Temperature and Electric Field Distribution Characteristics of a DC-GIL Basin-Type Spacer with 3D Modelling and Simulation

Abstract

The temperature properties of real-type direct-current gas-insulated transmission lines (DC-GIL) with a basin-type spacer were investigated by the finite element method in this paper. A horizontally installed model was established and the temperature distribution was obtained with a 3D model. The specific heat capacity and thermal conductivity of the spacer were measured and applied in the simulation. The results show that the temperature of the convex surface was slightly higher than that of the concave surface. With an increase in the SF6 pressure, the temperature of the spacer decreased, which can be attributed to the improvement of convection due to increases in the heat capacity per unit volume. With an increase in the ambient temperature, the temperature of the spacer increased linearly. The temperature difference between the inner and outer parts of the spacer increased with increases in the load current. Besides, an obvious increase in the surface electric field strength appeared under the influence of the thermal gradient compared to the results without the thermal gradient. Thus, special attention should be paid to the insulation properties of the spacer considering the influence of temperature distribution. This study evaluates both the thermal and insulation characteristics of the GIL along with the spacer under various conditions.

Transient surface charge of SF 6 ‐filled direct current gas‐insulated transmission lines insulator under thermal‐electric coupled fields: effects of ambient temperature, load current and gas pressure

“…According to the simulation [19] and measurement [30] results of temperature rise, the steady thermal gradient of the GIL and insulator will be achieved in few hours. While the accumulation of surface charge will last for thousands of hours [14,15,17], and slight charge can be obtained at the first couple of hours.…”

“…Since horizontally installed GILs are more widely employed in the system compared with the vertically installed sections, the surface charge distribution of horizontally installed DC-GIL insulators under coupled fields should be revealed. A 3D model is necessary in the simulation of surface charge under coupled fields, as the thermal gradient in the GIL and the insulator does not follow the 2D axisymmetric pattern [19,20].…”

Improved method in calculating the surface charge distribution of DC‐GIL insulators with 3D geometry models

“…The conduction, convection, and radiation were considered in the heat transfer inside the GIL, and the shear stress transport turbulent flow model was selected to deal with the convection in the SF 6 gas. The detailed mechanism of the heat generation and conduction has been reported in our published work [27]; thus it is not discussed in this section. the simulation of a thermal gradient, the current was 3150 A, the SF 6 pressure was 0.5 MPa and the ambient temperature was 20 • C. The temperature distribution of the insulator surface is shown in Figure 10.…”

Influence of volume and surface conductivity on the transient surface charge characteristics of DC‐GIL insulator under thermal–electric coupled fields

“…The Joule heat from the insulator and SF 6 gas due to leak current is extremely low compared with the heat from the conductor due to load current. Second, it takes about 5–10 h for the thermal gradient to reach stationary state according to previous researches [26–28]. While it takes about hundreds to thousands of hours for the charge to reach saturate/stationary state [14, 29].…”

“…Two circulations flow in different directions in the pipe [27]: The gas heated by the conductor is lifted up from the conductor, and goes along the symmetry plane to the top of the enclosure. Then, the gas goes down along the inner surface of the enclosure to the bottom.…”