Online measurement of T-connection transmission line parameters based on multi-interval synchronized measurement information

Accurate transmission parameters are very important for state estimation, power flow computation and network losses analysis. The research work around online measurement of T-connection transmission line parameters was launched. An online measurement algorithm of transmission line was proposed. The equations were listed by analyzing the equivalent circuit of T-connection transmission line and using multi-interval synchronized Information of the T-connection transmission line. Then, by solving the equations iteratively, the parameters of the transmission line can be calculated. In order to reduce the measurement error due to the waving of electric network frequency, a windowed interpolation FFT algorithm was proposed to analysis the synchronized sampling data. In this paper, the simulation results of the proposed method are given. Finally, the online measurement process of one 110 kV transmission line containing T-connection lines by the proposed method are described, the online measurement results are given and compared with the design values. Results from both simulation and online measurement show that the proposed online measurement method is feasible and its requirements of engineering measurement.