Inferring PV Plant Reactive Power Control Mode from Ambient PMU Data

In the real-world, photovoltaic (PV) power plant controllers (PPCs) often experience internal changes (manually and/or automatically) in the form of control mode switching. Utilities or system operators are not notified when such changes occur, do not have remote access to the PPCs and may not even have knowledge of the different control modes under which a specific PPC may operate in. Since this information is not available, it is difficult to identify the critical operating mode that causes stability problems when conducting data-driven investigations. This paper proposes an approach to deduce the reactive power control mode of solar PV plants from ambient synchrophasor data by exploiting system identification techniques and statistical tests. The problem is posed as a test for conditional independence between multiple time series at the point of interconnection (POI). The effectiveness of this approach is demonstrated on synthetic as well as real world synchrophasor data from Dominion Energy’s power system.