Steady-state PMU data selection for parameter identification of transmission line considering the influence of measurement error

Phasor measurement units (PMUs) are important data source for parameter identification of the transmission line (TL). However, the "seesaw" phenomenon exists in the identified susceptance and reactance (B&X) based on real-world PMU data, that is, the accuracy of X increases with the increase of the active power transmitted in the TL (APT), while the accuracy of B decreases. Recognizing the above, with the approximations of the opposite influence characteristics of relative errors of the identified B&X with respect to the APT, this paper proposes a method of selecting the steady-state PMU data to improve the accuracy of the identified B&X. In detail, firstly, the "seesaw" phenomenon of the identified B&X is demonstrated based on the real-world and the simulated PMU data. Secondly, the approximate relationship between the relative errors of B&X and the APT is derived and summarized, which can explain the "seesaw" phenomenon theoretically. Thirdly, combining the above relationships and the principle that B/X identified with the low/high APT respectively, the practical thresholds of APT for B&X identification are determined, and then, the method for selecting the steady-state PMU data is proposed. Finally, results using both the simulated and the real-world data demonstrate the effectiveness and practicality of the proposed method.