Synchrophasor Phase Angle Data Unwrapping Using an Unscented Kalman Filter

The wrapping operation causes discontinuities in phase angle measurements from synchrophasor devices. While various unwrapping algorithms traditionally used for synchrophasor data have proven effective under typical operating conditions, they are likely to fail when faced with atypical data because of equipment malfunctions. For example, the underestimation of the phase angle jump when the data originates from a device with an internal clock or other timing mechanism can introduce this kind of error. This letter proposes using an unscented Kalman filter (UKF) for unwrapping one dimensional synchrophasor data. This technique is especially suitable for analyzing low-quality data. The effectiveness of this method is demonstrated on real phase angle measurements from devices with documented timing issues in the Dominion Energy power system.