Synchronized phasor based on-line parameter identification of overhead transmission line

Overhead transmission line is one of the basic elements of power systems, whose parameters are of great importance to the normal operation of the power system. Thereby how to acquire the accurate parameters of overhead transmission lines is crucial. In this paper a novel method to identify the transmission lines' parameters on-line is deduced, where the data from PMU/WAMS (phasor measurement unit/wide area measurement system) is used. Furthermore, the impact of conductor sag on the line parameters is analyzed. According to the parameter variation, abnormal conductor sag can be identified and then the early warning message can be sent out for overload and other abnormal condition causing the sag. Besides, the proposed algorithm with different data windows is implemented and the corresponding precision is analyzed. The simulation results show that the proposed method can obtain precise overhead transmission line parameters on-line and identify abnormal conductor sag effectively.