Research On Parameter Identification And Voltage Stability Index Of Long Transmission Line Based On Wide Area Measurement System

The wide-area measurement system(WAMS)has basically been installed in China’s power grid,this system can collect real-time data at each site of the entire power grid.The collected data includes amplitude,phase angle,time scale,etc,these data(WAMS data)has the characteristics of time synchronization and high accuracy.Research on parameter identification and voltage stability index of long transmission lines based on wide-area measurement systems can provide safe operation information for long transmission lines,at the same time have important significance for the safe operation of the power grid and the auxiliary decision-making for the dispatch operation of the power grid.Based on these,the main research contents of this article are as follows:Firstly,the problem of parameter identification for long transmission lines is studied.Considering the distributed parameter characteristics of long transmission lines,the total impedance and admittance of long transmission lines are multiplied by the corresponding correction coefficients to obtain corresponding accurate parameters.A parameter identification model for long transmission lines is established,the solution is solved by using Least squares.The model and algorithm simulation tests were carried out using WAMS measured data on a 220KV long transmission line in a province.The results show that the parameter identification model considering the distribution parameter characteristics of long transmission lines is more in line with the actual situation of long transmission lines.The proposed method can effectively identify long transmission line parameters and corresponding correction coefficients.Then,based on the identification of the long transmission line parameters and corresponding correction coefficients,the voltage stability index of long transmission line is studied.Based on the traditional branch model of the power system,a new distribution model of long transmission lines is established with considering the distribution parameters of long transmssion lines and adding corresponding correction coefficients.The voltage equation and the power flow equation of the branch are used to obtain the voltage stability index of the long transmission line.An example analysis is performed based on the WAMS measured data and the identified long transmission line parameters and corresponding correction coefficients.The results show that the model,algorithm,and defined index of long transmission line voltage stability are correct and effective,the obtained results can judge the voltage stability of long transmission lines.Aiming at the problem of parameter identification and voltage stability index of transmission lines,this paper studies long transmission lines that need to consider the characteristics of distributed parameters.It is provided the theoretical and methodological reference for the safe and stable operation of long transmission lines and the power grids with long transmission lines.