Research on the Thermal Expansion and Contraction Characteristics of UHV AC GIL Expansion Joint

As an integral part of the GIL system, GIL expansion joints are closely related to the safe and reliable operation of GIL equipment. The current density and electromagnetic loss distribution of GIL expansion joints under rated operating conditions are calculated, and the eddy current field-temperature field-force field multi-physical field coupling model is used as an excitation to analyze the temperature rise and thermotropic expansion of expansion joints under environmental conditions. The results show that the temperature distribution and axial expansion of the expansion joint under rated conditions are axisymmetric, with a maximum temperature rise of 35.6 °C and a maximum axial expansion of 0.078 mm. conductor heating and solar radiation are the main causes of the expansion joint temperature rise, and the axial thermal strain of the expansion joint is approximately linearly related to the load current and ambient temperature. Increased solar radiation will lead to an increase in temperature difference between the top and bottom of the corrugated tubes and an increase in thermal expansion.