Solidification Dynamics of Silicone Oil and Electric Field Distribution Within Outdoor Cable Terminations Subjected to Cold Environments

Outdoor oil-filled cable terminations play an important role in power transmission and distribution networks, but their frequent explosions and disintegration accidents in cold environments pose great risks to the stable operation of power systems. In this study, an electric field-temperature multi-physical field simulation model was built based on 220 kV oil-filled cable termination. The dynamic solidification process of the insulating silicone oil was analyzed. It is found that the solidification of silicone oil is a temporal and spatial evolutionary process, which is closely related to the load current and the external environment. The solidification of filled and coated silicone oil will induce air gap defects, which will lead to different electric field distortion at different interfaces, especially at the stress cone/cable insulation interface. So the effects of different states of coated silicone oil on partial discharge at the interface are tested. Compared with the non-coating condition, solidification of coated silicone oil will aggravate partial discharge in cold environments, which is irreversible. The related results indicate the fault mechanism of oil-filled cable terminations subjected to cold environments and provide references for the selection of insulation materials and other measures to improve the reliability of cable terminations considering extreme environments.