Correction Method for Deviations in Phase Angle for PMUs at Both Ends of a Transmission Line With Unknown Parameters

The phasor measurement units (PMUs) are the eyes for the dynamic of the power system. However, the measured phase angle data from PMUs for a transmission line (TL) may coexist with different deviations, i.e., the deviations in voltage/current phase angle difference (DVPAD/DCPAD) between different ends of the TL, and the deviations in power factor angle (DPFA, i.e., the deviations in phase angle difference between voltage and current at the same end), which threaten the advanced application with PMUs. This article proposes a correction method for the phase angle data when the DVPAD/DCPAD and DPFA coexist for the TL with unknown line parameters. Specifically, first, the abnormal voltage phase angle differences and power factor angle anomalies are discussed, and the corresponding illustrative examples are presented. Second, the mathematical model for estimating phase angle deviations in a general case is presented. Third, a "two-step" method to correct the phase angle data of PMU for the TLs with unknown parameters is proposed, in which the DVPAD/DCPAD between two ends is estimated in advance, and then, the DPFA is estimated. Finally, simulation and examples with field data verify the feasibility and engineering applicability of the proposed method.