Suppression Mechanism of TiO2 for the Partial Discharge of Oil-paper Insulation in Intensive Electric Field

Abstract

With the rapid development of modern HVDC transmission technology, higher insulation properties are put forward on the oil-paper insulation system of the transformer, which determine the transformer service life to a certain extent. Traditional transformer oil-paper insulation is becoming increasingly difficult to meet the demands of insulation system with large capacity and miniaturization at ultra-high voltage level. In order to improve the insulation strength of oil-paper system, the insulation cellulose paper modified by TiO 2 nanoparticles of different diameters (5 nm, 10 nm, 20 nm, 30 nm) were prepared, in addition, each of modified cellulose paper has different mass fraction of TiO 2 nanoparticles (1%, 3%, 5%, 7% wt.). The partial discharge (PD) detection platform was established, and the partial discharge inception voltage (PDIV) values of the oil-paper insulation system with and without nanoparticles were measured. To investigate the PD characteristics, the PD waveforms and PD frequency spectrums of modified cellulose paper and the unmodified were obtained. The suppression mechanism of TiO 2 nanoparticles on PD was explored through scanning electron microscope (SEM) observation. All the experiment results indicate that adding nano-TiO 2 is beneficial to enhance the insulation properties of oil-paper insulation, and the optimum diameter and mass fraction of TiO 2 nanoparticles to suppress oil-paper PD were obtained.