Analytical analysis of hollow CORC cable under thermo-mechanical loads

According to engineering experience, the axial shrinkage caused by the refrigerant seriously endangers the performance of long-distance conductor on round core (CORC) cables. Since outage maintenance of hightemperature superconducting (HTS) cables is inevitable, providing appropriate compensation for cyclic temperature is one of the key technologies in the actual application of power cables. Therefore, this paper presents an analytical solution for hollow CORC cables under thermo-mechanical loads. First, regarded as an axisymmetric composite structure, the radial temperature distribution of CORC cable under Dirichlet boundary or mixed boundary conditions was calculated. Then, assuming cable ends were axially fixed, a recursive method without variables is used to evaluate its displacement, strains, and stresses. Then, an algebraic method with axial strain as a variable is developed to analyze the mechanical behavior of the CORC cable more directly. Finally, concluded from the above derivation, a matrix equation is constructed based on continuity equations and boundary conditions, which applies to isotropic and orthotropic materials with orientations. Calculation results show that the analytical solution agrees with finite element method (FEM) results. Compared to the trial results of a 360 m CORC cable, the calculation error of axial shrinkage is within 1.63 cm, and the relative error is within 6.1%. In addition, the recursive method is the fastest to calculate axial strain, while the matrix method has a significant efficiency advantage in calculating the stresses and strains of each layer.