44 / 2024-03-29 18:33:19

Simulation and Analysis of Internal Arc Plasma Motion in GIL based on Magnetohydrodynamics model

internal arc plasma motion,GIL,magnetohydrodynamics,simulation

Gas insulated transmission lines (GIL) is a kind of high voltage and high current power transmission equipment with SF₆ gas insulation and coaxial arrangement of conductor and enclosure. However, GIL lacks effective monitoring methods for internal fault arcs differenced from GIS equipment with arc sensors arranged. The internal fault arc between inner conductor and outer enclosure is usually caused by metal particles in GIL, which induce the field strength distortion, and damage the conductor and enclosure. After the internal arc breakdown, it will move along the axial direction of inner conductor under the action of Lorentz force and when the hot arc plasma meets the basin insulator, surface discharge of insulator tends to happen. This paper focuses on establishing a dynamic model of internal arc plasma based on magnetohydrodynamics (MHD) simulation to reveal the arc motion characteristics in GIL. Firstly, the cross section of GIL geometric structure is selected as the observation domain to model fault arc plasma motion, as shown in Fig. 1. Then, a MHD model of arc plasma coupled with multi-physical field is established, as shown in Fig. 2, which is combined with the control equations of electromagnetic and gas flow field. The electric field boundary condition of arc plasma region is set as different alternative currents of power frequency. In the remaining area, outside of arc plasma region, it is filled with SF₆ and the pressure of gas is assigned as 0.45 MPa. Secondly, the arc motion process can be visually studied and analyzed by the computing the distribution of temperature field of arc plasma, as shown in Fig. 3. The positions of maximum temperature around the junctions of the arc plasma with the inner conductor and outer enclosure are regarded as the arc root positions. The speeds of arc roots are obtained by conducting the relationship between the arc root position and time, as shown in Fig. 4. Finally, the simulation speed of arc root is compared with the experimental data under the same condition and the model have been effectively verified. This paper provides a reference for the internal arc fault analysis of GIL.