Identification of Transmission Line Parameters Using Noisy PMU Measurements

Information about power line parameters in a power system is important for many reasons. Remote relays use line impedance information for proper tuning. Power flow algorithms also use line parameters to evaluate system status. Line parameters are used to localize faults in the power line. Therefore, the algorithm for estimating the line parameters must be accurate. The work aims to develop a method of noise-free identification of parameters of power lines based on ABCD parameters. To date, synchrophasor measurements are widely used to evaluate parameters. In practice, synchrophasor measurements of currents and voltages are measured with interference. Estimates of the line parameters are very sensitive to the presence of noise in synchrophasor measurements. The presence of interference in both the input and output signals does not allow us to obtain high-precision estimates of the parameters by the least squares method. Using the symmetry property of a four-terminal network (A = D) makes it possible to increase the accuracy of the estimated parameters by solving an overdetermined system of linear equations with complex coefficients. To evaluate the ABCD parameters of a four-terminal network using synchrophasor measurements, the work uses the weighted total least-squares method, which allows one to obtain high-precision parameter estimates. The solution to the problem of total least squares is carried out based on representing the displaced normal system of equations in the form of an augmented system of linear algebraic equations. A computational experiment showed high accuracy of the proposed identification algorithm in comparison with known methods based on the least squares method.