Stress&Strength Verification and Clamps Cracking Failures Analysis of Outdoor Ultra-high Voltage GIL Pipeline Shell Structures

Focusing on the clamps cracking failures of the first outdoor 1100 kV Ultra-high voltage Gas Insulated metal enclosed transmission Line (UHV GIL) in China, the stress&strength characteristics of the GIL pipeline shell structures and the clamp cracking failure mechanisms are analyzed. Firstly, the span combination arrangement schemes of the GIL pipeline’s fixed/sliding supports and different expansion joints are verified, according to the GIL flexibility design criteria; Then, a finite element analysis model of the continuous ultra-high voltage GIL pipeline shell structure is established based on the bending-torsion beam type elements, and the stress&strength characteristics of the ultra-high voltage GIL pipeline shell structure under different working conditions are numerically analyzed and evaluated; Finally, an refined finite element model of the ultra-high voltage GIL pipeline shell structure is established based on the shell elements with the consideration of the friction effect between the GIL pipeline shell structures and the support interfaces, and the stress&strength characteristics of the clamps under limited displacements and jamming conditions are analyzed. Correspondingly, the clamp failure mechanisms in the outdoor ultra-high voltage GIL pipeline shell structure are explained, and the relevant optimization design suggestions are given.