Calculation Method of Conductor Sag Based on Radial Temperature and Creep

The sag of the transmission line is an important index for its safe operation. Focusing on the calculation deviation of conductor sag caused by the non-uniform temperature distribution of transmission lines and the creep, the influence degree of the radial temperature and the creep on the sag calculation model was studied in this paper. Firstly, the finite element model of the conductor was established based on its physical composition and structural characteristics. Considering different operating conditions of the transmission line, the radial temperature was analyzed through the finite element simulation. Secondly, considering the radial temperature difference of stress, the radial thermal expansion and the creep, the sag calculation model was built. Based on the force balance principle, the relationship among the radial thermal expansion considering the radial temperature difference, the stress and the strain of the conductor was studied and the relationship between creep and strain was analyzed. Then the conductor sag was calculated through the function of the strain and the sag. Finally, in order to verify the accuracy and practicability of the sag calculation model, the model was verified by a 110 kV transmission line in Shaanxi Province. The results show that the influence on the accuracy of the sag calculation from largest to smallest are the creep, the radial temperature difference and the radial thermal expansion based on the 110 kV transmission line in Shaanxi Province. Without taking into account the radial temperature difference, the radial thermal expansion and creep, the error of sag was in the range from –45.2% to –30.0%. And the maximum error was 45.2%. The error range under the optimization model of sag in this paper was less than 1.1%. When the influence of the radial temperature difference and the radial thermal expansion on the sag is ignored, the error of sag is existed and the error becomes greater with the increase of the radial temperature difference. © 2023 Editorial Department of Journal of Sichuan University. All rights reserved.