Analysis of transient temperature rise in tunnel cables is a critical factor in determining the safe and stable operation of tunnel cable systems. The Laurent series expansion is introduced to simplify the process of solving the node admittance matrix

so as to obtain the distribution of metal sheath circulation along the entire tunnel cable. Considering the asymmetrical laying method of tunnel cables and the impact of varying temperatures on conductor resistance

in conjunction with the IEC-60853 standard

calculation method is derived for the transient temperature rise in the tunnel cable system that takes the influence of metal sheath circulation and time-varying conductor resistance into account. Based on the corrected analytical model and numerical simulation method

the study on the transient temperature rise is conducted focusing on the 220 kV high-voltage tunnel cable project. The results indicates that the transient temperature rise in the cable system is influenced by multiple factors such as the laying method

laying spacing

ambient temperature

and operating load. Under daily cycle load current

with tunnel cables laid in horizontal and trefoil methods

the average relative errors between the transient temperature rises of the cable core obtained by the numerical simulation method and corrected analytical model are 3.616% and 4.515%

respectively

both within the acceptable range (less than 5%). The transient temperature rises of the outer sheath calculated by both methods are essentially consistent

with maximum temperature rise differences of 1.214 and 1.248 ℃

respectively. The work provides a new calculation method and a reference for engineering applications in analyzing the transient temperature rise of tunnel cable systems.