Research On The Thermal-induced Flexible Property And Mechanical Vibration Characteristics Of Gas-Insulated Transmission Lines

The studies on the thermal-induced flexible property and mechanical vibration characteristics of GEL have an important influence on its safe operation. The analysis that consideres influence factors such as operating environment and laying methods is missing. It is unable to understand the thermal-induced flexible property and mechanical vibration characteristics of GIL and its law clearly. GIL manufacturers are lack of theoretical basis and technical support for thermal compensation and seismic design, so the GEL transmission pipeline has a potential safety hazard, which restricts the development of GIL transmission line.In this paper, we focus on the simulation and experimental study of the thermal-induced flexible property of GEL. Firstly GIL pipeline engineering practice as the prototype, the finite-element model coupling fluid field, thermal field and force field is established, which is used to carry out the numerical analysis of the thermal expansion in GIL. At the same time,using the thermal strain testing experimental platform consisted of 126kV GEL, high-current generator, demodulator strain and strain sensors, experimental studies are conducted. Through the comparison of simulation data and experimental results, the thermal-induced flexible property of GIL is studied. The results of the research show that the thermal-induced flexible property of GEL has a positive correlation relationship with the perating current or pipeline pressure, and has a positive proportional relationship with the the ambient temperature. At the same time, the relative thermal displacement between the shell and conductor can be compensated by the reasonable configuration of the sliding pillar and the sliding support, which can improve the economic and rational of GIL thermal compensation scheme.On the other hand for the mechanical vibration characteristics of GEL, according to the national seismic code and using the finite element analysis method, the mechanical vibration characteristics of GIL are obtained by the modal analysis and response spectrum analysis. The results of the research show that earthquake response spectrumst also affects the seismic response of GIL. In order to improve the seismic capability of the GIL, the direction of GEL installation is not consistent with the direction of seismic wave propagation. At the same time, the insulators and conductors are the weak parts of the seismic response within the GIL structure, so proper selection of the mechanical parameters of insulators and conductors can significantly improve the seismic capability of the GIL.Through the experimental and simulation studies of the thermal-induced flexible property and mechanical vibration characteristics of GIL, the relevant conclusions and laws are obtained, which provide technical support and theoretical guidance for the optimal design of GIL, and lay a good foundation for the further research.