Hybrid numerical simulation of the generation and distribution characteristics of SF6 heavy particles under different DC PD energies

To investigate the decomposition law of SF 6 under negative direct current partial discharge (PD) at different energies, a SF 6 PD hybrid numerical model based on fluid dynamics and plasma chemical reaction models, in which 14 particle species and 24 chemical reactions are considered, is proposed. The effectiveness of the proposed model is validated with the current pulse waveform and the V– I discharge curve obtained by experiment. The influence of discharge energy on SF 6 PD characteristic quantities and SF 6 decomposition products is investigated with simulation and experiment. The results show that most of the discharge area of SF 6 is neutral, and the cation clouds only exist in the ionosphere (4.79–5 mm). With the increase in applied voltage, the electric field intensity of the needle plate gap does not increase completely and even decreases in some areas. Moreover, different from the traditional opinion, the generation of SO 2 F 2 under PD is mainly generated by the hydrolysis reaction of SOF 4 , which is formed by [SF 5 ], [SF 4 ], and [OH], [O]. The reaction path of [SF 2 ] with O 2 is not important. Thus, c(SO 2 F 2 )/ c(SOF 2 + SO 2 ) can be used as the energy characteristic component ratio because of its ability to represent the low-fluorine sulfide ratio n([SF 5 ])/ n([SF 4 ]).