## 2 Establishment and Verification of an FE Model for HVB-LA-DLTL Systems  
### Engineering Background  
Taking an actual project related to the evaluation of a 1000 kV UHV substation in Central China as a background, a complete structural analysis model including HV bushings, lightning arresters, upper jumpers, down lead transmission lines and connection fittings is established. The high-voltage bushing lead structure system of the substation is composed of the upper station jumper, down lead, connecting clamp, connection fittings, high-voltage bushing terminal, high-voltage bushing, and lightning arrester. The lower ends of the high-voltage bushing and lightning arrester are connected to the transformer and the lightning arrester, respectively. Figure 1 shows a schematic diagram of the substation.  
Modern engineering already depends on numerical modeling. Among the various methods of numerical modeling that can be used in modern engineering, the most common is the FE method due to its universal nature and the relatively simple preparation of models [20]. Numerical modeling methods can directly calculate the acceleration, displacement, and stress response of a structure under continuous dynamic loading, and can also effectively simulate crack growth under dynamic loading conditions in continuous media in the field of computational fracture mechanics (CFM) [21]. In this paper, ANSYS FE software was used to establish an FE model of the high-voltage casing lead structure system. The overall size of the model is determined according to the original design drawings of a certain substation, and 1:1 scaling is conducted for solid modeling. The jumper and the down conductor in the station are 4-split conductors, and the single conductor is an expanded, heat-resistant aluminum alloy conductor of model JLHN58K1600, and linear density is 4475 kg/m\({}^{3}\). According to the principle of equivalent effect and moment of inertia, the conductor is simplified as equivalent to a round pipe section with an inner diameter of 50 mm and an outer diameter of 70 mm, as shown in Figure 2.  
The mass of the high-voltage bushing is approximately 7135 kg, the length is approximately 13.315 m, and the total weight of the arrester is approximately 9800 kg. It is divided into four sections with a length of approximately 12 m. The detailed dimensions are shown in Figure 3.  
Figure 2: Schematic diagram of the equivalent simplified cross-section of a DLTL.  
The JLHN58K-1600 expanded-diameter wire used in the high-voltage casing lead system has greater rigidity than ordinary wires. To accurately simulate the forces applied by terminals and other components in the structural system, Solid186 solid elements are used in the modeling in this paper. The transformer box is modeled with a shell unit of appropriate thickness. For complex structures such as bushings and arresters, the influence of sheds on the structure is ignored and auxiliary structures such as pressure-equalizing rings are attached as concentrated masses to the structure. The component grid and overall model are shown in Figures 4 and 5, and the material properties and element types of each component are shown in Table 1.  
Figure 3: Structural dimensions of casing and arrester.  
Figure 4: Finite element model of some components of the HV bushing lead structure system.  
Figure 5: Finite element model diagram of the structure system of the HV bushing lead.