Thermal Circuit Model for Transient Temperature Rise Calculation of Trench Cable Based on the Thermal Coupling Coefficient Method

The accurate calculation of the transient temperature rise during cable operation is of key importance for the dynamic capacity enlargement system, and it’s a challenge to calculate the impact of thermal coupling effects between cables when solving the transient temperature rise for the multi-circuit cable. In this paper, a decoupling method is applied and a transient thermal circuit model based on thermal coupling coefficient method (TCCM) is proposed to quickly calculate the transient temperature rise of a double-circuit trench cable. The transient thermal circuit model of a double-circuit trench cable is established, and the parameter values of heat source, thermal resistance and heat capacity of the thermal circuit model are determined by IEC standard and finite element method (FEM). For the double-circuit trench cable, a heat source is introduced to consider the thermal coupling effects from the adjacent circuit, and TCCM is used to determine the value of the added heat source. The results show that the transient circuit model of double-circuit trench cable based on TCCM can accurately calculate the transient temperature rise of the cable under eight different step loads, and the maximum deviation between the results of TCCM and FEM is within 1 K.