Rapid calculation model for transient temperature rise of complex direct buried cable cores

Abstract

Actual direct buried cable is a complex model that contains backfill sand and external soil. To improve dynamic load level and utilization of buried power cables, it is crucial to quickly calculate power cable core temperature under sudden changes in load. The complex buried cable structure is decomposed into three parts so as to improve the accuracy of calculation. These three parts are the cable body, the backfill sand and the external soil, which temporary temperature rise can be solved by respect transient thermal circuit models separately and then add them up to obtain the cable core temperature. In actual project, the values of the transient thermal circuit model elements can be solved in advance and made into a table, and the relevant parameters can be obtained by checking the table in use. The backfill sand is only related to its heat conductivity, the external soil is related to its heat conductivity and burial depth. There transient thermal circuit model elements values can be fitted by an expression with the environment parameters, which can improve application scope of the transient thermal circuit model. The experimental results of the simulation show that, after knowing cable type and environment parameters, the transient thermal circuit model elements can be obtained by looking up the table and calculating by expressions, thus enabling fast calculation of the value for the cable core temperature variation while ensuring the accuracy of the results, and can meet the requirements in engineering.