Design Method of DC Basin Insulator Based on Surface Contour Curve Optimization

The along-surface insulation of basin insulators within DC GIS/GIL systems presents a notable vulnerability, primarily due to the accumulation of charge on the insulator surface under DC electrical stress, leading to distinct differences in along-surface electric field distribution compared to AC conditions. Consequently, conventional AC insulator design standards are inadequate for DC basin insulators. Investigating novel optimization methodologies for DC GIS/GIL basin insulators holds significant significance in enhancing the insulation efficacy of DC pipeline transmission apparatus. This study, built upon the restrictive conditions of along-surface insulation design for 126 kV AC insulators, precisely delineates criteria for controlling the along-surface electric field magnitude of insulators under DC superimposed negative polarity impulse voltages. It establishes an evaluation model for the along-surface electric field of insulators, integrating considerations of charge accumulation and superimposed impulse voltage. Employing the Bernstein equation, the insulator's surface contour curve is meticulously fitted and reconstructed to elucidate the impact of geometric contour control parameters on the insulator's geometric structure. Targeting the minimization of along-surface tangential and normal electric fields on the convex and concave sides of the insulator, a particle swarm algorithm is deployed for the optimization of geometric contour control parameters. Ultimately, the study culminates in the establishment of the geometric structure of a novel ±100 kV DC basin insulator. The novel DC basin insulator exhibits a notable reduction in the maximum along-surface normal electric field by 37.2% and 29.1% on the convex and concave sides, respectively, and achieves a reduction of 7.9% and 11.6% in the maximum along-surface tangential electric field (Etmax) on the convex and concave sides, respectively. Furthermore, Etmax conforms to assessment criteria under DC superimposed lightning impulse voltage. This research provides valuable academic insights into the design of DC basin insulator geometric structures.