Research on Dynamic Assessment for Conductor Sag of Overhead Transmission Lines under Extreme Operating Conditions

The sag of overhead transmission lines are crucial indicators for the safe operation of the lines. In China, the maximum allowable temperature for long-term operation of conductors differs from the temperature used for sag calculation during tower installation. Under extreme operating conditions, the issues of sag distance in heavily loaded lines cannot be ignored. Therefore, this paper proposes a method for dynamically assessing the sag of overhead transmission lines under extreme operating conditions. The proposed method is validated using overload experimental data from a real 35kV overhead line in a certain region. The validation results indicate that the error between the calculated sag and the measured sag is less than 6%, basically meeting engineering requirements. Finally, based on the model proposed in this paper, a method for sag over-limit warning of overhead transmission lines under extreme operating conditions is proposed.