Numerical prediction of HVDC wall bushing flashover caused by uneven wetting

In this paper, a numerical model is developed to determine the critical flashover voltage of an unevenly wetted HVDC wall bushing, The electric field of a 600 kV HVDC wall bushing is calculated by using the Finite Element Method, and the E-field distribution, particularly that along the critical line, is used to determine the critical flashover voltage (CFO). The simulation results show that predicted critical flashover voltages agree well with experimental data in literature. Furthermore, various aspects of uneven wetting flashover phenomena are verified. The influence of the dry zone length, rain conductivity, air pressure as well as altitude on the critical flashover voltage are also investigated using the developed model. The results presented in this paper suggest that the proposed E-field based model is an effective-tool to evaluate the performance of an HVDC wall bushing