Effects of electron migration and adsorption on the suppression of negative corona discharge in nanoparticle transformer oil: experiments and simulations

Abstract

SiO2 and TiO2 nanofluids (NFs for short) were prepared, and a series of DC corona discharge tests were carried out under needle-plate electrode on both NFs and base oil, using the luminous area and pulse current to characterize the negative corona discharge characteristics. The trap distribution characteristic as well as the mobilities of positive and negative ions of the two types of NFs and base oil were measured. A kind of new corona discharge simulation model was established, and the effects of shallow traps and electrons adsorbed by nanoparticles were considered in the simulation model. The corona discharge was simulated under the needle-plate electrode and the simulation results were compared with the corona discharge characteristics obtained from the tests. Furthermore, the effects of shallow trap and electron adsorbed by nanoparticles on space charge and electric field distribution as well as field ionization in transformer oil were analyzed respectively, revealing the mechanism that nanoparticles regulate the carrier migration process to suppress the negative corona discharge of transformer oil.