Refinement of Transmission Line Equivalent Circuit Parameters at Power System State Estimation by PMU Data

The significance of the electric power system state estimation is getting increasingly relevant for control of the power industry facilities. The quality of state estimation results depends on the quality of input data, i.e. SCADA and PMU measurements, a properly constructed equivalent circuit based on the signals about position of switching equipment, and accuracy of equivalent circuit parameters (resistance, reactance, conductance, and susceptance of transmission lines). The evolution of WAMS alters the understanding of characteristics of the measurements involved in the state estimation procedure and the properties of the procedure itself. Therefore, special attention is paid to the improvement in quality and increase in accuracy in all stages of the measurement cycle, the requirements of failure-free synchronization of phasor measurements, and development of algorithms for SPM validation. The paper is concerned with the refinement of the equivalent circuit parameters, by using PMU measurements, and the influence of such refinement on the power system state estimation results. The validity of PMU measurements is preliminarily checked by the method of test equations and wavelet analysis. Results of calculations for two 750 kV transmission lines based on 10-min archives of PMU measurements prove the suggested approaches are practical and efficient.