dispersion method is more effective than mechanical mixing method;the AC breakdown performance of 15 nm nano-SiO2-modified transformer oil is better than 30nm; the AC breakdown performance of long electrode gap is proved more obvious;the AC breakdown performance of three kinds of nano-modified transformer oil-paper insulation is systematically improved.Study on the influence of nanoparticle to the creeping discharge of pressboard in transformer oil,it is found that the carbide area of the surface of pressboard in nano-modified transformer oil in the same time is significantly smaller than without be modified.Dielectric properties test show that three kinds of nanoparticles can small amplitude increase the permittivity and obviously increase dielectric loss tangent of transformer oil.Both of them linearly increases with the nanoparticle content but the dielectric loss tangent exponentially increases with the temperature and the permittivity linearly decreases with the temperature.Based on Maxwell-Garnet equation and nanoparticles polarization theroy, we analyzed the improvement mechanism of the permittivity and dielectric loss tangent of nano-modified transformer oil.