Optimization method for geometric shape of DC GIL insulators based on electric thermal multi-physics field coupling model

The excessive electric field on the surface of DC gas-insulated metal-enclosed transmission lines (GIL) basin insulators is one of the main factors leading to insulation failure. In this paper, we parameterized and reconstructed the shape of the insulator based on the Bernstein polynomial under the Bessel curve and established an optimization model for the geometric shape of 500 kV DC GIL insulators considering the surface charge accumulated on the insulator under temperature gradient. We obtained the optimal parameters of the contour function of the basin insulator surface using the Levenberg–Marquardt optimization algorithm and explored the optimization effect of insulators by the insulation tests. The results show that the optimized basin insulator has a maximum electrical strength of 4.39 kV/mm along the insulator surface, and the flashover voltage of the optimized insulator is 15.37% higher than that of the original structure, laying a foundation for the production of a new type of high-electrical performance basin insulator.