Research on thermomechanical effects and influencing factors in high voltage cable under multiphysics field coupling

The interior of a high-voltage cable causes a state of extrusion due to thermomechanical effects; the resulting stress and deformation can easily lead to the destruction of the cable structure. Aiming at the problem, we establish an electromagnetic–thermal–force field model of a high voltage cable. By considering the influence of temperature on the material properties, a bidirectional couple simulation of electromagnetic and thermal fields is established. The thermal load excitation is introduced into the structural field, and the simulation calculation of thermal strain and thermal stress of the axial and radial layers is realized. The influence of ambient temperature, load current, and circulating current defect factors on the thermal–force characteristics of each layer of the cable is studied. The results show that the response of the insulating layer to the thermomechanical effect is the most significant, and its characteristic change law shows the nonlinear trend. In addition, the thermal strain of the cable has an approximate axial symmetry; the axial thermomechanical effect is significantly higher than the radial direction. The maximum axial and radial deformations of the cable when running at full load are 1.21 and 0.16 mm respectively. Among the three influencing factors, the impact of circulating current defects on the thermomechanical effect of cables is the most obvious. The thermomechanical effect of the cable approximately is positively related to the square of the circulating current defect factors, the load current, and the ambient temperature.