Abstract
Flashover accidents on high-voltage bushings frequently occur under extreme rainfall, which is generally attributed to the bridging of adjacent sheds by pendant drops, a result of the dynamic deformation of pendant drops. We numerically investigate the effects of the parameters of pendant drops and the electric field on the dynamic deformation of pendant drops on a 500 kV transformer bushing under extreme rainfall and verify the simulation results by artificial rain experiment. The dynamic deformation of pendant drops is described by solving the Navier-Stokes equations and using the level set method. The results show that the maximum length of the pendant drop increases with the increase in the initial diameter and the initial mass flow rate, respectively, but decreases under the electric field. The main influencing factor on the maximum length of the pendant drop alters with the variation of the initial diameter and the initial mass flow rate in the absence of the electric field, whereas the initial mass flow rate is the unique main influencing factor in the presence of the electric field. Furthermore, the variations of the maximum length and breakup time of the pendant drop are elucidated by the instability of the pendant drop.
Highlights
A host of flashover accidents on high-voltage bushings and post insulators occur under rain, which threatens power system security severely [1]
To explore the dynamic deformation of the pendant drop with the variation of di, the time-dependent deformation of the pendant drop is depicted in Fig. 6, wherein two representative cases, di = 5.00 mm and 9.00 mm, are shown
The dynamic deformation of pendant drops on 500 kV bushing sheds under extreme rainfall has been investigated by simulation
Summary
A host of flashover accidents on high-voltage bushings and post insulators occur under rain, which threatens power system security severely [1]. Pendant drops on the edge of insulator sheds play a pivotal role in the whole process of rain flashovers [3], owing to partial discharge and decrease in flashover voltage caused by pendant drops [4]. The bridging of adjacent sheds by pendant drops is generally considered to be a main reason for rain flashovers [5]. Pendant drops bridge adjacent sheds is a result of the dynamic deformation of pendant drops. The dynamic deformation of water droplets on the surface of composite insulator sheds has been studied extensively [6]–[10]. The dynamic deformation of pendant drops on the edge of insulator sheds has not been investigated, and it is significantly different from the dynamic deformation of water droplets on the surface of insulator sheds.
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