RT-HIL Implementation of Synchrophasor Phase Angle Unwrapping using ROC Method

With the growth in the transmission and distribution infrastructure, there has been a rising need for monitoring various parameters of the system in real-time. Phasor measurement units (PMUs) are capable of providing time-synchronized values of bus voltages and currents, which can further be utilized for visualization purposes. The phase angles computed by PMUs are wrapped around +/− 180 degrees, and proper unwrapping techniques must be incorporated in the phasor data concentrators (PDCs) to obtain accurate values of angle differences of two PMUs which are located at different locations. This paper focuses on the unwrapping of phase angles that are obtained from PMUs placed in a real-time hardware in the loop (RT-HIL) environment, by using the rollover counter (ROC) method. The OSIsoft PI system is used as a PDC for collecting the synchrophasor data and performing the various calculations on the phase angles obtained from the PMUs. The PI system does not have any unwrapping techniques and hence the ROC method was incorporated in this paper to successfully unwrap the phase angles.